[Image courtesy of Rice/Jieun Kim]
The study, published in Nature Nanotechnology, focused around lead magnesium niobate-lead titanate (PMN-PT). This widely used ceramic material can be used in a range of applications, such as medical imaging (ultrasounds) and energy harvesting to gas sensors and more. The researchers found a “sweet spot” with the material that could enhance medical devices.
According to a post on Rice’s website, PMN-PT excels at converts energy from one form to another. Local dipoles make up the material and create competing energies, breaking the material up into polar nanodomains. These tiny clusters are no bigger than a small virus.
“These self-assembled structures of polarization inside the material are highly responsive to external stimuli due to the chemical complexity of the material and the size of these regions — at their smallest, PMN-PT nanodomains are only 5-10 nanometers,” said Jieun Kim, assistant professor at the Korea Advanced Institute of Science and Technology and the study’s first author. “Nobody really knew what would happen if we shrunk the whole material down to their size.”
As devices shrink, they require ultrathin films of materials like PMN-PT, the researchers say. Instead of immediately deteriorating, PMN-PT performed better when shrunk down to a precise range of 25-30 nanometers (about 10,000 times thinner than a human hair). At this scale, the researchers say the material’s ability to maintain structure and functionality under varying conditions was significantly enhanced.
Using ultrabright X-ray beams at the Advanced Photon Source at Argonne National Laboratory, the researchers probed the material’s atomic structure. In doing so, they observed how nanodomains evolve as the material thins.
These approaches showcase a “Goldilocks zone” side effect with PMN-PT. In this zone, the material’s properties improve before eventually deteriorating. The researchers say this could pave the way for advanced applications like nanoelectromechanical systems, capacitive-energy storage (pulsed power), pyroelectric energy conversion, low-voltage magnetoelectrics and more.
Next, the researchers plan to see how stacking ultrathin PMN-PT layers (plus similar materials) could create new materials with properties that previously didn’t exist in nature.
“Now we know that we could make devices that are smaller and better,” Kim said.
