Structural relaxation due to sub-Tg annealing of Se98In1.5Sn0.5 chalcogenide glass

Structural relaxation during sub-Tg annealing of Se98In1.5Sn0.5 chalcogenide glass below the glass transition region was investigated using differential scanning calorimeter (DSC). On annealing at 308 K, for different annealing times, the glass transition temperature Tg increases while the fictive temperature Tf decreases. The excess enthalpy ΔH has been calculated from the knowledge of the excess specific heat ΔCp and plotted as a function of the annealing time ta. The so obtained values of Tg, Tf and ΔH indicate that the relaxation process in Se98In1.5Sn0.5 chalcogenide glass is approximately completed after 96 h of annealing at Ta = 308 < Tg. The structural relaxation activation energy ΔE was also calculated from the dependence of Tf on the heating rate and comes out to be 57.2 ± 3 kcal/mol for annealing at Ta = 308 K for ta = 12 h. The obtained value of ΔE is an indication of the fact that structural relaxation occurs in Se98In1.5Sn0.5 glass due to breaking and rearrangement of interchain weak bonds in the structure.