High-pressure investigations on the isostructural phase transition and metallization in realgar with diamond anvil cells

The high-pressure structural, vibrational and electrical properties for realgar were investigated by in-situ Raman scattering and electrical conductivity experiments combined with first-principle calculations up to ~30.8 GPa. It was verified that realgar underwent an isostructural phase transition at ~6.3 GPa and a metallization at a higher pressure of ~23.5 GPa. The isostructural phase transition was well evidenced by the obvious variations of Raman peaks, electrical conductivity, crystal parameters and the As-S bond length. The phase transition of metallization was in closely associated with the closure of bandgap rather than caused by the structural phase transition. And furthermore, the metallic realgar exhibited a relatively low compressibility with the unit cell volume V₀=718.1.4 ų and bulk modulus B₀=36.1 GPa.