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The structural behavior of battery materials during cycling and fatigue must be studied under real operation conditions. This contribution reviews the capabilities and challenges of in operando measurements using X-rays, synchrotron or neutron radiation with a focus on diffraction and spectroscopy. Selected examples are discusses for Li-ion batteries and for electrochemical energy storage “beyond lithium”, like Na- and Mg-batteries.
I will present crystallographic snapshots of the human enzyme orotidine-5-monophosphate decarboxylase in complex with the genuine substrate, substrate analogs, transition state analogs and product - all at true atomic resolution. These snapshots of catalysis defy the proposed mechanism of ground-state destabilization by revealing that the substrate carboxylate is protonated and forms a favorable low-barrier hydrogen bond with a negatively charged amino acid.
PlaB is a secreted phospholipase of Legionella pneumophila, the causative agent of Legionnaires' Disease. It is an unusual enzyme that looses activity at higher concentrations due to tetramer formation.
Here, we show the crystal structure of PlaB in its inactive tetrameric form. We find that the tetramer is stabilized by NAD(H), a central metabolite only found within the cell. This ligand-mediated oligomerization may hence establish a self-protection mechanism.
The DYW domain, an enzyme for plant RNA editing: Pentatricopeptide repeat (PPR) proteins with a C-terminal DYW domain are responsible for C to U RNA editing in plants. We show that the DYW domain harbors the cytidine deaminase activity by functional data in vitro and structural similarity to distinctly related known cytidine deaminases. A DYW-specific domain regulates the active site sterically via a large-scale conformational change and mechanistically via the Zn-coordination geometry.
The innate immune sensor 2’-5’-oligoadenylate synthetase (OAS) is among the most promising targets for the development of new antivirals. Here we report the results of kinetic crystallography, mutagenesis, and computational chemistry studies of the OAS1 product release mechanism. These investigations provide new insights into the rate-limiting steps of innate immune signaling, which can help develop allosteric activity modulators of OAS for therapeutic application.
O2 activation is central elementary step in many biological reactions. The formylglycine generating enzyme (FGE) is a mononuclear copper enzyme that appears to follow an unusual strategy for O2 activation. In this presentation I will summarize our past and present efforts to visualize individual states of the enzyme on its path from the resting state to the reactive Michaelis Menten complex and beyond.
Kesterite-type based thin film solar cell technologies are mainly based on polycrystalline absorber layers. A promising low cost alternative technology uses Cu$_{2}$ZnSn(S,Se)$_{4}$ (CZTSSe) monograins (single crystals of 50-100 μm size) fixed in a polymer matrix to form a flexible solar cell.
In this study we tackle the influence of grinding the monograins on the stoichiometry deviation, the Cu/Zn disorder as well as intrinsic point defects and optoelectronic properties of CZTSSe monograins.
Alternative photovoltaic absorbers often suffer from scarce and/or toxic components. Herein, we look at the model system Zn$_{1+x}$Ge$_{1-x}$(O$_x$N$_{1-x}$)$_2$, which we studied in detail using Neutron diffraction, chemical analyses and UV-VIS measurements. We show that two independent ways of cation disorder exist: one related to the chemical composition and one based on antisite defects. Despite being independent, both disorder types affect the optical bandgap energies similarly.
Lead halide perovskites have shown excellent optoelectronic properties, yet they are sensitive and unstable under humidity. Herein, we did an in-situ humidity X-ray scattering study to unravel the intermediate and final degradation phases of cesium-formamindinium lead halide perovskites. It was observed that the origins of phase transitions in lead halide perovskites go beyond humidity: the humidity carrier gas, stoichiometry, and composition play an important role in the degradation kinetics.
Compound semiconductors with a high absorption coefficient are the most advanced and most efficient absorber materials in thin film photovoltaic (PV) technologies. Highly efficient devices are based on absorber layers from ternary or quaternary chalcogenides or hybrid halide perovskites. The crystal structures of these materials are based on corner sharing building blocks: tetrahedra (chalcogenides) and octahedra (halides). Their sucess as PV material lies in the overall structural flexibility.
Ikaite (CaCO3 x 6H2O) is a widespread mineral in cold regions of Earth. Furthermore, it plays a key role as a precursor of more stable calcium carbonates. However, the formation and transformation conditions of ikaite, especially for the heterogeneous case, are not well constrained. Using Cryo-Mixed-Batch-Reactor experiments and in-situ flow-through Cryo-Atomic-Force-Microscopy (CAFM), we investigated the effect of mineral substrates on the nucleation of ikaite and its subsequent disintegration.
This work compares dental enamel of 18 different species from the taxa of rodents (Rodentia), lagomorphs (Lagomorpha) and insectivores (Eulipotyphla). The enamel structure was analysed by scanning electron microscopy (SEM). To analyse the chemical composition of the dental enamel, energy-dispersive X-ray spectroscopy (EDS) was used together with X-ray powder diffraction for a structural characterization of the tooth mineral.
We determined the crystallographic and microstructure properties of the biocalcite of two species of regular sea urchins by electron backscatter microdiffraction (EBSD) and laboratory X-ray diffraction. The spines are essentially single crystals despite their segmented and/or stereom-like structure of hollow space between calcite walls. The body test plates consist up up to 1mm sized single-crystalline stereom blocks, separated by small-angle boundaries.
To understand the influence of bacterial metabolic activity at calcite crystallization, we synthesized hydrogel-calcite composite aggregates with B. subtilis. Our results show that living microorganisms strongly influence the mineral microstructure and texture. This characteristic indicates that bacterial EPS can be developed as a further tool (a biomarker) for the recognition and identification of bacterially mediated calcification in present environments as well as in the geological record.
We investigated the sub-micrometer to nanometer scale organization of calcite and aragonite biocrystals with EBSD, FE-SEM and STEM. We highlight the very specific microstructural nature of foraminiferal calcite and aragonite, in particular, the extensive {001} twinning of shell carbonate, describe a new microstructure for the twinned crystals and show that species that developed perfect/near-perfect spherical chamber/shell morphologies have their shell calcite almost fully twinned.
Theory and Education
The automatic identification of these Debye–Scherrer rings after data processing and merging is difficult, hence we explore two automatic approaches: statistical testing and machine learning. Combining the strengths of both methods, the new assessment shows quantitatively, at the potential ice ring ranges, how severe the intensity observations are affected by the presence of ice rings.
The aim of this contribution is to present briefly the new Teaching Edition of International Tables for Crystallography (ITC) that provides an introduction to the symmetry information found in Volume A, Volume A1 and Volume E of ITC, to magnetic space groups and to the Symmetry Database that forms part of Online Edition of ITC.
The crystal structure of the elemental boron polymorph $\beta$-rhomohedral boron has been investigated by means of high-resolution X-ray diffraction using synchrotron radiation and samples of high purity. We will discuss the peculiar chemical bonding in this complex boron polymorph based on a multipolar refinement and the resulting electron density.
DISEMM is a software tool to analyse neutron or X-ray diffraction data collected under mechanical load combining the determination of single-crystal elastic constants and the methods of elasto-plastic self-consistent modelling in one package. The software is available for download from https://github.com/Gipfelgrab/DISEMM
We use various computational methods (DFT, molecular docking, interaction analysis) to characterize and quantify the host-guest interactions in metal-organic and covalent organic frameworks. We will show results for several different application cases and discuss their relation to experimental findings.
In macromolecular crystallography, electron density maps are used to build and validate models. In particular, OMIT maps are commonly used to verify ligands. If the ligand is present, it is expected that the electron density of the ligand will appear as positive features in the OMIT map. However, if the density arising from the omitted atoms is weak, it may be obscured by bulk solvent. The polder map approach prevents bulk solvent from entering OMIT regions, leading to clearer map features.
The synthetic $^{4}$L-(Pb)$_{4}$(Cu,Sb)$_{8}$(Pb,Sb)$_{8}$Se$_{24}$ crystallizes in the superspace group Cmc2$_{1}$(α00)000 with a = 4.165 Å, b = 14.085 Å, c = 19.82 Å and the modulation vector q = 0.6882(3) a*. The mixed Pb/Sb sites are coordinated octahedrally by the Se atoms, almost every third Pb/Sb position is replaced by Cu that prefers a tetrahedral coordination of Se atoms. This phenomenon can be described by a combination of a positional and occupational modulation.
LibH4 shows strong diffuse scattering in layers normal to c* at integer l, predominantly at odd l. The diffuse scattering within the layers is circular around the Bragg reflections and stronger close to the reciprocal origin. This observation tits to columnar defects with a negative correlation in the a-b-plane and preserved correlation along c. The 3D-DELTA-PDF shows an intricate pattern of positive and negative peaks, which were interpreted with by manual Patterson search.
The presentation reports on our results of the inclusion of anomalous dispersion refinement into crystal structure determinations. Synchrotron experiments were carried out at different energies around the K-edge of Molybdenum. A very good correlation between the absorption spectrum of a given element and the refined dispersion values is achieved. The structure model remains unchanged before, after and even at the absorption edge.
SC-XRD solutions for challenging applications like MOFs/COFs rely heavily on the Xray source brightness for fast and precise data collection. Traditional Xray tubes are limited in brightness by when the e-beam power density melts the anode. This limit is overcome by the liquid-metal-jet anode technology that enables 10x more photons on the sample compared to solid tubes. This contribution reviews the evolvement of the MetalJet technology and will show some recent MOF/COF user examples.
The interface for refinement using Non-spherical Atoms in Olex2 (NoSpherA2) is expanded by various features to match requirements by different classes of materials and gives rise to new questions, for example, the treatment of anomalous dispersion, modelling of environments and description of heavy elements.
A common approach to deal with the unknown surface emissivity is to measure the thermal emission at multiple wavelengths – an approach called multi-wavelength pyrometry. Our new pyrometer uses 8 wavelengths from 600 to 1500 nm and different types of detectors, such as photodiodes and Multi Pixel Photon Counters (MPPC). This allows one to measure the temperature in a broad temperature range up to a few thousand Kelvins with high temporal resolution up to nanoseconds.
