THERMAL INDUCED TRANSFORMATIONS IN GLASSY CHALCOGENIDES SIXTE60-XAS30GE10

Temperature-induced transformations are considered to be interesting characteristic properties of amorphous materials including the SixTe60-xAs30Ge10 system, with x=5, 10, 12 and 20. Density (ρ{variant}), X-ray diffraction and differential thermal analysis (DTA) were used to characterize the compositions. DTA traces of each glass composition at different heating rates from 5 to 30° C min-1 were obtained and interpreted. Fast and slow cooling cycles were used to determine the rate of structure formation. Cycling studies of materials show no memory effect but only ovonic switching action. The compositional dependence of the crystallization activation energy (E) and the coefficient of glass-forming tendency (Kgl) have been calculated. The thermal transition temperatures and associated changes in specific heat have been examined as a function of the Te/Si ratio by differential scanning calorimetry. It was found that ρ{variant} and E increase linearly with increasing tellurium content, while the heat capacity (cp) and Kgl, decrease with increasing tellurium content. E=1.54 eV and cp=0.246 J g-1 K-1 for x=20 while E=2.74eV and cp=0.22 J g-1 K-1 for x=5. © 1990 Chapman and Hall Ltd.