Exciting material properties in complex nanostructures could dissipate energy

Researchers from the University of Texas at Austin and North Carolina State University have discovered for the first time a unique property in complex nanostructures that has so far only been found in simple nanostructures. In addition, they have revealed the internal mechanics of the materials that make this property possible.

In a new paper published this week in the Proceedings of the National Academy of Sciences, the researchers found these properties in oxide-based “nanogrids,” which are tiny, hollow materials that resemble things like sea sponges in structure.

“This has been seen before in simple nanostructures, like a nanowire that is about 1,000 times thinner than a hair,” said Yong Zhu, a professor in the Department of Mechanical and Aerospace Engineering at NC State, and one of the lead authors on the paper. “But this is the first time we’ve seen it in a 3D nanostructure.”

The research: The phenomenon in question is called anelasticity. It relates to how materials react to loads over time. When the materials studied in this paper were bent, small defects moved slowly in response to the stress gradient. When the stress is released, the small defects slowly return to their original positions, resulting in the anelastic behavior.

The researchers also discovered that as these defects move back and forth, they unlock energy-dissipating characteristics. This means that they can spread things like pressure waves and vibrations.

Why it matters: The material could one day act as a shock absorber, but because it’s so light and thin, it would be on a very small scale. The researchers say it could make sense as part of chips for electronics or other integrated electronic devices.

“You could potentially place this material under the semiconductor chips and protect them from external impacts or vibrations,” said Chih-Hao Chang, an associate professor in the Walker Department of Mechanical Engineering at UT Austin.

What’s next: Now that these anelastic properties have been discovered, the next step is to control them. The researchers will investigate the geometry of the nanostructures and experiment with different strain conditions to see how to optimize the anelastic performance for energy dissipation applications.

The team: From UT Austin, Chang and I-Te Chen, a former PhD student; and from NC State, Zhu, Felipe Robles Poblete and Abhijeet Bagal, both former PhD students. The research was supported by grants from the National Science Foundation.

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