Synthesis of novel YFe2H(x>10) compounds up to 100 GPa: a possibility to recover a high content H-storage material at ambient pressure

Hydrogen uptake by a metal drastically increases under high hydrogen pressure. New polyhydrides compounds are interesting as H-storage materials and hold great promise as high temperature superconductors. Pressures in the 100 GPa range have to be applied and unfortunately none of these novel Metal-Hydrogen compounds is metastable at ambient pressure. Hence, there is now great interest to form such H-rich compounds at high pressure and to recover them at ambient pressure by adding a third element. The aim of this proposal is to show that searching for ternary hydrides is indeed a good strategy. We performed ab-initio calculations showing that YFe2H10 is predicted to form at about 20 GPa and that it could be recovered metastable at ambient pressure. YFe2 alloy will be compressed in excess hydrogen and the formation of YFe2Hx compounds will be characterized by a detailed structural study at various pressures. The metastability of the YFe2H at ambient pressure will be investigated.