Photo by Nancy Wong
King Lab Pioneer Technique to Visualize Anti-Ferroelectric Materials
Professor Sarah King became deeply involved in microscopy because she believes seeing is believing.
“I just love coming up with new ways to look at materials and being able to see things that nobody has seen before.”
Scientists like Dr. King use electron microscopy to study materials to find out how they work and then customize them for various uses. It is crucial to understand the electronic properties of materials to advance cutting-edge technologies. However, researchers have faced challenges in imaging certain kinds of materials and in turn, discovering their true properties and potential.
Now in a recent publication in Science Advances, the King Lab has made significant strides in imaging antiferroelectric materials, a class of materials with unique electrical properties that could open up potential applications in energy storage, sensors, and memory devices.
“It's going to play a critical role in the development of new materials.”
—Asst. Prof. Sarah King
Taking A Better Picture
In electronics and energy storage, antiferroelectric materials are extremely valuable because of their special arrangement of electric dipoles – arrangements of partial positive and negative charges – which perfectly cancel each other, resulting in no net positive or negative polarization in the material. However, applying an electric field to an antiferroelectric material allows you to switch it to a higher energy state where the electric dipoles don’t cancel each other out. This switching behavior makes them particularly fascinating to scientists and engineers looking to unlock their potential.
However, developing these materials has presented challenges, especially when it comes to imaging and characterizing them for modification. Traditional imaging techniques often lack the necessary resolution and contrast to effectively study these materials and their dynamics.
"One of the major hurdles is that we don't have a great way of determining whether something is antiferroelectric because we lack the means to visualize the domains," explains Dr. King. “What we've done in this paper is we have demonstrated a new method for emerging antiferroelectric materials on the nanoscale.”
Determined to see their goals clearly, her lab has now pioneered a fresh approach that enables researchers to finally see their domains.
King and lab member Ruiyu Li adjust settings on instruments in the microscopy lab
Finding the Map
Using an advanced microscopy technique called polarization-dependent photoemission electron microscopy (PD-PEEM), the group was able to image in detail the electronic properties and arrangement of domains in indium(III) selenide (b’-In2Se3), successfully mapping the nanoscale arrangement and orientation of the antiferroelectric domains.
This new method combines polarized light from lasers with electron imaging and offers a more complete picture of a material's properties to those studying it.
Mastering the microscopes and lasers used for such research requires significant time and expertise, and Dr. King acknowledges the hard work and dedication of the students, postdoctoral scholars, and collaborators for the success of this paper, as well the U.S. Department of Energy, Basic Energy Sciences Program who funded the work.
The research was spearheaded by first author, graduate student Joseph Spellberg, who was supported in the lab by UChicago undergraduate chemistry major Lina Kodaimati. Postdoctoral fellow Dr. Prakriti Joshi brought great expertise and support to the team, while graduate student Nasim Mirzajani’s software coding skills were critical to the project.
King shared an anecdote about Spellberg, who initially worked to grasp the way antiferroelectric domains can combine into different macroscopic shapes by drawing pictures in the sand on the beach, trying to understand the process.
“It shows the deep engagement and creativity of our team," explains King.
The group also found a key collaborator in Dr. Liangbo Liang from Oak Ridge National Lab, who's expertise in electronic structure theory helped bridge the gap between experimental and theoretical research, enhancing the group’s understanding of how polarized light interacts with these materials.
Moving Forward with Map in Hand
Thanks to this breakthrough in imaging technology, Dr. King envisions a future in materials science where we can thoroughly explore various aspects like domain switching in antiferroelectric and ferroelectric materials and phase transitions. She's particularly interested in how different properties within materials interact to create ordered states, emphasizing the role order and hierarchy play in domain formation.
"I believe that having new imaging techniques with such high spatial resolution is incredibly powerful. It's going to play a critical role in the development of new materials," says King enthusiastically.
Citation: “Electronic structure orientation as a map of in-plane antiferroelectricity in β′-In2Se3." Joseph L. Spellberg et al., Science Advances, June 14, 2024.
Funding: the U.S. Department of Energy, Basic Energy Sciences Program