2025/05/22 by Caussé, M., Toraille, L., Geneste, G. +1 · 1 citation
#FOS: Physical sciences #Materials Science (cond-mat.mtrl-sci) #Other Condensed Matter (cond-mat.other) #Superconductivity (cond-mat.supr-con)
paper · doi:10.48550/arxiv.2505.16799
Reaching pressures in the 100 GPa range enables the synthesis of hydrogen-rich compounds, with nontraditional H stoichiometries and H sublattices, called superhydrides. Record-breaking superconductivity temperature in some superhydrides have attracted great interest. A crucial next step is to stabilize superhydrides outside of high-pressure environments, leading to a search beyond binary hydrides to ternary hydrides. Here, we report the synthesis of Y3Fe4H20 at pressures starting at 60 GPa by compressing an hydrogenated Y-Fe compound, embedded in hydrogen in a laser-heated diamond anvil cell. Single-crystal X-ray diffraction allowed us to resolve the Y3Fe4 lattice skeleton, and a constrained ab initio structural search was used to position the hydrogen atoms. FeH8 cubic molecular units form building blocks which are connected edge-to-edge by sharing two hydrogen atoms, creating a framework that hosts Y cations. Remarkably, Y3Fe4H20 maintains its structure through decompression, making it the first superhydride recovered metastable under ambient conditions.