Proton-conducting Ba_(1-x)K_xCe_(0.6)Zr_(0.2)Y_(0.2)2O_(3-δ) oxides synthesized by sol-gel combined with composition-exchange method

摘要

This study reports the synthesis of proton-conducting Ba_(1-x)K_xCe_(0.6)Zr_(0.2)Y_(0.2)2O_(3-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, Ba_(1-x)K_xCe_(0.6)Zr_(0.2)Y_(0.2)2O_(3-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 CO_2. Among all sintered oxides in mis study, the Ba_(0.925)K_(0.075)Ce_(0.6)Zr_(0.2)Y_(0.2)O_(3-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 Ba_(1-x)K_xCe_(0.6)Zr_(0.2)Y_(0.2)2O_(3-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)O_3 ceramics.