Synthesis, Physical Property Control and Electronic Application of Carbon Nanotubes and Nanocapsules

碳纳米管和氮化硼纳米管的合成和结构表征被广泛地进行，并且碳纳米管的场发射及其在显示器件中的应用的研究被进行。取得了如下成果：1.单壁碳纳米管（SWCNTs）的高效制备和直径控制研究了电弧放电法制备SWCNTs的催化剂，发现Rh-Pt、La-Ni和Ce-Ni是有效的单壁碳纳米管制备催化剂。随着反应器中氦气压力的降低，单壁碳纳米管的直径减小。平均直径从1.02 nm（对于50 Torr He）变化到1.5 nm（对于1520 Torr He）。缓冲气体对多壁碳纳米管生长的影响即使在氧气和空气的气氛中，多壁碳纳米管也通过电弧放电生长。在这些气体中产生的多壁碳纳米管比在氦气中产生的多壁碳纳米管含有更少的杂质，如石墨碎片。氮化硼（BN）纳米管的生长与结构表征在氮气气氛中，采用二硼化锆电极间电弧放电法合成了六方BN纳米管。发现了BN纳米管尖端的新形貌，表明存在能量上不利的奇元环.碳纳米管的场致发射及其作为显示器件电子源的应用封端碳纳米管的场致发射显示出五边形电子发射的场致发射图形，并且在图形中还观察到相邻五边形电子发射波之间的干涉条纹。观察到分子在纳米管尖端上的吸附和解吸，并揭示它们是导致发射电流波动的原因。研究了不同气体种类对纳米管场发射体寿命的影响。在此基础上，实验制作了纳米管基场发射显示器件。

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) nanotubesNanotubes 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 devicesField 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.