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Chapter 10: Nanostructures and Solids with

Low-Dimensional Properties

Nanoscience: the study of phenomena and manipulation of materials at atomic, molecular, and macromolecular scales, where properties differ significantly from those at larger scale.

Nanotechnology: the production and application of structures, devices, and systems for controlling shape and size at the nanometer scale.

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How big is a nanometer?

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Using Light to See

Using Electrons to See

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Touching the surface

www.nature.com/nmat/journal/v6/n9/fig_tab/nmat1957_F1.html

Nanoparticle morphology

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Electronic Structure

bulk quantum well

quantum wire quantum dot

Electronic Structure

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Semiconducting nanotube

Electronic Structure

Optical Properties

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Nanoparticles CdSe

Smallest nanoparticles resemble molecular absorptions

Larger nanoparticles have featureless absorptions resemble bulk solid

Nanogold

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Optical properties

Zinc oxide

Magnetic properties

Solid Dc (nm)Fe 14Co 70Ni 55Fe3O4 55

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Physical Properties:

Melting Point

macroscale nanoscaleMajority of atoms are: almost all inside the

objectsplit between the inside and the surface

Changing an object’s size:

has minimal effect on the % of atoms on the surface

has a substantial effect on the % of atoms on the surface

The melting point: doesn’t depend on size

is lower for smaller particles

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Fabrication Methods

Self Assembly by Crystal Growth

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Graphite

Intercalation Compounds of Graphite

KC8

CaC8

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chevroletvoltage.com

“Each Volt’s battery cell contains a carbon anode (the negative electrode), a manganese-based cathode (the positive electrode) and a safety reinforced separator, which provides the medium for the transfer of electrical charge ions between the anode and the cathode inside the battery cell.”

Buckminster Fullerene

K3C60

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Armchair nanotubes are metallic. Zig-zag and chiral nanotubes can be either metallic or semiconducting.

zig-zag armchair chiral

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Arc-discharge

Laser Furnace

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•Hydrocarbon vapor passed through a tube furnace. •SWNTs or MWNTs depends on size and temperature of catalyst (Fe, Ni with NH3). •Low-temperature (600-900°C) yields MWNTs, higher temperature (900-1200°C) favors SWNTs.

Chemical vapor deposition

Carbon Nanotube Growth

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Problems with CNT production•Mixture of metallic and semiconducting •Alignment and positioning

A breakthrough?•ST-cut single crystal quartz substrates •ethanol/methanol as carbon source •Cu nanoparticles as catalysts

Results•1.55 to 1.78 nm diameter SWNT •95% semiconducting •CNT aligned

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Teflon Coated CNT Forest

Spinning Carbon Nanotubes

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Space Elevator

Space Elevator Cable

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Photolithography

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Polyacetylene

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Conducting polymers: Repeating units

Bonding in Polyacetylene

E

Peierls’ Theorem

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Metal

Conjugated polymer

Glass

ITO

Organic Polymer LED

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Gao, F. G.; Bard, A. J. J. Am. Chem. Soc. 2000, 122, 7426.

Organic LED

www.mrsec.wisc.edu/Edetc/SlideShow/slides/oLED/oLEDspin_mov.htmlwww.mrsec.wisc.edu/Edetc/SlideShow/slides/oLED/oLEDevap_mov.html

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OLED vs. LCD

Advantages• no backlight or polarizer• wider viewing angle• lower power consumption• easier processing• thinner and lighter• faster response time

Disadvantages• lifetime and color stability• newer technology

OLED TV

Sony 11-inch OLED TV is 3 mm thick with a 1,000,000:1 contrast ratio.

OLED MP3/Video Player

Cowon S9 16 GB

Nokia 7500 Prism Tri-Band GSM Phone

OLED Phone

iriver Clix Rhapsody

Keyboard Extender

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Flexible OLED and Roll-to-Roll Manufactured OLEDs

Molecular metals – 1D

molecular nanowires

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Molecular metals – 2D

TMTSF BEDT-TTF

β-(BEDT-TTF)2I3

Polymers and Ionic Conduction Rechargeable Lithium Batteries

Li(s) Li+ (solv) + e- and xLi+(solv) + TiS2(s) + xe- LixTiS2(s)

Overall: xLi(s) + TiS2(s) LixTiS2(s)

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AFM Probe Tip 600 nm deep trenches;250 nm wide

mage using conventional tip