Carbon Nanotubes 

Types of Nanotubes    Manufacture of Carbon Nanotubes   Uses for Carbon Nanotubes   Nanotube Companies

 

The Next Fifty Years: Science in the First Half of the Twenty-first Century

 

 
The formal name for Carbon Nanotubes is truncated icosahedron also known as "buckytubes", very basically, they are molecules made from carbon atoms.

They are unique for their size, shape, and  physical properties. They are 20 times as strong as steel, able to bend without breaking, and conduct electricity 1,000 times better than copper. Physical Properties of Carbon Nanotubes   Nanotubes are generally only a few nano-meters in diameter {a nanometer spans only three or four atoms}, and may be may be as long as a few millimeters. The length-to-width aspect ratio is extremely high. 

Interest from the research community first focused on Carbon Nanotubes exotic electronic properties, since nanotubes can be considered as prototypes for a one-dimensional quantum wire.  As other useful properties have been discovered, particularly strength, interest has grown in a multitude of other potential applications. "Carbon nanotubes could be used, for example, in nanometer-sized electronics or to strengthen polymer materials. " Mildred Dresselhaus  ...Physics Web Jan. 1998
Types of Carbon Nanotubes

Single-walled (SWNT)

a diameter of close to 1 nanometer, with a tube length that can be many thousands of times longer. Single-walled nanotubes with length up to orders of centimeters have been produced . SWNTs exhibit electric properties not shared by their multi-walled counterparts. Single-walled nanotubes are the most likely candidate for the miniaturization of electronics past the current micro electromechanical level.


Multi-walled (MWNT)

Multi-walled nanotubes consist of multiple layers of graphite rolled in on themselves to form a tube shape.

Among MWNTs are double-walled Carbon Nanotubes (DWNT) which have a more effective resistance to chemicals. This is  important when specific functionalization is required - means grafting of chemical functions at the surface of the nanotubes) to add new properties to the CNT.


Fullerite
Fullerites are a form of fullerene. They are comparable to diamond in terms of hardness. However, due to the way that nanotubes intertwine, they lack the corresponding crystal lattice that makes it possible to neatly cut diamonds . This same structure results in a less brittle material, as any impact that the structure sustains is spread out throughout the material. Another form Ultrahard fullerite has been found to be harder than diamond, and which can be used to create even harder materials, such as aggregated diamond nanorods, which could have a multitude of Industrial applications.

Diamonds are not forever -Physicists in Germany have created a material that is harder than diamond. -Physicsweb.org


 

Nanotori
Nanotori or nanotorus, are carbon nanotubes bent into rings. Nanotori have some unique properties, in particular magnetic moments 1000 times larger than previously expected for certain specific radii. Properties such as magnetic moment, thermal stability, etc. vary widely depending upon radius. Nanotori could provide very sensitive magnetic detectors.

"Nanotorus" nets giant magnetic moment Physicsweb.org

 



Nanoknot
Carbon nanotubes are being used to make nanoropes; nanoknots (or nano-knot) have been tied. Science published micrograph images of some nanoknots tied from using threads made of single-wall carbon nanotube(SWNT). (Scientific American: Tying Nano-knots)

It is anticipated that nano-knotting will reveal material characteristics that will not be found in unknotted nanothreads. Nano-lashings might use nanoknots to terminate as nano-items are bound together by nanomachines to construct more complex nano-items.

 

Carbon Nanohorns are Single-walled carbon cones with properties very similar to nanotubes . They were produced by high temperature heat treatments of fullerene soot . Carbon nanohorns have the same graphitic carbon atom structure as normal carbon nanotubes, however when many of the nanohorns group together an aggregate (a secondary particle) of about 100 nanometers is created. The advantage being, that when used as an electrode for a fuel cell, not only is the surface area extremely large, but also, it is easy for the gas and liquid to permeate to the inside. In addition, compared with normal nanotubes, because the nanohorns are easily prepared with high purity. It is expected to become a low-cost raw material.

Buckyballs are a form of carbon60  that has a unique molecular structure which can best be associated with a soccer ball. The structure has 32 faces, 12 are pentagons and 20 are hexagons. It has a  hybridized carbon atom located at all 60 of the vertices of the molecule.  Carbon 60 is not the only form of buckyball. They can form into clusters exceeding 100 carbon atoms. However, when more atoms are added to the buckyball, it loses its perfect symetry, and becomes egg-shaped. The symetry of carbon 60 makes it the most stable form of Buckyball. Buckyball is a form of pure carbon along with graphite and diamond .

