Modeling of thermal studies on melt quenched Ge 18 Bi 4 Se 78 chalcogenide

The crystallization characteristics for Ge 18 Bi 4 Se 78 glass are studied in this work by means of differential thermal analysis (DTA) under non-isothermal conditions. One stage endothermic glass transition and one exothermic crystallization are observed in the DTA curves. The results of topological constraints for Ge 18 Bi 4 Se 78 glass show that the calculated value of glass transition temperature (T g ) is very close to that of the experimental results. The as-prepared, as well as the annealed samples, are examined using x-ray diffraction (XRD), energy dispersive x-ray spectroscopy (EDX), scan electron microscope (SEM) techniques. Avrami’s exponent (n) found to have an average value of 1.61 ± 0.2 reveals a mixture of one dimensional and surface nucleation stages of growth. Many models are used to estimate the activation energies for glass transition (E g ) and crystallization (E c ). The crystallization process was found to be described by the Sestak- Berggren SB(M, N) model.