A rapid thermal annealing process is demonstrated for defect reduction of multiwalled carbon nanotubes (MWCNTs) using a DC vacuum arc discharge system. The MWCNTs grown by chemical vapor deposition at a relatively low temperature (~650 °C) have structural imperfections which can be thermally annealed to reconstruct the graphitic structure. A vacuum arc discharge system was used to generate high temperatures (~ 1800 °C) followed by rapid cooling. The MWCNTs were rapidly annealed in this system by several cycles of fast heating (300 °C per sec.) and cooling (100 °C per sec.). The annealed samples were characterized by Raman spectroscopy and transmission electron microscopy. It was found that the defect density was reduced effectively by rapid thermal anneal. When inlet water vapor to the annealing chamber, the more defects were removed which indicate the oxygen may play an important role in combustion of the imperfect structures and removing the weakly bonded defects during the rapid heating cycles. After breaking the week bonds, the graphene shell was then reconstructed during the cooling process to produce multi-shell perfection. This method produces effective defect reduction of the MWCNTs.
Journal: TechConnect Briefs
Volume: 1, Nanotechnology 2008: Materials, Fabrication, Particles, and Characterization – Technical Proceedings of the 2008 NSTI Nanotechnology Conference and Trade Show, Volume 1
Published: June 1, 2008
Pages: 122 - 124
Industry sector: Advanced Materials & Manufacturing
Topics: Carbon Nano Structures & Devices