INSTITUTE OF PHYSICS PUBLISHING JOURNAL OF PHYSICS D: APPLIED PHYSICS J. Phys. D: Appl. Phys. 39 (2006) 320–326 doi:10.1088/0022-3727/39/2/012 RF thermal plasma processing of fullerenes B Todorovi´ c-Markovi´ c 1 , Z Markovi´ c 1,7 , I Mohai 2 , Z Nikoli´ c 3 , Z Farkas 4 , J Sz´ epv¨ olgyi 2 , ´ E Kov´ ats 5 , P Scheier 6 and S Feil 6 1 ‘Vinˇ ca’ Institute of Nuclear Sciences, POB 522, 11001 Belgrade, Serbia and Montenegro 2 Institute of Materials and Environmental Chemistry, Chemical Research Center, Hungarian Academy of Sciences, POB 17, H-1525 Budapest, Hungary 3 Faculty of Physics, University of Belgrade, POB 316, 11001 Belgrade, Serbia and Montenegro 4 Department of Silicate Chemistry and Materials Engineering, Veszpr´ em University, Egyetem u. 2, H-8200 Veszpr´ em, Hungary 5 Research Institute of Solid State Physics and Optics, Hungarian Academy of Sciences, POB 49, H-1525 Budapest, Hungary 6 Leopold Franzens Universit¨ at Innsbruck, Institut f ¨ ur Ionenphysik, Technikerstr. 25, A-6020 Innsbruck, Austria E-mail: zormark@vin.bg.ac.yu Received 18 July 2005, in final form 8 November 2005 Published 6 January 2006 Online at stacks.iop.org/JPhysD/39/320 Abstract This paper presents results on fullerene formation during the processing of different graphite powders in an RF thermal plasma reactor. Graphite powders of different particle size and purity were fed into the reactor (Aldrich, KS4). Optical emission spectroscopy of atomic and molecular species is used as a diagnostic tool of the RF plasma flame. It was found that rotational and vibrational temperatures of C 2 radicals depend on the feed rate of the precursor used. The volumes of RF plasma flame during processing of graphite powders have been calculated. By analysing scanning electron microscopy micrographs of soot, the evaporation rate of the precursors used has been evaluated as well. Based on the obtained values of volumes of plasma flame and evaporation rate of starting powders, the concentration of C 2 radicals has been calculated. (Some figures in this article are in colour only in the electronic version) 1. Introduction The many potential uses of fullerenes and nanotubes for nano-engineered materials include a possible electronic super/semiconductor, self-aligned electron field emission tips, catalyst cradles for highly selective chemical reactions and a transport medium for medical drug delivery [1, 2]. However, the high price of purified fullerenes has inhibited their widespread use up to now. Fullerenes are usually produced in high-temperature gases such as electric arcs, gases which are produced by resistive heating or flames [3]. All these methods have in common a very low fullerene production capacity. Only a few reports on fullerene synthesis by plasma torch using various carbon powders as precursors have been 7 Author to whom any correspondence should be addressed. published up to now. Yoshie et al has synthesized fullerenes in a hybrid plasma which is characterized by the superposition of an RF plasma and a dc arc jet operated at atmospheric pressure [4]. In Wang’s report, an RF inductively coupled thermal plasma was used to fabricate fullerenes by direct evaporation of C or C–Si mixture powder by high enthalpy of the plasma [5]. Fulcheri et al concluded that plasma technologies are particularly adapted to the production of nanoparticles. Being highly flexible they allow the use of a wide range of carbon feed stock (solid, liquid, gaseous, alone or associated with a catalyst element) access to very high temperatures and enthalpy densities unreachable with conventional combustion processes [6]. Dubrovsky et al synthesized fullerenes by injecting carbon black precursor into a dc plasma torch [7]. 0022-3727/06/020320+07$30.00 © 2006 IOP Publishing Ltd Printed in the UK 320