Ionic conductivity properties and super(19)F NMR investigation of Ln sub(1-y)Cd sub(y)F sub(3-y) (Ln identical with Ce, Nd) solid solutions with tysonite-type structure. Part II: super(19)F NMR investigation

A super(19)F NMR investigation of anion deficient solid solutions of Ln sub(1-y)Cd sub(y)F sub(3-y) (Ln identical with Ce, Nd) with the tysonite-type structure has been carried out as a function of temperature. Exchange processes, at first between the F sub(1) and F sub(2) sublattices, then between the F sub(1) and F sub(3) ones, have been identified at increasing temperature between three initial fluoride sublattices. The F sub(1) sublattice of the tysonite-structure appears at the same time as the first sublattice that is mobile at low temperatures and the sublattice where guest-induced vacancies are preferentially located. Correlations have been established between the F super(-) ion diffusion and the transport properties (Part I) determined by impedance spectroscopy.