Single-wall and multiwall carbon nanotubes are currently the subject of an
intense research effort owing to the outstanding properties they may posses
s. Many synthesis methods have been proposed, most of which involve nanomet
ric metal particles. In this article the various mechanisms proposed for na
notube nucleation and growth from such particles have been reviewed. The mi
cro/nanostructure of the materials obtained by the different methods have a
lso been addressed.