AVS 49th International Symposium
    Plasma Science Wednesday Sessions
       Session PS+NT-WeM

Invited Paper PS+NT-WeM3
Efficient Production of Single-Wall Carbon Nanotubes by Means of the Gravity-free Gas Arc Dischargee

Wednesday, November 6, 2002, 9:00 am, Room C-103

Session: Plasma Science and Technology for Nanostructures
Presenter: T. Mieno, Shizuoka University, Japan
Authors: T. Mieno, Shizuoka University, Japan
M. Kanai, University of London, UK
H. Shinohara, Nagoya University, Japan
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Single-wall carbon-nanotube (SWNT) are attracting much attention by their unique structures and properties, and applications of nanotubes are demonstrated as a cold electron emitter, strong wire, electronic devices and hydrogen absorber. The SWNT are produced by the gas-arc method as same as the fullerene production method. A carbon anode mixed with metal catalyst is arc sublimated in He gas (p> 40 kPa), and high density carbon particles deposit on metal particles in hot gas atmosphere making nano-pipe structures, diameter of which is about 1 nm. As these nanotubes, metal particles and another carbon clusters are flown up by the heat convection, the reaction time is limited by this heat convection. If the heat convection is suppressed by the gravity-free condition, diffusion speed of these particles is suppressed and longer reaction time can be expected.@footnote 1@ In order to examine this gravity effect, the 12m-high vertical swing tower@footnote 1@ is used and the carbon nanotubes are produced in the gravity-free condition.@footnote 2@ Integrated gravity-free sublimation time is about 14 min. After the discharge, the carbon soot is collected and its weight is measured. As a result, production rate of the carbon soot including SWNT about 7 times increase in the gravity-free condition compared with that of the normal gravity condition. By the TEM (microscope method) their morphology is observed and more (about 2 times) dense bundle of SWNT is confirmed in the gravity-free condition. Thickness of the produced nanotube is measured by the Raman scattering method, and fatter nanotube (mainly d= 1.4 nm) is produced in the gravity-free condition compared with the normal-gravity case. @FootnoteText@@footnote 1@ T. Mieno, Jpn. J. Appl. Phys. 37 (1998) L761. @footnote 2@M. Kanai, T. Mieno, H. Shinohara et al, Appl. Phys. Lett. 79 (2001) 2967.