02-10-2012, 10:23 AM
DIFFERENT METHODS OF CARBON NANOTUBE SYNTHESIS
[attachment=34981]
Methods of carbon nanotube synthesis'
There are three main synthesis methods, namely
1. Arc discharge,
2.The laser ablation and
3. The chemical vapour deposition (CVD)
In the early stage of the nanotube production the first two methods were utilized mainly for the production of SWNTs while the third one produced mainly MWNTs.
Carbon nanotubes (CNTs) are characterized as a graphite sheet rolled-up to form a tube, for example a single-walled tube (SWNT). When two or more concentric tubes are placed one into another, multi-walled carbon nanotube (MWNT) is formed.
ARC DISCHARGE METHOD
First & simplest method to synthesis CNT
Two pure graphite electrodes are connected to DC generator. An inert gas(helium) is added to the chamber which do not react with carbon.
Electric current is run through electrodes and therefore carbon is deposited into cathode from anode and CNT are shaped in the middle. Inner tube is about 1-3nm & outer tube in MWNT 10nm in diameter.
Applying a magnetic field around the arc plasma for alignment purposes. A magnetic field have a high purity and fewer defect’s electronic devices as nanowires for device fabrication. In this method the arc discharge technique is done by plasma rotating(5000rpm). As a result increased plasma volume more stable and homogenous plasma has been observed. Temp around 1025*C. No catalyst is used in this method.
LASER ABLATION
Laser is used to vapourize carbon from graphite a high temperature reactor at 1200*C. Here we use He or Argon (inert gas). This process is similar to arc discharge method but it require high temperature.
Continuous Laser
Pulsed laser
Difference – pulsed laser requires high light density
If we use pure graphite electrodes we can obtain MWNT’s, but to have uniform SWNT’s a mixture of graphite with Co, Ni, Fe.
Yield of this process is low. It contain CNT along with carbon nanoparticles. So it is not used for industrial application.
[attachment=34981]
Methods of carbon nanotube synthesis'
There are three main synthesis methods, namely
1. Arc discharge,
2.The laser ablation and
3. The chemical vapour deposition (CVD)
In the early stage of the nanotube production the first two methods were utilized mainly for the production of SWNTs while the third one produced mainly MWNTs.
Carbon nanotubes (CNTs) are characterized as a graphite sheet rolled-up to form a tube, for example a single-walled tube (SWNT). When two or more concentric tubes are placed one into another, multi-walled carbon nanotube (MWNT) is formed.
ARC DISCHARGE METHOD
First & simplest method to synthesis CNT
Two pure graphite electrodes are connected to DC generator. An inert gas(helium) is added to the chamber which do not react with carbon.
Electric current is run through electrodes and therefore carbon is deposited into cathode from anode and CNT are shaped in the middle. Inner tube is about 1-3nm & outer tube in MWNT 10nm in diameter.
Applying a magnetic field around the arc plasma for alignment purposes. A magnetic field have a high purity and fewer defect’s electronic devices as nanowires for device fabrication. In this method the arc discharge technique is done by plasma rotating(5000rpm). As a result increased plasma volume more stable and homogenous plasma has been observed. Temp around 1025*C. No catalyst is used in this method.
LASER ABLATION
Laser is used to vapourize carbon from graphite a high temperature reactor at 1200*C. Here we use He or Argon (inert gas). This process is similar to arc discharge method but it require high temperature.
Continuous Laser
Pulsed laser
Difference – pulsed laser requires high light density
If we use pure graphite electrodes we can obtain MWNT’s, but to have uniform SWNT’s a mixture of graphite with Co, Ni, Fe.
Yield of this process is low. It contain CNT along with carbon nanoparticles. So it is not used for industrial application.