The effect of Sr on the properties of Y-doped ceria electrolyte for IT-SOFCs

Effect of Sr doping on the ionic conductivity of Y2O3-doped ceria (YDC) with the general formula of Ce0.8Y0.2-xSrxO2-delta (x = 0, 0.05, 0.10 and 0.15) was investigated. The phase identification, microstructures, thermal expansion and ionic conductivities of samples were studied by X-ray diffraction (XRD), scanning electron microscopy (SEM), dilatometry and AC impedance spectroscopy (IS). The results showed that the samples of co-doping with Y and Sr can result in higher ionic conductivity and lower activation energy than those of Y singly doped ceria in the temperature range of 450-750 degrees C. As the substitution amount of Sr for Y increased up to 25 mol% (Ce0.8Y0.15Sr0.05O2-delta), the sample attained the optimum ionic conductivity. At 750 degrees C, its ionic conductivity is 4.98 x 10(-2) S cm(-1), which is twice as high as that of Ce0.8Y0.2O1.9. In addition, experimental results also indicated that the grain conduction dominates the total ionic conductivity. (C) 2009 Elsevier B.V. All rights reserved.