Ionic Mobility in Pb0.9M0.1F2.1 (M = Bi, In) and Pb0.9Bi0.05In0.05F2.1 Solid Solutions with the Fluorite-Type Structure According NMR Data

Abstract

Ionic mobility in solid solutions Pb_0.9Bi_0.1F_2.1, Pb_0.9In_0.1F_2.1, and Pb_0.9Bi_0.05In_0.05F_2.1 with the fluorite structure is studied with the ¹⁹F NMR method at 150–470 K. Temperature regions associated with local motions in the fluoride sublattice of these solid solutions are determined. The ratio of “fixed” (in the NMR scale) and mobile fluoride ions in the transition region (200-300 K) depends on the temperature, concentration of MF₃ fluorides, and the nature of M³⁺ cations. Translational diffusion of fluoride ions is the predominant ionic motion in solid solutions above 300 K to cause high ionic conductivity in the samples.