Structural relaxation in the glass transition region of chalcogenide amorphous semiconductors (GeS2)1-Y(Sb2S3)Y

The structural relaxation in the glass transition of the amorphous (GeS2)(1-Y)(Sb2S3), (0.1 less than or equal to Y less than or equal to 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 phi(t) = exp[-(t/tau(0))(beta)] (0 < beta less than or equal to 1) and we used the Narayanaswamy expression for tau(0). The values of model parameters, the non-exponentiality, beta, the activation energy, Delta 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, beta, 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 beta for the GeS2 rich composition range (Y less than or equal to 0.3). (C) 1998 Elsevier Science B.V. All rights reserved.