Oxygen ion conductivity of the ceria-samarium oxide system with fluorite structure

Ionic conduction of oxygen in the ceria-samarium oxide system was investigated as a function of temperature, partial pressure of oxygen and the oxide composition, together with its crystal structure, density and defect structure. The ionic conductivity of (CeO₂)_1–x(SmO_1.5)_x was the highest in ZrO₂-, ThO₂- and CeO₂-based oxide systems. The system CeO₂-SmO_1.5 consisted of the solid solution with a fluorite structure atx<50 at.%. The ionic transference number was nearly unity between 600 and 900°C. With an increase in Sm₂O₃ content, the ionic conductivity gradually decreased due to a decrease in mobility of oxygen ions. The samarium oxide-doped ceria was less reducible than pure and alkaline earth oxide-doped ceria.