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Accessing hydrogen-rich ternary hydrides at gigapascal pressures: in situ PXRD studies in a large volume press

by Dr Kristina Spektor (DESY/Leipzig University)


Hydrides are an important and widely studied class of inorganic materials, to a large degree due to their hydrogen storage potential. In addition, hydrides can display a spectacular array of physical properties, including superconductivity, due to the unique bonding properties of the hydrogen anion. In the recent years, a growing number of experimental and computational studies have proved extreme p, T to be an efficient tool for accessing novel hydrides with increased hydrogen content. Discovery of near-RT superconducting H3S in 2015 stimulated the research efforts, revealing novel binary superhydrides with high Tc. The latter, however, require pressures >100 GPa to obtain and are not recoverable to ambient conditions. On the contrary, ternary hydrides can be produced at pressures < 10 GPa in a large volume press (LVP) and recovered at ambient, while possibly retaining superconductive properties. Combining synthesis in an LVP with in situ synchrotron X-ray diffraction allows to search for new hydride representatives and provides valuable insight into their formation and p, T phase behaviour. In this talk the recent in situ studies of A-T-H systems (A = Group I/II metal, T = transition metal) conducted at ESRF at p, T up to 12 GPa and 600 °C  will be shown, followed by presenting our current project at P61b beamline, PETRA III, with the focus on the recoverable potentially superconducting ternary hydrides.