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The isothermal DSC method was used to study the crystallization kinetics of Sb2S 3 in glassy (GeS2)o.3(Zb2S3)0. 7 . The effective activation energy of crystallization (Eo/n) was evaluated from the DSC curves using the Johnson-Mehl-Avrami transition equation.The value of the effective activation energy (Ea/n = 178.4 kJ/mol) found from the isothermal DSC curves was only slightly higher than that obtained previously with the non-isothermal DTA method (Eo/n = 166.4 kJ/mol). It turns out that both methods can be used in this case.Studies of kinetics are always connected with the concept of the activation energy. The value of this in glass crystallization phenomena is associated with the nucleation and growth processes that dominate the devitrification of most glassy solids. In general, separate activation energies must be identified with the individual nucleation and growth steps in a transformation, although they ha{,e usually been combined into an activation energy representative of the overall crystallization process [1]. Studies of the crystallization of a glass upon heating can be performed in several different ways. In calorimetric measurements, two basic methods can be used, isothermal and continuous heating crystallization. In the isothermal method the sample is brought quickly to a temperature above the glass transition temperature, T~, and the heat evolved during the crystallization process at a constant temperature is recorded as a function of time. In the continuous heating method the sample is heated at a fixed rate fl, and the heat evolved is recorded as a function of temperature or time. The crystallization process can be interpreted in terms of several theoretical models. The isothermal crystallization data are usually interpreted in terms of the Johnson-Mehl-Avrami transformation equation [2][3][4].The present work is concerned with the evaluation of the effective activation energy of crystallization (E,/n) of amorphous (GeS2)x(Sb2S3) l_x, where x= 0.3,

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