MIT researchers and collaborators have directly characterized the three-dimensional atomic and polar structure of a relaxor ferroelectric using a technique called multislice electron ptychography, reporting that key polarization features are smaller than leading simulations predicted—results that could help refine models used to design future sensing, computing and energy devices.
Relaxor ferroelectrics have been used for decades in technologies including ultrasound imaging, microphones and sonar systems, but researchers have struggled to directly measure the atomic-scale origins of their unusual properties.
A team led by Massachusetts Institute of Technology materials scientist James LeBeau reports it has now directly characterized the three-dimensional atomic structure of a relaxor ferroelectric for the first time, using an electron microscopy method known as multislice electron ptychography (MEP). The work was described by MIT News and distributed by ScienceDaily, both citing a paper published in Science titled “Bridging experiment and theory of relaxor ferroelectrics with multislice electron ptychography.”
According to the MIT account, the researchers scanned a lead magnesium niobate–lead titanate (PMN-PT) alloy—a relaxor ferroelectric used in applications such as sensors and actuators—by moving a nanoscale probe of high-energy electrons across the sample and measuring diffraction patterns at each position. Using overlaps between adjacent measurements, the team reconstructed a three-dimensional view of the material’s structure.
The MEP measurements revealed a hierarchy of chemical and polar structures spanning atomic to mesoscopic scales, and the researchers found that many regions of differing polarization were much smaller than predicted by leading simulations. The team said it then incorporated the new experimental measurements into computer simulations to refine models and improve agreement with observations.
“Now that we have a better understanding of exactly what’s going on, we can better predict and engineer the properties we want materials to achieve,” LeBeau said in MIT’s release.
Co-first authors Michael Xu and Menglin Zhu said the experiments also highlighted chemical disorder that prior modeling had not fully captured.
The author list described by MIT includes collaborators from MIT as well as the University of Alabama at Birmingham, Rice University and the University of Pennsylvania, among others.
MIT and ScienceDaily reported that the work was supported in part by the U.S. Army Research Laboratory and the U.S. Office of Naval Research, and that it also used MIT.nano facilities. Those releases also describe the broader significance as a way to validate and improve models for complex materials, with potential long-term implications for memory storage, sensing and energy technologies.
