MLZ User Meeting 2023

4 Dec 2023, 12:00 → 5 Dec 2023, 17:00 Europe/Berlin

Munich Marriott Hotel

Thank you very much! 

 

You can download the collage in high resolution below! 

 

The MLZ User Meeting took place at the Munich Marriott Hotel on Dec. 04^th and 05^th, 2023 - despite snow and ice! 

208 of 250 registered participants made it, gave and listened to 63 talks (some remote on short notice), and discussed 116 posters. 

The first day was dedicated to specialized workshops organized by our Science Groups, as always. And in the evening, we had an excellent conference dinner at a typical Bavarian restaurant - just before the ice rain started...

On the second day, the MLZ Directorate updated on the current situation at the MLZ. Furthermore, scientific plenary talks by Piero Baglioni (Uni Florence) and Michael Gradzielski (TU Berlin) and the poster session made this day! 

Our Data Evaluation Group (DEVA) also offered two full-day workshops on Rietveld and SteCa as a satellite. 

We enjoyed exciting talks, well-designed posters, and delightful discussions!

 

 

MLZUsers2024_Collage.jpg

Monday, 4 December

12:00 Lunch

Material Science: MS I

1 Welcome be Science Group

2 Stabilizing the Li/Li1.3Al0.3Ti1.7(PO4)3 interface by introducing an ultrathin single-ion conducting interlayer

Lithium metal is considered as one of the most promising anode candidates for high-energy batteries [1]. However, safety concerns induced by the formation of Li dendrites and the high reactivity at the electrode/electrolyte, resulting in a continuous electrolyte decomposition hinder the practical application [2]. It is anticipated that the use of non-flammable inorganic solid-state electrolytes can resolve these safety issues, but solid ceramic electrolytes generally suffer from poor physical contact with the electrode and poor electro-/chemical stability.
Herein, we report on a thin and flexible hybrid electrolyte composed of NASICON-type Li1.3Al0.3Ti1.7(PO4)3 (LATP), a polymer binder, and a small amount of an ionic liquid. To reinforce the interfacial stability between LATP and Li, we coat an ultrathin single-ion conducting polymer on the Li metal surface. The implementation of this interlayer enables a substantial extension of the cycle life of symmetric Li//Li cells and Li//NCM88 full-cells as the positive electrode active material. The superior performance achieved herein is mainly attributed to: (1) the prevented direct contact between LATP and Li; (2) the regulated Li+ flux at the electrode/electrolyte interface; and (3) the promoted intimate contact between PSiO and Li via the formation of Si−O−Li bonds.

References
[1] B. Horstmann et al., Energy Environ. Sci., 14 (2021) 5289-5314.
[3] X. He et al., Nat. Rev. Mater. 6 (2021) 1036–1052.

Speaker: Dominic Bresser (Karlsruhe Institute of Technology (KIT))

3 Charge Relaxation within Silicon/Graphite Anodes – A Multi-Method Study

As silicon/graphite (SiG) composites are more commonly used as the anode active material in commercial Li-ion batteries,1 the importance of investigations of the (de-)lithiation behavior of the blended anodes grows. In this study, the charge redistribution between graphite and silicon was investigated in graphite-NMC 622 and SiG (~20 wt.-% Si) – NMC 622 bilayer pouch cells using in situ and operando X-ray diffraction (XRD). In addition, ex situ and in situ optical microscopy (IOM), as well as 3D microstructural resolved simulations employing digital twins of the cells, were carried out. Different SOC values (0%, 25%, 50%, 75%, and 100%) and two different C-rates (0.1C and 0.5C) were compared in cells during operation and in the relaxed state. Insights into the relaxation process at 75% SOC were gained by tracking of the charge redistribution in IOM cells. Ex situ optical microscopy measurements reinforced the findings of the IOM measurements. Both XRD and optical microscopy showed the disappearance of Li in the graphite component of the SiG anode during the relaxation period (≥24h) at SOC ≤75%, indicating a redistribution of Li from graphite into Si in the anode. The simulations allowed a detailed analysis of the Li concentration in both active material components during charge and relaxation, verifying the observations from the XRD and microscopy experiments. The gained insights can support a better understanding of aging of blended SiG anodes during operation.

Speaker: Christin Hogrefe (Zentrum für Sonnenenergie- und Wasserstoff-Forschung Baden-Württemberg Ulm)

4 Neutron depth profiling and GD-OES as tools for characterization of Li plating in Si/graphite anodes from Li-ion battery cells

The loss of Li inventory is a common aging mechanism in Li-ion batteries. To better understand these underlying reversible and irreversible degradation processes in Si/graphite electrodes, depth-resolved methods need to be used to obtain information on the decomposition products of the lithium-containing electrolyte across the electrode thickness. In this work we present two Post-Mortem analytical methods, which can be used to obtain quantified Li depth profiles to depths bigger than 10 µm from the electrode surface, the neutron depth profiling (NDP) and glow discharge optical emission spectroscopy (GD-OES). The validation of GD-OES using NDP by examining the Si/graphite anodes from cylindrical 21700 cells is presented. These two methods are complementary to each other since they are based on different measurement principles and an improvement for the GD-OES calculations of depth profiles of Li in electrodes has been established. It has been demonstrated that the preferential sputtering can occur on the anode surface during the GD-OES measurements. This phenomenon is caused by the higher sputter rate of Li, as it is mainly present in the Li plated layer or in the solid electrolyte interface (SEI).

Speaker: Ivana Pivarníková

Neutron Methods: NM I

5 Welcome by Science Group

6 Imaging the Magnetization Process in Silicon Steel using Polarized Neutrons

Ferromagnetic metals are commonly used as high performance magnetic core materials. Especially for application in transformers, grain oriented (GO) silicon steels stand out due to their uniaxial magnetic properties, which are founded in their strongly textured crystal structure. Since most techniques for investigating magnetic properties integrate over large sample volumes (magnetization and magnetic susceptibility) or are restricted to the sample surface (Kerr-effect microscopy), it is challenging to obtain information on the local bulk properties. In this regard, polarized neutron imaging (PNI) is a perfectly suited method. It combines the spatial resolution of imaging with the magnetic interaction of the neutron spin. By evaluating changes in the spin-polarization, effects of magnetic order and disorder can be analysed. The technique has seen substantial developed in recent years, with applications such as visualizing large magnetic domains or magnetic vector-fields. Here, we present a study of the magnetization process of a GO silicon steel sheet, while also focusing on the experimental setup, since PNI has high demands towards the magnetic field setup. We have combined finite element and ray tracing simulations to model the magnetic environment as well as its impact on the neutron polarization. Our results show how PNI can be used to understand the magnetization process in a ferromagnetic material with a focus on the impact of macroscopic inhomogeneity.

Speaker: Dr Alex Backs (Lund University)

7 Event Mode Neutron Detection for High Spatial and Temporal Resolution Imaging

Recent developments in event driven camera systems allow the construction of a new type of scintillator-based event mode imaging devices. This type of detector records data for individual neutron interactions in a scintillator screen. By analyzing each event individually, improvements in temporal and spatial resolution as well as noise supression are possible. At the same time, it has the same fexibility in terms of field of view and scintillator material as well as the continous readout capability as raditional scintillator based neutron cameras.

The preseation contains a detailed explanaion of the principles of event mode neutron imaging. Afterwards, the results from several measurements are shown to illustrate its capabilities. The main focus of the talk is on the combination hof high temporal and spatial resolution for applications such as time of flight (ToF) imaging and modulation of intensity with zero effort (MIEZE).

Speaker: Alexander Wolfertz (TUM FRM2)

8 High-Precision Visual Servoing for the Neutron Diffractometer STRESS-SPEC at FRM II

The Heinz Maier-Leibnitz Zentrum (MLZ) operates at Germany’s sole neutron source FRM II the diffractometer STRESS-SPEC optimised for fast strain mapping and texture analyses. The STRESS-SPEC group was the first to pioneer sample handling and positioning via industrial robots at neutron diffractometers [1, 2]. However, the current robot is limited in its use due to insufficient absolute positioning accuracy of up to ± 0.5 mm in some cases. Usually, an absolute positioning accuracy of 10% of the smallest gauge volume size – which in case of modern neutron diffractometers is in the order of 1×1×1 mm3 – is necessary to allow accurate strain tensor determination and correct centering of local texture measurements. The original robot setup at the neutron diffractometer STRESS-SPEC has therefore been upgraded to a high accuracy positioning/metrology system. We will give a short introduction on the complete measurement process chain for the new robot environment. To achieve a spatial accuracy of 50 µm or better during measurement of the full strain tensor, the sample position is tracked by an optical metrology system and actively corrected, which we will show in detail.

[1] H.-G. Brokmeier et al., Mater. Sci. For. 652 (2010) pp. 197–201.
[2] C. Randau et al., Nucl. Instr. Meth. A: 794 (2015) pp. 67–75.

Speaker: Michael Hofmann

Nuclear, Particle, and Astrophysics: NPA I

9 Welcome by Science Group

10 Free neutron beta-decay experiment PERC

High-precision measurements of angular correlations in free neutron beta-decay address a number of questions which are at the forefront of particle physics. PERC (Proton Electron Radiation Channel) is the new generation beta-decay experiment. Its aim is to measure correlation coefficients with high accuracy (10-4) and the experiment is currently under construction at the TUM FRM II/MLZ.

In this talk some results of the PERC's predecessor, namely PERKEO-III, and the status update for PERC will be presented. Design study of the CREScent experiment, a proof-of principle experiment aiming to combine the CRES (Cyclotron Radiation Emission Spectroscopy) technique with the signal amplification qualities of an RF cavity, will be introduced.

Speaker: Irina Pradler (ATI - TU Wien)

11 Improvement of the analytical workflow for prompt-gamma activation analysis

The analysis workflow of Prompt gamma activation analysis at the BNC’s PGAA and NIPS-NORMA facilities, at the MLZ FRM II PGAA station, and many other centers worldwide relied on the use of the Hypermet-PC gamma spectrometry software and the ProSpeRo concentration calculation Excel macro. This evaluation procedure was established in the late nineties and was compatible with the computing environment and data acquisition hardware of that era. The procedure has been validated for several matrices and provided excellent results, as well as uncertainty budgets for about 25 000 PGAA spectra over the years.

However, that peak fitting procedure required up to an hour of an experienced analyst, and the count rate of the detector had to be limited to avoid the distortion of the peak shapes. To overcome this limitation, and establish a common basis for the analytical practice, a Budapest-Garching collaboration was formed.

At BNC, computer-controlled sample changers and neutron collimators were installed, and new, state-of-the-art ORTEC DSPEC 502A gamma spectrometers were put in place.

The much-improved data acquisition had to be matched with a capable and more automated evaluation procedure. The 2022.2 version of the Hyperlab software package was developed. Finally, the ProSpeRo concentration calculation utility was made compatible with Hyperlab’s efficiency and peak list format.

Speaker: Dr László Szentmiklósi (Centre for Energy Research, Hungarian Research Network)

12 Two step gamma cascade method for study of nuclear structure parameters

Investigating nuclear structure parameters is a crucial in low-energy nuclear physics. The comprehension of gamma transitions, level schemes, nuclear level density, and radiative strength functions is necessary for both fundamental and applied research. To this end, the two-step gamma cascades method, involving the detection of gamma coincidences subsequent to neutron capture, specifically the (n,2γ) reaction, has emerged as a robust approach for obtaining spectroscopic data and insights into level density and radiative strength functions. This method facilitates an in-depth exploration of the complex dynamics governing interactions and transitions between Fermi- and Bose-states of the nucleus, particularly in proximity to the neutron binding energy. These intranuclear processes substantially differ from their counterparts in classical and high-temperature superfluidity. These distinctions arise from the unique characteristics of the investigated nucleus, including its shape, nucleon parity, and the presence of diverse nucleon types, such as protons and neutrons. Thus, the two-step gamma cascades technique has been successfully employed in the examination of 45 nuclei within the mass range of 28<A<200. This talk will provide a concise overview of the method, supplemented by illustrative examples drawn from recent research.

Speaker: Nikola Jovancevic (University of Novi Sad)

Positrons: e+ I

13 Welcome by Science Group

14 First operation of APEX-LD, a levitated dipole trap designed for e+e- plasmas

The mission of the APEX-LD (A Positron-Electron eXperiment - Levitated Dipole) trap is to provide a compact (~10-liter) volume of closed dipole magnetic field lines, to be used for the confinement and study of low-temperature, long-lived e+e- pair plasmas. The requirements for this application posed a number of challenges for experiment design and engineering. (These included, e.g., the need to repeatedly make and break thermal contact with cryogenically cooled components in a vacuum environment; excitation of current in the superconducting "floating coil", followed by long-duration, feedback-stabilized levitation; and a demand for robustness to repeated quenches and possible mechanical shocks). A comparable number of experiment design and engineering solutions have been found and implemented, and APEX-LD has successfully started operation, enabling the first electron experiments to commence in August 2023. This talk will outline the design of the APEX-LD systems, then present the highlights of the experiment commissioning (e.g., efficient current induction to ~0.5 T on axis, levitation times in excess of three hours, and slow/"gentle" quenching of the non-insulated HTS [high-temperature superconducting] coil). Finally, it will describe results from first experiments (i.e., magnetic field line visualizations and e- injection) and next steps for making e- plasmas and later injecting cold, dense pulses of e+.

Speaker: Alexander Card (Max-Planck-Institut für Plasmaphysik)

15 Positron beam tomography using fast Faraday cup detectors

In the field of continuous low energy particle beams, Faraday cup detectors have been traditionally considered a way of precisely assessing the particle flux, given a few minutes of integration time and assuming no spatial resolution is required. Two years ago we presented a novel Faraday cup design, pursuing the aim is of providing fast and position-sensitive measurements. We will present now the first measurement of a positron beam using a locally-amplified Faraday cup detector and demonstrate how the position sensitivity of the detector can be leveraged to perform a full two-dimensional tomography of the beam shape.

Speaker: Francesco Guatieri (Università degli Studi di Trento)

16 Commissioning gamma detector array by imaging evolution of a pulse of >10⁴ positrons in a dipole trap: efficient injection, toroidal homogenization, and radial diffusion to the wall

We present techniques for diagnosing magnetically confined electron-positron pair plasma [1]. Direct and positronium-mediated annihilation result in overlapping volumetric γ sources, and the 2-γ emission from these volumetric sources can be tomographically reconstructed from coincident counts in multiple detectors. Transport processes result in localized annihilation where field lines intersect walls and limiters. These localized sources can be identified by the fractional γ counts on spatially distributed detectors. In order to demonstrate the effectiveness of annihilation-based techniques, we present measurements from a gamma detector array imaging injection, toroidal homogenization, and radial diffusion of a pulse of >10^4 positrons in a permanent magnetic dipole trap. An annihilation-gamma array consisting of 21 detectors placed in reentrant ports 1cm from the trap electrode wall, detects ~1000 gammas per shot. FPGA processing of the detector signals timestamps detections to 24ns accuracy and identifies ~100 coincident lines of response per shot. The efficiency of injection is characterized by the absence of a prompt annihilation signal. The toroidal homogenization of the positron pulse during the first 100μs is characterized by pile-up annihilation signals generated by dumping all remaining positrons. The radial diffusion and confinement time are characterized by counting annihilations over the confinement time. [1] von der Linden et al. (2023) J. Plasma Phys.

Speaker: Jens von der Linden

Quantum Phenomena: QP I

17 Welcome by Science Group

18 Soft Phonon Mode Triggering Fast Ag Diffusion in Superionic Argyrodite Ag$_8$GeSe$_6$

The structural coexistence of dual rigid and mobile sublattices in superionic Argyrodites yields ultralow lattice thermal conductivity along with decent electrical and ionic conductivities and therefore attracts intense interest for batteries, fuel cells, and thermoelectric applications. However, a comprehensive understanding of their underlying lattice and diffusive dynamics in terms of the interplay between phonons and mobile ions is missing. Herein, inelastic neutron scattering is employed to unravel that phonon softening on heating to $T_c\approx350\,\rm{K}$ triggers fast Ag diffusion in the canonical superionic Argyrodite Ag$_8$GeSe$_6$. Ab-initio molecular dynamics simulations reproduce the experimental neutron scattering signals and identify the partially ultrafast Ag diffusion with a large diffusion coefficient of $10^{−4}\,\rm{cm}^{−2}\rm{s}^{−1}$. The study illustrates the microscopic interconnection between soft phonons and mobile ions and provides a paradigm for an intertwined interaction of the lattice and diffusive dynamics in superionic materials.

Speaker: Frank Weber (Karlsruhe Institute of Technology)

19 Long-range order, re-entrant spin glass and spin liquid correlations in anion disordered Gd2Hf2O7

Pyrochlore antiferromagnets (AFM) Gd2T2O7 (T: tetravalent metal elements) are prototypical materials for realizing classical spin liquid states. However, all of them have been observed to show long-range magnetic order [1-3]. Previous specific heat data of Gd2Hf2O7 show a tiny sharp peak on the top of a large broad maximum indicating a long-range AFM order [4]. However, our sample does not show that sharp peak in specific heat, but the ac susceptibility evidences an ordering transition followed by a spin-glass transition. Using neutron diffraction, we found that the sample has oxygen Frankel defects and undetectable Gd/Hf anti-site defects. The polarized neutron diffuse scattering pattern shows liquid-like scattering without any magnetic Bragg peaks. The subtle long-range order and re-entrant spin glass are attributed to bond disorder due to oxygen anion disorder.

References
[1] J. S. Gardner, et al., Reviews of Modern Physics 82, 53 (2010).
[2] X. Li et al., Phys. Rev. B 94, 214429 (2016).
[3] A. M. Hallas et al., Phys. Rev. B 91, 104417 (2015).
[4] M. D. Alice et al., J. Phys: Conden Matter 20, 235208 (2008).

Speaker: Jianhui Xu (RWTH Aachen, JCNS)

20 Inverse Exchange Bias and Anomalous Magnetization Behavior in Negative Magnetization Compounds, La1-xPrxCrO3

The La1-xPrxCrO3 compounds with x = 0.8, 0.85, and 0.87 exhibit the intriguing negative magnetization (NM) state below the compensation temperature, TCOMP. While only positive magnetization is found for x = 0.9 compound below its magnetic ordering temperature. An anomalous dc magnetization behavior is observed for these compounds. A maximum dc magnetization is found for x = 0.8 compound, after that it starts to decrease, shows a minimum at x = 0.87 followed by an increase with the largest magnetization for x = 0.9 compound, thus indicating an anomalous dc magnetization behavior. Polarized neutron depolarization (Pf) is found to follow the following order: P_f^(0.9 ) 〖>P〗_f^0.8 〖>P〗_f^0.85>P_f^0.87 and thus has provided the magnetic domain-level understanding of observed anomalous dc magnetization behavior. More interestingly, inverse/positive exchange-bias (EB) is observed for the NM compounds in the negative magnetization state (T< TCOMP). The Rietveld refinement of the neutron diffraction data reveals that Cr moments in all compounds orders in Gy type antiferromagnetic fashion. We have fitted the dc magnetization data using Cooke’s model, and the internal magnetic field/polarized Pr moment (MPr) and MCr are estimated. The internal field acting on the Pr3+ sublattice by the ordered Cr3+ moment is found to be negative for x = 0.8, 0.85, and 0.87 compounds and positive for x = 0.9 compound, and thus explains the presence and absence of NM in the compounds, respectively.

Speaker: Dr Deepak Deepak (Jülich Centre of Neutron Science at MLZ, Forschungszentrum Jülich GmbH)

Soft Matter: SM I

21 Welcome by Science Group

22 Dynamics of polymer and oleic acid in one component nanocomposites (OCNC)

OCNC made from polymer grafted nanoparticles are an advanced class of nanocomposites (NC). It circumvent the problem of segregation, commonly encountered in conventional NC. Grafting polymer chains on nanoparticles is an efficient method for synthesizing NC free from phase separation. The dynamics of grafted polymer chain is significantly influenced by the molecular weight (MW), temperature and the grafting density. We used a combination of QENS and BDS. We observe a MW dependent dynamics in grafted polymers. For lower MW, the dynamics of grafted polymer is decelerated as compared to the pure polymer. On the other hand, for higher MW, the dynamics of grafted chain is faster. We invoke a detailed analysis method using distribution of relaxation times to fit the data which unearths the presence of both faster and slower segments in OCNC. Our analysis reveals that the apparently different effect of grafting on the segmental dynamics of different MW grafted polymers is a consequence of different contributions from faster and slower segments. Broadly, we study the effects of grafting in different parts of the tethered chain using neutrons and other techniques.
We studied the dynamics of oleic acid in ungrafted and grafted state without any solvent using simplistic, yet physical, analytical approaches [3].
[1] Sharma, A. et al. Phys. Rev. Mater. 2022, 6 (1), L012601
[2] Sharma, A. et al. Macromolecules 2023, 56 (13), 4952–4965
[3] Sharma, A. et al. J. Chem. Phys. 2022, 150, 30401

Speaker: Margarita Kruteva

23 Structure of Single-Chain Nanoparticles Under Crowding Conditions: A Random Phase Approximation Approach

Macromolecules in biological systems in vivo are in the cell's crowded environment, which can modify biological function through changes in the structural conformation with respect to diluted conditions. The structural characterization in crowded media is challenging given the high concentration and the intrinsic complexity in these samples. To address the topological effects, we use model single-chain nanoparticles (SCNPs) —single-stranded polymers partially collapsed via intramolecular bonding. Neutron scattering is the best method to probe the structure of small concentrations of labeled chains in the presence of large concentrations of other species. Yet, at high concentration, even mild polymer-solvent interactions contribute to the scattering. To account for such effects, the Random Phase Approximation (RPA) formalism applies.
Here, we study with small angle neutron scattering (SANS) the conformation of poly methyl methacrylate (PMMA)-based SCNPs and linear precursors in dilute and in crowding with linear PMMA chains in deuterated dimethylformamide (DMF). The SANS profiles were analyzed in terms of a three-component (probe, crowder and solvent) RPA model to consider the polymer-solvent interactions. The presence of the crowder produces a size reduction on the probes. The Flory-Huggins interaction parameter varies with the sample composition indicating that in the dilute regime DMF is a good solvent for PMMA while in crowded conditions the polymer becomes less soluble.

Speaker: Beatriz Robles (Donostia International Physics Center (DIPC))

24 Interdiffusion of water in waterborne polymer latex films

Waterborne latex films, obtained from the dispersion of latex particles are of particular interest due to the non-content of volatile organic compounds (VOC), often mandatory under environmental legislation [1]. However, abrupt water penetration inside the films restricting their lifespan and deteriorating the shining of the coating. In order to prepare efficient and solvent-free coatings with the low glass-transition temperature (Tg < the drying temperature) but with higher mechanical strength, we have integrated hydrophilic layers (Acrylic acid/ Poly(acrylamide)) around the hydrophobic cores (mixture of Methyl methacrylate and Butyl acrylate) in the latex film. Latex particles with different morphology (hairy layer variants and core-shell particles) have been synthesized using emulsion polymerization. Polymer latex films have been prepared in the next step by evaporating water in a climate chamber at temperature 25 oC. The structure formation of polymer latex films in the dry state (crystallinity) and in re-swelled state (change in crystallinity and whitening or blushing) have been studied to propose a recipe for the preparation of efficient latex coatings. The combine study by SANS and SAXS show the FCC-like structure formation by the latex film, which become more organized with the inclusion of the that the hydrophilic shell.
1. I. Konko, S. Guriyanova, V. Boyko, L. Sun, D. Liu, B. Reck, Y. Men, Langmuir. 35 (2019) 6075.

Speaker: Debasish Saha (FZ Juelich)

Structure Research: SR I

25 Welcome by Science Group

26 Structural evolution of layered H2V3O8 high-capacity lithium storing cathode

V-based oxides are attracting much interest as promising next-generation electrodes due to the vast resources in the Earth's crust, their unique open structures for fast diffusion with outstanding electrochemical properties and various oxidation redox couples. A recent review has debated if they “will become the future choice for ion-metal batteries”.[1] H2V3O8 allows reversible two-electron transfer during electrochemical lithium cycling, yielding a high capacity of 378 mAh g–1. Aimed at providing insights into the lithium storage mechanism, we employed high-resolution synchrotron X-ray and neutron diffraction to accurately describe the crystal structures of both pristine and lithiated H2V3O8.[2] Easy hydrogen-bonding switch of structural water upon lithium intercalation not only allows better accommodation of intercalated lithium ions but also enhances Li-ion mobility in the crystal host, as evidenced by MAS-NMR spectroscopy. The hydrogen bonds mitigate the volume change of vanadium layers during Li de/intercalation, resulting in improved long-term structural stability. This study suggests that other hydrated oxides may be good candidates as electrode materials not only in implemented Li technology but also emerging rechargeable post-lithium metal-ion batteries.

1 D. Zhao, et al. ChemSusChem, 15, e202200479 (2022)
2 A. Kuhn, J. C. Pérez-Flores, J. Prado-Gonjal, E. Morán, M. Hoelzel, V. Díez-Gómez, I. Sobrados, J. Sanz, F. García-Alvarado, Chem. Mater., 34, 694-705 (2022)

Speaker: Alois Kuhn (Universidad CEU San Pablo)

27 Ultra-dense hydrogen stored in a metal hydride framework & investigated by Neutrons

Neutrons are a unique probe for non-destructive structural studies of energy materials, especially for the development of highly dense hydrogen stores. Thus, nano-porous materials have attracted great attention for gas storage, while the storage capacity still remains challenging. Here a magnesium borohydride framework with small pores was investigated and a unique partially negatively-charged non-flat interior for hydrogen and nitrogen uptake by using neutron powder diffraction, volumetric gas adsorption, inelastic neutron scattering. Hydrogen and nitrogen occupy distinctly different adsorption sites in the pores with very different limiting capacities: 2.33 H2 and 0.66 N2 per Mg(BH4)2. Molecular hydrogen is packed extremely dense with about twice the density of liquid hydrogen (144 g H2/L of pore volume), independently measured by three experimental methods. A penta-dihydrogen cluster is discovered where H2 molecules in one position have rotational freedom whereas in another have a well-defined orientation and a directional interaction with the framework. This study reveals that densely packed hydrogen can be stabilized in small-pore materials at ambient pressures.

