UA Physicists Find Key to Long-Lived Metal Nanowires

Aug 25, 2005
UA Physicists Find Key to Long-Lived Metal Nanowires

University of Arizona physicists have discovered what it takes to make metal 'nanowires' that last a long time. This is particularly important to the electronics industry, which hopes to use tiny wires -- that have diameters counted in tens of atoms -- in Lilputian electronic devices in the next 10 to 15 years.

This illustration represents a metallic quantum wire before it's stretched to the breaking point. (Illustration: Courtesy of Charles Stafford)

Researchers predict that such nanotechnology will be the next Big Thing to revolutionize the computing, medical, power and other industries in coming decades.

Although researchers in Japan, the Netherlands, Spain, Brazil and the United States have had some success at making nanowires -- extremely small filaments that transport electrons -- the wires don't last long except at low temperatures.

What researchers need are robust nanowires that will take repeated use without failing at room temperature and higher.

UA post-doctoral associate Jerome Buerki and physics Professors Charles Stafford and Daniel Stein developed a theory that explains why nanowires thin away to nothing at non-zero temperatures. Energy fluctuations in a nanowire at higher temperatures create a collective motion, or "soliton," among atoms in the wire. As each of these kink-like structures propagates from one end of the wire to the other, the wire thins.

Stafford has posted movies that show this phenomenon on his Web page, www.physics.arizona.edu/~stafford/necking.htmlThe movie was made by the Takayanagi group at the Tokyo Institute of Technology.

"Our theory makes one very simple prediction, which is that the energy barrier that creates these kinks depends, very simply, on the square root of the surface tension of the wire," Stafford said. "That's quite counterintuitive, because naively you'd think that surface tension should actually make the filament unstable. But the larger the surface tension, the more stable the wire, regardless of the radius of the wire."

Creation of solitons, or kinks, in the wire depends on two competing forces - the surface tension and a quantum force that holds the wire together, Stafford explained. "It just so happens that the competition between those two forces leads to a kind of universal energy barrier which goes as the square root of the surface tension."

The discovery explains why experimentalists have had more luck at making longer-lived nanowires using such noble metals as gold and silver rather than sodium or other alkali metals. According to the UA physicists' theory, copper is the best metal for making nanowires because it has the largest natural surface tension of the nanowire metals.

"The hardest thing with developing nanowires, I think, is how to fabricate them in a controlled way," Stafford said. "The movies show how researchers can fabricate one tiny wire, but that's not connecting many such wires, or connecting them to make a circuit.

"But at least, our work says that these wires are very stable, and that we understand exactly how stable they are. I think that can give people confidence to move ahead with trying to do something practical with them."

The research, funded by the National Science Foundation, will be published this week in Physical Review Letters. The article, "Theory of Metastability in Simple Metal Nanowires,"appears online at link.aps.org/abstract/PRL/v95/390601 .

Source: University of Arizona

Explore further: New nanodevice defeats drug resistance

add to favorites email to friend print save as pdf

Related Stories

Extra-short nanowires best for brain

Jan 15, 2015

If in the future electrodes are inserted into the human brain - either for research purposes or to treat diseases - it may be appropriate to give them a 'coat' of nanowires that could make them less irritating for the brain ...

Uniform nanowire arrays for science and manufacturing

Dec 03, 2014

Defect-free nanowires with diameters in the range of 100 nanometers (nm) hold significant promise for numerous in-demand applications including printable transistors for flexible electronics, high-efficiency ...

Team grows uniform nanowires

Nov 10, 2014

A researcher from Missouri University of Science and Technology has developed a new way to grow nanowire arrays with a determined diameter, length and uniform consistency. This approach to growing nanomaterials ...

Recommended for you

Electrons moving along defined snake states

51 minutes ago

Physicists at the University of Basel have shown for the first time that electrons in graphene can be moved along a predefined path. This movement occurs entirely without loss and could provide a basis for ...

New nanodevice defeats drug resistance

18 hours ago

Chemotherapy often shrinks tumors at first, but as cancer cells become resistant to drug treatment, tumors can grow back. A new nanodevice developed by MIT researchers can help overcome that by first blocking ...

Glass coating improves battery performance

18 hours ago

Lithium-sulfur batteries have been a hot topic in battery research because of their ability to produce up to 10 times more energy than conventional batteries, which means they hold great promise for applications ...

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.