Crystal growth from mechanically induced defects

For the first time, infrared microscopy was used to directly confirm the presence of crystallites originating from mechanically induced defects. Differential scanning calorimetry and infrared microscopy were used to study crystallization behavior of the GeTe4 glass. Both non-isothermal and isothermal DSC crystallization data were deconvoluted by state-of-the-art methods, and the identified sub-processes were described in terms of appropriate kinetic models. While the bulk samples showed zero-order (F0) crystallization kinetics, the GeTe4 powders exhibited complex kinetic behavior describable by competing Johnson–Mehl–Avrami and autocatalytic crystallization mechanisms. The concept of crystallization from mechanically induced defects was used to explain the difference in the kinetic behavior of bulk and powdered materials. Microscopic observation of two types of crystallites being present in a partially crystallized powder grain corresponds well to the occurrence of two crystallization mechanisms identified for the DSC data. The zero-order crystallization kinetics found for the DSC data of bulk samples was verified by microscopic crystal growth rate measurements.