There is today an interest to understand the growth mechanism of single-wall carbon nanotubes, SWCNT, produced by the catalytic chemical vapour deposition technique. In the production carbon containing feedstock as carbon monoxide, methane, acetylene, alcohol will react on the surfaces of 1-2 nm metal particles of Fe, Co, Ni and produce carbon atoms, which will diffuse on the metal cluster surface or dissolve in the clusters.[1]
We have in a number of calculations [2-4] used classical molecular dynamics methods, MD, for simulation of the growth of this kind of SWCNT using different model potentials or semi-empirical potential energy surfaces, PES. The effects of substrates on metal clusters have also been investigated using a Lennard Jones potential, which has also been fitted to results from DFT calculations of deposited clusters.
The simulations show that the liquid to solid phase transition of the metal clusters is strongly dependent on the particle size and smaller clusters <1.5 nm are liquid at typical vapour deposition temperature of 800-1500 K, whereas larger clusters > 5 nm are solid.
References:
1. H. Dai, Acc. Chem. Res, 35, 1035 (2002)
2. F. Ding, K. Bolton and A. Rosén, J. Phys.Chem B108, 17369-17377 (2004).
3. K. Bolton, F. Ding and A. Rosén, J of Nanoscience and Nanotechnology 6, 1211-1224 (2006)
4. F. Ding, K. Bolton, and A. Rosén, Appl. Surface Science, 252, 5254-5258 (2006)
5. F. Ding, A. Rosén, S. Curtarolo and K. Bolton, Appl. Phys. Lett. 88, 133110 (2006)
Funding by The Swedish Research Council and the Swedish Foundation for Strategic Research and Honda Research Institute
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