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Teoret. i eksperim. khimiya. 2006. Vol.42 No. 1. p. 3-13

Silicon Carbide Nanotubes and Nanotubular Fibers:
Synthesis, Stability, Structure and Classification

 

V. V. Pokropivny, P. M. Sylenko


I. N. Frantsevich Institute for Problems of Materials Science, National Academy of Sciences of Ukraine
Vul. Krzhyzhanivskogo 3, 03142 Kyiv, Ukraine. E-mail: pokr@ipms.kiev.ua


The literature data about SiC nanotubes (SiC-NT) were analyzed. In accordance with theoretical calculations single-wall SiC-NTs do not destroy while they have not been observed experimentally yet. In acordance with experimental data metastable several-layer SiC-NTs were obtained as well as nanotubular fibers. The optimized structure of single-wall SiC-NTs was calculated by quantum chemistry RHF/6-31G method. The possibilities to obtain SiC-NTs by chemical vapour deposition from methylthreechlorsilane in the themperature range 800-1000 oC were studied. Nano-whiskers and poly-nano-grained nanotubes of Si were obtained, but usual layered SiC nanotubes were not found. To cancel inconsistencies all SiC nanotubes in dependence of their wall structure are suggested to classify under three types: 1) layered usual NTs with rolled layers; 2) polynanocrystalline nanotubular fibers or NTs the walls of which consist of linked nanograines; 3) monocrystalline artifical NTs with perfect crystalline walls. It was concluded that usual SiC-NTs of the 1st type are metastable except for one- or two-layer NTs; stable SiC-NTs of the 1st kind and SiC-NTs of the 3rd kind were not found so far; only nanotubular fibers of the 2nd kind were obtained experimentally.


Key word nanotube, nanofiber, nanotubular fiber, silicon carbide, SiC.