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.

This review focuses on recent advances in the study of segregation processes, namely modeling, segregation on single and polycrystalline samples, effects of polarization, interdiffusion, different atmospheres and exsolution of nanoparticles.

The oxygen surface kinetics of Sr₂Fe_1.5Mo_0.5O_6−δ was determined using the ¹⁶O₂/¹⁸O₂ isotope exchange method with gas phase analysis at 600–800 °C. The heterogeneous exchange rates (r_H) and the oxygen diffusion coefficients (D) were calculated by processing the concentration dependences of the ¹⁸O fraction using Ezin’s model. The rates of oxygen dissociative adsorption (r_a) and incorporation (r_i) were calculated based on a model using the three exchange type rates. It has been established that the rates r_a and r_i were comparable in this temperature range. Assumptions were made about the effect of the chemical composition of the surface on the rate of oxygen adsorption. It was found that the oxygen exchange coefficient (k) of Sr₂Fe_1.5Mo_0.5O_6−δ is comparable to that of La_0.6Sr_0.4MnO_3±δ oxide. High values of the oxygen diffusion coefficient were found for Sr₂Fe_1.5Mo_0.5O_6−δ. The values were comparable to those of the double cobaltite praseodymium-barium and exceed by more than an order those of lanthanum-strontium manganite.