Here we report the application of energy-filtered electron radial distribution function (eRDF) analysis, combined with transmission electron microscopy imaging and X-ray powder diffraction, for elucidating the crystal structure and describing local order in carbon nitride powders with different degrees of crystallinity: (1) sodium polyheptazine imide (Na-PHI) and (2) amorphous CN covalent network (a-CN).
Ultrasmall metallic nanoparticles (diameter 1 to 2 nm) are of interest in research as they can be functionalized and used in biomedical applications. One of the most prominent methods for analyzing ultrasmall nanoparticles is high-resolution transmission electron microscopy (HRTEM). To effectively use HRTEM for a large-scale analysis of ultrasmall nanoparticles, an automated image processing is generated.
Electron diffraction (3D ED), that is using both the continuous rotation method and software as we know from X-ray crystallography, is gaining a lot of attention in all fields of research from organic and inorganic molecules, over geological sciences, material sciences to energy-storage materials and many others.
Here we showcase results from case studies dealing with challenging organic compounds to demonstrate the benefits over TEM-based MicroED experiments.
The local structure and Temperature-dependent crystallisation behaviour of oxygen doped Li thiophosphates, synthesised with two different sets of starting materials were investigated and compared, using mainly powder x-ray diffraction (PXRD) and pair distribution function (PDF) analysis.
Subsequently, impedance measurements were carried out to derive links between local structure and ionic conductivities.
Zinc-based batteries have been a recurring theme throughout history, from Volta's pile, the Daniell and Leclanché elements to powering modern space vehicles. To date, no rechargeable all solid-state Zn-ion battery has been commercialized. Therefore, we intended to contribute to increasing the number of available Zn-ion conductors for such batteries. We used a stepwise algorithm (Voronoi partition, BVSE, and DFT) to identify compounds from the ICSD prone to Zn-ion conductivity.
In the current contribution an overview and application of non-destructive of selected diffraction-based tools for spatially-resolved studies of closed electrochemical systems (on example of cylinder-type Li-ion batteries) is reported. Experimental methods will cover various-type of spatially-resolved diffraction and diffraction based tomography appliying neutron scattering and high-energy photons. Example of studies on different scales will be presented in brief.
The impact of γ´ nanoscale exsolution particles on the superelastic response of theCo49Ni21Ga30 shape memory alloy under tensile load - an in situ study
Single-crystalline elastic constants in titanium alloys Ti-6Al-4V, Ti-3Al-8V-6Cr-4Zr-4Mo and Ti-6Al-2Sn-4Zr-6Mo have been determined using neutron and synchrotron diffraction on polycrystalline bulk samples under mechanical load. An approach to account for load partitioning between the phases has been applied in the analysis. By this means not only the apparent elastic constants of each phase in the alloys were obtained, but also load transfer corrected values according to the pure phases.
R-values represent the discrepancy between our macromolecular models and the measured X-ray data; they typically are around 20%, clearly showing that something is amiss; our current models of macromolecular crystal structures seem to be lacking. A better understanding of the shortcomings in our current models (and methods) could be an important factor to solving the most difficult structures and to improving all others to obtain more biological information. But what causes this difference?
Recently, it became possible to use CdTe Eiger detectors in macromolecular crystallography, enabling the use of high energy X-rays. Experiments at Diamond's beamline I24 could show that the theoretically predicted benefits of increased diffraction efficiency and photoelectron escape can indeed be exploited in the data collection of macromolecular crystals and data from huge protein complexes could be collected to unprecedented resolution at EMBL's beamline P14 at PETRA III.
Here, we describe the application of Spatially Resolved Anomalous Dispersion (SpReAD) refinement as a method to determine the oxidation state of protein-bound, small metal co-factors through x-ray crystallography, and show the influence of total absorbed dose on these experiments.
Here we present a novel conveyor belt-based sample delivery system for serial synchrotron crystallography (SSX). It is optimized for fast installation at beamlines, ease of use, low sample consumption and precise adjustment of several sample delivery parameters like ligand concentration, pH, sample temperature and delay time. Through combination of these parameters, CFEL TapeDrive 2.0 enables multidimensional SSX experiments.
Our new environmental enclosure for fixed-target, serial crystallography enables full control of both the temperature and humidity. This enclosure provides access to time-resolved, X-ray diffraction experiments in a wide temperature range from below 10 °C to above 80 °C. We demonstrate changes in the electron density of a hyperthermophile enzyme as a function of increasing temperature and time.
We show how to design an automated phase-analysis model based on a Convolutional Neural Networks (CNN). A framework for the efficient generation of simulated diffraction scans is developed, since real measured and labeled scans are hardly available. Using this synthetic database, a CNN is parameterized, trained and compared against the manual analysis. As a supportive approach, a denoising autoencoder is presented, to be used to eliminate background and other disturbing effects from the signal
The development of novel materials with enhanced performance is a continuous process mainly driven by everyday demands. Optoelectronics is an excellent example of a field where constantly growing societal demands in energy consumption have forced material evolution to speed up. Metal-organic frameworks (MOFs), crystalline porous materials consisting of organic and inorganic building blocks, have been evaluated as promising candidates for a variety of renewable energy applications.
We show that thermal diffuse scattering is sensitive to correlated disorder. We utilise the family of disordered rocksalts KBr$_{1−x}$Cl$_x$ as our model system and analyse the experimentally observed single-crystal X-ray diffuse scattering. Using supercell lattice dynamical calculations we explicitly account for the changes to the dynamics of a system due to correlated disorder.
Here, we propose a theoretical framework and an algorithm for the recognition of ferroelastic domains using high-resolution X-ray diffraction / reciprocal space mapping. We adapt the existing geometrical theory of twinned ferroelastic crystals for the analysis of X-ray diffraction patterns.
A systematic case study of the molecular signatures that can be observed in the 3D-Δ-PDF is presented. We will highlight the reason behind broad regions of negative 3D-Δ-PDF density and explain why situations arise in which intramolecular Patterson vector are not observed in the 3D-Δ-PDF. In combination with current advances in initial data processing we will lay out the basis for a systematic 3D-Δ-PDF atlas.
This presentation will show the results of structural characterizations of MOFs using the X-ray single-crystal and powder diffraction methods.
Macromolecular crystallography (MX) can identify compounds like fragments in their 3D structural context of the protein target, in enhanced through-put. At the MX beamlines at BESSY II, a workflow including dedicated tools, efficient compound libraries and convenient software solutions was established and optimized to provide for efficient screening. Developments like the F2X libraries, the EasyAccess Frame, fspipeline and FragMAXapp elevate the user experience and screening efficiency.
An efficient fragment screening pipeline was set up for a global player from pharmaceutical industry. 1000 crystals were prepared at NUVISAN ICB's high-throughput crystallography platform. Beamline P14 at EMBL Hamburg was chosen for data collection and MOLOX performed this service here. Data processing and structure determination was done by the client. More than 87% of the crystals yielded a dataset of sufficient quality for downstream analyses. Median resolution over all datasets was 1.84 Å.
The crystal structures of adenosine monophosphate deaminase (AMPD) from Arabidopsis thaliana were determined in an unligated form and in complex with the herbicidally active natural compound conformycin phosphate. Comparison of the structures revealed large conformational changes upon ligand binding and allowed a detailed view into the enzyme’s mechanism. The results were used for the mechanism and structure based design of new AMPD inhibitors.
The selenoprotein GPX4 is a potential cancer drug target. Inhibitors covalently target the active site selenocysteine. Co-crystallization with covalent inhibitors initially failed, most likely due to heterogenous covalent modification. A mass spec-based approach to monitor cysteine modification, together with a surface cysteine mutation, enabled the structure determination of GPX4 with the covalent inhibitor ML162 and opens the path to further inhibitor co-complex structures of this drug target.
We determined high resolution structures of human GCH1 and GCH1-GFRP complexes by cryoEM and X-ray crystallography and studied the mechanisms of allosteric regulation by biophysical methods. Inhibition of the enzymatic activity, a drug discovery target in the field of pain disorders, is not a result of hindrance of substrate binding, but rather a consequence of accelerated substrate binding kinetics.
High-entropy oxides (HEO) are a new class of materials containing five or more metal cations in a single-phase solid solution. For the first time, we show that high-entropy versions of mullite-type materials can be synthesized exemplarily shown in the form of 5 new compounds e.g. Bi2(AlGaFeMn)O9 and (Nd,Sm,Y,Er,Eu)2Mn4O10. The crystallized products as well as their formation are characterized by a combination of scattering, spectroscopic and microscopic techniques.
Effects of Fe ↔ Al substitution on SFCA-I-type compounds with general formula A40O56 (A: Ca, Al, Fe3+, Fe2+) have been studied using single-crystal X-ray diffraction. The present investigation provides a detailed crystallographic analysis on the impact of chemical variations on a compound that is of relevance for the field of applied mineralogy related to the technologically important process of iron-ore sintering, where it represents the binding matrix that keeps the sinters intact.
In this study, we have investigated the influence of high-pressure on the structure of hydrous SiO2 glass by a combination of high-pressure Raman spectroscopy and X-ray Raman scattering (XRS) measurements. Previous data of anhydrous SiO2 glass serve as a reference. A detailed analysis of the SiO2 network of both compounds is provided. Moreover, we discuss the role of water in the glass structure of anhydrous SiO2. Our results imply that the water may play a key role in the melting processes.
Crystalline magnesium stearate has been extensively used in pharmaceutical and other industries for decades. However, its crystal structure was not known. We present here the structure of the magnesium stearate trihydrate as determined from X-ray diffraction data of a micron-size single-crystal measured at a 4th generation synchrotron facility. Despite the small size of the single-crystals and the weak diffraction, it was possible to reliably determine the positions of the non-hydrogen atoms.
We studied the structure of UO2 and its temperature dependence from 300 K to 20 K using synchrotron single crystal diffraction. Our samples were UO2 single crystals with a close stoichiometry, confirmed by Raman spectroscopy measurements. Anomalies in lattice parameters will be discussed as well as electron density measurements both above and below the magnetic phase transition, which is believed to lead to distortions in the oxygen sublattice and thus symmetry reduction.
