Carbon Nanotube Measurements: Latest in NIST 'How-To' Series

Apr 15, 2008
Carbon Nanotube Measurements: Latest in NIST 'How-To' Series
Scanning electron microscope image of "cleaned" carbon nanotubes at NIST (color added for clarity.) Credit: NIST

The National Institute of Standards and Technology, in collaboration with the National Aeronautics and Space Administration, 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.

Citation: S. Freiman, S. Hooker, K. Migler and S. Arepalli (eds.). Measurement Issues in Single Wall Carbon Nanotubes. NIST Special Publication 960-19, March 2008.

Source: National Institute of Standards and Technology

Explore further: Graphene and diamonds prove a slippery combination

Related Stories

Carbon nanothreads from compressed benzene

May 20, 2015

A new carbon nanomaterial – the thinnest possible one-dimensional thread that still retains a diamond-like structure – was created by the controlled, slow compression and decompression of benzene. The ...

Recommended for you

Graphene and diamonds prove a slippery combination

4 hours ago

Scientists at the U.S. Department of Energy's Argonne National Laboratory have found a way to use tiny diamonds and graphene to give friction the slip, creating a new material combination that demonstrates ...

Artificial muscles get graphene boost

May 22, 2015

Researchers in South Korea have developed an electrode consisting of a single-atom-thick layer of carbon to help make more durable artificial muscles.

How to make continuous rolls of graphene

May 21, 2015

Graphene is a material with a host of potential applications, including in flexible light sources, solar panels that could be integrated into windows, and membranes to desalinate and purify water. But all ...

Printing 3-D graphene structures for tissue engineering

May 19, 2015

Ever since single-layer graphene burst onto the science scene in 2004, the possibilities for the promising material have seemed nearly endless. With its high electrical conductivity, ability to store energy, ...

User comments : 0

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.