On the path to a universal model for crystallization kinetics: Interpretation of the Šesták-Berggren equation in terms of the nucleation-growth concept

An explicit equivalence between two dominant crystallization models, the flexible empirical Šesták-Berggren model and the physically meaningful nucleation-growth Johnson-Mehl-Avrami-Kolmogorov model, was found and quantified. The equivalence was confirmed to hold under any experimental conditions – isothermal annealing, heating from the glassy state, and cooling of the melt; the equivalence also results in identical crystal growth predictions based on the kinetic description by either of the two models. Based on this equivalence, the description of the crystallization data by the Šesták-Berggren model can be interpreted in terms of the physically meaningful nucleation-growth kinetics. Moreover, the deviations from this equivalence can now be unambiguously quantified, and the associated distortions of the crystallization peak can be attributed to concrete physicochemical interpretations. As such, the first physically meaningful interpretation is given to the autocatalytic Šesták-Berggren model (otherwise an empirical, purely mathematic function) when used for the description of the crystallization from the glassy matrix.