Crystallization mechanisms occurring in the Se-Te glassy system

Crystallization kinetics, studied under non-isothermal conditions in dependence on particle size, is reviewed for the Se-Te glassy system, with particular focus on occurring macroscopic crystallization mechanisms. The observed complexity of the crystallization processes is explained in terms of the two previously identified mechanisms-bulk crystallization originating from nuclei randomly distributed in the volume of each glass particle (formation of these nuclei is consistent with the classical nucleation theory) and crystallization from surface/volume active centers, dislocations, structural defects, and heterogeneities originating from the mechanical damage of the material (e.g., during grinding and milling). In addition, a new crystallization mechanism, previously unobserved in this system, was revealed for hyperquenched Se95Te5 glass. The origin of this mechanism is suggested to be closely associated with the stress-induced defects contained in the highly strained structure of this glass. The strong compositional dependence of the occurrence of this mechanism then seems to be caused by the high cooperativity of the amorphous structure of the specific composition.