Crystallization kinetics of a-Se

Abstract

Differential scanning calorimetry was used to study crystallization behavior in selenium glass under isothermal conditions. In the current work, which is the third in a sequence of articles dealing with the crystallization kinetics of complex processes, the isothermal crystallization kinetics was described in terms of the Johnson–Mehl–Avrami nucleation-growth model. The study was performed in dependence on particle size so that the advanced interpretation of characteristic kinetic functions could be employed. The complexity of the crystallization process was found to be represented by overlapping competing surface and bulk nucleation-growth mechanisms. Based on this information, the deconvolution in terms of the Johnson–Mehl–Avrami process was performed, separating the mechanisms involved. High consistency of the resulting kinetic parameters confirms the accuracy and physical meaningfulness of the deconvolution procedure. The resulting concept not only describes the isothermal crystallization process in glassy selenium very well, both qualitatively and quantitatively, but is also capable of explaining all accessible data from the literature on this topic. In addition, comparisons of the present and literature data clearly imply that the nucleation processes play a major role in the isothermal crystallization of amorphous selenium.