Stable structures and superconducting properties of Ca–La–H compounds under pressure

Abstract

Abstract The calcium hydrides and lanthanum hydrides under high pressures have been reported to have good superconducting properties with high-T C. In this work, the structures and superconductivities of Ca–La–H ternary hydrides have been studied by genetic algorithm and density functional theory calculations. Our results show that at the pressure range of 100–300 GPa, the most stable structure of CaLaH12 has a Cmmm symmetry, in which there is a H24 hydrogen cage. It can be expected to have high possibility to be synthesized due to its large stability. Furthermore, the predicted T C of the Cmmm-CaLaH12 structure is about 140 K at 150 GPa, and when the pressure decreases to 30 GPa, the CaLaH12 structure with a C2/m symmetry has a predicted T C of about 49 K. The CaLaH12 is suggested to be a stable good superconductor with large stability and performs well at relatively low pressures.