Navigation Links
Tiny wires change behavior at nanoscale
Date:8/29/2011

Thin gold wires often used in high-end electronic applications are wonderfully flexible as well as conductive. But those qualities don't necessarily apply to the same wires at the nanoscale.

A new study from Rice University finds gold wires less than 20 nanometers wide can become "brittle-like" under stress. It appears in the journal Advanced Functional Materials.

The paper by Rice materials scientist Jun Lou and his lab shows in microscopic detail what happens to nanowires under the kinds of strain they would reasonably undergo in, for instance, flexible electronics.

Their technique provides a way for industry to see just how nanowires made of gold, silver, tellurium, palladium and platinum are likely to hold up in next-generation nanoelectronic devices.

Lou and his team had already established that metal wires have unique properties on the nanoscale. They knew such wires undergo extensive plastic deformation and then fracture on both the micro- and nanoscale. In that process, materials under stress exhibit "necking"; that is, they deform in a specific region and then stretch down to a point before they eventually break.

"Gold is extremely ductile," said Lou, an assistant professor of mechanical engineering and materials science. "That means you can stretch it, and it can withstand very large displacement.

"But in this work, we discovered that gold is not necessarily very ductile at the nanoscale. When we stress it in a slightly different way, we can form a defect called a twin."

The term "twinning" comes from the mirrorlike atomic structure of the defect, which is unique to crystals. "At the boundary, the atoms on the left and right sides exactly mirror each other," Lou said. Twins in nanowires show up as dark lines across the wire under an electron microscope.

"The material is not exactly brittle, like glass or ceramic, which fracture with no, or very little, ductility," he said. "In this case, we call it brittle-like, which means it has significantly reduced ductility. There's still some, but the fracture behavior is different from regular necking."

Their experiments on 22 gold wires of less than 20 nanometers involved the delicate operation of clamping them to a transmission electron microscope/atomic force microscope sample holder and then pulling them at constant loading speeds. Twins appeared under the shear component of the stress, which forced atoms to shift at the location of surface defects and led to a kind of nanoscale tectonic fault across the wire.

"Once you have those kinds of damage-initiation sites formed in the nanowire, you will have a lot less ductility. The metal will fracture prematurely," Lou said. "We didn't expect such twin-boundary formations would have such profound effects."

With current technology, it's nearly impossible to align the grip points on either side of the wire, so shear force on the nanowires was inevitable. "But this kind of loading mode will inevitably be encountered in the real world," he said. "We cannot imagine all the nanowires in an application will be stressed in a perfectly uniaxial way."

Lou said the results are important to manufacturers thinking of using gold as a nanomechanical element. "Realistically, you could have some off-axis angle of stress, and if these twins form, you would have less ductility than you would expect. Then the design criteria would have to change.

"That's basically the central message of this paper: Don't be fooled by the traditional definition of 'ductile,'" he said. "At the nanoscale, things can happen differently."


'/>"/>

Contact: David Ruth
druth@rice.edu
713-348-6327
Rice University
Source:Eurekalert

Related biology technology :

1. Nanowires get into the groove
2. Piezoelectric nanowires allow electrical signals to be produced from mechanical actions
3. With a simple coating, nanowires show a dramatic increase in efficiency and sensitivity
4. Penn research advances understanding of lead selenide nanowires
5. Engineers create vibrant colors in vertical silicon nanowires
6. Novel nanowires boost fuel cell efficiency
7. Biological nanowires expedite future fuel production
8. Major advance in understanding how nanowires form
9. Stretched rubber offers simpler method for assembling nanowires
10. Nanowires exhibit giant piezoelectricity
11. New ultra-clean nanowires have great potential
Post Your Comments:
*Name:
*Comment:
*Email:
(Date:9/14/2017)... Maryland (PRWEB) , ... September ... ... proudly announces the launch of its CliniControl™ (CC) product portfolio, clinically-relevant starting ... accelerating clinical translation of human Mesenchymal Stem/Stromal Cell (hMSC)-based therapies. The CliniControl ...
(Date:9/14/2017)... ... September 14, 2017 , ... AxioMed is pleased ... Australia. Dr. Steven Yang completed the procedure on a 35-year-old female patient suffering ... lumbar disc at level L5-S1. The patient failed conservative treatments prior to undergoing ...
(Date:9/14/2017)... ... September 14, 2017 , ... AIM Global, the worldwide standards agency for ... won the 2017 Case Study Competition for AIDC. The award is given to ... risk” and push the adoption of automated data collection systems further. The TRACTUS ...
(Date:9/13/2017)... (PRWEB) , ... September 13, 2017 , ... ... with the life sciences industry to improve patient outcomes and quality of life ... & impurities, has been named a US expert to the International Standards ...
Breaking Biology Technology:
(Date:4/11/2017)... No two people are believed to ... York University Tandon School of Engineering and Michigan ... partial similarities between prints are common enough that ... and other electronic devices can be more vulnerable ... in the fact that fingerprint-based authentication systems feature ...
(Date:4/5/2017)... KEY FINDINGS The global market ... CAGR of 25.76% during the forecast period of 2017-2025. ... for the growth of the stem cell market. ... MARKET INSIGHTS The global stem cell market is segmented ... The stem cell market of the product is segmented ...
(Date:3/30/2017)... -- Trends, opportunities and forecast in this market to ... AFIS, iris recognition, facial recognition, hand geometry, vein recognition, ... industry (government and law enforcement, commercial and retail, health ... and by region ( North America , ... , and the Rest of the World) ...
Breaking Biology News(10 mins):