Port Structure Of Small Radius Single-walled Carbon Nanotubes And Cross-connect Analog

Carbon nanotubes (CNTs) are new carbon-related materials with nanometer diameter and perfect molecular structure. The nanotubes can be viewed as seamless hollow tubular structures being constructed from a single rolled sheet of graphite, and have very large length/diameter ratio. So they are considered as quasi-one dimensional nanomaterials. The nanotubes may consist of one up to tens and hundreds of concentric shells of carbon with adjacent shells separation of 0.34 nm. Due to their special structures with mechanical and electronic properties, nanotubes will have vast and promising prospect of application in many fields, such as nanoelectronic devices, field-effect transistors, single-electron transistors, etc.Different models have been put forward to explain the growth of CNTs. A key question concerning the growth of nanotubes is whether or not an open-ended nanotube will remain open during the growth process. The key of this article is to investigate how the open ends of CNTs change at certain temperatures. We use tight binding molecular dynamics simulations (TBMDs) to calculate and analyze the effect of temperature (1000 K—3000 K) on the end structures of perfect single-walled carbon nanotubes. The calculations indicate that the ends of nanotube are prone to be closed with the temperature increasing and almost close at 3000 K. It also suggests that we should lower the experimental temperature for the growth of open-ended nanotubes. The energy of the system descends due to the ends closing during the simulations. Moreover, since the strain energy of zigzag tubes is larger than that of the armchair tubes with the same semidiameter, the ends of the armchair tubes are easier to be closed than those of the zigzag ones. And the closed structures of the zigzag tubes have a lot of defects, even at 3000 K, there will be few carbon atoms flying away from them. At last, we investigate energetics of the structures between two crossed ultrathin single-walled carbon nanotubes (3.0 A) at some temperatures. The calculations indicate the crossed junctions can realize through formation of sp~3-related bonds and breaking of bonds in original nanotubes in (4,0)—(4,0) and (4,0)—(2,2), and the higher temperature can result in the faster junction. But two crossed (2,2) nanotubes can not link each other.