Crystallization kinetics of amorphous Se.

Differential scanning calorimetry was used to study crystallization behavior in selenium glass under non-isothermal conditions. The crystallization kinetics were described in terms of the Johnson-Mehl-Avrami nucleation-growth model; activation energies and kinetic parameter m were determined. The study was performed in dependence with particle size, so that a novel approach to the evaluation of crystallization kinetics-the advanced interpretation of characteristic kinetic functions-could be employed. Extensive discussion of all aspects of a full-scale kinetic study for a complex crystallization process was performed within the framework of the introduced conception. The complexity of the crystallization process was found to be represented by very closely overlapping consecutive competing surface and bulk nucleation-growth mechanisms. Mutual interactions of both mechanisms as well as all other observed effects were explained in terms of thermal gradients, surface crystallization centers arising from the sample preparation treatments and a changing amount of volume nuclei originating from the combination of the pre-nucleation period and the actual glass preparation phase. The main objective of the study is to demonstrate the extent of so-far neglected information hidden in the characteristic kinetic functions and introduce a convenient tool for its acquisition. [ABSTRACT FROM AUTHOR]