Kinetics of crystallization in amorphous Se73.2Te21.1Sb5.7 under isochronal conditions:: Effect of heating rate on the activation energy

The kinetics of crystallization in a-Se73.2Te21.1Sb5.7 were determined at different heating rates (2-99 K/min) using differential scanning calorimetric (DSC) technique. It is evident from this study that the effective activation energy associated with crystallization, E-c in a-Se73.2Te21.1Sb5.7 is not constant but heating rate dependent. Attempt is made to explain this variation in terms of recent theoretical models based on the concept of variable effective activation energy. Using isoconversional method, the temperature dependence of Ec was determined. It is shown here that the apparent variation of Ec with the heating rate is a result of this temperature dependence. It is also shown that the JMA-based models (Kissinger model etc.) which assume constant effective activation energy show clear deviation from linearity giving at least two values of effective activation energy. (c) 2006 Elsevier B.V. All rights reserved.