Oxygen Diffusion in Sapphire

Abstract

Oxygen self‐diffusion in alumina single crystals was investigated, using the proton activation technique to measure the 18 O profiles after the samples had been exchanged with an 18 O‐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 image Samples which were not preannealed showed much greater penetration of 18 O and the concentration profiles in these samples were not consistent with Fickian behavior. Titania‐doped samples gave lower values of oxygen diffusion coefficient.