Single Walled Nanotube (SWNT) Techniques

On the "Nanotubes" page I have already mentioned the most common techniques used in the production of nanotubes. For a quick reminder here is a list of the common techniques.

1. Carbon Arc-Discharge (AD)
2. Chemical Vapor Deposition (CVD)
3. Laser Pyrolysis (LP)
4. Pulse Laser Vaporization (PLV)

In this section, we will explore all the techniques in-depth and I will provide you with some examples to better illustrate the techniques shown above. Please note, there are many techniques used in the production of single walled nanotubes (SWNT) but on this site I will only mention the techniques used in common practice. With that said, please click on the links (AD, PLV, CVD, LP) to start exploring each technique.

The following table is a summary of only three techniques mentioned above:

Method:	Carbon Arc-Discharge	Chemical Vapor Deposition	Pulse Laser Vaporization
Who:	Ebbesen and Ajayan, NEC, Japan 1992	Endo, Shinshu University, Nagano, Japan	Smalley, Rice, 1995
How:	Connect two graphite rods to a power supply, place them a few millimetres apart, and throw the switch. At 100 amps, carbon vaporizes and forms a hot plasma.	Place substrate in oven, heat to 600° C, and slowly add a carbon-bearing gas such as methane. As gas decomposes it frees up carbon atoms, which recombine in the form of NT's	Blast graphite with intense laser pulses; use the laser pulses rather than electricity to generate carbon gas from which the NT's form; try various conditions until hit on one that produces prodigious amounts of SWNT's
Yield:	30 to 90%	20 to 100%	Up to 70%
SWNT:	Short tubes with diameters of 0.6 - 1.4 nm	Long tubes with diameters ranging from 0.6-4 nm	Long bundles of tubes (5-20 microns), with individual diameter from 1-2 nm.
MWNT:	Short tubes with inner diameter of 1-3 nm and outer diameter of approximately 10 nm	Long tubes with diameter ranging from 10-240 nm	Not very much interest in this technique, as it is too expensive, but MWNT synthesis is possible.
Pros:	Can easily produce SWNT, MWNT's. SWNT's have few structural defects; MWNT's without catalyst, not too expensive, open air synthesis possible	Easiest to scale up to industrial production; long length, simple process, SWNT diameter controllable, quite pure	Primarily SWNT's, with good diameter control and few defects. The reaction product is quite pure.
Cons:	Tubes tend to be short with random sizes and directions; often needs a lot of purification	NT's are usually MWNT's and often riddled with defects	Costly technique, because it requires expensive lasers and high power requirement, but is improving

Note: This section is still under heavy maintenance, some of the links may not work because they have not been activated by me yet. The only link that works is PLV.