Raman scattering study of pressure-induced phase transition in ZnA12(1-X)Ga2XS4

ZnAl_2(1-X)Ga_2XS₄ single crystals with the defect chalcopyrite (DC) structure have been studied by Raman spectroscopy under hydrostatic pressure up to 200 kbar. For X = 0.4 the pressure-induced changes in the Raman scattering (RS) spectra at 70 and 120 kbar were explained on the basis of two stages of order-disorder transition in the cation sublattice. The irreversible disappearance of RS signal at pressures above 170 kbar was attributed to a phase transition to Raman-inactive rocksalt-type structure. For low values of X (X = 0.1 ÷ 0.2) a new phase was observed which coexisted with the DC structure in the interval 70 ÷ 150 kbar.