Researchers from MIT and collaborating institutions have, for the first time, directly measured the 3D atomic structure of a relaxor ferroelectric.

These materials are key to technologies such as ultrasound, sonar, and high-efficiency sensors, but their complex, disordered structure has remained a mystery for decades.

Relaxor ferroelectrics are prized for their extreme sensitivity to electric fields. Compared with standard crystals, where atoms march in perfect, predictable rows, relaxors are defined by chemical disorder. 

This discovery revealed that the material’s internal polar regions are much smaller and more complex than leading simulations had suggested.

“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,” said James LeBeau, MIT’s Kyocera Professor of Materials Science and Engineering.

“The research community is still developing methods to engineer these materials, but in order to predict the properties those materials will have, you have to know if your model is right,” the corresponding author added.

Chemical disorder mapping

In this new work, the 3D distribution of electric charges in relaxor ferroelectrics was mapped using multi-slice electron ptychography. 

This technique involves scanning a nanoscale electron probe across a material to capture overlapping diffraction patterns. Algorithms then reconstruct these patterns into a high-resolution 3D map of the object’s atomic and polar structure.

This helped to uncover a level of “chemical disorder” previously ignored by standard models. Particularly, the technique allowed the observation of the elusive nanoregions within a lead magnesium niobate-lead titanate alloy.

Through this, the internal atomic interactions that drive the material’s superior energy storage and sensing were mapped. These structural details had been impossible to measure directly until now.

“We do this in a sequential way, and at each position, we acquire a diffraction pattern. That creates regions of overlap, and that overlap has enough information to use an algorithm to iteratively reconstruct three-dimensional information about the object and the electron wave function,” explained Menglin Zhu, co-first author.

More advanced devices

The technique revealed that many of the “polar regions” — the pockets of charge that give the material its power — were much smaller than anyone expected.

Further, integrating this data into computer simulations helped to move beyond “random” models to accurately show how specific chemical species and charge states coordinate to drive the material’s behavior.

“Materials science is incorporating more complexity into the material design process — whether that’s for metal alloys or semiconductors — as AI has improved and our computational tools have become more advanced,” LeBeau stated.

“But if our models aren’t accurate enough and we have no way to validate them, it’s garbage in, garbage out. This technique helps us understand why the material behaves the way it does and validate our models,” the author added. 

With a “validated map” of atomic structures, this discovery is set to accelerate the development of next-generation technologies across multiple industries. This structural clarity will enable the development of more precise medical ultrasound and sonar systems, higher-capacity energy storage systems, and advanced electronic components for faster computing.