High pressure synthesis of hydride in Li-Y system

High-pressure synthesis has been widely used for exploration of novel materials. In this study, Li-Y hydrides were explored under GPa-order pressure by using a cubic-anvil-type apparatus. Unfortunately, a novel hydride in Li-Y system was not synthesizedin this study, but it is found that 10 at% addition of Li can stabilize FCC-YH₃ high pressure phase even under ambient pressure. The Li added FCC-YH₃ have a CeH.₃ type structure judging from the results of XRD and raman spectrometry and its lattice constant was estimated to be 0.52666(1) nm. Total hydrogen content of the hydride was estimated to be 3.52 mass%. This hydride was partially dehydrogenated at 575 K with decreasing its lattice constant down to 0.5206( 1) nm. Then, the sample could absorb hydrogen again under 5 MPa-H₂ at 623 K. Hydrogenation enthalpy of the hydride was estimated from endothermic peak to \δH\ = 29.2kJ/mol-H and this value is lower than that of YH₃ ambient pressure phase.