Generation of curved or closed-shell carbon nanostructures by ball-milling of graphite

Curved or closed-shell carbon nanostructures were produced by ball-milling of graphite. A high resolution indicates that the ball-milling not only produces bend of graphite sheets, forming carbon nanoarches, but also produces closed-shell carbon nanostructures, nearly carbon 'onions'. The possible formation mechanism is proposed. (C) 2000 Elsevier Science B.V. All rights reserved.