Research on Imperfections and Exsolution Provides Insights into New Materials

William Bowman and Komal Syed

Jan. 31, 2022 – A material’s imperfections and defects at the atomic and nano scale can determine the behavior of that material. By engineering these defects, researchers can tune and optimize the electrical, optical, chemical and magnetic performance of materials to make better gadgets or build better technologies.

William Bowman, UC Irvine assistant professor of materials science and engineering, and Komal Syed, Ph.D. ‘21 in materials science and engineering, have conducted research that demonstrates the importance of complex nanoscale materials and defects in defining the behaviors of next-generation electrical and electrochemical devices, such as fuel cells, electrolyzers and memristors. They’ve published their work on optimizing materials’ defects in the journals Advanced Functional Materials and Nanoscale.

The researchers explored materials created by an advanced synthesis process called exsolution, in which a starting material can be intentionally decomposed into a unique composite material containing multiple different new phases. Bowman and Syed explained that this process is gaining a lot of attention from scientists and engineers because it is a scalable approach to making a wide range of novel nanomaterials and nanocomposites with unprecedented functionality.

For example, exsolution has been primarily used to enhance the activity and durability of catalytic surfaces. Bowman said, “Our works, in collaboration with former MIT Ph.D. student Jiayue Wang, used a variant of the exsolution process that creates nanoparticles below a material’s surface to alter the properties of the bulk material. We ultimately demonstrated that bulk exsolution can provide new opportunities to tune electrical and magnetic properties of nanocomposite materials.”

Their most recent work, led by Syed when she was completing her doctorate at UCI, and published in Nanoscale, focused on the diversity of nanostructures formed during the exsolution process using atomic-resolution structural and chemical analysis. This research followed their prior work led by Wang and published in the journal Advanced Functional Materials, which demonstrated that exsolution in a perovskite (a mineral containing lanthanum strontium iron and oxygen) thin film creates a network of iron particles just 10 billionths of a meter in size connected by even smaller highly conductive channels.

“In particular, the electronic conductivity of the nanocomposite was shown to increase by more than 100 times after exsolution,” said Syed. “Together, these works are relevant to materials scientists and engineers motivated to design nanocomposites with superior functionality in information processing and storage.”

Funding for this work was provided by the Samueli School of Engineering, the U.S. Department of Education Graduate Assistance in Areas of National Need (GAANN) Fellowship, and the Exelon Corporation via the MIT Energy Initiative Seed Fund Program. The use of facilities and instrumentation included the Irvine Materials Research Institute, which is supported in part by the National Science Foundation Materials Research Science and Engineering Center at UCI.

– Tonya Becerra