Abstract Submitted to the NANOTUBE'02 Workshop:

Last year we presented a new synthesis route for single wall nanotubes (SWNT) based on a plasma torch. In this technique, a gaseous mixture of argon, ethylene and ferrocene is passed through an atmospheric plasma. The plasma dissociates the molecules, and in the exhaust of the plasma flame, the atoms recombine to form SWNT, which are deposited downstream. The drawback of this plasma torch is the formation of carbon deposits in the plasma tube which extinguish the plasma jet after 15 minutes. After a major modification in the design of the process, it is now possible to grow SWNT continuously, with a production rate of 100 mg/min of deposit containing a good proportion of SWNT. The purity of the samples is comparable to catalytic carbon arc. Scanning electron microscopy (SEM), high resolution transmission electron microscopy (HR-TEM) and Raman spectroscopy were used to study samples taken from these deposits. The analyses indicate that the deposits are made up of SWNT, with diameters ranging from 1 to 1.5 nm, and catalyst nanoparticles coated with graphitic layers. Finally, it is possible to control the temperature and the temperature gradient during the growth in order control the diameter of the tubes and also to optimize the SWNT proportion in the sample.