GROWTH MORPHOLOGIES DURING COBALT-CATALYZED SINGLE-SHELL CARBON NANOTUBE SYNTHESIS

We report interesting growth morphologies produced during the electric arc-discharge between a graphite cathode and a composite cobalt-graphite anode, which includes the abundant formation of single-shell carbon nanotubes of 1-2 nm diameter. As the pressure inside the chamber and the cobalt content of the electrode are varied these ''carbon monotubes'' are formed in bundles and in high density under certain conditions in the soot, webs and string-like structures that decorate the chamber and also on a collaret that forms around the conventional deposit containing multi-shell nanotubes. We present high-resolution transmission electron microscopy images of these structures and propose conditions that promote single-tube growth. We also notice, in some cases, novel formation of regularly spaced cobalt particles enclosed in graphitic capsules and surrounded by sheaths of soot.