Ternary superconducting cophosphorus hydrides stabilized via lithium

Inspired by the diverse properties of sulfur hydrides and phosphorus hydrides, we combine first-principles calculations with structure prediction to search for stable structures of Li‑P‑H ternary compounds at high pressures with the aim of finding novel superconductors. It is found that phosphorus hydrides can be stabilized under pressure via additional doped lithium. Four stable stoichiometries LiPH₃, LiPH₄, LiPH₆, and LiPH₇ are uncovered in the pressure range of 100–300 GPa. Notably, we find an atomic LiPH₆ with Pm3¯ symmetry which is predicted to be a potential high-temperature superconductor with a T_c value of 150–167 K at 200 GPa and the T_c decreases upon compression. All the predicted stable ternary hydrides contain the P–H covalent frameworks with ionic lithium staying beside, but not for Pm3¯-LiPH₆. We proposed a possible synthesis route for ternary lithium phosphorus hydrides: LiP + H₂ → LiPH_n, which could provide helpful and clear guidance to further experimental studies. Our work may provide some advice on further investigations on ternary superconductive hydrides at high pressure.