LAUSR

Glass transitions in the Ge–Sb–Se glasses were investigated by means of differential scanning calorimetry (DSC) under non-isothermal conditions. The glass transition temperature (Tg), activation energy of glass transition (Et), and fragility index as functions of the mean coordination number (MCN) and atomic percent of Ge were examined. The maximum value of Tg in each group of the glasses occurred at the chemically stoichiometric composition, suggesting a glass transition threshold. The Et and fragility index were calculated from the heating rate dependence of Tg. Both Et and fragility index show the minima at MCN = 2.4 which can be attributed to the structural phase transition of a covalently glassy network at MCN = 2.4. The analysis of the experimental results suggests that both the chemical composition and MCN have significant effects on the glass transitions in Ge–Sb–Se glasses.