Enhancing densification and electrical properties of Sm-doped ceria with Ca and Zn as sintering aids

Ca and Zn were incorporated as sintering aids in Sm-doped ceria resulting in materials of general formula A0.02Sm0.08Ce0.9O1.94 for their use as solid electrolytes in Low Temperature-SOFCs. The synthesis was performed with 20 hours of mechanochemical ball-milling and XRD analyses revealed a cubic fluorite-like structure of the ceria and a promoted crystallinity with heat treatments up to 1500 degrees C. SEM images showed microstructures with larger grain sizes and less remnant porosity in the Zn-containing systems. Zn improved the relative density (92.95 %) of SDC when sintered at low temperatures such as 1200 degrees C, however, both Ca and Zn increased the electrical conductivity, with the highest value of 8.39 x 10-2 S/cm at 650 degrees C for the Zn-SDC system. Pure SDC and Ca-SDC resulted in lower relative densities and enhanced thermal insulation properties when sintered at 1200 degrees C.