Speaker: Prof. Michael Heere (TU Braunschweig)

28 Structural and electronic polymorphism in oxygen-doped Ruddlesden-Popper type oxides

Hole doped transition metal oxides have been extensively investigated due to their many active degrees of freedom such as charge, spin, and orbital ordering. An interesting alternative to metal substitution in nickelates, e.g., RE2-xSrxNiO4, is achieved by oxygen doping, yielding RE2NiO4+d. The extra oxygen atoms have been evidenced to be mobile down to ambient temperature, adding an extra complexity to the electronic ordering scenario by sub-mesoscopic oxygen ordering. Further on, the large-scale oxygen ordering can be easily switched with T and/or O-doping, adapting different 3D modulation vectors, all indicating well-defined lock-in phases. What is particularly challenging here is that phases with different modulation vectors, but invariant O-stoichiometry, can be obtained at RT, depending on their thermal history. It makes these phases to become a new playground to explore the evolution of charge and spin ordering schemes at constant O-stoichiometry. In this context, using polarized neutron scattering on IN12@ILL we could unambiguously evidence the key role interstitial oxygen atoms have for magnetic ordering and exchange paths in e.g. Pr2NiO4.23, where the c-axis of the magnetic structure is directly scaled with the modulation vector of the O-ordering. We’ll discuss the potential of these unexpected structure/property relations at constant stoichiometry for the tuning of electronic ordering phenomena for different oxides, explored with neutron and synchrotron scattering.

Speaker: Werner Paulus (Université de Montpellier, Sud de France)

14:30 Coffee beak

Material Science: MS II

29 Analysis of the influence of work hardening on the residual stress state in welded high-alloy steels using diffraction methods

Residual stresses can affect the behavior and performance of materials and components in many ways. While experimental methods can reliably yield the residual stress state resulting from welding, they are often costly and only deliver partial information. In contrast, numerical methods allow for an analysis at any specific point in space and time. However, the accuracy of such computations largely depends on the material model.

In welding simulation, modeling cyclic plasticity is of particular importance. Due to the inhomogeneous temperature field, the material near the molten zone experiences a plastic compression-tension cycle. Different assumptions on how to deal with the associated work hardening at reversal of loading significantly affect the numerical results, i.e. the local yield stress and thereby the distribution of the computed residual stresses. So far, comparisons of experimental and numerical analyses of residual stresses have yielded inconsistent results on the question which plasticity model should be used.

This work specifically addresses this deficit. Bead-on-plate weldments are analyzed by both in- and ex-situ diffraction methods. Thereby, not only the residual stresses are determined, but also microstructural hardening effects are characterized by diffraction line profile analysis. These results are used to evaluate different hardening models employed in finite element welding simulations.

Speaker: Nico Hempel (TUM)

30 Effects of Cross-Loading on the Material Behaviour

The prediction of material behavior following non-proportional load paths is still a major challenge in forming technology. In-situ synchrotron experiments are used to investigate the material behavior of a microalloyed and a dual-phase steel after different pre-strain levels and directional changes. It is shown that the material behavior is strongly dependent on the pre-forming level and the level of the change in the loading direction. Temperature-based methods can be used to determine the actual physical onset of flow. A significant change in the onset of flow as well as in the strain hardening behavior can be observed.

Speaker: Roman Norz (Lehrstuhl für Umformtechnik und Giessereiwesen)

31 Revealing the effect of hydrogen on CoNiCr-based superalloys by mechanical characterization, neutron and X-ray diffraction

Polycrystalline CoNiCr-based alloys show promising properties for future high temperature applications due to their potential to achieve a high y'-volume fraction while retaining a significant processing range. The growing importance on emission reduction through innovative propulsion technologies, such as hydrogen-based aviation fuels or water-enhanced turbofans, requires research into how hydrogen affects the strength and ductility of these alloys.
We conducted a comprehensive investigation into the effects of hydrogen exposure on the polycrystalline CoNiCr-based alloy CoWAlloy3 through a combination of ex-situ X-ray diffraction (XRD) laboratory measurements and neutron diffraction experiments. Our primary objective was to assess the impact of hydrogen on the lattice constants of both the y- and y'-phase. These findings were correlated with tensile tests to evaluate the occurrence of hydrogen-induced embrittlement.
Furthermore, we examined the fracture surfaces of the tested specimens using scanning electron microscopy (SEM) to discern variations in fracture behavior between the reference and hydrogen-exposed samples. Electron backscatter diffraction (EBSD) patterns were acquired at secondary cracks to ascertain whether transgranular or intergranular fracture behavior was present. This multidisciplinary approach allowed us to gain a comprehensive understanding of the hydrogen-related mechanical properties and fracture mechanisms in this alloy.

Speaker: Oliver Nagel (Friedrich-Alexander-Universität Erlangen-Nürnberg)

32 Rapid thermal cycling of perovskite solar cells

The increasing progress in developing next generation thin-film solar cells for space is shifting the focus of research towards practical implementation issues. Among the different types of next generation solar cells, in particular perovskite solar cells are gaining an increasing attention for space use. Meanwhile, first perovskite materials and devices have been tested in space. In contrast to terrestrial applications, solar cells in space are subject to extreme temperature fluctuations caused by rapidly alternating illumination and dark phases. In detail, they depend on the targeted mission. The thin-film architecture and, consequently, the low heat capacity per area of the devices additionally increase occurring temperature gradients and thereby add stress to the materials and devices.
Besides direct testing in space, also simulated space conditions tested on earth give valuable information. We investigate the effects of rapid temperature changes from 100 down to -196 °C on perovskite solar cells. The influence on the device performance is measured via IV measurements. Structural changes are characterized by SEM and X-ray diffraction measurements. Thus, the interplay between performance and micro- and meso-scale changes of the structure is gained, thereby providing further insights into the potential range of applications of perovskite solar cells in space.

Speaker: Simon Wegener (Technical University Munich Department E13)

Neutron Methods: NM II

33 Analysis of the noise limit in neutron dark field data

Neutron grating interferometry (nGI) allows simultaneous access to spatially resolved information about the attenuation, phase shift, and ultra-small-angle scattering (DFI) of neutrons in a sample by generating an interference pattern and analyzing the influence of the sample on the pattern.
Scattering decreases the visibility of the interference pattern. We can extract quantitative information about the scatterer by analyzing the visibility at different correlation lengths. However, the visibility may be reduced close to zero for strongly scattering samples. At the same time, the Poisson noise inherent in neutron detection generates a variation in the measured signal. The evaluation algorithm interprets this variation as finite visibility, limiting the minimum visibility accessible.
In our contribution, we will show how noise determines, dependent on neutron statistics, the minimum visibility. We will further show how these results may be used together with the reference visibility of the nGI setup to define a dynamic range of the DFI. Knowledge about the dynamic range allows one to plan measurement times more precisely.

Speaker: Tobias Neuwirth

34 Shape and size distribution of the magnetic domain structure in electrical steel measured with neutron grating interferometry

The magnetic flux guidance in an electric engine is achieved by introducing cutouts in the electrical steel (ES) sheets that make up its core. However, these cutouts create thin structures, reducing the mechanical strength of the ES sheets and limiting the achievable rotational speed and therefore the energy efficiency of the engine. We successfully created a novel type of magnetic flux barrier by introducing residual stress states in ES to reduce the local magnetic permeability. Such barriers show similar flux guidance as traditional barriers while the mechanical strength is comparable to unworked ES.

To prove the applicability of such magnetic flux barriers in future electric drives, and understand the changes to the local magnetic domain distribution, neutron grating interferometry (nGI) is applied to map ultra-small-angle neutron scattering off the magnetic domain structure in ES.

NGI probes the slit-smeared real space correlation function of the system at a specific correlation length.

In this presentation we will show the application of nGI to assess the structure size and shape of the magnetic domain structure in non-grain-oriented electrical steel by probing different correlation lengths and the anisotropy of the spatially resolved USANS signal recorded by nGI.

Speaker: Simon Sebold (MLZ)

35 HYMN – A novel unified toolbox for in-situ magnetic hyperthermia experiments using neutron scattering

One of the most promising use cases of magnetic hyperthermia is using magnetic nanoparticles (MNPs) for cancer therapy. In this treatment, MNPs are immersed into tumours and, by heating with external magnetic fields, typically 100-900 kHz, destroy cancer cells. For a successful application, the heating power needs to be improved by optimising the MNP structure. Recent studies have also shown a significant increase in magnetic heating by exciting the transversal spin modes in MNPs in the low GHz range. An ideal tool for characterising such MNPs is small-angle neutron scattering (SANS). Our ERUM-Pro HYMN project aims to develop a novel, unified experimental and computational toolbox for in-situ magnetic hyperthermia experiments under clinical conditions, utilising the SANS and MIEZE-SANS, combined with nanomagnetic simulations. This will be achieved by developing two setups for operation in the 100-450 kHz (up to 20 mT) and 0.5-4 GHz (up to 2 mT) range. We present the first SANS and SAXS results, where we used in-situ RF heating at up to 360 kHz to examine the dynamic structure formation of magnetite nanocubes with 12, 33, 35 and 53 nm sizes in water solutions. Our observations indicate the development of 1D and 2D structures, with significant variations linked to the field parameters and MNP sizes. We are currently conducting ongoing Reverse Monte Carlo simulations to further refine our interpretation of the obtained data.

Speaker: Michal Dembski-Villalta

36 A Markov Chain Monte Carlo approach to fit Molecular Dynamics simulations to neutron and X-ray diffraction and spectroscopy data on the example of water

Neutron and X-ray scattering experiments provide valuable insights into the nanoscopic properties of matter, a scale that is also accessible through Molecular Dynamics (MD) simulations. If the simulations reproduce the experiments, they can give greater insight into the material properties on the nanoscopic scale than traditional data analysis methods.
However, existing MD forcefields are primarily optimized to reproduce macroscopic quantities.
In our work we establish a connection between published experimental data from neutron and X-ray experiments on liquid water, specifically focusing on diffuse scattering and quasielastic neutron scattering, and MD simulations.
We integrate tools for MD simulation (LAMMPS) and scattering curve computation (Sassena) in a custom-built Bayesian framework that employs a Markov Chain Monte Carlo approach to sample parameter space. The fit algrorithm lets us obtain a set of parameters that capture the nanoscopic structure and dynamics as described by neutron and X-ray experiments simultaneously. Our approach explores a broad range within the parameter space, enhancing the likelihood of finding the global minimum of forcefield parameters.
This approach is highly versatile and can be adapted to different systems. Here, we utilize liquid water as a proof of concept for the workflow.

Speaker: Mrs Veronika Reich (GEMS at MLZ, Helmholtz-Zentrum Hereon)

Nuclear, Particle, and Astrophysics: NPA II - CLOSED SESSION

Positrons: e+ II

37 Proton Beam Based Production of a Positron Emitter by Exploiting the 27Al(p,x)22Na Reaction

$\beta^+$ emitters are essential for positron based defect spectroscopy experiments that require compact setups. In this thesis, weak $^{22}$Na positron sources have been produced by irradiating aluminum targets with a 68 MeV proton beam. This approach avoids wet chemical processes, which are used in commercial production of carrier-free $^{22}$Na positron sources. The design of the target allowed the production of multiple positron sources at once as well as the analysis of the depth dependent activity of $^{22}$Na, which was found to be in agreement with the simulated depth profile. In total a $^{22}$Na activity of 140 $\pm$ 5 kBq was produced, which is spread over 50 individual aluminum discs. The strongest positron source has an activity of 4.62 $\pm$ 0.23 kBq. This activity makes up about half of the activity typically used in Positron Annihilation Spectroscopy and can therefore be used for such measurements. The production of stronger sources is desired for such experiments and can easily be achieved by irradiating the target for a longer period of time. Other radionuclides among $^7$Be, $^{48}$Sc, $^{54}$Mn and $^{56}$Co were produced with a total activity of 70 $\pm$ 5 kBq. If required, the production, aside from $^7$Be, can be prevented by using aluminum of a higher purity.

Speaker: Lisa-Marie Krug

38 Positron trapping and annihilation in grain boundaries of µm and sub-µm grained polycrystalline materials

Structurally complex materials provide many different possible trapping sites for positrons. Especially, positron lifetime spectra of samples with µm and sub-µm sized grains must be carefully analysed, as positron trapping and annihilation in grain boundaries plays an increasingly important role and cannot be neglected anymore, even when other defect types are in the primary focus. To properly evaluate such multi-component spectra, the diffusion-reaction model for positron trapping and annihilation in grain boundaries [1-3] is extremely useful. In this contribution, the existing model is extended to competitive trapping at two different types of intragranular defects in addition to the grain boundary. Closed-form expressions for the mean positron lifetime and the relative intensities of the defect-specific positron lifetime components are given. This model provides the basis for the correct determination of defect concentrations, especially for the inconvenient but common case that one intragranular defect type exhibits a lifetime component similar to that in grain boundaries. If in such a case one would not consider the grain boundary as positron trap, the determined intragranular defect concentration would be overestimated strongly even for µm-sized crystallites.

[1] R. Würschum and A. Seeger, Philos. Mag., 73, 1489 (1996)
[2] J. Dryzek, A. Czapla and E. Kusior, J. Phys. Condens. Matter, 10, 10827 (1998)
[3] B. Oberdorfer and R. Würschum, Phys. Rev. B, 79, 184103 (2009)

Speaker: Mr Philipp Brunner (Institute of Materials Physics, Graz University of Technology)

39 Vacancy Defects in Photovoltaic Antimony Selenide

Antimony selenide (Sb$_2$Se$_3$) is photovoltaic material with an optimal bandgap and a high optical absorption coefficient comprising of earth abundant elements. Solar cell power conversion efficiencies initially increased markedly but more recently the rate of increase has slowed. There is a large open circuit voltage consistent with the presence of detrimental concentrations of point defects. Here we report the results of variable energy positron annihilation lifetime measurements and related density functional theory calculations of positron lifetimes. Measurements have been performed on a series of closed-space sublimation deposited films and a range of single crystal samples including stochiometric with and without post-growth annealing, oxygen-doped and Sn-doped samples. The results provide evidence for the presence of both monovacancy and divacancy defects. The high implantation energy results from stoichiometric crystal grown from high purity stock and the CSS films subjected to a post-growth anneal exhibited spectra dominated by perfect lattice annihilations.

Speaker: David Keeble (University of Dundee)

40 Correlation of Mechanical Stress and the Positron Lifetime in Aluminum Alloys

Positron annihilation lifetime spectroscopy (PALS) is a sensitive technique to analyze the type and concentration of lattice defects on an atomic level.
We applied ex-situ PALS to plastically deformed technical Al and Al alloys.
We measured the depth-dependent positron lifetime at the accelerator-based positron source MEPS at ELBE.
For each sample we recorded the tensile stress, and the corresponding stress-strain curves.
This allows us to determine the relation between applied stress, strain and mean positron lifetime.
Thereby we are able to observe the creation and evolution of stress-induced defects in the region beyond the elastic Hook regime of the specimen.
Within this contribution, we also discuss the evolution of the defect population with increasing deformation by examining the intensity change of the different positron lifetime components found in the PALS spectra.

Speaker: Lucian Mathes

Quantum Phenomena: QP II

41 Magnetic phase transitions of an incommensurate Dzyaloshinskii-Moriya antiferromagnet with effective 2D interactions

Using neutron diffraction, the magnetic fluctuations are investigated near the phase transition to a long-range ordered incommensurate cycloid spin spiral in the antiferromagnetic insulator Ba2CuGe2O7. We find that these fluctuations possess a two-dimensional character and, as a consequence, cover an extended cylindrical manifold in reciprocal space. Their distribution can be explained with a ratio of in- and out-of-plane stiffness of 0.027, in agreement with previous reports. The temperature dependence of the correlation length is consistent with a crossover from 2D antiferromagnetic Heisenberg fluctuations to incommensurate fluctuations with decreasing temperature, highlighting the plethora of phase transitions associated with spiral magnetic textures.
Recently, a new phase with a vortex-antivortex magnetic structure has been theoretically described. It has been experimentally confirmed in a pocket in the phase diagram at around 2.4K and an external field along the crystalline c-axis of around 2.2T. A lack of evidence for a thermodynamic phase transition towards the paramagnet in high resolution specific heat measurements and a finite linewidth in energy and momentum of the incommensurate peaks in neutron scattering, as opposed to the cycloidal ground state, seem to mark the vortex phase as a slowly fluctuating structure at the verge of ordering.

Speaker: Peter Wild

42 Complex magnetic orders and the emergent topological Hall effect in the kagome metal ErMn6Sn6

Following the discovery of a quantum-limit magnetic Chern phase in TbMn6Sn6, and the observation of a large topological Hall effect (THE) related to the field-induced magnetic phases in YMn6Sn6, the magnetic topological metal series RMn6Sn6 (R=Gd-Yb, and Y, Lu), that possess an ideal kagome lattice of Mn, have emerged as a new platform to explore exotic states and novel functionalities. We have recently carried out the growth of high-quality single crystals of the magnetic kagome metal ErMn6Sn6 via the flux method, and the physical properties characterizations via the magnetic susceptibility, heat capacity, and Hall conductivity measurements. We have also undertaken comprehensive neutron diffraction experiments on both single-crystal and powder samples at the WISH diffractometer at ISIS. Several distinct magnetic ordered phases, including the spiral, conical, and k = 0 magnetic orders, have been identified in cooling to low temperatures. Furthermore, we have also observed a range of complex field-induced magnetic phases, including the multi-k non-coplanar magnetic orders, via field-dependent single-crystal neutron diffraction at WISH. We have found that these complex field-induced magnetic phases are directly associated with our observed THE over a wide phase space of field and temperature in this compound. Our study has hinted at a fascinating interplay between topologically non-trivial electronic band structures, magnetism, and electronic correlations in ErMn6Sn6.

Speaker: Yishui Zhou

43 Spin excitations in the two dimensional antiferromagnet Na2BaMn(PO4)2

The study of geometrically frustrated systems with antiferromagnetically ordered spins on a two-dimensional lattice has recently gained considerable attention for their exotic quantum magnetic properties. In order to explore effects related to quantum magnetism we recently focused our attention to Na2BaMn(PO4)2. So far previous works on the isostructural Na2BaCo(PO4)2, a Co spin-1/2 compound [1], and on the Na2BaNi(PO4)2, a Ni spin-1 compound [2], have showcased intriguing phenomena close to quantum criticality.
Using inelastic neutron scattering measurements performed at a cold triple axis spectrometer we determine the magnetic propagation vector and the low energy spin excitations of Na2BaMn(PO4)2 at mK temperatures. We compare our results with the Co and Ni counterparts and we find similarities not only in the temperature- magnetic field (H-T) phase diagrams, but also in the spin excitation spectra.

[1] J. Sheng et al., Proc. Natl. Acad. Sci. U.S.A. 119, 51 e2211193119 (2022).
[2] Jieming Sheng, et al. arxiv:2306.09695 (2023).

Speaker: Dr Nikolaos Biniskos (Charles University, Faculty of Mathematics and Physics, Department of Condensed Matter Physics, Ke Karlovu 5, 121 16 Praha, Czech Republic)

44 Field-Dependent Magnetic Ordering Dome and Quantum Spin Fluctuations in the Natural Mineral Henmilite

Quantum materials have been playing a crucial role in the development of next-generation technologies and devices, including quantum computers. Such materials are usually prepared under laboratory conditions. However, some naturally occurring minerals have also been found to feature complex magnetic ground states, such as Henmilite [1] or Herbertsmithite [5,6]. They possess spin ½ Cu ions, which exhibit a magnetic ground state favouring the creation of quantum fluctuations, hinting at a possible quantum spin liquid state [1].
Henmilite is a bright blue-violet colour mineral, which has been suggested to consist of coupled two-leg ladders, where strong quantum fluctuations suppress (AF) magnetic order at low temperatures [1]. It is an extremely rare mineral only found in the Fuka mines of Japan [3]. In Henmilite, the B-T phase diagram has an unusual antiferromagnetic dome [2]. The nuclear crystal structure is complex and contains well-separated sheets of Cu(OH)4 square-planar plaquettes, separated by a network of Ca(OH)8 and B(OH)4 polyhedra. DFT (GGA+U) calculations found interlayer magnetic coupling less than 1% of the dominant intra-plane coupling, confirming the magnetic 2D nature of the material [1].

We will present our experimental results of the specific heat and magnetisation measurements on a single-crystal Henmilite.

References
[1] Hajime Yamamoto et al., PRM 5, 104405 (2021)
[2] Braithwaite et al., Mineralogical magazine 68.3 (2004): 527-539.
[3] Izumi Nakai et al., American Mineralogist 1986; 71 (9-10): 1234–1236.
[4] https://mambaproject.cz/alsa
[5] D. S. Inosov, Advances in Physics, 67:3, 149-252 (2018)
[6] R. S. W. Braithwaite et al., Mineralogical magazine 68.3 (2004): 527-539.

Speaker: Mr Ankit Labh (Charles University)

Soft Matter: SM II

45 Injectable hydrogels from thermoresponsive tri- and tetrablock terpolymers investigated using scattering methods

Thermogels are an exciting class of stimuli-responsive materials with many promising applications ranging from the medical field to additive manufacturing. The mechanical properties in the gel state strongly depend on the architecture of the polymer [1].
Here we address an ABC triblock terpolymer and a BABC tetrablock terpolymer consisting of the hydrophilic oligo(ethylene glycol) methyl ether methacrylate (OEGMA, A), the hydrophobic n-butyl methacrylate (BuMA, B), and the thermoresponsive di(ethylene glycol) methyl ether methacrylate (DEGMA, C). The results from dynamic light scattering (DLS) on dilute solutions indicate that the hydrodynamic radii of the micelles formed by both, ABC and BABC, increase strongly above 25 °C, and the solutions feature a cloud point, i.e. aggregation of the micelles sets in. By synchrotron small-angle X-ray and neutron scattering (SAXS/SANS), we found that the triblock terpolymers ABC form spherical core-shell micelles, that transform into cylinders at high temperatures. In contrast, the core-shell micelles formed by the BABC tetrablock terpolymers stay spherical and form small fractal aggregates at higher temperatures, that become more compact upon further heating.

[1] A. P. Constantinou, B. Zhan et al., Macromolecules, 2021, 54, 1943.

Speaker: Ms Feifei Zheng (Technical University of Munich)

46 Smart Microgel Based Membranes for Electrochemical Devices and Catalysis

Smart copolymer microgels based on acrylamides are promising for several applications [1,2] Therefore these systems are intensely studied in recent years. If microgels are made with (photo-)crosslinkable comonomers (secondary crosslinkers), they can be deposited in thin layers and subsequently be cross-linked by irradiation [3,4]. Upon cross-linking freestanding membranes are obtained, which still exhibit the volume phase transition (VPT) of the microgels. The present contribution describes the investigation of such microgels by small angle scattering and also the membrane formation.
The VPT of the obtained 2D materials can be exploited to make membranes which modulate ion flow by changing temperature. This can be used in electrochemical devices. The resistance is found to steeply increase by up to an order of magnitude at the VPT of the original microgels. Hence, these freestanding microgel membranes might be useful for building self-regulating fuel cells. Moreover, they can be doped with metal nanoparticles granting them catalytic activity and allowing to use them in flow reactors or microfluidic cells for chemical conversion [5].

References
[1]M. Karg, et al., Langmuir 2019, 35, 6231-6255.
[2] M. Flechter, et al., Biotechnology and Bioengineering 2022, 119, 1728-1739.
[3] M. Dirksen, et al., Langmuir 2022, 38, 638-651.
[4] J. Bookhold, et al., Soft Matter, 2021, 17, 2205-2214.
[5]V. Sabadasch, et al., ACS Applied Materials & Interfaces , 2022, 14, 43, 49181–49188.

Speaker: Thomas Hellweg (Universität Bielefeld, PCIII)

47 Investigation of solvent uptake of salt containing PNIPMAM thin films

Stimuli responsive polymers gained lot of attention in the past due to their unique properties. If polymer thin films exhibit a reversible volume change upon exposure to external stimuli such as temperature, light, pH, or solvents, they become promising candidates for applications such as nanoswitches or sensors. Poly(N-isopropyl methacrylamide) (PNIPMAM) is a lower critical solution temperature (LCST) type thermoresponsive polymer with a LCST in water at around 44°C and is able to absorb water molecules when it is exposed to water rich atmospheres. Due to low swelling times and strong volume changes upon water incorporation PNIPMAM thin films are of special interest. In this work, the influence of different salts on the swelling behavior of PNIPMAM thin films is explored. In situ time-of-flight neutron reflectometry measurements are performed to investigate the macroscopic swelling behavior of the salt containing polymer thin films. By fitting the obtained reflectivity patterns, information about the distribution of the compounds vertically through the thin films can be deduced. To gain further insights on a molecular level and to understand the underlying hydration mechanism, additional in situ Fourier-transform infrared spectroscopy measurements are performed. Our studies showed, that the addition of different salts highly influences the swelling behavior as well as the hydration mechanism of PNIPMAM thin films depending on the salt additive.

Speaker: Julija Reitenbach

48 Pressure effect on protein cluster formation induced by multivalent ions

A thorough understanding of protein interactions in aqueous solutions is crucial for many areas of research in soft matter and biology. For example, a strong interprotein attraction can lead to protein aggregation, which is observed in several pathologies such as cataract and neurodegenerative diseases.
We have shown that a patchy particle model can describe the phase behavior of a system of acidic globular proteins such as bovine serum albumin in the presence of multivalent salts such as yttrium chloride. The phase diagram of the studied system as a function of salt concentration and temperature is quite complex, showing reentrant condensation, metastable liquid-liquid phase separation, cluster formation and crystallization. In particular, a lower critical solution temperature is observed which suggests that hydration plays an essential role in the ion-mediated protein interactions.
Here we will present results from pressure dependent neutron spectroscopy experiments. In contrast to the previous studies at and above room temperature we found, that the slowing down of the short-time self-diffusion is less pronounced. This behavior of the short-time self-diffusion will be discussed with the help of pressure dependant SAXS measurements.