Interatomic bonds within a molecule are strong (like a diamond), while the bonding between molecules when it is in the solid crystal phase is weak (like the interlayer bonding in graphite) thus giving the structure the ability to hold a molecule of a different substance inside of itself without affecting either molecules properties.  Buckyballs are a material that hold tremendous promise for the future .

 

  
Uses for Carbon Nanotubes  

 

  1. Uses of Nanotubes in Fuel Cell Technology

  2. Uses of Nanotubes in Solar Cells

  3. Uses of Nanotubes in Space Exploration

  4. New composite materials from Nanotubes

  5. Uses of Nanotubes in Electronics

  6. Uses of Nanotubes in Computers

 

 

 Applications of Nanotubes in Fuel Cell Technology  

  1. As a Hydrogen Storage Medium
  2. As a Hydrogen Sensor

Hydrogen Storage Medium

Carbon NanoTubes have been suggested for use in Fuel Cell applications as a hydrogen storage medium [See also Fuel Cells ].  Carbon nanotubes/ Fullerenes, have been viewed as a potential hydrogen storage medium for some time. They are similar in structure to a roll of graphite or the spherical "buckyballs".

A primary hurdle in utilizing nanotubes’ as a hydrogen storage medium is the ratio of stored hydrogen to carbon. As per the US Department of Energy, a carbon material needs to store 6.5% of its own weight in hydrogen to make them useful for vehicular fuel cell applications.

MIT researchers claim to have produced nanotube clusters able to store 4.2% of their own weight in hydrogen.

The University of Singapore released figures for nanotubes fibers they claim can store 10-20% of their weight in hydrogen.

Researchers have proven that "carbon nanotubes "decorated" with titanium or other transition metals can latch on to hydrogen molecules in numbers more than adequate for efficient hydrogen storage, a capability key to long-term efforts to develop fuel cells...."  'Metal-Decorated' Nanotubes Hold Promise for Fuel Cells

Researchers at SSRL and Stanford have added hydrogen to Carbon nanotubes. Recent experiments at SSRL and the Advanced Light Source in Berkeley have shown that the tubes are also a promising material for storing hydrogen safely, efficiently and compactly.  physorg.com
 

 

 

Hydrogen Sensor

Hydrogen sensors would not only be useful in Fuel cells, currently they are used in industrial quality control in food plants . In combustion systems of conventional gas-burning automobiles to monitor pollution ,as diagnostic tools to monitor certain types of bacterial infections in infants.

Resaerchers are developing methods of utilizing nanotubes for a highly improved Hydrogen sensor. "Titania nanotubes are 1500 times better than the next best material for sensing hydrogen"

Nanotubes Potential  Use in Solar Cells   

Titania Nanotubes Promise Better Solar Cells. : An article from: Nanoparticle News


Researchers from Britain's Cambridge University engineering department have developed photovoltaic devices that, when doped with single-wall carbon nanotubes , perform better than undoped devices. Nanotube diodes were made by depositing organic films containing single wall nanotubes on glass substrates coated with indium-tin oxide . Aluminium electrodes were then thermally evaporated under a vacuum to form a composite sandwich. The interaction of the carbon nanotubes with the polymer poly-3-octylthiophene (P3OT) allows excitons generated by light in the polymer to dissociate into their separate charges and travel more easily.   "The electrons travel through the nanotube length and then hop or tunnel to the next nanotube." [1] This results in an increase in the electron mobility and balances the charge carrier transport to the electrodes. In addition, the composite's conductivity is increased by a factor of 10, indicating percolation paths within the material.  -Carbon nanotubes to improve solar cells  EETimes


High performance semiconductor nanocrystals active throughout the visible spectrum and into the near-infrared have been combined with conductive polymers to create ultra high performance solar cells that exceed the capabilities of current technology. Because the nanocrystals harvest a greater portion of the energy spectrum, these plastic solar cells have significantly improved efficiencies. Quantum dots for solar roofing tiles that are based on metal nanoparticles are expected to be commercialized within the next several years.  -Strem Chemicals


 

 

New composite materials from Nanotubes

with increased conductivity/ strength to weight ratios  

Ways to blend nanotubes with plastics and ceramics are being explored, to produce new composites with unprecedented strength-to-weight ratios and high conductivity.

