Nanotechnology Now

Our NanoNews Digest Sponsors

Heifer International

Wikipedia Affiliate Button

Home > Press > Stressed Nanomaterials Display Unexpected Movement

Kevin Hemker, seated between models representing how atoms are packed within an individual grain in a material, holds a silicon wafer onto which nanocrystalline aluminum thin film specimens have been deposited. Photo: Will Kirk/Homewoodphoto.jhu.edu
Kevin Hemker, seated between models representing how atoms are packed within an individual grain in a material, holds a silicon wafer onto which nanocrystalline aluminum thin film specimens have been deposited. Photo: Will Kirk/Homewoodphoto.jhu.edu

Abstract:
Johns Hopkins researchers have discovered that, under the right conditions, newly developed nanocrystalline materials exhibit surprising activity in the tiny spaces between the geometric clusters of atoms called nanocrystals, from which they are made.

Stressed Nanomaterials Display Unexpected Movement

Baltimore, MD | Posted on March 1st, 2010

This finding, detailed recently in the journal Science, is important because these nanomaterials are becoming more ubiquitous in the fabrication of microdevices and integrated circuits. Movement in the atomic realm can affect the mechanical properties of these futuristic materials—making them more flexible and less brittle—and may alter the material's lifespan.

"As we make smaller and smaller devices, we've been using more nanocrystalline materials that have much smaller crystallites—what materials scientists call grains—and are believed to be much stronger," said Kevin Hemker, professor and chair of Mechanical Engineering in Johns Hopkins' Whiting School of Engineering and senior author of the Science article. "But we have to understand more about how these new types of metal and ceramic components behave, compared to traditional materials. How do we predict their reliability? How might these materials deform when they are subjected to stress?"

The experiments conducted by a former undergraduate research assistant and supervised by Hemker focused on what happens in regions called grain boundaries. A grain or crystallite is a tiny cluster of atoms arranged in an orderly three-dimensional pattern. The irregular space or interface between two grains with different geometric orientations is called the grain boundary. Grain boundaries can contribute to a material's strength and help it resist plastic deformation, a permanent change of shape. Nanomaterials are believed to be stronger than traditional metals and ceramics because they possess smaller grains and, as a result, have more grain boundaries.

Most scientists have been taught that these grain boundaries do not move, a characteristic that helps the material resist deformation. But when Hemker and his colleagues performed experiments on nanocrystalline aluminum thin films, applying a type of force called shear stress, they found an unexpected result. "We saw that the grains had grown bigger, which can only occur if the boundaries move," he said, "and the most surprising part of our observation was that it was shear stress that had caused the boundaries to move."

"The original view," Hemker said, "was that these boundaries were like the walls inside of a house. The walls and the rooms they create don't change size; the only activity is by people moving around inside the room. But our experiments showed that in these nanomaterials, when you apply a particular type of force, the rooms do change size because the walls actually move."

The discovery has implications for those who use thin films and other nanomaterials to make integrated circuits and microelectromechanical systems, commonly called MEMS. The boundary movement shown by Hemker and his colleagues means that the nanomaterials used in these products likely possess more plasticity, higher reliability and less brittleness, but also reduced strength.

"As we move toward making things at much smaller sizes, we need to take into account how activity at the atomic level affects the mechanical properties of the material," Hemker said. "This knowledge can help the microdevice makers decide on the proper size for their components and can lead to better predictions about how long their products will last."

The journal article describing this discovery was inspired by a Johns Hopkins master's thesis produced by Tim Rupert, then a combined bachelor's/master's degree student in mechanical engineering. Rupert, who is now a doctoral student at MIT, is lead author of the Science piece. Along with Hemker, the co-authors are Daniel Gianola, a former doctoral student and postdoctoral fellow in Hemker's lab who is now an assistant professor of materials science and engineering at the University of Pennsylvania; and Y. Gan of the Karlsruhe Institute of Technology in Germany.

Funding for the research was provided by the U.S. Department of Energy and the National Science Foundation.

Related links:

Kevin Hemker's Lab Page: www.me.jhu.edu/hemker/MicroNano/index.html

Johns Hopkins Department of Mechanical Engineering: www.me.jhu.edu/


####

About Johns Hopkins University
The mission of The Johns Hopkins University is to educate its students and cultivate their capacity for life-long learning, to foster independent and original research, and to bring the benefits of discovery to the world.

For more information, please click here

Contacts:
MEDIA CONTACT:
Phil Sneiderman
443-287-9960

Copyright © Johns Hopkins 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

The power of perovskite: OIST researchers improve perovskite-based technology in the entire energy cycle, from solar cells harnessing power to LED diodes to light the screens of future electronic devices and other lighting applications August 18th, 2017

Gold nanostars and immunotherapy vaccinate mice against cancer: New treatment cures, vaccinates mouse in small proof-of-concept study August 18th, 2017

Researchers printed graphene-like materials with inkjet August 17th, 2017

Candy cane supercapacitor could enable fast charging of mobile phones August 17th, 2017

Thin films

Rice University chemists make laser-induced graphene from wood July 31st, 2017

Graduate Students from Across the Country Attend Hands-on NanoCamp: Prominent scientists Warren Oliver, Ph.D., and George Pharr, Ph.D., presented a weeklong NanoCamp for hand-picked graduate students across the United States July 26th, 2017

