Structural phase transition of CdS microcrystals under high pressure

CdS microcrystals embedded in two kinds of matrices, SiO films and GeO2 gla sses, with various sizes have been studied by Raman scattering and optical absorption under high pressure. A structural phase transition of the CdS mi crocrystals from wurtzite to rock salt phase was observed at a pressure hig her than the bulk CdS transition pressure of 2.7 GPa. For CdS microcrystals embedded in SiO films, the phase transition pressure increased with decrea sing microcrystal size. However, the phase transition pressure of CdS micro crystals embedded in GeO2 glasses does not depend strongly on the microcrys tal size. These observations suggest that the matrix plays an important rol e on the phase stability of CdS microcrystals.