04-02-2012, 04:12 PM
CARBON NANOTUBES
[attachment=17147]
NANOSCIENCE
.A nanometre (nm) is one thousand millionth of a metre.
.For comparison, a single human hair is about 80,000 nm wide
.Definition for Nanoscience: The study of phenomena and manipulation of materials at atomic, molecular and micro molecular scales, where properties differ significantly from those at a larger scale.
.Nanotechnology is the application of these nanostructures into useful nanoscale devices.
.People are interested in the nanoscale (range:100nm-approx 0.2nm) because it is at this scale that the properties of materials can be very different from those at a larger scale.
Arc Discharge
An inert gas such as He or Ar is used as the atmosphere for the reaction (pressure of 100-1000 torr)
Nanotubes and C60 forms on the cathode, along with soot and fullerenes.
SWCNTs could only be formed by adding metal catalyst to the anode.
Chemical Vapor Deposition CVD
Substrate of layer of catalyst particles(Ni,Co,Fe)
Carbon source in the gas phase (methane, CO and acetylene, Ethanol) and heated to 500-1200 oC .
The energy source is used to "crack" the molecule into reactive atomic carbon. Then, the carbon diffuses towards the substrate, which is heated and coated with a catalyst (Ni, Fe or Co) where it will bind. Carbon nanotubes will be formed if the proper parameters are maintained.
Thermal annealing results in cluster formation on the substrate, from which the nanotubes will grow.
Excellent alignment, as well as positional control on nanometre scale.
Control over the diameter, as well as the growth rate of the nanotubes can also be maintained. The appropriate metal catalyst can preferentially grow single rather than multi-walled nanotubes.
[attachment=17147]
NANOSCIENCE
.A nanometre (nm) is one thousand millionth of a metre.
.For comparison, a single human hair is about 80,000 nm wide
.Definition for Nanoscience: The study of phenomena and manipulation of materials at atomic, molecular and micro molecular scales, where properties differ significantly from those at a larger scale.
.Nanotechnology is the application of these nanostructures into useful nanoscale devices.
.People are interested in the nanoscale (range:100nm-approx 0.2nm) because it is at this scale that the properties of materials can be very different from those at a larger scale.
Arc Discharge
An inert gas such as He or Ar is used as the atmosphere for the reaction (pressure of 100-1000 torr)
Nanotubes and C60 forms on the cathode, along with soot and fullerenes.
SWCNTs could only be formed by adding metal catalyst to the anode.
Chemical Vapor Deposition CVD
Substrate of layer of catalyst particles(Ni,Co,Fe)
Carbon source in the gas phase (methane, CO and acetylene, Ethanol) and heated to 500-1200 oC .
The energy source is used to "crack" the molecule into reactive atomic carbon. Then, the carbon diffuses towards the substrate, which is heated and coated with a catalyst (Ni, Fe or Co) where it will bind. Carbon nanotubes will be formed if the proper parameters are maintained.
Thermal annealing results in cluster formation on the substrate, from which the nanotubes will grow.
Excellent alignment, as well as positional control on nanometre scale.
Control over the diameter, as well as the growth rate of the nanotubes can also be maintained. The appropriate metal catalyst can preferentially grow single rather than multi-walled nanotubes.
