IOP PUBLISHING NANOTECHNOLOGY Nanotechnology 21 (2010) 095705 (5pp) doi:10.1088/0957-4484/21/9/095705 Ignition and temperature behavior of a single-wall carbon nanotube sample O Volotskova 1 , A Shashurin 1 , M Keidar 1 , Y Raitses 2 , V Demidov 3,4 and S Adams 3,4 1 Department of Mechanical and Aerospace Engineering, George Washington University, Washington, DC 20052, USA 2 Princeton Plasma Physics Laboratory, Princeton, NJ 08543-0451, USA 3 Air Force Research Laboratory, WPAFB, Dayton, OH 45433, USA 4 Department of Physics, West Virginia University, Morgantown, WV 26506-6315, USA Received 16 September 2009, in final form 24 December 2009 Published 4 February 2010 Online at stacks.iop.org/Nano/21/095705 Abstract The electrical resistance of mats of single-wall carbon nanotubes (SWNTs) is measured as a function of mat temperature under various helium pressures, in vacuum and in atmospheric air. The objective of this paper is to study the thermal stability of SWNTs produced in a helium arc discharge in the experimental conditions close to natural conditions of SWNT growth in an arc, using a furnace instead of an arc discharge. For each tested condition, there is a temperature threshold at which the mat’s resistance reaches its minimum. The threshold value depends on the helium pressure. An increase of the temperature above the temperature threshold leads to the destruction of SWNT bundles at a certain critical temperature. For instance, the critical temperature is about 1100 K in the case of helium background at a pressure of about 500 Torr. Based on experimental data on critical temperature it is suggested that SWNTs produced by an anodic arc discharge and collected in the web area outside the arc plasma most likely originate from the arc discharge peripheral region. (Some figures in this article are in colour only in the electronic version) 1. Introduction The unique thermal, mechanical and electrical properties of single-wall nanotubes (SWNT) can be potentially useful for many applications ranging from nano-electronics to biology [1–5]. Most of these applications require knowledge of the thermal and electrical limitations of SWNTs. Thermal stability of SWNTs was studied in recent works [6–10]. Destruction of SWNTs under various treatments (laser [6], electric current [7], photoflash [8, 14], heater [10] and microwave [9]) was observed at some critical temperature (T cr ) and accompanied by morphology changes. The spread of T cr values reported in these works was quite substantial. For instance, it has been reported [11] that SWNTs with diameters of 0.4 nm were stable up to 730 K in vacuum, but underwent significant structural modifications with heating to higher temperatures, including a transition to an amorphous- carbon-like structure at about 870 K. A different situation was obtained for 1.36 nm diameter SWNTs, which remained stable in vacuum up to 1700 K [7]. Another study reported that, in air, the ignition of SWNTs with diameters ∼0.8–10 nm involved oxidization processes leading to their complete destruction at temperatures of about 1100 K [12, 13]. Lower ignition temperatures of about 750 and 660 K have also been reported elsewhere [6, 14]. In the case of inert gas environments (argon, helium) near atmospheric pressure, SWNT bundles were reported to not be damaged up to 1800 K [8, 10, 15] while a further increase of temperature led to the coalescence of SWNTs. The large discrepancy in the observed temperatures for SWNT destruction can be explained by the different diameters of nanotubes [13]. It has been argued [10] that small- diameter SWNTs (∼0.4–0.8 nm) are more unstable thermally than their larger counterparts due to a stronger curvature effect and higher strain in the small nanotubes. Electrical properties of SWNTs are also strongly depen- dent on their geometry through the curvature effect [1, 16]. In fact, a strong curvature effect in small-diameter SWNTs results in hybridization of σ and π orbitals, leading to a significant change of electrical properties. Another parameter strongly af- fecting electrical properties of nanotubes is the temperature. A ‘V-shaped’ dependence of the resistivity of SWNT samples on temperature with predominantly metallic nanotubes has been 0957-4484/10/095705+05$30.00 © 2010 IOP Publishing Ltd Printed in the UK 1