Preparation, Morphology, and Growth Mechanism of Carbon Nanocoils

Carbon nanocoils with a coil diameter of 50–450 nm were prepared by the catalytic pyrolysis of acetylene, and the preparation conditions and morphology were examined. To clarify the growth mechanism, the carbon nanocoils were also heat treated at 2500 °C for 8 h in a N2 atmosphere, then partially oxidized in air at 600 °C for 15 min. The carbon nanocoils could be grown at 740–770 °C either by applying a magnetic field to the reaction zone or by using sputtered thin films of Au or Au/Ni as a catalyst. Carbon nanocoils are generally single coils, while carbon microcoils are generally double coils. There are two kinds of nanocoils with differing microstructures. One is formed from a carbon fiber with a double microstructure of thin core fiber and clad, while the other is formed from a fiber with a “herring-bone” structure.