Submonolayers of carbon on alpha-Fe facets: An ab initio study
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© 2010 American Physical Society (APS). This is the accepted version of the following article: Riikonen, S. & Krasheninnikov, A. V. & Nieminen, Risto M. 2010. Submonolayers of carbon on alpha-Fe facets: An ab initio study. Physical Review B. Volume 82, Issue 12. 125459/1-13. ISSN 1550-235X (electronic). DOI: 10.1103/physrevb.82.125459, which has been published in final form at http://journals.aps.org/prb/abstract/10.1103/PhysRevB.82.125459.
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School of Science |
A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä
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Date
2010
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Mcode
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Language
en
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125459/1-13
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Physical Review B, Volume 82, Issue 12
Abstract
Motivated by recent in situ studies of carbon nanotube growth from large transition-metal nanoparticles, we study various α-iron (ferrite) facets at different carbon concentrations using ab initio methods. The studied (110), (100), and (111) facets show qualitatively different behavior when carbon concentration changes. In particular, adsorbed carbon atoms repel each other on the (110) facet, resulting in carbon dimer and graphitic material formation. Carbon on the (100) facet forms stable structures at concentrations of about 0.5 monolayer and at 1.0 monolayer this facet becomes unstable due to a frustration of the top-layer iron atoms. The stability of the (111) facet is weakly affected by the amount of adsorbed carbon and its stability increases further with respect to the (100) facet with increasing carbon concentration. The exchange of carbon atoms between the surface and subsurface regions on the (111) facet is easier than on the other facets and the formation of carbon dimers is exothermic. These findings are in accordance with a recent in situ experimental study where the existence of graphene-decorated (111) facets is related to increased carbon concentration.Description
Keywords
carbon nanotubes, growth, nanoparticles, iron
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Citation
Riikonen, S. & Krasheninnikov, A. V. & Nieminen, Risto M. 2010. Submonolayers of carbon on alpha-Fe facets: An ab initio study. Physical Review B. Volume 82, Issue 12. 125459/1-13. ISSN 1550-235X (electronic). DOI: 10.1103/physrevb.82.125459.