Abstract
The effect of pressure on the structural, vibrational, and optical properties of lead thiogallate, PbGa(2)S(4), crystallizing under room conditions in the orthorhombic EuGa(2)S(4)-type structure (space group Fddd), is investigated. The results from X-ray diffraction, Raman scattering, and optical-absorption measurements at a high pressure beyond 20 GPa are reported and compared not only to ab initio calculations, but also to the related compounds α'-Ga(2)S(3), CdGa(2)S(4), and HgGa(2)S(4). Evidence of a partially reversible pressure-induced decomposition of PbGa(2)S(4) into a mixture of Pb(6)Ga(10)S(21) and Ga(2)S(3) above 15 GPa is reported. Thus, our measurements and calculations show a route for the high-pressure synthesis of Pb(6)Ga(10)S(21), which is isostructural to the stable Pb(6)In(10)S(21) compound at room pressure.