Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Duke researchers report technique to make more-uniform ’buckytubes’

29.10.2002


Duke University chemists report they have made a significant advance toward producing tiny hollow tubes of carbon atoms, called "nanotubes," with electronic properties reliable enough to use in molecular-sized circuits.

In a report posted Oct. 28, 2002, in the online version of the Journal of the American Chemical Society, the Duke group described a method to synthesize starting catalytic "nanocluster" particles of identical size that, in turn, can foster the growth of carbon nanotubes that vary in size far less than those produced previously.

"This is really a first step toward a big future," said Jie Liu, a Duke associate professor of chemistry and the group’s leader, of the unprecedented nanotube uniformity they achieved using this process.



Sometimes called "buckytubes," carbon nanotubes’ properties were first studied by Japanese researchers in the early 1990s. The nanotubes, measuring just billionths of a meter in diameter (nano means "billionths"), were found to be lightweight but exceptionally strong, with unusual electronic properties.

Depending upon their atomic arrangements, nanotubes can act like conducting metals or like semiconductors, Liu said.

Since microelectronic devices such as computer chips use both semiconductors and metals, researchers foresee nanotubes as the building blocks for even smaller electronic circuitry than the millionths-of-a-meter scale resolutions of today’s microchips.

However, "controlling the electronic properties of the nanotubes is becoming the biggest bottleneck that limits the development of nanotube research," Liu said in an interview.

The control problem arises because those electronic properties vary with the way nanotubes’ atoms are arranged. And how their atoms are arranged is directly tied to the nanotubes’ diameters -- which, until the fabrication advance by Liu and his colleagues, could vary considerably.

In their journal report, Liu’s graduate student Lei An, Liu and two University of North Carolina at Chapel Hill researchers describe a technique for growing nanotubes with diameters that varied by about 17 percent.

Using a technique called chemical vapor deposition, An and Liu sprouted the nanotubes from tiny catalyst particles called "nanoclusters." The researchers were able to make each of the nanoclusters completely identical.

"We have shown quite convincingly that by controlling the size of the starting catalyst we can control the diameter of the nanotubes," Liu said. "This is the first time that an identical catalyst has been used.

"The ultimate goal of the research is to produce multiple identical nanotubes using the same kind of catalyst particle," said Liu. "We’re still pretty far from there. But it really represents a step forward to show that we have a collection of identical catalyst particles to start with."

The specific nanocluster made in An and Liu’s Duke laboratory is one of a large family of catalytic molecules based on molybdenum oxide, he said.

Their nanoclusters contain 30 iron and 84 molybdenum atoms, plus carbon, hydrogen and oxygen atoms. While such clusters are not available from chemical supply houses, they are quite easy to make, Liu said. "And because it’s so easy to make these clusters, it should also be easy to scale up to make large amounts of catalyst and large amounts of nanotubes," he said.

The researchers credited the use of a growth-regulating chemical called 3-aminopropyltriethoxysilane (APTES) for achieving more-uniform nanotubes diameters. The APTES kept the nanocluster particles confined to separate islands of discrete size as the nanotubes budded from a silicon dioxide surface.

If researchers can precisely control the nanotubes’ diameters, said Liu, the researchers hope in the near future to make pure semiconducting and pure metallic nanotubes. "All the samples we are able to make now are a mix of metallic and semiconducting tubes," he said.

Carbon nanotubes are sometimes called buckytubes because of their structural similarities to carbon-based polyhedral molecules called buckminsterfullerenes, or "buckyballs." Pioneering work with buckyballs won a Nobel Prize for Richard Smalley’s research group at Rice University, where Liu did postdoctoral work before coming to Duke.

The problems controlling nanotubes’ electronic properties were recently noted in a news feature in the Oct. 10, 2002, issue of the journal Nature. "These difficulties may not be insurmountable," that article said, "but they have persuaded some scientists to turn their attention elsewehere."

In 2001, IBM researchers announced a "constructive destruction" method for separating semiconducting from metallic nanotubes by destroying the metallic ones with bursts of electricity.

