Vibrational and thermal properties of the ternary Tl2O–V2O5–TeO2 glass-forming system.

In this work, we studied, the vibrational and the thermal properties of the Tl2O–TeO2, V2O5–TeO2 and Tl2O–V2O5–TeO2 glass-forming systems by means of Fourier Transform Infrared (FTIR) spectroscopy and Differential Scanning Calorimetry (DSC). Thermal properties, such as the glass transition temperature (Tg), thermal stability (S), and thermodynamic fragility (F), were determined and correlated with the structural characteristics of the glasses. The binary glass-forming system Tl2O–TeO2 exhibits the transformation of TeO4 trigonal bipyramids into TeO3 trigonal pyramid units due to the presence of Tl2O. The decreasing trend of Tg with Tl2O content, along with the increase of the thermodynamic fragility, indicates that the structure becomes less interconnected and floppier. Concerning the V2O5–TeO2 glass system, we observed that V2O5 causes structural modifications in the TeO2 sub-network by changing the coordination number of Te atoms. Furthermore, the glass rigidity reduces as indicated by the glass transition temperature variation with composition. We also found that the 0.5V2O5–0.5TeO2 glass exhibits the highest resistance to thermal shocks and possesses the most rigid network. Concerning the structure of the ternary glass-forming Tl2O–TeO2–V2O5 system, the incorporation of Tl2O into the mixed vanadate–tellurite glasses decreases the glass transition temperature implying that Tl2O acts as a network modifier affecting the network's rigidity. The decreasing trend of the thermodynamic fragility indicates that the glass network becomes more rigid. Finally, the significantly high values of thermal stability reveal that the ternary glass-forming system can be considered as a glass with superior resistance against thermal shocks making it an ideal candidate for relevant technological applications. [ABSTRACT FROM AUTHOR]