Synthesis of New Hydrides in Mg-Y Systems by Using High Pressure

Abstract

A new hydride in the MgH₂–YH₃ system was found by using a high pressure of 5 GPa, and their crystal structure, thermal stability and hydrogen content were studied. The high-pressure synthesis was carried out at 1073 K for 2 h under 5 GPa by using an anvil-type apparatus. In the MgH₂–xat%YH₃ system (x=33–100), novel hydride was synthesized near x=67 (MgY₂H_y). This phase exhibited a FCC-type structure with a cell parameter of a=0.516 nm. This high-pressure phase was dehydrogenated at about 600 K under an Ar atmosphere of 0.05 MPa, and the FCC structure was maintained after dehydrogenation. The amount of hydrogen desorbed at about 600 K was 1.4 mass%.