Study of crystallization kinetics and structural relaxation behavior in phase separated Ag ₃₃Ge ₁₇Se ₅₀ glassy alloys

We report on the crystallization processes and structure (crystal phases) of Ag ₃₃Ge ₁₇Se ₅₀ glassy alloy using differential scanning calorimetry and x-ray diffraction techniques, respectively. The devitrification that gives rise to the first exothermic peak results in the crystallization of Ag ₂Se and Ag ₈GeSe ₆ phases, while the growth of GeSe ₂ accompanied by the transformation of Ag ₈GeSe ₆ to Ag ₂Se phase occurs during the second crystallization process. Different theoretical models are used to elucidate various kinetic parameters for the crystallization transformation process in this phase separated system. With annealing below the glass transition temperature, an inverse behavior between the variation of the optical gap and the band tailing parameter is observed for the thermally evaporated films. These results are explained as the mixing of different clusters/species in the amorphous state and/or changes caused by structural relaxation of the glassy network for the thermally evaporated films.