Kinetic study of non-isothermal crystallization in Cu xGe 20− xTe 80 chalcogenide glasses

Abstract

Results of differential scanning calorimetric (DSC) under non isothermal conditions for three compositions of the Cu x Ge 20− x Te 80 ( 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 ( E g) and that for crystallization ( E c) are evaluated and their composition dependence is discussed. Furthermore, the activation energy for glass transition ( E g) and that for amorphous crystalline transformation ( E c) of the Cu 1.5Ge 18.5Te 80 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 Ge 20Te 80, 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.