Resumo

HIRAKI, Akio  e  HIRAK, Hirohisa. Unique carbon-nano-structure for high quality electron-emitter to be employed in a variety of applications. Rev. mex. fis. [online]. 2008, vol.54, suppl.2, pp.44-50. ISSN 0035-001X.

There have been many trials to employ nano-carbon materials, such as carbon-nano-tubes and nano-diamond films, as electron-emitter. Several reasons exist why the nano-carbon materials are good for the emitter. They are, in addition to (a) unique morphological shapes of the materials good for the emitter- the high aspect ratio of the carbon-nano-tube is a good example-, (b) sturdiness(they can even be formed in a plasma), (c) high thermal conductivity (current density in the electron-emitting-nano-structure is high, thus it is vital to provide effective Joule-heat dissipation), and (d) easiness of the fabrication of the electron-emitting carbon materials. In order to fabricate good electron emitters, we have long been trying to employ a variety of fabrication CVD methods and fabricating conditions (starting CVD gas, pressure, temperature, substrate materials and so on).Then recently our emitters have shown a world-top-ranking property: very low turn-on- voltage(0.5V/µm induce 10µA/cm² of emission current) and high current at low applied voltage with gap distance of 1mm(1mA/cm² at 1.1V/µm and 100/ at 2V/µm). This excellent property comes from a carbon-nano-structure which we call CNX(Carbon-Nano-eXit). In addition, these emitter can be formed on a variety of substrates(Ni, Ni-Cr, SUS or others), in forms of wire or pipe, very quickly. Namely, by one reactor, it is possible to fabricate 50100 km of "wire or pipe type emitter" per month. The wire type emitter is good for both high field concentration and avoiding the so-called "edge-effect".Then using these emitters, we are able to fabricate Mercury-free fluorescence lamps with high efficiency (601m/watt) and high brightness of more than 10⁵cd/m²(white-light).

Palavras-chave : Electron emitters; CVD diamond; carbon-nanostructure; carbon nano wires.

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