Raman spectroscopic characterization of tellurite glasses containing heavy metal oxides

Raman spectroscopy was used for the characterization of TW (100-x)TeO2-xWO(3), TWP 60TeO(2)-(40-x)WO3-xPbO and TAW (85-x)TeO2-15Ag(2)O-xWO(3) system. The Raman spectra of the glasses were interpreted in terms of the structural transformations produced by the modifiers. The main results show the progressive transformation of trigonal bipyramids TeO4 to TeO3+1 polyhedron for TeO2-WO3 glasses with increasing WO3 content, the Te environment changes from trigonal bipyramids TeO3 to TeO3+1 polyhedral for TeO2-Ag2O-WO3 glasses with increasing WO3 content. On the other hand, the Te environment changes from TeO3/TeO3+1 to TeO4 for TeO2-WO3-PbO glasses with increasing PbO content. Raman measurements reveal the dual role of lead atoms in the ternary system TeO2-WO3PbO. WO3 addition was found to promote the formation of TeO3/TeO3+1 units and WO6 units in all the glasses at the expense of TeO4 units and WO4 units. Results show that in all the systems, the coordination state of W ion change from 4 to 6 when WO3 concentration increases beyond 30 mol%. (C) 2009 Elsevier B.V. All rights reserved.