Ion mobility and conductivity in fluorite-type solid solutions in the KF-MF sub(2)-BiF sub(3) systems (M = Ba, Cd) according to super(19)F NMR and conductivity data

Ion mobility and transport properties of the fluorite-type K sub(0.41)Ba sub(0.09)Bi sub(0.5)F sub(2.09), K sub(0.41)Cd sub(0.09)Bi sub(0.5)F sub(2.09), K sub(0.45)Ba sub(0.05)Bi sub(0.5)F sub(2.05), and K sub(0.45)Cd sub(0.05)Bi sub(0.5)F sub(2.05) solid solutions were studied by the super(19)F NMR spectroscopy and conductivity measurements. Analysis of super(19)F NMR spectra made it possible to assess the temperature effect on the nature of ion motions in the fluoride sublattice, identify types of ion mobility, and determine the respective temperature ranges (150-470 K). The results showed that the dominant type of ion motion is diffusion of fluoride ions in these solid solutions at temperatures above 350 K. The samples have the ionic conductivity above 10 super(-2) S/cm at 463 K.