Nanotechnology Now

Our NanoNews Digest Sponsors

Heifer International

Wikipedia Affiliate Button


DHgate

Home > Press > Structural Distortions Emerge From Nothing At The Nanoscale

As the emergent-dipole material (right) is warmed, fluctuating local dipoles appear from an undisturbed ground state (i.e., from “nothing”). This is in contrast to the conventional material (left), which has aligned dipoles at low temperatures. The flip-flopping displacements impede the movement of heat through the material, allowing a strong temperature gradient to be maintained. Heat on one side of the material can then induce a flow of electrons from the hot to the cooler side. Capturing this current could put waste heat to work. (View the animation here engineering.columbia.edu/billinge-team-makes-discovery-thermoelectrics)
As the emergent-dipole material (right) is warmed, fluctuating local dipoles appear from an undisturbed ground state (i.e., from “nothing”). This is in contrast to the conventional material (left), which has aligned dipoles at low temperatures. The flip-flopping displacements impede the movement of heat through the material, allowing a strong temperature gradient to be maintained. Heat on one side of the material can then induce a flow of electrons from the hot to the cooler side. Capturing this current could put waste heat to work. (View the animation here engineering.columbia.edu/billinge-team-makes-discovery-thermoelectrics)

Abstract:
Newly Discovered Phase Helps Explain Materials' Ability to Convert Waste Heat to Electricity

Structural Distortions Emerge From Nothing At The Nanoscale

Upton, NY | Posted on December 16th, 2010

Scientists have discovered that a class of materials known to convert heat to electricity and vice versa behaves quite unexpectedly at the nanoscale in response to changes in temperature. The discovery — described in the December 17, 2010, issue of Science — is a new "opposite-direction" phase transition that helps explain the strong thermoelectric response of these materials. It may also help scientists identify other useful thermoelectrics, and could further their application in capturing energy lost as heat, for example, in automotive and factory exhaust.

The scientists — from Columbia University's School of Engineering and Applied Science, the U.S. Department of Energy's (DOE) Brookhaven National Laboratory, Argonne National Laboratory, Los Alamos National Laboratory, Northwestern University, and the Swiss Federal Institute of Technology — were studying lead chalcogenides (lead paired with tellurium, selenium, or sulfur) using newly available experimental techniques and theoretical approaches that allow them to "see" and model behavior of individual atoms at the nanoscale, or on the order of billionths of a meter. With those tools they were able to observe subtle changes in atomic arrangements invisible to conventional probes of structure.

To understand the phase transition the scientists observed, think of the everyday response of a gas like steam cooling to form liquid water, and then freezing to form solid ice. In each case, the atoms undergo some form of structural rearrangement, explains Simon Billinge, a physicist at Columbia Engineering and Brookhaven Lab and a lead author on the Science paper.

"Sometimes, further cooling will lead to further structural transitions: Atoms in the crystal rearrange or become displaced to lower the overall symmetry," Billinge says. The development of such localized atomic distortions upon cooling is normal, he says. "What we discovered in lead chalcogenides is the opposite behavior: At the very lowest temperature, there were no atomic displacements, nothing — but on warming, displacements appear!"

The techniques the scientists used to observe this nanoscale atomic action were high-tech versions of x-ray vision, aided by mathematical and computer analysis of the results. First the lead materials were made in a purified powder form at Northwestern University. Then the scientists bombarded the samples with two kinds of beams — x-rays at the Advanced Photon Source at Argonne and neutrons at the Lujan Neutron Scattering Center at Los Alamos. Detectors gather information about how these beams scatter off the sample to produce diffraction patterns that indicate positions and arrangements of the atoms. Further mathematical and computational analysis of the data using computer programs developed at Brookhaven and Columbia allowed the scientists to model and interpret what was happening at the atomic level over a range of temperatures.

Brookhaven physicist Emil Bozin, first author on the paper, was the first to notice the odd behavior in the data, and he worked tenaciously to prove it was something new and not a data artifact. "If we had just looked at the average structure, we never would have observed this effect. Our analysis of atomic pair distribution functions gives us a much more local view — the distance from one particular atom to its nearest neighbors — rather than just the average," Bozin says. The detailed analysis revealed that, as the material got warmer, these distances were changing on a tiny scale — about 0.025 nanometers — indicating that individual atoms were becoming displaced.

