Investigation of nanoporous carbon powders produced by high energy ball milling and formation of carbon nanotubes during subsequent annealing

Nanoporous structure was found in graphite samples after ball milling at ambient temperature. The internal micropore surface area, as determined using the T-plot method, was found to vary during milling, in association with phase transformations of the graphite. Structural changes from hexagonal to turbostratic, and to amorphous phases were observed and investigated using X-ray diffraction analysis and transmission electron microscopy. Carbon nanotubes were obtained by the annealing of the milled samples at 1400°C for 6 hours in nitrogen gas.