Ammonia sNH3d gas was thought to be essential for the growth of vertically aligned multiwalled
carbon nanotubes sVA-MWCNTsd and led to the formation of bamboo-like structures. Here, we
show that VA-MWCNTs with ideal tubular structures can be grown on substrates by various mixed
gases with or without NH3 gas. The growth of these VA-MWCNTs is guided by a growth model that
combined the dissociative adsorption of acetylene molecules sC2H2d and the successive
vapor-liquid-solid growth mechanism. Results indicate that the key factor for growing these
VA-MWCNTs is a balance between the decomposition rate of the C2H2 molecules on the iron
catalyst and the subsequent diffusion and segregation rates of carbon.
© 2005 American Institute of Physics. fDOI: 10.1063/1.1952575g