Effects of Er2O3 content on heat capacity, thermodynamic functions and vitrification characteristics of Er3Â +-doped tellurite glass

A series of samples of high-purity glasses TeO2-WO3-La2O3-Er2O3-Bi2O3 with different mole content of Er2O3 was synthesized. The total content of the 3d-transition metals impurities did not exceed 0.1-2 ppm wt., the hydroxyl groups absorption near ~ 3 μm was as low as 0.001-0.01 cm− 1. The glasses have been studied by differential scanning calorimetry. Glass transition temperatures were determined; for the highest Er2O3 concentrations the thermal effects of crystallization were observed at the heating rate of 5 K/min. The temperature dependences of heat capacity C°p = f(T) in the range of 320-1050 K were found. Using the experimental data the standard thermodynamic functions were calculated: enthalpy H°(T) − H°(0), entropy S°(T) − S°(0) and Gibbs energy G°(T) − G°(0) in vitreous and “supercooled liquid” states. Model and parametric similarity of properties within the framework of statistical approach with determined correlation dependencies of parameters on composition makes it possible to predict the thermodynamic functions for other compositions of glasses within the system.