Preparation and characterization of Ce0.8Y0.2−xCuxO2−δ as electrolyte for intermediate temperature solid oxide fuel cells

In this study, ultrafine Ce0.8Y0.2−xCuxO2−δ (for x = 0.00, 0.04, 0.08, 0.12, 0.16, 0.20) powders have been successfully prepared by sol-gel auto-combustion method. The samples were characterized by FTIR, TG-DSC, XRD, Raman spectroscopy, BET, TEM, SEM, AC impedance, and thermal expansion measurements. The results indicated that Ce0.8Y0.2−xCuxO2−δ powders with highly phase-pure cubic fluorite-type structure were obtained after calcining at 700 °C for 2 h; the average crystallite sizes were between 11.3 and 17.9 nm. The as-synthesized powders exhibited high sintering activity, Ce0.8Y0.2−xCuxO2−δ series electrolytes which have higher relatively dense over 95% can obtain after sintering at 1300 °C for 4 h Ce0.8Y0.12Cu0.08O1.86 electrolyte sintered at 1300 °C for 4 h exhibits the highest oxide ionic conductivity (σ800 °C = 0.029 S cm−1), lowest electrical activation energy (Ea = 0.75 eV) and moderate thermal expansion coefficient (TEC = 13.5 × 10−6 K−1, between 25 and 800 °C). Therefore, it was concluded that co-doping with appropriate ratio of Y/Cu can further improve the properties of ceria electrolytes.