Li-Y-H三元氢化物的结构和稳定性研究

Structure and stability of possible new Li-Y-H ternary hydrides

本文基于粒子群优化算法的结构预测方法结合第一性原理计算,研究了LiYH_(4),Li_(2)YH_(5)和Li_(3)YH_(6)在0-300 GPa压力范围内的晶体结构、电子结构、热力学和动力学稳定性.研究结果表明LiYH4-P4/nmm,Li_(2)YH_(5)-I4/mmm和Li_(3)YH_(6)-P4/nmm结构可分别在169-221 GPa,141-300 GPa和166-300 GPa压力范围内由LiH和YH3按一定配比加压合成.富氢化合物的超导电性研究成为近年来高温超导体研究领域的热点,该研究结果有希望为Li-Y-H三元体系氢化物的超导电性研究及实验合成提供数据支撑.

The research on the superconductivity of hydrogen-rich compounds has become a hot research topic in the field of high-temperature superconductors in recent years and yttrium hydride YH9+x has been experimentally confirmed to have high temperature superconductivity(near room temperature(Tc=262 K)),following behind the research of H3S(Tc=200 K)and LaH_(10)(Tc=260 K).The theoretical study of binary hydrogen-rich systems is relatively mature,while the structural characteristics and superconductivity of ternary or quaternary hydrogen-rich compounds are still under exploration.In this paper,nLiH+YH3→LinYHn+3(n=1-3)is the synthesis way to explore the stable configuration of ternary hydride LinYHn+3 in a pressure range of 0-300 GPa.The crystal structure,electronic structure,thermodynamic and kinetic stability of LiYH4,Li2YH5 and Li3YH6 in the pressure range of 0-300 GPa are studied based on the structure prediction by particle swarm optimization algorithm and first-principles calculation.The CALYPSO method is used to search for 1-4 times molecular formula structures for Li-Y-H ternary systems with different stoichiometric ratios in the pressure range of 0-300 GPa in steps of 50 GPa.The results show that LiYH4-P4/nmm,Li2YH5-I4/mmm,and Li3YH6-P4/nmm can be respectively synthesized with a certain ratio between LiH and YH3 respectively in a pressure range of 169-221 GPa,141-300 GPa and 166-300 GPa.The Li2YH5 has the lowest stable pressure and widest range which can be the possible choice in experiment.The results can provide the data support for the superconductivity research and experimental synthesis of hydrides in Li-Y-H ternary system.