Quantitative evaluation of nanotube content produced by arc discharge in a raw material

The amount of carbon nanotube in a raw material grown by electric arc discharge, ignited in different liquid environments, has been evaluated by combined use of X-ray diffraction, electron microscopy and differential thermal analysis (TG-DTA) in a reactive environment. X-ray diffraction was used to discriminate the various carbon microstructures utilizing the difference in lattice parameter between curved and planar graphite structures. The results are repeatable and in good agreement with TG-DTA measurements carried out in a reactive environment, where the relative amount of carbon nanostructures is evaluated on the basis of the difference in the reaction kinetics with atmospheric oxygen. In analyzed specimens, SEM and TEM show the presence of only two allotropic forms of carbon, namely nanotubes and globular particles, the relative amounts of which depend on the nature of the liquid surrounding the discharge and on the voltage applied to the electric arc.