On the structure of tungstate-tellurite glasses

A continuous network model of xWO(3)-(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, O=TeO2 trigonal pyramids, and WO6 octahedra with O=W double bonds. Most of the W atoms are found to be incorporated into single O=WO5 octahedra, with no more than several percents of these atoms occurring in 2[O=WO5] 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. (c) 2006 Elsevier B.V. All rights reserved.