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Article Dans Une Revue Physical Review Materials Année : 2021

Diffusion mechanism of bound Schottky defect in magnesium oxide

Résumé

In simple ionic crystals, intrinsic point defects must satisfy electrical neutrality and exist as Schottky defects. In magnesium oxide (MgO), a Schottky defect is then a combination of anionic and cationic vacancies. Since vacancies are charged, the stable configuration of the Schottky defect corresponds to a bound pair of vacancies of opposite signs. In this study, we investigate the kinetics of formation and migration of such a bound pair on long timescales reaching in some cases thousands of seconds using the kinetic activation-relaxation technique, an off-lattice kinetic Monte Carlo method with an event catalog built on-the-fly during static molecular simulations. We show that the diffusion of this bound Schottky defect involves the migration of vacancies bounded to the first and third neighbor sites of the crystal structure with an apparent migration energy which cannot be inferred from the migration energies expected from isolated defects. Overall, this study gives insights and constraints on the oxygen diffusion mechanism reported experimentally in high-purity MgO samples.

Dates et versions

hal-03182863 , version 1 (26-03-2021)

Identifiants

Citer

Sami Mahmoud, Philippe Carrez, Marie Landeiro dos Reis, Normand Mousseau, Patrick Cordier. Diffusion mechanism of bound Schottky defect in magnesium oxide. Physical Review Materials, 2021, Physical Review Materials, 5 (3), pp.033609. ⟨10.1103/physrevmaterials.5.033609⟩. ⟨hal-03182863⟩
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