Thermal features and physical properties of sulfur modified barium vanadate glasses

Abstract

Differential scanning calorimetry (DSC) and XRD were used to investigate the role of sulfur in the network of V2O5–Fe2O3–BaO glasses. The crystallization kinetics of the glasses were investigated under non-isothermal conditions applying the formal theory of transformations for heterogeneous nucleation to the experimental data obtained by DSC. The activation energy for the glass transition (E g) was derived from dependence of the glass-transition temperature (T g) on the heating rate. Similarly the activation energy of the crystallization (E c) and the frequency factor (K 0) were determined. The results reveal the increase of the activation energy for glass transition was attributed to the increase in the rigidity and the cross-link density of these composites. The evaluated thermal stability decreases with increasing sulfur content. The phases of BaFe2O4, V2O5 and FeVO4 micro-crystallites in the remaining amorphous matrix have been identified by X-ray diffraction.