Relation between electrical conductivity and chemical stability of BaCeO₃-based proton conductors with different trivalent dopants

Trivalent-cation-doped BaCe O3 has fairly high protonic conductivity at intermediate temperatures. This paper deals with the effects of the kind of dopant, M in Ba Ce0.9 M0.1 O3-α (M=Y, Tm, Yb, Lu, In, or Sc), on the electrical (ionic) conductivity at 400-900°C and chemical stability. It was found that the two properties are both governed by the ionic radii of the dopants and are in a trade-off relation. The electrical conductivity seems to be also affected by the electronegativity of the dopant element, i.e., the conductivity increases with increasing ionic radius and decreasing electronegativity (increasing basicity).