Subscribe to our free daily newsletters
. 24/7 Space News .




Subscribe to our free daily newsletters



TECH SPACE
Caution: Shrinks when warm
by Staff Writers
Storrs CT (SPX) Oct 09, 2015


Sahan Handunkanda, a graduate student in physics and first author on the paper published by the American Physical Society, holds up a crystal of scandium trifluoride. Image courtesy Peter Morenus and UConn.

Most materials swell when they warm, and shrink when they cool. But UConn physicist Jason Hancock has been investigating a substance that responds in reverse: it shrinks when it warms. Although thermal expansion, and the cracking and warping that often result, are an everyday occurrence - in buildings, bridges, electronics, and almost anything else exposed to wide temperature swings - physicists have trouble explaining why solids behave that way.

Research by Hancock and his colleagues into scandium trifluoride, a material that has negative thermal expansion, published 1 October in Physical Review B, may lead to a better understanding of why materials change volume with temperature at all, with potential applications such as more durable electronics.

The classical way to think about solids like glass, metal, and rock imagines them made of atoms hooked together by springs. The springs stretch and flex in response to heat. But because each spring, when it expands, puts pressure on its neighboring springs - and all those neighboring springs expand the same amount and exert the same pressure on the first spring and all their own neighboring springs - the forces they exert on each other should be symmetrical, and the material should neither expand nor contract.

"In many ways, the model is good," says Hancock. "It explains inelastic scattering of neutrons and x-rays, lots of other optical effects, the speed of sound waves, aspects of elasticity and heat conduction, even the transition temperature of some superconductors." But it doesn't do a good job of explaining thermal expansion.

Hancock and graduate student Sahan Handunkanda decided to look at scandium trifluoride because its odd behavior might give them some clues on what to look for in more typical materials. Not only does scandium trifluoride drastically shrink as it warms over a huge range of temperature (almost 1,100K or 2,000 F); it also keeps the same, stable cubic crystal structure over an even larger temperature range, from near absolute zero to 1,800 degrees Kelvin (2,780 degrees Fahrenheit), at which point it melts.

Very few materials can boast of being so stable; most have some kind of phase change, during which their atoms shift positions, at least once when they're warmed over 2,780 degrees Fahrenheit.

To figure out what was happening inside scandium trifluoride, the researchers decided to use x-rays to show how the atoms in the crystal moved at very low temperatures, close to absolute zero. To do this right, they needed a perfect crystal of scandium trifluoride, something that was very difficult to get.

After searching, they found possibly the only source for the perfect crystals they needed: a group at Kirensky Institute of Physics in Krasnoyarsk, Siberia, led by Vladimir Voronov. Voronov agreed to send them crystals by mail, and they scheduled x-ray beam time at the Advanced Photon Source at Argonne National Laboratory.

The researchers shone a beam of x-rays onto the perfect crystal. They knew exactly how much energy the x-rays had going in to the crystal, and they carefully tracked how much energy the x-rays had coming out. By tracking the amount of energy the x-rays lost, the angle they entered the crystal, and the angle they emerged, the researchers could calculate how the scandium trifluoride atoms moved.

"When x-rays bounce from the sample, they make little splashes of vibration in the lattice," Hancock says. Columns of scandium trifluoride molecules, each shaped like a little octahedron, seemed to be rotating in place, even at close to zero degrees.

The ease with which the columns twisted at close to zero temperature is unusual - the structure is 'softer' than most materials at zero Kelvin. The observed softness of scandium fluoride's molecular structure suggests it's about to undergo a phase shift, but it never quite gets there, even near absolute zero. Such a shift near absolute zero is called a quantum phase transition, and is an area of intense research activity in physics, mainly because such transitions often challenge current theoretical understanding of how materials work.

The clues uncovered in this study suggest that there could be a deep relationship between quantum forces and the giant shrinkage the material experiences as it warms. Hancock and Handunkanda would like to explore the implications of that both experimentally and theoretically.

On a more immediate level, scandium trifluoride is a material with a future. Its crystal structure is similar to many materials used in electronics, and it's transparent, making it an interesting potential component of devices that don't shrink, crack, or break under thermal stress.


