Structure and Optical Conductivity of Silver Thiogermanate Glasses

Silver thiogermanate glasses x AgI · (1 - x) [yAg2S · (1 - y) GeS2] were investigated by infrared reflectance and Raman spectroscopies to study the glass structure as a function of Ag2S (0 ≤ y ≤ 0.5) and AgI (y = 0.5, 0 ≤ x ≤ 0.375) content. The results for binary glasses indicate that addition of Ag2S to GeS2 glass induces the depolymerization of the thiogermanate network by creation of terminal Ge-S- bonds. AgI was also found to affect the network structure and this was expressed by disproportionation reactions. The interactions between Ag+ ions and their sites were also investigated and discussed in relation to the high ionic conductivity of these glasses. Broad range conductivity spectra were also obtained by combining dielectric and far-infrared conductivity data.