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-graph ite anode, which includes the abundant formation of single-shell carbo n nanotubes of 1-2 nm diameter. As the pressure inside the chamber and the cobalt content of the electrode are varied these ''carbon monotub es'' are formed in bundles and in high density under certain condition s in the soot, webs and string-like structures that decorate the chamb er and also on a collaret that forms around the conventional deposit c ontaining multi-shell nanotubes. We present high-resolution transmissi on electron microscopy images of these structures and propose conditio ns that promote single-tube growth. We also notice, in some cases, nov el formation of regularly spaced cobalt particles enclosed in graphiti c capsules and surrounded by sheaths of soot.