What is Carbon nanotubes: Definition and 31 Discussions

Carbon nanotubes (CNTs) are tubes made of carbon with diameters typically measured in nanometers.
Carbon nanotubes often refer to single-wall carbon nanotubes (SWCNTs) with diameters in the range of a nanometer. Single-wall carbon nanotubes are one of the allotropes of carbon, intermediate between fullerene cages and flat graphene.
Although not made this way, single-wall carbon nanotubes can be idealized as cutouts from a two-dimensional hexagonal lattice of carbon atoms rolled up along one of the Bravais lattice vectors of the hexagonal lattice to form a hollow cylinder. In this construction, periodic boundary conditions are imposed over the length of this roll-up vector to yield a helical lattice of seamlessly bonded carbon atoms on the cylinder surface.Carbon nanotubes also often refer to multi-wall carbon nanotubes (MWCNTs) consisting of nested single-wall carbon nanotubes weakly bound together by van der Waals interactions in a tree ring-like structure. If not identical, these tubes are very similar to Oberlin, Endo, and Koyama's long straight and parallel carbon layers cylindrically arranged around a hollow tube. Multi-wall carbon nanotubes are also sometimes used to refer to double- and triple-wall carbon nanotubes.
Carbon nanotubes can also refer to tubes with an undetermined carbon-wall structure and diameters less than 100 nanometers. Such tubes were discovered in 1952 by Radushkevich and Lukyanovich.While nanotubes of other compositions exist, most research has been focused on the carbon ones. Therefore, the "carbon" qualifier is often left implicit in the acronyms, and the names are abbreviated NT, SWNT, and MWNT.
The length of a carbon nanotube produced by common production methods is often not reported, but is typically much larger than its diameter. Thus, for many purposes, end effects are neglected and the length of carbon nanotubes is assumed infinite.
Carbon nanotubes can exhibit remarkable electrical conductivity, while others are semiconductors. They also have exceptional tensile strength and thermal conductivity because of their nanostructure and strength of the bonds between carbon atoms. In addition, they can be chemically modified. These properties are expected to be valuable in many areas of technology, such as electronics, optics, composite materials (replacing or complementing carbon fibers), nanotechnology, and other applications of materials science.
Rolling up a hexagonal lattice along different directions to form different infinitely long single-wall carbon nanotubes shows that all of these tubes not only have helical but also translational symmetry along the tube axis and many also have nontrivial rotational symmetry about this axis. In addition, most are chiral, meaning the tube and its mirror image cannot be superimposed. This construction also allows single-wall carbon nanotubes to be labeled by a pair of integers.A special group of achiral single-wall carbon nanotubes are metallic, but all the rest are either small or moderate band gap semiconductors. These electrical properties, however, do not depend on whether the hexagonal lattice is rolled from its back to front or from its front to back and hence are the same for the tube and its mirror image.

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  1. J

    Standard enthelpies of formation of carbon nanotubes etc.

    I am curious about the standard enthalpies of formation of carbon nanotubes, diamond, carbon buckyballs, graphene, etc. I read from physics forums that the standard enthalpies of formation of these allotropes of carbon are small. However, since diamond is fabricated naturally under extreme...
  2. D

    Elasticity (Yield Strength) of Carbon Nanotubes

    I'm trying to find the Yield strength, that is how much force can be applied to carbon nanotubes so that they stretch to the limit before plastic deformation. And also how much they stretch at this limit. Do they stretch at all? Or are they always the same length until the Ultimate Tensile...
  3. N

    Carbon nanotubes from human-crafted nanopores?

    Would it be feasible to synthesize carbon nanotubes from a carbon gas source that had passed through a man crafted nanopores (nanoholes, nanochannels), the outflowing end of which is covered with a catalyst? This artificial membrane would separate gas source chamber from a product chamber...
  4. alantheastronomer

    Can carbon nanotubes be used in computer chips?

