Effect of acceptor substitution in perovskites La1–xAxMnO3 ± δ (A = Ca, Sr, Ba) on the kinetics of interaction of gas-phase oxygen

Resumo

The kinetics of interaction of gas-phase oxygen with oxygen of perovskite-like manganites La_{1 - x}A_xMnO_{3 ± δ} (A = Ca, Sr, Ba) at a temperature of 850°C and an oxygen pressure of 1 kPa was studied by isotope exchange of oxygen with analysis of the gas phase. The rates of the interphase exchange, dissociative adsorption, and incorporation of oxygen in the crystal lattice of perovskites La_0.7A_0.3MnO_{3 ± δ} (A = Ca, Sr, Ba) and La_1–xSr_xMnO_{3 ± δ} (x = 0, 0.3, 0.4) were calculated. The dissociative adsorption of oxygen was found to be the limiting stage of the exchange. The influence of the defective structure of oxide La_{1 - x}A_xMnO_{3 ± δ} on the mechanism of exchange with oxygen of the gas phase was discussed.