STRUCTURE AND GROWTH THERMODYNAMICS OF CARBON TABES

Carbon tubes were prepared by Ni (or Ti) catalytic pyrolysis of acetyl ene. The catalytic effect of nanometer nickel powders is related to th e reduction temperature in H-2 atmosphere. Nanometer nickel powders re duced at high temperature have a distinguished catalytic effect, and t he yield of the carbon tubes is relatively high; but for the nickel po wders reduced at low temperature, the yield of carbon tubes is low, an d no tube can be formed. Carbon tubes can only be grown along the edge s or on the tips of the Ni (or Ti) sheets reduced at about 770 degrees C. But if Ni (or Ti) sheets are etched in acid, at lot of carbon tube s with various forms can be formed on their surface. The structure and morphology of the carbon tubes is studied, and the growth thermodynam ics for the straight, curved and helical carbon tubes are systematical ly investigated for the first time.