CdS microcrystal-doped silica glass prepared by the sol-gel process

Glass of composition of 4.4CdO·95.6SiO₂ was prepared by the sol-gel process from Si(OC₂H₅)₄ and Cd(CH₃COO)₂·2H₂O. CdS crystals were precipitated by exposing the glass of H₂S gas, which were identified with hexagonal würtzite CdS crystals. From the X-ray diffraction analyses and transmission electron micrographs, these crystals were 2 to 6 nm in diameter. In the optical absorption spectra, the absorption edge exhibited a blue shift compared to that of the bulk CdS and its energy shift was reciprocally proportional to the square of the crystal size. Thus the quantum size effect could be found for the glass containing CdS prepared by the sol-gel process.