Preparation of vapor grown carbon fibers by microwave pyrolysis chemical vapor deposition

Vapor grown carbon fibers have been prepared without any catalyst by microwave pyrolysis chemical vapor deposition using CH₄ as source gas and N₂ as carrier gas at 1050-1150 °C. Scanning electron microscopy images reveal that vapor grown carbon fibers are made up of sub-fibers which are hexagonal and layer-like carbon. Polarized light images indicate that sub-fibers are formed by high-texture carbon and surrounded by a thick layer of medium-textured carbon. Raman spectroscopy indicates that the as-prepared vapor grown carbon fibers exhibit relatively high degree of graphitization. Also, the broadening of the “graphite” peaks observed in the X-ray diffraction pattern, as well as the intensity ratio value of ID/IG of the D- and G-band obtained from Raman spectroscopy, indicate the existence of a large quantity of defects in the vapor grown carbon fibers. Moreover, no impurity is observed by the X-ray diffraction pattern.