Structure of WO3-TeO2 glasses

WO3-TeO2 glasses have been studied by quantum-chemical simulation and Raman spectroscopy. The results have been used to develop a model for the network of tungstate-tellurite glasses. The model allows one to correlate the structure and optical properties (in particular, the position and intensity of Raman bands) of the glasses with their composition. The network of the glasses is shown to be made up, for the most part, of three types of structural groups: TeO4 trigonal dipyramids, O=TeO2 pyramids, and O=WO5 octahedra. Any other structural units, in particular, WO4 tetrahedra, are unnecessary. The model for the network of WO3-TeO2 glasses can be used to analyze the vibrational spectra of tungstate-tellurite glasses in a broad composition range. In particular, using this model we assigned the Raman spectra of the tungstate-tellurite glasses in the range 550-950 cm(-1).