In solid-state chemistry, there is an intriguing number of binary systems lack characterization, especially in combination with the element beryllium. The limited knowledge promises a rich and unusual structural chemistry of this element. The few results concerning Be pnictides include the disordered diamond-like structure of BeP2. Preliminary work based on qualitative evaluation of powder X-ray diffraction data of BeAs2 and BeSb2 indicates related structures for both compounds. Precise structural data require very accurate diffraction data due to the large difference in scattering factors. Despite the simple stoichiometry, complete structural analysis proved difficult as the crystals obtained are much too small for laboratory data collection. We now employed a combined approach using microfocused synchrotron radiation, electron diffraction and HRTEM.
While anticipating the commissioning of the high-intensity time-of-flight neutron powder-diffractometer POWTEX, great efforts were made to optimally exploit the instrument characteristics for future multidimensional Rietveld refinements. The first test data were acquired at the POWGEN instrument of the SNS (Oak Ridge National Laboratory) but using a small segment of the tailor-made POWTEX detector. The raw-data reduction was challenging, and the instrument description required careful attention, as it was a one-of-a-kind experimental set-up.
This work focuses on three selected subtopics: the optimization of raw data reduction, thereby proving the transition to an asymmetric profile description to be necessary and successful, and two additional approaches, to be addressed below.
Contamination with diffraction from ice crystals can negatively affect, or even impede, macromolecular structure determination and therefore detecting the resulting artefacts in diffraction data is crucial. However, once the data have been processed it can be very difficult to automatically recognize this problem. To address this, a set of convolutional neural networks named Helcaraxe has been developed which can detect ice-diffraction artefacts in processed diffraction data from macromolecular crystals.
Our work shows that the multi-dimensional pattern-recognition abilities of convolutional neural networks are a valuable addition to the toolbox of diffraction data analysis. Helcaraxe is currently already in use in the Coronavirus Structural Task Force pipeline and has been integrated into the newest version of AUSPEX.
3D electron diffraction determines the electrostatic potential, which is dominated by the positively charged nuclei and affected by chemical bonds. We observe this effect from the refined coordinates of hydrogen atoms using the independent atom model, suggesting that aspherical atom models should be used.
Transition-metal nitrides tend to form structures with variable compositions. The catalytic activity of cobalt molybdenum nitrides in ammonia synthesis is highly influenced by the composition of the catalyst. Three mixtures of cobalt(II) nitrate and ammonium heptamolybdate with a controlled molar ratio of Co:Mo (2:1, 1:1, 1:2) were prepared by simple mixing. The obtained mixtures were reduced under an ammonia atmosphere with a simultaneous collection of powder X-ray diffraction patterns.
The conversion of Bi$_2$W$_2$O$_9$ to H$_2$W$_2$O$_7$ via HCl treatment has been investigated with in-situ Raman spectroscopy and total scattering / PDF analysis. Previous reports on the selective leaching mechanism of the bismuth oxide interlayer could be verified on the basis of the atomic structure. Our study additionally reveals different rates for the interlayer break-down and subsequent realignment processes resulting in a loss of structural coherence and thus long-range order.
Analysis of the crystallite size data with different approaches utilising X-ray diffraction might lead to ambiguous results. For this reason, the use of different analytical techniques is required to confirm the XRD analysis. In the presented study a nanocrystalline iron was also examined with transmission electron microscopy to compare complementary measurements of crystallite sizes.
We synthesized [Hpyz]$_4$[Sb$_{10}$I$_{34}$] (pyz = N$_2$C$_4$H$_4$), which features the largest discrete halogenido pentelate anion yet. Ions of this type with the general formula [Sb$_{2n}$I$_{3n+4}$]$^{4−}$ are known for $n$ = 1 - 5. With this series of compounds at hand we investigated the influence of the anion size on the optical band gap by experimental and theoretical means to shed some more light on the electronic structure of iodido antimonates close to the absorption edge.
Crystal structure of the complexes of carboxylated pillar[5]arene, a water-soluble macrocyclic host, with guanidine and amidine drugs (eg. alexidine and pentamidine) provide important information on the host-guest interactions and self-assembly in the solid state. Such complexes can potentially be used in the design of drug delivery systems.
Spin crossover compounds have been recognized as promising candidates, which exhibit large barocaloric effects. From the synchrotron structural data, the temperature dependence of the Fe-N distances can be used to determine the high spin fraction. Then by fitting the temperature dependence of the high spin fraction, we obtained the change in entropy, the change in enthalpy, and the cooperativity.
Pillarplexes are tubular supramolecular organometallic complexes containing macrocyclic NHC-ligands and eigth metal ions. The structural self-assembly of these motifs is predicted to be governed by non-covalent interactions between the pillarplex cation and its surrounding. Herein, we investigated possible non-covalent interactions with Full Interaction Maps, crystal structure analysis and Hirshfeld surface analysis.
During the search for novel topological insulators, new fully and partially substituted pseudo one-dimensional compounds were discovered. Extensive investigations into the synthetic pathway via differential scanning calorimetry lead to the two subiodides of the type Bi$_2$[PtBi$_6$I$_{12}$]$_3$ being isolated and synthesized independently. The six weak inter-cluster bridges between the strands, in combination with the strong spin-orbit coupling, could lead to interesting non-trivial topology.
Previous Hirshfeld Atom Refinement approaches have used non-periodic calculations in order to obtain atomic form factors. We have implemented HAR on the basis of periodic PAW calculations and want to present details and results of this new approach.
In our work we synthesized polycrystalline Rb3-xKxCu3AlO2(SO4)4 with varying Rb:K ratios. In the experiments we outlined the optimum growth conditions for Rb substituted alumoklyuchevskite synthesized from powder mixtures. First results suggest that Rb and K show a complete miscibility in the polycrystalline powder. In addition, O2 atmosphere is beneficial for building the synthesized phase. In accordance with literature, a change in magnetic properties was observed for different Rb:K ratios.
Molecular crystals are usually brittle. This fragility poses challenges for their application. Recently, mechanical flexibility in crystalline materials has been discovered. These materials can be divided into being plastically (irreversibly) or elastically (reversibly) bendable. Here we report 4-bromo-6-[(6-chloropyridin-2-ylimino)methyl]phenol (CPMBP) as a plastically bendable crystal and promising candidate for future waveguide technologies.
Multiple Edge Anomalous Diffraction (MEAD) was used to determine the cation order of Cu2FeSnS4, Cu2GaGeS4, Cu2ZnSnSe4, Cu2ZnSiSe4 and Cu2ZnGeSe4 quaternary chalcogenide semiconductors, which crystallize in either kesterite, stannite or wurtz-kesterite type structure.
Here, we used Brillouin spectroscopy to determine the sound velocities and elasticity of dolomite-ankerite solid solutions along the CaFexMg1-x(CO3)2 join (x = 0.05, 0.63) at ambient conditions to evaluate the effect of Fe on the elastic properties. The presence of 63 mol% of the CaFe(CO3)2 component in dolomite-ankerite solid solutions, leads to a lowering of the acoustic velocities (-8% for vp and -13% for vs), bulk modulus K (-10%), and shear modulus G (-13%), compared to pure dolomite.
We will present the synthesis, crystal structure, thermal expansion, Raman spectra and heat capacity of Ca-guanidinium formate ([C(NH$_2$)$_3$][Ca(HCOO)$_3$]), a new member of the family of metal-organic perovskites. Ca-guanidinium formate shows an extraordinary strong negative thermal expansion between 100 K and 400 K within the crystallographic (001) plane. Perpendicular to this plane, along $\mathbf{a}_3$, the crystal structure expands with increasing temperature very strongly.
Binary vanadium oxides have attracted considerable attention due to their electronic and magnetic properties. We studied V2O5 and V6O13, two members of the Wadlsey phase series, under high pressure with single crystal diffraction in diamond anvil cells and under HP-HT conditions in situ using a multi anvil press.
Coordination polymer [Cu(2,3-pdc)H2O]n was obtained by solvothermal synthesis in a Berghof BF100 pressure reactor using QUIN (quinolinic Acid) and Cu(HSO3)2 as substrates. The resulting compound crystallizes in triclinic system, in a space group of , with a = 7.434(3) Å, b = 7.523(4) Å, c = 7.881(3) Å, α = 62.68(5)o, β = 79.02(5)o, γ = 78.90(5)o, V = 381.5(3) Å3, Z = 2.
Cu20Te11Cl2 is a new polymorphic Cu-ion conducting material with order-disorder phase transitions occurring at 288 and 450 K. The α-β-phase transition occurs via symmetry reduction from the hexagonal to the orthorhombic crystal system that is attended by twinning and additional quintuplication of the a- and duplication of the c-axis. The compound features dynamic disorder in the cation and statistical disorder in the anion substructure.
The novel material Cu3SeyTe1-y was synthesized and characterized crystalografically. The material behaves according to Vegard´s Law, indicating the formation of a solid solution in the range between 0.1 and 0.6. All compositions belong to the cubic space group Pm-3n according to single crystal X-Rax diffraction measurements. Ionic conduction and thermoelectric characterization are currently being analysed.
In this presentation, we will inform the scientific community as well as industrial customers about research possibilities and latest technical developments at the Powder Diffraction and Total Scattering Beamline P02.1 at PETRA III, DESY.
The latest developments in optimization of clamp cells for neutron scattering at MLZ will be presented.
Within the last decade high-pressure studies have received an increase of interest. A major challenge in the field of high-pressure crystallography is the acquisition of data of sufficient quality and completeness for a successful structure determination. This presentation will be reviewing recent advances in hardware development and highlight the latest improvements in software, which help in tackling the problems with data acquisitions in high-pressure experiments using a Bruker D8 VENTURE.
Its about the crystal structure of the Chloride-Poor Oxosilicate Ce3Cl[SiO4]2
Science communication is becoming an important aspect in today's sciences. It is evident that it is necessary for scientists not only to sit in their ivory towers and conduct research, but also to communicate this research interactively with other scientists and to involve the interested public in new scientific developments. Here it is not only important to bring research closer to adults and young people, but the involvement in current research should take place as early as possible.
