The structure of SiO2 sol-gel glass doped with Cu and annealed in oxidizing and reducing atmospheres

SiO2 glass in the form of powder and thin films was obtained by the sol-gel process involving the solidification (gelatinization) of a solution. The d oping impurity was introduced in the solution. The samples obtained were he at-treated in oxidizing or reducing atmospheres. The structure of the glass with different amounts of the doping impurity and the positions of the dop ing atoms were studied with x-ray diffraction, infrared light absorption, a nd the spin resonance techniques. It was found that the introduced copper e xists in the form of separate atoms (in interstitial or substitutional site s) or within the colloidal metallic or metal oxide particles, depending on the impurity concentration, the kind of atmosphere and the temperature duri ng heat treatment. The results obtained are treated on the basis of the mod el assuming that the glass structure resembles that of P-cristobalite, and the elastic waves in the O-Si-O chains composing this structure are respons ible for the infrared absorption in the 1000-1300 cm(-1) region.