Oxygen isotope diffusion coefficients were determined for La 1-xCa xCrO 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 0.8Ca 0.2CrO 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±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-xCa xCrO 3-δ was quantitatively evaluated.
ASJC Scopus subject areas
- Electronic, Optical and Magnetic Materials
- Renewable Energy, Sustainability and the Environment
- Surfaces, Coatings and Films
- Materials Chemistry