Enthalpic relaxation in Ge2Sb2Se5 glass

Differential scanning calorimetry measurements were used to study enthalpic structural relaxation of Ge2Sb2Se5 glass. The Tool-Narayanaswamy-Moynihan (TNM) model was applied to describe the relaxation behavior. The curve-fitting results showed a significant dependence on experimental conditions, true values of the TNM parameters needed to be confirmed by the alternative non-fitting methods – apparent activation energy was confirmed by evaluations from classic and intrinsic cycles, the non-linearity parameter was determined on the basis of peak-shift method. Discussion on the origin of the trend in curve-fitting results was conducted in terms of influence of either the nonlinear Cp-T dependence or anomalous relaxation behavior of the material itself. For the latter case a suggestion regarding the proceeding molecular mechanisms was made.

► Enthalpic structural relaxation in Ge2Sb2Se5 glass was studied by DSC.
► Evaluated Tool-Narayanaswamy-Moynihan parameters show dependence on experimental conditions.
► Non-fitting methods of TNM parameters evaluation specify curve-fitting results.
► Relaxation dynamics on molecular scale was discussed on the basis of TNM parameters.