Pressure-induced superconducting CS2H10 with an H3S framework

Abstract

The discovery of the high-temperature superconducting state in the compounds of hydrogen, carbon and sulfur with a critical temperature (T_c) of 288 K at high pressure is an important milestone towards room-temperature superconductors. Here, we have extensively investigated the high-pressure phases of CS₂H₁₀, and found four phases Cmc2₁, P3m1, Pm1 and Pm. Among them, P3m1 can be dynamically stable at a pressure as low as 50 GPa, and Cmc2₁ has a high T_c of 155 K at 150 GPa. Both Cmc2₁ and P3m1 are host–guest hydrides, in which CH₄ molecules are inserted into Imm-H₃S and R3m-H₃S sublattices, respectively. Their T_c is dominated by the H₃S lattice inside. The insertion of CH₄ molecules greatly reduces the pressure required for the stability of the original H₃S lattice, but it has a negative impact on superconductivity which cannot be ignored. By studying the effect of CH₄ insertion in the H₃S lattice, we can design hydrides with a T_c close to that of H₃S and a greatly reduced pressure required for stability.