Simultaneous 18O and 26Al tracer (figure 1) diffusion experiments were performed on Ti-doped single crystalline α-Al2O3. The simultaneous tracer diffusion of 18O and

26Al clearly demonstrated that the Al diffusivity in Ti-doped alumina was orders of magnitude higher than the O diffusivity. The enhanced Al diffusivity was caused by an increase in the concentration of mobile Al vacancies. The reasonably good agreement between earlier conductivity measurements and the present transport measurements indicated, in accord with theoretical work, that the migration enthalpy of Al vacancies was 3.8eV.

26Al Tracer Diffusion in Titanium Doped Single Crystalline α-Al2O3. P.Fielitz, G.Borchardt, S.Ganschow, R.Bertram, A.Markwitz: Solid State Ionics, 2008, 179[11-12], 373-9