High-temperature superconducting ternary Li-R-H superhydrides at high pressures (R = Sc, Y, La)

Compressed clathrate superhydrides have been the most promising candidates for room-temperature superconductors since the theory-oriented findings of CaH6, YH9, LaH10 et. al., where the hydrogen clathrate framework was believed to play a critical role in improving superconductivity. Recently, a ternary superhydride of Li2MgH16 was predicted to be a "hot" superconductor with a theoretical T-c value up to 473 K at 250 GPa, although it exhibits the metastable feature under high pressure. With the aim of seeking thermodynamically stable ternary clathrate superhydrides, by exploring the high-pressure phase diagram of the Li-R-H (R = Sc, Y, and La) systems at 300 GPa, we identified several thermodynamically ternary superhydrides with high-temperature superconductivity. Among these predicted stable structures, as a result of extensive simulations, clathrate structured Li2YH17 and Li2LaH17 are predicted to be high-temperature superconductors with a superconducting critical temperature (T-c) up to 108 and 156 K, at 200 and 160 GPa, respectively. Interestingly, a superhydride, Immm-Li2ScH20, with mixed molecular and atomic hydrogen, is predicted to possess a high T-c of 242 K at 300 GPa. The present results may stimulate the future experiment for the investigation of structural, electronic, and superconducting properties of metal-doped rare-earth superhydrides, which thus help the further design and discovery of superconducting clathrate superhydrides.