Oxygen diffusion and surface exchange kinetics for the mixed-conducting oxide La0.6Sr0.4Co0.8Fe0.2O3-δ

Abstract

Studies of oxygen surface exchange kinetics for La0.6Sr0.4Co0.8Fe0.2O3-δ oxide were performed using the technique of isotopic exchange of molecular oxygen with analysis of gas phase isotopic composition in a static circulation system at the temperatures of 600-800 °С in the oxygen pressure range of 0.27-2.13 kPa. The values of interphase exchange rate and oxygen diffusion coefficient were determined. The effective activation energies for oxygen exchange and diffusion processes as well as the exponents in the dependence of these values versus oxygen pressure in the double logarithmic coordinates were calculated. The process of oxygen dissociative adsorption at the surface of La0.6Sr0.4Co0.8Fe0.2O3-δ oxide was found to be the rate-determining stage.

Keywords

• oxygen isotope exchange
• oxygen diffusion
• lanthanum- strontium cobaltite-ferrite
• rate-determining stage