Superionic transport in solid fluoride solutions with a fluorite structure

Results of systematic research into ionic transport in solid solutions M_{1 ? x} R_xF_{2 + x} and Na_{0.5 ? x} R_{0.5 + x} F_{2 + 2x} (M = Ca, Sr, Ba, Cd, Pb; R = rare-earth elements) with the fluorite structure are reviewed. The mechanism of anionic conduction is analyzed. The link between ionic transport and defects in the structure of these crystals is discussed. Potentialities of their application in electrochemical devices are considered.