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?

<p>Ductility (A)</p> Signup and view all the answers

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

<p>Increases (C)</p> Signup and view all the answers

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

<p>Surface area (B)</p> Signup and view all the answers

What is a unique property of graphene?

<p>Efficient conduction of heat and electricity (D)</p> Signup and view all the answers

What is a common property of nanomaterials?

<p>Increased surface to volume ratio (D)</p> Signup and view all the answers

What is the bond angle in the structure of graphite?

<p>120o (D)</p> Signup and view all the answers

What is a use of graphite?

<p>Solid lubricants (B)</p> Signup and view all the answers

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

<p>It increases (A)</p> Signup and view all the answers

What is a characteristic of single-walled carbon nanotubes?

<p>Very low density and high strength (C)</p> Signup and view all the answers

What is the typical size range of nanotechnology?

<p>1 to 100 nanometers (A)</p> Signup and view all the answers

What is the shape of the molecule of fullerene C60?

<p>A geodesic dome (C)</p> Signup and view all the answers

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

<p>Up to 132,000,000:1 (C)</p> Signup and view all the answers

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

<p>By their structure (C)</p> Signup and view all the answers

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

<p>Van der Waals forces (C)</p> Signup and view all the answers

What is the shape of the nanostructure of nanofibers?

<p>Cylindrical (C)</p> 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.

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