Liquid Carbon, Carbon-Glass Beads, and the Crystallization of Carbon Nanotubes
Walt A. de Heer,1*
Philippe Poncharal,2
Claire Berger,3
Joseph Gezo,4
Zhimin Song,1
Jefferson Bettini,5
Daniel Ugarte5,6
The formation of carbon nanotubes in a pure carbon arc in a
helium atmosphere is found to involve liquid carbon. Electron
microscopy shows a viscous liquid-like amorphous carbon layer
covering the surfaces of nanotube-containing millimeter-sized
columnar structures from which the cathode deposit is composed.
Regularly spaced, submicrometer-sized spherical beads of amorphous
carbon are often found on the nanotubes at the surfaces of these
columns. Apparently, at the anode, liquid-carbon drops form,
which acquire a carbon-glass surface due to rapid evaporative
cooling. Nanotubes crystallize inside the supercooled, glass-coated
liquid-carbon drops. The carbon-glass layer ultimately coats
and beads on the nanotubes near the surface.
2 Université Montpellier 2 GDPC, Place Eugène Bataillon 34095 Montpellier, Cedex 5, France.
3 CNRS-LEPES, BP 166, 38042 Grenoble, Cedex 9, France.
4 University of Illinois at Urbana-Champaign, Department of Physics, 1110 West Green Street, Urbana, IL 61801, USA.
5 Laboratório Nacional de Luz Síncrotron, Caixa Postal 6192,13084-971 Campinas SP, Brazil.
6 Instituto de Física Gleb Wataghin, Universidade Estadual de Campinas, Caixa Postal 6165, 13083-970 Campinas SP, Brazil.
* To whom correspondence should be addressed. E-mail: walt.deheer{at}physics.gatech.edu