Studying Argon Gas Trapped in Two-Dimensional Array of Tiny "Cages": Understanding how individual atoms enter and exit the nanoporous frameworks could help scientists design new materials for gas separation and nuclear waste remediation July 17th, 2017

Thinking thin brings new layering and thermal abilities to the semiconductor industry: In a breakthrough for the semiconductor industry, researchers demonstrate a new layer transfer technique called "controlled spalling" that creates many thin layers from a single gallium nitride July 11th, 2017

Govt.-Legislation/Regulation/Funding/Policy

Researchers printed graphene-like materials with inkjet August 17th, 2017

Freeze-dried foam soaks up carbon dioxide: Rice University scientists lead effort to make novel 3-D material August 16th, 2017

2-faced 2-D material is a first at Rice: Rice University materials scientists create flat sandwich of sulfur, molybdenum and selenium August 14th, 2017

Engineers pioneer platinum shell formation process – and achieve first-ever observation August 11th, 2017

Possible Futures

The power of perovskite: OIST researchers improve perovskite-based technology in the entire energy cycle, from solar cells harnessing power to LED diodes to light the screens of future electronic devices and other lighting applications August 18th, 2017

Gold nanostars and immunotherapy vaccinate mice against cancer: New treatment cures, vaccinates mouse in small proof-of-concept study August 18th, 2017

Researchers printed graphene-like materials with inkjet August 17th, 2017

Candy cane supercapacitor could enable fast charging of mobile phones August 17th, 2017

Academic/Education

Two Scientists Receive Grants to Develop New Materials: Chad Mirkin and Monica Olvera de la Cruz recognized by Sherman Fairchild Foundation August 16th, 2017

Moving at the Speed of Light: University of Arizona selected for high-impact, industrial demonstration of new integrated photonic cryogenic datalink for focal plane arrays: Program is major milestone for AIM Photonics August 10th, 2017

Graduate Students from Across the Country Attend Hands-on NanoCamp: Prominent scientists Warren Oliver, Ph.D., and George Pharr, Ph.D., presented a weeklong NanoCamp for hand-picked graduate students across the United States July 26th, 2017

The Physics Department of Imperial College, London, uses the Quorum Q150T to deposit metals and ITO to make plasmonic sensors and electric contact pads July 13th, 2017

MEMS

First Capacitive Transducer with 13nm Gap July 27th, 2017

Bosch announces high-performance MEMS acceleration sensors for wearables June 27th, 2017

Smart multi-layered magnetic material acts as an electric switch: New study reveals characteristic of islands of magnetic metals between vacuum gaps, displaying tunnelling electric current March 1st, 2017

Engineers shrink microscope to dime-sized device February 17th, 2017

Nanoelectronics

GLOBALFOUNDRIES Demonstrates 2.5D High-Bandwidth Memory Solution for Data Center, Networking, and Cloud Applications: Solution leverages 2.5D packaging with low-latency, high-bandwidth memory PHY built on FX-14™ ASIC design system August 9th, 2017

GLOBALFOUNDRIES, Silicon Mobility Deliver the Industry’s First Automotive FPCU to Boost Performance for Hybrid and Electric Vehicles: Silicon Mobility and GF’s 55nm LPx -enabled platform, with SST’s highly-reliable SuperFlash® memory technology, boosts automotive performance, ene August 3rd, 2017

Scientists discover new magnet with nearly massless charge carriers July 29th, 2017

Atomic discovery opens door to greener, faster, smaller electronic circuitry: Scientists find way to correct communication pathways in silicon chips, making them perfect July 27th, 2017

Discoveries

The power of perovskite: OIST researchers improve perovskite-based technology in the entire energy cycle, from solar cells harnessing power to LED diodes to light the screens of future electronic devices and other lighting applications August 18th, 2017

Gold nanostars and immunotherapy vaccinate mice against cancer: New treatment cures, vaccinates mouse in small proof-of-concept study August 18th, 2017

Researchers printed graphene-like materials with inkjet August 17th, 2017

Candy cane supercapacitor could enable fast charging of mobile phones August 17th, 2017

Materials/Metamaterials

Researchers printed graphene-like materials with inkjet August 17th, 2017

Two Scientists Receive Grants to Develop New Materials: Chad Mirkin and Monica Olvera de la Cruz recognized by Sherman Fairchild Foundation August 16th, 2017

Fewer defects from a 2-D approach August 15th, 2017

2-faced 2-D material is a first at Rice: Rice University materials scientists create flat sandwich of sulfur, molybdenum and selenium August 14th, 2017

Announcements

The power of perovskite: OIST researchers improve perovskite-based technology in the entire energy cycle, from solar cells harnessing power to LED diodes to light the screens of future electronic devices and other lighting applications August 18th, 2017

Gold nanostars and immunotherapy vaccinate mice against cancer: New treatment cures, vaccinates mouse in small proof-of-concept study August 18th, 2017

Researchers printed graphene-like materials with inkjet August 17th, 2017

Candy cane supercapacitor could enable fast charging of mobile phones August 17th, 2017

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