Supercomputer simulations reveal strongest carbon nanotubes

September 17, 2001

A team of researchers lead by Vincent Crespi, the Downsborough Associate Professor of Physics at Penn State University, has used computer simulations to discover carbon fibers with mechanical strength comparable to that of diamond. In a paper published in today's Physical Review Letters, Crespi, graduate student Dragan Stojkovic, and recent Ph.D. graduate Peihong Zhang report that they discovered incredibly strong and stiff carbon tubes about 0.4 nanometers in diameter. The so-called nanotubes could theoretically be made from simple starting materials.

"This new fiber hasn't been synthesized yet," said Crespi, "but several physicists and chemists are interested in making them, and they may prove very useful in nanotechnology applications."

Using supercomputers at the San Diego Supercomputer Center (SDSC), the University of Michigan, and the University of Texas, Crespi's team simulated the electronic states and total energies of various carbon molecules. This computationally intensive approach to chemistry research at colleges and universities has been made possible with supercomputers provided by the National Science Foundation under its National Partnership for Advanced Computational Infrastructure (NPACI). SDSC, which is on the campus of the University of California, San Diego, is the leading-edge site for NPACI.

The nanotube discovery by Crespi's team was made serendipitously while its members were studying unrelated features of carbon compounds. "This is one of those sideways inspirations that comes when you're looking at one thing and you suddenly realize it has a different application," said Crespi. He immediately adjusted the focus of his simulations. "Actually, I was motivated to make this strong nanotube the moment I realized it could be done."

Commercially available "carbon fiber" is 6 to 10 micrometers thick, or one-fifth the thickness of a human hair, and made of carbon-containing polymers. It is used to make items ranging from golf clubs and tennis rackets to bicycle frames and racing yachts. While this type of carbon fiber is weaker than carbon nanotubes, it is easy to produce in large quantities. Manufacturers weave it into sheets, bars, tubes, and other shapes - often in several overlapping layers to increase their strength. Binders such as epoxy resins are often applied to the sheets to connect the fibers to one another for additional strength.

Carbon nanotubes are 10,000 times thinner than commercial carbon fiber. Researchers make them using chemical vapor deposition, a standardized industrial technology in which simple ingredients self assemble. Crespi said vapor deposition also would most likely be used to make the much stronger version of nanotube that his group discovered.

Not all nanotubes have the same properties. The smallest diameter nanotubes created to date have a circumference of about 10 carbon atoms. These tubes are not stable and must be grown within larger-diameter carbon tubes or in tiny cylindrical holes in special crystals known as zeolites.

The Penn State team recently made a key discovery that a particular type of tetrahedral carbon atom--one with three weakly bonded groups and a relatively tightly bonded group--had special properties. When connected to one another, these molecules have carbon-carbon bonding angles of about 109.5 degrees, which also is the ideal bonding angle of carbon atoms with tetrahedral symmetry. In addition, the stiff, small-diameter, and chemically stable carbon nanotube discovered by the researchers has a circumference of only six carbon atoms, or about 0.4 nanometers--the smallest diameter theoretically possible.

"Based on our calculations, these new nanotubes are about 40 percent stronger than the other nanotubes formed using the same number of atoms," said Crespi. "In fact, the nanotubes we simulated may well be the stiffest one-dimensional systems possible."
This research was funded by the National Science Foundation and the Army Research Office.

A high-resolution computer-generated color image looking down the core of a carbon nanotube is available on the Web at

A computer-generated color image looking down the core of a carbon nanotube. In the ultra-small-scale world of materials science, nanotubes and nanowires have become the building blocks of the future. Image courtesy of Vincent Crespi, Penn State.

Vincent Crespi, Pennsylvania State University 814-863-0163,

Barbara K. Kennedy, Pennsylvania State University, 814-863-4682 or 814-863-8453,

Rex Graham, San Diego Supercomputer Center, 858-822-5408,

Penn State

Related Carbon Nanotubes Articles from Brightsurf:

How plantains and carbon nanotubes can improve cars
Researchers from the University of Johannesburg have shown that plantain, a starchy type of banana, is a promising renewable source for an emerging type of lighter, rust-free composite materials for the automotive industry.

New production method for carbon nanotubes gets green light
A new method of producing carbon nanotubes -- tiny molecules with incredible physical properties used in touchscreen displays, 5G networks and flexible electronics -- has been given the green light by researchers, meaning work in this crucial field can continue.

Growing carbon nanotubes with the right twist
Researchers synthetize nanotubes with a specific structure expanding previous theories on carbon nanotube growth.

Research shows old newspapers can be used to grow carbon nanotubes
New research has found that old newspaper provide a cheap and green solution for the bulk production of single walled carbon nanotubes.

Clean carbon nanotubes with superb properties
Scientists at Aalto University, Finland, and Nagoya University, Japan, have found a new way to make ultra-clean carbon nanotube transistors with superior semiconducting properties.

Dietary fiber effectively purifies carbon nanotubes
A dietary fiber can help separate out semiconducting carbon nanotubes used for making transistors for flexible electronics.

Why modified carbon nanotubes can help the reproducibility problem
Scientists at Tokyo Institute of Technology (Tokyo Tech) conducted an in-depth study on how carbon nanotubes with oxygen-containing groups can be used to greatly enhance the performance of perovskite solar cells.

Tensile strength of carbon nanotubes depends on their chiral structures
Single-walled carbon nanotubes should theoretically be extremely strong, but it remains unclear why their experimental tensile strengths are lower and vary among nanotubes.

New study reveals carbon nanotubes measurement possible for the first time
Swansea University scientists report an entirely new approach to manipulation of carbon nanotubes that allows physical measurements to be made on carbon nanotubes that have previously only been possible by theoretical computation.

Neural networks will help manufacture carbon nanotubes
A team of scientists from Skoltech's Laboratory of Nanomaterials proposed a neural-network-based method for monitoring the growth of carbon nanotubes, preparing the ground for a new generation of sophisticated electronic devices.

Read More: Carbon Nanotubes News and Carbon Nanotubes Current Events is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to