Pressure‐induced lattice‐dynamical stability and superconductivity of ternary pentahydride MgNiH ₅

Abstract

Summary We predict the existence of ternary pentahydride MgNiH5, adopting a hexagonal structure with a space group P63/mmc, at high pressure. Typically, the clarity of structural‐phase stability could be demonstrated by thermodynamical and dynamical stabilities. Herein, we introduce a critical temperature (Tc) superconductivity of the ternary pentahydride, based on the isotropic Éliashberg equation. The Tc is estimated by directly solving the Allen‐Dynes equation, with a remarkable value of Tc at 25.6 K. Under the compressing pressure from 100 to 300 GPa, the Tc of MgNiH5 is determined by means of the phonon‐mediated superconductivity, arising particularly from a magnitude of partial electron‐phonon coupling. Our calculation paves the way for achieving a ratio and a Tc superconductivity in the family of ternary polyhydride.