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Carbon nanotube synthesis in a flame using.pdf

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DOI: 10.1007/s00339-003-2196-3 Appl. Phys. A 77, 885–889 (2003) Materials Science Processing Applied Physics A r.l. vander wal1, g.m. berger1 t.m. ticich2 Carbon nanotube synthesis in a flame using laser ablation for in situ catalyst generation 1 NCMR, c/o NASA–Glenn Research Center, M.S. 110–3 21000, Brookpark Rd., Cleveland, OH 44135, USA 2 Centenary College of Louisiana, Dept. of Chemistry, 2911 Centenary Blvd., Shreveport, LA 71134, USA Received: 4 November 2002/Accepted: 2 April 2003 Published online: 8 July 2003 ? ? Springer-Verlag 2003 ABSTRACT Laser ablation of either Ni or Fe is used to create nanoparticles within a reactive flame environment for catalysis of carbon nanotubes (CNTs). Ablation of Fe in a CO-enriched flame produces single-walled nanotubes, whereas, ablation of Ni in an acetylene-enriched flame produces carbon nanofibers. These results illustrate that the materials for catalyst particle formation and CNT, SWNT or nanofiber, inception and growth in the aerosol phase can be supplied from separate sources; a metal-carbon mixture produced by condensation is not neces- sary. Both particle formation and CNT inception can begin from molecular species in a laser-ablation approach within the com- plex chemical environment of a flame. Moreover, SWNTs and nanofibers can be synthesized within very short timescales, of the order of tens of milliseconds. Finally, high-intensity pulsed laser light can destroy CNTs through either vaporization or co- alescence induced by melting. PACS 42.62 Fi; 81.05.Tp; 82.80.Ch; 81.15 Fg 1 Introduction Although single-walled nanotubes (SWNTs) were initially discovered within an arc discharge [1], researchers rapidly turned to laser ablation of metal–graphite compos- ite targets within high-temperature tube furnaces for their synthesis [2]. In the laser-ablation–furnace approach, a laser pulse creates a superheated plasma consisting of carbon and metal species from the composite target. The high- temperature furnace slows t
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