Nanotubes- Properties And Applications Final2003

NANOTUBESProperties and Applications

ByKomal Trivedi Meghna Jain

NANOTECHNOLOGY • Nanotechnology is design, fabrication and application of nanostructures or nanomaterials. It is the fundamental understanding of relationship between physical properties or phenomena and material dimensions. 1 nanometer = 3 atoms = 10-9 meters

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NANOTUBE Molecular scale tubes of graphitic carbon closed at both sides by fullerene like end caps

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Types of Nanotubes The way the graphene sheet is wrapped is represented by a pair of indices (n, m) called the chiral vector. The integers n and m denote the number of unit vectors along two directions in the honeycomb crystal lattice of graphene

• Armchair structure(m=n) • Zigzag structure(m=0) • Chiral structure 4

PROPERTIES Electrical Conductivity Their conductivity has been shown to be a function of their chirality, the degree of twist as well as their diameter. For a given (n,m) nanotube, if• n = m, metallic • n − m = (mod) 3, semiconductor (very small band gap) • else moderate semiconductor

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Strength & Elasticity Carbon nanotubes are the strongest and stiffest materials on earth, in terms of tensile strength and elastic modulus respectively. This strength results from the covalent sp² bonds formed between the individual carbon atoms. Multi-walled carbon nanotube has a tensile strength of 63 GPa). Under excessive tensile strain, the tubes will undergo plastic deformation, (deformation is permanent). This deformation begins at strains of approximately 5%

TENSILE STRENGTH

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Aspect Ratio Imparts electrical conductivity at lower loadings, compared to conventional additive materials . ( about 1000:1)

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 CNT’s is very favorable for field emission 7

APPLICATIONS Field Emission :cathode ray tube display, lightning arrestors and electron microscope sources.

CNTFET Exposed(to oxygen) –PFET Non-exposed -JFET

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Nano Composites: •Reinforced Plastics •Aircraft and spacecraft components

Fibers & Fabrics: •NASA developed jacket for Antarctic expedition •Armor •Transmission cables

Filtration: Air, Gas, Water 9

Gene therapy

Smart Bomb: implantable drug delivery systems

Bio Medical Seek & Destroy cancer cells

Artificial body parts, Prosthetics and Surgical Implants

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• Conductive adhesives and connectives • Molecular electronics -Fast computer chips, Dram memory, supercomputers • Coatings - television screen, cut glare, dust resistant coats, water repellent (construction work) • Household -self-cleaning windows, dishes, ceramics, anti-reflective sunglasses, food packaging (effect gas permeability, heat resistance). • Industrial - Cutting tools, coatings, fibers, etc

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THANK YOU 12