Preparation Of SiC Nanowires Based On Carbon Nanotubes Template

The research on one dimensional materials is the hotspot and frontier of condensed matter physics and materials science fields. As one kind of one dimensional materials,SiC nanowires have outstanding field emission capability.To date,the research on SiC nanowires is on the beginning phase,and have plenty of spaces to continue the research.The difficulty of the research work up to date is unable to synthesize SiC nanowires controllablely.The topic of this thesis is about preparation of SiC nanowires based on carbon nanotubes,including some exploring work about the controllable preparation of SiC nanowires.We bring forward our unique method to synthesize SiC nanowires, using the carbon nanotubes(CNTs) as template,then sputter the Si on them ,and by annealed at high temperature,we can get the SiC nanowires.This is a novel technique,and can synthesize SiC nanowires controllablely. The figure of SiC nanowires are affected intensely by the figure of carbon nanotubes,so we emphasize the importance of the synthesis of carbon nanotubes. We synthesized cleanly, directional carbon nanotubes successfully using acetylene and hydrogen through DC-PECVD equipment,and this method is hardly covered up to date. We also systemically studied the effects of technical parameters on carbon nanotubes.Then we sputtered the Si on them ,and by annealed at high temperature,we got the SiC nanowires. We studied the surface,structure and composition of the sample by XRD,XPS,Raman and SEM,and proved our sample was SiC indeed. At the same time,we systemically studied the effects of technical parameters on SiC nanowires.We synthesized SiC nanowires controllablely,and got SiC nanowires with all kinds of parameters.We found the directional property of SiC nanowires is superior to carbon nanotubes for the first time. The annealing temperature must beyond 1200℃and the annealing time must be longer in order to get fairly well crystalβ-SiC nanowires.And the cladding of Si must be modest,if too more ,the carbon nanotubes will be covered with Si superfluously,and we can not check up the SiC;if too little,the carbon nanotubes will be covered with Si sectionally,and we can only get partial SiC nanowires.At last ,we studied the field electron emission property of carbon nanotubes and SiC nanowires.We found that whatever carbon nanotube and SiC nanowires,the density must not be too great, otherwise the screen effect will badly damage the field emission.The length of nanowires or nanotubes can be a little longer,so we can get a lower threshold field. When the gap between electrode is 100μm,200μm and 300μm,the threshold field is 24V/μm,13V/μm and 11V/μm. It means the wider of the gap between electrode,the lower of the threshold field will be. When the gap between electrode is 200μm,the threshold field of carbon nanotubes and SiC nanowires.is 8.6V/μm and 21V/μm separately.The field emission capability of SiC nanowires is superior to carbon nanotube.