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GRAPHITEDIAMONDBonding: 3 sp2 and 1 piBonding: Four sp3 bonding

crystallizes in the hexagonal system.

crystallizes in the cubic system.

opaque.highly transparent.conductor of electricity.excellent electrical insulator.

very good lubricant.ultimate abrasive.

one of the softest materials known.

Synthetic nanocrystalline diamond is the hardest material known.

Surface of a Graphite Crystal

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High Resolution TEM image of Graphite

Graphite Flake

Three-dimensional Schematic of the Graphite Structure

Edge States of a Graphene Sheet

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Variation of Graphite StructureLecture 3: Fullerenes

Reference:

Nanomaterials Handbook, Edited by Y. Gogotsi, Taylor and Francis, Boca Raton, FL, 2006

Chapter: Fullerenes and their derivatives

From “Nanotech. for dummies”

Schematic of Smalley Apparatus for Generating Carbon-cluster Beams

http://www.chemistry.wustl.edu/~edudev/Fullerene/discovery.html

1985 - Discovery of the fullerenes by Kroto, Curl, Smalley and co-workers.- H.W. Kroto, J.R. Heath, S.C. O’Brien, R.F. Curl, R.E. Smalley, Nature 318 (1985) 167

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a) Low helium density over graphite target at time of laser vaporization. b) High helium density over graphite target at time of laser vaporization.c) Same as b), but with addition of "integration cup" to increase time between vaporization and cluster analysis.

No. of carbon atoms per cluster

Kroto and Smalley’s Experimental Results

Distribution of carbon clusters produced under various experimental conditions.

Carbon Allotropes

Comparison of Size

Fort Worth –Casa MagnanaR. Buckminster Fuller

The molecule was named for Richard Buckminster Fuller, a noted architect who popularized the geodesic dome.

Origin of the Name of Fullerenes

http://en.wikipedia.org/wiki/Fullerene

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R.F. Curl, R.E. Smalley, Fullerenes, Sci. Am., 1991, October issue

Structure of FullerenesA closed 3D carbon structure containing only pentagons and hexagons can form the following structures:•C20: the smallest possible fullerene, containing twelve pentagons and zero hexagons. However, such a structure would possess a great deal of strain, because the local topology at each carbon center would be highly non-planar. •C28, C32, C50. Because the molecular strain tends to be concentrated in the five-member rings that are responsible for closure, structures that avoid contiguous (edge-sharing) pentagons are particularly stable.•C60 and C70 are the smallest carbon clusters avoiding contiguous pentagons.

C32 C70 C78

Stone-Wales Transformation in Fullerenes

Interconversion between fullerene isomers can be achieved by rotation of atom pairs in the molecules about their mutual bond center (Stone-Wales transformation). The activation energy for this process in C60 is very high - about 6.2 eV.

http://newton.ex.ac.uk/research/qsystems/people/latham/papers/1995/C/C.abs.html

Clearly, the proposed structure for C60 is not planar! The angle between the p axis and the C-C bond vector is 101.6° (as compared to 90° in planar graphite). The bowl-shape or concavity at each sp carbon center introduces some strain into the molecule. However, the high symmetry distributes that strain evenly across the entire structure.

Atomic Bonding

Haddon, R.C., Chem. Res., 1992

Physical Properties of C60• Density: 1.65 g cm-3

• Standard heat of formation: 9.08 kcal/mol• Index of refraction: 2.2• Boiling point: Sublimes at 800K• Resistivity: 1014 ohms m-1 (For Si 1000 ohms m-1 )

• Crystal form: FCC

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C60purple/violet

C70brick-red

C84brown

C86olive-green.

Good solvents for extraction of fullerenes from soot are toluene and xylene. Fullerenes are insoluble in water and stable at air. Thin layers of fullerenes are colored from yellow to yellow-green. Fullerene solutions colored because of

Fullerenes in Solvents

http://www.ifw-dresden.de/iff/14/forschg/fulleren/wassindfullerene/index_e.htm

π-π*-electron transitions, solutions of fullerenes are colored.

