Physical evolution in network glasses of the Ag–As–Te system Original Research Article

To understand the structural features of the Agx As50−x Te50, 3⩽x ⩽20, glass system, various properties are separately studied as a function of the average coordination number 〈r〉〈r〉. The relation between the chemical ordered covalent network model and constraint theory were applied to investigate the structural features. The overall mean energy 〈E〉〈E〉, of a covalent network for the Ag–As–Te ternary glasses is determined and was found to decrease in the range 3.85–3.408 eV. The average coordination number 〈r〉〈r〉 has been examined for the Ag–As–Te system in the light of recently suggested models for network glasses. In addition, the two topological effects, namely; the floppy to rigid transition and the structural transition occurred and resulted in some changes in chemical ordering. The values of the glass transition temperature Tg were found to depend on the composition showing a decrease from 170 to 130 °C with increase in Ag content. The thermal stability and the glass-forming tendency are calculated and they were found to have the same trend.