Uses of Nanotubes in Electronics   

Carbon Nanotube Electronics by Ali Javey and Jing Kong
 

"Nanotubes can conduct electricity much faster than metals — you get 'ballistic' transport of electrons, so if you connect transistors with nanotubes you can increase both the speed and the density of devices by several orders of magnitude. Our ability to grow nanotubes in any orientation will facilitate [building] those kinds of devices " Pulickel Ajayan  Rensselaer Polytechnic Institute.

Carbon nano-wires

Nanowires are still experimental . Experiments have demonstrated tat they can be used to build a new generation of computers.  It's very possible that semiconductor nanowire crossings will be important to the future of digital computing.


Nanowires are being studied for use as photon ballistic waveguides as interconnects in quantum dot/quantum effect well photon logic arrays. Photons travel inside the tube, electrons travel on the outside shell. When two nanowires acting as photon waveguides cross each other the juncture acts as a quantum dot. Because of their high aspect ratio, nanowires are also uniquely suited to dielectrophoretic manipulation

Potential uses as electronic and opto-electronic nanodevices, for metallic interconnects of quantum devices and nano devices, and to explore the limits of magnetic storage are other hypothetical applications . Nanowires are likely to have many other uses as nanotechnology advances.

Carbon nano-wires encased in insulating boron nitride nanotubes have been created by W. Mickelson and colleagues. Such technology could contribute to the continued shrinking of electrical devices and provide an alternate route to making insulated nanowires. "  - Global technoscan.com

Researchers from Japans Meijo University have discovered a method to make carbon nanowires that measure only a few carbon atoms across. The researchers formed carbon nanotubes by shooting a plasma arc between a pair of carbon electrodes in a hydrogen atmosphere. The hydrogen atoms kept the chemical bonds at the growing ends of the nanotubes open, and smaller carbon nanotubes grew inside larger ones; when the hollow core of a nanotube became too small to fit a tube, a single chain of atoms filled the core to form a nanowire. "We discovered that very long 1D linear carbon chains consisting of more than 100 carbon atoms could be inserted into multiwalled carbon nanotubes to form a new 1D carbon allotrope - carbon nanowires," Yoshinori Ando of Meijo University These researchers are currently exploring the mass-production of carbon nanowires, and are trying to insert carbon chains into single-walled carbon nanotubes.

Now, Forests of Nanowire Trees.: An article from: Electronic Materials Update

Droplet studies lead unexpectedly to nanowires.(Processing And Characterization): An article from: Nanoparticle News

Nanotube transistors

Nanotube transistors -Amazon

Forked nanotubes - Another area of interest is "forked nanotubes" research has shown that Y shaped nanotubes amplify current, a necessary property for transistors. These nanotubes also allow current to flow in only one direction, meaning they could be used to convert alternating current to direct current.  Transistors- the basic building blocks of most modern electronic devices including computers, have three points of contact. The forked nanotubes naturally have three terminals or points of contact.

Nanotube Transistor Improved With Polymer.: An article from: Nanoparticle News

Nanotube transistors outperform silicon. (Carbon Nanostructures). [IBM conducts research]

Uses of Nanotubes in Computers

Nanotechnology Applications to Telecommunications and Networking

One of several revolutionary methods of building futuristic computers involves carbon nanotubes .
At Harvard University, A small jolt of electric current bends the top of one nanotube down to meet another
and a nano-switch is formed --a switch somewhere in the neighborhood of 100 times smaller than those in
current state of the art computers. {The smallest features possible with today's photolithography are about 125 nanometers wide.}  In principle-Arrays of these switches could be connected to form
a logic circuit that would enable a computer to operate incredibly faster and more efficiently-combining ultra fast computing power with extremely low electrical requirements. Basically all the information on your current hard drive , AND the computer itself could be compressed into a Dick Tracy style wrist watch. A billion bits of data storage on a chip slightly larger than a freckle .

One Company -Nantero- hopes to start selling computer memory chips built with carbon nanotubes

They are developing a product they call NRAM™, a high-density nonvolatile random access memory chip, using nanotubes. The company's objective is to deliver a product that will replace all existing forms of memory, such as DRAM, SRAM and flash memory, with NRAMTM serving as the universal memory. If they are successful Nantero could be what IBM was to the 70s & 80s and what Microsoft has been to the 90s and current decade.

