Defect processes in MgAl2O4 spinel

• Published in: Solid state sciences Vol. 10; no. 6; pp. 717 - 724
• Main Authors: BALL, J. A, MURPHY, S. T, GRIMES, R. W, BACORISEN, D, SMITH, R, UBERUAGA, B. P, SICKAFUS, K. E
• Format: Journal Article
• Language: English
• Published: Paris Elsevier 01.06.2008
• Subjects: Condensed matter: structure, mechanical and thermal properties; Defects and impurities in crystals; microstructure; Exact sciences and technology; Inorganic compounds; Physics; Point defects (vacancies, interstitials, color centers, etc.) and defect clusters; Structure of solids and liquids; crystallography; Structure of specific crystalline solids; Aluminium oxide; 61.82.Ms Spinel; Defect density; Antisite defects; Point defects; Magnesium oxide; Digital simulation; Point defect; Interstitials; Defect clusters; Aluminium; 61.43.Bn; 61.72.Bb; Oxide; 61.72.Ji; Vacancy density; Schottky defects; Spinels; Sublattices; Crystallographic site; Defect equilibrium; Magnesium; Defect structure; Defect formation
• ISSN: 1293-2558; 1873-3085
• DOI: 10.1016/j.solidstatesciences.2007.04.005

In perfect normal MgAl2O4 spinel the Mg2+ ions occupy tetrahedral 8a sites and Al3+ ions occupy octahedral 16d sites. In reality some cations are exchanged between the cation sublattices forming pairs of antisite defects and thus a degree of 'inversion'. Here atomic simulation is used to investigate the influence that antisite defects have on the populations of other intrinsic defects, those associated with Schottky and Frenkel reactions. One consequence is that the total magnesium interstitial concentration is increased substantially over the aluminium interstitial concentration and the magnesium vacancy concentration is increased over the aluminium vacancy concentration but to a much smaller extent. The split structures of isolated interstitial defects and the stability of various defect clusters are also discussed.