Regensburg 2010 – wissenschaftliches Programm
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MM: Fachverband Metall- und Materialphysik
MM 26: Poster Session
MM 26.31: Poster
Dienstag, 23. März 2010, 14:45–16:30, Poster C
Aggregation of carbon in a H2 atmosphere investigated by ReaxFF-molecular dynamics simulations — •Norbert Lümmen — University of Bergen, Department of Physics and Technology, Allégaten 55, 5007 Bergen, Norway
Controlled manufacturing of very pure carbon nanoparticles (Carbon Black) can be achieved by, for example, thermal decomposition of gaseous precursors like acetylene or methane. A large quantity of molecular hydrogen is produced during the decomposition process.
We have investigated the aggregation process of carbon molecules and hydrocarbons from carbon atoms in an atmosphere of H2 at different temperatures, densities and initial amount of H2 by molecular dynamics (MD) simulations. The calculation of interatomic forces within the MD-simulations was based on the Reax Force Field (ReaxFF).1
The growth of molecules and their compositional changes were followed up to 4 ns of simulation time. The developing number of ring structures based on carbon atoms was analysed by the shortest-path ring method.2 Formation of carbon catenates and hydrocarbons of different sizes was observed. A decreasing amount of initial H2 allows the aggregation of pure carbon molecules up to 30 atoms. Hydrogen atoms are found along and at the ends of these carbon chains in all types of systems. These linear molecules eventually aggregate to larger ones in which networks of rings of carbon atoms can be found.
[1] van Duin et al., J. Phys. Chem. A 105, 9396 (2001).
[2] Franzblau, Phys. Rev. B 44, 4925 (1991).