Abstract
Oxygen surface exchange kinetics and diffusion were studied in Pr2NiO4 + δ (PNO) by the isotope exchange method with gas phase equilibration in the temperature range of 600–800 °C and oxygen pressure range of 0.33–1.62 kPa. The oxygen heterogeneous exchange rate (rH), oxygen diffusion coefficient (D), rates of oxygen dissociative adsorption (ra), and oxygen incorporation (ri) were calculated along with the apparent activation energies of oxygen surface exchange and diffusion processes. The temperature dependence of rH was found to benon-linear in Arrhenius coordinates. The apparent activation energy changed from 1.4 ± 0.2 eV at T > 700 °C to 2.0 ± 0.1 eV. This might be attributed to the change in the rate-determining stage of oxygen exchange for Pr2NiO4 + δ at T ~ 700 °C, because of a shift in the ratio between ra and ri caused by the difference in their activation energies. Possible reasons for the observed changes in the rate-determining stage are discussed.
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