Linear viscoelastic stress relaxation and calorimetric measurements were performed on a series of mixed alkali tellurite glasses of composition 0.3([xNa2O+(1-x)Li2O])+0.7TeO2 at temperatures near and above the glass transition temperature, Tg. The stress relaxation data were well described by the stretched exponential function, G(t)=G0exp[-(t/τ)β], where τ is the relaxation time, β is the distribution of relaxation times and G 0 is the high frequency modulus. The fragility, determined from the temperature dependence of τ, exhibited a minimum in the middle of the mixed alkali composition. A possible connection between the kinetic and the thermodynamic dimensions of this system was established, wherein the heat capacity change at the Tg, ΔCp(Tg), and the fragility are correlated.
ASJC Scopus subject areas
- Electronic, Optical and Magnetic Materials
- Ceramics and Composites
- Condensed Matter Physics
- Materials Chemistry