GeTe that exhibits a strong anharmonicity and a ferroelectric phase transition between the rhombohedral and cubic structures has emerged as one of the leading thermoelectric materials. Herein, combining molecular dynamics simulations and inelastic neutron scattering measurements, the lattice dynamics in GeTe have been investigated to reveal the soft-mode mechanisms across the phase transition.
Enhanced Reducibility of the Ceria-Tin Oxide Solid Solution Modifies the CO Oxidation Mechanism at the Platinum-Oxide Interface
The introduction of tin into ceria strongly influences its reducibility. In turn, the reaction mechanism towards the oxidation of carbon monoxide changes: the oxidation rate increases, the apparent activation energy decreases and the reaction order in oxygen increases.
Full-field X-ray absorption tomography reveals the chemical structure of defects in metal-organic frameworks
Cryo-full-field XANES computed tomography was used to visualize the presence and distribution of a second coordination polymer of reduced copper coordination within defect-engineered HKUST-1 MOF crystals. Observations encourage a revisitation of the structure-property relationships of defect-engineered MOFs.
The entire study is an investigation into the self-similarity behavior  of first and second order statistical quantities derived from a large-scale jet flow taken from one of the experiments in the PANDA facility using the Proper Orthogonal Decomposition (POD).
What is presented, are the merits, the potential and the characteristics of the corresponding underlying POD analysis. Proper Orthogonal Decomposition (POD) is a mathematical framework to extract large-scale structures which are otherwise eventually masked by the complexity of the fully turbulent flow; example: the meandering of a jet which is not so obvious for the original data.
Prof Philip Willmott, the author of the book 'Introduction to Synchrotron Radiation: techniques and applications' (second edition, John Wiley & Sons, Chichester, 2019. ISBN: 9781119280392), makes the scripts for the simulations and animations available to the public.
Correlation between Oxygen Vacancies and Oxygen Evolution Reaction Activity for a Model Electrode: PrBaCo2O5+δ
The role of the oxygen stoichiometry of perovskite catalysts in the oxygen evolution reaction (OER) is systematically studied in the PrBaCo2O5+δ family. The reduced number of physical/chemical variables combined with in-depth characterizations such as neutron diffraction, O K-edge X-ray absorption spectroscopy(XAS), electron energy loss spectroscopy (EELS), magnetization and scanning transmission electron microscopy (STEM) studies, helps investigating the complex correlation between OER activity and a single perovskite property, such as the oxygen content. Larger amount of oxygen vacancies appears to facilitate the OER, possibly contributing to the mechanism involving the oxidation of lattice oxygen, i.e., the lattice oxygen evolution reaction (LOER). Furthermore, not only the number of vacancies but also their local arrangement in the perovskite lattice influences the OER activity, with a clear drop for the more stable, ordered stoichiometry.
Pooja Thakkar received the Shoulders-Gray-Spindt award at the 34th Vacuum Nanoelectronics Conference for her paper "Voltage-controlled three-electron-beam interference by a three-element Boersch phase shifter with top and bottom shielding electrodes"
Imaging strain in crystalline materials with high resolution can be a challenging task. Researchers demonstrate an original use of X-ray ptychography for this purpose: ptychographic topography.
Magnetic anisotropy is anticipated to govern the formation of exotic spin textures reported recently in cubic chiral magnets, like low-temperature tilted conical and skyrmion lattice (SkL) states and metastable SkLs with various lattice geometry. Motivated by these findings, we quantified the cubic anisotropy in a series of CoZnMn-type cubic chiral magnets. We found that the strength of anisotropy is highly enhanced towards low temperatures. Moreover, not only the magnitude but also the character of cubic anisotropy drastically varies upon changing the Co/Mn ratio.
The rare earth nickelates RNiO3 are metallic at high temperatures and insulating and magnetically ordered at low temperatures. The low temperature phase has been predicted to be type II multiferroic, i.e., ferroelectric and magnetic order are coupled and occur simultaneously. Confirmation of those ideas has been inhibited by the absence of experimental data on single crystals. Here we report on Raman spectroscopic data of RNiO3 single crystals (R = Y, Er, Ho, Dy, Sm, Nd) for temperatures between 10 and 1000 K. Entering the magnetically ordered phase we observe the appearance of a large number of additional vibrational modes, implying a breaking of inversion symmetry expected for multiferroic order.