Cation diffusion in LaFeO3 was studied by using solid-state reaction between sintered La2O3 and Fe2O3 at 950 to 1350C in air or O2–N2 mixtures (figure 2). The LaFeO3 was the only product formed. The growth was parabolic and took place predominantly by the diffusion of Fe3+ through the LaFeO3 layer. The self-diffusion coefficient of Fe3+ was deduced from the parabolic rate constant, and at a constant activity of La2O3, aLa2O3 = 1, it exhibited Arrhenius-type behavior with an activation energy of 320kJ/mol. It appeared to be independent of the surrounding pO2, but this was attributed to a lack of equilibrium with the atmosphere during growth of the LaFeO3 layer. The LaFeO3 was probably

stoichiometric, and differences between the present diffusivity and activation energy, and published values, were explained in terms of this.

Cation Self-Diffusion in LaFeO3 Measured by the Solid State Reaction Method. J.B.Smith, T.Norby: Solid State Ionics, 2006, 177[7-8], 639-46