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Comparative NMR study of new carbon forms

✍ Scribed by Y. Maniwa; M. Sato; K. Kume; M.E. Kozlov; M. Tokumoto

Publisher
Elsevier Science
Year
1996
Tongue
English
Weight
517 KB
Volume
34
Category
Article
ISSN
0008-6223

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✦ Synopsis

A comparative

13C-NMR study of several new phases of pressure/temperature-treated C,,, a bundle of carbon nanotubes, graphite and diamond was carried out in the 4-300 K temperature range. It was found that face-centered cubic and rhombohedral high-pressure phases of C, reveal very unusual NMR lines at 110 and 70 ppm, respectively, shifted from that of pristine C, (143 ppm). These lines disappear in a hard carbon phase prepared by compression of Cm at more severe conditions. Comparison with NMR spectra of pristine C,,, diamond and graphite showed that the fullerenes acquire some partial sp3 character when they are pressure-treated at 3-4.6 GPa and various temperatures (720°C). However they are apparently not transformed into four-fold-coordinated diamond-like carbon clusters. NMR spectra of carbon nanotubes exhibited an anomalous shift which may be attributed to their cylindrical geometry.

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