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 Toward a 'smart' patch that automatically delivers insulin when needed
18.01.2017 | American Chemical Society

nachricht 127 at one blow...
18.01.2017 | Stiftung Zoologisches Forschungsmuseum Alexander Koenig, Leibniz-Institut für Biodiversität der Tiere

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: How gut bacteria can make us ill

HZI researchers decipher infection mechanisms of Yersinia and immune responses of the host

Yersiniae cause severe intestinal infections. Studies using Yersinia pseudotuberculosis as a model organism aim to elucidate the infection mechanisms of these...

Im Focus: Interfacial Superconductivity: Magnetic and superconducting order revealed simultaneously

Researchers from the University of Hamburg in Germany, in collaboration with colleagues from the University of Aarhus in Denmark, have synthesized a new superconducting material by growing a few layers of an antiferromagnetic transition-metal chalcogenide on a bismuth-based topological insulator, both being non-superconducting materials.

While superconductivity and magnetism are generally believed to be mutually exclusive, surprisingly, in this new material, superconducting correlations...

Im Focus: Studying fundamental particles in materials

Laser-driving of semimetals allows creating novel quasiparticle states within condensed matter systems and switching between different states on ultrafast time scales

Studying properties of fundamental particles in condensed matter systems is a promising approach to quantum field theory. Quasiparticles offer the opportunity...

Im Focus: Designing Architecture with Solar Building Envelopes

Among the general public, solar thermal energy is currently associated with dark blue, rectangular collectors on building roofs. Technologies are needed for aesthetically high quality architecture which offer the architect more room for manoeuvre when it comes to low- and plus-energy buildings. With the “ArKol” project, researchers at Fraunhofer ISE together with partners are currently developing two façade collectors for solar thermal energy generation, which permit a high degree of design flexibility: a strip collector for opaque façade sections and a solar thermal blind for transparent sections. The current state of the two developments will be presented at the BAU 2017 trade fair.

As part of the “ArKol – development of architecturally highly integrated façade collectors with heat pipes” project, Fraunhofer ISE together with its partners...

Im Focus: How to inflate a hardened concrete shell with a weight of 80 t

At TU Wien, an alternative for resource intensive formwork for the construction of concrete domes was developed. It is now used in a test dome for the Austrian Federal Railways Infrastructure (ÖBB Infrastruktur).

Concrete shells are efficient structures, but not very resource efficient. The formwork for the construction of concrete domes alone requires a high amount of...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

12V, 48V, high-voltage – trends in E/E automotive architecture

10.01.2017 | Event News

2nd Conference on Non-Textual Information on 10 and 11 May 2017 in Hannover

09.01.2017 | Event News

Nothing will happen without batteries making it happen!

05.01.2017 | Event News

 
Latest News

A big nano boost for solar cells

18.01.2017 | Power and Electrical Engineering

Glass's off-kilter harmonies

18.01.2017 | Materials Sciences

Toward a 'smart' patch that automatically delivers insulin when needed

18.01.2017 | Life Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>