Self-diffusion in cr₂o₃II. Oxygen diffusion in single crystals

Oxygen self-diffusion in chromia (Cr2O3) single crystals was studied as a function of oxygen pressure at 1100°C, using the gas-solid isotope exchange method. The diffusion experiments were performed in H2-H2 18O atmospheres. After the diffusion anneal, the 18O diffusion profiles were determined by secondary ion mass spectrometry and the diffusion coefficients were computed using a general solution for the Fick's second law, taking into account evaporation and exchange at the surface. Our results show that oxygen diffusion coefficients at 1100°C do not depend on the oxygen pressure and are smaller than values given in the literature. Comparison with results concerning chromium self-diffusion in the same Cr2O3 single crystals clearly indicates that oxygen diffusion is faster than chromium diffusion.