Speaker: Marcell Wolf (TUM)

Structure Research: SR II

49 STRUCTURAL STUDIES ON TWO-DIMENSIONAL SODIUM OXIDES AS CATHODES FOR NA-ION BATTERIES

Increased attention to sodium-containing materials during the last years is caused by the rapid development of sodium-ion batteries (NIBs), which are considered as a potential successor for lithium-ion batteries (LIBs). Especially layered sodium oxides with transition metals have gained large interest due to their potential applicability as cathode materials. Similar to LiCoO2 in LIBs, NaCoO2 of the α-NaFeO2 or β-RbScO2 structure type shows an immense potential as a cathode in NIBs. A partial replacement of Co by other redox-active (Ni, Mn, Fe) or inert (Mg, Ti, Sb) metal cations can stabilize the crystal structure during (de)sodiation, and reduce the number of phase transformations. Other class of layered Na-oxides with a MnO2·nH2O birnessite-type structure, also suitable for application as Na-cathodes, is much less investigated, probably due to a difficulty to obtain a water-free materials. Here Mn cations can be partially replaced by other transition metals, while Na-cations can replace H2O molecules.

Using neutron powder diffraction, we investigated temperature-dependent structural behavior of layered Co-oxides of different structure types in order to optimize the synthesis conditions. Using operando synchrotron diffraction and X-ray absorption spectroscopy, we studied their structural evolution in Na-batteries during charge and discharge. The combination of structural studies facilitated understanding the electrochemical performance of the materials.

Speaker: Daria Mikhailova (IFW Dresden)

50 Influence of Structure and Charge Ordering in P2-type Cathode Materials for Sodium-ion Batteries

With increasing share of energy generation from renewables, intermittent electrical energy storage is gaining significance. Sodium-ion batteries (SIB) are currently developed and commercialized as cost-effective complementary technology to today’s Lithium-ion batteries (LIB). For SIBs, P2-type layered oxides are considered amongst the most attractive cathode active materials.
In this work, we have synthesized P2-type NaxMnyNi1-yO2 cathode active materials for SIBs with y = 2/3 and 3/4. The materials are characterized with Neutron and X-ray powder diffraction and advanced electrochemical methods. The material with y = 2/3 exhibits a honeycomb Ni/Mn superstructure and clear potential jumps at distinct sodium contents (x = 2/3, 1/2, 1/3). Based on electrochemical investigations and operando Synchrotron XRD, these voltage jumps are assigned to Na+/vacancy orderings. With increased Mn-content of y = 3/4, the honeycomb Ni/Mn superstructure is disrupted, the potential profile smoothed and the extend of Na+/vacancy orderings reduced. Using first principle calculations (DFT), we demonstrate, that Na+/vacancy ordering is directly related to charge ordering within the transition metal slab. The influence of transition metal charge ordering on Na+/vacancy ordering is discussed and validated against P2-type cathode materials with various transition metal compositions. A general guideline to suppress Na+/vacancy orderings in P2-type cathode materials for SIBs is postulated.

Speaker: Lukas Pfeiffer (Zentrum für Sonnenenergie- und Wasserstoff-Forschung BW)

51 Science case and concepts of a macromolecular diffractometer for the High Brilliance Neutron Source (HBS)

Enzymes are a sub class of proteins which act as natural catalysts and reduce the activation energy of chemical reactions necessary to keep up the metabolism of life. This renders enzymes important drug targets. To elucidate their structure is often the key to understand certain diseases. X-ray protein crystallography contributed by far the largest number of structures but methods like transmission electron microscopy start to yield also atomic resolution. However, those techniques lack the ability to locate hydrogen atom positions since they scatter from the electron shells. Hydrogen has only one electron and is therefore a weak scatterer for electrons or x-rays but it often plays a crucial role in the enzymatic process. Here, neutrons provide a solution since they scatter from the nuclei. Neutron protein crystallography is now an established technique and has elucidated many enzymatic processes by pointing out important protonation states of amino acid side chains. But it requires a large neutron flux and good resolution in reciprocal space. Therefore, the number of instruments accessible to the user community is limited. Mostly, these instruments reside at powerful reactor or spallation neutron sources. In this contribution we would like to asses how one can design such an instrument at a High current proton accelerator-based Neutron source (HiCANS). Using Vitesse simulations on potential instruments we discuss their potential for the future user community.

Speaker: Tobias Schrader

52 Monoclinic symmetry of the hcp-type ordered areas in bulk cobalt

The gradual ferromagnetic spin reorientation in the hcp phase of cobalt between 230 °C and 330 °C reported for a Co single crystal [1] suggests that this phase cannot have a hexagonal symmetry [2,3]. This hypothesis is verified positively by synchrotron radiation diffraction (MSPD@ALBA) and neutron diffraction (SPODI@MLZ and D2B@ILL) on the powder of cobalt [3]. The analysis of diffraction data has been done by using a specific set of Bragg peaks, which are not affected by the stacking faults present in abundance in hcp-Co [1,4]. The crystal structure of the hcp-type ordered areas of cobalt is described by a monoclinic symmetry with the magnetic space group C2'/m', where the former hexagonal [001] axis is no longer perpendicular to the hexagonal layers. The hexagonal [001] and [010] axes make an angle equal α ≈ 90.10(1)°, while the angle between in-plane [100] and [010] axes equals γ ≈ 120.11(1)°. The monoclinic symmetry provides an approximate description of the crystal structure of the stacking faulted hcp-Co areas coexisting with fcc-Co areas [3].
[1] E. Bertaut, A. Delapalme & R. Pauthenet, Solid State Commun. 1 (1963) 81
[2] P. Fabrykiewicz, R. Przeniosło & I. Sosnowska, Acta Cryst. A77 (2021) 327
[3] P. Kozłowski, P. Fabrykiewicz, I. Sosnowska, F. Fauth, A. Senyshyn, E. Suard, D. Oleszak & R. Przeniosło, Phys Rev. B107 (2023) 104104
[4] O. Blaschko, G. Krexner, J. Pleschiutschnig, G. Ernst, C. Hitzenberger, H. P. Karnthaler & A. Korner, Phys. Rev. Lett. 60 (1988) 2800

Speaker: Piotr Fabrykiewicz (Institute of Crystallography, RWTH Aachen University, Germany and Jülich Centre for Neutron Science (JCNS) at Heinz Maier-Leibnitz Zentrum (MLZ), Forschungszentrum Jülich GmbH, Garching, Germany)

16:40 Coffee break

Material Science: MS III

53 Ammonia Sorbents for Novel Ammonia Synthesis Routes studied using in situ neutron imaging

In 2021, ammonia was second most produced chemical in the world. Among different ammonia synthesis routes, the most prevalent is the Haber-Bosch process. However, it has been recently demonstrated that with new types of catalysts, ammonia can be synthesized at lower pressures and temperatures. To unlock the potential of this mild condition ammonia synthesis, it is necessary to find an alternative to ammonia condensation. A promising solution is ammonia absorption by metal halides, as these materials can efficiently and selectively remove ammonia down to ppm level, even at elevated temperatures. Within the framework of the ARENHA project (Horizon 2020, No 862482), we develop manganese chloride-silica gel sorbents to promote novel ammonia production paths.
In this work, the manganese chloride–silica gel sorbents were studied using in-situ radiography at the NEUTRA beamline (SINQ, PSI). Two-dimensional neutron radiography images of the sorbent bed were taken during breakthrough tests, during which a gaseous mixture of ammonia and nitrogen was passed through the bed at a controlled flowrate. During the tests, we could observe ammonia uptake and release within the sorbents. The results of the image analysis are discussed with respect to the homogeneity of the ammonia sorption over the volume of the reactive bed and how it is affected by manganese chloride loading in the sorbents.
Changes in the sorbent bed dimensions and sorbent morphology during cycling are also reported.

Speaker: Richi Kumar

54 Small Angle Neutron Scattering data driven simulation of chemical diffusion of hydrogen in metal hydrides

Human civilization is expected to face a huge challenge in the form of climate change in this century. One of the factors affecting this change is the use of fossil fuels, which have to be supplanted by so-called ’renewable energy sources’. Hydrogen is one of many possibilities for this energy storage, but a potent solution for storing the hydrogen is still being explored [1].

In this project, metal hydrides were investigated at the nanoscopic level as a solution for hydrogen storage materials. Our system contains a mixture of MgNH2, LiBH4, and LiH, and Small Angle Neutron Scattering (SANS) measurements were performed to investigate the absorption and desorption of hydrogen [2].

This work tries to explain the SANS data using a simulation driven by the experimentally measured data. The approach mainly targets solving the reverse problem, i.e. the inference of the real-space structure from scattering data. The reverse problem is under-determined due to the phase problem; in this particular case, several boundary conditions are known from the experiment that help to find a solution when incorporated into a physically sound simulation. Initially, diffusion within a single grain is simulated using generated experimental data, which is followed by its application to the real situation, i.e. simulation of diffusion, driven by acquired experimental data, with multiple grains.

References
[1] Pistidda et al., doi: 10.3390/hydrogen2040024.
[2] Aslan et al., doi:10.3233/JNR-190116

Speaker: Arnab Majumdar (Helmholtz Zentrum hereon)

Neutron Methods: NM III

55 Development of a Nested Mirror Optic Array for the Thermal TAS PUMA

A persistent challenge for the inelastic neutron scattering technique has been the low scattering cross-section of neutrons, necessitating large sample sizes compared to other techniques. Focusing the neutron beam is a viable technique to increase the flux reaching the sample, but previous techniques suffer from limitations to beam size and quality or an excessively close distance to the sample which interferes with sample environments. The nested mirror optic (NMO) is an ideal solution to overcome these challenges and provide a small, well-behaved beam at the sample position while maintaining space for sample environment equipment. The development of supermirror coatings with large m-values has opened up the possibility to apply this technique to the thermal TAS instrument PUMA at MLZ. While current focusing techniques on PUMA yield a cross section of 20mm x 20mm, the current NMO project seeks to develop, install and commission an NMO setup that will reduce the beam size to 5mm x 5mm while preserving 50% of the incoming neutrons, for an 8-fold increase in flux on small samples. It will do this while also providing space for the sample environment and preserving the beam characteristics, and will be straightforward to mount and dismount to adjust for the needs of each user. I will discuss the planned setup and our current progress in designing the NMO setup for PUMA, as well as the scientific case for such a device with several planned use cases.

Speaker: Dr Adrian Merritt (Karlsruher Institut für Technologie)

56 Development of low-depolarizing CuTi neutron supermirrors

Neutron supermirrors are multilayer structures of varying bilayer thickness with the purpose of extending the critical angle of the coating, increasing the neutron flux reaching the neutron instruments. The sputtered layers of the supermirrors are mostly made of nickel and titanium due to their excellent scattering contrast. Depolarization effects due to the ferromagnetism of nickel are routinely suppressed to well below 1% by molybdenum alloying. However, a new generation of instruments measuring the angular correlation coefficients in ß-decay of free polarized neutrons require neutron guides exhibiting depolarization below 10-3.

In the last years the neutron optics group of FRM II has successfully sputtered a 190-layer non-depolarizing m=2 CuTi supermirror produced by standard DC magnetron sputtering. Control of the roughness growth and interdiffusion allowed us to get a maximum angle of total reflection of 0.21°/λ and polarized neutron reflectivity above 90%, as measured at the instrument GINA (BNC). The CuTi coating was checked by means of SQUID measurements at the WMI (Garching) to be slightly ferromagnetic with magnetic moment of 2×10-3 emu/cm3, compared to 500 emu/cm3 of NiTi and 0.1 emu/cm3 of Ni(Mo)Ti supermirrors.

Recent depolarization measurements performed at the PF1B beamline (ILL) using the Opaque Test Bench setup excluded depolarization of a fully polarized neutron beam after a reflection on the CuTi supermirror in the range of 10-4.

Speaker: Dr Jose Manuel Gomez Guzman (Technische Universität München Heinz Maier-Leibnitz Zentrum (MLZ))

Nuclear, Particle, and Astrophysics: NPA III - CLOSED SESSION

Positrons: e+ III

57 Sodium Source Based Measurements at the CDBS in Between Reactor Cycles

The Coincidence Doppler Broadening Spectrometer (CDBS) at the NEutron induced POsitron source MUniCh (NEPOMUC) uses positrons as a microprobe to investigate material defects on an atomic level. The instrument can give insights into open volume defect concentrations in samples. However, additionally, by utilizing the coincidence feature and advanced evaluation software the chemical environment around the positrons annihilation site can be investigated. During the reactor shutdown the instrument has used a 22Na source to perform bulk measurements. The findings of several studies on AlCu alloys, as well as high statistics measurements will be shown. The latter gives a better insight into the behavior of the positron in bulk materials, specifically the thermalization process.

Speaker: Leon Chryssos

58 Spatially Resolved and Element-Sensitive Defect Analysis with Positrons

The Coincidence Doppler Broadening (CDB) spectrometer with its monoenergetic scanning positron beam allows the investigation of defect distributions in three dimensions (3D) and the elemental surrounding of open-volume defects. With thsi instrument we address the following scientific questions: Homogeneity of samples, i.e. depth and lateral distribution of lattice defects. Examples are (laser beam or friction stir) welded technical alloys, irradiated materials, superconducting and (doped) thin semiconducting films; defect kinetics and fast defect annealing at high temperatures, e.g. of samples after severe plastic deformation or plasma-facing materials for fusion reactors; vacancy-solute complexes and nano-clusters in, e.g. doped semiconductors or precipitation-hardened alloys; in-operando defect analysis of samples, which are not stable in vacuum, exposed to gases and/or during application of el. fields. Examples are electrode materials or aging of thin polymer films in various atmospheres; fundamental research with otho-Positronium (o-Ps).
Wihtin this presentaiotn we discuss potential upgrades of the CDB spectrometer in terms of (i) spatial resolution, (ii) measurement time , and (iii) high sample temperature.

Speaker: Christoph Hugenschmidt

Quantum Phenomena: QP III

59 Room Temperature Skyrmions in Pt/Co/Ta Multilayers

Magnetic skyrmions are topologically stabilized spin configurations on the nanoscale which makes them promising for next-generation information storage technologies and computing. [1,2] In magnetic multilayers, they can be stabilized at room temperature [3]. Skyrmions emerge due to an interplay between several magnetic contributions. Among them the interfacial Dzyaloshinskii-Moriya Interaction (DMI) drives the spins into non-collinear orientation, while the perpendicular magnetic anisotropy (PMA) favours the out-of-plane orientation and the shape anisotropy prefers in-plane spin orientation.
Polycrystalline [Pt(40 Å)/Co(x)/Ta(19 Å)]$_N$ multilayers were fabricated in a molecular beam epitaxy setup by thermal deposition on oxidized Si(001) substrates with a buffer layer of 47 Å Ta and a 30 Å Pt cap layer. The Co film thickness was varied between 5 Å and 21 Å, the number of repetitions varied between 8 and 10. Magnetic force microscopy measurements reveal the existence of skyrmions at a Co thickness between 9 Å and 17 Å. We discuss results obtained from magnetic hysteresis, transport and neutron reflectometry measurements. The latter have been performed with the neutron reflectometer Platypus at ANSTO, Australia.

References
[1] A. Fert, V. Cros, and J. Sampaio,  Nature Nanotech 8, (2013) 152. 
[2] K. Raab, M.A. Brems, G. Beneke, et al., Nat Commun 13, (2022) 6982. 
[3] S. Woo, K. Litzius, B. Krüger, M.-Y. Im, L. Caretta, K. Richter et al., Nat. Mat. 15 (2016) 501

Speaker: Dr Sabine Pütter (Jülich Centre for Neutron Science JCNS at MLZ, Forschungszentrum Jülich GmbH)

60 Topotactic hydrogen in LaNiO3-xHy thin films studied by neutron reflectometry

The modification of epitaxial layers through hydrogenation is a thriving field of research that offers diverse opportunities to tune the physical properties of different systems. Recent research has been extended to correlated oxide interfaces, where hydrogen induced, reversible metal-to-insulator transitions have been uncovered in material systems such as rare-earth nickelates [1-2]. Neutron scattering methods are without doubt one of the best way to study these systems. In this talk we will show the results of the first neutron reflectometry (NR) study of in situ hydrogen exposure of LaNiO$_{3}$ to hydrogen gas. In particular the combined use of deuterium and hydrogen allowed us to distinguish and quantify oxygen depletion and hydrogen incorporation, which are two possible mechanisms to explain the electronic modification of the host layer. In addition to the neutron measurements, we will show other complementary techniques used to understand the incorporation phenomena, including electrical transport and x-ray methods.

References
[1] J. Shi, Y. Zhou, S. Ramanathan, Nat. Commun. 2014, 5, 4860.
[2] Haowen Chen, et al. Nano Letters 2022 22 (22), 8983-8990

Speaker: Laura Guasco

Soft Matter: SM III

61 On the structure and function of lipid nanoparticles for delivery of bioactive molecules

Non-lamellar lipid aqueous phases, such as reverse cubic or hexagonal phases, have increasingly been used to entrap biomolecules. We here discuss encapsulation of two key types of enzymes of different sizes, namely Aspartic protease (34 KDa), Beta-galactosidase (460 KDa) as well as heme proteins of importance for e.g. food iron supply. Although the curvature of the lipid aqueous interfaces in these phases determines the size of the aqueous cavities and hence the space given to the enzyme, the interaction between the enzyme and the lipid layer is an important factor that controls the efficiency of the encapsulation. We used mixtures of acylglycerides and acyldiglycerides, which can form highly swollen sponge phases (L3), with aqueous pores up to 13 nm of diameter and with the help of the dispersing agent polysorbate 80 (P80) they form well defined nanoparticles in excess water.Size exclusion chromatography show efficient encapsulation of both enzymes, yet they retained their enzymatic activity over months, surpassing the storage stability of pure enzymes in solution. The reason for this can be understood in terms penetration of the enzymes into the formed lipid bilayer as shown by Raman spectroscopy and neutron reflectometry on supported lipid bilayer of same composition. This has been confirmed by neutron spin echo and molecular dynamics simulations.

Speaker: Tommy Nylander (Lund University)

62 Neutrons and Light as tools for the identification of specific biorecognition molecules for LPS detection.

Gram(-) bacteria are pathogenic microorganisms whose outer membrane of the external envelope is composed of lipopolysaccharides (LPS), consisting of three structural domains: lipid A, the core oligosaccharide, and the O antigen. They are endotoxins responsible for many infections induced by bacterial pathogens, so represent a suitable target for selective detection. This can be achieved through specifically designed biosensors, where the biorecognition event is exploited for detection. Among biorecognition molecules, aptamers are very appealing. They are single-stranded DNA or RNA with high affinity and specificity towards specific analytes. Recently, an aptamer named LA27 has been identified to selectively recognise LPS. The LPS portion interacting with LA27 is not well understood yet. However, preliminary studies suggest a direct affinity with lipid A as well as a capability of this aptamer to interact with LPS deriving from different strains of Gram(-) bacteria.
In this study, we investigated the interaction of LA27 with two LOS and one LPS extracted respectively from three Gram(-) strains: Akkermansia, Flavobacterium and Paenalcaligenes hominis. Exploiting Neutron Reflectometry and Dynamic Light Scattering on biomimicking bacterial membranes we were able to see that LA27 can interact with both LOS and LPS, although with Los a higher affinity was detected. The analysis of the experimental result suggests that the interaction is ruled by the O-antigen region of the LPS.

Speaker: Alessandro Cangiano (University of Naples Federico II - CSGI)

Structure Research: SR III

63 A2Ir2O7 rare-earth pyrochlore oxides under extreme conditions

$A_2B_2O_7$ oxides gathered considerable attention due to many complex and exotic (ground) states observed or theoretically predicted, e.g., spin liquid, spin ice, topological insulator or Weyl semimetal [1,2]. Geometrical frustration of magnetic moments, responsible for these states, is defined very well in $A_2Ir_2O_7$ iridates (with A being the rare earth) since they crystallize in the ordered pyrochlore structure for all rare-earth analogues. With this cubic structure (space group Fd-3m), two sublattices of corner-sharing tetrahedra for both $A^{3+}$ and $Ir^{4+}$ magnetic ions are present in A2Ir2O7 iridates, which are moreover surrounded by 8 and 6 oxygen ions, respectively. In this study, we present high-pressure and low-temperature characterization of selected $A_2Ir_2O_7$ analogues, focusing more on the less-investigated heavy-rare-earth side of the periodic table. Polycrystalline samples were grown by the CsCl flux method. Thermal and pressure compressibilities, including detailed insight into oxygen cage deformation of the pyrochlore lattice, are presented and discussed together with other phenomena like metal-insulator transition or the antiferromagnetic all-in-all-out ordering or $Ir^{4+}$ sublattice [3].
[1] E. Lefrançois et al., Nat. Commun. 8, 209 (2017).
[2] W. Witczak-Krempa et al., Annu. Rev. Condens. Matter Phys. 5, 57-82 (2014).
[3] D.Staško et al., J. Phys. Chem. Solids 176, 111268 (2023).

Speaker: Daniel Staško (Charles university, Department of condensed matter physics)

64 Neutron scattering of the easy-plane magnet ErB2

We present neutron scattering data on the hexagonal rare-earth diboride ErB$_2$. ErB$_2$ orders magnetically below T$_c$ = 14 K, where the magnetocrystalline anisotropy shows strong easy-plane characteristics, as established from measurements of the specific heat, ac susceptibility, magnetisation and electrical transport.

In order to investigate the magnetic structure we performed single-crystal neutron diffraction in zero and finite field as a function of temperature. We have also performed inelastic neutron scattering measurements, parts of which were done with the artificial intelligence assisted data collection strategy, ARIANE.

Speaker: Michal Stekiel (Juelich Centre for Neutron Science)

20:00 Dinner

Tuesday, 5 December

Plenary: Talks by Michael Gradzielski (TU Berlin) and Piero Baglioni (University of Florence)

65 Ionic Assembly of Polyelectrolytes and Surfactants – Colloidal Complexes Rich in Structure and Properties

Ionic assembly of oppositely charged polyelectrolytes with each other or surfactants is a highly versatile way for constructing complexly structured colloidal systems in aqueous solution. Due to the richness of available polyelectrolytes and surfactants one can create here a multitude of structures dissolved in aqueous solution. Such complexes are interesting systems for selective solubilisation of active agents, but also a way to control the rheological properties by physical cross-linking, both properties of high importance for many applied colloidal formulations.
In this presentation we will look at various soluble interpolyelectrolyte complexes (IPECs) and polyelectrolyte surfactant complexes (PESCs) with a particular focus on how neutron scattering can contribute to understanding their structural features, which in turn allow to understand their properties. Here especially small-angle neutron scattering (SANS) and neutron spin-echo (NSE) spectroscopy have been employed, to be complemented by other characterisation techniques.
In summary, neutron scattering is a central tool to determine the structure and internal dynamics of IPECs and PESCs, which is central to gain a sound understanding of their properties. Such complexes are very versatile with respect to their structures and properties and therefore are interesting from a fundamental point of view, but also are relevant for a larger number of potential or actual applications in formulation science.

Speaker: Michael Gradzielski (Technische Universität Berlin)

66 Soft Matter for the conservation of Cultural Heritage

European Cultural Heritage (CH) is a crucial resource favoring social inclusion, job creation, and promoting resilience of our society against the emerging issues of the 21th century. Works of art interacting with the environment are prone to aging and decay. Soiling is a prime factor in the degradation of surfaces, chemical and mechanical degradation are often associated to soiling and lead to the disfigurement of a piece of art. We pioneered the synthesis and the application of several advanced systems for the consolidation and the cleaning of works of art, as microemulsions and chemical/physical gels. These systems constitute a new platform for Conservation of Cultural Heritage and are characterized by scale lengths below 100 nm, making neutrons and x-rays the primary tool for their investigation and the tailoring new cleaning tools. The new palette of materials for the conservation will be reviewed, focusing on the application of systems of increasing complexity, from o/w microemulsions to twin-PVA hydrogels. I will report on the application on artifacts of diverse origins, from Renaissance frescoes to Picasso and Pollock.Small-angle Neutron Scattering (SANS), recently used to detail the fractality and structure of a new class of green organogels, before and after swelling in two organic solvents commonly adopted in the cleaning of paintings, will be discussed. The swollen gels were then used for the conservation of Giorgio de Chirico and many other works of art.

Speaker: PIERO BAGLIONI (UNIVERSITY OF FLORENCE, DEPARTMENT OF CHEMISTRY &CSGI)

10:30 Coffee break

Plenary: Update on the status of FRM II by the MLZ Directors

Plenary: Update on the MORIS project

Plenary: Frank Schreiber for KFN

Plenary: Tommy Nylander for the MLZ User Committee

13:00 Lunch

Poster Session

67 P-018: 100 kN Testing Machine for In-Situ Neutron Scattering Experiments

A testing machine with a load capacity of 100 kN has been developed to conduct comprehensive mechanical assessments encompassing tensile, compression, and fatigue testing on industrially pertinent high-temperature alloys used in aerospace. The machine is developed for in-situ microstructural and mechanical characterization of high-temperature alloys subjected to concurrent mechanical and thermal stresses. The machine is designed to serve as a novel sample environment for conducting in-situ experiments at the FRM II, particularly at the instruments Stress-Spec, Spodi, SANS-1, and Antares. Neutron Diffraction is can be employed to ascertain parameters, including lattice constants, lattice misfit, phase fractions, and strain within the alloy, while Small-Angle Neutron Scattering allows to determine the size and volume fraction of nano-sized precipitates. Neutron imaging allows to observe crack formation. By mechanically loading the alloy at elevated temperatures, mimicking real-world application conditions, the microstructure can be directly investigated. The testing machine can be used to perform tests at temperatures of up to 1200°C. Furthermore, ongoing developments for the machine include the incorporation of a laser heating system and an active cooling device, enhancing its capabilities for future research.

Speaker: Massimo Fritton

68 P-016: A buffer-gas trap for the NEPOMUC positron beam: optimization studies with electrons

We outline the design and operation of a buffer-gas trap (BGT) for the NEPOMUC positron beam. BGTs use inelastic interactions with nitrogen molecules to efficiently capture positrons from a continuous source. They are invaluable for high-resolution studies of matter-antimatter interactions, antihydrogen research, and positronium laser spectroscopy. The device has been assembled at IPP Garching and successfully tested to produce bunches of up to $10^8$ particles using an electron beam with a similar intensity and energy spread to the remoderated NEPOMUC beam. The non-neutral plasma that accumulates in the trap can ejected in a 100 ns-long pulse at rates of between 0.01 to 10 Hz. The BGT is expected to extend the capabilities of the NEPOMUC by offering dense pulsed positron beams with narrow energy spreads (< 100 meV). The device is a vital component of the APEX (A Positron Electron eXperiment) project, which aims to produce a low-energy electron-positron pair plasma.

