ライブラリ登録: Guest

ISSN Online: 2377-424X

ISBN CD: 1-56700-226-9

ISBN Online: 1-56700-225-0

International Heat Transfer Conference 13
August, 13-18, 2006, Sydney, Australia

CONTROL OF FLAME NANOTUBE SYNTHESIS USING MODERATE ELECTRIC FIELDS: INFLUENCE ON MORPHOLOGY AND BRANCHING PHENOMENA

Get access (open in a dialog) DOI: 10.1615/IHTC13.p11.130
9 pages

要約

A counter-flow oxy-fuel flame coupled with an electric field was demonstrated to control the growth rate and morphology of carbon nanotubes (CNTs) This builds upon our previously reported work using a very small electric field to stimulate the growth of vertically aligned carbon nanotube (VACNT) arrays. Here stronger electric fields results in improved control of alignment and growth rates and give rise to branching phenomen within the CNTs. Scanning electron microscopy (SEM) imaging analysis of the surfaces of the Ni-based catalytic support inserted in the flame showed that increasing the applied voltage increased the thickness of the resulting VACNTs arrays.. Transmission electron microscopy (TEM) illustrated modified morphologies such as Y, T, and multi-junction branching of the multi-walled CNTs. Microscopic analysis of the arrays synthesized at U=−5 Volts illustrated the presence of particle sprouting or early junction formation in the CNTs. Low resolution TEM showed these formations as small bumps extruding from the outer surface of the CNTs. The diameters of the bumps are frequently smaller than the diameter of the nanotube. High-resolution TEM of the bumps revealed them to be composed of an inner metallic material covered with several graphitic layers on its outer surface. Additionally, high-resolution TEM showed the transportation pathway of the catalytic material originating from the inner cavity of CNT to its outer surface. At U=−25 V, fully branched CNT structures were obtained Interestingly the length of the branches sometimes exceeds the length of the stems or trunks