Thermal stability and percolation threshold of Ge–Se–Fe glasses

The characteristic temperatures such as the glass transition temperature (Tg), the onset temperature of crystallization (Tc) and the melting temperatures, (Tm) have been determined for glasses belonging to the GexSe100 − x − yFey (y = 2, 4 and 6 at.%). Differential scanning calorimetry and differential thermal analysis measurements have been used for their determination. These temperatures have been used to evaluate the thermal stability of the investigated glassy alloys using Dietzel (ΔT) and Hruby (Hr) criteria. The variations of ΔT and Hr with the average coordination number, n, have been specified. It is found that both ΔT and Hr exhibit a maximum at n = 2.4. This observation is a realization of Phillips'–Thorpe threshold where the maximum stability of the network is just obtained if the percolation threshold limit is reached. The overall mean bond energies of the studied compositions have also been calculated and their correlation with the glass transition temperature is discussed.