Speaker: Adam Deller (IPP)

ADeller_BGT_MLZ_2023.pdf

69 P-019: A physicochemical study on the role of LPS and CPS on the Lung Surfactant properties

The last pandemic highlighted the importance of understanding the interaction between external sources and eukaryotic membranes. Membrane models have been widely studied, but our knowledge of the interaction between them and external sources is far from fully understood. This gap limits the ability to achieve the next level of selectivity, efficiency, and targeting. Target of respiratory diseases is lung’s alveoli, composed of a complex of lipids and proteins known as lung surfactants. The lipid component that makes up this membrane is crucial in the interaction with external sources such as Gram(-) bacteria, which are responsible for many physiological and pathogenic processes and are involved in biofilm formation due to the presence of lipopolysaccharide (LPS), and capsular polysaccharide (CPS). We examined how the lipids affect the physicochemical properties of the system itself. Cholesterol lowers the lung surfactant layer transition temperature, making the membrane less rigid. Although only the precise lipid composition makes the lung surfactant stable at physiological temperature and able to withstand mechanical stresses. The adhesiveness of LPS to synthetic surfaces is essentially attributable to the structure of the polysaccharide and the charge distribution on the chain. While the affinity of CPS seems to be mediated by the presence of LPS. Also the affinity of CPS with natural membranes has been demonstrated this could be the precursor process of biofilm formation

Speaker: Noemi Gallucci (University of Naples Federico II)

70 P-008: A proposal: The next generation of sample environment magnets for the study of strongly correlated electron systems at MLZ

Strongly correlated electron systems (SCES) summarizes phenomena, which cannot be reconciled with the theory of the free electron gas. Instead, significant interactions between electrons are integral to understand these phenomena, mostly at very low temperatures when the impact of thermal fluctuations is low. On the atomic scale, properties like, e.g. spin orbit coupling, reduced magnetic dimensionality, low spin moments, spin dependent interaction of localized and itinerant electrons, quantum fluctuations or disorder form the ingredients of the zoo of SCES. This is why neutron scattering is indispensable for their study, as they probe the involved electronic states on the atomic scale.

Key to the investigation of SCES with neutrons is extending the available parameter space of the sample environment. Careful analysis of the status-quo at MLZ, the anticipated scientific challenges and needs, the recent technological revolution in magnet technology leads to the proposal of three new magnets:
- A 10T asymmetric horizontal magnet for small angle neutron scattering is focused on the use of polarized neutrons in forward scattering direction with both parallel and perpendicular access.
- A 11T wide access vertical field TOF magnet with a large horizontal opening for time-of-flight (TOF) neutron scattering, dedicated to the thermal TOF TOPAS and the upgraded TOFTOF.
- A 6T horizontal magnet optimized for triple axis spectroscopy with minimized dark angle coverage.

Speaker: Dr Lukas Beddrich (Research Neutron Source Heinz Maier-Leibnitz (FRM II))

71 P-009: A prototype for the backscatter detector system of PERC

The instrument PERC is currently under construction at the FRM II. Like its predecessors PERKEO II and PERKEO III, it will measure the beta spectra of neutron decay and determine several of its correlation coefficients. It aims to improve the precision by up to one order of magnitude over current best values. This enables testing the Standard Model and search for new physics via effective couplings.

PERC will observe neutron decay in an 8 m long neutron guide and a high magnetic field will guide the charged decay products to the main detector, positioned downstream of the experiment. In order to achieve the targeted precision, it is important to identify backscattering events, in which the electron only deposits a part of its energy in the detector, as this would otherwise alter the measured spectra. The magnetic field guides backscattered electrons upstream, where a detector system will identify the backscattering events by the coincidence time. The backscatter detectors will consist of two scintillation detectors and SiPM arrays on the backside for readout. Due to the high background in the area of the backscatter detector system, spatial resolution is necessary to avoid random coincidences.

Following a comparison of different possible setups via simulations with the Monte Carlo simulation tool Geant4, I determined the design most suitable for its purpose and built a prototype. We present first results of its characterization.

Speaker: Karina Bernert (TUM)

72 P-039: Adding functionality to cellulose thin films for photovoltaic applications

Cellulose nanofibrils (CNF) as a bio-based material are very attractive due to their resource-saving and renewable properties. They are biocompatible, flexible, lightweight, transparent, and show excellent mechanical strength. By adding functional properties, they can be used as base material for incorporating photovoltaic or electronic devices in a CNF-based composite material. We are aiming for building integrated photovoltaics. Solar cells with PEDOT:PSS as electron blocking layer, P3HT:PCBM as photoactive layer, and ZnO as hole blocking layer will be designed both in standard and inverted architecture directly deposited on a CNF composite. A CNF / Ag nanowires mixture can be used as electrode material to improve the conductivity of the Ag nanowire network as electrode. Spray deposition will be used as a suitable technique to fabricate such functional layers on a large scale with homogeneous surface and a low roughness. In-situ grazing incidence small- and wide-angle X-ray scattering (GISAXS/GIWAXS) will be used to observe the nanostructuring of each layer on the CNF composite material and to optimize the fabrication process.

Speaker: Xinyu Jiang (DESY)

73 P-087: ADVANCEMENTS IN SAMPLE ENVIRONMENT AT MLZ

Over the past several years, the Sample Environmental group at Julich Centre for Neutron Science (JCNS) at MLZ has made remarkable progress in updating and maintenance of the old cryogenic equipment and introducing the new ones. In addition to the tradition Orange-type wet cryostats, several cryogen-free closed cycle cryostats are in use. MLZ offers a wide range of dry and wet magnets with magnetic fields up to 12T and the temperature range 1.8-800K. To extend this temperature interval for 8T magnet an additional 3He-4He dilution insert was added. During preliminary tests of Kelvinox JT we reached 16mK in the absence of the neutron beam. An additional vacuum can allow using it also with the 12T magnet at PANDA instrument. In future we plan use this and similar Kelvinox JT inserts at other wet and dry cryostats, as well at the other magnets. The main advantage of such dilution insert is that due to the Joule-Thompson stage it is possible to run it directly from a 4K environment.
A new adiabatic demagnetization refrigerator (ADR) for PANDA can continuously operate in the temperature range from 0.3K to 300K. Moreover, in a single-shot mode cryostat can provide temperature as low as 100mK for a short period.
A new stop-flow setup for KWS instrument can provide fast mixing of two components with the high time resolution in a wide temperature and pressure ranges. MLZ also offers different high-pressure, low/high-temperature and specialized equipment.

Speaker: Valentyn Rubanskyi (Forschungszentrum Jülich GmbH)

74 P-073: Advancing the Fundamental Understanding of Novel Superalloys through Neutron and Synchrotron Radiation Studies

Superalloys are key materials of our modern society. They are not only used in harsh environments of power plants for energy conversion but also in aerospace or marine applications, as they combine excellent mechanical properties at high homologous temperatures with very good oxidation and corrosion resistance. To further improve the efficiency of engines, advanced superalloys with improved properties are needed that can operate at significantly higher temperatures or in even harsher environments of hydrogen-contaning fuels.
In this work, examples of Ni- and Co-based superalloys are presented whose development and characterization was supported by neutron and high energy X-ray diffraction and scattering methods. It will be shown, for example, how in-situ high energy X-ray diffraction measurements revealed the deformation behaviour and formation of unwanted intermetallics phases during high temperature deformation, how small angle neutron scattering results could be used to adjust the alloys’ heat treatments to optimize their mechanical properties and how neutron and X-ray diffraction helps to understand the effect of hydrogen on these superalloys.

Speaker: Steffen Neumeier (Friedrich-Alexander-Universität (FAU) Erlangen-Nürnberg)

75 P-080: Aging-related changes in the Lithium Distribution of 18650-type Li-ion batteries

Electrochemical cycling of lithium-ion batteries proceeds through an active exchange of lithium ions and electrons between the cathode and anode materials. Besides material properties, such exchange is facilitated by cell parameters like electrode dimensions and geometry, current density, temperature, pressure, reaction rate etc. Such parameters are neither uniformly distributed nor static in general and, therefore, serve as stabilizing factor of heterogeneous states in Li-ion batteries typically reflected in the lithium concentration distribution in the electrodes [1, 2].
In previous studies it was shown that with cell aging the distribution of the lithium-ions in the graphite anode of 18650-type lithium-ion batteries changes [3]. In this contribution, a set of cells at different state-of-health was measured with spatially resolved neutron powder diffraction. The results have shown changes of the lithium distribution over the lifetime of a commercial 18650-type lithium-ion battery.

1. Senyshyn, A., et al., Homogeneity of lithium distribution in cylinder-type Li-ion batteries. Scientific Reports, 2015. 5(1): p. 18380.
2. Petz, D., et al., Heterogeneity of Graphite Lithiation in State-of-the-Art Cylinder-Type Li-Ion Cells. Batteries & Supercaps, 2021. 4(2): p. 327-335.
3. Mühlbauer, M.J., et al., Inhomogeneous distribution of lithium and electrolyte in aged Li-ion cylindrical cells. Journal of Power Sources, 2020. 475: p. 228690.

Speaker: Dominik Petz

76 P-022: An indirect spectrometer of type Mushroom for the FRM II

Magnetic systems are a fertile ground for the design of novel quantum and topologically non-trivial states characterized by exotic excitations. Examples include spin chain and square-lattice low-dimensional antiferromagnets, quantum spin liquid candidates, spin-ice compounds, and unusual spin textures. Key features of the ground state and finite-temperature behavior of such magnetic systems are captured by the spectrum of their excitations. Their intrinsically complex dispersion relations occupy large volumes in the (Q, E) space and require long measurement times when measured on triple-axis spectrometers. Instead the use of a multiplexing secondary spectrometer allows for exploring the (Q, E) space more efficiently.

We therefore propose an indirect-geometry spectrometer with a time-of-flight primary chopper spectrometer including an advanced nested-mirror neutron optics providing a well-defined and very bright beam spot at the chopper position giving flexible means to adjust the primary resolution. The secondary spectrometer consists of a large spherical crystal analyzer covering the upper part of the instrument and a flat detector area below the sample position. It realizes a large acceptance of the analyzer crystal array making use of crystals with a wide mosaic spread and recovering a good energy resolution via the so called prismatic focusing. The accessible wavelength band is foreseen to be 1 – 10 Å with an adjustable wavelength resolution of 1%- 5%.

Speaker: Mr Ran Tang (Technische Universität München)

77 P-028: Automated sample change systems for thermal powder diffractometers

At large-scale facilities, a growing demand for automated measurements in combination with mail-in services for samples has long since been observed. Automatized systems significantly improve the efficiency in the usage of measurement slots, and simultaneously also widen the scope of scientific applications. In particular, they enable to measure large series of samples prepared by different processing routes or varying the chemical composition. Small series of such measurements at room temperature have already been carried out at SPODI using a semi-automated 10-sample carousel, which is also the basis for the very successful rapid access program.

However, there is an increasing demand to extend rapid access measurements to non-ambient temperatures, in particular for measurements that only require one temperature point above and one below a certain phase transition temperature. These would benefit greatly from a fully automatized non-ambient sample changer.

Within the MORIS upgrade program, we plan employ a common pool of automatized sample environment for the three thermal powder diffractometers at SR8 at the FRM2, which is presented in this contribution. We plan to use a multi axis robotic arm as flexible sample changer for all temperatures at each instrument. The basic concept is the combination of a robot equipped by a sample magazine with dedicated sample environment. These must be suitable for automatic sample change at elevated and cryogenic temperatures.

Speaker: Christoph Hauf

78 P-048: Automated sample loading using Panda cobot from Franka Emika

Robots and cobots (collaborative robots) were designed to change manufacturing and production processes at factories. Typical application of an industrial robot would be to replace a human on repetitive tasks, which involve endurance, speed, and precision. Industrial robots usually operate in environments isolated from human contact. Instead, cobots are designed to provide human robot interaction within a shared space: they are build out of lightweight materials with rounded edges, demonstrate human-like speed and force, and are equipped with torque sensors to handle collisions.

Neutron hall is an environment with extra safety protocols due to its radiation sources. One of the strategies to mitigate the risk of radiation exposure would be to reduce presence of workers in the hall to minimal times if not to avoid completely. For that certain operations could be automated and executed in a given time by a robot.

In this work we demonstrate an automated system for sample loading to one of the instruments, located in the neutron hall of Heinz Maier-Leibnitz Zentrum. This system is built using Panda cobot from Franka Emika Gmbh. The control software is written in C++ [1] and is integrated into TANGO network at MLZ.

[1] https://forge.frm2.tum.de/review/plugins/gitiles/jcns/tango/franka/+/refs/heads/master

Speaker: Konstantin Kholostov (Forschungszentrum Jülich GmbH)

79 P-026: Biopolymer-Templated Deposition of Hierarchical 3D-Structured Graphene Oxide/Gold Nanoparticle Hybrids for Surface-Enhanced Raman Scattering

Cellulose, a well-known natural biopolymer, possesses numerous advantages such as cost-effectiveness, renewability, ease of processing, and biodegradability [1]. Due to these inherent merits, cellulose has emerged as a promising bio-based substrate capable of synergistically combining with conductive materials (e.g., metals or carbon-based materials) for diverse applications including sensors, smart windows, and bioelectronics [2]. Typically, Surface Enhanced Raman Scattering (SERS), an advantageous analytical technique, allows for the rapid detection and structural analysis of biological/chemical compounds through their spectral patterns in nanotechnology [3]. Crucial for SERS is fabricating the substrates with strong enhancements of the Raman signal over large areas and with a low fabrication cost. Herein, we present a straightforward approach utilizing the layer-by-layer (LBL) spray coating method to fabricate cellulose nanofibrils (CNF) films loaded with gold nanoparticles and Graphene Oxide to serve as SERS substrates. To gain comprehensive insights into the nanostructuring evolution, advanced X-ray scattering techniques, grazing incidence small-angle X-ray scattering was employed to investigate the fundamental mechanisms. Thereby, our approach provides a reference for facile and scalable production of universally adaptable SERS substrates. This research opens up new avenues for achieving high-performance electronic materials in a more sustainable manner.

Speaker: Yingjian Guo (Deutsches Elektronen-Synchrotron DESY)

80 P-096: BornAgain - open-source cross-platform software to simulate & fit GISAS & reflectometry

BornAgain [1,2] is an open-source software package to model and fit SAS, GISAS, off-specular scattering, and reflectometry. It was designed to fully reproduce the functionality of the standard software IsGisaxs [3], allow for hierarchical sample models of arbitrary complexity, and support neutron polarization and magnetic scattering. It can be used either through a graphical user interface or through Python scripting. After a change of the developer team, and several releases that focused on consolidating the code base, we are now ready to implement new functionality.

[1] https://bornagainproject.org
[2] G. Pospelov et al, J. Appl. Cryst. 53, 262–276 (2020)
[3] R. Lazzari, J. Appl. Cryst. 35, 406 (2002)

Speaker: Mikhail Svechnikov (FZ Jülich)

81 P-084: Broadening the dynamic range of PGAA using a high-efficiency detector array

We studied how we can improve the analytical sensitivity of prompt gamma activation analysis using the most advanced gamma-spectrometry system, FIPPS/IFIN at ILL. The high counting efficiency and the coincidence possibility with altogether 64 HPGe detectors offer a unique opportunity to unfold the spectra where a strong matrix masks the weak signal from trace components, like Cl a highly important corrosive in Fe or silicate matrices. The detection limits and the dynamic range for such measurements were determined at FRM II, Garching in high-flux cold neutron beam with a single Compton-suppressed HPGe detector and were found to be about 80 ppm for the iron matrix. Small-mass model samples were used at ILL with known amount of trace Cl on the 1-100 ppm level using Fe plates together with PVC films. Using the FIPP/IFIN detector system, we could achieve an improvement of an order of magnitude in the detection limit.

Speaker: Dr Zsolt Revay (PGAA)

82 P-114: Closed-loop approach for automated instrument tuning and alignment

In the rapidly evolving landscape of experimental research, the integration of advanced technologies has conducted in a new era of precision and efficiency. Robotic systems, supported by artificial intelligence, have become important tools for conducting experiments with high levels of control and accuracy. Among these rapid developments, the closed-loop approach stands out as a paradigm shift in the field of automated instrument tuning. In this poster, I am going to show you how closed-loop machine learning suite based on Bayesian optimization can help with not only performing the experiments but also instrument calibration. I will demonstrate this approach on several examples, like alignment of triple axis spectrometer, tuning of computer vision camera system, Laue pattern spot finding or optimization of sample grabbing and tuning.

Underlying software package based on the integration between NICOS [1] and NIMS-OS [2] will be presented, simplifying use of closed-loop machine learning, and providing the method to broader audience of scientists.

[1] Brandl, Georg, et al., 10th International Workshop on Personal Computers and Particle Accelerator Controls. No. IMPULSE-2014-00016. FZJ, 2014.
[2] Tamura, Ryo, Koji Tsuda, and Shoichi Matsuda. arXiv preprint arXiv:2304.13927 (2023).

Speaker: Petr Čermák (MGML, Charles University)

83 P-077: Comparative Analysis of Reactivity of Al and Ga Doped Garnet Solid State Electrolyte at the Interface with Li Metal

The lithium garnet Li7La3Zr2O12 (LLZO) is a leading solid state electrolyte candidate for an All-solid-state battery (ASSB) containing Li as anode because of its high ionic conductivity, high toughness and wide electrochemical stability. Undoped LLZO exists in two polymorphic phases; a low conductivity tetragonal phase and a high conductivity cubic phase. Dopants in LLZO play a critical role in determining Li/LLZO interface stability and influencing the overall performance of an ASSB. In this work, we explore the differences between Al- and Ga-doped LLZO when interfaced with Li metal, using a combination of several techniques. We show that formation of Li metal interface with Ga-doped LLZO leads to a propensity of Ga to move from LLZO and form Ga-Li alloy layers, resulting in loss of dopant and associated changes in structure and electrochemical behavior not present in Al-doped LLZO. X-ray photoelectron spectroscopy with in situ lithium deposition shows the formation of a Ga-Li alloy at the interface, while Al is shown to be stable to reduction by lithium metal. Through neutron diffraction we observe that doping of LLZO with Ga results in complete transformation of the cubic phase to tetragonal phase when in contact with lithium metal, and although some performance characteristics may be enhanced through Ga doping, the materials stability is compromised significantly compared to Al doping.

Speaker: Dr Neelima Paul (Technical University of Munich, Heinz Maier-Leibnitz Zentrum (MLZ))

84 P-010: Comparison of dcMS and HiPIMS Gold Deposition on Polystyrene, Poly-4-vinylpyridine and Polystyrenesulfonicacid

Gold deposition via high power impuls magnetron sputtering (HiPIMS) allows to coat thin metal layers on heat sensitive materials like polymers allowing increased adhesion compared to an evaporated gold layer. In addition, this particular technique allows deposition at a lower deposited thermal energy in comparison to conventional magnetron sputtering. However, the low temperature nucleation and growth processes of HiPIMS are not sufficiently known. Therefore, we investigate the morphology and structure of thin gold layers on three polymers, namely Polystyrene (PS), Poly-4-vinylpyridine (P4VP) and Polystyrenesulfonicacid (PSS). The polymers are spincoated on silicon to obtain polymer thin films as substrates. These polymers are of interest as they show different functional moieties and thus are expected to influence the growth of the gold layer. We present results of our investigations using atomic force microscopy (AFM), scanning electron microscopy (SEM), grazing incidence small angle X-ray scattering (GISAXS) and grazing incidence wide angle X-ray scattering (GIWAXS).

Speaker: Yusuf Bulut

85 P-115: Computer vision integration into the NICOS

Our work focuses on the development of an Automatic Laue Sample Aligner (ALSA) that allows to increase
the sample size for neutron experiments, by fully automating the co-alignment process [1].
However, the sample manipulation, which utilizes a precise robotic arm (Mecademic Meca500 [2]),
requires also advanced use of computer vision (CV). This poster presents our integration of general computer vision
capabilities into the instrument control software NICOS [3].

The whole set of code includes integration of the Basler cameras hardware, image processing techniques (object detection),
state-of-art cameras alignment procedures and ways to store and stream obtained images.
We've achieved substantial gains in automation efficiency. Looking forward, we envision native
CV support with NICOS, to cover a wider spectrum of laboratory tasks beyond crystal detection,
from instrument calibration to dynamic decision-making.

We invite meeting attendees to explore our achievements and join the conversation about the practical applications and potential growth
of CV in NICOS.

[1] https://mambaproject.cz/alsa
[2] "Six-axis robotic arm driver: Zoning out with Frappy and NICOS", poster, Štěpán Venclík, MLZ users 2023
[3] Brandl, Georg, et al., 10th International Workshop on Personal Computers and Particle Accelerator Controls. No. IMPULSE-2014-00016. FZJ, 2014.

Speaker: Tomáš Červeň (Charles University)

86 P-067: Concept of an *active learning-assisted* measurement using multiplexing setup at a three-axes spectrometer

Three-axes spectrometers (TAS) are considered one of the most flexible and versatile instruments for inelastic neutron scattering measuring fundamental excitations (phonons, magnons, and crystalline electric field) in materials with sub-meV energy resolution. However, the limitation of a three-axes spectrometer usually comes from the restriction of a point-by-point measurement strategy in the reciprocal space which does not allow investigations in short time scales. To increase the data collection efficiency in terms of (Q,ω)-coverage of a conventional TAS instrument, multiplexing techniques have been developed (such as CAMEA at PSI, UFO-IN12 at ILL, BAMBUS-PANDA and Multiplexing-PUMA at MLZ). In these techniques for an incoming neutron energy E$_i$ in the primary side of the spectrometer, several (Q, E$_f$)-channels are employed to cover a larger range of (Q,ω) in the secondary side of the spectrometer. In parallel, there is also a growing interest in optimizing and enhancing the measurement strategy at a conventional TAS by employing artificial intelligence. Here we will be presenting a concept to generalize an active learning-assisted TAS measurement [1] for multiplexing setups and show its potential for improving the experimental strategy for users.

Reference: [1] M. T. Parente, G. Brandl, C. Franz, U. Stuhr, M. Ganeva, and A. Schneidewind. Active learning-assisted neutron spectroscopy with log-Gaussian processes. Nat. Comm. 14, 2246 (2023).

Speaker: Dr Avishek Maity (Jülich Centre for Neutron Science (JCNS) at Heinz Maier-Leibnitz Zentrum (MLZ), Forschungszentrum Jülich GmbH, Lichtenbergstraße 1, 85747 Garching, GERMANY)

87 P-113: Core-shell Nanoparticles for Wet-coated Surface-enhanced Raman Scattering (SERS) Application

Plasmonic nanoparticles (NPs) or score-shell NPs are extensively used in various applications, in particular, Surface-enhanced Raman Spectroscopy (SERS), which has been widely used in viral molecular detection. Virus Raman detection research is mainly focused on the detection of viral nucleic acid and various bases that make up the nucleic acid, but the detection of viral proteins is rare. In addition, there is limited knowledge about the interaction between virus proteins and the core-shell NPs with different shapes. Therefore, obtaining more detailed information on the relationship between the behaviour of viruses at the surface of core-shell NPs and the enhanced Raman intensity can lead to the development of advanced NPs for the detection of viruses. Here, taken into the consideration of sustainable and scalable demand for industry, spraying water-based cellulose nanofiber (CNF) and core-shell NPs solutions is preferred for the fabricating of sensors. The in-situ small-angle grazing incidence X-ray scattering (GISAXS) technique is used to investigate the self-assembly of CNF and NPs with various shapes in real-time during deposition. After the fabrication of sensors, some measurements will be taken, such as Raman, AFM, TEM and XPS et al. Furthermore, the relationship between the shape of NPs, sensor performance, and virus behaviour is explored and constructed to lay solid foundations for the fabrication of sensors for virus detection.

Speaker: Jungui Zhou (DESY)

88 P-001: Correlating thermoelectric performance with nanostructure of conductive polymer blended with lignin

Developing efficient, sustainable thermoelectric (TE) devices to harness waste heat is challenging due to the reliance on rare elements in conventional materials. Recently, conducting polymers, particularly Poly(3,4-methylenedioxy thiophene): poly(styrene sulfonate) (PEDOT: PSS) blends, have shown promising TE performance improvements [1]. However, PEDOT has limitations, such as sensitivity to humidity and electrical and microstructural irregularities. Blending lignin with conducting polymers can address these issues [2,3]. Lignin, a readily available plant resource, is a potential bio-based dopant and hole transport material. Nevertheless, the thermoelectric properties of PEDOT blended with lignin remain unexplored. We have optimized an aqueous PEDOT: lignosulphonate (LS) solution and deposited thin films through spin coating. Our study includes UV-Vis spectroscopy and grazing-incidence wide-angle X-ray scattering to analyze structural changes and doping effects on thermoelectric properties. Additionally, we will report on electrical resistivity and TE measurements. These investigations aim to determine if sustainable lignosulphonate can replace costly PSS as a dopant and dispersant for eco-friendly energy generation.
References
[1] Serrano-Claumarchirant, José F., et al., ACS Applied Energy Materials, 2019, 3.1, 861.
[2] Ajjan, F. N., et al., Journal of Materials Chemistry A, 2016, 4.5, 1838.
[3] Culebras, Mario, et al., Advanced Sustainable Systems, 2020, 4.11, 2000147.

Speaker: ANURADHA ANURADHA (Deutsches Elektronen-Synchrotron, DESY)

89 P-089: CREScent: High-Precision Electron Spectroscopy using Cyclotron Radiation Emissions

High-precision measurements of angular correlations in neutron beta decay address a number of questions which are at the forefront of particle physics. For a new generation of beta decay experiments, like the PERC (Proton Electron Decay Channel) experiment currently under construction in Munich, frequency-based beta spectroscopy methods using the cyclotron radiation emitted by electrons in a homogeneous magnetic field have been emerging as new approaches for high-precision beta spectroscopy. The CREScent experiment is a proof-ofprinciple experiment aiming to combine the CRES (Cyclotron Radiation Emission Spectroscopy)-technique with the signal amplification qualities of a RF cavity, naturally compensating for the extremely weak signal power of the expected cyclotron radiation pulses.

