Oxygen ion conduction in barium doped LaInO₃ perovskite oxides

Oxygen ion conduction behaviors of the 0-5 mol% excess Ba-doped La _0.6Ba_0.4InO_3-δ cubic perovskite oxides have been investigated to elucidate their potential as electrolyte materials. The highest conductivity, 5.6 × 10^-2 S cm^-1 at 800 °C, is obtained at the 3 mol% excess Ba-doped composition benefiting from a supplementation of Ba²⁺ ions on the vacant A-site generated by the volatilization during the heat-treatment processes. Interestingly, all the samples except the undoped composition show curved electrical conductivity behavior in the Arrhenius plot. The activation energy is 0.50-0.52 eV in the high-temperature region above 900 °C, which is slightly lower than that of the doped LaGaO₃ system. Moreover, all the samples show significantly lower activation energy values of both the high- and low-temperature regions compared with yttria-stabilized zirconia. The 3 mol% excess Ba-doped La _1-xBa_xInO_3-δ (0.4 ≤ x ≤ 0.8) sample has also been studied. All of the compositions show a cubic perovskite structure and a nearly pure oxygen ion conduction behavior in a dry atmosphere even when p(O₂) = 1atm. The composition of x = 0.4 exhibits the highest oxygen ion conductivities.