Physical and mechanical properties of intermediate phase chalcogenide glasses with centroid compositions in the Ge-Te-In-Ag system

Abstract The optical and mechanical properties of three Te-based chalcogenide glasses, whose compositions correspond to the intermediate phase centroids in their respective binary Ge–Te, ternary Ge–Te–In and quaternary Ge–Te–In–Ag systems, were evaluated using micro-Raman and ultraviolet–visible spectroscopies, and nanoindentation. Results show a blueshift and an increase in the full width at half maxima for the most dominant Raman peak, and a decrease in the optical band gap, with successive doping of Ge15Te85 with In and Ag, which are attributed to the increased network connectivity and defect density, respectively, with doping. Nanoindentation results show that both the elastic modulus and the hardness increase with successive doping because of the enhancement in the network connectivity. Dynamic mechanical analysis shows that the storage modulus increases with frequency, indicating the dominance of the viscous part, while loss modulus and internal friction are relatively low in the binary system than the quaternary system. The measured indentation fracture toughness increases from binary to quaternary glass because of the crack deflection aided by the enhanced network connectivity.