High-pressure phase of solid hydrogen sulfide

Abstract

Hydrogen-bonded molecular solid ${\mathrm{H}}_{2}$S has been studied up to 42 GPa to search for a high-pressure phase by x-ray diffraction at room temperature. New diffraction peaks appeared above 27 GPa, which indicates a transition from phase IV to another phase, phase V. A color change from a thin yellow to black was observed at this transition, which indicates a large decrease of the energy gap at the IV-V phase transition. Phase V may be metallic in the region of 27-42 GPa.