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

(90-x)TeO2-10GeO2-xWO3 glasses with 7.5 < x > 30 mol% were analysed by DSC, optical absorption and Raman spectroscopy. The Raman studies show that the glass system contains [TeO4], [TeO3+1]/[TeO3], [GeO6], [WO4] and [WO6] groups as basic structural units. From the DSC thermogram, thermal properties including glass transition temperature, onset crystallisation, thermal stability, glass transition width, heat capacities in the glassy and liquid state, heat capacity change and ratios of the glass systems have been calculated. The compositional variation of the glass transition temperature, calculated oxygen packing density, and oxygen molar volume values were correlated. The variations in the optical band gap energy and optical basicity with WO3 content are discussed in terms of the glass structure.