Solid solutions (SS) are single multicomponent solid phases for which the constituent component ratio can vary in continuum. Along with the composition, also properties of solid solutions are modulated. The changes in composition are often accompanied by a continuous change in some physical and/or chemical properties (e.g., density, solubility, melting point), and more complex properties such as solid-state luminescence and phosphorescence properties, that are composition-dependent.
The uncommonly used wavelength Cu K-beta showed significant improvement for the structural models of the metal-organic framework subgroup called 'sponge crystals'. The advantages towards the commonly used wavelength Cu K-alpha are a shorter wavelength and thus higher resolution with less elemental absorption and thus less background or sample decay. Cu K-beta also inherits no high-angle peak splitting. In this way, better crystallographic models can be obtained for the crystalline sponge method.
Crystal structure of the complexes of carboxylated pillar[5]arene, a water-soluble macrocyclic host, with guanidine and amidine drugs (eg. alexidine and pentamidine) provide important information on the host-guest interactions and self-assembly in the solid state. Such complexes can potentially be used in the design of drug delivery systems.
Spin crossover compounds have been recognized as promising candidates, which exhibit large barocaloric effects. From the synchrotron structural data, the temperature dependence of the Fe-N distances can be used to determine the high spin fraction. Then by fitting the temperature dependence of the high spin fraction, we obtained the change in entropy, the change in enthalpy, and the cooperativity.
We synthesized [Hpyz]$_4$[Sb$_{10}$I$_{34}$] (pyz = N$_2$C$_4$H$_4$), which features the largest discrete halogenido pentelate anion yet. Ions of this type with the general formula [Sb$_{2n}$I$_{3n+4}$]$^{4−}$ are known for $n$ = 1 - 5. With this series of compounds at hand we investigated the influence of the anion size on the optical band gap by experimental and theoretical means to shed some more light on the electronic structure of iodido antimonates close to the absorption edge.
During the search for novel topological insulators, new fully and partially substituted pseudo one-dimensional compounds were discovered. Extensive investigations into the synthetic pathway via differential scanning calorimetry lead to the two subiodides of the type Bi$_2$[PtBi$_6$I$_{12}$]$_3$ being isolated and synthesized independently. The six weak inter-cluster bridges between the strands, in combination with the strong spin-orbit coupling, could lead to interesting non-trivial topology.
Transition-metal nitrides tend to form structures with variable compositions. The catalytic activity of cobalt molybdenum nitrides in ammonia synthesis is highly influenced by the composition of the catalyst. Three mixtures of cobalt(II) nitrate and ammonium heptamolybdate with a controlled molar ratio of Co:Mo (2:1, 1:1, 1:2) were prepared by simple mixing. The obtained mixtures were reduced under an ammonia atmosphere with a simultaneous collection of powder X-ray diffraction patterns.
The isothermal crystallization kinetics of hen-egg-white Lysozyme has been investigated by means of a time-resolved neutron diffraction experiment for almost 3 days, starting from a supersaturated solution of Lysozyme until the growth of crystals. The analysis of the small angle neutron scattering curves from the Lysozyme solution reports on the number of dissolved lysozyme molecules.
The conversion of Bi$_2$W$_2$O$_9$ to H$_2$W$_2$O$_7$ via HCl treatment has been investigated with in-situ Raman spectroscopy and total scattering / PDF analysis. Previous reports on the selective leaching mechanism of the bismuth oxide interlayer could be verified on the basis of the atomic structure. Our study additionally reveals different rates for the interlayer break-down and subsequent realignment processes resulting in a loss of structural coherence and thus long-range order.
The presented study focuses on the synthesis and characterization of three different perylene-based MOFs, for the investigation of photophysical energy transfer and its conversion to shed light on structure-property relationships. Photophysical characterization of the obtained materials showed characteristics of H-type aggregates being dominant. The solid-state structures as obtained by SC-XRD are presented and photophysical implications thereof as well as potential applications are discussed.
A rare phenomenon inversion in mullite-type RAlGeO5 for R = Y, Sm – Lu
Verbindungen der Zusammensetzung $A_{49}$Ga$_{2}$Tl$_{108}$ ($A$ = K, Rb) mit Ga im Zentrum von Tl$_{12}$-Ikosaedern, die im K$_{49}$Tl$_{108}$-Strukturtyp kristallisieren. Die Strukturen lassen sich als hierarchische Varianten des Cr$_{3}$Si-Strukturtyps beschreiben, wobei die Ikosaeder die Si-Positionen besetzen, während sich einfach überkappte zentrierte hexagonale Antiprismen auf den Cr-Positionen befinden.
A crystal engineering approach (salt formation, cocrystallization, etc.) has been applied toward the development of enantiomeric resolution protocols for pharmaceutical compounds.
Monazite is being investigated as a host for long-term storage of radioactive waste, especially actinides. While trivalent cations can easily be incorporated via a simple substitution reaction the incorporation of tetravalent ions has proven difficult. Synthesis of the solid solution LaPO4 – Ca0.5Ce0.5PO4 has been attempted resulting in an unexpected non-linear change of lattice parameters. Possible causes for this behavior will be investigated via various analytical techniques.
Three unprecedented mixed anionic hydrides were synthesized. Here we present the first representatives of the materials classes of the phosphate, borate and lastly the sulfate hydrides. The compounds were analyzed by the means of X-ray and neutron diffraction. The abundance of Hydride next to the complex anions is proven by vibrational spectroscopy and 1H MAS NMR spectroscopy in combination with DFT-calculations, proving the unprecedented abundance of hydrides next to the complex oxoanions.
Mercury-rich amalgams serve as ideal candidates for the investigation of structure-property-relationships in polar intermetallic phases. Within this compound class, the Gd14Ag51 structure represents the aristotype of many binary mercury-rich amalgams. By single-crystal and synchrotron X-ray diffraction, we have characterised three new ternary amalgams. With each compound containing more than 100 atoms per unit cell, these structures possess high structural complexity.
The correlation between thermal expansion, Debye temperature and the Lindemann criterion will be discussed
Five metastable binary rare-earth trisilicides RESi3 (RE= Gd, Tb, Dy, Er, Tm) are synthesized by high-pressure high-temperature synthesis (9.5 GPa, 823-923 K). X-Ray powder diffraction data evidence that the crystal structure of the compounds is isotopic to that of CaGe3 and lattice parameters are refined. Magnetic measurements on DySi3 reveal Curie-Weiss paramagnetic behaviour and antiferromagnetic ordering at low temperatures.
Crystallographic fragment screening facilitates the identification of weak but efficient small molecules (fragments) while elucidating their binding mode and position. This enables structure-guided optimization of bound fragments into potent modulators. Here, the ~1000-fragment large F2X-Universal Library was screened against a spliceosomal protein-protein complex and resulted in hundreds of hits.
The nature of the H adsorption process on the SMoSe Janus layer (JL) is studied using DFT simulations. The Si doping leads to differential charges and hence increases H adsorption in JLs.
Im Rahmen von Untersuchungen zur Rolle des Magnesiums in ternären Zinkiden und Cadmiden der schwereren Erdalkalimetalle wurden in den Titelsystemen die Mg/Zn-Phasenbreiten neuer Verbindungen des Th$_6$Mn$_{23}$-, Sr$_3$Mg$_{13}$-, Eu$_3$Mg$_{16}$-, CaCu$_5$/BaZn$_5$-, Th$_2$Zn$_{17}$/Th$_2$Ni$_{17}$- und des BaCd$_{11}$-Typs präparativ, röntgenographisch und bindungstheoretisch untersucht.
A number of crystal structures of orthometalate A3MO4 reported in a cubic symmetry may be erroneously assigned. They belong to the orthorhombic K3NO4 structure type (space group Pnma). On the new compounds Cs3TaO4 and Cs3NbO4 we show parameters responsible for the wrong assignment, give an oversight over the known phases and discuss examples for structural phase transitions to a cubic modification.
YLID crystals have been used as test crystals for X-ray diffractometers. But, no charge density evaluation has been performed for this crystal. It is certainly more meaningful if we compare, e.g., hydrogen anisotropic displacement parameters and the residual density distribution to evaluate our diffractometer. So, for data quality evaluation of a diffractometer, quantum crystallographic procedures are helpful.
Synthesis and crystal chemistry new vacancy-ordered quadruple perovskite Rb4CuSb2Br12.
Understanding the lithium intercalation into graphite is crucial for lithium ion batteries, however still incompletely understood.
To improve the understanding of the phase transition mechanism, we review published binary stage-1 GIC structures from the ICSD-database, fundamental structural aspects like bonding distances and packing arrangements and explore their symmetry relationships applying group-subgroup considerations. This will help in the analysis of measured diffraction data of LIBs.
This research aims at the local structure characterization of carbon-nitrogen polymers which function as support materials for single-atom catalysts as well as the as-synthesized catalysts. Here, the focus lies on graphitic carbon nitride on which 1wt.% Pd was immoblized. Different structural and spectroscopic methods like pair distribution function analysis and X-ray photoelectron spectroscopy were applied in order to draw structure-performance relationships.
Novel predicted and previously synthesized BaS phases have been calculated and subjected to extreme pressures. The structure-property relationship and in particular metalization of BaS has been investigated. Here, we present structure prediction, high-pressure effect, and properties investigation of superhard B6O. Finally, we show one unknown Cr2SiN4 compound calculated using a combination of the theoretical methods, and behavior under high pressure has been investigated.
Stable and metastable modifications inside of an ionic Ce-O-N compound with the compositions Ce2ON2 and Ce3O3N have been identified. The Ce2ON2 has been found as a best candidate with Ce4+ charge, even in the extreme conditions, [1,2] while Ce3O3N system is predicted for Ce3+ ions. Structure candidates for both compositions have been obtained after exploring the energy landscape for different pressure values and using empirical potentials.
Synthesis and characterization of indium-containing sillenite
This abstract is about covalently functionalized nanoparticles which are analyzed by in-depth NMR studies and HR-TEM. The particles carry an amino group which is converted to an azide, which was then used to bind functional ligands by copper-catalyzed alkyne-azide cycloaddition (CuAAC).