 

Another company Applied Nanotech, Inc {Not to be confused with Applied Nanotechnologies, another nanotech upstart} Applied Nanotech, Inc is a subsidiary of Nano-Proprietary  is producing new carbon nanotube composites with significantly improved properties for electron field emission applications. Their process replaces the electron generating element- cathode, at the rear of any CRT screen. This solves multiple problems that haunt current CRT technology, primarily the heat generated and power consumed.  By using nanotubes Applied Nanotech, Inc also eliminates the typical long neck of the today's CRT picture tubes. The nanotube composites would further reduce the voltage necessary as well as the cost of materials .

 

Uses of Nanotubes in Space Exploration

Carbon Nanotubes Military Appliactions    

 


 
Manufacture of Carbon Nanotubes  

 

MIT COMBUSTION TECHNOLOGY

 

 CVD GROWTH PROCESS OTHER PROCESSES
MIT Combustion Technology 

One relatively new process  Nano-C LLC.  combustion technology may make mass production of fullerenes a reality.

A new mass production process from Nano-C LLC. The company says it is currently scaling up a patented combustion synthesis process that will vastly reduce the cost of fullerenes  [ See Press Release of 11/26/2001]

 "The new combustion process will drop the price of fullerenes from today's 
$15 to $20 a gram to as little as 20 cents a gram," says Jack Howard, a 
professor of Chemical Engineering at MIT, who is Nano-C's Chairman and 
Founder. 

This advance will finally allow industry to obtain the volume  of 
fullerenes needed for commercial production.

"We think our process can help increase fullerene 
production to tons a month by 2004 to supply a market that is estimated to 
exceed $100 million annually by then." 

The process employed by Nano-C is  based on proprietary combustion technology exclusively licensed from MIT  [ http://web.mit.edu/anish/www/MITcomb.html ]

THE PROCESS
"The process involves the combustion of hydrocarbon fuel under sub- atmospheric pressure in a chamber or combustor in which the flame is stabilized on a porous water-cooled metal plate referred to as the burner. 
The fuel is premixed with oxygen and an inert gas and is then fed through the burner. The flame is operated with an excess of fuel such that some unburned carbon-containing molecules and soot particles remain in the hot combustion 
products after all the oxygen has been depleted. Combustion conditions, such as pressure, temperature, fuel/oxygen ratio and inert gas/oxygen ratio, can be adjusted to preferred values such that fullerenes C60 and C70 are formed in 
substantial quantities and in the desired ratios. "


Nano-C has signed its first non-exclusive licensing agreement with 
Fullerene International Corporation (FIC), a Mitsubishi Corporation joint 
venture. 
 

 

CVD Growth Process of Carbon NanoTubes

Nano Lab Inc. of Brighton, Massachusetts produces nanotubes using the "CVD growth process, a A chemical-vapor deposition technique developed at Rensselaer Polytechnic Institute. (Advanced technology 4/16/2002)

CVD process tames carbon nanotube growth

NON TECHNICAL SUMMARY OF " The CVD Growth Process "

 "Catalyzed chemical vapor deposition is the most practical method for development of carbon nanotube devices. It is both scalable and compatible with integrated circuit and MEMS manufacturing processes. CVD allows high specificity of single wall or multi wall nanotubes through appropriate selection of process gasses. Carbon feedstock comes from the decomposition of a feed gas such as Methane or Ethylene. The high stability of the feed gas prevents it from decomposing in the elevated temperatures of the furnace, typically 700 to 1000 degrees Celsius. Decomposition of the feed gas occurs only at the catalyst sites, reducing amorphous carbon generated in the process. Decomposed carbon molecules then assemble into nanotubes at the catalyst nano-particle sites.

Catalyst nano-particles can be patterned on a substrate lithographically to seed nanotube growth at intended locations. The growth of nanotubes can be caused to originate at a site of electrical connection or of mechanical significance.  "... Nano  Devices Inc

 

Other Processes & Notes 

  1. Toshiba is using carbide materials with fluorine or chlorine at raised temperature

  2. NEC has demonstrated the ability to make them using laser light on carbon materials.  

  3. Sony has used platinum and (buckyballs) 

  4. Shimadzu Corp. has described a method of low temperature mass production.

  5. Mitsubishi Chemical Corp.  has developed technology they claim could reduce the cost of making a carbon nanotube by some 99% to under Y10,000 per kilogram.  

