It was recalled that Al had only one single stable isotope, plus radio-isotopes which were difficult to apply routinely in radiotracer diffusion experiments. Therefore, it was a considerable challenge to measure Al diffusivities. The novel approach used here consisted of using the long half-life radioactive isotope 26Al as a pseudo-stable isotope whose depth distribution could be analyzed using secondary ion mass spectrometry after diffusion experiments. mullite (Al4+2xSi2−2xO10−x, 0.2< x < 0.5) was chosen for the demonstration. The method was universally applicable to the entire family of Al-containing oxides.

26Al Diffusion Measurement in 2/1-Mullite by Means of Secondary Ion Mass Spectrometry. P.Fielitz, G.Borchardt, M.Schmücker, H.Schneider: Solid State Ionics, 2006, 177[5-6], 493-6