Boron-Nitride and B_xC_yN_z Nanotubes

Carbon nanotubes (or "Bucky Tubes") were discovered by Iijima in 1991. The tubes are related, in structure as well as properties, to graphite. Graphite is a planar, two-dimensional form of carbon with a very weak attraction between adjacent planes of carbon atoms. If we imagine peeling off a long segment of one graphite plane, and rolling this segment into a single tube, we get the atomic structure of a single-walled nanotube. Depending on the size of the planar segment, nanotubes could then be formed with a variety of diameters, lengths, or helicities. By wrapping additional layers concentrically, tubes with multiple walls can be imagined. Although the nanotubes are not actually synthesized in this manner, this types of variations are commonly seen in experimental samples of nanotubes. Soon after the discovery of carbon nanotubes, theorists predicted the existence of nanotubes made from other planar, or layered, materials such as BC₂N and BN. A few months after that prediction, tubes of these different stoichiometries of boron, carbon, and nitrogen were successfully synthesized in our lab and characterized by Transmission Electron Microscopy (TEM) and Electron Energy Loss Spectroscopy (EELS). The discovery of BN nanotubes, which are pedicted to be semi-conducting, has the potential of revolutionizing the electronics industry: by doping these tubes, it is conceivable to have devices on single BN tubes which have diameters on the order of nanometers and lengths on the order of microns. The BN tubes are more amenable than carbon nanotubes to these types of applications because their electrical properties are much less dependent on the specific nanotube geometry. 

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