Speaker: Alberto José Saavedra García (Atominstitut - TU Wien)

90 P-102: Crystal Structure of Ethylene Carbonate

Performance and safety/stability of Li-ion batteries can be improved by either optimizing the charge storing electrodes or the charge transfer mediating liquid electrolytes. Most of the research since the commercialization of Li-ion batteries by Sony in 1991 has been focused on the electrodes and less on the electrolytes. An important class of solvents used in electrolytes are linear and cyclic carbonates, because of their good physicochemical and electrochemical properties when mixing two or more of them together with lithium salt. Thereby, ethylene carbonate (EC) is a vital part of the electrolyte with its ability to form the solid electrolyte interface, avoiding exfoliation of the graphite anode.[1] After the determination of the crystal structure of EC from single crystals[2,3] this contribution presents room temperature data obtained by Neutron Powder Diffraction at SPODI (FRM II), Total Scattering and temperature dependent Powder X-Ray Diffraction data obtained at beamline P02.1 (DESY).
[1] B. Flamme et al., Guidelines to design organic electrolytes for lithium-ion batteries: environmental impact, physicochemical and electrochemical properties, Green Chem. 19, 1828-1849 (2017).
[2] C.J. Brown, The Crystal Structure of Ethylene Carbonate, Acta Cryst. 7, 92-96, (1954).
[3] P. M. Matias et al., Single Crystal Neutron Diffraction Analysis (15K) and ab initio Molecular Orbital Calculations for Ethylene Carbonate, Journal of Molecular Structure (Theochem) 184, 247-260 (1989).

Speaker: Lea Westphal (FRM II)

91 P-012: Design, construction, and commissioning of a levitated dipole trap for electron-positron pair plasma studies

Magnetic dipole traps have demonstrated good confinement properties for both non-neutral and quasi-neutral plasmas, making this a highly suitable type of trap for the creation and study of low-temperature, long-lived electron-positron pair plasmas. To generate such a plasma, the APEX (A Positron-Electron eXperiment) Collaboration is planning to inject positrons (supplied by the reactor-based beam NEPOMUC, then collected into pulses in a buffer-gas trap) into a dipole magnetic field, which is previously loaded with a comparable population of electrons.

The "floating coil" (F coil) is a 15-cm-diameter high-temperature superconducting (HTS) closed coil, which when charged and levitated forms our dipole trap. A second HTS "charging coil" (C coil, I = 151 kAt), which is integrated into the walls of this sub-chamber, inductively charges the F coil to a strength of Baxis = 0.5 T.

By utilizing a feedback-stabilised levitation technique, magnetic field lines from the charged F coil do not intersect material surfaces (e.g. mechanical supports). The current levitation record is 3.5 hrs. The future addition of an actively cooled thermal radiation shield surrounding the trapping region will slow the resistive decay due to thermal warming, therefore increasing levitation time.

Finally, presented is results from first experiments (i.e. magnetic field line visualizations and e- injection) and next steps for making e- plasmas and later injecting cold, dense pulses of e+.

Speaker: Alexander Card (Max-Planck-Institut für Plasmaphysik)

92 P-107: Design, fabrication and nano-scale characterization of novel SEI layers

Lithium has a high specific capacity of 3860 mAh g−1 and a low electrochemical potential (-3.04 V), promising a high energy density lithium metal battery (LMB). However, the growth of lithium dendrites during charging and discharging would penetrate the separators in LMBs, which leads to short circuit. To inhibit the growth of lithium dendrites, we focus on optimizing the SEI layer through synergetic additives (FEC & LiNO3) in commercial carbonate electrolytes.
In the traditional carbonate electrolytes consisting of ethylene carbonate, dimethyl carbonate, lithium hexafluorophosphate, lithium bis (fluorosulfonyl)imide, the types and contents of the additives (FEC & LiNO3) are precisely regulated. We probe the electrochemical performance and morphology via Galvanostatic tests and scanning electron microscopy. Compared the control sample, Li-Li symmetrical cells, Li-Cu cells and Li-Ni83(LiNi0.83Co0.05Mn0.12O2) with the synergetic additives display better electrochemical performance with smoother surface of lithium metal.

Speaker: Zhuijun Xu (Technische Universität München)

93 P-038: Devices for Correcting Phase Aberration for Longitudinal MIEZE at RESEDA

The RESEDA instrument, situated at the FRM II facility, operates as a resonant spin-echo spectrometer utilizing the MIEZE (Modulated Intensity with Zero Effort) technique in a longitudinal geometry. While RESEDA offers access to a broad range of energy scales, its optimal resolution for momentum-transfer vectors is primarily concentrated at small scattering angles. Recent advancements have demonstrated the extension of the accessible scattering angle range through the incorporation of Magnetic Wollaston Prisms (MWPs) [1]. However, MWPs are not suited for longitudinal MIEZE. Consequently, there is a pressing need to develop a similar device capable of providing spatial-intensity modulation capabilities within the L-MIEZE geometry. In this contribution, we explore various magnetic coil configurations designed to generate the required field gradient and present the results of numerical simulations.

[1] F. Li, J. Appl. Cryst. (2022). 55, 90-97

Speaker: Luke Jatho (FRM2 - RESEDA)

94 P-051: Diffraction computed tomography with X-rays and neutrons

Diffraction and imaging using X-rays and neutrons are widely utilized in different fields of engineering, biology, chemistry, and/or materials science. The additional information gained from the diffraction signal by X-ray diffraction and computed tomography (XRD-CT) can give this method a distinct advantage in materials science applications compared to classical tomography. Its active development over the last decade revealed structural details in a non-destructive way with unprecedented sensitivity. The current contribution reports an attempt to adopt the well-established XRD-CT technique for neutron diffraction computed tomography (ND-CT). The feasibility of ND-CT is demonstrated, and it is also shown that the ND-CT technique can provide a non-destructive view into the interior of a specially designed "phantom" sample, as well as the commercial Li-ion batteries, delivering structural information consistent with the reference XRD-CT experiments.

Speaker: Vladislav Kochetov (TUM)

95 P-011: EFFECT OF PEROVSKITE NANOCRYSTAL NUCLEATION SEEDS ON MICROSTRUCTURE AND CRYSTALLIZATION PATHWAYS IN ORGANIC-INORGANIC HALIDE PEROVSKITE THIN FILMS

Organic-inorganic halide perovskites have gained a huge interest in the scientific community owing to their favorable optoelectronic properties combined with their ease of production and abundance of raw materials. [1] In many cases, polycrystalline thin films are used for which thin film crystallinity and morphology are key factors affecting the perovskite’s properties. Various methods have been utilized to improving the mentioned factors [1] from which we present a fairly novel approach employing external perovskite nanocrystals as seeds for printed thin films and present their influence on crystallization kinetics and microstructure based on in-situ grazing incidence wide angle X-ray scattering (GIWAXS) measurements conducted at beamline P03, PETRA III synchrotron DESY, Hamburg [2].

[1] C. Lin et al, Adv. Funct. Mater. 29., 1902582 (2019).
[2] A. Buffet et al, Journal of Synchrotron radiation, 19.4, 647-653 (2012)

Speaker: Mr Altantulga Buyan-Arivjikh (Technical University of Munich, TUM School of Natural Sciences, Department of Physics, Chair for Functional Materials)

96 P-002: Effect of pressure on the micellar structure of PMMA-b-PNIPAM in a water/methanol mixture

In aqueous solution, amphiphilic block copolymers consisting of a short permanently hydrophobic poly(methyl methacrylate) (PMMA) and a long thermoresponsive poly(N-isopropyl acrylamide) (PNIPAM) block self-assemble into spherical core-shell micelles. At atmospheric pressure, the micellar shell of PMMA-b-PNIPAM strongly dehydrates and shrinks above the cloud point Tcp of PNIPAM. However, when pressure is applied, the dehydration of the PNIPAM shell is less strong. Besides temperature and pressure, the addition of a water-miscible co-solvent affects the self-assembly behavior of PMMA-b-PNIPAM. At 0.1 MPa, adding a small amount of methanol (10 % v/v) leads to softening of the PMMA core and a slight shrinkage of the PNIPAM shell [1]. Here, we present the phase behavior and the pressure- and temperature-dependence of the micellar structure of PMMA21-b-PNIPAM283 in a 90:10 v/v D2O/CD3OD mixture in a pressure range between 10 and 250 MPa. Turbidimetry shows that adding methanol to PMMA-b-PNIPAM in D2O shifts the maximum of the coexistence line to a higher pressure and temperature. Synchrotron small-angle X-ray scattering reveals that the size of the micellar core decreases with increasing pressure, which is particularly pronounced for pressures of 200 MPa and above. At all pressures studied, the micellar shell shrinks only slightly when heating across Tcp.
[1] C.-H. Ko, C. M. Papadakis et al., Macromolecules 54, 5825-5837 (2021).

Speaker: Pablo Alvarez Herrera (Technical University of Munich)

97 P-020: Effect of steady state shear on colloidal gelation

Gels represent an industrially important state of matter. Here we study the effect of a simple shear on a colloidal scale gelation process with ultra small and small angle neutron scattering. The structural understanding of the effects of steady state shear on colloidal gelation has largely been inferred from oscillatory rheological studies, an essentially perturbative approach, and complementary computer simulation. In this study we examine directly the structural evolution of a gelling system in situ in a simple shear field (Couette flow) using neutron scattering over an extended range of scattering vectors. This range of scattering vectors contains information about the individual nano-scale sol particles and the network formed by the gelling particles. Gelation was initiated from a model system of silica nanoparticles where a slight adjustment of the pH modulated interparticle interactions. In the absence of shear we observe that the sol rapidly increases in viscosity until flow is arrested, in the case of an applied shear we observe that viscosity rapidly increases until it reaches a maximum, and then viscosity decreases. Scattering curves at constant shear rate were modelled to yield the growth and volume fraction of clusters. Derived structural parameters were used to calculate viscosities from a simple theoretical model5 to give excellent agreement with measured viscosities.

Speaker: Christopher Garvey (MLZ)

98 P-059: Effect of the precursor conformation on the structure of polypeptide single chain nanoparticles (SCNPs)

Single chain nanoparticles are soft nano-objects made from individual polymer chains crosslinked intramolecularly. Due to the internal random crosslinking between functional groups of the same chain, a sparse conformation is usually achieved which displays many common structural features with intrinsically disordered proteins (IDPs). Lately, there has been great interest in expanding SCNPs to biodegradable and biocompatible polymers, such as proteins.
We synthesized two types of SCNPs: poly- L- lysine- and bovine serum albumin (BSA) using disuccinimide ester linkers that mainly react with lysine moieties. To understand the role of the chain conformation of the precursor on the resulting SCNP morphology, we have systematically varied the solvent conditions: pH, salt and for the case of BSA-SCNPs, the denaturant concentrations, as well as the cross-linker concentration. By studying the resulting SCNPs with dynamic and static light scattering as well as small angle neutron scattering, we found that indeed the precursor conformation has a strong effect on the SCNP morphology. For BSA-SCNPs, more extended precursor conformations are able to collapse more by intramolecular cross-linking. Also, the longer cross-linker is more effective in chain compaction due to its ability to form larger intramolecular loops. Similarly, for the cationic PLL, pH and salt variation affect the chain conformation. However, the crosslinking results in aggregation due to the stiffness of the precursor.

Speaker: Thu Phuong Le (Materials Physics Center)

99 P-037: Electric Field-Induced Assembly in Highly Crosslinked Ionic Microgels

Poly(N-isopropylacrylamide) based microgels are interesting colloidal systems to probe cooperative phenomena such as structural ordering, crystal nucleation, glass formation, etc. They can be packed to effective volume fractions(eff) beyond the hard-sphere close-packing (cp) and their average interparticle distance, as can be smaller than the particle diameter, d[1]. Here, we report the electric field-induced assembly of highly crosslinked poly(N-isopropylacrylamide-co-Acrylic acid) (PNIPAM-co-AAc) microgels studied using confocal laser scanning microscope (CLSM) and small-angle neutron scattering (SANS). At low eff =0.04,0.17, in the presence of an electric field, the microgels form strings, tubes and islands of body-centered cubic (bct) structures. Though ellipsoidal particles under the influence of an electric field formed tubes [2], no analogous tubular assembly has been reported thus far for hard or soft isotropic particles. Beyond the maximum close packing (eff =0.79,1.07 > cp), solid-solid (s-s) phase transition from a hexagonal lattice to a square lattice is observed, suggesting a diffusive nucleation and growth process. We discuss the experimental phase diagram and compare our observations to the theoretical phase diagram for soft dipolar spheres [3].
References
1. J. Brijitta, P. Schurtenberger, Curr Opin Colloid Interface Sci, 2019, 40, 87–103.
2. JJ. Crassous, et al., Nat Commun, 2014, 5, 1–7.
3. A.-P. Hynninen, M. Dijkstra, Phys Rev Lett, 2005, 94, 138303.

Speaker: BRIJITTA JOSEPH BONIFACE (MLZ, FRM II)

100 P-070: Electrodeposited Lithiophilic Nanoparticles As Artificial Interphase for Anode-Free Lithium Ion Batteries

The world is impatiently waiting for the lithium metal - to finally make a step forward from current battery technology. Safer and higher in energy and power density are the targeted improvements, and while the latter is met by the choice of lithium metal as anode (or more radically, no anode at all), the safety aspect is not as easily reached. The anode interphase was identified long ago as the critical element to this endeavour. Initial attempts at understanding and developing the solid electrolyte interphase (SEI) formation and its mechanisms on graphite have been paralleled by using alternative electrolytes (polymer, ceramic) or additives as well as numerous kinds of protective coatings to improve performance, lifetime and safety of battery cells. Lithiophilic metal coatings could also do the job, and it has been shown that sputtered Au or Zn layers on Li metal could prevent dendritic growth in a cell. The concept of artificial SEI engineering can be expanded on by using lithiophilic nanoparticles as opposed to continuous coatings. Nanoparticle decorated current collectors or lithium metal anodes can be made by electrodeposition, where the experimental conditions allow for the tuning of particle number density, size and composition. A precise understanding of the intermetallic phases formed between lithium and a lithiophilic-metal nanoparticle should enable their optimised design for highest performance and durability.

Speaker: Gilles Moehl (ADVMAT)

101 P-013: Enhanced air stability of Tin‑Based Perovskite Solar Cells with Quercetin

As the most essential alternative materials for eco-friendly perovskite solar cells (PSCs), tin-based perovskites have achieved an efficiency of 14.81 %, which is far less than 25.7 % of lead-based champion devices. The main reason is that it is easy to oxidize Sn2+ to Sn4+ in the presence of oxygen and water due to the low stability of the Sn2+ state. The oxidation of Sn2+ will form the Sn (Ⅳ) vacancies in the perovskite structure, leading to p-type self-doping and introducing additional defect states. These defects can enhance the device's leakage current and carrier recombination, limit the increase of open circuit voltage, and thus reduce the solar cell efficiency. Here, we plan to introduce quercetin, a phenolic derivative with antioxidation properties extracted from plants, as the additive to reduce the existence of Sn4+ and prevent the FASnI3 film from degradation. We use grazing-incidence wide-angle X-ray scattering (GIWAXS) to gain insights into the detailed steps of growth and degradation progress of the active layer. Thereby, GIWAXS offers a way to gain information about the time evolution during the crucial steps of interface formation. The ultimate goal of our work is to design efficient and stable tin-based PSCs to develop a systematic and reproducible strategy for air stability and high-efficiency PSCs.

Speaker: Xiaojing Ci

102 P-057: Enhanced air stability with solid additive EH-P in PBDB-TF-T1:BTP-4F-12 organic solar cells

The performance of organic solar cells (OSC) has got great development due to material design and device engineer, while the poor stability of PSC and toxic solvents during device fabrication are the most two big issues nowadays. Here, we select a green-solvent based material system PBDB-TF-T1:BTP-4F-12, and explore a solid green fluorescent polymer additive EH-P, realizing the full fabrication without any aromatic or halogenated solvents. The EH-P doping solar cells exhibited comparable performance as DPE does. Furthermore, the in-situ GIWAXS measurement was carried out with the cell under light, where EH-P doped cells shown much better stability compared with the reference ones. The degradation process of the reference T1:Y12 cells was observed and the evolution of GIWAXS patterns could be divided into three stages, where the q and coherent length of π-π stacking would change both. The doping of EH-P could suppress the evolution at the first stage and stable the films crystallinity. GISAXS results before and after aging illustrate that EH-P could suppress the swelling of phases during the light degradation process. Improved phase separation with EH-P doping and enhanced stability after aging were found from AFM images. In a word, EH-P could improve the stability of PBDB-TF-T1: BTP-4F-12 solar cells without too much effect on performance, which shows great potential as a solid additive in organic solar cells.

Speaker: ZERUI LI (TUM)

103 P-041: Enhanced stability with Ni2+ addition-based perovskite solar cells by slot-die-coating

Perovskite solar cells (PSCs) is a promising technique in energy harvesting. Many reports have been focused on PSCs mainly on the enhancement of the power conversion efficiency (PCE) and stability due to the sensitivity to hydrogen, oxygen and light. So far, the lab-scale PSCs develop rapidly with high PCE and decent stability after many researchers engaging in an effort to optimize the properties of PSCs through composition engineering, additive engineering and interface engineering. However, the lack of stability would be a key issue when it comes to the commercialization of PSCs. Thus, how to improve the stability of large-scale PSCs is critical for the practical application. As reported before, the introduction of bifunctional metal Ni2+ enhanced grain size and defect passivation through using a method of controllable two-step sequential deposition perovskite films. Also enhanced PCE could be achieved for the Ni2+ addition-based PSCs with enhanced cell stability under ambient conditions. In this work, Ni2+ will be introduced to the slot-die-coating fabricated PSCs. The mechanism of Ni2+ improving PCE and stability of slot-die-coated PSCs will be demonstrated.

Speaker: Zhaonan Jin

104 P-056: Enhancement of a chemical hydrogen storage system by a catalyst

Hydrogen is one of innovative fuels which storage is a challenge so far. One of options is hydrogen storage in complex-hydride systems, where it is chemically bonded unless a sufficient heating is applied. Main virtues of a hydrogen storage system are: storage capacity, safety of use, reversibility, fast reaction rate and a moderate operation temperature. Amide-hydride mixtures, where NH3-emission into the environment is prevented by hydrides, are considered attractive hydrogen storage systems. Their another advantage is weight hydrogen storage density if alkaline or alkaline earth metals are used. 6Mg(NH2)2:9LiH (“69”) requires 500K to emit 5.2 wt.% H2 and about an hour to get fully dehydrogenated. However, when LiBH4 is admixed (“69x”, where x is LiBH4 quantity), the re/desorption rates are reported to enhance by a factor of 3. This is explained by formation of a Li-ion and proton conductive substance at operation temperatures: LiNH2–LiBH4, where LiNH2 is the first product of the reaction between Mg(NH2)2 and LiH. Dehydrogenation rates increase along with the amount of LiBH4. That leads to the hypothesis that different mixed phases appear in the course of operation depending on the amount of LiBH4. The behaviour of different LiNH2–LiBH4 ratios under heating has been examined resulting in a phase diagram of this system. A juxtaposition of various 69x systems with systems LiNH2–LiBH4 is planned after revealing their micro-structures by means of total scattering measurements.

Speaker: Anastasiia Kuznetsova (HZG)

105 P-058: Exploring Hydration Mechanisms in Poly(N-isobutyramide) and its Isomer, Poly(N-isopropylacrylamide).

Stimuli-responsive polymers hold a prominent position in the field of functional materials due to their remarkable adaptability to changing environmental conditions. Among these, thermo-responsive polymers have gained attention due to the easy access to the temperature parameter. This study investigate Poly(N-isobutyramide) (PNVIBAM) and compare it with its structural isomer, Poly(N-isopropylacrylamide) (PNIPAM).Notably, PNVIBAM exhibits a slightly higher Lower Critical Solution Temperature (LCST) than PNIPAM in aqueous solutions. This makes PNVIBAM particularly well-suited for applications requiring temperature sensitivity to the human body, such as controlled drug delivery. We investigate the swelling behavior of both polymers when employed as thin films and exposed to high humidity conditions. To assess their swelling characteristics, we employ Spectral Reflectance (SR) techniques, providing insights into how they respond to water vapor exposure and to learn about their swelling capacity. Additionally, in situ Fourier-Transform Infrared Spectroscopy (FTIR) is used to explore the hydration mechanisms in both polymers. Furthermore, Neutron Reflectometry (NR) offers crucial insights into their equilibrium swollen state and water content. This research contributes to the understanding of PNVIBAM and PNIPAM properties regarding their hydrophilic behaviour.

Speaker: Morgan Le Dû

106 P-023: Exploring Metal-Insulation for enhanced quench stability in HTS REBCO tape-based coils: a prototype study

Metal insulation technology is one of the solutions employed to enhance the quench stability of high-temperature superconductor (HTS) coils. This approach offers several advantages for quench stability. Metal substrate facilitates the detection of quenches by allowing electrical voltage signals to be easily measured across the substrate. This feature is crucial for promptly identifying quenches and preconditioning protective measures against quench-related issues. Also, the mechanism behind technology refers to the self-protection strategy to prevent the damaging effects of a quench by redirecting the electrical current away from the quench region.
We are constructing a prototype to investigate and better understand the self-protection mechanism involving metal insulation in HTS coils. This demonstrator features stainless steel as the metal component and HTS REBCO tape as the superconducting material. Using a cryocooler within a dry system and carefully installing the HTS coil, we will systematically conduct controlled experiments. Our primary objective in these experiments is to investigate quench detection and develop effective strategies that can safeguard HTS systems from issues related to quenching events. By carefully studying these mechanisms, we aim to optimize the performance and safety of HTS coils against quenching. This research holds immense importance in advancing the reliability and efficiency of HTS technology.

Speaker: Madhu Ghanathe (Technical University of Munich, Heinz Maier-Leibnitz Center)

107 P-007: Fabrication and Characterisation of Cesium- Formamidinium Lead Iodide Perovskite Quantum Dot Layers

Perovskite Quantum Dot Solar Cells (PQDSC) are very promising in contributing to the renewable energy mix of the future. Perovskite Quantum Dot Layers are used as active layer within solar cells due to the quantum confinement which occurs at crystales size below the Bohr radius.[1] Therefore they provide high power conversion efficiencies, high photoluminescence quantum yield (PLQY), a narrow photoluminescence (PL) peak, and are stable in comparisson to bulk perovskite.[1]
Furthermore, the range of usable X halides (I-, Br-, Cl-) and A cations (FA+, MA+, Cs+) enables fine control of the bandgap over the whole visible spectrum of the ABX3 perovskite structure.[14]
In this work Cesium-Formamidinium Lead Iodide perovskite quantum dot layers have been prepared using different washing processes in between several deposition steps, as well as changing the ratio between Cesium Lead Iodide PQD and Formamidinium Lead Iodide PQD. Therefore different measurement techniques (PL, microscopy, and scanning-electron-microscopy (SEM)) were used to observe the optoelectronic properties of the final film.
[1] L. Liu et al., Adv. Sci. 9.7, 2104577 (2022)
[2] L. Protesescu et al. Phys. Nano. Lett. 15.6, 3692–3696 (2015)

Speaker: Thomas Baier (TU München, Physik-Department, LS Funktionelle Materialien)

108 P-097: First automatically coaligned crystals for inelastic neutron experiments

Inelastic neutron scattering is very useful experimental method used across all scientific fields. It is mainly used for uncovering the dynamics and excitations in single crystals. Although very powerful method inelastic neutron scattering suffers from low flux scattered from sample. This can be improved by increasing volume of sample.

Traditionally, experimental physicist are coaligning big amount of single crystals in order to have higher inelastic signal [1]. This process is very time consuming and demanding [2]. For this reason the Automatic Laue Sample Aligner (ALSA) was developed.

Here we present the results of the first automatic coalignment process. We have prepared triangular lattice antiferromagnet Na$_2$BaMn(PO$_4$)$_2$ by the flux growth method. The crystals are typically 1-4mm$^2$ plates with well defined hexagonal c-axis, but a and b-axis is not possible to determine by eye, rising needs for using Laue diffractometer. ALSA robotic machine successfully coaligned 200 crystals with mass 2g and overall mosaicity spread below 1.5$^{\circ}$. The quality of coalignment was checked by scanning the plates using X-Ray Laue and also using neutron Laue technique on OrientExpress [3]. This sample was later used for investigation of the spin excitations using Cold neutron 3-axis spectrometer IN12.

[1]Chang Liu et al., Phys. Rev. Lett. 128 (2022) 137003.
[2]Private communication, Huiqian Luo.
[3]Ouladdiaf, B., et al., Physica B: Condensed Matter 385 (2006) 1052-1054.

Speaker: David Sviták (Matematicko-Fyzikální fakulta univerzity Karlovy)

109 P-052: Fractal scaling of Dairy gels: A rheology and neutron scattering study

Milk and dairy products are common food systems. One of their important constituents is casein micelles (CM) (~10-100 nm) that form extended aggregates, and further develop into a network by the process of gelation. A key structural parameter is the fractal dimension (Df) of this network[1-3]. Scattering and rheology have been explored in the past to access the relevant length scales and Df of such systems[1-6]. In the present work, dairy gels are formed using two different mechanisms: acidification, and enzymic (rennet)-induction [3,6]. The effect of mineral equilibria on enzymatic coagulation of skim milk is also explored[7]. Both the gels are investigated using oscillatory rheology, and ultra-small-angle neutron scattering (USANS) at different concentrations. Contrast variation, through the variation of H2O/D2O ratios, facilitates selective visualization of fat and protein components, and importantly the CM network during network formation. The perspectives on Df from both the techniques are compared to understand the inherent structural hierarchy.
[1] L. G. B. Bremer, et al., J. Chem. Soc., Faraday Trans. I, 85, 3359 (1989).
[2] W. C. K. Poon and M. D. Haw, Adv. Colloid Interface Sci. 73, 71 (1997).
[3] Y. Kim, et al., Appl. Sci. 12, 833 (2022).
[4] L. de Campo, et al., J. Colloid Interface Sci. 533, 136 (2019).
[5] W. H. Shih, et al., Phys. Rev. A, 42, 4772 (1990).
[6] M. Mellema, et al., J. Rheol. 46, 11 (2002).
[7] J. Bauland, et al., J. Dairy Sci. 103, P9923 (2020).