The scientists have made an animation to illustrate the emergence of these displacements upon heating. In it, the displacements are represented by arrows to indicate the changing orientations of the atoms as they flip back and forth, or fluctuate, like tiny dipoles.

According to the scientists, it is this random flipping behavior that is key to the materials' ability to convert heat into electricity.

"The randomly flipping dipoles impede the movement of heat through the material in much the same way that it is more difficult to move through a disorderly wood than an orderly apple orchard where the trees are lined up in rows," Billinge says. "This low thermal conductivity allows a large temperature gradient to be maintained across the sample, which is crucial to the thermoelectric properties."

When one side of the material comes in contact with heat — say, in the exhaust system of a car — the gradient will cause charge carriers in the thermoelectric material (e.g., electrons) to diffuse from the hot side to the cold side. Capturing this thermally induced electric current could put the "waste" heat to use.

This research may help scientists search for other thermoelectric materials with exceptional properties, since it links the good thermoelectric response to the existence of fluctuating dipoles.

"Our next step will be searching for new materials that show this novel phase transition, and finding other structural signatures for this behavior," Billinge said. "The new tools that allow us to probe nanoscale structures are essential to this research.

"Such studies of complex materials at the nanoscale hold the key to many of the transformative technological breakthroughs we seek to solve problems in energy, health, and the environment."

This research was funded by the DOE Office of Science, the Office of Naval Research, and the National Science Foundation.

####

About Brookhaven National Laboratory
One of ten national laboratories overseen and primarily funded by the Office of Science of the U.S. Department of Energy (DOE), Brookhaven National Laboratory conducts research in the physical, biomedical, and environmental sciences, as well as in energy technologies and national security. Brookhaven Lab also builds and operates major scientific facilities available to university, industry, and government researchers. Brookhaven is operated and managed for DOE’s Office of Science by Brookhaven Science Associates, a limited-liability company founded by the Research Foundation of the State University of New York, for and on behalf of Stony Brook University, the largest academic user of Laboratory facilities; and Battelle Memorial Institute, a nonprofit, applied science and technology organization. Visit Brookhaven Lab's electronic newsroom for links, news archives, graphics, and more (www.bnl.gov/newsroom), or follow Brookhaven Lab on Twitter (twitter.com/BrookhavenLab).

About Columbia Engineering
Columbia University’s Fu Foundation School of Engineering and Applied Science offers programs to both undergraduate and graduate students who undertake a course of study leading to the bachelor's, master's, or doctoral degree in engineering and applied science. With facilities specifically designed and equipped to meet the laboratory and research needs of faculty and students, Columbia Engineering is home to a broad array of basic and advanced research installations, from the Columbia Center for Electron Transport in Molecular Nanostructures to the Columbia Genome Center. These interdisciplinary centers in science and engineering, materials research, nanoscale research, and genomic research are leading the way in their respective fields while individual groups of engineers and scientists collaborate to solve some of society’s more vexing challenges. www.engineering.columbia.edu

For more information, please click here

Contacts:
Columbia Engineering contact:
Holly Evarts
212 854-3206


Brookhaven Lab contact:
Karen McNulty Walsh
631 344-8350

Copyright © Brookhaven National Laboratory

If you have a comment, please Contact us.

Issuers of news releases, not 7th Wave, Inc. or Nanotechnology Now, are solely responsible for the accuracy of the content.

