Electrical properties optimization of calcium Co-doping system: CeO2-Sm2O3

In order to optimize the electrical properties of co-doped ceria electrolytes, Ce0.8Ca0.15Sm0.05O2-delta (CCS) sintered at different temperatures (1150 degrees C, 1200 degrees C, 1250 degrees C, 1300 degrees C and 1350 degrees C for 8 h) have been prepared and systematically investigated. It is found that among these samples sintered at different conditions, the electrical conductivity (sigma) measured at 800 degrees C can be ranked as: CCS1250 degrees C: sigma(800 degrees C)(CCS1250 degrees C) = 2.38 x 10(-2) S cm(-1) > CCS1200 degrees C: sigma(800 degrees C)(CCS1200 degrees C) = 1.81 x 10(-2) S cm(-1) > CCS1150 degrees C: sigma(800 degrees C)(CCS1150 degrees C) = 1.50 x 10(-2) S cm(-1) > CCS1300 degrees C: sigma(800 degrees C)(CCS1300 degrees C) = 1.26 x 10(-2) S cm(-1) > CCS1350 degrees C: sigma(800 degrees C)(CCS1350 degrees C) = 0.68 x 10(-2) S cm(-1). The electrical conductivity of CCS increases with the increase of sintering temperatures, and the 1250 degrees C-sintered sample presents the highest conductivity because of the best microstructures. However, the electrical conductivity of CCS decreases when the sintering temperatures goes beyond 1250 degrees C. We attribute this to the phase instability. It reveals that microstructures and the phase stability have important effects on the optimization of electrical properties for the co-doped ceria electrolytes. Copyright (C) 2012, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved