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The structure of SiO <inf>2</inf> sol-gel glass doped with Cu and annealed in oxidizing and reducing atmospheres

Abstract:

SiO 2 glass in the form of powder and thin films was obtained by the sol-gel process involving the solidification (gelatinization) of a solution. The doping impurity was introduced in the solution. The samples obtained were heat-treated in oxidizing or reducing atmospheres. The structure of the glass with different amounts of the doping impurity and the positions of the doping atoms were studied with x-ray diffraction, infrared light absorption, and the spin resonance techniques. It was found that the introduced copper exists in the form of separate atoms (in interstitial or substitutional sites) or within the colloidal metallic or metal oxide particles, depending on the impurity concentration, the kind of atmosphere and the temperature during heat treatment. The results obtained are treated on the basis of the model assuming that the glass structure resembles that of β-cristobalite, and the elastic waves in the O-Si-O chains composing this structure are responsible for the infrared absorption in the 1000-1300 cm -1 region. © 1999 MAHK "Hayka/Interperiodica".