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Home > Introduction > Nanotubes and Buckyballs Nanotubes and BuckyballsLast Updated: Tuesday, 29-May-2012 06:53:42 PDTGo directly to Websites Nanotube:
"Conceptually, single-wall carbon nanotubes (SWCNTs) can be considered to be formed by the rolling of a single layer of graphite (called a graphene layer) into a seamless cylinder. A multiwall carbon nanotube (MWCNT) can similarly be considered to be a coaxial assembly of cylinders of SWCNTs, like a Russian doll, one within another; the separation between tubes is about equal to that between the layers in natural graphite. Hence, nanotubes are one-dimensional objects with a well-defined direction along the nanotube axis that is analogous to the in-plane directions of graphite."
A one dimensional fullerene (a convex cage of atoms with only hexagonal and/or pentagonal faces) with a cylindrical shape. Carbon nanotubes discovered in 1991 by Sumio Iijima resemble rolled up graphite, although they can not really be made that way. Depending on the direction that the tubes appear to have been rolled (quantified by the 'chiral vector'), they are known to act as conductors or semiconductors. Nanotubes are a proving to be useful as molecular components for nanotechnology. [Encyclopedia Nanotech] Strictly speaking, any tube with nanoscale dimensions, but generally used to refer to carbon nanotubes, which are sheets of graphite rolled up to make a tube. A commonly mentioned non-carbon variety is made of boron nitride, another is silicon. These noncarbon nanotubes are most often referred to as nanowires. The dimensions are variable (down to 0.4 nm in diameter) and you can also get nanotubes within nanotubes, leading to a distinction between multi-walled and single-walled nanotubes. Apart from remarkable tensile strength, nanotubes exhibit varying electrical properties (depending on the way the graphite structure spirals around the tube, and other factors, such as doping), and can be superconducting, insulating, semiconducting or conducting (metallic). [CMP] Nanotubes can be either electrically conductive or semiconductive, depending on their helicity, leading to nanoscale wires and electrical components. These one-dimensional fibers exhibit electrical conductivity as high as copper, thermal conductivity as high as diamond, strength 100 times greater than steel at one sixth the weight, and high strain to failure. NASA JSC - Carbon Nanotubes A nanotube's chiral angle--the angle between the axis of its hexagonal pattern and the axis of the tube--determines whether the tube is metallic or semiconducting. Nanotubes Under Stress A graphene sheet can be rolled more than one way, producing different types of carbon nanotubes. The three main types are armchair, zig-zag, and chiral. Examples
Copyright Professor Charles M. Lieber Group And an excellent description of Carbon Nanotube Tips for Atomic Force Microscopy Carbon nanotubes possess many unique properties which make them ideal AFM probes. Their high aspect ratio provides faithful imaging of deep trenches, while good resolution is retained due to their nanometer-scale diameter. These geometrical factors also lead to reduced tip-sample adhesion, which allows gentler imaging. Nanotubes elastically buckle rather than break when deformed, which results in highly robust probes. They are electrically conductive, which allows their use in STM and EFM (electric force microscopy), and they can be modified at their ends with specific chemical or biological groups for high resolution functional imaging. Professor Charles M. Lieber Group CNT exhibits extraordinary mechanical properties: the Young's modulus is over 1 Tera Pascal. It is stiff as diamond. The estimated tensile strength is 200 Giga Pascal. These properties are ideal for reinforced composites, nanoelectromechanical systems (NEMS). Center for Nanotechnology | Gallery Carbon Nanotube Transistors exploit the fact that nm- scale nanotubes (NT) are ready-made molecular wires and can be rendered into a conducting, semiconducting, or insulating state, which make them valuable for future nanocomputer design. ... Carbon nanotubes are quite popular now for their prospective electrical, thermal, and even selective-chemistry applications. Physics News 590, May 21, 2002 Many potential applications have been proposed for carbon nanotubes, including conductive and high-strength composites; energy storage and energy conversion devices; sensors; field emission displays and radiation sources; hydrogen storage media; and nanometer-sized semiconductor devices, probes, and interconnects. Some of these applications are now realized in products. Others are demonstrated in early to advanced devices, and one, hydrogen storage, is clouded by controversy. Nanotube cost, polydispersity in nanotube type, and limitations in processing and assembly methods are important barriers for some applications of single-walled nanotubes. Carbon Nanotubes—the Route Toward Applications Ray H. Baughman, Anvar A. Zakhidov, Walt A. de Heer AKA: Multi-wall Carbon Nanotubes (MWNTs), Single-wall Carbon Nanotubes (SWCNs), (5, 5) armchair nanotube, (9, 0) zigzag nanotube, and (10, 5) chiral nanotube. Also, single-wall carbon nanotube field-effect transistors (CNFETs). See Nanotubes, Nanocones, and Nanosheets: an applet that lets you control in 3D the components and form elements. [Steffen Weber, PhD. See his VRML gallery of Fullerenes]. Also carbon nanowalls.
Copyright Alain Rochefort Assistant Professor Engineering Physics Department, Nanostructure Group, Center for Research on Computation and its Applications (CERCA).
Bucky Ball:
AKA: Endohedral fullerenes, carbon cages.
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Nanotube, nanowhiskers, nanofibres, and buckyball links:"NASA and the Johnson Space Center (JSC) have made a commitment to pursue and drive breakthrough technologies to expand human exploration of space. The very future of space exploration depends on advanced technologies such as nanotechnology and biomimetics. Toward this goal, JSC is focusing on the development of nanotechnology based on single-wall carbon nanotubes." |
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