Structure and electrical conductivity of BaCe0.85Ln0.15O3−δ (Ln = Gd, Y, Yb) ceramics

BaCe0.85Ln0.15O3−δ (Ln = Gd, Y, Yb) ceramics are synthesized by the solid state reaction method. All of BaCe0.85Ln0.15O3−δ ceramics are composed of a single perovskite-type phase. The grain size of BaCe0.85Ln0.15O3−δ (Ln = Gd, Y, Yb) ceramics decreases with decreasing the ionic radius of doped cations. BaCe0.85Y0.15O3−δ ceramic has the highest total conductivity at 1073 K in both 4% H2O-saturated H2 and air among three kinds of BaCe0.85Ln0.15O3−δ ceramics. Total conductivities of BaCe0.85Gd0.15O3−δ and BaCe0.85Y0.15O3−δ ceramics exceed 0.01 S cm−1 in both 4% H2O-saturated H2 and air above 773 K. The pre-exponential factors and activation energies of BaCe0.85Ln0.15O3−δ ceramics are similar both in 4% H2O-saturated H2 and in air. The crystal structure, relative density and grain boundary area are the main influencing factors on electrical conductivity of doped barium cerates.