The highly phase-pure electrolyte materials with composition La1.9Ba0.1Mo1.9Mn0.1O9(LBMMO) was prepared by the sol-gel auto-combustion method for intermediate-temperature solid oxide fuel cells(IT-SOFCs). The details of gel's auto-combustion, phase evolution, sintering, thermal expansion and electrochemical performance of LBMMO were investigated by means of thermo-gravimetry(TG), X-ray diffraction(XRD), scanning electron microscopy(SEM), transmission electron spectroscopy(TEM), thermal expansion curve(TEC) and complex impedance spectra. The results showed that the highly phase-pure electrolyte LBMMO could be obtained after calcining at 600 °C. The sample sintered at 900 °C for 4 h in air exhibited a better sinterability, and the relative density of LBMMO was higher than 96%. The electrical conductivities of the sample were 6.7×10-3 and 25.9×10-3 S/cm at 700 and 800 °C in air, respectively. Results also showed that LBMMO had moderate thermal expansion(α=16.3×10-6 K-1, between room temperature and 800 °C) and an electrical activation energy equal to 1.32 eV).
In this study, ultrafine Ce0.8La0.2–x Y x O1.9(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–x Y x O1.9 powders were obtained after calcining at 600 °C.The as-synthesized powders exhibited high sintering activity, the Ce0.8La0.2–x Y x O1.9 series electrolytes which have higher relative densities over 96% could be obtained after sintered at 1400 °C for 4 h.Ce0.8La0.15Y0.05O1.9 electrolyte sintered at 1400 °C for 4 h exhibited higher oxide ionic conductivity(σ800 oC=0.057 S/cm), lower electrical activation energy(E a=0.87 e V) and moderate thermal expansion coefficient(TEC=15.5×10-6 K-1, temperature range 25–800 °C).
