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Highly uniform multiwall carbon nanotubes (MWCNTs) were synthesized using templ ate confining growth technique in combination with high temperature annealing. Scanning electron microscopy (SEM) images show that the morphology and dimensi on of raw carbon nanotubes (CNTs) synthesized by template confining growth techn ique is completely controlled by the template structure. Transmission electron m icroscopy (TEM) and x-ray powder diffraction (XRD) studies reveal that the tube wall has a mixed structure of amorphous carbon and graphite nanocrystallites. To reduce crystallite defects and the content of amorphous carbon, a series of hig h temperature annealing (1100—2400℃) of the raw CNTs were carried out. In addi tion, the tube wall crystallization behavior under high temperature was prelimin arily studied. The experiment results show that high temperature annealing is an effective way to improve the quality of MWCNTs.

Structural phase transformation from multiwalled carbon nanotubes to nanocr ystalline diamond by hydrogen plasma posttreatment was carried out. Ultrahigh equivalent diamond nucleation density above 1011 nuclei/cm2 was easily obtained . The diamond formation and growth mechanism was proposed to be the consequence of the formation of sp3 bonded amorphous carbon clusters. The hydrogen chemi so rption on curved graphite network and the energy deposited on the carbon nanotu bes by continuous impingement of activated molecular or atomic hydrogen are resp onsible for the formation of amorphous carbon matrix. The diamond nucleates and grows in the way similar to that of diamond CVD processes on amorphous carbon films. The present method of hydrogen treatment provides a controllable way for the CVD of high quality diamond films.