Structure, physical and thermal properties of WO3-GeO2-TeO2 glasses

Differential scanning calorimetry (DSC), optical absorption and Raman scattering studies have been carried out on (90-x)TeO2-10GeO(2)-xWO(3) glasses with 7.5 <= x >= 30 mol%. The Raman studies show that the glass system contains [TeO4], [TeO3+1]/[TeO3], [GeO6], [WO4] and [WO6] groups as basic structural units. From DSC thermogram, thermal properties such as the glass transition temperature (T-g), onset crystallization (T-o), thermal stability (Delta T), glass transition width (Delta T-g), heat capacities in the glassy and liquid state (C-pg and C-pl), heat capacity change (Delta C-p) and ratios C-pl/C-pg of the glass systems have been calculated. The compositional variation of the glass transition temperature (T-g) and the calculated oxygen packing density (OPD), oxygen molar volume (V-o) values have been correlated. The variations in the optical band gap energy (E-opt,) and optical basicity (Lambda(th)) with WO3 content have been discussed interms of the glass structure. (C) 2010 Elsevier B.V. All rights reserved.