Thermal analysis of cadmium addition on the glass transition and crystallization kinetics of Se–Te–Sn glassy network

Calorimetric measurements have been performed in quaternary glassy system Se_78−xTe₂₀Sn₂Cd_x (x = 0, 2, 4, and 6) to study the thermally induced glass transition and crystallization phenomena. The characteristics kinetic temperatures (glass transition temperature $T_{\text{g}}$, onset crystallization temperature $T_{\text{o}}$, peak crystallization temperature $T_{\text{c}}$) and static melting temperature $T_{\text{m}}$ of the quaternary glassy series have been determined using their non-isothermal DSC curves. These temperatures were utilized to calculate the thermal stability $S$ and the Hruby parameter $H_{\text{R}}$ for the studied glasses. Both the activation energy of glass transition $E_{\text{t}}$ and the activation energy of crystallization $E_{\text{c}}$ for all compositions were evaluated using the well-known Kissinger's relation and the method of Augis–Bennett. Values of the fragility index $m$ and the crystallization rate factor $K_{\text{p}}$ were estimated using the activation energy values $E_{\text{t}}$ and $E_{\text{c}}$, respectively. The compositional dependence of the above-mentioned parameters was discussed on the basis of rigidity models and according to the formation of iono-covalent bonds when our glassy Se–Te–Sn system is doped with a heavy element as Cd.