Self-diffusion was measured in single crystals of -phase yttria-doped material, at 1110 to 1630C, using 18O2 and secondary ion mass spectrometry. It was found that the diffusion involved a bulk mechanism and a sub-boundary mechanism. At high temperatures, both of these were observed while, at lower temperatures, only bulk diffusion was observed. It was shown that the sub-boundary diffusion data could be described by:

D (cm2/s) = 1.0 x 1017 exp[-233(kcal/mol)/RT]

M.Le Gall, A.M.Huntz, B.Lesage, C.Monty: Philosophical Magazine A, 1996, 73[4], 919-34

The best linear fits to the solute diffusion data ([430] to [437]) yield:

O: Ln[Do] = 0.20E – 24.5 (R2 = 0.99); O(gb): Ln[Do] = 0.37E – 45.4 (R2 = 0.96)