Oxygen Diffusion in Sapphire

Oxygen self‐diffusion in alumina single crystals was investigated, using the proton activation technique to measure the 18O profiles after the samples had been exchanged with an 18O‐enriched gaseous environment. In the temperature range 1750 to 1950 K, the diffusion coefficient for a set of Czoch‐ralski‐grown samples, preannealed in air, is represented by Samples which were not preannealed showed much greater penetration of 18O and the concentration profiles in these samples were not consistent with Fickian behavior. Titania‐doped samples gave lower values of oxygen diffusion coefficient.