Bookmark:
Delicious Digg Newsvine Google Yahoo Reddit Magnoliacom Furl Facebook

Related News Press

News and information

Study reveals how herpes virus tricks the immune system February 5th, 2016

Hepatitis virus-like particles as potential cancer treatment February 5th, 2016

Organic crystals allow creating flexible electronic devices: The researchers from the Faculty of Physics of the Moscow State University have grown organic crystals that allow creating flexible electronic devices February 5th, 2016

Researchers discover new phase of boron nitride and a new way to create pure c-BN February 5th, 2016

Physics

Polar vortices observed in ferroelectric: New state of matter holds promise for ultracompact data storage and processing February 4th, 2016

The quantum fridge: It all comes down to quantum physics: scientists at TU Wien have analyzed why some gases can be cooled down to extremely low temperatures February 2nd, 2016

Unconventional superconductivity near absolute zero temperature: Quantum critical point could be the reason for high temperature superconductivity February 2nd, 2016

Electrons and liquid helium advance understanding of zero-resistance: Study of electrons on liquid helium systems sheds light on zero-resistance phenomenon in semiconductors February 2nd, 2016

Govt.-Legislation/Regulation/Funding/Policy

Hepatitis virus-like particles as potential cancer treatment February 5th, 2016

Researchers discover new phase of boron nitride and a new way to create pure c-BN February 5th, 2016

Scientists guide gold nanoparticles to form 'diamond' superlattices: DNA scaffolds cage and coax nanoparticles into position to form crystalline arrangements that mimic the atomic structure of diamond February 4th, 2016

Polar vortices observed in ferroelectric: New state of matter holds promise for ultracompact data storage and processing February 4th, 2016

Possible Futures

Hepatitis virus-like particles as potential cancer treatment February 5th, 2016

Scientists guide gold nanoparticles to form 'diamond' superlattices: DNA scaffolds cage and coax nanoparticles into position to form crystalline arrangements that mimic the atomic structure of diamond February 4th, 2016

Using mathematics to improve human health February 3rd, 2016

Scientists have put a high precision blood assay into a simple test strip: Researchers have developed a new biosensor test system based on magnetic nanoparticles February 3rd, 2016

Academic/Education

COD Grad Begins Postdoctoral Fellow at Harvard University: Marsela Jorgolli's Passion for Physics Has Led to a Decade of Academic Research That Continues at Harvard University as a Postdoctoral Fellow February 2nd, 2016

Heriot-Watt's Institute of Photonics & Quantum Sciences uses the Deben Microtest 2 kN tensile stage to characterise ceramics and engineering plastics January 21st, 2016

Multiple uses for the JPK NanoWizard AFM system in the Smart Interfaces in Environmental Nanotechnology Group at the University of Illinois at Urbana-Champaign January 20th, 2016

BioSolar Extends Research Agreement With UCSB for Next Phase of Its Super Battery Technology: Development Effort to Continue Under the Supervision of Nobel Laureate, Dr. Alan Heeger January 13th, 2016

Discoveries

Study reveals how herpes virus tricks the immune system February 5th, 2016

Hepatitis virus-like particles as potential cancer treatment February 5th, 2016

Researchers discover new phase of boron nitride and a new way to create pure c-BN February 5th, 2016

Joint Efforts by Iranian, Malaysian Scientists Produce Antibacterial Coatings for Isolated Areas February 4th, 2016

Materials/Metamaterials

Hepatitis virus-like particles as potential cancer treatment February 5th, 2016

Organic crystals allow creating flexible electronic devices: The researchers from the Faculty of Physics of the Moscow State University have grown organic crystals that allow creating flexible electronic devices February 5th, 2016

Researchers discover new phase of boron nitride and a new way to create pure c-BN February 5th, 2016

February 4th, 2016

Announcements

Study reveals how herpes virus tricks the immune system February 5th, 2016

Hepatitis virus-like particles as potential cancer treatment February 5th, 2016

Organic crystals allow creating flexible electronic devices: The researchers from the Faculty of Physics of the Moscow State University have grown organic crystals that allow creating flexible electronic devices February 5th, 2016

Researchers discover new phase of boron nitride and a new way to create pure c-BN February 5th, 2016

NanoNews-Digest
The latest news from around the world, FREE




  Premium Products
NanoNews-Custom
Only the news you want to read!
 Learn More
NanoTech-Transfer
University Technology Transfer & Patents
 Learn More
NanoStrategies
Full-service, expert consulting
 Learn More











ASP
Nanotechnology Now Featured Books




NNN

The Hunger Project







Car Brands
Buy website traffic