Crystallization kinetics of overlapping phases in Cu 6Ge 14Te 80 chalcogenide glass

Abstract

Differential scanning calorimetry (DSC) under non-isothermal conditions has been used to study the crystallization kinetics of Cu 6Ge 14Te 80 chalcogenide glass. This glass was found to have a double glass transition and double stage crystallization on heating. The crystallization activation energy ( E c) for the two crystallization stages was calculated by using three different theoretical models. The average values of E c for the first and the second peak are 154±13 kJ/mol and 178.47±12.5 kJ/mol, respectively. The crystalline phases resulting from DSC have been identified by using X-ray diffraction and scanning electron microscopy (SEM). Energy dispersive spectroscopy (EDS) attached to the SEM has been used to follow the chemical composition of the crystalline phases developed in samples annealed at temperatures corresponding to the two crystallization stages. The crystallization mechanisms were interpreted by using the Avrami exponent ( n) under non-isothermal conditions. The results indicated that the first crystallization is a one-dimensional growth, whereas the second crystalline phase forms by surface crystallization.