Structural relaxation in the glass transition region of chalcogenide amorphous semiconductors (GeS 2) 1−Y(Sb 2S 3) Y

Abstract

The structural relaxation in the glass transition of the amorphous (GeS 2) 1 − Y (Sb 2S 3) Y (0.1⩽ Y⩽0.9) system has been investigated with heat capacity data obtained from differential scanning calorimetry experiments. The heat capacity curves were analyzed by the Moynihan formulation with a Kohlrausch–Williams–Watts relaxation function φ( t)=exp[−( t/ τ 0) β ] (0< β⩽1) and we used the Narayanaswamy expression for τ 0. The values of model parameters, the non-exponentiality, β, the activation energy, Δ h, and non-linearity, x, were obtained from the best model-fitting to experimental data. The dimension in the structural relaxation decreased with increasing Y. This tendency is consistent with decreasing network dimensionality with increasing Y. The values of the non-exponentiality, β, were in the range of 0.6 to 0.8 and changed with the composition Y. The change in the network dimensionality with composition Y is responsible for the change in β for the GeS 2 rich composition range ( Y⩽0.3).