Oxygen-18 was used as a tracer to study diffusion in the c-direction of rutile single crystals at 1173 to 1473K. The distribution of the tracer was determined by means of a nuclear technique. The data were described by:

D(m2/s) = 2.4 x 10-6 exp[-2.826 x 105/RT]

D.J.Derry, D.G.Lees, J.M.Calvert: Journal of Physics and Chemistry of Solids, 1981, 42[1], 57-64