On the structure of tungstate–tellurite glasses

A continuous network model of xWO3–(1 − x)TeO2 glasses is developed, based on quantum-chemical calculation and Raman spectra analysis, in order to relate the structural and vibrational properties with glass composition. The tungstate–tellurite glass network is shown to be formed mainly by structural units of three types, TeO4 trigonal bipyramids, OTeO2 trigonal pyramids, and WO6 octahedra with OW double bonds. Most of the W atoms are found to be incorporated into single OWO5 octahedra, with no more than several percents of these atoms occurring in 2[OWO5] paired tungstate centers. The structural and vibrational properties of tungstate–tellurite glasses of several compositions are analyzed by application of the model and a novel interpretation of the Raman spectra is suggested.