Phase Transitions and Superconductivity in Ternary Hydride Li${}_2$SiH${}_6$ at High Pressures

Abstract

We predicted a new ternary hydride Li${}_2$SiH${}_6$ at high pressures. A systematic structure search in Li${}_2$SiH${}_6$ compound reveals novel stable phases with intriguing electronic and phonon properties. It is found that Li${}_2$SiH${}_6$ is dynamically stable from ambient pressure up to 400 GPa with three novel phases: P312, P$\bar{3}$, and P$\bar{6}$2m. The calculation of electron-phonon coupling combined with Bardeen-Cooper-Schrieffer's argument indicates that this compound may be a candidate for high $T_c$ superconductors under high pressures. In particular, the maximum $T_c$ of $P\bar{6}2m$-Li${}_2$SiH${}_6$ at 400 GPa reaches 56 K. These findings may pave the way for obtaining room temperature superconductors in dense hydrogen-rich compounds.

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• Superconductive Sodalite-like Clathrate Hydrides MXH${}_{12}$ with Critical Temperatures of near 300 K under Pressures