Featured Research

from universities, journals, and other organizations

Measuring The Tiniest Of Structures: Researchers Compare Bending Strength Of Individual Carbon Nanotubes

Date:
October 18, 2000
Source:
Georgia Institute Of Technology
Summary:
Researchers at the Georgia Institute of Technology have used a straightforward technique based on mechanical resonance induced by an oscillating electrical voltage to measure the comparative bending strength of tiny carbon nanotubes produced by two competing processes.

Researchers at the Georgia Institute of Technology have used a straightforward technique based on mechanical resonance induced by an oscillating electrical voltage to measure the comparative bending strength of tiny carbon nanotubes produced by two competing processes.

The National Science Foundation-sponsored work, which also correlates the strength measurements to observed defects, provides information that will be important in helping materials scientists select the best variety of nanotube for new applications now under development. The high strength, light weight and unique electronic properties of multiwalled carbon nanotubes have led to potential applications as diverse as ultra-light composites and low-power field emission displays.

The researchers have used the same technique to study other fiber-like structures that are too small to be measured by conventional testing methods.

"We are able to make a quantitative comparison, with a real number to describe how much the bending modulus differs," said Dr. Z.L. Wang, a Georgia Tech professor of materials science. "This work provides materials scientists the information needed to make a choice, and gives the first set of data for theoretical scientists to model individual nanotubes."

With colleagues Walter de Heer and Zhigang Bai of Georgia Tech, Liming Dai and Mei Gao from CSIRO Molecular Science in Australia, and Ruiping Gao of the University of Science and Technology in Beijing, Wang compared nanotubes produced by traditional high-temperature carbon arc discharge to nanotubes grown through a lower-temperature catalyst-assisted pyrolysis process. In the journal Physical Review Letters, the researchers report on the dramatic strength differences caused by point and volume defects in the catalytically-grown nanotubes.

Researchers had known that the catalytically-grown tubes were weaker than comparable structures grown in carbon arcs, and had made bulk measurements that produced an average strength value. But producing data for individual tubes gives scientists better information to predict performance.

Wang believes the catalytically-grown nanotubes may offer advantages for ultra lightweight composites, where the defects could help interlock the tubes to prevent pulling out of the finished part. On the flip side, however, those defects could cause problems in electronic applications such as field emission electrodes where current flow could cause uneven heating in the narrow regions.

Those considerations must be weighed against the cost of production for both processes, the speed at which the catalytically-grown tubes can be "grown like grass on a substrate," and the relatively low yield of the carbon arc method, Wang noted.

"Both types have advantages depending on the specific application," he noted.

The measurement technique begins by gluing a single nanotube just a few hundredths of a micron in diameter and 5 - 20 microns long to a tiny gold ball in a specially-prepared transmission electron microscope (TEM) sample holder. The tube is aligned near another gold ball, and an oscillating electrical voltage is applied. Adjusting the frequency of the voltage allows the researchers to induce a mechanical resonance in the tube that can be observed and measured.

By knowing the outer diameter, inner diameter, length and density of the nanotube under study, the researchers can determine the bending modulus from the frequency at which the tube resonates. Because the oscillating tube can be observed in the TEM, the strength can be correlated to visible defects.

"This is a very simple and straightforward way to measure these properties," Wang said. "It has a wide application as a general technique for making mechanical property measurements of any nanofibers."

Because carbon nanotubes are so light and strong, they could offer significant advantages over conventional carbon fiber reinforcement in the manufacture of composite materials.

"This could be a big gain for space technology," Wang said. "In composites, carbon nanotubes can reduce weight by a factor of 5-10, while increasing the strength by a factor of 5-10 compared to a conventional carbon fiber matrix."

Beyond the carbon nanotubes, Georgia Tech researchers have used the TEM technique to measure the properties of biaxially structured silicon carbide-silica nanowires.

In a paper accepted for publication in Applied Physics Letters, J.L. Gole, Z.R. Dai, Z.G. Bai and Wang, all from Georgia Tech, and R.P. Gao from the University of Science and Technology in Beijing, describe measuring the Young's modulus of a single fiber produced by growing two different materials together. These biaxially structured silicon carbide-silica nanowires could have important applications in nanoelectronics and high-strength composites.

The measurements were made in the Center for Nanoscience and Nanotechnology at Georgia Tech. Support for the work was also provided by the China NSF.


Story Source:

The above story is based on materials provided by Georgia Institute Of Technology. Note: Materials may be edited for content and length.


Cite This Page:

Georgia Institute Of Technology. "Measuring The Tiniest Of Structures: Researchers Compare Bending Strength Of Individual Carbon Nanotubes." ScienceDaily. ScienceDaily, 18 October 2000. <www.sciencedaily.com/releases/2000/10/001013074200.htm>.
Georgia Institute Of Technology. (2000, October 18). Measuring The Tiniest Of Structures: Researchers Compare Bending Strength Of Individual Carbon Nanotubes. ScienceDaily. Retrieved July 28, 2014 from www.sciencedaily.com/releases/2000/10/001013074200.htm
Georgia Institute Of Technology. "Measuring The Tiniest Of Structures: Researchers Compare Bending Strength Of Individual Carbon Nanotubes." ScienceDaily. www.sciencedaily.com/releases/2000/10/001013074200.htm (accessed July 28, 2014).

Share This




More Matter & Energy News

Monday, July 28, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Europe's Highest Train Turns 80 in French Pyrenees

Europe's Highest Train Turns 80 in French Pyrenees

AFP (July 25, 2014) Europe's highest train, the little train of Artouste in the French Pyrenees, celebrates its 80th birthday. Duration: 01:05 Video provided by AFP
Powered by NewsLook.com
TSA Administrator on Politics and Flight Bans

TSA Administrator on Politics and Flight Bans

AP (July 24, 2014) TSA administrator, John Pistole's took part in the Aspen Security Forum 2014, where he answered questions on lifting of the ban on flights into Israel's Tel Aviv airport and whether politics played a role in lifting the ban. (July 24) Video provided by AP
Powered by NewsLook.com
Creative Makeovers for Ugly Cellphone Towers

Creative Makeovers for Ugly Cellphone Towers

AP (July 24, 2014) Mobile phone companies and communities across the country are going to new lengths to disguise those unsightly cellphone towers. From a church bell tower to a flagpole, even a pencil, some towers are trying to make a point. (July 24) Video provided by AP
Powered by NewsLook.com
Algonquin Power Goes Activist on Its Target Gas Natural

Algonquin Power Goes Activist on Its Target Gas Natural

TheStreet (July 23, 2014) When The Deal's Amanda Levin exclusively reported that Gas Natural had been talking to potential suitors, the Ohio company responded with a flat denial, claiming its board had not talked to anyone about a possible sale. Lo and behold, Canadian utility Algonquin Power and Utilities not only had approached the company, but it did it three times. Its last offer was for $13 per share as Gas Natural's was trading at a 60-day moving average of about $12.50 per share. Now Algonquin, which has a 4.9% stake in Gas Natural, has taken its case to shareholders, calling on them to back its proposals or, possibly, a change in the target's board. Video provided by TheStreet
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:

Breaking News:
from the past week

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile: iPhone Android Web
Follow: Facebook Twitter Google+
Subscribe: RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins