Reactive Ce0.8Sm0.2O1.9 powder synthesized by carbonate coprecipitation: Sintering and electrical characteristics

Ce0.8Sm0.2O1.9 (SDC) powder is synthesized by a simplified carbonate coprecipitation method, and the powder can be sintered to densify at 1100-1200 °C. SDC sintered at 1200 °C exhibits 98.6% of the theoretical density and an effective conductivity ((sigma)eff) of 0.038 S cm^-1 at 700 °C. Arrhenius plots of log((sigma)effT) vs. 1/T for SDC sintered between 900 and 1300 °C are curved at about 600 °C, giving activation energies of ~0.8 eV above 600 °C. SDC sintered at 1400 °C, however, shows decreased (sigma)eff with a higher activation energy of ~1.0 eV independent of temperature within 400-800 °C, and pinholes appear at tri-junctions of grain boundaries because of reduction of CeO2 at high temperatures.