Ignition and temperature behavior of a single-wall carbon nanotube sample.

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.