Kinetics of non-isothermal crystallization of chalcogenide glasses from the Sb32As5S48I15 system

The work considers the kinetics of non-isothermal crystallization, especially from the point of view of the possibility of applying the Augis-Bennett method for the determination of activation energy. The necessity of introducing the usual approximation T >> T-0 was analyzed. It was shown that the method can be applied not only in the cases when T >> T-0, but also when T > T-0 that is, when the two temperatures differ only by about 10%. We show also that the application of the Augis-Bennett formula in such cases is more accurate the higher the value of the Avrami index n is. The method was applied to study the crystallization kinetics of the glass Sb32As5S48I15. The results obtained by differential scanning calorimetry (DSC) under non-isothermal conditions were also analyzed using the Kissinger and Matusita method. In the process of glass heating, a single peak is observed for glass transformation and a double peak for glass crystallization. The activation energies of glass transition (E-g) and crystallization (E-c) were determined, as well as the value of the Avrami index n for the second crystallization process. The obtained values for n and m indicate that the crystallization phase involves three-dimensional nucleation and growth. On the other hand, in agreement with the obtained results of the theoretical analysis, such n value justifies the application of the Augis-Bennett method for the investigated glass for which T and T-0 do not differ significantly. (c) 2007 Elsevier B.V. All rights reserved.