2134/19331 Christopher A. Gilbert Christopher A. Gilbert Roger Smith Roger Smith Steven Kenny Steven Kenny S.T. Murphy S.T. Murphy R.W. Grimes R.W. Grimes J.A. Ball J.A. Ball A theoretical study of intrinsic point defects and defect clusters in magnesium aluminate spinel Loughborough University 2015 Magnesium aluminate spinel Defects DFT Mathematical Sciences not elsewhere classified Condensed Matter Physics 2015-11-06 15:14:15 Journal contribution https://repository.lboro.ac.uk/articles/journal_contribution/A_theoretical_study_of_intrinsic_point_defects_and_defect_clusters_in_magnesium_aluminate_spinel/9388970 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.