Takeo Matsui

Growth of amorphous carbon nanotube from poly(tetrafluoroethylene) and ferrous chloride

Abstract The formation process of an amorphous carbon nanotube (α-CNT) from poly-(tetrafluoroethylene) using ferrous chloride was investigated by observing the TEM images of the isolated intermediates and conducting in situ TEM observation of its formation. These observations revealed unique features of the nanotube growth process through a series of steps; the growth of the core whisker, the deposition of amorphous carbon fragments onto the core whisker, and the disappearance of the core whisker, leaving the α-CNT. Such a unique process suggests a new method of controlling the carbon nano structure through the deposition of carbon over the core whisker template. The stable fluoride form of the core whisker is a key to preparing the amorphous carbon wall on its surface.

Carbyne : electrochemical preparation and nanotube formation

Carbyne-like or polyyne-containing carbon was prepared by the electrochemical reduction of PTFE. By heating and electron-beam irradiation in vacuum, carbon nanotubes were formed on the surface of the prepared carbon material. Only when the carbon contains the polyyne structure, were the carbon nanotubes found to be formed. From the view of the formation mechanism, the formation route through polyyne is strongly suggested.

Graphite film formation by chemical vapor deposition on Ni coated sapphire

Graphite thin films can be formed by CVD on Ni films with a thickness of 500 A deposited on sapphire (110), (001) and (012) faces. The c-axis of the graphite film deposited on Ni/sapphire (110) is almost perpendicular to the sapphire surface. However, its structure is not homogeneous nor flat. The Auger analyses for graphite/Ni/(110) indicate that there are Ni islands and the graphite film covers both the Ni islands and the bare sapphire surface. It is also found that oxygen atoms are removed from the sapphire surface during CVD and a mixing layer of Ni and Al appears. The cystallinity, orientation alignment and surface morphology of the graphite films formed on Ni/sapphire (001) and Ni/sapphire (012) are worse than those deposited on Ni/sapphire (110).

Preparation, structure, and electrical conductivity of vanadium fluoridegraphite intercalation compound

Graphite intercalation compounds (GIC) of vanadium fluoride have been prepared in a fluorine atmosphere. The GICs prepared from highly oriented pyrolytic graphite (HOPG) were stage 1–8 compounds with composition, C8.4–79.5VF5.8–6.0. The apparent size of intercalated VF6−(di) decreased from 5.33 A to 4.15 A along the c axis with increasing x in CxVF6. Various intercalated structures of VF6− between the carbon layers have been proposed for this change in di values. The compounds with small di around 4.2 A show high stability in the air, which is due to the nestling of the VF6− anion between the carbon layers. Electron diffraction measurements have indicated that a well-nestled stage 2 GIC has high regularity in orientation of intercalated VF6− anions, which make two large unit cells of the hexagonal system (a0:8.868A) with the different vectors by ±14° from that of graphite lattice. The 19F-NMR spectra and X-ray diffraction data in the low temperature region suggest a reversible phase transition. The highest electrical conductivity was 1.97 × 105Scm−1, which is 12 times that of pristine HOPG.