Carbon Nanotube Properties and Graphite Structure

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Questions and Answers

How does the number of surface atoms change with reducing particle size in nanomaterials?

Alternates

Decreases

Remains constant

Increases (correct)

What effect does the reduction in particle size have on the band gap of nanoparticles?

Remains constant

Decreases

Increases (correct)

Alternates

In nanomaterials, what happens to the melting point as the size of the particles decreases?

Decreases

Remains constant

Increases (correct)

Alternates

What aspect of a material does 'elongation to failure' measure?

Ductility Signup and view all the answers

How does the catalytic activity of catalysts change with the surface area of nanomaterials?

Increases Signup and view all the answers

What factor increases with a reduction in the size of diamond nanoparticles?

Surface area Signup and view all the answers

What is a unique property of graphene?

Efficient conduction of heat and electricity Signup and view all the answers

What is a common property of nanomaterials?

Increased surface to volume ratio Signup and view all the answers

What is the bond angle in the structure of graphite?

120o Signup and view all the answers

What is a use of graphite?

Solid lubricants Signup and view all the answers

What happens to the surface area of a material as its size decreases?

It increases Signup and view all the answers

What is a characteristic of single-walled carbon nanotubes?

Very low density and high strength Signup and view all the answers

What is the typical size range of nanotechnology?

1 to 100 nanometers Signup and view all the answers

What is the shape of the molecule of fullerene C60?

A geodesic dome Signup and view all the answers

What is the length-to-diameter ratio of carbon nanotubes?

Up to 132,000,000:1 Signup and view all the answers

How are single-walled nanotubes (SWNTs) and multi-walled nanotubes (MWNTs) categorized?

By their structure Signup and view all the answers

What is the force that holds carbon nanotubes together in 'ropes'?

Van der Waals forces Signup and view all the answers

What is the shape of the nanostructure of nanofibers?

Cylindrical Signup and view all the answers

Study Notes

Nanoparticle Properties

As particle size decreases, the percentage of atoms on its surface increases: 30nm (5%), 10nm (20%), 3nm (50%)
Increased surface area leads to increased catalytic activity of catalysts
Emission can be tuned by controlling the size of nanoparticles (e.g., CdSe nanoparticles or quantum dots)

Bandgap and Absorption Thresholds

Bandgap increases with reducing particle size (e.g., CdS nanoparticles)
Calculated bandgaps and absorption thresholds for CdS of different sizes are shown in the table

Strength and Ductility

Yield strength is the stress at which a specific amount of plastic deformation is produced
Elongation to failure is a measure of the ductility of a material
Breaking through the strength-ductility trade-off dilemma in an AlSi-based casting alloy

Carbon Nanotube (CNT) Properties

Extremely strong, stiff, and relatively ductile
Single-walled carbon nanotubes are the strongest known material
Very low densities, with the ultimate fiber being 100 times stronger than steel and six times lighter

Graphite and Graphene

Graphite: crystalline form of carbon with covalent bonding and a 120° bond angle
Graphene: a two-dimensional, atomic-scale, hexagonal lattice with unusual properties (e.g., 200 times stronger than the strongest steel, efficient heat and electricity conduction, near transparency)

Nanotechnology and Nanomaterials

Nanotechnology: science, engineering, and technology conducted at the nanoscale (1-100 nanometers)
Nanomaterials can have very different properties from bulk materials
Properties of nanomaterials include increased surface-to-volume ratio, surface effects, and increased catalytic activity
Classification of nanomaterials: nanoparticles, nanostructures, nanofibers, nanowires, nanotubes, nanothin films, and surface coatings

Fullerenes

Fullerenes: a new allotrope of carbon with a structure of a truncated icosahedron (e.g., C60 molecule, 0.7 nm in diameter)
Named Buckminster fullerene, with a soccer ball-like structure

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Description

Explore the extraordinary properties of Carbon Nanotubes (CNT), known for their strength, stiffness, and low densities. Learn about the structure of graphite, a crystalline form of carbon with various applications like solid lubricants, nuclear reactor moderator, electrodes, and pencil leads.