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International Heat Transfer Conference 15

ISSN: 2377-424X (online)
ISSN: 2377-4371 (flashdrive)

Mass Spectroscopy of Intermediate Products Involved in Chemical Vapor Deposition Synthesis of Carbon Nanotube

Shuhei Inoue
Hiroshima University

Daisuke Nakahara
Department of Mechanical Science and Engineering, Hiroshima University

Yosuke Oga
Department of Mechanical Science and Engineering, Hiroshima University

Yukihiko Matsumura
1Division of Energy and Environmental Engineering, Hiroshima University

DOI: 10.1615/IHTC15.mnf.008586
pages 5037-5045


KEY WORDS: Mass spectrometry, Nano/Micro scale measurement and simulation, carbon nanotube

Abstract

We focused on pyrolysis involved in chemical vapor deposition process of carbon nanotube. So far it was prospected that carbon nanotubes were never synthesized at more than 1000 ????C owing to the degradation and/or polymerization of source gases such as ethanol, methanol, and methane. However there was no experimental evidence; thus, we tried to examine to clarify the reaction mechanism occurred in the process. We employed vacuum furnaces as a reactor and quadrupole mass spectrometer to observe the reactant. The reactor was controlled to be 500 to 1100 ????C and 1.0 ×10-2 to 1.0 ×103 Pa. The reactants were lead into the higher vacuum chamber of 1.0 ×10-3 Pa to avoid from unintentional collision and simultaneously cooled through adiabatic expansion. Thus, it was expected that there were no further reactions after the pyrolysis. As a dominant spectrum, mass number of 28 was observed. This product tends to increase as the temperature increases. At the same time, the G/D ratio, which is used to simply express the purity of single-walled carbon nanotube, also becomes better, so that this product is considered to be the key products. Consequently, this trend keeps on up to 1100 ????C; thus, the reaction itself is considered to be desirable at even higher temperature, at which single-walled carbon nanotube are never synthesized. On the other hand, the melting temperature of catalyst nano particle was estimated to be 950 ????C by molecular dynamics simulation. We consider this fusion results in failure of nucleation.

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