Tuning of Crystallization Dynamics in Se80In5Te15-xBix Chalcogenide Glassy System via Bismuth Doping: A Non-Isothermal Approach

This work describes the preparation of Se 80 In 5 Te 15-x Bi x chalcogenide glasses through a controlled melt quenching technique and investigates the influence of Bi blending on the non-isothermal crystallization dynamics of the Se 80 In 5 Te 15-x Bi x Glassy System. DSC at 5, 10, 15, 20 and 25 K min -1 different heating rates in air atmosphere was employed to define non-isothermal crystallization by considering the melting temperature (T m ), peak crystallization (T p ), on-set crystallization (T c ) and glass transition (T g ) temperature. All transition temperatures (T m , T p, T c , T g ) were considerably increased with increasing rate of heating. The crystallization activation energy (ΔE c ) and glass transition activation energy (ΔE g ) were calculated by using various approaches, which showed good consistency. The prepared Se 80 In 5 Te 15-x Bi x chalcogenide presented an amorphous structure by XRD analysis, while heat-treated alloys exhibited crystalline features. The morphological analysis was performed by FESEM for as-synthesized and heat-treated alloys. It was observed from FESEM images and EDX that particle clusters increase with Bi content, indicating the presence of Bi in the prepared alloy. Bi incorporation produces composition-dependent changes in the thermal behavior of the glassy system. With increasing Bi content, T g decreases whereas T c generally increases, and the crystallization activation energy exhibits a non-monotonic dependence on Bi concentration, indicating that Bi modifies the crystallization kinetics rather than producing a simple monotonic increase in network rigidity. The rise in configurational entropy and change in specific heat signify enhanced structural disorder and configurational rearrangement. The increasing fragility index further confirms a transition toward more fragile glass behavior. Overall, Bi substitution significantly modifies the thermal and thermodynamic characteristics of the Se 80 In 5 Te 15-x Bi x glassy system, particularly its glass-transition behavior, crystallization kinetics, thermal stability, configurational entropy, and fragility.