Conductivity relaxation experiments were carried out on a SrFeCo0.5Ox sample by suddenly changing the O partial pressure in the atmosphere, and monitoring the change in conductivity as a function of time. It was found that the re-equilibrium process obeyed Fick’s second law. By fitting the relaxation data to a solution of the diffusion equation, with suitable boundary conditions, it was possible to determine the O chemical diffusion coefficient and the activation energy. It was found that the O diffusivity was equal to 8.9 x 10-7cm2/s at 900C, and increased with increasing temperature. The activation energy was equal to 0.92eV. This was slightly lower than those for other oxides in the present system.

B.Ma, U.Balachandran, J.H.Park, C.U.Segre: Solid State Ionics, 1996, 83[1-2], 65-71