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)TeO2–10GeO2–xWO3 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 (Tg), onset crystallization (To), thermal stability (ΔT), glass transition width (ΔTg), heat capacities in the glassy and liquid state (Cpg and Cpl), heat capacity change (ΔCp) and ratios Cpl/Cpg of the glass systems have been calculated. The compositional variation of the glass transition temperature (Tg) and the calculated oxygen packing density (OPD), oxygen molar volume (Vo) values have been correlated. The variations in the optical band gap energy (Eopt) and optical basicity (Λth) with WO3 content have been discussed interms of the glass structure.