The steady-state O permeation fluxes through dense La2NiO4+δ and La2Ni0.9Fe0.1O4+δ ceramics, studied at 973 to 1223K for membrane thicknesses of  0.6 to 2.0mm, were limited by both bulk ambipolar conductivity and surface exchange kinetics. The permeability data, in combination with total conductivity and equilibrium PO2–T–δ diagrams, were used in numerical regression analysis to extract the local chemical potential gradients, defect concentrations, partial conductivities and exchange rates. Doping with iron was found to increase O-ion mobility in K2NiF4-type lanthanum nickelate at 1173 to 1223K, whilst activation energies remain essentially similar, 69–80kJ/mol. At lower temperatures, the surface kinetics and ionic transport in La2Ni0.9Fe0.1O4+δ become both slower than those in La2NiO4+δ. Possible defect-interaction and exchange mechanisms relevant to this behavior were briefly considered.

Oxygen Nonstoichiometry and Ionic Transport in La2Ni(Fe)O4+δ. E.V.Tsipis, E.N.Naumovich, A.L.Shaula, M.V.Patrakeev, J.C.Waerenborgh, V.V.Kharton: Solid State Ionics, 2008, 179[1-6], 57-60