A novel method for synthesis of carbon nanotubes: Low temperature solid pyrolysis
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A novel method for synthesis of carbon nanotubes: Low temperature solid pyrolysis Y. L. Li Department of Micro-Crystalline & Laser Processing, Chinese Academy of Sciences, 72 Wenhua Road, Shenyang 110015, China
Y. D. Yu Laboratory of Atomic Imaging of Solids, Institute of Metal Research, Chinese Academy of Sciences, 72 Wenhua Road, Shenyang 110015, China
Y. Liang Department of Micro-Crystalline & Laser Processing, Chinese Academy of Sciences, 72 Wenhua Road, Shenyang 110015, China (Received 9 July 1996; accepted 5 March 1997)
We report a novel method for the synthesis of carbon nanotubes: low temperature solid pyrolysis. By pyrolysis of hexamethyldisilazane-derived silicon carbonitride powders in a graphite furnace, we synthesized carbon nanotubes at 1400 ±C. This new method has advantages of in situ growth of the carbon nanotubes, is stable in the synthesis process, and is technically simpler than conventional arc-discharge methods.
Recent interest in the helical structure1,2 of onedimensional nanostructured carbon, namely carbon nanotubes, and their unique physical and chemical properties3,4 has stimulated extensive studies of their synthesis.5–15 The conventional method for producing carbon nanotubes is based on arc-discharge, in which a graphite electrode is evaporated at high temperature (2500–3700 ±C) and the carbon nanotubes are deposited on cathodes.5–8 Modification of the process has been made by adoption of metal-graphite mixed electrode11,12 and different system gases10 aimed at elevating the yield and stabilizing the process. However, since a very high temperature is generated in the arc-discharge, this process is less stable16,17 and is also energy consuming and yield limited. An alternative route, which is reported recently, is catalytic vapor growth in which carbon nanotubes are grown by the decomposition of carboncontaining gases such as acetylene,13 benzene,14 and mixtures of phenylacetylene and thiophene.15 But the presence of metallic catalysts is required for the growth of carbon nanotubes in the vapor growth method and the addition of metallic catalysis may result in contamination of the products. Solid pyrolysis is a main route for vapor-solid (VS) growth of inorganic whiskers, and various whiskers can be grown at pyrolysis temperatures slightly lower than the melting (or decomposition) point of the corresponding bulk materials18 since an appropriate vapor concentration for the whisker growth is attained at these conditions. Conventional solid pyrolysis is technically simple and easily scaled up, which is attractive for the bulk synthesis of carbon nanotubes. In fact, the formation of carbon nanotubes in the arc-discharge is 1678
http://journals.cambridge.org
J. Mater. Res., Vol. 12, No. 7, Jul 1997
Downloaded: 02 Mar 2015
intrinsically a vapor-solid (VS) growth process, which is similar to the VS growth of inorganic whiskers. The difference between the process is that, for the refractory carbon, a high temperature is required to be generate
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