LONTSI FOMENA, Mireille; VILLESUZANNE, Antoine; DOUMERC, Jean-Pierre; FRAYRET, Christine; POUCHARD, Michel

doi:10.1016/j.commatsci.2008.01.046

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LONTSI FOMENA, Mireille
Institut de Chimie de la Matière Condensée de Bordeaux [ICMCB]

VILLESUZANNE, Antoine
Institut de Chimie de la Matière Condensée de Bordeaux [ICMCB]

DOUMERC, Jean-Pierre
Institut de Chimie de la Matière Condensée de Bordeaux [ICMCB]

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Computational Materials Science. 2008, vol. 44, n° 1, p. 53-60

Elsevier

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Chemical bonding-scale aspects of oxygen diffusion in candidate high-k gate oxides LaAlO3 and SrTiO3 were investigated from first-principles, within density functional theory. Relaxed atomic positions, total energies and electron density maps were calculated along oxygen vacancy migration paths, for 2 2 2 supercells. Quite low activation energies were obtained (0.6 eV, in agreement with experiment) for both compounds. Microscopic factors involved in the diffusion process were investigated further by a topological analysis of the electron density, according to Bader's “Atoms in Molecules” theory. At the diffusion saddle point, transitory states such as O− or atomic oxygen may explain the activation energy low values. Finally, we propose the use of energy density variation maps, as a way to identify parts of the density that contribute to increase (resp. decrease) the diffusion barrier. By extension, this type of tool may help to gain insight in phenomena such as phase transitions, and constitute the basis of an “electron density engineering” for materials design and optimization.< Leer menos

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DFT

Atoms in molecules

High-k dielectrics

Oxide-ion diffusion

Electron density

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A density functional theory study of oxygen diffusion in LaAlO<sub>3</sub> and SrTiO<sub>3</sub>

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