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Nanotechnology Definition
1. Significance of Nanoscale
2. New Materials
2.1 Nanomaterials
2.2 Properties
3. Nanomaterial Science
3.1 In One Dimensions
3.2 In Two Dimensions
- Carbon Nanotubes
- Inorganic Nanotubes
- Nanowires
- Biopolymers
3.2 In Three Dimensions
- Nanoparticles
- Fullerenes (Carbon 60)
- Dendrimers
- Quantum Dots
4. Applications
4.1 Current
- Cosmetics
- Composites
- Clays
- Coatings
- Tougher Tools
4.2 Short-term
- Paints
- Remediation
- Fuel Cells
- Displays
- Batteries
- Fuel Additives
- Catalysts
4.2 Longer-term
- Nanotube Composites
- Lubricants
- Magnetic Materials
- Medical Implants
- Machinable Ceramics
- Water Purification
- Military Battle Suits
5. Carbon Nanotubes 101
5.1 History
5.2 Production Methods
- Arc Method
- Laser Method
- CVD Method
- Ball Milling
- Other Methods
5.3 Purification Methods
- Gas Phase
- Liquid Phase
- Intercalation
5.4 Dispersion
5.5 Functionalization
5.6 Properties
- Electrical Conductivity
- Strength/Elasticity
- Thermal Conductivity
- Field Emission
- High Aspect Ratio
- Highly Absorbent
5.7 Applications
- Field Emission
- Plastics
- Energy Storage
- Adhesives/Connectors
- Molecular Electronics
- Thermal Materials
- Structural Composites
- Fibers and Fabrics
- Catalyst Support
- Ceramics
- Biomedical Applications
- Air,Water,Gas Filtration
- Other Applications
6. Nanotechnology Images
 
 
Nanowerk > Introduction to Nanotechnology >
 

Introduction to Nanotechnology

 
 
d) Field Emission
Field emission results from the tunneling of electrons from a metal tip into vacuum, under application of a strong electric field. The small diameter and high aspect ratio of CNTs is very favorable for field emission. Even for moderate voltages, a strong electric field develops at the free end of supported CNTs because of their sharpness. This was observed by de Heer and co-workers at EPFL in 1995. He also immediately realized that these field emitters must be superior to conventional electron sources and might find their way into all kind of applications, most importantly flat-panel displays. It is remarkable that after only five years Samsung actually realized a very bright color display, which will be shortly commercialized using this technology. Studying the field emission properties of multi walled nanotubes, Bonard and co-workers at EPFL observed that together with electrons, light is emitted as well. This luminescence is induced by the electron field emission, since it is not detected without applied potential. This light emission occurs in the visible part of the spectrum, and can sometimes be seen with the naked eye.
e) High Aspect Ratio
CNTs represent a very small, high aspect ratio conductive additive for plastics of all types. Their high aspect ratio means that a lower loading of CNTs is needed compared to other conductive additives to achieve the same electrical conductivity. This low loading preserves more of the polymer resins’ toughness, especially at low temperatures, as well as maintaining other key performance properties of the matrix resin. CNTs have proven to be an excellent additive to impart electrical conductivity in plastics. Their high aspect ratio, about 1000:1 imparts electrical conductivity at lower loadings, compared to conventional additive materials such as carbon black, chopped carbon fiber, or stainless steel fiber.
f) Highly Absorbent
The large surface area and high absorbency of CNTs make them ideal candidates for use in air, gas, and water filtration. A lot of research is being done in replacing activated charcoal with CNTs in certain ultra high purity applications.
 
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