Self-diffusion in cr₂o₃ I. Chromium diffusion in single crystals

Abstract

Chromium self-diffusion coefficients in chromia (Cr₂O₃) single crystals were determined by both ion implantation and thick-film methods, using the ⁵⁴Cr and ⁵⁰Cr isotopes. The concentration profiles were established by secondary-ion mass spectrometry, and the diffusion coefficients were computed using a solution of Fick's law taking into account evaporation and exchange at the surface. Chromium diffusion was studied as a function of temperature T and oxygen pressure Po₂.

Both methods lead to diffusion coefficients of the same order of magnitude. The diffusion coefficients are lower than those given in the literature and do not depend on the oxygen pressure; they are well described by the relation