YOSHIMURA π-Electron Materials


This project studied the large space occupied by freely-moving π-electrons as domains of electron motion and material transformation while elucidating the unique physical, chemical, and biological phenomena which result from these domains. In order to achieve these goals, synthetic methods were developed for new materials with extended π-electron systems and showing high crystallinity.

Research Director: Dr. Susumu Yoshimura
(Senior Managing Director, Menber of the Board Matsushita Research Institute Tokyo, Inc.)
Research Term 1991~1996


Research result

Synthesis of non-benzenoid graphite:

 New synthetic methods and processes were developed for the synthesis of graphite containing 5- or 7-membered carbon rings, which form non-planar graphite with a larger interplanar spacing of 3.8-3.9 A, compared to 3.35 A of normal graphite. This fact allows a very large amount of lithium to be inserted between the planes, which could possibly be used, for instance, as a very high-capacity secondary battery.

Low-temperature graphitization:

 Using Ni as a catalyst, low-temperature graphitization of monomeric materials has been realized at 600compared to the typical 2,800, producing pure graphite. N-containing graphite was also deposited on Ni substrates.

Carbon nanotube formation:

 Carbon nanotubes have been formed at temperatures down to 600 by CVD. The morphology of the fiber depends on the source material and growth conditions. These results were shown to be useful for understanding the mechanism for the reconstruction of two-dimensional graphite into a one-dimensional-like carbon nanotube at low temperature.

Intercalation into carbon nanotubes:

 Intercalation into carbon nanotubes without breaking the tubular structure has been achieved for the first time. Both K-intercalated and FeCl3 intercalated tubes were produced. The intercalation process is accompanied with a swelling of the tube, which may be reversed by de-intercalation. The K-intercalated nanotube exhibited the universal conductance fluctuation below 5 K.

Insoluble polymer films:

 Insoluble ultrathin films of polymers have been prepared on graphite by polymerization-induced epitaxy (PIE). STM observations showed the presence of highly-ordered domains of polymers. Also, functional groups were introduced via a substitution reaction of the polymer film (post PIE).

Carbon-film deposition on various substrates:

 Conductive carbon films have been successfully deposited onto silicon utilizing chemical vapor deposition (CVD). A specially made sample of a C-Si double-layer structure was shown to have an ideal rectifying I-V characteristic; also, a “photocurrent” can be generated from the sample by irradiating it with light.

Photoluminescence from silica/carbon composites:

 A novel photoluminescence in the visible and near-infrared region was observed for silica glass dispersed with a carbon material. The result shows the possibility of using the carbon material for optical applications.


·Highly-oriented graphite thin films on a Pt/saphire substrate formed via chemical vapor deposition and their X-ray diffraction pattern


·Scanning tunneling microscope image of polydimethylsiloxane epitaxially grown on a graphite substrate

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