Fragment based drug design of NSP3 domains from SARS-CoV2 with a focus on Plpro.
SARS-CoV-2 main protease (Mpro) is an important target for small-molecule COVID-19 antivirals. We use neutrons to determine protonation states of ionizable residues in Mpro informing computer-assisted and structure-based design. Several neutron crystal structures were determined, revealing protonation state modulation upon inhibitor binding. This information is used to design novel inhibitors and to perform structure-activity relationship studies guided by virtual reality structure analysis.
The TSC complex is a tumor suppressor regulating cellular growth. We investigated the structure of the TSC1 subunit and identified a coiled-coil domain that binds TSC2, a central helical domain that mediates oligomerization of TSC1 and an N-terminal domain that binds to lipids via a basic interface. These findings reveal a role of TSC1 in by mediating TSC complex membrane recruitment and suggest a function in the formation of TSC supercomplexes.
Type III secretion systems (T3SS) are bacterial molecular assemblies employed to inject effector proteins in host cells. We present the structure of a T3S export gate with a substrate:chaperone complex. Following a divide-and-conquer strategy, we first determined the structure of the previously uncharacterized substrate:chaperone complex at higher resolution. Our ternary complex marks the first instance where the substrate directly binds to the export gate instead of mediation by the chaperone.
Type VII secretion systems export proteins across the mycobacterial cell envelope into the extracellular environment. While it is still unknown how proteins cross the highly impermeable outer mycobacterial membrane, our recent cryo-EM structure has provided insights into the architecture of the base of this system- the part spanning the cytoplasmic membrane. In this presentation, this structural model, its mechanistic implications and possible transport models will be discussed.
We report the crystal structure of CRISPR-Lon, a type-III CRISPR related protease that is activated by cyclic oligoadenylates. The protein is a soluble monomer and contains a SAVED domain that accommodates cA4. Further, we show that CRISPR-Lon forms a stable complex with the 34 kDa CRISPR-T protein. Upon activation by cA4, CRISPR-Lon specifically cleaves CRISRP-T, releasing CRISPR-T23, a 23 kDa fragment that is structurally very similar to MazF toxins and is likely a sequence specific nuclease.
The bacterial transcriptional regulator RutR was shown to be lysine acetylated at five distinct sites in the DBD and LBD. However, how lysine acetylation affects RutR function is not known. Applying genetic code expansion using a synthetically evolved acetyl-lysyl-tRNA-synthetase (AcKRS3)/tRNACUA (MbPylT)-pair from Methanosarcina barkeri, we produced site-specifically lysine-acetylated RutR proteins in yield and purity suitable for biophysical studies including X-ray crystallography.
Polymer-assisted grinding is shown to be an effective method to remove solvent molecules from a crystal solvate. The desolvation can be tuned based on polymer type and amount. Products are characterized by x-ray diffraction, pair distribution function analysis, Raman spectroscopy, and theoretical energy calculations to investigate the structural implications and mechanism at hand.
Gallium arsenide is one of the most important materials for optoelectronic. During manufacturing, the presence of like dislocations may influence the fabrication yield and the performance of the devices. This study provides a deeper understanding of dislocation generation and development in GaAs wafers with mechanical surface damage exposed to thermally induced stress investigated by X-ray diffraction imaging methods.
(Mg,Zr):SrGa12O19 (SGMZ) single crystals are analyzed by lab-based X-ray imaging techniques to study the interplay of compositional variations and local stress. Based on quantitative rocking curve imaging, we can disentangle lattice strain due to stress and composition changes. We found that the formation of a small (0001) facet at the center of the growth interface leads to reduced dopant concentration which then causes elastic strain as it is also seen in birefringence measurements.
Polymorphism study is essential for selecting the most adequate solid form for a drug product. Therefore, it is always recommended to conduct a thorough search of the crystalline solid forms.
An effective approach for solid form screening combined with crystal structure determination is of considerable importance. However, as growth of suitable crystals for X-ray crystallography may be time consuming, Electron Diffraction on nano-sized crystals represents a significant advantage.
Off-stoichiometric kesterite-type Cu2ZnSnSe4 (CZTSe) is doped with Li, Na, K by two different methods. Adding dopants as chlorides directly during the solid-state synthesis from pure elements is compared to a post deposition approach. The samples are analysed by XRD with subsequent Rietveld refinements in combination with EMPA for spatially resolved compositional information and bandgap energy is characterized by DRIFTS.
Two newly discovered compounds, Rb2Zn(TeO3)(CO3)∙H2O and Na2Zn2Te4O11, both crystallize with order-disorder (OD) structures comprising of layers and feature a high stacking fault probability. Both cases are unusual in that the OD character is due to different translation lattices of the adjacent layers. The stacking disorder is visible in the diffraction patterns in the form of diffuse streaking on the characteristic reflections.
We demonstrated the synthesis of carbonates containing [CO4]-groups at moderately high pressures (20-30 GPa) by reacting carbonates with oxides or CO2. These carbonates have different chemical compositions than the well-known ‘conventional’ carbonates (MeCO3) and are enriched either with the metal oxide or with CO2. Here we will give an overview of carbonates containing [CO4]-groups and will present crystal-chemical aspects of [CO4]-groups in comparison to [SiO4] and other [MO4] complex anions.
We synthesized novel Sr-carbonates at moderate pressures and temperatures in a laser heated diamond anvil cell. We obtained the sp$^3$-carbonates Sr$_2$[CO$_4$] and Sr$_3$[CO$_4$]O with isolated CO$_4$ tetrahedra and both phases can be recovered at ambient condition. We also synthesized Sr[C$_2$O$_5$] by a reaction of Sr[CO$_3$] with CO$_2$ which is the first inorganic pyrocarbonate salt.
For alkali metal thallides in the ratio A:Tl 1:2 two main type structures (A15Tl27 (A= Rb, Cs) and K49Tl108) are known in literature. The single crystal X-Ray analyses of Cs2.27K12.73Tl27 and Rb49Tl∼110 clearly prove, that the type structures are not limited to a particular alkali metal. Apparently, the occupation of certain sites and slight changes in the thallium content account for the observation of the respective structure type.
The design of novel ligand systems allows for ever more control over structural and hence reactive capacities of organometallic systems. We discuss the development of a novel family of pendant-phosphine amide ligands, which show a diverse range of fluxional binding characteristics, and even reactive non-innocent, thus lending a new set of tools to the modern synthetic chemist.
We studied the elasticity of metal-guanidinium formates (metal=Cu, Zn, Mn, Co, Ca, Cd) with experimental and theoretical techniques, among those resonant ultrasound spectroscopy, Brillouin spectroscopy and density functional theory. We found a good agreement between the different techniques and the theoretical data. Our results show a systematic variation of the bulk modulus as a function of the radius of the metal cation, indicating that the elastic behavior is mainly due to packing density.
In this work we show the crystallization of a new low-dimensional spin compound Cs3Cu3Cl7.6Br0.4OH with weakly coupled Cu-triangles. In addition, the x-ray diffraction of this new compound results in a monocline structure with space group P21/c, which is isostructural to Cs3Cu3Cl8OH. The differences of distances and angles due to Br doping are very small, but, nevertheless, those are important to detect the distinct variations in the magnetic properties of both investigated compounds.
A recent research direction related to ABX$_3$ perovskites is the use of molecules on the A and/or X-site, a development that has proved fruitful for photovoltaics, (improper) ferroelectrics and barocalorics. Here an information theory-based rating scheme is applied to obtain structural complexities of various perovskite classes and it is shown that increased chemical diversity is synonymous with increased structural complexity which scales with the size of the pseudocubic ReO$_3$-type network.
GeV ion irradiation and high static pressures are combined in order to investigate ion-induced structural changes on pressure-induced phase transitions in nano-materials. We introduce the synthesis of bismuth nanowires and discuss beam-induced morphological and structural changes. Moreover, the technical capabilities of the GSI ion accelerator and a novel experimental setup developed for the irradiation of samples pressurized inside diamond anvil cells (DACs) will be presented.
We discuss symmetry-dependent magnetic, electric, and optical phenomena characteristic of materials with unconventional ferroic orders such as ferro-toroidal, ferro-axial, and ferro-quadrupole orders. The phenomena include magnetoelectric effect, nonreciprocal directional dichroism, and electrogyration. Furthermore, we show ways to spatially visualize domain structures in such unconventional ferroic materials.
Rigaku Workshop Part2
Rigaku Workshop.
Orientation-field-based phase-field models developed in the past decade will be presented, which incorporate homogeneous and heterogeneous nucleation of growth centers, and several mechanisms for the formation of new grains at the perimeter of growing crystals termed "growth front nucleation". This approach enables the modeling of complex polycrystalline structures. Microscopic aspects of growth front nucleation, quantitative simulations, and possible future directions will be discussed briefly.
Continuous development in microfocus sources means that this technology remains the most versatile and widely used for single crystal X-ray diffraction. Small, high intensity beams of several wavelengths allow the crystallographer to match the experimental demands and ensure that the most accurate structures can be obtained from a variety of crystal types. We will briefly discuss how selection of the appropriate source wavelength influences the data quality and measurement times.
The thermal beamport SR8 at the research neutron source Heinz Maier-Leibnitz (FRM II) will be optimized and completely rebuilt in the coming year. This will allow the simultaneous operation of the three independent monochromatic powder diffractometers SPODI, FIREPOD and ERWIN at this beamport. The unique characteristics of each of the three versatile instruments, which will be able to cater for a wide range of experimental demands, will be presented in detail.
The recent upgrade of the Rossendorf Beamline [1] at ESRF allows simultaneous collection of diffraction (SCXRD and PXRD) and spectroscopy (XRF and XANES). We will present some recent results to demonstrate the experimental opportunities.
Mechanochemistry has become an important method for the synthesis and conversion of materials. Extending the mechanical impact to catalysis opens a broad area of new reaction pathways. In this contribution, three examples for the successful development and implementation of an in situ mechanochemical setup for synchrotron sources will be discussed.
