In pure LaF3 and La1−xSrxF3−x single crystals (with admixture concentrations, x,

ranging from 10−4 to 0.16) the fluorine dynamics were studied using several NMR

methods (spectroscopy, relaxometry, diffusometry) and conductivity

measurements. Previous spectroscopic and relaxometry data were here

complemented by: (i) mechanical field cycling data yielding fluorine spin-lattice

relaxation rates at high frequencies, (ii) static field gradient data yielding fluorine

diffusivities and (iii) ionic conductivity data. From the high frequency relaxation

data it was possible to extract the paramagnetic contribution thus gaining short

motional correlation times of down to almost 10−11s. The combination of

microscopic (spectra, relaxation) and mesoscopic (diffusion, conductivity) data

leads to a consistent overall picture of the fluorine ionic dynamics. In doped LaF3

the fluorine dynamics turns out to be significantly faster than in the pure system.

For the latter, however, strong aging effects were able to enhance the ionic

dynamics significantly. From the temperature dependencies of the fluorine

dynamics a qualitative picture of a hierarchy of thermally activated processes was

deduced.

Fluorine Dynamics in LaF3-Type Fast Ionic Conductors - Combined Results of

NMR and Conductivity Techniques. F.Fujara, D.Kruk, O.Lips, A.F.Privalov,

V.Sinitsyn, H.Stork: Solid State Ionics, 2008, 179[40], 2350-7