Topological behavior and glassy framework of GeTeSeGa chalcogenide glasses

Abstract

Te-based chalcogenide glasses own the most comprehensive infrared window among amorphous materials and have far-infrared applications such as CO2 detection. Nevertheless, the glass forming ability and thermal stability decrease for higher Te content chalcogenide glasses. Here, we report the effect of Ga addition on Te-based chalcogenide glasses by presuming that the addition of Ga may develop the configurational disorder and hence may improve the glass forming ability and thermal stability. Ge10Te80Se10-xGax (x = 0, 2, 4, 6, 8, 10 at %) bulk chalcogenide glassy alloys have been synthesized via melt quench technique. The role of Ga is studied through a semi-empirical approach. The result shows that the system is in rigid mode (total number of mechanical constraints >3). The density of the system shows an increase which is further supported by a decrease in free volume percentage. Mean bond energy and glass transition temperature have also been investigated. The energy gap shows a decrease with increase in Ga at. % and the behavior are correlated with the decrease in average single bond energy (72.7 kJ/mol to 69.7 kJ/mol) and electronegativity (2.14–2.06) of the system. From the results of covalent character (>90%), it is estimated that the compositions may be used to form stable glasses, which may be helpful in the development of an infrared system.