Structural characterization and phase transformation kinetics of Se58Ge42-xPbx (x=9, 12) chalcogenide glasses

The glass transition behavior and crystallization kinetics of Se58Ge42-xPbx (x = 9, 12) have been investigated using Differential Scanning Calorimetry (DSC) at five different heating rates under non-isothermal conditions. It has been observed that these glassy systems exhibit single glass transition and double crystallization on heating. The XRD pattern revealed that the considered glasses get crystallized into GeSe2 and PbSe/Se phases after annealing at 633-643 K for 2 h. The GeSe2 and Se phases were found to crystallize in monoclinic structure while, PbSe phase crystallizes in cubic structure. Besides this, a mixed phase was also observed in DSC thermograms after annealing. The kinetic studies include determination of various parameters such as Avrami exponent (n), frequency factor (K-o), dimensionality of growth (m), the activation energy for glass transition (E-t) and for crystallization (E-c). The values of E-t increases while that of E-t decreases after annealing. Also, dimensionality of growth decreases to one dimension from two and three dimensions after annealing. (C) 2009 Elsevier B.V. All rights reserved.