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.