Theoretical analysis on the mechanism and transformation kinetics under non-isothermal conditions - Application to the crystallization of the semiconducting Sb0.06As0.36Se0.48 alloy

A procedure has been developed for analyzing the evolution with time of the volume fraction crystallized and reaction mechanism and for calculating th e kinetic parameters at non-isothermal transformations in materials involvi ng formation and growth of nuclei. Considering the assumptions of extended volume and random nucleation, a general expression of the fraction crystall ized as a function of the time has been obtained in isothermal crystallizat ion processes. The application of the crystallization rate equation to the non-isothermal processes has been carried out under the restriction of a nu cleation which takes place early in the transformation and the nucleation F requency is zero thereafter In these conditions, the correct reaction mecha nism has been obtained plotting the logarithmic form of various kinetic equ ations versus the reciprocal temperature, and choosing that equation, which gives the plot with the best lit to a straight line. The kinetic parameter s, activation energy and frequency factor, have been deduced from the slope and intercept of the above-mentioned straight line. The theoretical method developed has been applied to the crystallization kinetics of the semicond ucting Sb0.16As0.36Se0.48 alloy, thus obtaining values for the quoted param eters that agree very satisfactorily with the calculated results by other m athematical treatments. This fact shows the reliability of the theoretical method developed. (C) 2000 Elsevier Science S.A. All rights reserved.