EFFECT OF IN IMPURITY ON CRYSTALLIZATION KINETICS OF (SE.7TE.3)(100-X)IN-X SYSTEM

The effect of In impurity on the crystallization kinetics and the chan ges taking place in the structure of (Se7Te3) have been studied by DTA measurements at different heating rates (alpha=5 deg . min(-1), 10 de g . min(-1), 15 deg . min(-1) and 20 deg . min(-1)). From the heating rate dependence of the values of T-g, T-c and T-p, the glass transitio n activation energy (E(l)) and the crystallization activation energy ( E(c)) have been obtained for different compositions of (Se7Te3)(100-x) In-x (0 less than or equal to x less than or equal to 20). The variati on of viscosity as a function of temperature has been evaluated using Vogel-Tamman-Fulcher equation. The crystallization data are analysed u sing Kissinger's and Matusita's approach for non-isothermic crystalliz ation. It has been found that for samples containing In=0, 10, 15, 20 at%, three dimensional nucleation is predominant whereas for samples c ontaining In=5 at%, two dimensional nucleation is the dominant mechani sm. The compositional dependence of T-g and crystallization kinetics a re discussed in terms of the modification of the structure of the Se-T e system.