Ionic conductivity of multicomponent fluorite-structured fluorides

Influence of mixing of homovalent cations on the fast anionic conductivity, static permittivity, and thermal diffusivity is investigated in multicomponent fluorite-structured concentrated solid solutions of alkali earth and rare earth fluorides. Influence of mixing of alkali earth cations on electrical properties of fluoride superionics is studied in Ba0.7 − xSrxLa0.3F2.3 single crystals and Ca0.85 − xSrxNd0.15F2.15 transparent polycrystals. Influence of mixing of rare earth cations on electrical properties of fluoride superionics is studied in Ba0.75La0.25 − xNdxF2.25 and Ba0.35Sr0.35(R1, ..., Ri)0.3F2.3 (i = 1–6; Ri stands for rare earth elements) single crystals. It is shown that the ionic conductivity decreases with increasing difference between mean ionic radii of rare earth and alkali earth cations. Up to 350°C, the fastest ionic conductivity is found in Ba0.35Sr0.35La0.3F2.3 single crystals.