Structure and electrical conductivity of BaCe _0.7In _0.1A _0.2O _3-δ (A = Gd, Y) ceramics

BaCe _0.7In _0.1A _0.2O _3-δ (A = Gd, Y) ceramics were synthesized by solid state reaction method. The microstructure and electrical properties of BaCe _0.7In _0.1A _0.2O _3-δ ceramics were investigated by means of X-ray diffraction (XRD), scanning electron microscopy (SEM) and complex impedance analysis at intermediate temperatures of 773-1073 K in different atmospheres. All BaCe _0.7In _0.1A _0.2O _3-δ ceramics exhibit a cubic perovskite structure. Relative densities of BaCe _0.7In _0.1A _0.2O _3-δ ceramics are above 92%. BaCe _0.7In _0.1Gd _0.2O _3-δ and BaCe _0.7In _0.1Y _0.2O _3-δ ceramics exhibit an excellent chemical stability against boiling water. The conductivity values of BaCe _0.7In _0.1Gd _0.2O _3-δ are higher than those of BaCe _0.7In _0.1Y _0.2O _3-δ in both air and dry hydrogen atmospheres. The highest conductivity is 4.6 × 10 ^-2 S cm ^-1 for BaCe _0.7In _0.1Gd _0.2O _3-δ ceramic in air at 1073 K. BaCe _0.7In _0.1Gd _0.2O _3-δ ceramic with a conductivity value of 1.0 × 10 ^-2 S cm ^-1 at 823 K in both air and dry hydrogen atmospheres is considered as a promising alternative for electrolytes of SOFC in view of decreasing the operating temperature and keeping both high conductivity and good chemical stability.