Glass transition and fragility of telluro-vanadate glasses containing antimony oxide

The activation energy (ΔH*) of the glass transition and the heating-rate dependence of the glass transition temperature (Tg) of V2O5–Sb2O3–TeO2 glasses were determined using differential scanning calorimetry technique. Non-isothermal measurements were performed at different heating rates φ (=3, 6, 9, 10, 13 K/min). The heating rate dependence of Tg was used to investigate the applicability of different theoretical models describing the glass transition. The application of Moynihan and Kissinger et al. models to the present data led to different values of (ΔH*) at each different heating-rate regions. This behavior was attributed to the strong heating rate dependence of the activation energy of the process. The fragility parameter (m = ΔH*/RTg) were ≲90, suggesting that these glasses may be classified as strong glasses. The viscosity, η, calculated at a few selected temperatures near the glass transition region increased with increasing Sb2O3 content at any given temperature, which is also expected. Also the compositional dependence of Tg and ΔH* was investigated.