Research on Precursors of Carbon Nanotubes for Control of Layer Numbers

点击翻译按钮获取中文摘要

We have succeeded to produce and purify high-quality double wall carbon nanotubes (HQDWNTs) with low diameter distribution and very few defects by a newly developed high-temperature pulsed arc discharge method. The diameter distribution of HQDWNTs is 1.6〜2.0 nm for the outer diameter, which is one of the narrowest double wall carbon nanotubes at this moment. These HQDWNTs have inter layer interaction, which does not exit in normal single-wall carbon nanotubes (SWNTs), and have novel properties coming from the layer interaction. For the atomic level structures, HQDWNTs have correlation between the inner and the outer layers. We have found that chiral helicities of the inner and the outer layers tend to have the same ones, that is, both layers have right handed or left handed structures, and that there are locally commensurate graphen stacking between the layers. The structural correlations have not been observed with other DWNTs since their structural uniformity and the graphitization of the wall are not good enough for the observations. Furthermore, transport properties of field effect transistors using HQDWNTs as channels also show the special ambipolar properties, which also come from layer interaction and structural uniformity of HQDWNTs. Now STM observation to investigate the layer interaction and details of electronic properties are in progress.As shown previously, we have succeeded to control the number of layers of SWNTs and DWNTs and to reveal the novel properties of DWNTs, which come from the layer interaction. Further researches are in progress to develop a control method for the numbers of layers by monitoring the precursors of carbon nanotubes with ion mobility method. The numbers of layers are determined very early stages of nanotubes growth in the time range of ms. The ion mobility measurements are suitable for the measurements since they are much faster than traditional methods like TEM, AFM and STM.