$A_2B_2O_7$ oxides gathered considerable attention due to many complex and exotic (ground) states observed or theoretically predicted, e.g., spin liquid, spin ice, topological insulator or Weyl semimetal [1,2]. Geometrical frustration of magnetic moments, responsible for these states, is defined very well in $A_2Ir_2O_7$ iridates (with A being the rare earth) since they crystallize in the...
With increasing share of energy generation from renewables, intermittent electrical energy storage is gaining significance. Sodium-ion batteries (SIB) are currently developed and commercialized as cost-effective complementary technology to today’s Lithium-ion batteries (LIB). For SIBs, P2-type layered oxides are considered amongst the most attractive cathode active materials.
In this work,...
The gradual ferromagnetic spin reorientation in the hcp phase of cobalt between 230 °C and 330 °C reported for a Co single crystal [1] suggests that this phase cannot have a hexagonal symmetry [2,3]. This hypothesis is verified positively by synchrotron radiation diffraction (MSPD@ALBA) and neutron diffraction (SPODI@MLZ and D2B@ILL) on the powder of cobalt [3]. The analysis of diffraction...
We present neutron scattering data on the hexagonal rare-earth diboride ErB$_2$. ErB$_2$ orders magnetically below T$_c$ = 14 K, where the magnetocrystalline anisotropy shows strong easy-plane characteristics, as established from measurements of the specific heat, ac susceptibility, magnetisation and electrical transport.
In order to investigate the magnetic structure we performed...
Enzymes are a sub class of proteins which act as natural catalysts and reduce the activation energy of chemical reactions necessary to keep up the metabolism of life. This renders enzymes important drug targets. To elucidate their structure is often the key to understand certain diseases. X-ray protein crystallography contributed by far the largest number of structures but methods like...
Hole doped transition metal oxides have been extensively investigated due to their many active degrees of freedom such as charge, spin, and orbital ordering. An interesting alternative to metal substitution in nickelates, e.g., RE2-xSrxNiO4, is achieved by oxygen doping, yielding RE2NiO4+d. The extra oxygen atoms have been evidenced to be mobile down to ambient temperature, adding an extra...
V-based oxides are attracting much interest as promising next-generation electrodes due to the vast resources in the Earth's crust, their unique open structures for fast diffusion with outstanding electrochemical properties and various oxidation redox couples. A recent review has debated if they “will become the future choice for ion-metal batteries”.[1] H2V3O8 allows reversible two-electron...
Increased attention to sodium-containing materials during the last years is caused by the rapid development of sodium-ion batteries (NIBs), which are considered as a potential successor for lithium-ion batteries (LIBs). Especially layered sodium oxides with transition metals have gained large interest due to their potential applicability as cathode materials. Similar to LiCoO2 in LIBs, NaCoO2...
Neutrons are a unique probe for non-destructive structural studies of energy materials, especially for the development of highly dense hydrogen stores. Thus, nano-porous materials have attracted great attention for gas storage, while the storage capacity still remains challenging. Here a magnesium borohydride framework with small pores was investigated and a unique partially negatively-charged...
