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Publication Detail
An ab initio study of the effect of charge localization on oxygen defect formation and migration energies in magnesium oxide
  • Publication Type:
    Journal article
  • Publication Sub Type:
    Article
  • Authors:
    Mulroue J, Duffy DM
  • Publisher:
    ROYAL SOC
  • Publication date:
    08/07/2011
  • Pagination:
    2054, 2065
  • Journal:
    P ROY SOC A-MATH PHY
  • Volume:
    467
  • Issue:
    2131
  • Print ISSN:
    1364-5021
  • Language:
    EN
  • Keywords:
    ab initio, charge localization, defect formation, migration energy, magnesium oxide, ALKALINE-EARTH OXIDES, POLYCRYSTALLINE MGO, POINT-DEFECT, DIFFUSION, CRYSTALS, SOLIDS, EXCHANGE, DENSITY
  • Addresses:
    Duffy, DM
    UCL
    Dept Phys & Astron
    London
    WC1E 6BT
    England

    UCL
    London Ctr Nanotechnol
    London
    WC1E 6BT
    England
Abstract
Plane-wave density functional theory was used to study the properties of oxygen vacancies and interstitials, with different charge states, in MgO. The calculated properties were the relaxed configurations, the Frenkel defect formation energies and the energies of the migration barriers, and all properties were found to be strongly dependent on the defect charge state. The lowest energy configuration of the O2- interstitial was found to be the cube centre; however, the O- and O-0 interstitials formed dumb-bell configurations. The Frenkel defect energies were also strongly dependent on the defect charge, with the neutral pair energy calculated to be 3 eV lower than the doubly charged Frenkel pair defect energy. The migration barriers of the oxygen vacancies were found to increase as the net charge of the oxygen vacancies decreased, which suggests that vacancies with trapped electrons are much less mobile than the F2+ vacancies modelled by classical potentials. The migration of the oxygen interstitials showed particularly interesting behaviour. The O-0 interstitial was found to have a higher migration barrier than the O2- interstitial but a very low barrier (0.06 eV) was found for the O- interstitial. The results have significant implications for the reliability of classical radiation damage simulations.
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