Speaker: Dr Ramya Koduvayur Ananthanarayanan (Post doctoral fellow, TUM Garching)

110 P-093: Green Solvents in Organic Solar Cells and their Influence on Performance and Stability

Lately, organic solar cells (OSCs) have gained increasing attention due to their rapidly increasing efficiencies as well as the relatively easy scalability in their manufacture. To make the manufacturing process of the bulk-heterojunction (BHJ) more environmentally friendly, increased efforts have recently been made to use halogen-free solvents, which, however, can lead to reduced efficiencies.
We investigate the changes in morphology and performance stability of PTQ-2F:BTP-4F OSCs processed from various solvents, utilising operando grazing-incidence small and wide angle X-ray scattering during illumination and solar cell operation. We further show the impact of solvents on the charge carrier generation in the respective BHJs using time-resolved transient absorption spectroscopy, analysing the connection between thin-film morphology and device performance. Also we analyze the impact of solvents on the mesoscopic distribution of small molecules within the bulk heterojunction through scattering-type scanning near-field optical microscopy.

Speaker: Lukas Spanier

111 P-069: HEiDi: Applications and Recent Developments of the Hot Single Crystal Diffractometer

HEiDi is a versatile single crystal diffractometer using unpolarized thermal and hot neutrons to provide users worldwide with high quality structure data. The applications range from studies on various magnetic compounds [Maity2021, Dutta2023, Zobkalo2023] and new battery materials [Redhammer2021] to complex framework structures [Lotti2023].

Heidi’s high neutron flux allows both studies up to a very high Q range and with strong absorbing sample environments like high pressure cells. The later was elaborated within two adjacent BMBF projects aiming to offer high pressure studies up to 10 GPa [Eich2021]. Currently, we are finalizing a small area detector (PSD) prototype to enhance HEiDi's general efficiency - faster and more comprehensive data collection - and to take a first step towards large Q studies for unpolarized neutron PDF analysis to serve the growing need on this kind of research.

[Maity2021] Maity et al. (2021); Phys. Rev. Materials 5, 014401; doi 10.1103/PhysRevMaterials.5.014401.

[Dutta2023] Dutta et al. (2023); Phys. Rev. B 107, 014420202; doi 10.1103/PhysRevB.107.014420.

[Zobkalo2023] Zobkalo et al.; Journal of Magnetism and Magnetic Materials 563, 170415; doi 10.1016/j.jmmm.2023.170415.

[Redhammer2021] Redhammer et al. (2021); ACS Appl. Mater. Interfaces, 350–359; doi 10.1021/acsami.0c16016

[Lotti2023] Lotti et al.; Am. Min., in press; doi: 10.2138/am-2023-8962

[Eich2021] Eich et al.; High Press. Res. 41[1], 88–96; doi: 10.1080/08957959.2020.1841759

Speaker: Dr Martin Meven (RWTH Aachen University, Institute of Crystallography - Outstation at MLZ)

112 P-099: High Pressure GISANS for soft matter systems: case study on polymer brush mixtures

Tuning hydrostatic pressure up to moderate (P < 1000 bar) pressure values can be crucial for understanding structure-property interplay in different disciplines, including: protein treatment in food processing, biophysics of deep-sea, processing of baroplastic polymers, polymer coating technologies for artificial joints. To the best of our knowledge, the role of pressure and thermodynamic mismatch on (1) the nanostructure of more complex brush topologies such as binary brushes and on (2) the lateral morphological characteristics of such layers in the size range 1-200 nm has so far remained elusive. We present results of high pressure Grazing Incidence Small Angle Neutron Scattering (high-P GISANS) and off-specular scattering from Neutron Reflectometry acquired at the ILL, underlining the nanoscale lateral and vertical morphologies of weakly and strongly segregated brush homopolymer mixtures under crowded conditions and confinement.

Speaker: Apostolos Vagias (FRM2 / TUM (and ILL))

113 P-047: High resolution spin-echo spectroscopy and Larmor diffraction at TRISP

We propose to significantly increase the efficiency of TRSIP for high-resolution spectroscopy and Larmor diffraction. Through optimized beam geometry and development of a spin-echo multi-detector, gain factors of 5-50 in counting time are possible. Shorter spin-echo units in combination with new radio-frequency (RF) spin-flippers will provide a larger flux on the sample. The proposed spin-echo analyzer will cover a total angle of 15°, devided into 10 individual channels. Each channel will carry an independent spin-echo unit with the ability to generate inclined field boundaries, which are required both for spectroscopy of dispersive excitations [1] and for Larmor diffraction [2]. The design of these spin-echo units inside the multi-detector follows a recent development based on so superconducting Wollaston prisms.

Speaker: Thomas Keller (MPI for Solid State Research, Stuttgart)

114 P-035: High-resolution powder diffractometer SPODI

In this presentation, we will give an overview of the current status of the powder diffractometer SPODI, its performance in user service together with future perspectives. In particular, an overview on the research areas and outcome in user service will be provided.

Speaker: Markus Hoelzel

115 P-091: High-throughput powder diffractometer ERWIN – design, capabilities and opportunities

An emergent need for high-throughput monochromatic diffraction instrument at MLZ was identified. The insturment will be addressing a large section of reciprocal space in gapless fashion and adopting sufficient dynamic range with µs time-resolution, suited for both rapid data collection and studies of small sample volumes in the range of mm3, allowing for a variety of different sample environments and having a capability to eliminate their contributions. Instrument ERWIN will bridge the gap in functionality between high-resolution powder diffractometer SPODI, engineering diffractometer STRESS-SPEC, fine-resolution FIREPOD and time-of-flight diffractometers POWTEX\SAPHIR.
In the current contribution a final concept of medium-resolution neutron powder diffraction option ERWIN at beam port SR8b at FRM II will presented. By its design the instrument ERWIN – “Energy research with neutrons” is especially adapted for structural characterization of energy materials and electrochemical storage systems by applying simultaneous bulk/spatially resolved neutron powder diffraction. Besides this a number of useful experimental options and features enabling studies of small samples using an adapted radial collimator, rapid parametric measurements as a function of external parameters, time-resolved studies etc will be discussed.

Speaker: Anatoliy Senyshyn

116 P-021: Hybridizing plasmonic nanostructures with Quantum Dots

Plasmonic nanostructures have attracted extensive research interest due to their enhanced light-matter interactions. Plasmonic induced surface plasmon resonance properties enable strong, size- and shape-dependent light absorption and scattering, as well as near-field amplification. Hybrid nanostructures containing self-assembled gold nanoparticles (Au NPs) embedded in a solid matrix of PbS quantum dots (QDs) have been developed for use in optoelectronic devices. As many studies have shown, this integration of Au NPs into PbS QDs influences the functionality of the devices by improving both their optical and electrical properties. Grazing-incidence small-angle X-ray scattering and scanning electron microscopy are used to investigate the morphology and spacing of Au NPs in the hybrid structure. Optical characterization of the different Au NP sizes is performed with UV-vis absorption measurements and (I-V) curves are taken for the investigation of the electrical properties, revealing the potential performance improvement of the optoelectronic device.

Speaker: Kyriaki Nektaria Gavriilidou

117 P-064: Imaging from meV to MeV Neutrons combined with Gamma Imaging at the NECTAR Instrument

Located at the SR10 at the FRM II, NECTAR is a versatile instrument and designed for the non-destructive inspection of various objects by means of fission neutron radiography and tomography. Compared to the Z-dependency of X-ray and gamma imaging, fission neutrons have the strong advantage of often providing similar contrast for heavy and light materials. Only few facilities around the world provide access to well collimated fast neutrons, with NECTAR at the FRM II being the only instrument that has a dedicated user program for fast neutron imaging. Aside from fast neutrons, thermal neutron as well as gamma imaging is possible by using different scintillator materials with the same detector system, extending NECTAR’s imaging capabilities to different modalities.
Here, we present the most recent upgrades to the NECTAR beam-line, including unparalleled elemental imaging capabilities with examples provided for archaeology, batteries and scintillator materials, as well as recent progress in event-mode imaging with fast neutrons.

Speaker: Adrian Losko (Technische Universität München, Forschungs-Neutronenquelle MLZ (FRMII))

118 P-085: Impact of the Environment on the PNIPAM Dynamical Transition Probed by Elastic Neutron Scattering

Hydrated proteins undergo a dynamical transition (DT) at Td ≈ 200 K. The transition is associated with the activation of protein dynamics on the ps-ns time scale, suitably detected by Elastic Incoherent Neutron Scattering (EINS). The DT has been also observed in other biomolecules and is deemed necessary for biological functionality. Surprisingly, a DT has been recently found in a non-biological system, i.e. poly(N-isopropylacrylamide) (PNIPAM). Despite its synthetic nature, PNIPAM is able to reproduce the complex solvent-macromolecule interactions at the basis of biological processes. The generality associated with the observation of the DT suggests a prominent role of the solvent. Indeed, the characteristics of the DT are strongly modified when the protein is embedded in glassy matrices of stabilizing compounds. Stabilizers inhibit the protein mobility by shifting Td toward higher temperature values and by reducing the amplitude of associated protein motions. Interestingly, the constraining action on protein fast dynamics is thought to be related to the bioprotectant ability promoted by stabilizers over longer timescales, although the microscopic details of these processes are unclear. By means of EINS techniques, we exploited the bio-mimic behaviour of PNIPAM by investigating the fast dynamics of PNIPAM chains when in presence of water/stabilizer mixtures. As in proteins, we found a tight connection between polymer dynamics and characteristics of the solvent.

Speaker: Dr Benedetta Petra Rosi (Forschungszentrum Jülich)

119 P-065: Improved surface passivation of AgBiS2 quantum dots for photovoltaic applications

AgBiS2 colloidal quantum dots (QDs) are a non-toxic alternative for the commonly used PbS QDs for photovoltaic applications. Similar to its PbS QDs, they show great promise due to a tunable bandgap and solution processing. What makes them stand out is the abundance of materials as well as a high absorption coefficient, which enables to reduce the thickness of the active layer to around 35 nm. Additionally, studies have shown that they are more stable in water and can effectively harvest photons in the near-infrared part of the solar spectrum. One of major issues that impede the development of AgBiS2 based photovoltaics is QD surface defects induced recombination losses. Here, we aim to improve the surface passivation of individual QDs and improve the charge transport in the QD films using surface ligand treatment with ZnI, mercaptocarboxylic acid (MPA) and TBAI as surface ligands. The optical and electrical properties of corresponding QDs films are characterized utilizing FTIR, XPS and UPS techniques, and further the corresponding device performances are investigated.

Speaker: Petar Lovric (TUM)

120 P-112: In situ GISAXS investigation of sputtering IZO thin film for optoelectronic applications

Transparent conducting oxide (TCO) thin films have been studied intensively for optoelectronic devices, such as photodetectors, photovoltaics and light emitting diodes (LEDs). Among the several TCO thin films, zinc doped indium oxide (IZO) has received much attention as interface layer in optoelectronic devices due to its excellent electrical conductivity, optical transmittance, high thermal/chemical stability, low cost and low deposition temperature. Here, ITO glass and spin coated ZnO on ITO glass are used as the templates for IZO thin film deposition via DC magnetron sputtering technique. The growth dynamics of IZO film on these two templates are respectively investigated via grazing small angle x-ray scattering (GISAXS) characterization, and the morphology and optoelectrical properties of final films are further investigated.

Speaker: Huaying Zhong

121 P-033: In situ GISAXS printing of biotemplated titania nanostructures

Biotemplating is an effective method of nanostructuring hybrid
inorganic-organic materials. This approach allows the tuning of material properties like porosity or domain sizes. Therefore, parameters like
the electronic conductivity can be adjusted for different applications.
In this work, differently structured Titania thin films are investigated
for application in thermoelectric generators. Beta-lactoglobulin is a
bovine whey protein that is used as a template during sol-gel synthesis.
The Seebeck effect allows the conversion of waste heat into electrical
energy. State of the art thermoelectric materials are rare, toxic and
expensive. Biotemplated titania could provide a non-toxic and abundant alternative. To investigate the different titania morphologies, in
situ GISAXS, GIWAXS and SEM are used. In situ GISAXS printing
enables a time resolved investigation of the structure formation,
domain sizes and domain distances. UV-Vis and Pl are used to
analyze differences in the optical properties of the thin films. These
structural and optical changes are then correlated with measurements
of the Seebeck coefficient and the electrical conductivity.

Speaker: Linus Huber (TU München)

122 P-040: In situ Grazing-Incidence Small-Angle X-ray Scattering Observation of TiOx Sputter Deposition for Perovskite Solar Cells Application

It is crucial to suppress the non-radiation recombination in the hole-blocking layer (HBL) and at the interface between the HBL and active layer for performance improvement. Herein, TiOx layers are deposited onto a SnO2 layer via sputter deposition at room temperature, forming a bilayer HBL. The structure evolution of TiOx during sputter deposition is investigated via in situ grazing-incidence small-angle X-ray scattering. After sputter deposition of TiOx with a suitable thickness on the SnO2 layer, the bilayer HBL shows a suitable transmittance, smoother surface roughness, and fewer surface defects, thus resulting in lower trap-assisted recombination at the interface between the HBL and the active layer. With this SnO2/TiOx functional bilayer, the perovskite solar cells exhibit higher power conversion efficiencies than the unmodified SnO2 monolayer devices.

Speaker: Xiongzhuo Jiang (TUM School of Natural Sciences)

123 P-024: In-situ neutron diffraction and electron microscopy to study deformation mechanisms in Ni-based superalloys

The polycrystalline Ni-based superalloy VDM Alloy® 780 is a further development of the Alloy 718 which is limited in the service temperature of gas turbines to around 650°C. The most important differences between these two alloys are essentially the replacement of Fe by Co and a higher Al–content in combination with a lower Ti-content in VDM Alloy® 780. Tensile loading and unloading experiments were carried out with a newly developed testing machine at the Stress-Spec instrument of MLZ to investigate the deformation behavior at 25 and 500°C. Furthermore, a detailed microstructural investigation was performed by electron microscopy before and after testing to correlate the macroscopic mechanical properties with micromechanical deformation behavior in various oriented grains. The deformation mechanism in the differently oriented grains is primarily dislocation motion and shearing of the Gamma Prime precipitates at both investigated temperatures.
[1] F. Kümmel, A. Kirchmayer, C. Solis, M. Hofmann, S. Neumeier, R. Gilles, Metals 2021, 11, 719.

Speaker: Ralph Gilles

124 P-017: Incorporation and localization of magnetic nanoparticles in printed hybrid thin nanoparticle-diblock copolymer films investigated by GISAXS

Ordered magnetic hybrid thin films composed of a diblock copolymer (DBC) and magnetic nanoparticles (MNPs) are interesting due to the mixing of properties from the organic and inorganic precursors. The unique attributes of these hybrid films make them attractive for use in applications ranging from magnetic sensors to magnetic data storage devices. In this study, thin DBC films of polystyrene-block-poly(methyl methacrylate) (PS-b-PMMA) are investigated as scaffolds for the MNPs nickel oxide (NiO) and cobalt ferrite (CoFe2O4). The thin films are printed using a slot-die coating technique and the evolution of the final film morphology is tracked in situ by grazing incidence small-angle X-ray scattering (GISAXS). Analysis of the GISAXS experiments, complemented by the real-spacing imaging method atomic force microscopy (AFM), reveals the selective incorporation of the CoFe2O4 MNPs into the PS domains while the further addition of NiO MNPs does not disturbed the DBC nanostructure. The temperature dependent magnetic properties of the thin hybrid films are investigated with a SQUID magnetometer. Films containing only CoFe2O4 show expected behavior as the coercivity and remanence increase with decreasing temperature. Upon addition of NiO, the mixed hybrid thin films show a unique pinched hysteresis curve resulting in an increase in coercivity and squareness when compared to the single MNP films.

Speaker: Christopher Everettt (TU München, Physik-Department, LS Funktionelle Materialien)

125 P-053: Influence of Photoswitchable Molecules on the Swelling Behavior of Thermoresponsive Poly(Dimethylacrylamide) Films in Water Vapor under UV-Irradiation

In this study, we investigated the swelling characteristics of p(AzAm-co-DMAm) and p(AzPyAm-co-DMAm) thin films in both isomer states of the photoswitchable molecules azobenzene (Az) and azopyrazole (AzPy). In thin films, irradiation of the chosen photoresponsive polymers can influence the swelling behavior in water vapor and provide a method to precisely control water uptake, expansion, and morphology on the nanoscale. This makes them promising candidates for applications such as light sensors, photo-actuators and drug-delivery systems. From in situ time-of-flight neutron reflectometry measurements with high temporal resolution at the D17 instrument at ILL, we obtained depth-resolved data about the water distribution during swelling, drying and irradiation in the dry and swollen state, using our custom-built chamber which allows for precise control of humidity. We show that photoswitchable molecules in thin polymer films provide an effective method of altering macroscopic bulk properties in functional materials.

Speaker: David Kosbahn (TUM E13)

126 P-031: Influence of process parameters on microstructure and residual stress in alloys produced by additive manufacturing.

Metal Additive manufacturing (AM) allows printing structures of almost any complexity.
Therefore, it is an uprising technique in various industrial sectors like automotive and aerospace. Nevertheless, in the manufacturing method of laser powder bed fusion (LPBF) the used process parameters have a high influence on the final part. They impact texture, residual stress and also the tensile properties. To achieve consistent material characteristics, a pro-found understanding of the process parameter influence is needed.

In the current presentation, we investigate the evolution of residual stress, texture and the tensile properties of additively manufactured samples as a function of build direction and diameter. Two different alloys, 316L and AlSi11Mg0.5, are used as sample material. They are both widely utilized in AM and form a fcc structure. But 316L has only one phase and is highly anisotropic, whereas AlSi11Mg0.5 is a nearly isotropic two-phase metal.
This study uses high energy synchrotron X-rays to assess the residual stress and the texture of the different samples. Furthermore, in-situ tensile tests were conducted to study the elastoplastic behaviour and the dislocation densities. The results are evaluated with respect to the different process parameters. In addition, a comparison between the two alloys is conducted to determine how much the material-specific properties affect the finished component.

Speaker: Michael Hofmann

127 P-086: Interface stability of active layers on conductive nanopaper for organic thin-film photovoltaics

Flexible organic photovoltaics make use of polymer-based materials. A novel development is to combine cellulose nanofibrils (CNF) and poly(3,4-ethylenedioxythiophene):polystyrene sulfonate (PEDOT:PSS) for fabricating sustainable, flexible, multifunctional and stable electrodes (so-called ‘power-paper’). When depositing the active layer, thermal annealing is a necessary step for optimizing the morphology of the active layer. With the CNF/PEDOT:PSS thin-film being porous, it is thus crucial to observe the assembly, layering, and the interactions at the interface active layer/power-paper directly. We hence investigated the interface stability of a functional P3HT:PCBM stack (deuterated and non-deuterated) on a CNF/PEDOT:PSS thin-film after thermal annealing (T = 170°C, inert atmosphere) and present our results obtained using neutron reflectometry at the Chinese Spallation Neutron Source (CSNS) at beamline 02.

Speaker: Stephan Roth (DESY / KTH)

128 P-003: Investigation of radiation exposure on organic solar cell for space application

As space technologies and space missions develop rapidly, the demand for solar cells dedicated to space applications is increasing. Space solar cells face more critical challenges than before. Higher gravimetric Power Density and better radiation resistance are the primary keys. This project aims to investigate the degradation of organic solar cells in the space environment. Based on previous work regarding deploying Organic Solar Cells (OSC) in space on a suborbital rocket, we work on long-term experiments to study the degradation mechanisms in space. For that, we do space environmental simulations on the ground to prepare for long-term experiments in orbit. The main objective is to emulate significant parameters that can reduce the performance of our cells. Organic solar cells used in space exploration devices are mainly exposed to Radiation, which causes damage to the morphological and chemical structure of the organic bulk heterojunction through ionization. It is, therefore, interesting to study the impact of ionising radiation to evaluate the possibilities and prospects for optimising the performance of solar cells in space. A gamma-ray radiation test is conducted to investigate the morphology changes at different total ionizing doses. This will give us a clear idea of how space radiation will affect the structure of our OSCs and how we can reduce radiation damage.

Speaker: Tarek Azzouni (Technical University of München)

129 P-014: Investigation of the Structure of Organic Solar Cells for Space Application and Degradation Due to Mechanical Stress

Organic solar cells (OSCs) are emerging as a promising candidate for space application because of their high gravimetric power density and flexible nature, which would save fuel and space in a rocket flight.
However, several challenges must be addressed for OSCs to fulfil their potential in space. Currently, the main problem is the reduction of the degradation due to the harsh conditions during the space flight.
Following a previous project which deployed OSCs in space on a suborbital rocket, our group aims to further investigate the degradation of OSCs in the space environment by reproducing the conditions separately. This work will focus primarily on degradation due to intense mechanical stress. OSCs are exposed to accelerations up to 20 g and strong vibrations during rocket launch and re-entry. This will be simulated with a shaker stress test followed by an investigation of the changed properties of the cell.
The examined OSCs consist of a BTP-4F and PTQ-2F bulk hetero junction, a zinc oxide hole blocking layer, a molybdenum oxide electron blocking layer, a silver anode and an ITO cathode. They are fabricated on glass and flexible PET substrates.
Another topic of this work is to better understand the effects of annealing BTP-4F and PTQ-2F. This leads to a tuning of the bandgap and the absorption spectrum.
As research continues to address material properties and degradation, OSCs have the potential to become a vital energy source for future space exploration missions.

Speaker: Mr Jan Darsow

130 P-044: Investigation on structural, electrical and magnetic properties of Gd3+ doped magnesium ferrite (MgFe2O4) ceramics

Properties of Gd3+ rare earth ion incorporated MgFe2-xGdxO4 (0 =< x =< 0.16) ceramics prepared from powders using combustion technique with DL- alanine fuel are investigated. Re-arrangement of cations in the unit cell due to Gd3+ substitution for Fe3+ in MgFe2O4, and the consequent effects on the electrical and magnetic properties are discussed. Improvements in electrical resistivity with increasing Gd3+ content are shown to be significant, and dielectric response is analyzed using impedance and electric modulus. The X-ray density increases while the lattice parameter decreases slightly with increase of Gd3+ ion content in up to x = 0.08 in the phase pure MgFe2-xGdxO4 (0 =< x =< 0.08) powders. However, the measured bulk density in sintered ceramics decreases from 4.26 to 3.78 g cm-3, and porosity increases from 5.12 % to 18.58 %. In comparison to pure MgFe2O4 improvement is seen for an optimum Gd3+ concentration (x = 0.02) i.e., Mg2Fe1.98Gd0.02O4 ceramics. The MgFe2O4 ceramics having porosity 5.12%, while Mg2Fe1.98Gd0.02O4 ceramics having porosity 5.38 %, while electrical resistivity improves by ~100 times, the dielectric constant (ε'=14.3), loss factor is low (tan δ ~ 0.003) at 1MHz.

Speaker: Dr Sudhanshu Kumar (Forschungs-Neutronenquelle Heinz Maier-Leibnitz (FRM-II), Technical University of Munich (TUM) and Heinz Maier-Leibnitz Zentrum (MLZ), Lichtenbergstr. 1, D–85748, Garching, Germany.)

131 P-101: KCl modulated D2O Hydration and Subsequent Thermoresponsive Behavior of Poly(sulfobetaine)-Based Diblock Copolymer Thin Films

The salt effect of KCl on D2O hydration and subsequent thermoresponsive behavior of diblock copolymer (DBC) thin films, which feature a short zwitterionic poly(4-((3-methacrylamidopropyl) dimethylammonio) butane-1-sulfonate)) (PSBP) block and a long nonionic thermo-responsive poly(N-isopropylmethacrylamide) (PNIPMAM) block, is studied by in situ spectral reflectance (SR) and time-of-flight neutron reflectivity (ToF-NR) in combination with isotope sensitivity. The solvation-triggered phase transition upon D2O hydration and subsequent heating is probed in situ by Fourier transform infrared spectroscopy (FT-IR). Besides, the migration and/or aggregation of KCl domains inside the DBC thin films is also demonstrated by complementary methods, namely, X-ray reflectivity (XRR) and atomic force microscopy (AFM).

Speaker: Peixi Wang (Workgroup Polymer Interfaces, TUM Department of Physics, Technical University of Munich)

132 P-025: KOMPASS – the polarized cold neutron triple-axis spectrometer optimized for polarization analysis

KOMPASS is a new polarized cold-neutron three axes spectrometer (TAS) recently built at the MLZ in Garching. The instrument is designed to exclusively work with polarized neutrons and optimized for zero-field spherical neutron polarization analysis for measuring all elements of the polarization matrix. In contrast to other TASs, KOMPASS is equipped with a unique polarizing guide system. The static part of the guide system hosts a series of three polarizing V-cavities providing a highly polarized beam. The exchangeable straight and parabolic front-end sections of the guide system allow adapting the instrument resolution for any particular experiment and provide superior energy- and Q-resolution values when compared with the existing conventional guide and instrument concepts [1, 2]. In combination with the end position of cold neutron guide, the large doubly focusing HOPG monochromator and analyzer, the V-cavity for analysis of polarization of scattering beam, the KOMPASS TAS will be very well suited to study various types of weak magnetic order and excitations in variety of complex magnetic structures and indeed first successful experiments on chiral magnets or very small crystals could already be performed.
[1] M. Janoschek et al., Nucl. Instr. and Meth. A 613 (2010) 119.
[2] A. C. Komarek et al., Nucl. Instr. and Meth. A 647 (2011) 63.
The construction of KOMPASS is funded by the BMBF through the Verbundforschungsprojekt 05K19PK1.

