|
Carbon nanotube measurements: latest in NIST 'how-to' series
April 16, 2008The National Institute of Standards and Technology (NIST), in collaboration with the National Aeronautics and Space Administration (NASA), has published detailed guidelines* for making essential measurements on samples of single-walled carbon nanotubes (SWCNTs). The new guide constitutes the current "best practices" for characterizing one of the most promising and heavily studied of the new generation of nanoscale materials.
The nanotubes are essentially cylinders of carbon atoms with a wall only one atom thick and a diameter of a couple of nanometers-but lengths up to several million times their diameter. (Think of a soup can about 100 kilometers tall.) Because of their unique electronic, thermal, optical and mechanical properties they are being studied for a wide-and expanding-range of applications, including ultrastrong fibers for nanocomposite materials, circuit elements in molecular electronics, hydrogen storage components for fuel cells and light sources for compact, efficient flat-panel displays. One basic problem is assuring the quality and purity of SWCNT materials. All known techniques for producing these tiny tubes also produce large quantities of nanojunk: simple graphite and carbon soot often encapsulating small metal particles used to catalyze the nanotube synthesis process. (See, for example, "NIST Laser-Based Method Cleans Up Grubby Nanotubes", Tech Beat Dec. 1, 2006.)
Accurate, reliable and preferably rapid measurement techniques are needed to optimize production processes to create more product and less impurities. These will help to control cleaning and purifying processes and ultimately to improve the confidence of buyers and sellers of SWCNT materials. Beginning in 2003, NIST and NASA researchers started addressing the problem by sponsoring a series of workshops devoted to nanotube measurements. The NIST "Recommended Practice Guide" on Measurement Issues in Single Wall Carbon Nanotubes grew out of second workshop in 2005, and represents what industry, government and academic researchers regard as the most useful and accurate measurement techniques for characterizing the purity of SWCNT samples. The techniques discussed include thermogravimetric analysis; near-infrared spectroscopy; Raman spectroscopy and optical, electron and scanned probe microscopy. Researchers from the NASA Johnson Space Center, the University of California at Riverside, Boston University and the NASA Langley Research Center contributed to the guide.
The techniques described in the guide were proposed as the basis for international standards for nanotube characterization. A collaborative effort that includes the US, China, Japan, and Korea is now underway under the International Organization for Standardization (ISO) to develop these techniques into standards that will help ensure uniform characterization metrics used when buying and selling nanotubes. The editors caution that in the fast-moving field of carbon nanotubes, characterization methods will need to be updated periodically.
The NIST Recommend Practice Guides are a set of publications devoted to specific, challenging measurement issues faced in industry and research. Online copies of Measurement Issues in Single Wall Carbon Nanotubes and other guides in the series are available at The "How To Measure" Book Series.
###
* S. Freiman, S. Hooker, K. Migler and S. Arepalli (eds.). Measurement Issues in Single Wall Carbon Nanotubes. NIST Special Publication 960-19, March 2008.
National Institute of Standards and Technology (NIST)
The techniques described in the guide were proposed as the basis for international standards for nanotube characterization. A collaborative effort that includes the US, China, Japan, and Korea is now underway under the International Organization for Standardization (ISO) to develop these techniques into standards that will help ensure uniform characterization metrics used when buying and selling nanotubes. The editors caution that in the fast-moving field of carbon nanotubes, characterization methods will need to be updated periodically.
The NIST Recommend Practice Guides are a set of publications devoted to specific, challenging measurement issues faced in industry and research. Online copies of Measurement Issues in Single Wall Carbon Nanotubes and other guides in the series are available at The "How To Measure" Book Series.
###
* S. Freiman, S. Hooker, K. Migler and S. Arepalli (eds.). Measurement Issues in Single Wall Carbon Nanotubes. NIST Special Publication 960-19, March 2008.
National Institute of Standards and Technology (NIST)
Carbon Nanotubes News and Current Carbon Nanotubes Events RSSLLNL researchers peer into water in carbon nanotubes
Researchers have identified a signature for water inside single-walled carbon nanotubes, helping them understand how water is structured and how it moves within these tiny channels.
The fight for the best quantum bit (qubit)
Our results give us, for the first time, the possibility to understand the interaction between just two electrons placed next to each other in a carbon nanotube.
Perfecting a solar cell by adding imperfections
Nanotechnology is paving the way toward improved solar cells. New research shows that a film of carbon nanotubes may be able to replace two of the layers normally used in a solar cell, with improved performance at a lower cost. Researchers have found a surprising way to give the nanotubes the properties they need: add defects.
Secret ingredient: nanoparticles aid bone growth
In the first study of its kind, bioengineers and bioscientists at Rice University and Radboud University in Nijmegen, Netherlands, have shown they can grow denser bone tissue by sprinkling stick-like nanoparticles throughout the porous material used to pattern the bone.
NASA Scientists Pioneer Method for Making Giant Lunar Telescopes
Scientists working at NASA's Goddard Space Flight Center in Greenbelt, Md., have concocted an innovative recipe for giant telescope mirrors on the Moon. To make a mirror that dwarfs anything on Earth, just take a little bit of carbon, throw in some epoxy, and add lots of lunar dust.
Brown researchers work toward ending cartilage loss
Scientists have long wrestled with how to aid those who suffer cartilage damage and loss. One popular way is to inject an artificial gel that can imitate cartilage's natural ability to act as the body's shock absorber. But that solution is temporary, requiring follow-up injections.
Nanoparticles assemble by millions to encase oil drops
In a development that could lead to new technologies for cleaning up oil spills and polluted groundwater, scientists at Rice University have shown how tiny, stick-shaped particles of metal and carbon can trap oil droplets in water by spontaneously assembling into bag-like sacs.
Carbon nanoribbons could make smaller, speedier computer chips
Stanford chemists have developed a new way to make transistors out of carbon nanoribbons. The devices could someday be integrated into high-performance computer chips to increase their speed and generate less heat, which can damage today's silicon-based chips when transistors are packed together tightly.
Spin control: New technique sorts nanotubes by length
Researchers at the National Institute of Standards and Technology (NIST) have reported a new technique to sort batches of carbon nanotubes by length using high-speed centrifuges.
Go Speed Racer! Revving up the world's fastest nanomotors
In a "major step" toward a practical energy source for powering tomorrow's nanomachines, researchers in Arizona report development of a new generation of sub-microscopic nanomotors that are up to 10 times more powerful than existing motors. Their study is scheduled for the May 27 issue of ACS Nano, a monthly journal.
More Carbon Nanotubes News Articles
| © 2008 BrightSurf.com |