The isothermal permeability of sintered dense discs, stabilized with 25mol%Er2O3, was studied at temperatures of between 610 and 810C; using O pressures of between 0.0001 and 1atm. It was found that the permeation rate was limited by the bulk diffusion of electron holes and by surface exchange reactions. By using Au point electrodes, it was shown that the O semi-permeability flux in the case of partial control by surface O exchange led to deviations from Nernst behavior. However, O permeation measurements revealed that the material remained a solid electrolyte with an ionic transference number which was close to unity.

H.J.M.Bouwmeester, H.Kruidhof, A.J.Burggraaf, P.J.Gellings: Materials Science Forum, 1991, 76, 165-70. See also: Solid State Ionics, 1992, 53-56, 460-8