Navigation Links
Stressed nanomaterials display unexpected movement
Date:2/23/2010

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.

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."


'/>"/>

Contact: Phil Sneiderman
prs@jhu.edu
443-287-9960
Johns Hopkins University
Source:Eurekalert  

Related biology technology :

1. Miami Beach Real Estate Attorney Opens Miami Real Estate Brokerage for International Luxury Miami Beach Condo Buyers From Distressed Sellers
2. EPA announces research strategy to study nanomaterials
3. Quantum dots and nanomaterials: Ingredients for better lighting and more reliable power
4. NPL to create encyclopedia for space nanomaterials
5. Nanomaterials show unexpected strength under stress
6. NanoMaterials Technology to Conduct Process Development Feasibility Study with US Based Emerging Pharmaceutical Company
7. Therapeutic Cells Derived From Reprogrammed (iPS) Stem Cells Display Early Aging
8. Greenway Medical Technologies To Display Live Interoperability Implementations at 2009 DIA Show
9. TrueVision Adds 3D Flat Panel Displays to its Visualization Platform for Refractive-Cataract Surgery
10. American Society of Anesthesiologists Primary Agenda Displayed Says Dr. Barry Friedberg of Cosmetic Surgery Anesthesia
11. Managing Risk Through Quality: Ansell Healthcares Innovative Gammex(R) Glove Range on Display at Arab Health 2009
Post Your Comments:
*Name:
*Comment:
*Email:
Related Image:
Stressed nanomaterials display unexpected movement
(Date:6/28/2017)... ... June 28, 2017 , ... Ovation Fertility continues ... for presentation at the 33rd Annual Meeting of the European Society of ... the world’s top thought leaders in reproductive medicine – are expected to attend ...
(Date:6/28/2017)... ... June 28, 2017 , ... Supplies of the critical medical isotope molybdenum-99 ... the Society of Nuclear Medicine and Molecular Imaging (SNMMI) 2017 annual meeting in Denver, ... used in 30 to 40 million nuclear medicine procedures worldwide every year. (1) ...
(Date:6/27/2017)... ... June 27, 2017 , ... Brain State Technologies, ... Kickstarter campaign on June 15th to fund production of the new B2v2 wearable ... original Kickstarter goal by more than 150% in a little over a week. ...
(Date:6/27/2017)... ... June 27, 2017 , ... Indiana-based ... GX-1 yeast production and fermentation process. The efficiencies created by the newest ... technologies, most notably the ethanol industry wherein individual production plants are planning to ...
Breaking Biology Technology:
(Date:4/11/2017)... , April 11, 2017 NXT-ID, ... security technology company, announces the appointment of independent Directors Mr. ... to its Board of Directors, furthering the company,s corporate ... ... NXT-ID, we look forward to their guidance and benefiting from ...
(Date:4/4/2017)... --  EyeLock LLC , a leader of iris-based identity ... and Trademark Office (USPTO) has issued U.S. Patent No. ... iris image with a face image acquired in sequence ... th issued patent. "The issuance ... multi-modal biometric capabilities that have recently come to market ...
(Date:3/29/2017)... -- higi, the health IT company that operates the largest ... , today announced a Series B investment from BlueCross ... new investment and acquisition accelerates higi,s strategy to create ... health activities through the collection and workflow integration of ... and secures data today on behalf of over 36 ...
Breaking Biology News(10 mins):