Major nanotechnology hurdle not so worrisome, thanks to Indiana University chemistry discovery

December 02, 2003

BLOOMINGTON, Ind. -- According to the classic rules of physics, substances melt at a lower temperature when their sizes decrease. But scientists at Indiana University Bloomington have found that at least one substance, gallium, breaks the rules, remaining stable as a solid at temperatures as much as 400 degrees Fahrenheit above the element's normal melting point. Their report will be published in an upcoming issue of Physical Review Letters.

The discovery gives hope to some nanotechnologists and "nanocomputer" engineers, who have been worried that components will behave unpredictably at small sizes, possibly even melting at room temperature.

"We expect this finding will interest nanotechnologists and the manufacturers of tomorrow's computers," said chemist Martin Jarrold, who led the National Science Foundation-funded research. "But we also believe chemists will find this phenomenon exciting -- it totally confounds their expectations."

Jarrold and his collaborators showed that clusters of a few gallium atoms remain solid -- like an impossible house of cards with key supports removed -- rather than becoming liquid near the element's normal melting point, 86 F. Just as surprisingly, the researchers showed that the tiny gallium clusters are actually more stable as solids when composed of 17, 39, and 40 atoms than in the form of a gallium slab containing trillions of atoms.

Jarrold decided to test the stability of a substance that is especially sensitive to temperature changes near room temperature. Fitting that description is the metallic element gallium, which has an unusually low melting point. Placing a warm fingertip on a cube of gallium will cause it to melt.

The researchers constructed a special device to shoot tiny gallium particles containing just a few atoms into gaseous helium. Collisions with the helium atoms broke the gallium clusters into small pieces. Two mass spectrometers measured the size of the intact and broken gallium clusters. By measuring the energy needed to break the clusters into pieces, the researchers were able to determine whether the clusters were in liquid or solid states. Jarrold and his team observed that gallium clusters with 39 and 40 atoms melt at around 531 F. Gallium clusters containing 17 atoms didn't melt at all across the -297 to 837 F temperature range the scientists surveyed. Why the gallium clusters retained such stability at high temperature is a mystery.

Not all elements or compounds are likely to behave as gallium does. Using the same method, Jarrold previously learned that sodium chloride (table salt) particles obey the classical rules of physics. Small salt particles with just a few atoms melt at low temperatures.

Despite its potential implications for industry, Jarrold said his discovery and his general interest in atomic and molecular clusters, which began at Bell Laboratories, are mainly academic.

"I just think it's fascinating to ask how small you can make something before its properties change," Jarrold said.

IUB chemists Gary A. Breaux and Robert C. Benirschke, Nagoya University (Japan) chemist Toshiki Sugai, and Intel Corporation scientist Brian Kinnear also contributed to the report, which was funded by the National Science Foundation. All of the report's contributing authors were at IUB when the study was completed.
To speak with Jarrold, contact David Bricker at 812-856-9035 or

Indiana University

Related Physics Articles from Brightsurf:

Helium, a little atom for big physics
Helium is the simplest multi-body atom. Its energy levels can be calculated with extremely high precision only relying on a few fundamental physical constants and the quantum electrodynamics (QED) theory.

Hyperbolic metamaterials exhibit 2T physics
According to Igor Smolyaninov of the University of Maryland, ''One of the more unusual applications of metamaterials was a theoretical proposal to construct a physical system that would exhibit two-time physics behavior on small scales.''

Challenges and opportunities for women in physics
Women in the United States hold fewer than 25% of bachelor's degrees, 20% of doctoral degrees and 19% of faculty positions in physics.

Indeterminist physics for an open world
Classical physics is characterized by the equations describing the world.

Leptons help in tracking new physics
Electrons with 'colleagues' -- other leptons - are one of many products of collisions observed in the LHCb experiment at the Large Hadron Collider.

Has physics ever been deterministic?
Researchers from the Austrian Academy of Sciences, the University of Vienna and the University of Geneva, have proposed a new interpretation of classical physics without real numbers.

Twisted physics
A new study in the journal Nature shows that superconductivity in bilayer graphene can be turned on or off with a small voltage change, increasing its usefulness for electronic devices.

Physics vs. asthma
A research team from the MIPT Center for Molecular Mechanisms of Aging and Age-Related Diseases has collaborated with colleagues from the U.S., Canada, France, and Germany to determine the spatial structure of the CysLT1 receptor.

2D topological physics from shaking a 1D wire
Published in Physical Review X, this new study propose a realistic scheme to observe a 'cold-atomic quantum Hall effect.'

Helping physics teachers who don't know physics
A shortage of high school physics teachers has led to teachers with little-to-no training taking over physics classrooms, reports show.

Read More: Physics News and Physics 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