Thermodynamic behavior and related phase transitions in SeTeSn and SeTeSnM (M = Ge, In, Pb, and Sb) chalcogenide glass ceramics

Abstract

This study addresses the critical need for a deeper thermodynamic understanding of chalcogenide glass–ceramic systems by investigating Se<inf>76</inf>Te<inf>20</inf>Sn<inf>2</inf> and Se<inf>78</inf>Te<inf>20</inf>Sn<inf>2</inf>M<inf>2</inf> (M = Ge, In, Pb, Sb) alloys. Although previous research has focused on thermal stability and crystallization behavior, limited attention has been given to the systematic analysis of specific heat behavior and its kinetic correlations near the glass transition temperature (T<inf>g</inf>). While prior studies have emphasized thermal stability and crystallization, this work focuses on the composition-dependent evolution of specific heat (C<inf>p</inf>) across the glass transition temperature (T<inf>g</inf>). Differential scanning calorimetry (DSC) was employed under non-isothermal conditions to evaluate the specific heat (C<inf>p</inf>) and derive associated thermodynamic parameters: enthalpy (H), entropy (S), and Gibbs free energy (G). Two novel kinetic–thermodynamic correlations were identified: (i) a linear relationship between the rate of conversion change Δ(dα/dT) and logβ, and (ii) a direct correlation between the specific heat jump (ΔC<inf>p</inf>) and logβ. These results offer new insights into how heating rate influences thermal transitions. The thermodynamic profiles of C<inf>p</inf>, H, S, and G exhibit continuous transition characteristics, indicating that T<inf>g</inf> functions as a dynamic threshold rather than a sharp boundary. This work contributes to a deeper understanding of glass transition phenomena and provides a framework for tailoring phase-change behavior in functional chalcogenide materials. © 2025