OATAO - Open Archive Toulouse Archive Ouverte Open Access Week

First-principles calculations of the diffusion of atomic oxygen in nickel: thermal expansion contribution

Megchiche, El Hocine and Amarouche, Mohand and Mijoule, Claude First-principles calculations of the diffusion of atomic oxygen in nickel: thermal expansion contribution. (2007) Journal of Physics : Condensed Matter, vol. 19 (n° 29). p. 296201. ISSN 0953-8984

[img]
Preview
(Document in English)

PDF (Author's version) - Requires a PDF viewer such as GSview, Xpdf or Adobe Acrobat Reader
258kB

Official URL: http://dx.doi.org/10.1088/0953-8984/19/29/296201

Abstract

Within the framework of density functional theory using the projector augmented-wave (PAW) method, we present some energetic properties of atomic oxygen interstitials in crystalline Ni, i.e. the insertion and activation energies of the O diffusion. Concerning the activation energy, two pathways for the migration process are studied. The charge transfer process between atomic oxygen and nickel atoms is analysed in the interstitial sites. We find that the interstitial octahedral site (O site) is lower in energy than the tetrahedral site (T site). The most favourable pathway for the migration between two octahedral sites corresponds to an intermediate metastable state located in a tetrahedral site. Concerning the charge transfers we find that the atomic oxygen ionizes as O− and that the electron migrates essentially from the Ni nearest neighbours of atomic oxygen. In addition, the thermal expansion contribution through the dilatation of the solid is studied. When the thermal expansion is introduced, we show that the insertion process is stabilized and that the tetrahedral insertion energy becomes nearly equal to the octahedral ones. However, the activation energy decreases with the dilatation. Taking into account the thermal expansion effects, our results are consistent with the more reliable experimental data.

Item Type:Article
Additional Information:Thanks to Institute of Physics editor. The definitive version is available at http://www.iop.org The original PDF of the article can be found at Journal of Physics : Condensed Matter website : http://www.iop.org/EJ/journal/JPhysCM
Audience (journal):International peer-reviewed journal
Uncontrolled Keywords:
Institution: Université de Toulouse > Institut National Polytechnique de Toulouse - INPT
Université de Toulouse > Université Paul Sabatier-Toulouse III - UPS
French research institutions > Centre National de la Recherche Scientifique - CNRS
Other partners > Université Mouloud Mammeri Tizi Ouzou - UMMTO (ALGERIA)
Laboratory name:
Statistics:download
Deposited By: Celine Cabaup
Deposited On:06 May 2009 08:05

Repository Staff Only: item control page