Regensburg 2010 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 75: Nanotribology II
O 75.6: Vortrag
Donnerstag, 25. März 2010, 16:15–16:30, H36
Oxygen-induced degradation of carbynoid structures on carbon surfaces: a DFT study — •Gianpietro Moras1,2, Lars Pastewka1, Peter Gumbsch1,2, and Michael Moseler1,3 — 1Fraunhofer Institut für Werkstoffmechanik, Freiburg (Germany) — 2Universität Karlsruhe, Institut für Zuverlässigkeit von Bauteilen und Systemen, Karlsruhe (Germany) — 3Albert-Ludwigs Universität Freiburg, Physikalisches Institut, Freiburg (Germany)
Carbynoid structures - sp-bonded carbon chains - have recently gained in importance in materials science as they have been reported to form during the growth of diamond-like carbon and nanostructured carbon films, as well as during diamond polishing. The interaction of these structures with air is crucial to the final structure of the deposited or polished surfaces. In particular, oxygen was found to cause the degradation of carbynoid strutures. This may play an important role in the wear mechanism of the diamond polishing.
Here we present a DFT study of the oxidation mechanisms of carbynoid structures. Due to the lack of reference experimental studies specifically devoted to the oxidation mechanisms of supported carbon chains, the accuracy of our simulations is assessed by studying the oxidation of small cationic carbon cluster in the gas phase, for which detailed experimental data exist. This allows us to gain insight into unclear oxidation mechanisms of cyclic cationic carbon clusters. Moreover, the extension of our simulation approach to supported linear carbon clusters yields possible mechanisms for the oxygen-induced degradation of such structures.