Enhancement of the ionic conductivity of mixed calcia/yttria stabilized zirconia

A ZrO2-based electrolyte, stabilized with 6 mol% CaO and 4 mol% Y2O3 was sy nthesized. This electrolyte consists of a single phase fluorite-type solid solution with cubic symmetry and exhibits a uniform microstructure. In the temperature range 1273-1673 K, the direct current (DC) conductivity of this electrolyte is higher than that of 12 mol% CaO-stabilized ZrO2 and compara ble to that of 8 mol% Y2O3-stabilized ZrO2, prepared with the same processi ng procedure. It was suggested, by comparing the electrical behaviors of bo th binary systems ZrO2-CaO and ZrO2-Y2O3, that the enhancement of the ionic conductivity of mixed CaO/Y2O3-stabilized ZrO2 at high temperature can be attributed to the increase in the concentration of the oxygen vacancies wit h weaker association energies. (C) 2000 Elsevier Science B.V. All rights re served.