| Research Abstract |
Synthesis and structural characterization of carbon nanotubes and boron nitride nanotubes are extensively performed, and studies of field emission from carbon nanotubes and its application to display devices are carried out. The following achievements are obtained.
1. Efficient production and diameter control of single-wall carbon nanotubes (SWCNTs)
Catalysts that work efficiently to produce SWCNTs by electric arc discharge are searched, and Rh-Pt, La-Ni and Ce-Ni are found efficient bimetallic catalysts. The diameters of SWNTs is found to decrease with the reduction of helium (He) pressure in the arc reactor. The average diameter varies from 1.02 nm (for 50 Torr He) to 1.5nm (for 1520 Torr He).
2. Effect of buffer gases on the growth of multiwall carbon nanotubes (MWCNTs)
Even in an atmosphere of oxygen and air, MWCNTs grow by arc discharge. MWCNTs produced in these gases contain less impurities such as graphite debris than those produced in helium gas.
3. Growth and structure characterization of boron nitride (BN) nanotubes
Nanotubes of hexagonal-BN are synthesized by arc discharge between zirconium diboride electrodes in nitrogen atmosphere. New morphology of BN nanotubes at their tips, suggesting the presence of energetically unfavorable odd-membered rings, was observed.
4. Field emission from carbon nanotubes and its application as electron sources of display devices
Field emission of electrons from a capped MWCNT exhibits field emission patterns suggesting electron emission from pentagons, and interference fringes between electron waves emanating from adjacent pentagons are also observed in the patterns. Adsorption and desorption of molecules on a nanotube tip are observed, and it is revealed that they are responsible for fluctuation in emission current. Lifetime of nanotube field emitters are investigated under various gas species. Developing these studies, nanotube-base field emission display devices are experimentally fabricated.
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