2006 Fiscal Year Final Research Report Summary
A theoretical study and simulation on current-limit of carbon nanotubes
| Project/Area Number |
17510092
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Nanostructural science
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| Research Institution | Waseda University |
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Principal Investigator |
MATSUNAGA Yasushi Waseda University, Faculty of Science and Engineering, Associate Professor (70277838)
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| Project Period (FY) |
2005 – 2006
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| Keywords | carbon nanotubes / Landau mode / induced-magnetic field / electrical breakdown |
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| Research Abstract |
At the first half, we estimated the optimum electric field at the sheath edge and the minimum interval among nanotubes to promote the growth of armchair-type nanotubes(metallic character) as a function of the nanotube length. On the basis of the electric charge distribution in a nanotube and the optimum electric field at the tip of a nanotube evaluated using the Huckel-Poisson method, we calculated the structure of the electric field lines outside a nanotube in the sheath region. To maintain the chemical activity at the tip, the sheath electric field must be decreased. We showed the decreasing rate of the sheath electric field with respect to the nanotube length.
On the basis of the Landau quantization, the bound state is discussed, which includes the finite length effect, induced-magnetic field, and electric field in a current-carrying nanotube. Using a slab model and evaluating the matching of the wave function in the radial direction, the authors obtained the conditions of a Landau mode in which the momentum in the axial direction is reversed in the outer side and inner side of the nanotube shell. The mode arises over a threshold electric current and influences more long tubes than short tubes. We compared the theoretical results with the experimental data, estimating the minimum voltage condition, the relations between the tube length and the current for the obtained Landau mode, and the tube length and current data in the experiments. It is plausible that the Landau mode plays an important role in the eventual electrical breakdown and the thinning phenomena. The wave function broadly spreading in the outer side in the radial direction activates the air and triggers the destruction of atomic bonds. Another factor influencing the electrical breakdown phenomena was found.
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