Pressure-temperature phase diagram of solid hydrogen sulfide determined by Raman spectroscopy.

With Raman spectroscopy, the pressure-temperature (P-T) phase diagram for solid hydrogen sulfide has been determined at high pressures up to about 20 GPa and at low temperatures down to 30 K. The triple point between the II, III, and IV phases of solid ${\mathrm{H}}_{2}$S exists at about 3.1 GPa and 153 K. Phase IV is stable in the wide P-T region, and the phase diagram of solid ${\mathrm{H}}_{2}$S is simple in comparison with that of ${\mathrm{H}}_{2}$O ice, which has many high-pressure phases.