Mechanism of Oxygen Permeation Through Lime‐Stabilized Zirconia

Abstract

The isothermal permeation of oxygen through was studied at 960°–1450°C and oxygen pressures of 10−3 to 1 atm on one side of the permeation cell and of 10−6–10−4 atm on the other. In the steady state, the permeating flux was directly proportional to , where varied from 2.5 to 4.0. The value of depended on the microstructure of the sample. For samples without micropores, a value of was found. These samples also contained a second phase whose composition depended on the nature and extent of impurities. For samples with nonconnected micropores, varied from 3.6 to 2.5, depending on the thickness, and the results were consistent with a mechanism in which permeation is limited partly by diffusion within the solid and partly by a surface reaction. Both the bulk and surface processes have activation energies of about 200 kJ‐mol−1.