Oxygen self-diffusion in corundum (alpha-Al2O3): a conundrum

Citation
Ah. Heuer et Kpd. Lagerlof, Oxygen self-diffusion in corundum (alpha-Al2O3): a conundrum, PHIL MAG L, 79(8), 1999, pp. 619-627
Citations number
25
Categorie Soggetti
Apllied Physucs/Condensed Matter/Materiales Science
Journal title
PHILOSOPHICAL MAGAZINE LETTERS
ISSN journal
09500839 → ACNP
Volume
79
Issue
8
Year of publication
1999
Pages
619 - 627
Database
ISI
SICI code
0950-0839(199908)79:8<619:OSIC(A>2.0.ZU;2-5
Abstract
Recent point-defect calculations for Al2O3 by Lagerlof and Grimes have been used to rationalize oxygen diffusion in undoped, MgO-doped and TiO2-doped Al2O3 The amphoteric nature of Al2O3 is emphasized by the calculations; oxy gen and aluminium diffusion will be dominated by oxygen vacancies and alumi nium interstitials, or oxygen interstitials or aluminium vacancies, dependi ng on whether divalent or tetravalent impurities are present in greater abu ndance. The oxygen diffusion data can be rationalized in a reasonably quant itative manner by the calculated concentrations of oxygen vacancies and oxy gen interstitials. Oxygen vacancies appear to be 2-2.5 times more mobile th an oxygen interstitials, whereas aluminium interstitials appear to be 10(3) to 10(4) times more mobile than oxygen vacancies. However, these calculati ons suggest migration energies of the oxygen point defects of 4.5-5.9 eV. T hese values are large, and it is not known whether they have any physical s ignificance.