Determination of activation energy of amorphous to crystalline transformation for Se90Te10 using isoconversional methods

Abdelazim, Nema, Abdel-Latief, A.Y., Abu-Sehly, A.A. and Abdel-Rahim, M.A. (2014) Determination of activation energy of amorphous to crystalline transformation for Se90Te10 using isoconversional methods. Journal of Non-Crystalline Solids, 387, 79-85. (doi:10.1016/j.jnoncrysol.2014.01.012).

Abstract

The activation energies of crystallization of Se90Te10glass were studied at different heating rates (4–50 K/min)under non-isothermal conditions using a differential scanning calorimetric (DSC) technique. The activation ener-gy was determined by analyzing the data using the Matusita et al. method. A strong heating rate dependence ofthe activation energy was observed. The variation of the activation energy was analyzed by the application of thethree isoconversional methods, of Kissinger–Akahira–Sunose (KAS), Flynn–Wall–Ozawa (FWO), and Vyazovkin.These methods confirm that the activation energy of crystallization is not constant but varies with the degree ofcrystallization and hence with temperature. This variation indicates that the transformation from amorphous tocrystalline phase is a complex process involving different mechanisms of nucleation and growth. On the otherhand, the validity of the Johnson–Mehl–Avrami (JMA) model to describe the crystallization process for thestudied composition was discussed. Results obtained by directlyfitting the experimental DSC to the calculatedDSC curve indicate that the crystallization process of the Se90Te10glass cannot be satisfactorily described bythe JMA model. In general, simulation results indicate that the Sestak–Berggren (SB) model is more suitable todescribe the crystallization kinetics

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