Pressure-composition isotherms for O were measured, by means of coulometric titration, at temperatures ranging from 550 to 825C and O pressures of between 0.001 and 1atm. The compositional dependence of the thermodynamic potential revealed an appreciably non-ideal behavior of the O ions on the basal plane. The O ion conductivity was measured by using a permeation technique at temperatures ranging from 600 to 850C, under O pressures of between 0.08 and 1atm. The data were then used to calculate the O chemical diffusion coefficient. It was found that the activation energy for O conductivity and diffusivity depended linearly upon the O content, according to E(eV) = 2.46-1.57x, where x ranged from 0.35 to 0.60 and was the deviation from O stoichiometry. The results were explained in terms of the interaction of mobile O ions.

M.V.Patrakeev, I.A.Leonidov, V.L.Kozhevnikov: Solid State Ionics, 1995, 82[1-2], 5-13