Beaded carbon tubes

Unusual tubular carbon structures were observed when preparing carbon tubes using a vapor phase process. Regular, single-diametered carbon tubes were obtained at temperatures below 1300 degrees C. However, at temperatures gre ater than 1300 degrees C, in addition to regular carbon tubes, beaded carbo n tubes appeared. The occurrence and appearance of such unusual beaded stru cture is thought to be related to the growth temperature, and is explained in terms of a three-dimensional nucleation model. (C) 1999 American Institu te of Physics. [S0003-6951(99)03247-7].