Enhancement of ionic conduction in CaF2 and BaF2 by dispersion of Al2O3

Ionic conductivity measurements were performed on polycrystalline CaF2, BaF2 with and without dispersed Al2O3 particles. The ionic conductivity of both CaF2 and BaF2 increased by 1 or 2 orders of magnitude by dispersion of Al2O3 particles, while X-ray diffraction measurements showed there were no other phases present other than fluoride and Al2O3. The conductivity of the dispersed system strongly depended on the particle size and the concentration of Al2O3, which suggested that the high ionic-conductivity layers were formed at the interface between the ionic conductor matrix and the Al2O3 particles. The effective thickness and electrical conductivity of the interface layer at 500C were calculated, using asimple mixing model, to be 0.3 to 0.6 m and 10-3 S cm-1, respectively. 7pp 9fig