Fullerene Crystals

Face-Centered Cubic (fcc) Close-packed Structure of Bulk Solid C60

lattice constant a = 14.17 Å

2µm 200 nm

Fullerene Crystals

J. Libera and Y. Gogotsi

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Location of octahedral holes (left) and tetrahedral holes (right) relative to lattice spheres in face-centered cubic unit cell.

Structure of A3C60

Li3C60

The Big Picture of the Nanotechnology Story

Synthesis of Nanostructures

Explore the Properties

Characterization TestingExplore/speculate

Applications

Applications of Fullerenes

Buckyballs as Antioxidants

• The medical field – C Sixty, Inc., is one of the companies developing

medical applications for buckyballs. They are focusing on the ability of buckyballs to act as antioxidants, counteracting free radicals in the human body.

– A free radical is a molecule or atom that has an unpaired electron — which makes it very reactive.

– An antioxidant is a molecule that can supply an electron and neutralize a free radical.

– Merck, Inc., has obtained a licensing option on C Sixty’s antioxidant

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P.R. Birkett, et.al., J. Chem. Soc. Chem. Commun. (1993), 1230 P.R. Birkett, et.al. J. Chem. Soc. Chem. Commun. (1995), 683

Exohedral Fullerene Compounds

C60Cl6 C70Cl10

Improving medical imaging and drug delivery with buckyballs

Another potential use of buckyballs in medicine involves delivering

• elements for medical imaging• drugs directly to infected regions of the body.

One other reason buckyballs are useful for drug delivery is that they are small enough to move around inside the body quite easily.

La Atom in a Fullerene Cage(Metallofullerene)

Endohedral Fullerene Compounds

La@C60

Buckyball ApplicationsDupont and Exxon are using buckyballs to develop stronger polymers.These companies are looking at two ways of doing this: by integrating the buckyballs in the polymer with chemical bonding

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Polymerization of Fullerenes

Polymerized Rb1C60

The A1C60 compound has turned out to be much more interesting than one would have guessed. This picture shows the structure of the polymeric phase of Rb1C60, produced by slow cooling the material from the high temperature rocksalt phase. The fullerenes are now chemically bonded to form long polymer chains. This phase transition is of first order, with a transition temperature around 400K.

(C60)(C60) → C60=C=C=C58Rao, A.M., et.al., Science, 1993.

http://buckminster.physics.sunysb.edu/c60.html

C48N12

When 12 of buckminster-fullerene's 60 carbons are replaced by nitrogens, it can link up with other "buckyballs" to form a strong and springy material.

Buckyball ApplicationsDupont and Exxon are using buckyballs to develop stronger polymers.These companies are looking at two ways of doing this: by integrating the buckyballs in the polymer with chemical bondingSony is developing more efficient fuel cell membranes using buckyballs.Siemens has developed a buckyball-based light detector.Seagate is using buckyballs to develop diamond-hard coatings for computer disk drives.

Fullerene Science

Monument to C60 in Dalian, China

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Ternary “Phase” Diagram of Carbon Allotropes

NEXT

Outline• Introduction – Nanotechnology – definition, application areas…• The Element Carbon – Structure, Chemistry….• Fullerenes: Structure, Physics and Chemistry.

– Article Discussion – Kroto• Carbon Nanotubes: Structure, Synthesis and Properties.

– Article Discussion – Iijima• Carbon Nanotubes: Applications.

– Article Discussion – Wong• Graphene – a new generation of materials.

– Article Discussion – Novoselov

Testing and Characterization on Nanoscale• Part 1. Electron microscopy (SEM, TEM)• Part 2. Raman microspectroscopy….

– Article Discussion – Rao• Part 3. Atomic Force Microscopy (AFM)• Part 4. Nanoindentation• Part 5. Study of properties (optical, electrical)

Introduction to MEMs

Carbon Nanotubes Timetable

ISI Web of Science

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• Carbon nanotubes can be considered as graphene sheets rolled up into seamless cylinders

Rolling Directions of a Graphene Sheet

Arrows are showing two different rolling directions which gives rise to armchair and zigzag nanotube.

Three Archetypal SWNT Nanotubes

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Chiral and Zigzag Nanotubes