Structure, conductivity and acoustic attenuation in Ag2SO4)x(AgPO3)1−x

The structure of the (Ag2SO4)x(AgPO3)1−x glasses is investigated with 31P NMR magic angle spinning techniques. For x<0.2 the sulphate modifies the phosphate, and preferentially occupies a bridging position between two PO2−4 end units; in the sulphate-rich glasses a substantial fraction of Ag2SO4 goes into interstitial positions; the population of end units with an non-bridging SO2−4 in rather small, and almost independent of composition for x > 0.1. The structural description qualitatively agrees with conductivity, acoustic attenuation, and glass transition temperature (Tg) data. In particular, a Debye-like peak associated with the Ag+ jumping is seen at 168 K in the radiofrequency acoustic absorption of the x=0.3 glass. This suggests that silver is very mobile near the interstitial sulphates, but that its long-range diffusion is controlled by slower processes.