Relationship between Johnson–Mehl–Avrami and Šesták–Berggren models in the kinetics of crystallization in amorphous materials

• A new kinetic aspect of crystallization in amorphous materials is proposed.
• Crystal dimensionality is correlated with the parameters of empirical model.
• Avrami model may also explain the complex diffusion processes in solids.
• Diffusion in amorphous materials might be highly complicated.

Over the decades, the thermal analysis community has been effectively using the Johnson–Mehl–Avrami (JMA) equation to model the crystallization kinetics of the processes occurring in solid state. In a relatively recent approach, it has been pointed out that the two-parameter autocatalytic Šesták–Berggren model SB (m, n) is also capable of simulating the crystallization kinetics of processes taking place in amorphous materials. Since then, these models competitively simulate the kinetics of crystallization in amorphous materials; though, an explicit relationship between them both has not yet been proposed. In this paper, a relationship is derived between the reaction model parameters of JMA and SB (m, n) models by employing the advanced reaction model determination methodology and its validity under phenomenological limits is discussed. The obtained results show that the JMA model is also capable of explaining the complex diffusion processes taking place in solid state, in addition to crystallization.

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