Nanotech References
1. Small Times Magazine
2. “Improved Synthesis of carbon nanotubes with junctions and of single-wall carbon nanotubes” F L Deepak et.al, J. Chem. Sci., Vol. 118, No.1, Jan 2006 pp.9-114.
In presence of water vapor, pyrolysis of organic vapor yielded single walled CNTs as well as relatively narrow diameter CNT with Y junctions. The absence of water vapor generates CNTs with T and Y junctions. Multiwall junctions were seen in water vapor free zones.
3. “Water Assisted highly efficient synthesis of Impurity-free single-walled carbon nanotubes.” K Hata., November 19, 2004 Vol 306 Science.
Authors searched for a weak oxidizer to remove amorphous carbon that would not harm CNT structure. The addition of water was instrumental in growing single wall CNT.
4. “Aligned carbon nanotube growth under oxidative ambient”, A Cao, et.al.,
Water vapor was added during CNT fabrication to clean but was found to also generate CNT defects. Walls and tube ends were found broken by the addition of water vapor. 17% water vapor generated bent tubes.
5. Carbon Nanotube Purification, United States Patent # 6,972,056 B1 Delzeit et.al. Dec 6, 2005
Patent describes method for cleaning and removal of amorphous carbon and other residues that arise in the growth of Carbon nanotube arrays. Hydroxyl groups react with residues to produce partly or fully dissolved or hydrogenated or hydroxylizated products that can be removed or separated from the CNT array. Pure oxygen in thermal or plasma environments non-selectively attacks CNT material. Toxic gases such as halogens remove amorphous carbon, but require use and disposal of hazardous substances and generates hazardous waste.
Oxygen must be purged from the chamber before adding water vapor. Water vapor is added to the chamber from 50C to 850C. The vapor is heated and exposed to electromagnetic radiation. The water vapor decomposes and reacts to produce removable products.
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