An IBM news release said that other researchers have found semiconducting carbon nanotubes should be able to perform as well as silicon when configured into transistors. But nanotubes’ molecular-scale sizes could result in computers that are smaller and operate faster using less power than today’s silicon-based technology.

Monte Basgall | EurekAlert!
Further information:
http://www.duke.edu/

More articles from Life Sciences:

nachricht Chains of nanogold – forged with atomic precision
23.09.2016 | Suomen Akatemia (Academy of Finland)

nachricht Self-assembled nanostructures hit their target
23.09.2016 | King Abdullah University of Science and Technology

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: OLED microdisplays in data glasses for improved human-machine interaction

The Fraunhofer Institute for Organic Electronics, Electron Beam and Plasma Technology FEP has been developing various applications for OLED microdisplays based on organic semiconductors. By integrating the capabilities of an image sensor directly into the microdisplay, eye movements can be recorded by the smart glasses and utilized for guidance and control functions, as one example. The new design will be debuted at Augmented World Expo Europe (AWE) in Berlin at Booth B25, October 18th – 19th.

“Augmented-reality” and “wearables” have become terms we encounter almost daily. Both can make daily life a little simpler and provide valuable assistance for...

Im Focus: Artificial Intelligence Helps in the Discovery of New Materials

With the help of artificial intelligence, chemists from the University of Basel in Switzerland have computed the characteristics of about two million crystals made up of four chemical elements. The researchers were able to identify 90 previously unknown thermodynamically stable crystals that can be regarded as new materials. They report on their findings in the scientific journal Physical Review Letters.

Elpasolite is a glassy, transparent, shiny and soft mineral with a cubic crystal structure. First discovered in El Paso County (Colorado, USA), it can also be...

Im Focus: Complex hardmetal tools out of the 3D printer

For the first time, Fraunhofer IKTS shows additively manufactured hardmetal tools at WorldPM 2016 in Hamburg. Mechanical, chemical as well as a high heat resistance and extreme hardness are required from tools that are used in mechanical and automotive engineering or in plastics and building materials industry. Researchers at the Fraunhofer Institute for Ceramic Technologies and Systems IKTS in Dresden managed the production of complex hardmetal tools via 3D printing in a quality that are in no way inferior to conventionally produced high-performance tools.

Fraunhofer IKTS counts decades of proven expertise in the development of hardmetals. To date, reliable cutting, drilling, pressing and stamping tools made of...

Im Focus: Launch of New Industry Working Group for Process Control in Laser Material Processing

At AKL’16, the International Laser Technology Congress held in May this year, interest in the topic of process control was greater than expected. Appropriately, the event was also used to launch the Industry Working Group for Process Control in Laser Material Processing. The group provides a forum for representatives from industry and research to initiate pre-competitive projects and discuss issues such as standards, potential cost savings and feasibility.

In the age of industry 4.0, laser technology is firmly established within manufacturing. A wide variety of laser techniques – from USP ablation and additive...

Im Focus: New laser joining technologies at ‘K 2016’ trade fair

Every three years, the plastics industry gathers at K, the international trade fair for plastics and rubber in Düsseldorf. The Fraunhofer Institute for Laser Technology ILT will also be attending again and presenting many innovative technologies, such as for joining plastics and metals using ultrashort pulse lasers. From October 19 to 26, you can find the Fraunhofer ILT at the joint Fraunhofer booth SC01 in Hall 7.

K is the world’s largest trade fair for the plastics and rubber industry. As in previous years, the organizers are expecting 3,000 exhibitors and more than...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Experts from industry and academia discuss the future mobile telecommunications standard 5G

23.09.2016 | Event News

ICPE in Graz for the seventh time

20.09.2016 | Event News

Using mathematical models to understand our brain

16.09.2016 | Event News

 
Latest News

Chains of nanogold – forged with atomic precision

23.09.2016 | Life Sciences

New leukemia treatment offers hope

23.09.2016 | Health and Medicine

Self-assembled nanostructures hit their target

23.09.2016 | Life Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>