Studies on Ge xSb 40− xSe 60 glasses by differential scanning calorimetry and thermomechanical analysis

Abstract

Calorimetric and dilatometric thermal properties of bulk Ge x Sb 40− x Se 60 glasses ( x = 15, 20, 25, 27, 32, 35) have been investigated by differential scanning calorimetry (DSC) and thermomechanical analysis (TMA). The variations of the difference in specific heat capacity between glass and undercooled liquid ... Cp and of the glass-transition temperature Tg on the average coordination number Z have been specified. It has been found from the dependence of T g on the heating rate that the parameter B, related to configurational changes in the structure, reaches a maximum at Z = 2.67 (i.e. for Ge 27 Sb 13 Se 60), while Δ C p values remain almost constant at Z ≥ 2.67. The apparent activation energy of glass transition E t for both the methods has been compared. Threshold-like behaviour at Z = 2.67 of the change in the fragility m has also been observed for both the methods. The softening temperature T s and the coefficient of thermal expansion in glass α g determined by TMA have exhibited a feature at Z = 2.67 as well.