Abstract
The kinetic parameters of amorphous Se85Te10Pb5 glasses were studied for nonisothermal and predicted isothermal conditions. Differential scanning calorimetry (DSC) was used to study the kinetics of the amorphous-to- crystalline transformation at heating rates in three regimes (3-15, 20-50 and 60-99 K min(-1)). Analysis of the obtained data shows that the activation energy of crystallization is not constant but varies with the degree of conversion and, hence, with temperature; thus, the variation depends on the heating rate. The Avrami exponents indicate that the mechanism of crystallization varies from one- to two- to three-dimensional growth at low, medium and high heating rates, respectively. The reduced reaction model was observed to follow the Avrami-Erofeev mechanism, but varies from A1.5 to A2 to A3 for the different heating-rate regimes. A good fit was achieved between experimental and predicted sigmoidal curves for the crystallization fraction with increasing temperature. (C) 2014 Elsevier B.V. All rights reserved.