    Are carbon nanotubes a viable substitute for wires in computer chips, which might be a solution for the heating problem?
  5. Nod

    A Charge density of carbon nanotubes and graphene

    Hi everyone! I'm trying to solve the following problem: given the charge densities of carbon nanotubes and graphene, the charge density difference of 2 systems must be found. So I need to unfold in some way the nanotube and compare it charge density with the graphene's one. But how this...
  6. G

    I Circular electron propagation in carbon nanotubes?

    Can carbon nanotubes support electron propagation perpendicular to the axis? That is, can there be circular current flow on the tube's perimeter, not just the linear flow parallel to the axis? Because I reading that it's generally considered a 1-dimensional conductor.
  7. H

    Van der Waals forces between woven carbon nanotubes

    I was watching the following TED Talks video about using carbon nanotubes to build a space elevator: After the 12-13 minute point the speaker starts describing how very short carbon nanotubes can be pulled from a "nanotube forest" and spun together to create a very long thread. However the...
  8. H

    What is the advantage of CNT and graphine capacitors

    i'm fairly new to the world of electricity an was just wondering why capacitors with graphine and carbon nanotubes are better than conventional. is it just due to increased surface area?
  9. L

    Miscellaneous wonders: The Carbon Nanotube Earth Veil

    Okay so to start, this is just about the most random inapplicable proposal ever, so bear with me. Its just a cool question to consider. So, here goes: What would happen, (again, this is highly theoretical) in the instance that an enormous screen - much like the ones that rests behind most...
  10. AdrienJ

    [Video] Carbon nanotubes & single photons

    Hi, I'm currently doing a PhD about how to use carbon nanotubes as an efficient single photon source. On my spare time I've done a short video to explain it to my familly and friends. I thought you might be interested, so here it is :
  11. M

    What is the relationship between Fermi Energy and carbon nanotubes?

    What would be a good Internet link that would properly explain Fermi Energy or (Fermi Level)? How does the Fermi Energy of a material vary with external influence, such as doping of the material, and applied electric and magnetic fields for instance? What other factors can effect Fermi Energy...
  12. L

    Where would you buy carbon nanotubes?

    Wouldn't have to be long ones. Cheap and cheerful amounts. A google search brought up one called cheaptubes.com, anyone had experience with them?
  13. A

    Solving Carbon Nanotube Model with Lz & Ly Expectation Values

    Im doing a problem with a simple model of a carbon nanotube. In this we have an electron which is bound to the surface of a cylinder from which there is a radially outpointing electric field. We choose to put the x-axis along the axis of the cylinder such that the coordinate describing rotation...
  14. J

    Mass on a leash and carbon nanotubes

    Hello, I've been trying to describe small oscillations of a mass (1000kg) on a leash - like a space elevator, just without the actual elevator. I have no difficulties calulating the oscillations, but what confuses me is realization of such device. I've been looking into properties of caron...
  15. H

    Scattering by Multiwalled Carbon Nanotubes

    I am interested in the use of carbon nanotubes for making transparent conductive films, for example to replace indium tin oxide. When I looked up papers on the subject, I noticed that most of the work to date has used single-walled carbon nanotubes. Initially I was under the impression that...
  16. H

    Quantised Conductance - Doped Carbon Nanotubes

    As I understand it, carbon nanotube (CNT) exhibits quantised conductance (2e^2/h) because the mean free path length of carbon nanotubes are often longer than the length of the tubes. If one is to substitutionally dope CNTs (say armchair metallic CNTs) with other atoms of similar size, for...
  17. T

    Can zigzag carbon nanotubes be expressed as a mathematical vector?

    Homework Statement I'm trying to express the conditions for a zigzag carbon nanotube in a mathematical vector. Homework Equations B = na1 + ma2 The Attempt at a Solution I want to say "either a=0 or b=0", but must I also say that it can't be a=b=0 or is that already excluded in...
  18. J

    Carbon Nanotubes (CNT) Safeguards Info Needed

    We would be working on with Carbon Nanotubes (CNT) for post graduate research. We are doing a thesis on liquid crystals and would be using CNT. Please let us know what what safeguards and precautions have to be taken when working with it in our lab. Search engines have shown sites that say...
  19. T

    Can multi-walled carbon nanotubes (MWCNT) slide telescopically?

