Differential scanning calorimetric studies on As–Te–Si glasses: Network topological effects and the composition dependence of thermal parameters

Abstract

Differential scanning calorimetric (DSC) studies have been carried out in order to understand the thermal behavior and the composition dependence of thermal parameters of As40Te60−xSix glasses (2⩽x⩽17). It is found that these glasses exhibit a single glass transition and two crystallization temperatures. The composition dependence of glass transition temperature of As40Te60−xSix glasses shows an increase with silicon content, indicating an increase in network connectivity. Further, the variation with composition of the first crystallization temperature (Tc1), the thermal stability ΔT (Tc1−Tg) and the specific heat capacity jump at the glass transition (ΔCp) suggest the occurrence of an extended stiffness transition in this system, with compositions x=4 and x=8 denoting the onset and the completion of the rigidity percolation. The chemical threshold of the system is suggested to occur at x=12.