THE PREPARATION OF CDS PARTICLES IN SILICA GLASSES BY A SOL-GEL METHOD

The sol-gel process has been successfully applied to the preparation of a small-particle-size CdS-doped silica matrix with a significant quantum size effect. Transparent and colorless gels were prepared through the hydrolysis of a complex solution of Si(OC2H5)4, (CH3)(2)SO, and Cd(CH3COO)(2) . 2H(2)O. These gels were heated at 350, 500, 750, and 1000 degrees C to form fine, hexagonal, CdS-microcrystal-doped glasses. The thermal treatments of samples were established by TDA/TGA analysis. Structural evolution of alkoxide silica during densification was followed by infrared spectroscopy. Samples were characterized using X-ray diffraction. The absorption spectra have also been measured and indicate the potential application of this material in optical devices. A simple quantum mechanical model has been used to calculate the particle size from the absorption onset measured for CdS in the SiO2 matrix. The result is interpreted in terms of a quantum confinement effect of small crystal size. (C) 1995 Academic Press, Inc.