Interpretation of crystallization kinetics results provided by DSC

Differential scanning calorimetry (DSC) measurements were used to study crystallization in the Se70Te30 glass under non-isothermal conditions. The crystallization kinetics was described in terms of the nucleation-growth Johnson–Mehl–Avrami and autocatalytic Šesták–Berggren models.An extensive discussion of all aspects of a full-scale kinetic study for a complex crystallization process was performed. Number of suggestions regarding the experimental part (sample and glass preparation, temperature programs, data acquisition, etc.) was introduced to maximize precision and reproducibility of the experimental data. Complexity of the crystallization process was in this particularly described case 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 centres arising from the sample preparation treatments and changing amount of volume nuclei originating from the combination of pre-nucleation period and the very glass preparation phase. Advanced error analysis was performed for each step of the kinetic study.Objective of the presented study was to demonstrate extensity of information the differential scanning calorimetry is able to provide and, furthermore, to show how a thorough kinetic analysis may lead to reliable, valid and detailed description of complex processes as well as to interpretations of any observable trend occurring in experimental data.

► Crystallization kinetics in dependence on particle size fractions of Se70Te30 glass was studied by DSC.
► All studied fractions were described in terms of the JMA and AC models.
► Complexity of the Se70Te30 glass crystallization is given by competing surface and internal crystallization mechanisms.
► Obtained DSC data allowed explaining of the mutual interaction of the processes as well as the origin of their sequentiality.
► Supplemental studies demonstrate large amount of information and further possibilities the DSC technique offers.