The diffusive transport of Cr in both pure and Y-doped fine-grained alumina was investigated at 1250 to 1650C. From a quantitative assessment of the Cr diffusion profile in alumina, as obtained from electron microprobe analysis, it was found that Y-doping retarded cation diffusion, in the grain-boundary regime, by more than an order of magnitude. The Arrhenius equations for the undoped and Y-doped samples were:

δDb (cm3/s) = 4.77 x 10-7 exp[-264.78(kJ/mol)/RT]

and,

δDb (cm3/s) = 6.87 x 10-8 exp[-284.91kJ/mol)/RT]

respectively. In order to clarify the mechanism of this retardation, the effect of Y-doping upon diffusion activation energies and pre-factors was examined.

Grain-Boundary Diffusion of Cr in Pure and Y-Doped Alumina. K.Bedu-Amissah, J.M.Rickman, H.M.Chan, M.P.Harmer: Journal of the American Ceramic Society, 2007, 90[5], 1551–5