Syntheses of Novel Hydrides Containing Light Elements under High Pressure and High Temperature

This paper describes high-pressure synthetic studies on novel hydrides. High-pressure hydrogenation experiments are carried out using a cubic-type multi-anvil apparatus. In-situ synchrotron radiation X-ray diffraction measurements are effectively used to explore synthetic conditions, to investigate the reaction mechanisms, and to characterize the thermodynamic stabilities of the obtained hydrides. Theoretical calculations based on first-principles calculations enable us to predict the thermal stability and crystal structure of the target hydrides before the high-pressure experiments, which leads to the rapid discovery of the novel hydrides. Lithium-containing hydrides, YLiFeH6, LiNiH3, Li4FeH6, and Li3AlFeH8 are synthesized. Syntheses of aluminum-based alloys hydrides, Al2CuH and Al3FeH4 under high-pressure are also described. These results demonstrate that the high-pressure technique is useful for discovering novel hydrides.