Self-diffusion in cr2o3III. Chromium and oxygen grain-boundary diffusion in polycrystals

Chromium and oxygen grain-boundary self-diffusion coefficients in Cr2O3 polycrystals were determined by a thick-film method, using the 54Cr isotope and isotopic exchange with 18O. Depth profiling was made by secondary-ion mass spectrometry, and the diffusion coefficients were computed using the Whipple-Le Claire equation for type B intergranular diffusion. Grain-boundary self-diffusion coefficients were determined as a function of temperature and oxygen pressure. The grain-boundary self-diffusion coefficients are lower than the few results given in the literature and do not seem to depend on the oxygen pressure. Moreover, it is found that oxygen grain-boundary diffusion is faster than chromium grain-boundary diffusion.