Y. Shimizu, Y. Moriyoshi, S. Komatsu*, T. Ishigaki*, T. Ikegami*, T.Sato*,and Y. Bando*

College of Engineering, Hosei University, 3-7-2 Kajinocho Koganeishi, Tokyo 184, Japan
bmoriyos@cafe.cc.hosei.ac.jp

*National Institute for Research in Inorganic Materials
1-1 Namiki Tsukuba 305, Japan

B-C-N nanotubes were tried to prepare by a plasma evaporation method. Two raw samples were used for the preparation. One was the sintered body of a mixture of hBN, C, and B2O3 in which C was used in excess of a few mole over the amount of B2O3. The other was porous BC4N which was prepared by heating a mixture of urea, saccharose, and B2O3 at 1500C for 3h in flow of N2. The obtained samples were evaporated to chemical species in the high temperature region of a dc arc plasma flame. The chemical species were condensed as powders to a copper disk cooled with water. The powders on the disk were collected and observed with a scanning electron microscope (SEM), a transmission electron microscope (TEM), and analyzed by electron energy loss spectroscopy (EELS). As a result, it was clarified that the nanotubes with various aspect ratio from 10 to 100 were found. EELS data clearly indicated that no nanotubes with a homogeneous phase consisting of B, C, and N were found, but BN- and carbon-nanotubes, and a carbon nanotube surrounded with BN nanotube were detected. The shape of the nanotube tips were in faceted, conical, open ended, closed ended at both sides, and other. The effects of impurities and temperatures on the preparation of nanotubes were discussed, and also the formation mechanism of the nanotubes obtained was discussed from the viewpoint of the structural analogy between a nanotube and a sample.