Special Focus: Carbon Nanostructures
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Transcript of Special Focus: Carbon Nanostructures
Special Focus:Carbon
Nanostructures
Carbon Nanostructures– Buckyballs– Nanotubes
• SWNT & MWNT (single-walled nanotubes & multi-walled
nanotubes)
– Graphene thin layers
http://education.mrsec.wisc.edu/Edetc/pmk/pages/bucky.html
Carbon NanostructuresVariety of properties
Variety of structures
0-D
Metallic conductor (graphite)
Semiconductor (diamond)
Insulating Polymer (hydrocarbon chains)
1-D2-D
3-D
Carbon Fullerenes• 0-dimensional carbon structure• Usually C60, but also refers to C70, C76, Cn (n > 60)• Every carbon site on C60 is equivalent
– Bonded to three other carbons– average bond is 1.44 Å (C-C is 1.46 Å; C=C is 1.40 Å)
• 20 hexagonal faces; 12 pentagonal faces• Diameter: 7.10 Å (7.1 x 10-10 m)
Buckminster Fuller (1895-1983):Architect, engineer, inventor; Developed the geodesic dome
Epcot Center in Disneyworld
Climatron at the Missouri Botanical Garden
Biosphere Museum in Canada
• The shape of the geodesic dome encloses the greatest volume while taking up the least surface area.
• Fuller hoped the design would produce large numbers of inexpensive homes for soldiers returning from WWII.
• The building can withstand high winds such as those found in hurricanes.
Synthesis of Fullerenes• Laser ablation (vaporizing graphite with a laser)• Plasma arcing of graphite or coal
– Fullerenes found in the soot
Anode Cathode
C+
Nanotube deposit
• Combustion synthesis– Burn hydrocarbon at low pressure
e-
Demo: Laser Pointer, watch plate, Charcoal briquette!
• Single-Walled Carbon Nanotubes (SWCNT; SWNT)• Multi-Walled Carbon Nanotubes (MWCNT; MWNT)
• How to make them:– Arc evaporation (plasma arcing)– Laser ablation– PECVD (plasma-enhanced chemical vapor
deposition)– Electrochemical methods
http://www.extremetech.com/extreme/137555-mit-creates-carbon-nanotube-pencil-doodles-some-electronic-circuits?print
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Carbon Nanotubes
(a) Armchair
(b) Zigzag
(c) Chiral
Properties of Carbon Nanotubes• Mechanical
– Stiff and robust structures• C-C bonds in graphite (and nanotubes) is the one
of the strongest bonds in nature– Flexible; do not break when bent
• Conductivity– Extremely high thermal conductivity– Extremely high electrical conductivity
• Potential Applications:- catalysis - hydrogen storage - biological cell electrodes- resistors - flow sensors - electron field emission tips- electronic/mechanical devices - scanning probe tips
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Carbon Nanotube Applications:NEMS: Nanoelectricalmechanical
systems“Nantero is a nanotechnology
company using carbon nanotubes for the development of next-generation semiconductor devices...
In the field of memory, Nantero is developing NRAM™, a high-density nonvolatile Random Access Memory.”
Gold plate ~ (100 nm)2
attached to outer shell of suspended MWCNT (on Si wafer)“electrostatically rotate the outer shell relative to the inner core”
WATCH CLIP FROM “NOVA: Making Things Stronger” about Carbon Nanotubes (Scene Selection)