Effect of CaO addition on the structure and electrical conductivity of the pyrochlore-type GdSmZr2O7

Polycrystalline GdSm1−xCaxZr2O7−x/2 (0 ≤ x ≤ 0.20) ceramics have been prepared by the solid-state reaction method. The effects of CaO addition on the microstructure and electrical properties of the pyrochlore-type GdSmZr2O7 ceramic were investigated. GdSm1−xCaxZr2O7−x/2 (x ≤ 0.05) ceramics exhibit a pyrochlore-type structure; however, GdSm1−xCaxZr2O7−x/2 (0.10 ≤ x ≤ 0.20) ceramics consist of the pyrochlore-type structure and a small amount of CaZrO3. The total conductivity of GdSm1−xCaxZr2O7−x/2 ceramics follows the Arrhenius relation, and gradually increases with increasing temperature from 723 to 1173 K. GdSm1−xCaxZr2O7−x/2 ceramics are oxide-ion conductors in the oxygen partial pressure range of 1.0 × 10−4–1.0 atm at each test temperature. The highest total conductivity is about 1.20 × 10−2 S cm−1 at 1173 K for the GdSm0.9Ca0.1Zr2O6.95 ceramic.