    Greetings, I'm trying to find out whether or not straight multi-walled carbon nanotubes (MWCNT) have the ability to slide telescopically. Although I have no formal education on the subject, my suspicion is that quantum interactions will inhibit axial motion, but I'm intrigued as graphite...
  20. K

    Calculating Volume of Carbon Nanotubes in Aligned Arrays

    Consider the following hypothetical situation. A solution of pure single walled carbon nanotubes is attached to a base (flat surface) with a regular array of "chemical hooks" which bind to a functional end of the nanotube. The tubes are connected to a similar base at the other end and then...
  21. E

    Questions about Carbon Nanotubes

    Anyone know a good source to learn more about them. Recently I was watching a video at www.ted.com and a speaker purposed interesting concepts about single layer carbon nanotubes. Questions I have: Acceleration of particles(The speaker said something about accelerating particles using...
  22. E

    Carbon nanotubes used by 17th century Damascus

    http://www.rsc.org/chemistryworld/News/2006/November/15110602.asp Carbon nanotubes are no longer the proud boast of 21st century materials scientists. It appears their discovery was unwittingly pre-empted by mediaeval Muslim sword-smiths whose tough Damascus blades taught the Crusaders the...
  23. S

    Carbon Nanotubes: Current Research & Sources

    [SOLVED] Carbon Nanotubes I'm doing some work with carbon nanotubes, their history, their uses, technology that incorporate them, and generally looking into the field. Can anyone tell me any reputable sources for information regarding current research in carbon nanotubes? Are there any...
  24. R

    Ultra high magnetic fields using carbon nanotubes

    As described in this report, the limits on the strength of stable magnetic fields are due to the magnetic forces on the conducting elements that tend to tear them apart: Magnetic Radiation Shielding: An Idea Whose Time Has Returned? Geoffrey A. Landis "The limit to the mass required to...
  25. K

    Thermal stability and electric conductibility of carbon nanotubes

    I'm trying to gather properties of carbon nanotubes and compare them to other materials, but I can't find anything about its thermal stability and electric conductibility. Any suggestions where to search?
  26. Astronuc

    Damascus steel and carbon nanotubes

    from UPI Materials: Carbon nanotubes in an ancient Damascus sabre Nature 444, 286 (16 November 2006) | doi:10.1038/444286a; Received 24 July 2006; Accepted 25 October 2006; Published online 15 November 2006 http://www.nature.com/nature/journal/v444/n7117/abs/444286a.html M. Reibold1,2...
  27. W

    Using Carbon Nanotubes for Electron Guns

    Hi All, I was reading about carbon nanotubes on wikipedia and they seem to be a pretty interesting development. Wikipedia indicates that they are using in producting better electron guns, and I was wondering if anyone knew how they are being used to do so. My unserstanding of current...
  28. C

    Could interlocking carbon nanotubes revolutionize material strength?

    (I'm not a material engineer so I apologize if any part of this post is idiotic.) The main problem with carbon nanotubes is the difficulty with growing them long enough to be of any use. After doing some research, I found a site about carbon nanotube rings. So it got me thinking, why not...
  29. S

    Basic Mechanical Properties of Carbon Nanotubes

    I'm looking for information on the maximum possible strength of SWNTs. What effect do thermodynamically inevitable(over macro scale lengths) lattice faults have on the tensile and compressive strength of the tubes? What effect does tube chirality and diameter have on tensile and compressive...
  30. A

    Help finding some papers on carbon nanotubes

    Let me explain my situation. Recently I was admitted to a material science laboratory at my university (University of Puerto Rico). We are going to try to grow carbon nanotubes by the Chemical Vapor Deposition (CVD) process. My first step is to get information on the technique (wich is...
  31. B

    Questions about Carbon Nanotubes

    I don't know if this is in the right forum but it seemed to fit quite nicely in here :P I was wondering about cxarbon nanotubes. There said to be really very strong, but what i don't underdtand is why? There so very thin! Doesd nanotechnology behave differasntly to microtechnology due to the...