Speaker: Dr Dmitry Gorkov (FRM2)

133 P-082: KWS-3 very small-angle neutron scattering focusing diffactometer at MLZ

KWS-3 is a very small angle neutron scattering diffractometer operated by JCNS at Heinz Maier-Leibnitz Zentrum (MLZ) in Garching, Germany. The principle of this instrument is one-to-one imaging of an entrance aperture onto a 2D position sensitive detector by neutron reflection from a double-focusing toroidal mirror. In current state, KWS-3 is covering Q-range between 3·10-5 and 2·10-2 Å-1 and used for the analysis of structures between 30 nm and 20 μm for numerous materials from physics, chemistry, materials science and life science, such as alloys, diluted chemical solutions, hydrogels and membrane systems. Within the last few years we have finalized several big “evolutionary” projects; we have completely re-designed and commissioned the main components of the instrument: selector area, mirror positioning system, main sample station at 10m, beam-stop system; implemented new sample stations at 3.5 and 1.3m, second (very-high resolution) detector, polarization and polarization analysis systems; adapted the instrument to almost any existing/requested sample environment like 6-position Peltier furnace (-25°C to 140°C), high-temperature furnace (< 1600°C), cryostats/inserts (>20 mK), liquid pressure cell (<5 kBar/10-80°C), CO2/CD4 gas pressure cell (<0.5 kBar/10-80°C), humidity cell/generator (5-95%/10-90°C), magnets (horizontal < 3T, vertical < 2.2T), Bio-logic® multimixer stopped flow (5-80°C), rheometer Anton paar (tangential/radial) etc.

Speaker: Dr Vitaliy Pipich (Jülich Centre for Neutron Science JCNS at Heinz Maier-Leibnitz Zentrum MLZ Forschungszentrum Jülich GmbH)

134 P-083: Less is more: tiny amounts of insoluble multi-functional microporous additive plays a big role in lithium-ion batteries

Binders play an important role in multi-component electrodes for rechargeable batteries, which suffer from poor electronic and ionic conductivity. Binder-free electrodes provide another way to resolve problems, where sophisticated structure construction is required. A new concept of electrode processing alternative to binder-containing and binder-free electrodes was established. A multi-functional PIM-1 (a polymer with intrinsic microporosity) additive was used instead of PVDF to form mechanically processable Li secondary battery cathodes. Due to its unique nanoporous structure built by the spiro-containing rigid aromatic polymer chain, only a tiny amount of PIM-1 in the LiNi0.8Co0.1Mn0.1O2 cathode is needed to retain good performance, far below the typical composition for PVDF. Homogeneous dispersion of carbon black is achieved by PIM-1, which stabilizes the electrode and increases the electronic conductivity. Different from PVDF, mechanical buffering by stiff PIM-1 yields crack-free electrodes after cycles. Moreover, an inorganic rich cathode-electrolyte interface layer is formed via a desolvation process promoted by PIM-1, because of its strong binding ability with lithium ions, which is beneficial for cyclic stability and rate capability.

Speaker: Ruoxuan Qi (Technical University of Munich)

135 P-054: MARIA – The high-intensity polarized neutron reflectometer of JCNS

The high-intensity reflectometer MARIA of JCNS is installed at the neutron guide hall of the FRM II reactor in Garching and it is a state of the art reflectometer at a constant flux reactor. It gives the opportunity to investigate specular reflectivity curves in a broad dynamic range including off-specular scattering and GISANS measurements. The availability of a polarised neutron beam and the integration of a time-stable ³He polarization spin filter based on Spin-Exchange Optical Pumping (SEOP), together with a multitude of offered sample environments permits the use of the instrument in a wide range of studies ranging from nano-magnetism to biology. In this contribution we highlight the technical aspects of the instrument and also the potential research opportunities it gives to the user.

Speaker: Alexandros Koutsioumpas (JCNS)

136 P-032: Materials Science Diffractometer STRESS-SPEC – current status and developments

STRESS-SPEC is the dedicated diffractometer for materials science applications at MLZ. It offers high thermal neutron flux and is mainly used for fast residual strain and texture (bulk, local or gradient) measurements [1, 2]. Recent upgrades include a new detector system developed in-house, a new fully automatic slit system for gauge volume definition of the monochromatic beam, and a quenching / deformation neutron dilatometer. As a further development and in line with the new slit system we developed a new radial collimator to shape the gauge dimensions of the monochromatic beam impinging on the sample.
STRESS-SPEC has pioneered the use of robotic sample manipulation [2, 3] and improvements of the position accuracy of this device through a new adaptive control system will be shown as well.

References

[1] M. Hofmann et al, Mater. Sci. Forum. 524-525, 211-216 (2006)
[2] H.-G. Brokmeier et al, Nucl. Inst. & Meth. in Phy. Res. A 642, 87-92 (2011)
[3] C.R. Randau et al, Nucl. Inst. & Meth. in Phy. Res. A 794, 67-75 (2015)

Speakers: Michael Hofmann, Dr Weimin Gan (Helmholtz-Zentrum Hereon)

137 P-061: Mesoporous Film Morphology: Factors and Insights from Sol-Gel Coatings

Mesoporous films consisting of zinc titanate have high potential applications in photocatalysis, solar cells, and sensors due to tailoring their semiconductive properties. In the present work, we investigate the morphologies of mesoporous zinc titanate films obtained by changing the ratio of two inorganic precursors after calcining hybrid films consisting of organic-inorganic materials. The amphiphilic diblock copolymer poly(styrene)-b-poly(ethyleneoxide) PS-b-PEO self-assembles into core-shell micelles in a mixture of N,N-dimethylformamid/hydrogen chloride playing the role as structure directing template. The inorganic precursors, zinc acetate dehydrate and titanium tetraisopropoxide, are loaded in the micellar shell due to hydrogen bonds between PEO and precursors. We use slot-die and spin-coating methods to prepare hybrid films and investigate the influence of the different deposition methods on the film morphologies. Moreover, we investigate how mesoporous structures and crystal phases depend on calcination temperature, concentration, and the ratio of two precursors. The morphologies of the hybrid films are characterized using grazing incidence small-angle X-ray scattering (GISAXS) and scanning electronic microscopy (SEM). The film thickness, crystal phase, chemical composition, and optical properties are characterized using X-ray reflectivity, X-ray diffraction, Fourier transform infrared spectroscopy, and ultraviolet-visible spectroscopy, respectively.

Speaker: Yanan Li

138 P-043: Microstructure and texture evolutions of γ-TiAl alloy under hot compression via in-situ diffraction

The third generation β-solidifying TNM alloys with (α2+γ) lamellar microstructures have been considered excellent candidates for modern turbine blades due to their low density, high specific strength and stiffness, excellent creep resistance, and good corrosion resistance. It has been proved that orienting the γ lamellae to the direction of the load can significantly increase the mechanical properties of the alloys, thus making lamella orientation control (texturization) an interesting topic for property optimization.
In our work, high temperature compression experiments were performed firstly to intent to texturize the alpha phase through optimization of compressive speed and strains. An optimum basal fiber texture was obtained for alpha phase. Second, the effects of cooling rate, and extern applied load on the process from alpha to gamma transition was studied to successful obtaining the lamellar structure.
Meanwhile, in-situ high-energy synchrotron radiation diffraction experiments were conducted on both the compressing and cooling processes using the unique dilatometer at HEMS, DESY. Diffraction rings analysis for phase transition and microstructure evolution will be presented together with the EBSD investigation in this contribution.

Speakers: Mohamed KEITA, Dr Weimin Gan (Helmholtz-Zentrum Hereon)

139 P-088: Modelling backscattered positron capture at the coincidence Doppler broadening spectrometer

The coincidence Doppler broadening spectrometer (CDBS) at the MLZ provides state-of-the-art, depth dependent detection of defects and chemical composition at the annihilation site. A monoenergetic positron micro-beam (50 µm FWHM) is guided onto a sample where positrons may thermalise and annihilate with electrons. The Doppler broadening of the characteristic 511 keV annihilation peak is measured by observing both emitted photons simultaneously.
The measurement quality depends on the size and energy of the beam, both of which are monitored and controlled [1]. However, up to ~ 40% of the incident positrons are backscattered at the sample surface, resulting in a distribution of positrons with a large spread in energy and scattering angle. The annihilation events occurring when these backscattered positrons return to the sample or annihilate in experimental hardware contribute unwanted signal to the measured spectrum which cannot be removed in data processing.
We present simulations and hardware design for an upgrade to the CDBS which will allow backscattered positron capture. We use an in-house particle tracking code to design a positron dump that will capture backscattered positrons at a negatively biased electrode and will be shielded from detector lines of sight. This will remove the unwanted signal from the detected spectrum and improve the quality of CDBS data.
[1] Gigl, T. et al. (2017). New Journal of Physics, 19(12), 123007.

Speaker: Danny Russell (FRM2)

140 P-072: Neutron and synchrotron diffraction studies to understand the mechanism and the influence of hydrogen on the microstructure of superalloys.

Hydrogen will play a major role as a renewable and carbon-free energy carrier. This accordingly also requires the investigation of materials coming in contact with hydrogen in energy conversion devices, e.g. gas turbines. However, such materials, usually nickel-based superalloys, suffer in strength and durability through the so-called hydrogen embrittlement (HE) which is yet to be fully understood. Especially, crystallographic studies of embrittled samples are yet scarcely carried out. Here, the influence of different hydrogen treated advanced alloys such as Alloy X or the newly developed VDM® Alloy 780 is investigated. The alloys are hydrogen loaded electrochemically or via high pressure and high temperature treatments. These samples are subsequently investigated by neutron and high-energy X-ray diffraction and supported by microscopic investigations and mechanical testings. Depending on the loading method, cell parameter reductions or cell parameter expansions are observed because of ordering effects or the incorporation of hydrogen in interstitial sites of the fcc lattice.

Speaker: Dr Alexander Mutschke

141 P-046: Neutron reflectometry with micro-second time resolution

We propose to implement a new modulation technique at NREX adding time resolution to polarized neutron reflectometry (PNR). The new technique is based on intensity modulation by a radio-frequency (RF) spin flipper, and shares some basic concepts with the MIEZE spin-echo technique. The aim is to resolve the kinetics of the nuclear and magnetic scattering length densities in periodic processes with a time resolution of a few micro-seconds, corresponding to an improvement of two orders of magnitude compared to conventional techniques. One main application of this new technique will be the study of so called magneto-ionic (MI) materials, which have a high potential in ultra-low-power neuromorphic computing applications. The electric and magnetic properties of magneto-ionic materials can be tuned or switched by a small gating voltage, which drives the transport of ions perpendicular to the layer boundaries. Oxygen, nitrogen, lithium, or hydrogen were used as mobile ions in MI materials, where hydrogen shows the highest mobility and thus allows for fast switching. Time resolved PNR will be a unique tool to study the switching process in MI materials in-situ, as both the hydrogen and the magnetization profiles can be determined with high accuracy. In addition, H/D contrast variation will permit to distinguish hydrogen migration from concurrent parasitic transport of other ions such as oxygen, a process which typically occurs in oxide materials.

Speaker: Thomas Keller (MPI for Solid State Research, Stuttgart)

142 P-105: New options on the polarized neutron single crystal diffractometer POLI at MLZ

Polarized neutron diffraction is a powerful tool for studying condensed matter physics and to probe the spin and orbital properties of unpaired electrons. POLI is a polarized neutron single crystal diffractometer built on the hot neutron source at MLZ. Currently three standard setups are implemented on POLI: 1) zero-field spherical neutron polarimetry using CRYOPAD; 2) polarized neutron diffraction in magnetic fields; 3) non-polarized diffraction under various conditions.
We recently implemented a new actively shielded asymmetric split-coil superconducting magnet with a maximal field of 8T. The magnet is designed to facilitate polarized neutron diffraction with low stray fields, a large opening (30̊ vertical) and a large sample space suitable for e.g., piezo goniometers, and pressure cells. We also built a compact-size solid-state supermirror bender polarizer optimized for short neutron wavelengths to provide high neutron polarization in the vicinity of the magnet. An in-situ SEOP polarizer and analyzer will be available soon which maintains high levels of neutron polarization and intensity over long periods of time. The SEOP polarizer are well shielded magnetically and can be used with the large magnet. Transferring the BIDIM26 area detector of size 26cm by 26cm from LLB to MLZ is in progress [3].

[1] V. Hutanu, J. Large-Scale Res. Facil. 1, A16 (2015).
[2] V. Hutanu et al., IEEE Trans. Magn. 58, no. 2, pp. 1-5, (2022).
[3] A. Gukasov et al., Physica B 397, 131 (2007).

Speaker: Jianhui Xu (RWTH Aachen, JCNS)

143 P-015: New RF spin flippers for the MIEZE spectrometer RESEDA

Neutron resonant spin-echo (NRSE) and modulation of intensity with zero effort (MIEZE) are variants of the classical neutron spin-echo (NSE) technique, where the large static magnetic field precession coils are replaced with pairs of resonant spin flippers. They operate by producing a static magnetic field and a perpendicular radio frequency (RF) field to achieve a resonant neutron spin flip. This shifts the challenge of improving resolution from achieving strong, homogenous static fields, as is necessary for classical NSE towards the design and optimization of the RF coils and their corresponding matching circuitry.

Recent improvements at the RESEDA instrument at the Forschungs-Neutronenquelle Heinz Maier-Leibnitz (FRM2) have seen the replacement of the static field coils surrounding the RF coils with superconducting coils, which can reach higher fields, pushing the current RF flippers towards their limits. This necessitates the optimization of the RF flippers.
Here, we will discuss how we optimized the RF flippers using the simulation software “COMSOL Multiphysics” and we will present the design that resulted from these simulations.

Speaker: Pavel Daskalov

144 P-081: Operando neutron diffraction experiments in order to investigate the lithiation and ageing mechanism of industrial scale multi-layer 5 Ah pouch cells with LiNi0.8Co0.15Al0.05O2 cathodes and silicon anodes

With each year, the demand for Li-ion batteries is increasing – whether it is for industrial applications or electric vehicles – and improving battery performances remains one of the main goals of the research. Currently, switching to materials offering higher energy is one approach to achieve higher capacities. Silicon has gained much interest as anode material due to its high specific capacity of 3579 mAh/g compared to conventional graphite. However, pure silicon suffers from severe volume changes during lithiation, inducing mechanical stresses that can result in the failure of the battery.
Here, the lithiation mechanism and aging behavior of silicon anodes and LiNi0.8Co0.15Al0.05O2 (NCA) cathodes in multi-layer 5 Ah pouch cells were studied with neutron diffraction at the Wombat instrument at ANSTO. The batteries were fabricated on the research production line of the iwb institute at TUM to replicate the conditions of commercial cells as closely as possible. After formation and stabilization, uncylced cells were compared to a cylced cell at a state of health of 60 percent.
Due to aging, the capacity is decreased, which can be seen in the evolution of the cell parameters of NCA as well. Hereby, the c and a parameter of the aged cell are moving in a smaller window compared to the uncycled cell. Furthermore, it could be seen that the peak positions of NCA are shifting during the relaxation phase after charge indicating that the structure of NCA is changing.

Speaker: Thien An Pham

145 P-108: Operando study on structure-activity relationship between electrolyte components and electrochemical performance for all-solid-state lithium-ion batteries

All-solid-state lithium-ion batteries (ASSLIBs) have received extensive attention as one of the most promising power sources for flexible and wearable electronics, mainly because of their high flexibility, high energy density and reliable safety. However, the practical application of ASSLBs has been hindered by the poor interfacial stability and inferior ionic conductivity. Solid polymer electrolytes (SPEs) exhibit great potential in developing solid-state batteries, specifically for PEO and PEO-based derivatives, because of their superior interfacial compatibility, outstanding solubility against lithium salts, wide electrochemical windows and high ionic conductivity. At the same time, solid fillers, as an important component in SPEs, play a crucial role in determining the overall electrochemical properties. Several strategies have been adopted to address the above issues, nevertheless, the SPEs degradation mechanism is still not clear and needs to be further studied. As a consequence, we start from PEO-based materials and prepare SPEs by adding plastic additives and solid fillers with good structure. The structure-activity relationship between the component structure of the electrolyte and the electrochemical performance is elucidated by a combination of electrochemical characterization and morphological structural characterization.

Speaker: Yingying Yan (Lehrstuhl für Funktionelle Materialien, Physik-Department, TU München)

146 P-063: Optimization of printed Organic Solar Cells

Organic solar cells (OSCs) have been attracting a lot of attention in research in recent years because to their low weight, non-toxicity, and high efficiency. OSCs are particularly appealing to industry due of their easy solution-based fabrication process and therefore the possibility for thin and flexible solar cells. Due to the solution-based fabrication process, the OSCs can be upscaled with low waste deposition technologies like printing. Being fast and using minimal material, slot-die coating is thereby a very promising technique. During this study we optimize the slot-die printing process of OSCs under ambient conditions and in a nitrogen atmosphere and investigate their properties compared to spin-coated OSCs. The differently manufactured OSCs will be compared with measuring techniques like spectroscopy and real-space imaging in combination with X-ray scattering methods.

Speaker: Christoph Lindenmeir

147 P-045: Optimization of the in-line SEC-MALS at the Small-Angle Neutron Diffractometer KWS-2

The small-angle neutron scattering (SANS) diffractometer KWS-2, operated by the Jülich Centre for Neutron Science at Heinz Maier-Leibnitz Zentrum in Garching, is equipped with an in-line size exclusion chromatography (SEC) followed by the multi-angle light scattering (MALS) machine. The established SEC-SANS-MALS setup facilitates the in-situ fractionation of the sample solution, the collection of SANS data, and the analysis of molar mass, subsequently. In addition, a UV-vis spectrometer is installed on the SANS flow cell holder, to examine the sample concentration during SANS data collection. In the present work, the performance of the setup is assessed and optimized, and the work on signal synchronization aims at better management of the multi-task measurement.

Speaker: Jia-Jhen Kang (Jülich Centre for Neutron Science (JCNS) at Heinz Maier-Leibnitz Zentrum (MLZ))

148 P-095: Positronium Formation on Polymers Studied by Low-Energy Positrons

A low-energy monoenergetic positron beam can be used to implant positrons near the surface of materials. In polymers and in particular in porous materials positrons can form positronium (Ps). Even at greater implantation depths Ps can diffuse back to the surface and be emitted if the material has an open porous structure, i.e., the pores create a path to the outside. Therefore, we can qualitatively compare the porosity of materials by measuring the amount of freely decaying Ps depending on the positron implantation energy. By using a new algorithm we optimized the magnetic guiding of our monoenergetic laboratory positron beam in order to achieve a sharp focus at lowest implantation energies. We performed first measurements on the 3-gamma decay of ortho-Ps in order to study the Ps formation at the surface of PMMA and Kapton, forming a high and low amount of Ps, respectively.

Speaker: Maximilian Suhr (Heinz Maier-Leibnitz Zentrum (MLZ), Technische Universität München)

149 P-036: PUMA: Thermal neutron three axes spectrometer

Thermal neutron three axes spectrometer PUMA is characterized by a very high neutron flux as a result of the efficient use of focusing techniques. An innovative option of the spectrometer is the multianalyzer/detector system, which allows a unique and flexible type of multiplexing. Using this option, a scattering angle range of 16° can be measured simultaneously and flexible Q-ω paths can be realized without repositioning the instrument. The typical scientific applications of PUMA are studies of phonons and magnons. Furthermore, a unique feature of the instrument is the possibility to perform stroboscopic, time resolved measurements of both elastic and inelastic signals on time scales down to the microsecond regime. Using this technique, the sample is periodically perturbed by an external variable such as temperature, electric field, etc. The signal is then recorded not only as a function of momentum and energy transfer, but also given a time stamp, relative to the periodic perturbation. Since 2021, the Neutron Scattering Group of the Institute of Quantum Materials and Technologies (IQMT, www.iqmt.kit.edu) of the Karlsruhe Institute of Technology (KIT) has been jointly operating the PUMA three-axes spectrometer at MLZ within the framework of a collaboration contract. The purpose of the collaboration is to promote the scientific program, support the user program and develop instrumental capabilities.

Speaker: Jitae Park (MLZ, TUM)

150 P-049: QtiSAS: SANS data analysis and reduction software

QtiSAS [1, 2] is an open-source cross-platform software designed for the graphical visualization, reduction, analysis, and fit of data. At Jülich Centre for Neutron Science (JCNS) it is designed particularly to work on data produced by small-angle neutron scattering (SANS) instruments, however it could also be an alternative to proprietary scientific software like Origin or Igor Pro.

QtiSAS has following SANS tools:
- DAN is SANS data reduction interface which allows to define a new or modify an existing data-reduction-protocol inside of the running program.
- ASCII.1D is powerful import/export tool for the radial averaged SANS datasets that allows conversion to other SANS-presentation (Guinier, Zimm, Porod, etc), data filtering, arithmetic operations.
- SVD is singular value decomposition. Scattering curves of a multicomponent system measured by applying a set of the scattering contrasts could be decomposed to the individual scattering functions and corresponding cross-terms.
- Fit.Curve(s) is the fitting interface which allows to a user to fit radial averaged datasets taking into account polydispersity of any parameter of a fitting function and/or the instrument resolution.
- Fit.Compile is user-friendly interface to create and compile a fit function of any complexity using custom C++, but there is also an option of calling of FORTRAN functions.

1. https://www.qtisas.com/
2. https://iffgit.fz-juelich.de/qtisas/qtisas

Speaker: Konstantin Kholostov (Forschungszentrum Jülich GmbH)

151 P-075: Quantum condensed matter under extreme condition

Kagome magnet RMn6Sn6, [R=Gd-Er] are extensively studied in search of nontrivial magnetic and topological states [1,2]. The strong magnetic coupling in between the metal ion Mn in pristine Kagome bilayers and the rare earth R in triangular lattice framework generates the complex magnetic phases which are favorable for correlated topological states [3,4]. Here in this work, the pressure tunability of the magneto crystalline anisotropy that controls the spin quantization axis of Mn in Kagome layer will be discussed by our pressure dependent in-house magnetization and neutron diffrction study on HoMn6Sn6 topological Kagome metal. In another part, signatures of the correlated structural disorder will be demonstrated by sin-gle crystal X-ray, and neutron diffraction study on distorted topological metal NdMn6Sn6 from the same 166 kagome family.

Speaker: PIKESH PAL (ülich Centre for Neutron Science JCNS at MLZ)

152 P-068: REFSANS: The horizontal time-of-flight reflectometer with GISANS option at the Heinz Maier-Leibnitz Zentrum

REFSANS is the horizontal TOF reflectometer with GISANS Option at the MLZ, designed to enable reflectometry and GISANS studies of any interface, as well as to give simultaneous access to a range of Qz values, which is especially useful to study air-liquid interfaces or kinetic phenomena.
Wavelength resolution may be tuned from 0.2 % up to 10%. The optical system allows to independently control the horizontal and vertical beam divergence, in dependence on the sample characteristics. The investigation of kinetic processes is possible thanks to the possibility to embrace a Qz-range with a single instrumental setting. Time resolution can be pushed down to 30 s with data recorded in list-mode: in this way it is possible to perform different time re-binnings for tuning the resolution/intensity trade-off after the experiment.
Taking advantage of the long reactor shutdown, extensive simulations has been performed to find solutions that could increase the performance of the instrument and the flux at the sample position. It has been verified that with a modified design of the instrument geometry and with a new geometry of the radial collimators it would be possible to increase the flux on the sample up to a factor 4.3 for NR as well as 4.5 for GISANS measurements, for sample of typical sizes (50·80 mm2). The new design makes also possible to investigate small interfaces (30·30 mm2) with a gain factor of 3.2 in intensity, opening new options for the experimental analysis of interfaces.

Speaker: Gaetano Mangiapia

153 P-092: Relocation of the cold triple axis spectrometer FLEXX to MLZ, Munich: Larmor diffraction and inelastic scattering

The cold triple-axis spectrometer (TAS) FLEXX at HZB is a well-designed and upgraded instrument [1-4]. There was a strong wish that this excellent instrument should be preserved for the community. One attractive gap in the present instrumentation suite of MLZ, is the Larmor-diffraction technique [5-6] (LD) and, as a natural extension, cold neutron resonant spin echo (NRSE). TAS comes at no extra cost, as it is the main backbone of such an instrument.
The instrument will be placed on a cold neutron guide. Further, new developments are under way to allow for application of magnetic fields at the sample, hitherto not possible [7-9]. This opens up new vistas in the exploration of materials. A last attractive option is the possibility to combine high magnetic fields together with cold TAS.

[1] M. Skoulatos et al., NIMA 647, 100 (2011).
[2] M.D. Le et al., Nucl. Instr. Meth. Phys. Res. A 729, 220 (2013).
[3] F. Groitl et al., Rev. Sci. Instrum. 86 025110 (2015).
[4] K. Habicht et al., EPJ Web of Conferences 83, 03007 (2015).
[5] M.T. Rekveldt, Jour. Appl. Phys. 84, 31 (1998).
[6] M.T. Rekveldt et al., Europhys. Lett. 54, 342 (2001).
[7] Neutron Spin Echo - Proceedings of a Laue-Langevin Institut Workshop, Grenoble, Springer- Verlag, Ed: F. Mezei (1980).
[8] M.T Rekveldt et al., Jour. Appl. Cryst. 47, 436 (2014).
[9] K. Habicht, “Neutron-Resonance Spin-Echo Spectroscopy: A High Resolution Look at Dispersive Excitations”, Habilitation, University of Potsdam (2016).

Speaker: Markos Skoulatos (TUM)

154 P-104: Renewal concept TOFTOF

As a cold time-of-flight spectrometer, TOFTOF’s impacts are felt across scientific areas including: biophysics, materials science; fundamental hard and soft condensed matter physics, chemistry and biology. The impact is not only as a stand alone instrument but also as part of the suite of neutron spectrometers (e.g. SPHERES and J-NSE PHOENIX) addressing scientific questions which require perspectives on molecular dynamics over broad overlapping timescales and length-scales. The upgrade addresses both the competitiveness both of the instrument but also more broadly the competitiveness of the MLZ around existing scientific areas, and the aspirational grand challenges for the MLZ and its user community. Specifically we seek to enhance the sample area, angular resolution and number of neutrons analyzed by increasing the flux at the sample, decreasing background signal and increasing solid angle coverage and angular resolution. This enhanced instrument capability will be complemented by a number of new sample environment capabilities under development leading to new applications for neutron spectroscopy.

Speaker: Marcell Wolf (TUM)

155 P-042: RESEDA@BOA - or how to successfully build a MIEZE setup in 5 days

RESEDA is the only operational longitudinal MIEZE spectrometer world wide. Therefore, it is impossible to perform out-of-the-box experiments on the subject of entangled neutron beams at any other neutron scattering facility. We tackled this challenge by setting up the RESEDA MIEZE arm at the BOA test beamline located at the Paul Scherrer Institut in Switzerland.
This endeavour was a full success, as we managed to install the entire MIEZE components with the necessary hardware and software interfaces in under 5 days. Measurements of the spin-energy-entanglement of the neutron states were subsequently performed.

