Morphology, structure and thermal analysis of (As50Se50)100-xAgx glasses

The structural and crystallization kinetics of (As50Se50)(100-x)Ag-x (x=0, 5, 10 and 15 at.%) glasses are reported. The glass transition activation energy, E-t, decreased from 185.19 to 179.94 eV with increasing the Ag content. The crystalline phases AsSe, AgAsSe2 and Ag2Se phases were found in the annealed glasses. The structure of the annealed samples at different temperatures was examined using scanning electron microscopy. The crystallization kinetics parameters were calculated using the iso-conversional models. A slight increase in E-c(chi) from with the conversion (chi), which accounts for single-step mechanism, was found. The results of the conversion dependence of the Avrami exponent n(chi) showed an increase from 1.22 to 1.31 with the Ag content and conversion (chi) as well. The average values of n(chi) are accounted for two- and three-dimensional crystal growth with heterogeneous nucleation. Comparing the experimental DSC data with calculated ones indicated that Sestak-Berggren model was found to be suitable for describing the crystallization process of the investigated chalcogenide glasses.