Tracer diffusivities of Al were measured in polycrystalline mullite. The artificial Al isotope, 26Al, was used as a tracer isotope. An advanced preparation technique for the 26Al2O3 tracer source permitted the use of secondary ion mass spectrometry to analyze 26Al depth distributions in the polycrystalline material. Pre-exponential factors and activation enthalpies were determined for the compositions, Al2O3-22wt%SiO2 (high-alumina material) and Al2O3-28wt%SiO2 (low-alumina material). A strong dependence of the 26Al grain boundary diffusivity upon the composition was observed.

Aluminium Grain Boundary Diffusion in Polycrystalline Mullite Ceramics. P.Fielitz, G.Borchardt, M.Schmücker, H.Schneider: Physics and Chemistry of Minerals, 2007, 34[6], 431-6