Diffusion-gradient-induced length instabilities in the catalytic growthof carbon nanotubes

We report in situ transmission electron microscopy observations of length instabilities in the growth of straight-wall carbon nanotubes. The nanotubes are grown at: T < 725 ° C , P < 80 mTorr by chemical vapor decomposition of acetylene on Fe nanoparticles formed in situ prior to tube growth. The growing nanotubes detach episodically from the catalyst particles, which then nucleate a fresh nanotube. Detachment is induced by the shedding of carbon-starved inner walls during diffusion-limited growth.