The diffusion of 18O in single crystals was measured at 1100 to 1500C in air (PO2 = 2 x 104Pa). The penetration profiles were measured by using secondary ion mass spectrometry, and the diffusion coefficients were deduced after allowing for evaporation of the sample and exchange of the diffusant with the ambient. The diffusion data could be described by:

D (cm2/s) = 8.6 x 10-1 exp[-431(kJ/mol)/RT]

The activation energy for diffusion agreed with the activation energy obtained from deformation studies.

J.L.Routbort, S.J.Rothman: Journal of Physics and Chemistry of Solids, 1986, 47[10], 993-8