Structural Diversity and Superconductivity in S-P-H Ternary Hydrides Under Pressure

Abstract

Evolutionary structure searches revealed a plethora of stable and low-enthalpy metastable phases in the S-P-H ternary phase diagram under pressure. A wide variety of crystalline structure types were uncovered ranging from those possessing one-dimensional chains, twodimensional sheets based on S-H or S-P-H square lattices as well as S-H or P-H honeycombs, and cage-like structures. Some of the cage-like structures could be derived from doping the high-pressure high-temperature superconducting Im 3m H 3 S phase with phosphorous. Most of the discovered compounds were metallic, however those derived from Im 3m H 3 S lattices with low levels of P-doping were predicted to possess the highest superconducting critical temperatures (T c s). The propensity for phosphorous to assume octahedral coordination, as well as the similar radii of sulfur and phosphorous are key to maintaining a high density of states at the Fermi level in Im 3m S 0.875 P 0.125 H 3 , whose T c was estimated to be similar to that of H 3 S at 200 GPa.