Superconducting H5S2 phase in sulfur hydrogen system under high pressure
Recently, hydrogen sulfide was experimentally found to show the high superconducting critical temperature (Tc) under high pressure. The superconducting Tc shows 30 70 K in pressure range of 100 170 GPa (low Tc phase) and increases to 203 K, which sets a record for the highest Tc in all materials, for the samples annealed by heating it to room temperature at pressures above 150 GPa (high Tc phase) Here we present a solid H5S2 phase predicted as the low Tc phase by the application of the genetic algorithm technique for crystal structure searching and first principles calculations to sulfur hydrogen system under high pressure. The H5S2 phase is thermodynamically stabilized at 110 GPa, in which asymmetric hydrogen bonds are formed between H2S and H3S molecules. Calculated Tc values show 50 70 K in pressure range of 100 150 GPa within the harmonic approximation, which can reproduce the experimentally observed low Tc phase. These findings give a new aspect of the excellent superconductivity in compressed sulfur hydrogen system.
Scientific reports