Preparation and characterization of glasses in the Ag 2S + B 2S 3 + GeS 2 system

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The glass forming range of the Ag 2S + B 2S 3 + GeS 2 ternary system was investigated for the first time and a wide range of ternary glasses were obtained. The Archimedes’ method was used to determine the densities of the Ag–B–Ge glasses. The thermal properties of these thioborogermanate glasses were studied by DSC and TMA. The Raman, IR and NMR spectroscopy were used to explore the short-range order structure of the binary (Ag–B) and (Ag–Ge) and ternary (Ag–B–Ge) glasses. The results show the presence of bridging sulfur tetrahedral units, GeS 4/2 and AgBS 4/2, and trigonal units, BS 3/2, in the ternary glasses. Non-bridging sulfur units, AgSGeS 3/2 and Ag 3B 3S 3S 3/2 six membered rings, are also observed in these glasses at higher Ag 2S modification levels because the further addition of Ag 2S results in the degradation of the bridging structures to form non-bridging structures. The NMR studies show that Ag 2S goes into the GeS 2 subnetwork to form Ag 3S 3GeS 1/2 groups before going to the B 2S 3 subnetwork. In doing so, it is suggested that B 10S 20 supertetrahedra exist in Ag 2S + B 2S 3 and Ag 2S + B 2S 3 + GeS 2 glasses. Significantly B–S–Ge bonds form in the B 2S 3 + GeS 2 glasses, whereas they appear to be absent in the ternary glasses. From these observations, a structural model for these glasses has been developed and proposed.