Effect of potassium substituted for A-site of SrCe0.95Y0.05O3 on microstructure, conductivity and chemical stability

The chemical stability of potassium substituted for A-site of SrCe0.95Y0.05O3 specimens was examined under CO2 atmosphere treated at 600 °C and further analyzed by X-ray diffractometer to see their CO2-resisted capabilities. According to thermodynamic data, the Gibbs free energy of CeO2 was lower than that of SrCO3 at the temperature of 600 °C. Thus the formation of CeO2 might be faster than that of SrCO3 in SrCeO3− based materials under CO2 atmosphere. Unfortunately, the chemical stability of SrCe0.95Y0.05O3 materials in CO2 atmosphere was reduced with increasing potassium-substituted amount. The microstructures of Sr1−xKxCe0.95Y0.05O3 sintered specimens were identified using field emission scanning electron microscope. The conductivity in moisture H2 atmosphere (RH 30%) was increased with increasing potassium-substituted concentration. The conductivity reached a maximum of 0.0081 Scm-1 at 900 °C for Sr0.95K0.05Ce0.95Y0.05O3 sintered specimens in moisture H2 atmosphere (RH 30%). Potassium substituted for A-site of SrCe0.95Y0.05O3 could improve the conductivity but not CO2-resisted capability.