Exchange kinetics and diffusion of oxygen in systems based on lanthanum gallate

Oxygen isotope exchange in La2NiO4±δ

“…The scheme of the experimental rig is reported elsewhere. 13 Preliminary to the isotope exchange the sample underwent pre-treatment at 800 1C in oxygen. To prevent the obstacle of oxygen gas diffusion a circulation pump was applied.…”

“…The power index of r H is governed by the power index of adsorption rate and is close to 0.5 which is in accordance with Langmuir's model of the dissociative adsorption. The abovementioned considerations are based on the comparison of the mean values of r a and r i , however, the fact that ratio (13) is not equal to unity allows us to conclude that the oxygen incorporation rate has a relatively broad distribution. The oxygen incorporation rate value can be 1-2 orders of magnitude higher compared to the adsorption rate for the grains with the (ab)-crystallographic orientation (that corresponds to the dissociative adsorption being the rate-determining stage).…”

Rate-Determining Steps of Oxygen Surface Exchange Kinetics on Sr2Fe1.5Mo0.5O6−δ

“…Enriched 18 O oxygen was used as a label, the proportion of which in the mixture was 83.6%. A detailed description of the experimental procedure, the assessment of the accuracy of the determination of the heterogeneous exchange rate (r H , atom cm −2 s −1 ) and the oxygen diffusion coefficient (D, cm 2 s −1 ), and the calculation of the dissociative adsorption rate (r a , atom cm −2 s −1 ) and the oxygen incorporation rate (r i , atom cm −2 s −1 ) are described in [35][36][37]. During the experiment, periodical changes in the ion current corresponding to the masses 32, 34, and 36 ( 16 O 2 , 16 O 18 O, 18 O 2 ) were recorded using a quadrupole mass spectrometer Agilent 5973N.…”