Using the amide I band, infrared spectroscopy can give information on the fold of the protein and also allows to follow aggregation phenomena. Small angle neutron scattering also reports on the global structure of proteins in solution and can give information on the shape of growing aggregates or folded proteins in solution. We would like to explore the capabilities of quantum cascade lasers (QCLs) for the combination of small angle neutron scattering with infrared spectroscopy.
Hybrid Photon Counting (HPC) allows for direct detection of X-rays in single-photon counting mode. HPC provides a number of benefits such as a sharp point-spread function, the absence of detector background, and outstanding dynamic range. High-Z sensors enable high quantum efficiencies for high X-ray energies and bring the benefits of HPC to hard X-ray applications. This presentation outlines the features and advantages of EIGER2 CdTe and shows examples of the benefits of HPC with CdTe sensors.
This presentation will feature dedicated instrumentation for 3D ED/MicroED and a couple of interesting datasets.
With the recent launch of the XRDynamic 500 automated multipurpose powder X-ray diffractometer, Anton Paar has expanded its portfolio of high-performance X-ray analysis solutions which also includes SAXS instrumentation, non-ambient XRD attachments, X-ray sources, and X-ray optics.
XRD and SAXS are vital tools to study the atomic and nanoscale structure of materials in both fundamental and applied research environments as well as in industrial research and quality control areas. The methods are also complementary and can reveal information about the crystal structure, phase purity, pore size, specific surface, particle/crystallite size, and more, which are fundamental in understanding the physical and chemical properties of a material.
This contribution will showcase the latest developments from Anton Paar in the fields of XRD and SAXS, including application examples to showcase the benefits for laboratory X-ray measurements.
STOE has a long-standing tradition in building state-of-the-art x-ray diffractometers that are well known for their mechanical stability and flexibility. This allows for routine analyses and advanced characterizations to be performed equally well on STOE diffractometers.
This talk highlights recent advances in instrumentation for STOE’s single crystal and powder diffractometers and shows research examples that were limited to large-scale research facilities or relied on custom-made solutions in the past but can now be performed in the home-lab an a STOE diffractometer.
Empirical single crystal growth protocols have several limitations, in both the number of experiments one can reasonably test, the possible experimental conditions attainable, and an overall lack of reproducibility. Good practice can overcome some of these problems.
We describe several common single crystal growth methods, together with the chemical rational behind them, and how to perform them either by hand or using our small-scale medium throughput crystallizers, Crystal16 and CrystalBreeder.
Beamline P11 at PETRA III in Hamburg is a versatile instrument for macromolecular crystallography. The mode of operation has changed from fully onsite to almost exclusively remote operations in the passed two years. Full integration of Eiger2 X 16M and migration of autoprocessing to central cluster have recently increased the speed of data collection. Serial crystallography with tapedrive is offered as an alternative setup. Intergration of MXCuBE and ISPyB are in progress.
Presenting MicroMAX at the MAX IV Laboratory, a macromolecular crystallography beamline that will open to users in 2023. It will give new opportunities by having flexible optics and a flexible sample environment for serial crystallography, time-resolved experiments and other applications. Short pulses, microfocus or a large homogeneous beam, rotation or serial crystallography, photon-counting or integrating detector, light triggering or microfluidics to name a few of the possibilities.
The new ID29 is a beamline for time resolved serial crystallography at the ESRF Extremely Brilliant Source. It is designed to fully exploit the characteristics of the new source and pave new avenues in room temperature experiments with time resolved applications.
The MX group at the Helmholtz-Zentrum Berlin (HZB) is operating 3 state-of-the-art synchrotron beam lines for MX at the BESSY II facility. Currently, the three beam lines represent the most productive MX-stations in Germany, with more than 3800 PDB depositions. BLs14.1-2 are tunable, while beam line 14.3 is a fixed-energy side station. Within this presentation a summary on the experimental possibilities of the beam lines and the ancillary equipment provided to the user community will be given.
DESY - together with collaboration partners - is building a new instrument for macromolecular crystallography exclusively dedicated to high-throughput X-ray fragment and compound screening. The goal is to develop a fully automated endstation with the capability of determining more than 1000 protein structures per 24 hours. The beamline will be open for both academic and industrial users and user operation is expected to commence in 2023.
Rim-modified pillarplex cavitands are presented and structurally discussed. These supramolecular organometallic complexes (SOCs) are tubular-shaped complexes of the size of 1 nm, featuring a pore which allows for guest uptake. The modification of the organic ligand leads to the introduction of structural flexibility in the corresponding SOC. Additionally, complementary hydrogen bonding is enabled, leading to a sheet-wise self assembly of SOCs as crystallographically determined in solid state.
Zeolitic Imidazolate Frameworks (ZIFs) are a large subgroup of metal-organic frameworks, which has been studied for decades. The synthesis in aqueous solution using methylimidazolate (Hmim) and different zinc salts leads to the formation of Zn3mim5XH2O·nH2O with x = Br, Cl and α-Zn3mim5X with x = F, OH phases showing an yqt network. The imcorporation different halide and hydroxide anions into the network effects the de- and rehydration behavior,the spectral proteries and thermal expansion.
We have analyzed the microstructure of LaMO3 perovskites (M=Ni,Co,Fe), which were synthesized by incipient wetness impregnation of mesoporous carbon spheres and subsequent sintering. In the case of LaNiO3, we identified Ruddlesden-Popper shear faults via transmission electron microscopy. We set up a structural model for these defects and fit it to complementary synchrotron and neutron data via Rietveld refinements. Local structure analysis supports the gained results.
Understanding the structural change caused by radiation damage is an essential element in the development of strategies for the safe disposal of radioactive waste. For this purpose, monazite crystals of different chemical composition were synthesized and irradiated with 1.7 GeV Au ions to simulate the radiation damage caused by radioactive decay. Subsequently, the single crystals were characterized by Raman spectroscopy, secondary electron microscopy and single crystal X-ray diffraction.
The system of 1:1:1 cocrystal solvate of caffeine, 4-chloro-3-nitrobenzoic acid and methanol is the first reported example of molecular crystal that exhibits reversible elastic flexibility. Here we show in-situ recrystallization of long flexible acicular single crystals post partial desolvation. This apparent reversible process in accompanied by increased inclusion of the solvent than as grown crystals resulting in larger unit cell volume within the same space group symmetry.
Efficient reduction of 2D grazing-incidence X-ray Scattering (GIXS) data becomes more computational demanding with the increase of detector time-resolution and pixel number.
We present the In-Situ GIXS Heuristic Tool that allows for computationally efficient reduction of GIXS data, giving full access to the raw data while a first reduction can be done directly at the beamline.
Thus this tool enables a quick analysis of big in-situ and operando data sets in order to accelerate data processing.
With the recent launch of the XRDynamic 500 automated multipurpose powder X-ray diffractometer, Anton Paar has expanded its portfolio of high-performance X-ray analysis solutions which also includes SAXS instrumentation, non-ambient XRD attachments, X-ray sources, and X-ray optics.
This contribution will showcase the latest developments from Anton Paar in the fields of XRD and SAXS, including application examples to showcase the benefits for laboratory X-ray measurements.
We present a study of the maximum resolution of the PSC. As an example, a split position of La and Sr with $(0, 0, z = 0.3584)$ has been investigated in the potential high-T super-conductor La$_{0.5}$Sr$_{1.5}$MnO$_4$, I$_4$/mmm. Due to the difference in scattering power of La and Sr, a pseudosymmetric structure solution exists for approximately interchanged $z$-positions. Depending on the relative error of diffraction intensities, we present respective resolution limits for the split position.
At the FRM II neutron source in Garching near Munich the neutron single crystal diffractometer BIODIFF, a joint project of the Forschungszentrum Jülich and the FRM II, is dedicated to the structure determination of proteins. 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.
LDH-phases are forming lamellar layered crystal structures with positively charged main layers and negatively charged interlayers. These phases can generally be given as [Me(1-x)2+ Me(x)3+ (OH)2]x+ [A(x/y)y- · mH2O]x-. Additionally, Lithium (1+) can be incorporated in the structure instead of the metals (2+).
Polycrystalline K3Cu3AlO2(SO4)4 can be successfully produced synthetically. The synthesized phase corresponds to alumoklyuchevskite, and is interesting as a spin liquid material for fundamental research of magnetism. The poster shows the results of the investigations with different characterization methods, i.e. powder x-ray diffraction (PXRD), electron dispersive x-ray analysis (EDX) and difference thermo analysis (DTA).
Using molten salt synthesis we were able to replace Ga in Mo2Ga2C.
In our work we synthesized polycrystalline Rb3-xKxCu3AlO2(SO4)4 with varying Rb:K ratios. In the experiments we outlined the optimum growth conditions for Rb substituted alumoklyuchevskite synthesized from powder mixtures. First results suggest that Rb and K show a complete miscibility in the polycrystalline powder. In addition, O2 atmosphere is beneficial for building the synthesized phase. In accordance with literature, a change in magnetic properties was observed for different Rb:K ratios.
Here we report on the formation of hybrid perovskite methylammonium iodide (MAPbI3) from lead iodide and methylammonium iodide by thermal annealing as observed in situ. We applied in situ grazing-incidence wide-angle x-ray scattering (GIWAXS) to analyze phase and texture information in real-time with our python-based software tool INSIGHT.
The results of the current study show the non-destructive quantification of lithium and electrolyte, their spatial distribution and concentration changes induced by cell fatigue. Combined experimental studies including electrochemistry, X-ray computed tomography and neutron diffraction independently reveal a direct correlation between losses of active lithium intercalated in the graphite anode and those of liquid electrolyte averaged over the volume.
In our recent investigation on MAPbCl3, we found that phase separation occurs in the orthorhombic low-temperature phase, depending on the graining intensity. For lightly ground batches, besides the orthorhombic phase "o1" (space group Pnma, a ≈ 11.2 Å, b ≈ 11.3 Å, c ≈ 11.3 Å) another orthorhombic phase "o2", which has the same space group Pnma as "o1", but a smaller crystal lattice (a ≈ 8.0 Å, b ≈ 11.3 Å, c ≈ 7.9 Å) was observed by us.
