Multi-nuclear and multi-dimensional nuclear magnetic resonance investigation of silver iodide-silver phosphate fast...

The results of a multi-nuclear nuclear magnetic resonance (NMR) study of (AgI)x(Ag2O)y(P2O5)1-x-y glasses are reported. Using the two-dimensional variable-angle correlation spectroscopy experiment, the isotropic and anisotropic chemical shift interactions of phosphorus were determined as a function of silver iodide and silver oxide composition. From these measurements we determine the average conformation of the phosphate groups. In addition, the 109Ag NMR spectra were recorded, as a function of both composition and temperature. At high silver oxide concentrations, interaction between the silver and phosphate groups has been detected, but in glasses in the series the (AgPO3)x(AgI)1-x 31P NMR is strikingly independent on the silver iodide composition. The temperature dependence of the silver NMR linewidths in these systems shows clearly the silver mobility, and at lower temperatures no evidence for multiple distinct silver binding sites was observed. The silver chemical shift is strongly dependent on both composition and temperature. The former effect is interpreted in terms of the influence on the chemical shift of binding to oxygen versus iodine.