Grain‐Boundary Diffusion of 60 Co and 51 Cr in NiO

Grain‐boundary diffusion of 60 Co and 51 Cr in bicrystals and polycrystals of NiO was measured at temperatures <0.6 T m at various equilibrium oxygen partial pressures, using a tracer‐sectioning technique. Values of D ′δ were obtained using the Whipple and Suzuoka analyses. The results show that, for both 60 Co and 51 Cr, grain‐boundary‐enhanced diffusion is observed and the temperature dependence of D ′δ is about the same as that of the respective bulk diffusivity,/). The effects of equilibrium oxygen partial pressure and the type of gram boundary on D ′δ are not detectable within experimental error.