  6. "Mitsubishi Corporation makes and proposes business plans for commercialization of Fullerene/Nanotube products in Asia including Japan, by providing solutions in research & development, marketing and investment." http://www.mcfullerene.com/partner/e_index.html

  

Nanotube  Companies

 

For related Nanotech ventures See: Nanotech Companies

  • Atomate: CVD reactors for nanotube and nanowire synthesis synthesis
  • ANU: Carbon and Boron Nitride nanotubes
  • Bucky USA  Supplier of Fullerenes -NanoTubes & related matter.
  • Carbon Nanotech. Inc. Supplier of Bucky Tubes/ Nano Tubes
  • Carbon Solutions  chemistry, applications and commercialization of single-walled carbon nanotubes
  • C-60  The company's drug development focus is on the unprecedented antioxidant activity of fullerenes. C Sixty and its strategic partners believe that fullerene antioxidants are likely to have significant impact on several unsolved diseases including Parkinson's, Alzheimer's, stroke and atherosclerosis, as well as more common skin conditions related to aging and exposure
    to sun.
  • Carbolex  Manufacturers of single-walled carbon nanotubes
  • Eikos  Carbon Nanotube Formulations for Coatings.
  • First Nano Catalyzed CVD Carbon Nanotube Growth. Spun-off from NanoDevices
  • Fullerene Int'l.  A Joint Venture of Materials and Electrochemical Research Corp., Research Corporation Technologies, Mitsubishi Corporation .in a joint venture to commercialize fullerene materials
  • Guangzhou: Single- and Multiwall Carbon Nanotubes
  • Hyperion Catalysis International  Carbon nanotube development and commercialization. Nanotube composites used in Automotive Fuel Systems and electronic environments.
  • Iljin NanoTech. Supplier of Doubled Wall Carbon Nano Tubes
  • International Carbon Inc.  Startup high-technology business dedicated to the production of Carbon nano-structures
  • MER Corp.  Advanced composites, powders, coatings and fullerenes as well as energy conversion systems
  • NanoCarb Lab. Russian Producer of Carbon Nano Tubes
  • NanoLedge  Designs and develops  multi-functional materials and fibers out of carbon nanotubes., Nanotubes production. Manipulation of nanotubes, adapting them to composite polymers and integrating them into its exclusive nanotubes macrofiber for custom applications.
  • Nanomix  Produces sensors operating between molecular and macroscopic levels. Electrical properties of carbon nanotubes are monitored macroscopically as they respond to chemical changes. They have demonstrated extremely high sensitivity, over a broad range of analytes in gas and liquid environments sensors that can be tuned to respond selectively to a variety of chemicals. Biosensors, Chemical, and Light sensors. "Converting Molecular presence & Light into an electronic signal"
  • Nano Structures & Amorphous Materials Inc. a wide variety of nanoscale powders and amorphous alloys. metals, graphite, diamonds, multi-walled and single-walled carbon nanotubes.
  • NEC Corporation  NasdaqNM:NIPNY  Multinational Conglomerate delving into Fabrication of Carbon Nanotubes and related fullerenes
  • Rosseter Holdings  Carbon Nanotube and related materials production . Research and Development Activities focused on methods and innovative processes of production for use in specialized applications
  • SEOCAL: CVD reactors for nanotube and diamond film synthesis
  • SES Research  Carbon nanotube & related fullerene production. Manufactured one of the first fullerene production machines.
  • Sun NanoTech  Multiwall carbon nanotubes.
  • Versilant Nanotechnologies  Nano-materials fabrication./ Produces useful products out of carbon nanotubes for a variety of sectors . Does not produce nano tubes or fullerenes.
  • Xidex Corporation Carbon nanotube tips for the semiconductor industry, biology, materials science and other scanning probe applications.
     
Nanotech Fortunes should be considered a "must read" for anyone interested in nanotechnology. General readers seeking to ascertain the staggering potential of nanotechnology will find this work useful, as will those who want to know how, when, and in what ways nanotechnology will affect large and small businesses. For those considering investing in nanotechnology, now or in the future, "Nanotechnology Fortunes" is simply invaluable. "

Nanotechnology For Dummies This title demystifies the topic for investors, business executives, and anyone interested in how molecule-sized machines and processes can transform our lives. Along with dispelling common myths, it covers nanotechnology's origins, how it will affect various industries, and the limitations it can overcome

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1 Emmanouil Kymakis, co-author of the papers in Applied Physics Letters