Effect of Surface Condition on Oxygen Self‐Diffusion Coefficients for Single‐Crystal Al ₂ O ₃

Abstract

Oxygen self‐diffusion coefficients were determined for two Al 2 O 3 single crystals by the isotope‐exchange technique, using chemically polished and Ar ‐ion‐milled samples. Results represented by D=562 exp[–665(kJ/mol)/RT] cm 2 /s are lower than those for diamond‐paste‐finished samples and near Reed and Wuensch's results. The oxygen diffusion coefficient determined using crushed particles and the microscopically measured ratio of surface area to volume agreed with these values