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

TL;DR

This paper predicts a new high-pressure ternary hydride Li$_2$SiH$_6$ with multiple stable phases, demonstrating potential for high-temperature superconductivity up to 56 K, advancing the search for room-temperature superconductors.

Contribution

The study introduces a novel stable ternary hydride Li$_2$SiH$_6$ with multiple phases and explores its superconducting properties under high pressure, which was not previously known.

Findings

Li$_2$SiH$_6$ is stable from ambient to 400 GPa.

The maximum $T_c$ reaches 56 K at 400 GPa.

Multiple stable phases with unique electronic and phonon properties.

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.