Ternary superconducting titanium hydrides stabilized via lithium

Recently, the search for high temperature superconducting hydrides has become a hot topic. In this work, we employed genetic algorithm (GA) combined with density functional theory (DFT) calculations to explore the structures and superconductivity of the ternary hydrides LiTiHn (n = 1-10) within the pressure range of 50-200 GPa. Two stable stoichiometric ratios were discovered within this pressure range, namely LiTiH4 and LiTiH6. For P-6m2 LiTiH4, Ti, Li and H atoms are arranged alternately in layers, while Ti and H atoms form a six membered ring. The low-enthalpy phases R-3m and P4/mmm LiTiH6 exhibit metallic properties, with R-3m LiTiH6 containing TiH14 units presenting a polyhedron and P4/mmm LiTiH6 containing TiH8 units presenting a cube. They are dynamically stable at 50 GPa and 100 GPa, respectively. The predicted Tc value is 79 K for R-3m LiTiH6 at 50 GPa, and 58 K for P4/mmm LiTiH6 at 100 GPa. These results may provide some guidance for the design of high temperature superconductors.