Crystallization kinetics of tellurium-rich Se–Te–Sn glassy alloys

Abstract

Differential scanning calorimetry (DSC) has been used to study the non-isothermal crystallization kinetics of Se30Te70−xSnx (for x = 0, 1.5 2.5 and 4.5) glassy alloys. Characteristic kinetic parameters say glass transition temperature (T g), peak crystallization temperature (T p) and melting temperature (T m) are determined from the DSC curves, recorded at four different heating rates, i.e., 9, 12, 15, 18 K min−1. The characteristic temperatures T g, T c and T m are found to increase with an increase in Sn concentration as well as with the heating rate (α). The increase in T g, T p and T m may be ascribed to the increase in cross-linking of amorphous network due to the dispersion of Sn into the Se chains. The activation energy of glass transition (E g), crystallization activation energy (E c) and Avrami exponent (n) have been evaluated from the heating rate dependence of T g, T c and T p using Kissinger, Mahadevan, Augis-Bennett and Moynihan methods. Thermal stability and glass-forming ability of amorphous Se30Te70−xSnx alloy have also been examined. Our results show that Se30Te70−xSnx composition, with thermal stability parameter H R > 0.5, is thermally stable and has characteristics of good glass former. Further, the composition corresponding to x = 1.5 is found to be thermally more stable as compared to the other compositions.