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 the Ni-catalyzed pyrolysis of acetylene containing a small amount of thiophene impurity. The effect of reaction conditions on the growth patterns and morphologies of the carbon coils were examined in detail. The cal bon coils with very regular and small coils diameter of about 5 mu m, regular coil pitches, and a coil length of >8 mm, could be obtained with the maximum coil yield of about 20 mg/cm(2)-substrate, and the maximum thickness of coil layers 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, and the reaction temperature. The carbon coils prepared by different reaction 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.