Thermal properties of quaternary TeO2-ZnO-Nb2O5-Gd2O3 glasses

Quaternary tellurite glass systems in the form 75TeO2-15ZnO-(10−x) Nb2O5-xGd2O3 (x=0.5, 1.0, 1.5, 2.0 and 2.5 mol%) have been prepared by the melt quenching technique. Density, molar volume and oxygen packing density of every glass composition have been measured and calculated. Differential thermal analyses (DTA) have been carried out on the prepared glass systems in the temperature range 300-800 K at heating rate 5, 10, 15, and 20 °C/min. The glass transition, Tg and crystallization, Tc temperatures values were measured by using DTA. Kinetics parameters like activation energy of relaxation structure Et, activation energy of crystallization, Ec and order of crystallization have been calculated for every glass composition. Structural parameters like number of bonds per unit volume (nb) and average stretching force constant (F¯) have been calculated to interpret the experimental data.