Silicon carbide nanotubes and nanotubular fibers: Synthesis, stability, structure, and classification |
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Authors: | V V Pokropivnyi P M Silenko |
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Institution: | (1) I. N. Frantsevich Institute of Problems in Materials Science, National Academy of Sciences of Ukraine, Vul. Krzhyzhanovs’kogo 3, 03142 Kyiv, Ukraine |
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Abstract: | Published data on silicon carbide nanotubes (SiC-NT) are analyzed. According to theoretical calculations, single-layer SiC-NTs
do not dissociate, but they have not yet been detected experimentally. According to the experimental data, metastable SiC-NTs
with walls consisting of several layers and nanotube fibers were produced. The optimized structure of single-layer SiC-NTs
was calculated by the RHF/6-31G quantum-chemical method. The possibility of obtaining SiC-NTs by gas-phase chemical deposition
from methyltrichlorosilane in the temperature range of 800–1000 °C was investigated. Nanofibers and polygrained SiC nanotubes
were obtained, but ordinary layer SiC nanotubes were not detected. To remove the inconsistencies it was first proposed to
classify the nanotubes according to the structure of their walls, separating all the SiC-NTs into three types: 1) ordinary
layer nanotubes with rolled layers, similar to carbon nanotubes; 2) polynanocrystalline nanotubular fibers or nanotubes with
walls consisting of linked differently oriented nanograins; 3) monocrystalline synthetic nanotubes with ideal crystalline
walls. It was concluded that the ordinary SiC-NTs of the first type are unstable with the exception of one-or two-layer nanotubes;
stable SiC-NTs of the first type and SiC-NTs of the third type have not yet been discovered; only nanotubular fibers of the
second type were obtained experimentally.
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Translated from Teoreticheskaya i éksperimental’naya Khimiya, Vol. 42, No. 1, pp. 3–13, January–February, 2006. |
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Keywords: | nanotube nanofiber nanotubular fiber silicon carbide SiC |
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