Pillarplexes are tubular supramolecular organometallic complexes containing macrocyclic NHC-ligands and eigth metal ions. The structural self-assembly of these motifs is predicted to be governed by non-covalent interactions between the pillarplex cation and its surrounding. Herein, we investigated possible non-covalent interactions with Full Interaction Maps, crystal structure analysis and Hirshfeld surface analysis.
Previous Hirshfeld Atom Refinement approaches have used non-periodic calculations in order to obtain atomic form factors. We have implemented HAR on the basis of periodic PAW calculations and want to present details and results of this new approach.
Molecular crystals are usually brittle. This fragility poses challenges for their application. Recently, mechanical flexibility in crystalline materials has been discovered. These materials can be divided into being plastically (irreversibly) or elastically (reversibly) bendable. Here we report 4-bromo-6-[(6-chloropyridin-2-ylimino)methyl]phenol (CPMBP) as a plastically bendable crystal and promising candidate for future waveguide technologies.
3D electron diffraction determines the electrostatic potential, which is dominated by the positively charged nuclei and affected by chemical bonds. We observe this effect from the refined coordinates of hydrogen atoms using the independent atom model, suggesting that aspherical atom models should be used.
Analysis of the crystallite size data with different approaches utilising X-ray diffraction might lead to ambiguous results. For this reason, the use of different analytical techniques is required to confirm the XRD analysis. In the presented study a nanocrystalline iron was also examined with transmission electron microscopy to compare complementary measurements of crystallite sizes.
The formylglycine-generating enzyme (FGE) plays a key role in the posttranslational modification of the active site of all known human sulfatases. Previously crystallized structures of FGE are missing a surface loop that had to be cleaved off prior to crystallization. Here, we report the first crystallization of human FGE including this loop.
An epitaxial thin film of (LBMTO) was synthesized using pulsed laser deposition technique (PLD) with a desirable thickness of 95 nm. The film grown on SrTiO3 (0 0 1) substrates exhibited a paramagnetic-to-ferromagnetic second order phase transition at 291 K. The as-grown film displays a giant magnetoresisitance (GMR) up to 150% at room temperature under 5T applied magnetic field.
To get further insight into electron spin interactions of at present intensely investigated quantum spin liquid materials, we decided to substitute Lu$^{3+}$ into NaYbS$_2$, which is one of the most promising candidates to host this unique magnetic ground state. In this contribution, we discuss the crystallographic aspects of this solid solution series and give an outlook on the evolution of the electron spin interactions, investigated by ESR spectroscopy and magnetization measurements.
We have investigated the formation of single phase precious metal high entropy alloys such as Pt2AuCuNiSn by in situ powder diffraction at the high energy beamline P21.1 at DESY in Hamburg. We show that precious metal HEAs can be obtained at comparatively low temperature when Sn is included.
In this work, we strive to investigate in how far a successful Hansen & Coppens multipole refinement with subsequent Bader QTAIM analysis of the only slightly disordered compound AlH2MeBOX can be achieved. Bis(benzoxazol‐2‐yl)methandid (BOX) ligands are a family of readily available ligands with easily customizable steric demand. Therefore, BOX ligands are a promising alternative to the ubiquitous NacNac ligands.
Syntheses with lanthanoid metals in glassy silica ampoules often tend to yield oxosilicates as by-products. Thus, the two presented silicates Pr$_2$O[SiO$_4$] and Sm$_2$O[SiO$_4$] were also obtained from different reactions including the elemental lanthanoids, but with other target compounds. Both crystallize isostructurally to the Ln$_2$O[SiO$_4$] series adapting the known A-type structure.
Cationic group 14 element(II) centers can be used as ligands in Ni(0) complexes keeping its Lewis acidic reactivity while being coordinated to the Ni(0) center. By introduction of a chelating phosphine arm the back bonding from the metal center is minimized due to constrained binding leading to highly Lewis acidic Ge(II) and Sn(II) centers. This is a promising discovery for potential applications in catalysis or challenging bond activation due to possible metal ligand cooperation (MLC).
Copper(I)-based pillarplexes, supramolecular organometallic complexes (SOCs) with a tubular cavity and a high affinity for the incorporation of linear alkanes, are presented. These organometallic cavitands can incorporate diaminoalkanes and upon formation of a host–guest insertion complex and are readily transformed to [2]rotaxanes by amide formation in presence of a bulky benzoic anhydride. The structure of the assembly was elucidated by SC-XRD and is discussed along with its packing.
Coordination polymer [Cu(2,3-pdc)H2O]n was obtained by solvothermal synthesis in a Berghof BF100 pressure reactor using QUIN (quinolinic Acid) and Cu(HSO3)2 as substrates. The resulting compound crystallizes in triclinic system, in a space group of , with a = 7.434(3) Å, b = 7.523(4) Å, c = 7.881(3) Å, α = 62.68(5)o, β = 79.02(5)o, γ = 78.90(5)o, V = 381.5(3) Å3, Z = 2.
The reaction of CH3NH2 with CH3NH3PbI3 leads to the formation of a yellow viscous liquid and colorless crystals. Our group was able to identify these crystals as [Pb(CH3NH2)6]I2, the first homoleptic lead-ammine complex. We herein report on the findings of the interactions of CH3NH2 with BX2 and CH3NH3BX3 (B = Pb, Sn; X = I, Br, Cl).
The double perovskite series with the formula Sr2Fe1-xNixTeO6 (x = 0, 0.25, 0.50, 0.75, and 1) has been synthetized in polycrystalline form by a conventional solid-state reaction process by heating to 1300 K in air. Their crystal structures were probed by means of X-ray diffraction at room temperature. Rietveld analysis revealed that all the compositions crystallize in monoclinic space group I2/m.
Electron density studies on a recently published Cobalt Single-Molecule Magnet (SMM) were conducted to get a better insight in the origin of magnetical properties of this compound. The Electron density was obtained by X-ray diffraction and modelled with multipolar refinement.
While the electronic structure of SrO and SrTiO3 is sufficiently clarified in literature, there is a lack of information concerning the Ruddlesden-Popper (RP) phases. In this work density functional theory is used to compute the electronic structure for the homologous series with 𝑛 = 0 - 3, ∞. The according band structures are presented and effective masses are given for the complete system. In addition, the calculations are consulted to discuss the thermodynamical stability of the RP phases.
Macrocyclic host molecules are versatile building blocks in the supramolecular chemistry and crystal engineering. We report here an aqueous self-assembly driven by complementarity in charge and symmetry between two families of charged macrocyclic hosts - cationic pillar[n]pyridiniums and anionic p-sulfonatocalix[4]arene. The crystallization in gel and liquid-liquid diffusion have been used to obtain suitable crystals build from mixed macrocycles for single crystal X-ray diffraction analysis.
HoFeO3 is one of the most interesting representatives of the RFeO3 family with orthorhombic structure. We concentrated on the evolution of the magnetic order on Fe and Ho with external magnetic field applied along crystallographic c direction. Using the deflection and extrema points from different peaks the phase boundaries could be traced, resulting in a reach magnetic phase diagram with multiple phases.
On our poster we present the crystal structure and structure determination of Na7RbTl4, the first thernary phase in the ratio A:Tl 2:1. Na7RbTl4 yet is only the second known thallide which excusively contains isolated Tl48- Zintl anions beside the long-known Na2Tl reported by Hansen and Smith in 1967.During structure solution and refinement pseudomerohedral twinning was considered.
We report several novel hybrid halogenobismuthates, specifically chlorobismuthates and iodobismuthates, which were synthesized to find possible acentric candidates for use as non linear optical materials. The employed organic cations are dimethylpyridinium (DMP), 3-iodopropylammonium (3-IPA) and 1-phenethylammonium (1-PEA) in both R and S configurations, resulting in monoclinic (Cc and P21) and orthorhombic (P212121 and Pna21) compounds.
In this work, multicore iron oxide nanoparticles, in particular the intergrowth of individual cores within the particles, was studied by a combination of transmission electron microscopy and X-ray diffraction. The sizes of the nanoparticles and the individual cores were correlated with the crystallite size determined by X-ray diffraction. The effect of the crystallographic coherence on the crystallite size is discussed.
Role of lithium diffusion on thermal expansion of Li0.4WO3 bronze studied by neutron elastic and quasi-elastic scatterings
Red rod-shaped single crystals of Sm$_{7}$F$_{12}$Cl$_{2}$ (CSD-2126941) with a length up to 0.3 mm were obtained after heating up a mixture of Sm, SmF$_{3}$ and NaCl (as flux) in a sealed niobium capsule to 850 °C and cooling down the product with 5 °C/h after four days.
Sm$_{7}$F$_{12}$Cl$_{2}$ crystallizes in the Ba$_{7}$F$_{12}$Cl$_{2}$-type structure with a = 1004.52(7) pm, c = 394.75(3) pm and Z = 1 (space group: P-6) analogous to Eu$_{7}$F$_{12}$Cl$_{2}$.
Its about the Synthesis an characterisation of SmBi2O4Cl.
Stimulated Raman scattering (SRS) and Raman-induced four wave mixing (RFWM) processes in grown crystals of the orthorhombic nitrate alpha-KNO3 are presented. The investigation discovered three SRS-active modes which give rise to more than ten emission lines in the spectral range from UV to near IR.
Structural and spectroscopic properties of SnMBO4 (M = Al, Ga)
In the current contribution, a systematic ex-situ neutron powder diffraction study on differently electrochemical delithiated NCA cathode materials is presented. A set of structural parameters was obtained by using full-profile Rietveld refinement. Lithium occupations have been found linearly reflecting the increasing state-of-charge. In contrast, the refined occupations of transition metals do not change on the state-of-charge, indicating the absence of antisite defects in the NCA material.
