Proton-conducting Ba1−xKxCe0.6Zr0.2Y0.2O3−δ oxides synthesized by sol–gel combined with composition-exchange method

This study reports the synthesis of proton-conducting Ba1−xKxCe0.6Zr0.2Y0.2O3−δ (x=0.025–0.075) ceramics by using a combination of citrate–EDTA complexing sol–gel process and the composition-exchange method. Compared to the sintered oxides of similar composition prepared from conventional sol–gel powders, Ba1−xKxCe0.6Zr0.2Y0.2O3−δ oxides synthesized by sol–gel combined with the composition-exchange method are found to exhibit improved sinterability, higher conductivity, more homogeneous phase, and excellent chemical stability against CO2. Among all sintered oxides in this study, the Ba0.925K0.075Ce0.6Zr0.2Y0.2O3−δ pellet fabricated by this new method has the highest conductivity, 0.0094 S/cm at 800 °C, which is higher than those pressed from conventional sol–gel powders in the K doping range of 0–15%. Based on the experimental results, we discuss the mechanism for improvement in these properties in terms of calcined particle characteristics. This work demonstrates that Ba1−xKxCe0.6Zr0.2Y0.2O3−δ oxides synthesized by sol–gel combined with the composition-exchange method would be a promising electrolyte for H+-SOFC applications. More importantly, this new fabrication approach may be applied to other similar material systems, such as Sr-doped Ba(Ce,Zr)O3 ceramics.