STRUCTURAL STUDIES OF TUNGSTATE TELLURITE GLASSES BY RAMAN-SPECTROSCOPY AND DIFFERENTIAL SCANNING CALORIMETRY

Raman spectroscopy and differential scanning calorimetry (DSC) are use d in this work to study lattice structures, crystallization behavior, effects of heat treatment and the thermal properties of a wide range o f tungstate-tellurite glasses {(100 - x)TeO2 + xWO(3)} with 5 less tha n or equal to x less than or equal to 50 mol%. We extended the glass f ormation range of this glass system up to 50 mol% of WO3 using a plati num crucible. The Raman vibrational bands and the different coordinati on states of the constituent oxides are discussed. Interesting aspects of Raman spectra and DSC were found, and this gives integrated inform ation about the short-range order of the structures of these glasses a s a function of WO3 concentration. The thermal parameters, such as the glass transition temperature (T-g), the onset of crystallization temp erature (T-o), and the heat of crystallization delta H were determined . The relation In T-g = 1.6Z + 2.3, where Z is some average coordinati on number of the constituent atoms, known for molecular and chalcogeni de glasses, was found to be satisfied by these oxide glasses up to a c ertain threshold (27.5 mol%) of WO3.