关键词: 碳纳米管, 交流放电, 碳纳米胶囊, 碳锥形管, 碳环管

Abstract: V arious forms of nanotubes were produced by AC arc discharge method at a low He pressure. Because the two graphite electrodes we used have the same diameter, there was no deposit formed on the end of the cathode. This is a significant difference from the conventional DC method used to form carbon nanotubes. Some forms of nanotubes different from those reported were found in the soot(but not the cathode deposit). They were the carbon nanocapsule, carbon cone-shaped nanotube and the carbon toroidal nanotube. The nanocapsule has a length-diameter ratio below the conventional nanotubes. The cone nanotube has a cone shape. The toroidal nanotube has a shape like a tire. These novel products were found in the soot. Their formation may arise from the periodic alternantion of the current we used. The difference of the formation mechanisms between AC arc discharge and DC arc discharge were discussed.

Key words: Carbon nanotube, AC arc discharge, Carbon nanocapsule, Carbon cone-shaped nanotube, Carbon toroidal nanotube