Preparation and characterization of Ce0.8La0.2-xYxO1.9 as electrolyte for solid oxide fuel cells

In this study, ultrafine Ce0.8La0.2-xYxO1.9 (for x=0, 0.05, 0.10, 0.15, 0.20) powders were successfully prepared by the sol-gel method. The samples were characterized by fourier transform infrared (FTIR), thermogravimetric and differential scanning calorimetry (TG-DSC), X-ray diffraction (XRD), scanning electron microscopy (SEM), AC impedance and thermal expansion measurements. Experimental results indicated that highly phase-pure cubic fluorite electrolyte Ce0.8La0.2-xYxO1.9 powders were obtained after calcining at 600 degrees C. The as-synthesized powders exhibited high sintering activity, the Ce0.8La0.2-xYxO1.9 series electrolytes which have higher relative densities over 96% could be obtained after sintered at 1400 degrees C for 4 h. Ce0.8La0.15Y0.05O1.9 electrolyte sintered at 1400 degrees C for 4 h exhibited higher oxide ionic conductivity (sigma(800 degrees C)=0.057 S/cm), lower electrical activation energy (E-a=0.87 eV) and moderate thermal expansion coefficient (TEC=15.5x10(-6) K-1, temperature range 25-800 degrees C).