Abstract
The crystallization kinetics of glassy Se and binary Se98M2 (M=Ag, Cd, Zn) alloys have been studied at different heating rates (5, 10, 15, 20 Kmin-1) using Differential Scanning Calorimetric (DSC) technique. The crystallization temperature (Tc) is determined from exothermic peak obtained in DSC scans of present samples. The variation in peak crystallization temperature (Tc) with the heating rate (β) has been used to investigate the growth kinetics using Kissinger, Augis-Bennet and Matusita-Sakka models. The activation energy of crystallization (Ec) has been found to increase with Ag additive and to decrease with Zn and Cd additive. The value of various kinetic parameters such as rate constant (Kp), Avrami index (n), thermal stability (S) and Hruby number (Hr) have been calculated under non-isothermal mode. The maximum change in different kinetic parameters has been found after the incorporation of Ag additive.
Highlights
The crystallization kinetics of glassy Se and binary Se98M2 (M = Ag, Cd, Zn) alloys have been studied at different heating rates (5, 10, 15, 20 K·min–1) using Differential Scanning Calorimetric (DSC) technique
Thermal analysis of chalcogenide glasses in term of crystallization kinetics is of particular interest from fundamental and applications point of views
Measurements were made under almost identical conditions at four different heating rates 5, 10, 15 and 20 Kmin–1 so that a comparison of various kinetic parameters of crystallization could be made in order to understand the effect of Ag, Cd and Zn element in binary Se98M2 alloy
Summary
Thermal analysis of chalcogenide glasses in term of crystallization kinetics is of particular interest from fundamental and applications point of views. From analysis of the experimental data they confirmed the presence of space charge limited conduction (SCLC) in all the glassy materials They observed an increase in density of defect states (DOS) in case of Sb and a decrease in (DOS) for Ge. The change in DOS on impurity incorporation is explained in terms of the change in structure of these glasses. Technique in Non-Isothermal Mode conductivity has been reported by Khan et al in thin films of glassy Se95M5 (where M = Ga, Sb, Bi) in order to identify the conduction mechanism and to observe the doping effect of different metals on amorphous selenium [13] They found that the conduction in high temperature range (314 - 375 K) is due to thermally activated tunnelling of charge carriers in the band tails of localized states; and in the low temperature range (219 - 314 K) conduction takes place through variable range hopping in the localized states near the Fermi level.
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