NUCLEAR-SPIN RELAXATION IN GLASSY IONIC CONDUCTORS

The nuclear spin relaxation behaviour in disordered ionically conducting materials is ascribed to a mechanism based on diffusion-controlled relaxation. In this target-diffusion model, relaxation is assumed to occur at interstitialcy sites, triggered by the arrival of diffusing ions. The dependence of the spin-lattice relaxation rate on the temperature, Larmor frequency and ionic concentration can all be understood with this model. The results of a nuclear spin-lattice relaxation study of the mixed-alkali effect in glasses can, on this basis, be interpreted in terms of changes in ionic mobility.