Synthesis, structure and electrical conductivity of BaZr _1-xDy _xO _3-δ ceramics

Dy ³⁺-doped barium zirconate ceramics, BaZr _1-xDy _xO _3-δ (x = 0, 0.05, 0.10, 0.15, 0.20), have been synthesized by pressureless-sintering method at 1973 K for 10 h in air. The structure and electrical conductivity of BaZr _1-xDy _xO _3-δ ceramics were investigated by means of X-ray diffraction, scanning electron microscopy and complex impedance spectroscopy. BaZr _1-xDy _xO _3-δ ceramics exhibit a cubic perovskite structure. The total conductivity of BaZr _1-xDy _xO _3-δ ceramics obeys the Arrhenius relation, and gradually increases with increasing temperature from 723 to 1073 K. The BaZr _0.90Dy _0.10O _3-δ ceramic exhibits the highest total conductivity at 1073 K. The measured total conductivities of the BaZr _0.90Dy _0.10O _3-δ ceramic in wet hydrogen (4% H ₂O/H ₂) and in air are 7.90 × 10 ^-3 S cm ^-1 and 7.31 × 10 ^-3 S cm ^-1 at 1073 K, respectively. The activation energy of BaZr _1-xDy _xO _3-δ (x = 0.10, 0.15, 0.20) ceramics is clearly lower than that of undoped BaZrO ₃ ceramic in both wet hydrogen and air atmospheres, and it can be concluded that the Dy ³⁺-doped BaZr _1-xDy _xO _3-δ (x = 0.10, 0.15, 0.20) ceramics are potential proton conductors.