Ion mobility and transport in β-PbF2 doped with alkaline-earth fluorides

We have studied ion mobility and conduction in ( 1 - x) PbF2 center dot x MF2 (M = Mg2+, Ca2+, Sr2+, Ba2+; 0.05 <= x <= 0.1) solid solutions by F-19 and Pb-207 NMR and impedance spectroscopy. The results are used to analyze the factors governing the structure of the fluoride sublattice and the nature and energetics of ionic motion in the temperature range 170 - 550 K. The solid solutions are shown to have high ionic conductivity (similar to 10(-4) to 10(-3) S/cm at temperatures above 470 K, with activation energies E-a <= 0.3 - 0.6 eV) and are, therefore, potentially attractive for engineering materials with tailored electrical properties.