The growth patterns and morphologies of carbon micro-coils produced by chemical vapor deposition

Carbon micro-coils with coil diameters of micron orders were obtained by th e Ni-catalyzed pyrolysis of acetylene containing a small amount of thiophen e impurity. The effect of reaction conditions on the growth patterns and mo rphologies of the carbon coils were examined in detail. The cal bon coils w ith very regular and small coils diameter of about 5 mu m, regular coil pit ches, and a coil length of >8 mm, could be obtained with the maximum coil y ield of about 20 mg/cm(2)-substrate, and the maximum thickness of coil laye rs of about 8 mm under optimum reaction conditions. The coil pitch and coil diameter could be controlled by controlling the gas flow rate and ratio, a nd the reaction temperature. The carbon coils prepared by different reactio n times from the initial to 2 h or more can be vividly described as 'embryo coils', sprout coils, short coils and long coils with increasing reaction time. (C) 1999 Elsevier Science Ltd. All rights reserved.