Speaker: Johanna K. Jochum

156 P-030: Residual stresses in bronze matrix composite surface deposits after laser melting injection

Wear causes a loss of 2% to 7% of the gross national product in industrialized countries. Therefore, developing wear-resistant coatings and optimizing their manufacturing processes are essential. A novel metal matrix composite (MMC) coating has been developed via laser melting injection (LMI) technique over the last few years, which consists of a bronze matrix and tungsten fused carbides. Tribological tests have shown that this MMC coating has the potential to reduce wear by ~80%.
However, macro and micro residual stresses exist in the MMC coatings, which significantly affect the performance of the MMC coatings, such as causing dimensional distortion, reducing the fatigue strength and service life. Therefore, it is critical to characterize the residual stresses in the MMC coatings.
In this research, the residual stresses in the LMI bronze matrix composite surface deposits were measured via neutron diffraction experiments. The residual stresses along the depth direction from the surface of the deposit to the center of the sample were determined nondestructively due to the large penetration depth of neutrons. Based on this result, a thermo-mechanical finite element model was developed to describe the measured stress distribution. The combined experiment and simulation study provides detailed insight into the residual stress state in the LMI MMC coatings and is helpful in optimizing the laser processing and tailoring the residual stress.

Speaker: Michael Hofmann

157 P-110: Revealing the effect of solvent additive selectivity on formation kinetics in slot-die coated organic solar cells at ambient conditions

Solvent additives have received tremendous attention in organic solar cells as an effective way to optimize morphology and phase separation. However, most research primarily focuses on solvent additives with superior solvation for non-fullerene acceptors (NFA) over polymer donors, such as the 1-chloronaphthalen (1-CN), 1, 8-diiodooctane (1,8-DIO). Few researches are related to solvent additives characterized by better solubility for polymer donors than NFA. Furthermore, the impact of solvent additives is mainly investigated through spin coating rather than slot-die coating, which exhibits distinct kinetics in film formation. Hence, the influence of solvent additive selectivity on the kinetics of active layer formation in the printed active layer remains unknown. In this study, we use PBDB-T-2F as the donor and BTP-4F as the acceptor and introduce two distinct solvent additives—one with superior solubility for PBDB-T-2F compared to BTP-4F, and the other with inferior solubility for PBDB-T-2F. The drying process of the slot-die coated active layer with different solvent additives will be studied by in situ UV-vis absorption spectra and in situ Grazing Incidence Wide Angle X-Ray Scattering (GIWAXS).

Speaker: Jinsheng Zhang (TUM)

158 P-094: Sample Environment @FRM2: latest developments and new equipment

In addition to state-of-the-art neutron scattering instrumentation, sample environment is another important pillar to attract the user community.

On this occasion, new devices and developments will be presented such as closed cycle refrigerators with temperature extension up to 1.5K, development of high-pressure equipment for SANS, progress in automatic sample exchange systems and the new Adiabatic Demagnetization Refrigerator (ADRs).

Speaker: Manuel Suarez Anzorena (Forschungs-Neutronenquelle Heinz Maier-Leibnitz (FRM II))

159 P-071: SANS-1MAX: Massive Q-Range Upgrade

The SANS-1 MAX proposal aims both at extending the dynamical Q-range and increasing the maximal momentum transfer Q. The SANS-1 MAX proposal consists of two independent two subprojects. (i) The replacement of the S-bender neutron guide, second selector and the upgrade of the TISANE chopper discs with an optimized version will shift the wavelength cut-off down to ~2.8 Å and allow for a drastically improved, flexible wavelegth resolution. (ii) The installation of a second, high-Q detector bank at short detector distances on a second, independent detector carriage will largely improve the dynamic range.

Both upgrades will enable the access to new fields of research, particularly for modern engineering materials and energy materials. The increased dynamical Q-range is particularly beneficial for the growing demand of in-situ measurements of irreversible processes, e.g., precipitation growth, quenching of alloys, rapid heating and cooling processes and the mimicking of metal process chain. Accessing larger Q allows measuring even smaller correlations of a few atoms to study the early growth of precipitates. A maximum momentum transfer of 2.2 Å^-1 of the SANS-1MAX proposal will finally allow covering the first Bragg peaks of typical energy materials. This option will enable coherent investigations of early stage precipitation covering the SANS and diffraction region in a single measurement.SANS-1MAX will also tremendously increase the overall efficiency of SANS-1.

Speaker: Sebastian Muehlbauer

160 P-109: SECoP: The Sample Environment Communication Protocol

The integration of sample environment (SE) equipment in a beam line experiment is a complex challenge both in the physical world and in the digital world. Different experiment control software offer different interfaces for the connection of SE equipment. Therefore, it is time-consuming to integrate new SE or to share SE equipment between facilities. To tackle this problem, the International Society for Sample Environment (ISSE) developed the Sample Environment Communication Protocol (SECoP) to standardize the communication between instrument control software and SE equipment (see [1] and references therein). SECoP offers, on the one hand, a generalized way to control SE equipment. On the other hand, SECoP holds the possibility to transport SE metadata in a well-defined way. Using SECoP as a common standard for controlling SE equipment and generating SE metadata will save resources and intrinsically give the opportunity to supply standardized and FAIR data compliant SE metadata. It will also supply a well-defined interface for user-provided SE equipment, for equipment shared by different research facilities and for industry. In this presentation we will give an overview of the present status of SECoP and the developments within the SECoP@HMC project supported by the Helmholtz Metadata Collaboration. [1] K. Kiefer, et al. (2020). An introduction to SECoP – the sample environment communication protocol. Journal of Neutron Research, 21(3-4), pp.181–195

Speaker: Alexander Zaft (Forschungszentrum Jülich)

161 P-111: Self-assembly of thermo- and photo-responsive diblock copolymers

Stimuli-responsive diblock copolymers (DBCPs) have gathered considerable interest for uptake, delivery and release processes due to their property tunability upon exposure to external stimuli, such as temperature and light. In this study, DBCPs comprising PNIPAM as the thermoresponsive block and azopyrazole (AzPy) functionalized PNDMAM as the photo-responsive block are expected to feature dual lower critical solution temperature (LCST) behavior with coil-to-globule transitions at the respective cloud points (CP). At this, the CP of the PNIPAM is expected to remain unchanged, while the other CP may be altered by exposure to UV light. This way, the system can be switched fully externally from unimers to micelles or inverse micelles and aggregates. Here, we present the temperature-dependent phase behavior of PNIPAM-b-P(NDMAM-co-AzPyNDMAM) with different degrees of polymerization and AzPy contents in different isomeric states of the latter. Dynamic light scattering (DLS) revealed that both BCPs exhibit a cloud point (CP2) and a subsequent clearing point (CP1) in both their trans- and cis-state. Furthermore, in the cis-state, the CPs are slightly shifted, while the aggregates are significantly larger than in the trans-state.

Speaker: Peiran Zhang (Technical University of Munich, Physics Department, Garching, Germany)

162 P-060: Silicon detector for neutron beta decay measurements with PERC

The PERC facility is currently under construction at the FRM II in Garching, Germany. It will serve as an intense and clean source of electrons and protons from neutron beta decay for precision studies. It aims to improve the measurements of the properties of weak interaction by one order of magnitude and to search for new physics via new effective couplings.
PERC's central component is a 12 m long superconducting magnet system that has been delivered. It hosts an 8 m long decay region in a uniform field. An additional high-field region selects the phase space of electrons and protons, which can reach the downstream detector to minimize systematic uncertainties.
The downstream detector and the two upstream backscattering detectors will initially be scintillation detectors with (silicon) photomultiplier readout. In a later upgrade, the downstream detector will be replaced by a pixelated silicon PIN-detector. This new detector is 2mm thick. The entrance window consists of a 100nm thin p+ doped layer with a 300nm thin aluminium grid on top and the readout side is 500nm of pixelated n+ doping.
The detector is scheduled to be delivered in the fourth quarter of 2023, and we are presenting the first results of its characterization.

Speaker: Manuel Lebert (Technical University Munich)

163 P-076: Similar time-dependent morphology evolution of titania films from different precursors

Mesoporous transition metal oxide has attracted a lot of interest due to its excellent properties. Block copolymers with sol-gel is one of the popular approaches to fabricate mesoporous transition metal oxides. In this work, titania thin films are synthesized with the sol-gel method templated by a diblock copolymer. A similar morphology transition, from worm-shaped mesopores to ordered spherical mesopores, was observed with increasing sol-gel reaction time for different titanium precursors. The surface morphologies of films are probed via scanning electron microscopy and GISAXS.

Speaker: Guangjiu Pan (Technical University of Munich)

164 P-100: Six-axis robotic arm driver: Zoning out with Frappy and NICOS

The Automatic Laue Sample Aligner (ALSA) uses a robotic arm (Mecademic Meca500 [1]), computer vision [2], and air suction to manipulate small crystal samples.
While controlling the robot arm, operating with the absolute reference frame of the robot would be quite confusing for the end user. Therefore, taking inspiration from Entangle [3] implementation, we have written a control driver using Frappy framework to communicate via SeCOP [4]. Our approach allows us to define zones (such as crystal pickup area or beam area), providing a local reference frame that is much easier to operate and perform linear movement.
The driver handles the movement between zones and the translation of the local coordinates seamlessly.
A NICOS integration is used to command the robotic arm to move between the defined zones, move within a zone, or read the current position. This is coupled with computer vision that detects the positions and shapes of the supplied crystal samples.
The driver is written in a general way as a reusable project that can be easily adapted for another application.

[1] https://www.mecademic.com/meca500-industrial-robot-arm/
[2] "Computer vision integration into the NICOS", poster of Tomáš Červeň, MLZ users 2023
[3] G. Brandl, https://forge.frm2.tum.de/review/c/frm2/tango/entangle/+/21507
[4] Kiefer, Klaus, et al. Journal of Neutron Research 21.3-4 (2019): 181-195.

Speaker: Stepan Venclik (Charles University)

165 P-027: Slot-die coated cellulose colloid layer

Slot-die coated cellulose nanofibrils CNF layers are compact, homogenous, and have a low roughness. These properties give them specific imbibition properties for different colloids. We studied the coating of the novel slot-die coated CNF layer in real-time using grazing incidence small-angle X-ray scattering. We compare the imbibition properties of water and colloidal inks of slot die-coated CNF layer with well-known spray-coated CNF layer. To study the imbibition properties, we apply poly-butylmethacrylate (PBMA) and polysobrerolmethacrylate based inks in an aqueous solution. The depositions are observed via GISAXS. In addition, the imbibition properties of the CNF systems during annealing are quantified. Our results show that the structure and morphology of the hybrid CNF-colloid layers will change when the glass transition temperature of the colloids is exceeded.
Spectroscopic ellipsometry shows that the small colloids can be imbibed into the cellulose nanofibrils (CNF) layer and change the refractive index for the pure CNF layer. A gradient in the refractive index correlates to the imbibition depth of the colloids into the CNF layer of the small colloidal system. The colloids only form a top layer on CNF without a gradient layer. After the evaporation of the water, the voids are filled with colloids. During the annealing, we observed shape changes of the colloids. These results can be used for a better and more stable coating of nanoparticles on porous materials.

Speaker: Constantin Harder (DESY)

166 P-079: Status of the datacatalogue at MLZ

Within the DAPHNE4NFDI project the MLZ is enganged in establishing a datacalougue to foster FAIR access to the data produced at the MLZ.

We will give an overview over the technical aspects of the implementation of such a catalogue at MLZ.

Speaker: Dr Bjoern Pedersen (Forschungs-Neutronenquelle Heinz Maier-Leibnitz(FRM II), TU München)

167 P-050: Status Report of the MEPHISTO Beamline

The author will present the actual status of the work at the MEPHISTO beamline. The installation of the neutron guide shielding in the reactor building is progressing and the cooling plant await its compressor housing construction.

Speaker: Jens Klenke (FRM II)

168 P-106: Structural study of polyoxazoline-grafted PMMA amphiphilic copolymers

Poly(2-oxazoline)s are biocompatible polymers featuring high copolymerization versatility and low in-vivo immunogenicity [1]. Thus, the system has potential in biomedical applications. While linear poly(2-oxazoline) homo- and block copolymers have been amply studied, studies on molecular brushes from poly(2-oxazoline)s are still scarce [2, 3]. In the present study, we investigate molecular brushes, in which poly(2-oxazoline)s with methyl or n-butyl side groups (namely PMeOx, hydrophilic and PBuOx, hydrophobic) were densely grafted onto a polymethyl methacrylate (PMMA) backbone. The backbone is either linear or has a star-shaped multi-arm configuration. The grafted chains are PBuOx-co-PMeOx diblock copolymer with the PBuOx ends connected to the backbone. The star-shaped brushes were investigated in dilute aqueous solution using dynamic light scattering (DLS) and synchrotron small-angle X-ray scattering (SAXS). This way, the size and shape of the molecules was determined. Our preliminary results show that an increased backbone-to-sidechain length ratio will lead to elongated brush shapes.

References:
[1] T. X. Viegas, M. D. Bentley et al., Bioconjugate Chem., 2011, 22, 976.
[2] J.-J. Kang, C. M. Papadakis et al., Colloid Polym. Sci., 2021, 299, 193.
[3] J.-J. Kang, C. M. Papadakis et al., Langmuir, 2022, 38, 5226.

Speaker: Wenqi Xu (Technical University of Munich, TUM School of Natural Sciences, Soft Matter Physics Group)

169 P-055: Structure and dynamics in functional polymer films

Hydrogel films made from responsive polymers are able to switch between a swollen (extended polymer chains) and a contracted film state (coiled polymer chains) in response to slight changes in their surroundings. In recent studies, we demonstrated the versatility of a multi-responsive diblock copolymer, containing a zwitterionic poly(sulfobetaine) and a nonionic poly(N-isopropyl acrylamide) block, in thin-film geometry. With neutron scattering techniques such as time-of-flight neutron reflectometry and grazing-incidence small-angle neutron scattering (ToF-NR, ToF-GISANS), we identified discrete thin-film states, regarding their thickness, solvent content, and morphology, which can be precisely tuned upon changing external stimuli such as temperature, relative humidity, and the composition of the surrounding solvent vapor.
In future studies, we aim to use responsive biomaterials such as cellulose, as functional materials, due to their sustainability, biodegradability, high abundance, and low cost. Recent studies focused on the structural properties of cellulose nanofibrils during dynamic processes such as swelling and drying. For a fundamental understanding of their functionality, both the structure and the internal dynamics of the moieties are important. Therefore, these future studies will have a strong focus on the investigation of dynamical parameters using neutron techniques e.g., quasi-elastic neutron scattering (QENS) or neutron backscattering spectroscopy.

Speaker: Dr Lucas Kreuzer (MLZ (FRM II, TUM))

170 P-062: Template-Induced Growth of Sputter-Deposited Gold Nanoparticles on Ordered Porous TiO2 Thin Films for Surface-Enhanced Raman Scattering Sensors

Ordered porous gold/titanium dioxide (Au/TiO2) hybrid nanostructured films are specifically interesting in large-scale applications using localized surface plasmon resonances (LSPRs) and surface-enhanced Raman scattering (SERS). In this work, we investigate the optical response of sputter-deposited Au/TiO2 nanohybrid thin films with a focus on the plasmonic response and application as molecular sensors. To elucidate the origin of this behavior, we apply in situ grazing-incidence small-angle X-ray scattering (GISAXS) to investigate the growth kinetics of Au on a TiO2 template during sputter deposition. Based on time-resolved GISAXS, the growth characteristics of sputter-deposited Au on TiO2 template with a final effective Au layer thickness around the percolation threshold is described with the well-known four-stage model of nucleation and cluster formation, diffusion-mediated growth, adsorption-mediated growth and grain growth. The Raman intensity of deposited molecules, probed with rhodamine 6G (R6G), depends on the deposited gold thickness. It shows its maximum at the effective Au thickness (δAu) of 3.4 nm. The maximum in SERS intensity is corroborated by the existence and optimal size of hot spots in the narrow space occurring between the sputter-deposited Au clusters, when staying below the percolation threshold.

Speaker: Suzhe Liang (Physical Department, TUM)

171 P-090: The cold neutron imaging beam line ANTARES

The cold neutron imaging beam line ANTARES at FRM II is a state of the art facility, which combines excellent beam properties with highly flexible experimental conditions. User experiments can be performed with complex sample environment like croystats, furnaces or tensile rigs.
In this poster, we give an overview of the beam line layout and possible options of the beam line. Moreover, we will show examples of selected experiments performed at ANTARES to demonstrate the potential of the beam line.

Speaker: Michael Schulz

172 P-078: The Data Evaluation Group DEVA at MLZ

The Data Evaluation Group DEVA at MLZ is a team of scientists with many years of experience in selected neutron and X-ray methods. DEVA was established in 2022 with the goal of guiding and actively supporting the user community, with a focus on new users. This includes data analysis and data reduction, assistance in extracting further knowledge from the acquired data, and support in the preparation of publications. DEVA helps to ensure that valuable data do not remain unprocessed and unpublished. Another successful activity of the group is the organization of workshops for training in complex analysis software. So far, the group's services have been very well received, the workshops have usually been fully booked, and a substantial part of the previously deferred data could be analyzed and published. We provide an overview of the group's capabilities, summarize its recent activities, and present an outline of future developments.

Speaker: Dr Neelima Paul (Technical University of Munich, Heinz Maier-Leibnitz Zentrum (MLZ))

173 P-103: The direct geometry cold chopper spectrometer TOFTOF

TOFTOF is a direct geometry disc-chopper time-of-flight spectrometer. TOFTOF represents a versatile instrument combining high energy resolution, high neutron flux (also at short wavelengths), and an excellent signal-to-background ratio. It is perfectly suited for inelastic and quasielastic neutron scattering and scientific topics include e.g.:
• Diffusion in liquid metals and alloys
• Hydrogen dynamics in soft matter systems such as molecular liquids, polymer melts or colloids
• Molecular magnetism, quantum criticality in heavy fermion compounds, low energy excitations in multiferroic materials and novel magnetic phases
• Dynamic properties of energy storage materials, such as solid state hydrogen storage materials, electrolytes, or gas storage materials
• Energy-resolved quasi-elastic neutron scattering on proteins, vesicles, and biological materials
• Kinetic studies of hydrogen binding
• Aging effects in disordered media and low frequency dynamics in glasses
• Biological activity and functionality of proteins and cells under pressure

Speaker: Marcell Wolf (TUM)

174 P-004: The JCNS polarized 3He group

Our group operates and/or develops in-situ 3He polarizers/analyzers for the following instruments: MARIA, KWS1, KWS2, TOPAS, POLI (2x), DREAM (ESS), and TREX (ESS). We are also active in developing polarized neutron beam components and testing. We will present a summary of the status and performance of the various devices.

Speakers: Earl Babcock, zahir salhi (JCNS)

175 P-074: The Macromolecular Neutron Single Crystal Diffractometer BIODIFF for Proteins at the Heinz Maier-Leibnitz Zentrum MLZ

Neutron single crystal diffraction provides an experimental method for the direct location of hydrogen and deuterium atoms in biological macromolecules. At the FRM II neutron source the neutron single crystal diffractometer BIODIFF, a joint project of the Forschungszentrum Jülich and the FRM II, is mainly dedicated to the structure determination of enzymes. Typical scientific questions address the determination of protonation states of amino acid side chains in the active center, the orientation of individual water molecules essential for the catalytic mechanism and the characterization of the hydrogen bonding network between the enzyme active center and an inhibitor or substrate. This knowledge is often crucial towards understanding the specific function and behavior of an enzyme. BIODIFF is designed as a monochromatic diffractometer and is able to operate in the wavelength range of 2.4 Å to about 5.6 Å. This allows to adapt the wavelength to the size of the unit cell of the sample crystal. Data collection at cryogenic temperatures is possible, allowing studies of cryo-trapped enzymatic intermediates. Recently a hexapod has been installed at BIODIFF which allows an easy online collimator alignment. Some recent examples will be presented to illustrate the potential of neutron macromolecular crystallography. In addition, a potential detector upgrade for BIODIFF will be presented, which will expand the maximum unit cell limits.

Speaker: Dr Andreas Ostermann (Heinz Maier-Leibnitz Zentrum (MLZ), Technische Universität München)

176 P-098: The Stress and TExture CAlculator software tool

The “Stress and TExture CAlculator” (Steca) is a data reduction software tool. It is used to support the analysis of the data from x-ray material diffractometers and neutron strain scanner STRESS-SPEC.

In particular, peak positions, widths and intensities are extracted from the 2D detector data of the instruments. The extracted data can be saved within a Steca project file or exported into different formats for external use.

The software is developed and maintained by the Scientific Computing Group of the JCNS in Garching in close contact with the scientific staff of the instruments. Steca is open-source software written in C++. Utilizing the Qt framework, Steca is available for both Windows and Linux operating systems.

Speaker: Christian Trageser (Forschungszentrum Jülich)

177 P-034: Thermal and structural stability of lithiated graphite battery anodes

High-performance graphite is nowadays on of the most used anode materials in state-of-the-art Li-ion batteries. However, understanding the structural stability of lithiated graphites (Li$_{x}$C$_{6}$ with x<1) and its phase diagram remains limited and complex. In literature, the thermal-resolved phase stability of lithiated graphites is studied poorly and the results are often controversial [1, 2]. Thus, this study focuses on lithiated graphites at elevated temperatures, revealing structural changes, the loss of lithium, and the emergence of novel phases as LiF and Li$_{2}$O which are strongly linked to the degradation of the solid electrolyte interface (SEI), a critical factor in the performance of Li-ion batteries. The studies deepen the understanding of the behavior of lithiated graphite at high temperatures, which is particularly important with respect to fast charging applications and the degradation mechanisms of Li-ion batteries, which are crucial for modern energy storage systems.

[1] A. Senyshyn, M. J. Mühlbauer, O. Dolotko, and H. Ehrenberg, J. Power Sources 282, 235-240 (2015). (DOI 10.1016/j.jpowsour.2015.02.008.)
[2] V. Baran, O. Dolotko, M. J. Mühlbauer, A. Senyshyn, and H. Ehrenberg, J. Electrochem. Soc. 165, 1975-1982 (2018). (DOI 10.1149/2.1441809jes)

Speaker: Tobias Hölderle

178 P-006: Towards Polarized Backscattering with High resolution

Polarization analysis provides profound additions in knowledge for the field of soft condensed matter research. The ability to study dynamics of incoherent and coherent scattering contributions separately gives unique information on the cooperative vs local dynamics of a system. The JCNS is interested in exploring new instrumentation ideas as a polarization analysis upgrade to our SPHERES backscattering instrument and new ideas for the proposed High-brilliance Source (HBS). In particular we will discuss the current concepts on ways of achieving polarization analysis for the high resolution regime, i.e $\Delta$E<1μ eV on a traditional backscattering instrument such as SPHERES at MLZ and point out the differing instrumental challenges and application compared to near-backscattering type spectrometers being proposed for pulsed sources.

Speaker: Earl Babcock

179 P-029: Tuning the Morphology of Biohybrid β-lg:titania Films with pH for Water-Based and Nanostructured Titania

Metal oxide interfaces, especially nanostructured titania, play a key role in various energy applications. Achieving controlled morphology at different scales is critical for optimal performance. Nanostructured titania with a high surface-to-volume ratio improves device efficiency. Industrial methods such as spray coating are effective, but often involve unsustainable organic solvents. To address this, water-soluble biopolymers, specifically bovine whey protein ß-lactoglobulin (ß-lg), are being explored as sustainable alternatives. ß-lg acts as a template in water-based titania synthesis, forming different aggregates depending on the pH. Biohybrid films are fabricated using spray deposition with different pH solutions. Investigative techniques provide insight into how pH affects film morphology, including grazing-incidence small-angle neutron and X-ray scattering (GISANS/GISAXS) and real-space imaging. This research aims to develop environmentally friendly, scalable methods for titania-based materials in energy applications, thereby reducing the environmental impact associated with conventional synthesis approaches.

Speaker: Julian Heger (TUM School of Natural Sciences, Chair for Functional Materials)

180 P-005: Using polarized $^3$He to probe 3-body interactions

Low n nuclei with spin are important for understanding spin-dependent portions of 3-body interactions. These three body forces account for about 5% of the nuclear biding energy, but are poorly experimentally constrained. The binding energy of $^4$He for example can only be predicted to about 1% with current theoretical calculations. The polarized n-$^3$He system can be used to probe these interactions with precision measurements of the associated cross sections. We have been following a two tiered path. First is to improve the accuracy of the n-$^3$He incoherent scattering cross section $b_i$ though neutron spin-echo measutments, and second is to attempt to measure explicitly the polarized n-$^3$He absorption cross section $\sigma_p$ (or absolute $^3$He polarimetry) which is needed for an absolute determination of b_i. Recent experiments to measure $b_i$ were performed at the SNS-NSE with data analysis ongoing, and measurements of $\sigma_p$ are planned for the spring at ISIS.

Speaker: Earl Babcock

181 P-066: Visualizing the propagation of the neutron spin state at the MIEZE spectrometer RESEDA

Modulation of intensity with zero effort (MIEZE) is a neutron spectroscopy technique with high energy resolution, closely related to the established neutron spin echo (NSE) method. The essential feature of MIEZE is an intensity modulated neutron beam with a focal point (echo point) several meters downstream the sample.
Successful employment of the MIEZE technique requires careful preparation of the neutron spin states prior to scattering in the sample. Two radio-frequency spin flippers (RF-flipper) first split the neutron spin states energetically and recombine them at the detector position if tuned correctly to the so called MIEZE condition. While this phenomenon is precisely captured by analytical classical vector or quantum mechanical spinor models, they are based on simplifying assumptions and the results are hardly intuitive. This is where modern computational tools can improve our understanding on both fronts. First, it allows the incorporation of real world instrument conditions. Second, the spin states can be visually captured at every point in time.
Here, we present the first steps in using the Quantum Toolbox in Python (QuTiP) to simulate the neutron spin states as they propagate along the RESEDA beamline. Every step along the different neutron precession devices, the neutron spin gathers a phase, which we will visualize in short video clips presented on a tablet next to the poster in the attempt to further the understanding of MIEZE in the user community.

Speaker: Mr Roman Lvovich (RESEDA FRM II)