Materials known as relaxer ferroelectrics have played an important role in technologies such as ultrasound imaging, microphones, and sonar for decades. Its extraordinary performance comes from the way the atoms inside are arranged. However, it is extremely difficult to directly measure its internal structure, forcing scientists to rely on incomplete models.
Now, researchers at MIT and a joint research institute have mapped the three-dimensional atomic structure of a relaxor ferroelectric for the first time. The result is scienceprovides a clear foundation for improving models used in the design of future computing systems, energy devices, and advanced sensors.
“Now that we can understand exactly what is going on, we can better predict and design the properties we want to achieve in our materials,” said corresponding author James LeBeau, Kyocera Professor of Materials Science and Engineering at MIT. “The research community is still developing ways to process these materials, but we need to know whether our models are correct to predict the properties these materials will have.”
Revealing hidden charge patterns in complex materials
In the study, the team used cutting-edge imaging techniques to examine how charge is distributed throughout the material. What they discovered overturned previous assumptions.
“We realized that the chemical disorder observed in our experiments had not been fully considered until now,” said co-first authors Michael Xu PhD ’25 and Menglin Zhu. They are both postdoctoral fellows at MIT. “Working with our collaborators, we were able to refine our model by integrating experimental observations and simulations to better predict what we would observe in experiments.”
The research team also included Colin Gilgenbach and Bridget R. Denser, doctoral students at the Massachusetts Institute of Technology, majoring in materials science and engineering. Yubo Chi, assistant professor at the University of Alabama at Birmingham. Jieun Kim, assistant professor at the Korea Institute of Science and Technology. Jiahao Zhang, former doctoral student at the University of Pennsylvania. Lane W. Martin, Professor at Rice University. Andrew M. Rappe, Professor, University of Pennsylvania.
Exploration of disordered matter at the atomic scale
Computer models have long suggested that when an electric field is applied to relaxor ferroelectrics, interactions between positively and negatively charged atoms within small regions help create strong energy storage and sensing capabilities. Until now, it has not been possible to directly observe these nanoscale regions.
To investigate further, the researchers focused on a lead magnesium niobate-lead titanate alloy, a material widely used in sensors, actuators, and defense systems. They applied an advanced technique called multislice electronic ptychography (MEP). The method involves scanning a nanoscale beam of high-energy electrons across a material and recording the resulting diffraction pattern.
“We do this in sequence and obtain a diffraction pattern at each position,” Zhu explains. “This creates an overlapping region that contains enough information to iteratively reconstruct three-dimensional information about the object and electron wave functions using an algorithm.”
Using this approach, the team revealed a hierarchy of chemical and polar structures, from individual atoms to larger mesoscopic features. They also found that the regions with different polarizations were significantly smaller than predicted by previous simulations. By incorporating these observations into the model, the researchers were able to improve how well their simulations matched real-world behavior.
“Previously, these models had essentially random regions of polarization, but we didn’t know how those regions correlated with each other,” Xu says. “Now we can convey that information and see how individual chemical species modulate their polarization depending on the charge state of their atoms.”
Aiming for better materials for future technology
Zhu said the findings highlight the growing power of electronic ptychography to explore complex and disordered materials and could lead to new areas of research.
“This research is the first time that we have been able to directly link the three-dimensional polar structure of relaxor ferroelectrics to molecular dynamics calculations using electron microscopy,” says Xu. “We further demonstrate that this technique can be used to obtain three-dimensional information from samples.”
The research team believes the technique could eventually help scientists design materials with tailored electronic properties to improve technologies such as storage, sensing systems and energy devices.
“As AI advances and computational tools become more sophisticated, materials science is building more complexity into the material design process, whether it’s alloys or semiconductors,” LeBeau says. “But if the model isn’t accurate enough and there’s no way to validate it, it’s just garbage in the garbage. This technology helps us understand why materials behave the way they do and validate the model.”
This research was supported in part by the U.S. Army Research Laboratory, the U.S. Office of Naval Research, the U.S. Department of the Army, and a National Science Graduate Fellowship. The research also utilized facilities at MIT.nano.
