Preparation, Characterization And Field Electron Emission Properties Of CN_x Nanotubes

The effect of different catalysts on the quality and yield of carbon nanotubes produced by thermal decomposition of ferrocene/xylene has been studied. On the basis of this work, the CNx nanotubes with "nested-cone" shape have been produced by thermal decomposition at 780-980 with NHb released from NH4Cl as nitrogen source. We have also produced CNx nanotubes by pyrolyzing the solution of ferrocene/ethylenediamine (Fe(C5H5)2/C2H8N2) mixture at 780 -1080 . With this method, nitrogen and carbon sources are evenly mixed, and the N/C ratio can be easily controlled. A morphology transition from thinner polymerized "pearl-like" nanobells to thicker irregular "bamboo-like" compartments with increasing the temperature has been observed. EDX analysis was carried out to obtain additional information about the elemental composition. It revealed an average N content of 19at.% in the samples when C2H8N2 was selected as the nitrogen source, which was obviously higher than that when NRtCl was used ( 1%) .The effect of temperature, the ratio of Fe(C5H5)/C2H8N2 as well as the types of catalysts on the yield and structure of CNx nanotubes have been studied. The growth temperature affects greatly the yield, morphology and degree of crystallization order of the CNx nanotubes. CNx nanotube with "bamboo-like" structure grow preferentially when Fe(C5H5)2 or Fe powder are used as catalyst. It is noted that the CNx nanotubes grown on Fe(C5H5)2 catalyst have the best well-distributed "bamboo-like" structure. The catalysis growth mechanism and morphologic structure of CNx nanotube are also discussed. Raman spectroscopic studies show that the intensities of the D with respect to G band and the widths (FWHMs) of Raman bands can represent the change of the CNx nanotube's crystallinity with the nitrogen incorporation.Films of the CNx nanotube were produced by thermal decomposition on Fe-coated Si substrates, and their low field emission properties have been investigated. A high-emission current density of 1.28mA/cm2 for an applied field of 2.54V/u m was achieved, implying CNx nanotubes have better electron field emitter properties than the films of carbon tubes and BCN tubes do under same experiment conditions.