Preparation and electrical properties of a pyrochlore-related Ce2Zr2O8−x phase

A pyrochlore-related Ce2Zr2O8−x phase has been prepared in a reduction reoxidation process from Ce0.5Zr0.5O2 powders. Ce2Zr2O8−x, based on a cubic symmetry with a=1.053 nm, decomposes in nitrogen at 800 °C, but remains stable up to 900 °C in air. It shows mixed oxygen ionic and electronic conductivity. The bulk conductivity at 700 °C is 4×10−4 S cm−1 in air and 1×10−2 S cm−1 in nitrogen, and the activation energy is 1.27 eV in air. In nitrogen, the Arrhenius law is not obeyed, and a curved plot was obtained from 400 to 700 °C; then, the conductivity decreased rapidly due to the thermal decomposition of Ce2Zr2O8−x.