Nanotechnology Now

Our NanoNews Digest Sponsors

Heifer International

Wikipedia Affiliate Button

Home > Press > Watching nanosheets and molecules transform under pressure could lead to stronger materials

Wang and colleagues used small angle X-ray diffraction (SAXRD) and wide-angle X-ray diffraction (WAXRD) to observe changes in the molecular structure of wurtzite crystal under pressure.
Wang and colleagues used small angle X-ray diffraction (SAXRD) and wide-angle X-ray diffraction (WAXRD) to observe changes in the molecular structure of wurtzite crystal under pressure.

Abstract:
Researchers have taken a potential step toward creating a new class of exceptionally strong, durable materials that maintain their high-pressure properties -- including strength and superconductivity -- in everyday low-pressure environments.

By Lauren Gold

Watching nanosheets and molecules transform under pressure could lead to stronger materials

Ithaca, NY | Posted on October 20th, 2010

When it comes to tests of strength, graphite -- actually layered sheets of carbon atoms -- fares badly. Subject it to ultra-high pressure, though, and graphite becomes diamond, the hardest substance known, and a uniquely useful material in a variety of applications.

But while diamonds may be forever, most materials that transform under high pressure revert to their original structure when the pressure is lifted -- losing any useful properties they may have gained when the squeeze was on.

Now, by understanding the process behind the transformation itself, from both experimental and theoretical perspectives, researchers have taken a potential step toward creating a new class of exceptionally strong, durable materials that maintain their high-pressure properties -- including strength and superconductivity -- in everyday low-pressure environments.

The research, led by Zhongwu Wang, staff scientist at the Cornell High Energy Synchrotron Source (CHESS) and including Roald Hoffmann, the 1981 chemistry Nobel laureate and Frank H.T. Rhodes Professor of Humane Letters Emeritus, appears in the Oct. 12, issue of the Proceedings of the National Academy of Sciences.

Additional scientists at CHESS, a group in Korea and a postdoctoral associate in the Hoffmann group, Xiao-dong Wen, also contributed.

Researchers frequently use X-ray diffraction, a technique in which X-rays are projected at a structure and captured on film after they pass through or bounce off its surfaces, to determine the static structures of atoms and molecules. But until now, the transformation and interaction between two structures happened in a metaphorical black box, said Wang.

To open the box, researchers focused on wurtzite, a cadmium-selenium crystal in which atoms are arranged in a diamondlike structure and molecules are bonded on the surface. When thin sheets of wurtzite are squeezed under 10.7 gigapascals of pressure, or 107,000 times the pressure on the Earth's surface, their atomic structure transforms into a rock salt-like structure

Subjecting a macro-sized crystal to high pressure can cause it to break (small defects in the crystal structure magnify, causing the structure, and the transformation process, to become irregular) -- so the group's Korean collaborators instead prepared wurtzite nanosheets, which are just 1.4 nanometers thick and defect-free.

As pressure was applied, Wang and colleagues integrated two X-ray diffraction techniques (small- and large-angle X-ray diffraction) to characterize changes in the crystal's surface shape and interior atomic structure, as well as the structural change of surface-bonded molecules.

They first discovered that the nanosheets required three times the pressure to undergo the transformation as the same material in larger crystal form.

They also tested the material's yield strength (the stress level at which it begins to deform), hardness (resistance to scratching or abrading) and elasticity (ability to return to its original form) during the transformation. Understanding how those properties change as the molecules interact could help researchers design stronger, tougher materials, Wang said.

And adding a bonding molecule called a soft ligand to the surface of the high-pressure nanosheets, the researchers observed the effect of that bonding to the nanosheets' internal structure, transformation pressure, and spacing.

Meanwhile, as Wang and colleagues performed the experiments at CHESS, Wen and Hoffmann worked on the corresponding theory behind the transformation interaction.

"Both the experiment and the simulation agree well," Wang said. "Now we know how the atoms move. We understand the intermediate procedure."

The next step is to test ways of blocking the reverse transformation from rock salt back to wurtzite, creating a material that maintains rock salt's unique properties under ambient pressure.

And Wang's experimental process could hold promise for understanding the transformation pathway for other compounds as well.

"It can apply to all other materials," Wang said. "Just follow our way of measurement."

The research was funded by the National Science Foundation.

####

For more information, please click here

Contacts:
Media Contact:
Blaine Friedlander
(607) 254-8093


Cornell Chronicle:
Lauren Gold
(607) 255-9736

Copyright © Cornell University

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

Continuous roll-process technology for transferring and packaging flexible LSI August 29th, 2016

Meteorite impact on a nano scale August 29th, 2016

Designing ultrasound tools with Lego-like proteins August 29th, 2016

A nanoscale wireless communication system via plasmonic antennas: Greater control affords 'in-plane' transmission of waves at or near visible light August 27th, 2016

Govt.-Legislation/Regulation/Funding/Policy

Analog DNA circuit does math in a test tube: DNA computers could one day be programmed to diagnose and treat disease August 25th, 2016

New approach to determining how atoms are arranged in materials August 25th, 2016

Johns Hopkins scientists track metabolic pathways to find drug combination for pancreatic cancer August 25th, 2016

New electrical energy storage material shows its power: Nanomaterial combines attributes of both batteries and supercapacitors August 25th, 2016

Possible Futures

Continuous roll-process technology for transferring and packaging flexible LSI August 29th, 2016

Designing ultrasound tools with Lego-like proteins August 29th, 2016

A nanoscale wireless communication system via plasmonic antennas: Greater control affords 'in-plane' transmission of waves at or near visible light August 27th, 2016

A promising route to the scalable production of highly crystalline graphene films August 26th, 2016

Academic/Education

AIM Photonics Announces Release of Process Design Kit (PDK) for Integrated Silicon Photonics Design August 25th, 2016

Nanotech Security Featured by Simon Fraser University: Company's Anti-Counterfeiting Technology Developed With the Help of University's 4D LABS Materials Research Institute August 21st, 2016

W.M. Keck Foundation awards Cal State LA a $375,000 research and education grant August 4th, 2016

Thomas Swan and NGI announce unique partnership July 28th, 2016

Materials/Metamaterials

A promising route to the scalable production of highly crystalline graphene films August 26th, 2016

Graphene under pressure August 26th, 2016

Unraveling the crystal structure of a -70 Celsius superconductor, a world first: Significant advancement in the realization of room-temperature superconductors August 25th, 2016

Semblant to Present at China Mobile Manufacturing Forum 2016 August 25th, 2016

Announcements

Continuous roll-process technology for transferring and packaging flexible LSI August 29th, 2016

Meteorite impact on a nano scale August 29th, 2016

Designing ultrasound tools with Lego-like proteins August 29th, 2016

A nanoscale wireless communication system via plasmonic antennas: Greater control affords 'in-plane' transmission of waves at or near visible light August 27th, 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