Oxygen surface exchange kinetics and diffusion have been studied by the isotope exchange method with gas phase equilibration using a static circulation experimental rig in the temperature range of 600-800 °C and oxygen pressure range of 0.13-2.5 kPa. A novel model which takes into account distributions of the dissociative adsorption and incorporation rates has been developed. The rates of the elementary stages have been calculated. The rate-determining stages for a La2NiO(4±δ) polycrystalline specimen have been discussed. The diffusion activation energies calculated using the gas phase equilibration method (1.4 eV) differ significantly from those calculated using isotope exchange depth profiling (0.5-0.8 eV), which was attributed to the influence of different oxygen diffusion pathways.

High density Ba0.5Sr0.5Co0.8Fe0.2O3-δ (BSCF) samples with the degree of closed porosity less than 7 % were annealed in 18

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The microstructure influence on the oxygen reduction process for the LSM-YSZ composite materials has been studied in this paper. To localize the effect of particle coarsening influence, the oxygen isotope exchange measurements with the gas phase analysis have been performed for LSM-YSZ ‰ YSZ ‰ LSM-YSZ symmetric cells during 300 and 1000 hours at T = 850°C and Po 2 = 10 -2 atm. In order to find quantitative relations the changes in the oxygen surface exchange and the diffusion coefficients and its microstructure parameters such as porosity and triple phase boundary (TPB) length have been compared. The rate determining stage of the LSM-YSZ degradation has been suggested to be the LSM-phase surface diffusion and the LSM surface diffusion coefficient have been estimated.