Materials like Cu$_{2}$MnGeS$_{4}$ and Cu$_{2}$MnSnS$_{4}$ are promising candidates as absorber material in tandem solar cells. They show a wide bandgap in the range of 1.6-1.72 eV, while being made of non-toxic and earth abundant elements. Results of the chemical composition study in combination with structural characterization (XRD and neutron diffraction) as well as the optical bandgap evaluation from diffuse reflectance of the Cu$_{2}$Mn(Ge,Sn)S$_{4}$ mixed crystals will be presented.
Hafnium Zirconium Oxide HfxZr1-xO2 comprises a large variety of symmetrically related phases that were reported experimentally or theoretically. The symmetry reductions are hierarchically presented in a Bärnighausen-like tree that was extended for reconstructive transitions characterising severe atomic shifts. A method is presented explaining how to identify corresponding reflections of a structure before and after a phase transition.
Synthesis and characterization of mullite-type NdMnTiO5: Structural, spectroscopic, thermal and magnetic properties analyses
The presented work, shows the structure solution and refinement of PrCa4O[BO3]3 from single crystal X-ray diffraction data. A PrCa4O[BO3]3 single crystal was grown by the Czochralski method. The crystal structure was solved from single crystal X-ray diffraction data in the monoclinic crystal system with space group C1m1 (No. 8). The lattice parameters are a = 8.1293(6) Å, b = 16.062(1) Å, c = 3.6023(2) Å and β = 101.371(2)°. A disorder between Pr and Ca of up to 6.0% have been refined.
Despite being referred to as "chemical graveyard" [1] crystals may play an important role in synthesis routes which require a stereo-specificity which is only present in a crystal lattice due to the fixed arrangement of the reacting molecules. The reaction yields of chemical reactions initiated by light absorption may also be higher than that in solution since the reacting molecules are very close to each other in the crystal lattice.
Due to their biocompatibility and magnetic properties, iron oxide nanoparticles are especially interesting for applications such as targeted drug delivery and hyperthermia therapy. We studied the relationship between the composition of iron oxide particles and the exchange bias effect. The magnetic properties of the samples can be tuned by oxidation or reduction via different annealing procedures. These results provide important information for the manipulation of the exchange bias in oxide NPs.
Aus der Reihe der Dialuminate A6 [Al2Q6 ] (A=K, Rb, Cs; Q=S, Se, Te) konnten sechs bislang unbekannte Verbindungen dargestellt werden. Ihre Strukturen werden eingeordnet in die Strukturchemie der Dimetallate mit kantenverknüpften Tetraederdimeren und die Ergebnisse der Bandstrukturrechnungen an Aluminaten werden vorgestellt.
Here, we demonstrate the use of AlphaFold on proteins from SARS-CoV-2. While the solved structures only cover a part of the viral genome we have plenty of annotated protein-coding genes, which structures can now be predicted computationally. We discuss both the benefits as well as the potential shortcomings of these predictions and show how they can be combined with information from other tools and experimentally determined structures to get new insights into the structural biology of the virus.
Our work focuses on the identification of novel therapeutics against SARS-CoV-2. Using a HT screening approach, compound libraries of approved drugs are used for the discovery of inhibitors for enzymes of the coronavirus replication-transcription complex, followed by the structural determination of the enzyme-inhibitor complexes, revealing their binding mode. This approach is cost efficient, HT compatible, allowing direct identification of potent inhibitors and optimization of beamtime use.
Structure-based design of new inhibitors of the SARS-CoV-2 main protease (Mpro) is discussed and corresponding crystal structures are described. Pharmacokinetics of frontrunner inhibitors are presented. The evolution of the Mpro from the original Wuhan strain via the Alpha, Beta, Delta, and Omicron variants of concern is followed in terms of three-dimensional (crystal) structures, enzymatic activities, and inhibitor potencies.
During this decade, protein crystallography has immensely increased the speed of structure determination, allowing now using this high resolution technology for experimental fragment screening and hit optimization. At the same time, family wide structural genomics efforts elucidated molecular details of entire protein families including the main drug target families such as protein kinases, phosphatases, proteases and others.
Various spin-canting sublattices at three unique Mn sites in the ferrimagnetic phase (C2'/c') of Mn2+5(PO4)2(PO3(OH))2(HOH)4 (C2/c) explains a weak ferromagnetism. Below the Curie temperature (6.17 k), magnetic spin-canting reorientations continuously proceed. This vivid spin dynamic system could be confirmed by ac magnetic susceptibility under oscillating magnetic within a frequency window of 10-10000 Hz. Details of these vital magnetic spin dynamics are reported at the meeting DGK 2022.
The existence of a vortex phase with non-trivial topological properties in an antiferromagnetic incommensurate magnet Ba₂CuGe₂O₇ has been verified, by means of neutron scattering and bulk measurements of specific heat and AC susceptibility. Despite lacking evidence of any signature of a phase transition in the bulk magnetisation and specific heat measurements, hints towards the presence of a vortex phase were found in the neutron scattering data.
Oleic acid-coated nanoparticles were prepared by coprecipitation method in one step. The cationic distribution among tetrahedral and octahedral sites of Co2+ and Fe3+ was determined by Rietveld method and the inversion degree represented by concentration of Co2+ in tetrahedral site was found to be 0.4. Magnetic characterization at theree different temperature revealed the super-paramagnetic behaviour.
Small-angle neutron scattering is used in combination with transport measurements to study the current-induced effects on the morphology of the intermediate mixed state in the intertype superconductor niobium. We report the robust self-organisation of the vortex lattice domains to elongated parallel stripes perpendicular to the applied current in a steady-state. Our experimental results are supported by theoretical calculations, which highlight important details of the vortex matter evolution.
In a previous series of experiments to decipher the number of existing ternary phases in K2O-CaO-SiO2 system, we proved the presence of K4CaSi6O15 as a stable compound at ambient conditions and solved its crystal structure. Recently, we further revealed that the compound undergoes two structural phase transitions with increasing temperature.Diffraction data collected between 462 K and 666 K show satellite reflections, which suggest that the phase is 3+2-dimensionally modulated.
Nanoparticles of noble metals are of great importance as they present diverse applications in several fields. However, bimetallic nanoparticles of noble metals are showing an advantage over monometallic ones, especially those with defined shape and size due to their improved properties. In this work, core-shell nanocubes consisting of two coin metals, e.g. silver (Ag) and gold (Au), were synthesized and fully characterized with spectroscopic, analytical and microscopic techniques.
Here we present a high energy X-ray total scattering study of aqueous IONP dispersions. Pushing the boundaries of detection efficiencies for diminutive signals from weak scatterers (sub 1% of total scattered intensity), hydration shell signals are retrieved by careful double-difference pair distribution function analysis of the total scattering data from the dispersion minus bulk water minus the IONP powder. Impact of different factors like particle size and ligand decoration were investigated.
Bimetallic nanoparticles offer a new degree of freedom to vary the particle characteristics by blending two metals in one particle. We have prepared series of monodisperse nanoalloys over the entire composition range and analyzed their structure using a wide range of methods. X-ray diffraction as well as electron microscopic and spectroscopic techniques were employed to understand the structure of nanoparticles.
We have established a novel method for the self-organization of biomolecular building blocks and nanoparticles. Here, protein containers, engineered with opposite surface charge, are used as an atomically precise ligand shell for the assembly of inorganic nanoparticles. The assembly of protein-nanoparticle composites through supramolecular interactions yields highly ordered nanoparticle superlattices with unprecedented precision.
Spherical PVP-coated Ag (10 nm) and Pt (3 nm) NPs were wet-chemically synthesized and mixed as aqueous dispersion with different mass ratios of Ag:Pt. It was shown that the dissolution of Ag NPs was strongly enhanced by the presence of Pt NPs in chloride-containing aqueous dispersion. This behavior was confirmed by PXRD and TEM (Fig. 1). At the same time, only a slow dissolution of Ag NPs in presence of Pt NPs was detected in water or ammonium acetate or phosphate-buffered saline solutions.
β-Al4.5FeSi frequently occurs in recycled Al-Si alloys. Unsolved issues of the atomic structure obstructs its analysis in the materials. New crystal structures of β-Al4.5FeSi including polytype formation and ordering of Al and Si atoms are presented. Furthermore, the present study reconciles experimental results, own and from literature, additionally to evidence from DFT calculations to conclude on unsolved issues of the structure interpretation with consequences at all microstructural levels.
In this work we shed the light on the mechanism of mesocrystals formation. We use the process of gamma-radiation induced synthesis of CeO2 mesocrystals as a model reaction, and perform time dependent studies using combination of different techniques including energy-filtered electron radial distribution function analysis and in-situ TEM. We follow the reaction from the very early stages showing the role of intermediate amorphous phases at each stage. The work is published in Angewandte Chemie.
The crystal chemistry of AIBIIXO4 (AI = Alkali ion, BII = alkali-earth ion, X = P, V, As) is very rich and has been widely investigated. We have been investigated the crystal structures of several compositions within the AIBIIVO4 series (X = V). In this contribution, we present the crystal structure, rich polymorphism and re-entrant phase transition of NaSrPO4 as investigated by in-situ powder diffraction.
If the compound of interested is liquid under ambient conditions, conventional crystallization methods are not able to deliver suitable crystals for X-ray diffraction. In situ capillary crystallization is used for the crystallization of enantiopure liquids to determine the absolute configuration. The main advantages of the method are that only a small sample amount (~5 mg) is required and that there is no need to rely on reference substances to determine the absolute configuration.
The effect of step-wise thermally induced annealing on the mechanical properties (i.e., E Modulus and hardness), as well as on the short range order, determined by Raman and photoluminescence spectroscopy, of radiation-damaged pyrochlore (A2B2X6Y) will be presented. While, the structural amorphization and subsequent reorganization process can be described by means of percolation theory, the latter shows avalanche behavior.
Understanding how the CoV replication/transcription complex (RTC) works is central to design antiviral drug therapies as well as to the understanding of the emergence of variants. The SARS-CoV2 RTC is blatantly more 'active' than any other viral RdRp known. It possesses both unusually high nucleotide incorporation rates and high-error rates allowing facile insertion of mispaired nucleotides ('errors') but also nucleotide analogues used as antiviral drugs.