Thanks for being here;
We need your help. The SpaceDaily news network continues to grow but revenues have never been harder to maintain.

With the rise of Ad Blockers, and Facebook - our traditional revenue sources via quality network advertising continues to decline. And unlike so many other news sites, we don't have a paywall - with those annoying usernames and passwords.

Our news coverage takes time and effort to publish 365 days a year.

If you find our news sites informative and useful then please consider becoming a regular supporter or for now make a one off contribution.

SpaceDaily Contributor
$5 Billed Once


credit card or paypal
SpaceDaily Monthly Supporter
$5 Billed Monthly


paypal only

.


Related Links
University of Connecticut
Space Technology News - Applications and Research






Comment on this article via your Facebook, Yahoo, AOL, Hotmail login.

Share this article via these popular social media networks
del.icio.usdel.icio.us DiggDigg RedditReddit GoogleGoogle

Previous Report
TECH SPACE
Purdue professor solves 140-year fluid mechanics enigma
West Lafayette IN (SPX) Oct 08, 2015
A Purdue University researcher has solved a 140-year-old enigma in fluid mechanics: Why does a simple formula describe the seemingly complex physics for the behavior of elliptical particles moving through fluid? The findings have potential implications for research and industry because ellipsoid nanoparticles are encountered in various applications including those involving pharmaceuticals ... read more


TECH SPACE
Lunar Pox

Space startup confirms plans for robotic moon landings

Asteroids found to be the moon's main 'water supply'

Russian scientist hope to get rocket fuel, water, oxygen from Lunar ice

TECH SPACE
MRO imagery reveals Red Planet's stressed substrate

Geology Award Going to Mars Landing Site Expert at JPL

Terraforming the Red Planet: Nuclear Blasts Could Warm Mars for Humans?

NASA Lays the Groundwork for Homesteading in Space

TECH SPACE
Selected NASA Discovery Missions Include Three With PSI Ties

NASA Selects Investigations for Future Key Planetary Mission

Chinese herbal expert among Nobel medicine prize winners

Down to Earth and walking the line

TECH SPACE
Exhibition on "father of Chinese rocketry" opens in U.S.

The First Meeting of the U.S.-China Space Dialogue

China's new carrier rocket succeeds in 1st trip

China launches new type of carrier rocket: state media

TECH SPACE
Meet the International Docking Adapter

NASA extends Boeing contract for International Space Station

Russian launches cargo spaceship to the ISS

Successful re-entry of H-II Transfer Vehicle Kounotori5

TECH SPACE
Arianespace signs ARSAT to launch a new satellite for Argentina

Ariane 5 orbits Sky Muster and ARSAT-2

A satellite launcher for the Middle East

45th Space Wing supports ULA's 100th launch

TECH SPACE
The Most Stable Source of Light in the World

Earth-class planets likely have protective magnetic fields, aiding life

Stellar atmosphere can be used to predict the composition of rocky exoplanets

Watching an exoplanet in motion around a distant star

TECH SPACE
Caution: Shrinks when warm

Flipping molecular attachments amps up activity of CO2 catalyst

New system allows heightened purity of a metal binding compound

Redefining temperature with precision lasers




Memory Foam Mattress Review
Newsletters :: SpaceDaily :: SpaceWar :: TerraDaily :: Energy Daily
XML Feeds :: Space News :: Earth News :: War News :: Solar Energy News






The content herein, unless otherwise known to be public domain, are Copyright 1995-2017 - Space Media Network. All websites are published in Australia and are solely subject to Australian law and governed by Fair Use principals for news reporting and research purposes. AFP, UPI and IANS news wire stories are copyright Agence France-Presse, United Press International and Indo-Asia News Service. ESA news reports are copyright European Space Agency. All NASA sourced material is public domain. Additional copyrights may apply in whole or part to other bona fide parties. All articles labeled "by Staff Writers" include reports supplied to Space Media Network by industry news wires, PR agencies, corporate press officers and the like. Such articles are individually curated and edited by Space Media Network staff on the basis of the report's information value to our industry and professional readership. Advertising does not imply endorsement, agreement or approval of any opinions, statements or information provided by Space Media Network on any Web page published or hosted by Space Media Network. Privacy Statement