Final published version
Research output: Contribution to Journal/Magazine › Journal article › peer-review
Research output: Contribution to Journal/Magazine › Journal article › peer-review
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TY - JOUR
T1 - A theoretical study of intrinsic point defects and defect clusters in magnesium aluminate spinel
AU - Gilbert, C. A.
AU - Smith, R.
AU - Kenny, S. D.
AU - Murphy, S. T.
AU - Grimes, R. W.
AU - Ball, J. A.
PY - 2009/7/8
Y1 - 2009/7/8
N2 - Point and small cluster defects in magnesium aluminate spinel have been studied from a first principles viewpoint. Typical point defects that occur during collision cascade simulations are cation anti-site defects, which have a small formation energy and are very stable, O and Mg split interstitials and vacancies. Isolated Al interstitials were found to be energetically unfavourable but could occur as part of a split Mg-Al pair or as a three atom-three vacancy Al 'ring' defect, previously observed in collision cascades using empirical potentials. The structure and energetics of the defects were investigated using density functional theory (DFT) and the results compared to simulations using empirical fixed charge potentials. Each point defect was studied in a variety of supercell sizes in order to ensure convergence. It was found that empirical potential simulations significantly overestimate formation energies, but that the type and relative stability of the defects are well predicted by the empirical potentials both for point defects and small defect clusters.
AB - Point and small cluster defects in magnesium aluminate spinel have been studied from a first principles viewpoint. Typical point defects that occur during collision cascade simulations are cation anti-site defects, which have a small formation energy and are very stable, O and Mg split interstitials and vacancies. Isolated Al interstitials were found to be energetically unfavourable but could occur as part of a split Mg-Al pair or as a three atom-three vacancy Al 'ring' defect, previously observed in collision cascades using empirical potentials. The structure and energetics of the defects were investigated using density functional theory (DFT) and the results compared to simulations using empirical fixed charge potentials. Each point defect was studied in a variety of supercell sizes in order to ensure convergence. It was found that empirical potential simulations significantly overestimate formation energies, but that the type and relative stability of the defects are well predicted by the empirical potentials both for point defects and small defect clusters.
KW - SPACE GAUSSIAN PSEUDOPOTENTIALS
KW - CATION DISORDER
KW - MGAL2O4 SPINEL
KW - AMORPHIZATION
KW - SIMULATIONS
U2 - 10.1088/0953-8984/21/27/275406
DO - 10.1088/0953-8984/21/27/275406
M3 - Journal article
VL - 21
JO - Journal of Physics: Condensed Matter
JF - Journal of Physics: Condensed Matter
SN - 0953-8984
IS - 27
M1 - 275406
ER -