TY  - JOUR
AU  - Hu, Huixin
AU  - Kuzovnikov, Mikhail A.
AU  - Shuttleworth, Hannah A.
AU  - Marqueño, Tomas
AU  - Yan, Jinwei
AU  - Osmond, Israel
AU  - Gorelli, Federico A.
AU  - Gregoryanz, Eugene
AU  - Dalladay-Simpson, Philip
AU  - Ackland, Graeme J.
AU  - Peña-Alvarez, Miriam
AU  - Howie, Ross
TI  - Unexpected compound reformation in the dense selenium-hydrogen system
JO  - Communications materials
VL  - 6
IS  - 1
SN  - 2662-4443
CY  - London
PB  - Springer Nature
M1  - PUBDB-2025-03882
SP  - 193
PY  - 2025
AB  - The H<sub>2</sub>Se molecule and the van der Waals compound (H<sub>2</sub>Se)<sub>2</sub>H<sub>2</sub> are both unstable upon room temperature compression, dissociating into their constituent elements above 22 GPa. Through a series of high pressure-high temperature diamond anvil cell experiments, we report the unexpected formation of a novel compound, SeH<sub>2</sub>(H<sub>2</sub>)<sub>2</sub> at pressures above 94 GPa. X-ray diffraction reveals the metallic sublattice to adopt a tetragonal (I4<sub>1</sub>/amd) structure with density functional theory calculations finding a small distortion due to the orientation of H<sub>2</sub> molecules. The structure comprises of a network of zig-zag H-Se chains with quasi-molecular H<sub>2</sub> molecular units hosted in the prismatic Se interstices. Electrical resistance measurements demonstrate that SeH<sub>2</sub>(H<sub>2</sub>)<sub>2</sub> is non-metallic up to pressures of 148 GPa. Investigations into the Te-H system up to pressures of 165 GPa and 2000 K yielded no compound formation. The combined results suggest that the high pressure phase behavior of each chalcogen hydride is unique and more complex than previously thought. 
LB  - PUB:(DE-HGF)16
DO  - DOI:10.1038/s43246-025-00899-9
UR  - https://bib-pubdb1.desy.de/record/637656
ER  -