Oxygen transport properties of La1-xCaxCrO3-delta as an interconnect material of a solid oxide fuel cell

Oxygen isotope diffusion coefficients were determined for La1-xCaxCrO3-delt a (x = 0.1, 0.2, 0.3) via bulk and via grain-boundary diffusion as function s of calcium content (x), temperatures from 1073 to 1273 K, and oxygen part ial pressures from p(O-2) = 10(-9) to 10(4) Pa at T = 1273 K. Both bulk and grain-boundary diffusion coefficients increased with calcium content. For La0.8Ca0.2CrO3-delta, the activation energy is 160 and 167 kJ mol(-1) for b ulk and grain-boundary diffusion, respectively. The bulk-diffusion coeffici ent increased with decreasing oxygen partial pressure. The oxygen vacancy d iffusion coefficient was calculated as (1.7 +/- 0.5) X 10(-9) m(2) s(-1) at T = 1273 K, constant regardless of calcium content or oxygen-vacancy conte nt. The effect of surface change on the oxygen permeation through La1-xCaxC rO3-delta was quantitatively evaluated. (C) 2000 The Electrochemical Societ y. S0013-4651(00)03-102-5. All rights reserved.