DISORDER OF IONIC MOBILITY IN CRYSTALLINE SUPERIONIC CONDUCTORS CHARACTERIZED BY F-19-NMR

Fluorine mobility in monocrystalline LaF3 is analyzed using F-19 NMR s pectroscopy. At lower temperatures the motion is restricted to F- ions in the F-1 sublattice and characterized by a strongly heterogeneous b ehavior. Our approach which is based on line shape analysis shows that the mobility can be well described by a broad distribution of correla tion times. The distribution of the correlation times and its variatio n with the temperature reflects the potential energy landscape in the superionic state.