Oxygen Transport Properties of La1 − x Ca x CrO3 − δ as an Interconnect Material of a Solid Oxide Fuel Cell

Oxygen isotope diffusion coefficients were determined for La 1-x Ca x CrO 3-δ (x = 0.1, 0.2, 0.3) via bulk and via grain-boundary diffusion as functions of calcium content (x), temperatures from 1073 to 1273 K, and oxygen partial 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 La 0.8 Ca 0.2 CrO 3-δ . the activation energy is 160 and 167 kJ mol -1 for bulk and grain-boundary diffusion, respectively. The bulk-diffusion coefficient increased with decreasing oxygen partial pressure. The oxygen vacancy diffusion coefficient was calculated as (1.7 7 ± 0.5) × 10 -9 m 2 s -1 at T = 1273 K, constant regardless of calcium content or oxygen-vacancy content. The effect of surface exchange on the oxygen permeation through La 1-x Ca x CrO 3-δ was quantitatively evaluated.