Featured Research

from universities, journals, and other organizations

Controlling heat flow with atomic-level precision

Date:
April 22, 2012
Source:
University of Illinois at Urbana-Champaign
Summary:
Through a combination of atomic-scale materials design and ultrafast measurements, researchers have revealed new insights about how heat flows across an interface between two materials. The researchers demonstrated that a single layer of atoms can disrupt or enhance heat flow across an interface, a finding with implications for future technologies and for materials research.

Through atomic-scale manipulation, researchers at the University of Illinois have demonstrated that a single layer of atoms can disrupt or enhance heat flow across an interface.
Credit: Mark Losego

Through a combination of atomic-scale materials design and ultrafast measurements, researchers at the University of Illinois have revealed new insights about how heat flows across an interface between two materials.

The researchers demonstrated that a single layer of atoms can disrupt or enhance heat flow across an interface. Their results are published this week in Nature Materials.

Improved control of heat exchange is a key element to enhancing the performance of current technologies such as integrated circuits and combustion engines as well as emerging technologies such as thermoelectric devices, which harvest renewable energy from waste heat. However, achieving control is hampered by an incomplete understanding of how heat is conducted through and between materials.

"Heat travels through electrically insulating material via 'phonons,' which are collective vibrations of atoms that travel like waves through a material," said David Cahill, a Willett Professor and the head of materials science and engineering at Illinois and co-author of the paper. "Compared to our knowledge of how electricity and light travel through materials, scientists' knowledge of heat flow is rather rudimentary."

One reason such knowledge remains elusive is the difficulty of accurately measuring temperatures, especially at small-length scales and over short time periods -- the parameters that many micro and nano devices operate under.

Over the past decade, Cahill's group has refined a measurement technique using very short laser pulses, lasting only one trillionth of a second, to probe heat flow accurately with nanometer-depth resolution. Cahill teamed up with Paul Braun, the Racheff Professor of Materials Science and Engineering at the U. of I. and a leader in nanoscale materials synthesis, to apply the technique to understanding how atomic-scale features affect heat transport.

"These experiments used a 'molecular sandwich' that allowed us to manipulate and study the effect that chemistry at the interface has on heat flow, at an atomic scale," Braun said.

The researchers assembled their molecular sandwich by first depositing a single layer of molecules on a quartz surface. Next, through a technique known as transfer-printing, they placed a very thin gold film on top of these molecules. Then they applied a heat pulse to the gold layer and measured how it traveled through the sandwich to the quartz at the bottom.

By adjusting just the composition of the molecules in contact with the gold layer, the group observed a change in heat transfer depending on how strongly the molecule bonded to the gold. They demonstrated that stronger bonding produced a twofold increase in heat flow.

"This variation in heat flow could be much greater in other systems," said Mark Losego, who led this research effort as a postdoctoral scholar at Illinois and is now a research professor at North Carolina State University. "If the vibrational modes for the two solids were more similar, we could expect changes of up to a factor of 10 or more."

The researchers also used their ability to systematically adjust the interfacial chemistry to dial-in a heat flow value between the two extremes, verifying the ability to use this knowledge to design materials systems with desired thermal transport properties.

"We've basically shown that changing even a single layer of atoms at the interface between two materials significantly impacts heat flow across that interface," said Losego.

Scientifically, this work opens up new avenues of research. The Illinois group is already working toward a deeper fundamental understanding of heat transfer by refining measurement methods for quantifying interfacial bonding stiffness, as well as investigating temperature dependence, which will reveal a better fundamental picture of how the changes in interface chemistry are disrupting or enhancing the flow of heat across the interface.

"For many years, the physical models for heat flow between two materials have ignored the atomic-level features of an interface," Cahill said. "Now these theories need to be refined. The experimental methods developed here will help quantify the extent to which interfacial structural features contribute to heat flow and will be used to validate these new theories."

Braun and Cahill are affiliated with the Frederick Seitz Materials Research Laboratory at the U. of I. Braun is also affiliated with the department of chemistry and the Beckman Institute for Advanced Science and Technology. The Air Force Office of Scientific Research supported this work.


Story Source:

The above story is based on materials provided by University of Illinois at Urbana-Champaign. Note: Materials may be edited for content and length.


Journal Reference:

  1. Mark D. Losego, Martha E. Grady, Nancy R. Sottos, David G. Cahill, Paul V. Braun. Effects of chemical bonding on heat transport across interfaces. Nature Materials, 2012; DOI: 10.1038/nmat3303

Cite This Page:

University of Illinois at Urbana-Champaign. "Controlling heat flow with atomic-level precision." ScienceDaily. ScienceDaily, 22 April 2012. <www.sciencedaily.com/releases/2012/04/120422134955.htm>.
University of Illinois at Urbana-Champaign. (2012, April 22). Controlling heat flow with atomic-level precision. ScienceDaily. Retrieved September 23, 2014 from www.sciencedaily.com/releases/2012/04/120422134955.htm
University of Illinois at Urbana-Champaign. "Controlling heat flow with atomic-level precision." ScienceDaily. www.sciencedaily.com/releases/2012/04/120422134955.htm (accessed September 23, 2014).

Share This



More Matter & Energy News

Tuesday, September 23, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Company Copies Keys From Photos

Company Copies Keys From Photos

Newsy (Sep. 22, 2014) A new company allows customers to make copies of keys by simply uploading a couple of photos. But could it also be great for thieves? Video provided by Newsy
Powered by NewsLook.com
Rockefeller Oil Heirs Switching To Clean Energy

Rockefeller Oil Heirs Switching To Clean Energy

Newsy (Sep. 22, 2014) The Rockefellers — heirs to an oil fortune that made the family name a symbol of American wealth — are switching from fossil fuels to clean energy. Video provided by Newsy
Powered by NewsLook.com
Raw: SpaceX Rocket Carries 3-D Printer to Space

Raw: SpaceX Rocket Carries 3-D Printer to Space

AP (Sep. 22, 2014) A SpaceX Rocket launched from Cape Canaveral, carrying a custom-built 3-D printer into space. NASA envisions astronauts one day using the printer to make their own spare parts. (Sept. 22) Video provided by AP
Powered by NewsLook.com
Inside London's Massive Sewer Tunnel Project

Inside London's Massive Sewer Tunnel Project

AP (Sep. 22, 2014) Billions of dollars are being spent on a massive super sewer to take away London's vast output of waste, which is endangering the River Thames. (Sept. 22) Video provided by AP
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:

Breaking News:

Strange & Offbeat Stories


Space & Time

Matter & Energy

Computers & Math

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile: iPhone Android Web
Follow: Facebook Twitter Google+
Subscribe: RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins