Kinetic analysis of solid-state processes

A simple method for kinetic analysis of solid-state processes has been developed. A criteria capable of classifying different processes is explored here with a view toward visualizing the complexity of solid-state kinetics. They provide a useful tool for the determination of the most suitable kinetic model. The method has been applied to the analysis of crystallization processes in amorphous ZrO₂ and RuO₂. It is found that the crystallization kinetics of as-prepared sample exhibits a complex behavior under nonisothermal conditions. This is probably due to an overlapping of the nucleation- and crystal-growth processes at the beginning of crystallization. As a consequence, the Johnson–Mehl–Avrami nucleation-growth model cannot be applied. A two-parameter autocatalytic model provides a good description of the crystallization process under isothermal and nonisothermal conditions.