Kinetic study of non-isothermal crystallization in CuxGe20-xTe80 chalcogenide glasses

Results of differential scanning calorimetric (DSC) under non isothermal conditions for three compositions of the CuxGe20-xTe80 (x = 0, 1.5 and 3 at%) are reported and discussed. It is seen that these glasses exhibit a single glass transition and single-stage crystallization on heating, The activation energy for glass transition (Eg) and that for crystallization (E-c) are evaluated and their composition dependence is discussed. Furthermore. the activation energy for glass transition (E-c) and that for amorphous crystalline transformation (E-c) of the Cu1.5Ge18.5Te80 composition are found to exhibit unusual behavior which can be associated with the rigidity percolation. The crystalline phases resulting from the DSC have been identified using X-ray diffraction and the scanning electron microscopy (SEM). The results indicate a two-dimensional growth for the composition Ge20Te80, while for the compositions with x = 1.5 and 3 at%, a three- and one-dimensional growth process were recorded, respectively. The determinations of the glass-forming factor k(gl) have made it possible to discuss the glass-forming ability. (C) 2002 Elsevier Science B.V. All rights reserved.