TEM studies of the initial stage growth and morphologies of bamboo-shaped carbon nanotubes synthesized by CVD

The initial stage.:growth of bamboo-shaped carbon nanotubes (CNTs) synthesized by catalytic decomposition of methane is investigated. A special experimental procedure has been developed to stop the process after short durations (0 s to 3 min). It has found that during the early stages (60 s), carbort cluster-encapsulated nanoparticles are formed. With prolonging synthesis time (3 min), some CNTs coexisted with carbon cluster-encapsulated nanoparticles are formed. HRTEM observations show that these CNTs display multi-walled and bamboo structure and the encapsulated catalytic particles are quasi-cone morphologies. At the same time, the catalytic particles only encapsulated with carbon clusters present quasi-spherc structures. For growth up to 60 min, two kinds of bamboo mode structures are observed: conical, and cylindrical, which are developed by quasi-cone and quasi-sphere catalytic particles, respectively. Moreover, the early stage growth mode of the CNTs is predominantly of the base growth mode according to TEM observations. (c) 2006 Elsevier B.V. All rights reserved.