Synthesis and properties of CuO-doped Ce0.9Gd0.1O2−δ electrolytes for SOFCs

Abstract The effects of copper oxide (CuO) addition on the crystal structure, densification and microstructure of Gd-doped ceria (Ce0.9Gd0.1O2−δ, CGO) synthesized by the polymeric precursor method have been studied. Ce0.9−xGd0.1CuxO2−δ (0≤x≤0.01) precursor powders were calcined at 600 °C for 1 h and the phase formation was studied by powder X-ray diffraction combined with Rietveld refinement analysis. Relative density measurements and microstructural analysis were performed on pellets sintered in the temperature range 1000–1100 °C in air. The effect of CuO as a sintering aid becomes more visible when its content is in the 0.5–1 mol% range where the relative densities are found to be 98% for sintering temperature as low as 1000 °C. A remarkable reduction (up to ~500 °C) in the sintering temperature for 1 mol% CuO-doped CGO ceramics is observed together with the formation of a dissolved phase of Gd2O3–CeO2–CuO. Ce0.89Gd0.1Cu0.01−yO2−δ sintered at 1000 °C shows total electrical conductivity of 15.5 mS cm−1 at 600 °C slightly higher than Ce0.9Gd0.1O2−δ sintered at 1500 °C (12.4 mS cm−1).