Transport properties of Ba(Zr 0.8Y 0.2)O 3 − δ perovskite

Abstract

Transport properties of A 2+B 4+O 3-type perovskite, Ba(Zr 0.8Y 0.2)O 3 − δ (BZY82) dense ceramics were investigated under controlled atmospheres between 423 and 1273 K. The “charge carrier map” of BZY82 has been prepared, which shows the predominant proton, oxide ion, and hole conduction domains. The predominant proton conduction appeared below 873 K in the presence of water vapor and/or hydrogen. The proton conductivity was 4.2 × 10 − 3 S/cm at 873 K and the apparent activation energy for proton conduction was 0.38 eV between 723 and 873 K in wet 40% H 2 atmosphere ( P(H 2O) = 0.042 atm). The BZY82 also showed predominant oxide-ion conduction under dry and low P(O 2) conditions. The oxide-ion conductivity was 4.1 × 10 − 3 S/cm at 1273 K. The higher apparent activation energy for oxide-ion conduction of 0.75 eV was presumed to arise from the local distortion of BO 6 octahedra introduced by the mismatch of large Y 3+ ions (0.90 Å) doping to Zr 4+ (0.72 Å) sites and by the nature of Y 3+ ions trying to keep the C-type (cubic) earth structure.