For more than a decade, Jiamian Hu has used computer models to predict and understand the microstructure of materials as they form and grow. While they are difficult to see with the naked eye, these microstructures determine the properties of a material, like its hardness or conductivity. As an assistant professor of materials science and engineering at the University of Wisconsin-Madison, Hu studies ferroics, or materials with an orderly polarization or magnetization that can be changed via external force, like an electric or magnetic field.
Typically, Hu models microstructures that form under conditions of equilibrium; for example, those cooled at a slow rate or exposed to a static external field. For his National Science Foundation CAREER Award project, however, Hu wants to model how microstructures form under nonequilibrium conditions, which could lead to new and exciting properties. In particular, he will use a new dynamical phase-field model developed by his research team to understand and predict the properties of materials when they are bombarded by ultrasonic acoustic pulses lasting just one trillionth of a second.
Using the pulses, it may be possible to alter the microstructure of materials, turning electronic insulators into superconductors or opaque materials into transparent substances, among many possibilities. “This would not just be amazing; it’s magical. And with the right materials under the right conditions, I think these changes are entirely possible,” says Hu.
Much of the work will focus on modeling ways to induce complex polar phases in materials, including a state called a polar vortex. Researchers have only observed this state arising spontaneously during materials synthesis. Hu’s computer models will look at heterostructures, or materials made up of stacks of ultrathin layers of ferroics and other materials, to predict which ones will develop vortices or other unconventional polar phases when blasted with ultrasound. These types of materials could become the basis of ultra-high-density vortex-based memory, which could enable the next generation of computers.
Though Hu’s research is computational, he plans to work with experimentalists to investigate some of the materials his models identify for real-world testing.
Hu is also excited about the outreach element of the CAREER Award. He and his students, in collaboration with an educational software company and teachers, are developing classroom modules focused on microstructures for middle and high school science classes. The modules will involve modeling, 3D printing and properties testing, and the group hopes to disseminate the modules to schools throughout Wisconsin.
In fact, Hu has already done some preliminary work on the modules, collaborating with a local high school science teacher and presenting one module at the UW-Madison Precollege Enrichment Opportunity Program for Learning Excellence event in July 2022. The event, which included about 30 Wisconsin high school students from underrepresented backgrounds, featured lightning talks on computational materials science and material microstructure, tours of the 3D-printing facilities in the College of Engineering makerspace, and hands-on simulations on laptops. The students even took home a 3D-printed bi-continuous microstructure to remember the event … and perhaps inspire some future microstructural transformations of their own.
Hu says he hopes the students are excited by science—just like he still is. “Archimedes said, ‘If you give me a lever and a place to stand, I can move the world,’” he says. “That’s one of the coolest things I heard when I was a kid, and that vision, the enormous power of science, is still empowering to me. And now I hope to say, “if you give me an ultrasound that is one trillionth of a second, I can turn one material into another.”
Featured image caption: MS&E Assistant Professor Jiamian Hu will model how microstructures of materials form under nonequilibrium conditions, which could lead to new and exciting properties. Photo credit: Jason Daley.