Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:


Nanowires highly 'anelastic,' research shows


Researchers from Brown University and North Carolina State University have found that nanowires made of zinc oxide are highly anelastic, meaning they return to shape slowly after being bent, rather that snapping right back. The findings, published in the journal Nature Nantechnology, add one more to the growing list of interesting properties found in nanoscale wires, tiny strands thousands of times thinner than a human hair.

"What's surprising here is the magnitude of the effect," said Huajian Gao, the Walter H. Annenberg Professor of Engineering and a coauthor of a new paper describing the research. "Anelasticity is present but negligible in many macroscale materials, but becomes prominent at the nanoscale. We show an anelastic effect in nanowires that is four orders of magnitude larger than what is observed in even the most anelastic bulk materials."

Zinc oxide nanowires return to shape slowly after being bent, new research from Brown and NC State shows. That property, called anelasticity, suggests that nanowires might be good in applications that require absorption of shocks or vibrations.

Credit: Zhu lab / NC State

The findings are significant in part because anelastic materials are good absorbers of kinetic energy. These results suggest that nanowires could be useful in damping shocks and vibrations in a wide variety of applications.

"During the last decade, zinc oxide nanowire has been recognized as one of the most important nanomaterials with a broad range of applications such as mechanical energy harvesting, solar cells, sensors and actuators," Gao said. "Our discovery of giant anelasticity and high energy dissipation in zinc oxide nanowires adds a new dimension to their functionality."

The experiments for the study were done in the lab of Yong Zhu, an associate professor of mechanical and aerospace engineering at NC State. Zhu and his colleagues used a delicate apparatus to bend nanowires under a scanning electron microscope.

The work showed that, after the bending strain was released, the wires returned to about 80 percent of their original shape quickly. But they recovered the rest of their original shape much more slowly, over the course of up to 20 or 30 minutes. That is a far more prominent anelastic effect than is common at the macroscale.

To understand why the effect is so prominent, Zhu and his team worked with Gao's lab at Brown, which specializes in theoretical modeling of nanoscale systems. The model that Gao and his colleagues developed suggests that the anelasticity is a result of impurities in the wires' crystal lattice.

Lattice impurities come in two forms. There are vacancies, where atoms are missing from the lattice; and there are interstitials, where the lattice has extra atoms. When a wire is bent to form an arch, there's higher compressive strain on the underside of the arch compared to the upper side. The compression pushes interstitial atoms toward the outside edge, and draws the vacancies toward the inside. When the strain is released, those impurities migrate back to where they started.

That migration takes a bit of time, which is why the wire returns to shape slowly. Because nanowires are so small, the impurities need only travel a short distance to generate a perceptible anelastic effect, which is why the effect is so much more pronounced at the nanoscale compared to the macroscale.

To further test whether the anelasticity was rooted in impurities, the team tested wires made from a different material--silicon doped with boron impurities. Like the zinc oxide nanowires, the doped silicon also proved to be anelastic.

The findings suggest that anelasticity is likely a common property of single-crystal nanowires. "One reviewer [of our paper] commented that this is a new important page in the book on mechanics of nanostructures," Zhu said. "The factors that favor anelasticity, such as high strain gradient, short diffusion distance and large diffusivity of point defects, are all prominently present in nanowires".


Other authors on the paper were Guangming Cheng, Qingquan Qin, Jing Li, Feng Xu and Elizabeth C. Dickey from NC State, and Chunyang Miao and Hamed Haftbaradaran from Brown.

The research was supported by the National Science Foundation.

Kevin Stacey | EurekAlert!

More articles from Materials Sciences:

nachricht Researchers demonstrate existence of new form of electronic matter
15.03.2018 | University of Illinois at Urbana-Champaign

nachricht Boron can form a purely honeycomb, graphene-like 2-D structure
15.03.2018 | Science China Press

All articles from Materials Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Locomotion control with photopigments

Researchers from Göttingen University discover additional function of opsins

Animal photoreceptors capture light with photopigments. Researchers from the University of Göttingen have now discovered that these photopigments fulfill an...

Im Focus: Surveying the Arctic: Tracking down carbon particles

Researchers embark on aerial campaign over Northeast Greenland

On 15 March, the AWI research aeroplane Polar 5 will depart for Greenland. Concentrating on the furthest northeast region of the island, an international team...

Im Focus: Unique Insights into the Antarctic Ice Shelf System

Data collected on ocean-ice interactions in the little-researched regions of the far south

The world’s second-largest ice shelf was the destination for a Polarstern expedition that ended in Punta Arenas, Chile on 14th March 2018. Oceanographers from...

Im Focus: ILA 2018: Laser alternative to hexavalent chromium coating

At the 2018 ILA Berlin Air Show from April 25–29, the Fraunhofer Institute for Laser Technology ILT is showcasing extreme high-speed Laser Material Deposition (EHLA): A video documents how for metal components that are highly loaded, EHLA has already proved itself as an alternative to hard chrome plating, which is now allowed only under special conditions.

When the EU restricted the use of hexavalent chromium compounds to special applications requiring authorization, the move prompted a rethink in the surface...

Im Focus: Radar for navigation support from autonomous flying drones

At the ILA Berlin, hall 4, booth 202, Fraunhofer FHR will present two radar sensors for navigation support of drones. The sensors are valuable components in the implementation of autonomous flying drones: they function as obstacle detectors to prevent collisions. Radar sensors also operate reliably in restricted visibility, e.g. in foggy or dusty conditions. Due to their ability to measure distances with high precision, the radar sensors can also be used as altimeters when other sources of information such as barometers or GPS are not available or cannot operate optimally.

Drones play an increasingly important role in the area of logistics and services. Well-known logistic companies place great hope in these compact, aerial...

All Focus news of the innovation-report >>>



Industry & Economy
Event News

Ultrafast Wireless and Chip Design at the DATE Conference in Dresden

16.03.2018 | Event News

International Tinnitus Conference of the Tinnitus Research Initiative in Regensburg

13.03.2018 | Event News

International Virtual Reality Conference “IEEE VR 2018” comes to Reutlingen, Germany

08.03.2018 | Event News

Latest News

Wandering greenhouse gas

16.03.2018 | Earth Sciences

'Frequency combs' ID chemicals within the mid-infrared spectral region

16.03.2018 | Physics and Astronomy

Biologists unravel another mystery of what makes DNA go 'loopy'

16.03.2018 | Life Sciences

Science & Research
Overview of more VideoLinks >>>