Structure, physical and thermal properties of WO 3–GeO 2–TeO 2 glasses

Abstract

Differential scanning calorimetry (DSC), optical absorption and Raman scattering studies have been carried out on (90− x)TeO 2–10GeO 2– xWO 3 glasses with 7.5 ≤ x ≥ 30 mol%. The Raman studies show that the glass system contains [TeO 4], [TeO 3+1]/[TeO 3], [GeO 6], [WO 4] and [WO 6] groups as basic structural units. From DSC thermogram, thermal properties such as the glass transition temperature ( T g), onset crystallization ( T o), thermal stability (Δ T), glass transition width (Δ T g), heat capacities in the glassy and liquid state ( C pg and C pl), heat capacity change (Δ 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 ( Λ th) with WO 3 content have been discussed interms of the glass structure.