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 degrees C. SDC sintered at 1200 degrees C exhibits 98.6% of the theoretical density and an effective conductivity (sigma(eff)) of 0.038 S cm(-1) at 700 degrees C. Arrhenius plots of log(sigma T-eff) vs. 1/T for SDC sintered between 900 and 1300 degrees C are curved at about 600 degrees C, giving activation energies of similar to 0.9 eV below 600 degrees C and similar to 0.8 eV above 600 degrees C. SDC sintered at 1400 degrees C, however, shows decreased sigma eff with a higher activation energy of similar to 1.0 eV independent of temperature within 400-800 degrees C, and pinholes appear at tri-junctions of grain boundaries because of reduction of CeO2 at high temperatures. (c) 2005 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.