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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. Metallic conductor (graphite). Semiconductor (diamond).
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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
Metallic conductor (graphite) Semiconductor (diamond) Insulating Polymer (hydrocarbon chains) 3-D 1-D 0-D 2-D Carbon Nanostructures Variety of properties Variety of structures
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
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 e- C+ Anode Cathode Nanotube deposit • Combustion synthesis • Burn hydrocarbon at low pressure
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
Carbon Nanotubes • 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
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)