Structural phase transition of CdS microcrystals under high pressure

CdS microcrystals embedded in two kinds of matrices, SiO films and GeO2 glasses, with various sizes have been studied by Raman scattering and optical absorption under high pressure. A structural phase transition of the CdS microcrystals from wurtzite to rock salt phase was observed at a pressure higher than the bulk CdS transition pressure of 2.7 GPa. For CdS microcrystals embedded in SiO films, the phase transition pressure increased with decreasing microcrystal size. However, the phase transition pressure of CdS microcrystals embedded in GeO2 glasses does not depend strongly on the microcrystal size. These observations suggest that the matrix plays an important role on the phase stability of CdS microcrystals.