While studying a thin film material called strontium stannate (SrSnO3), University of Minnesota researchers noticed a remarkable creation of a nano-scale checkerboard pattern similar to structures made in expensive, complex processes. Their results demonstrate the reasonable ability to design similar self-assembled structures with extensive applications in materials for electronics and optical devices. Credit: Jalan Group, University of Minnesota
A team led by University of Minnesota Twin Cities researchers has discovered an innovative one-step process for creating products with unique properties, called metamaterials. Their results demonstrate the reasonable ability to design self-assembled structures similar to the ability to create “built-to-order” nanostructures for wide application in electronics and optical devices.
The research was published and featured on cover Nano Letters, a peer-reviewed scientific journal published by the Chemical Society of America.
In general, metamaterials are laboratory-manufactured materials to provide specific physical, chemical, electrical and optical properties that cannot be traced in naturally occurring materials. These materials can have unique properties that make them ideal for a variety of applications from optical filters and medical devices to aircraft sound protection and infrastructure inspection. These nano-scale materials are typically carefully manufactured in a dedicated clean room environment over days and weeks in a multi-step manufacturing process.
In this new research, the University of Minnesota team studied a thin film material called strontium stannate or SrSnO3. During their research, they observed a remarkable formation of a checkerboard pattern at a nano scale similar to the metamaterial structures formed in the costly, multifactorial process.
“At first we thought this was a mistake, but it wasn’t long before we realized that the occasional pattern is a combination of two levels of the same material with different crystal structures,” said Bharat Jalan, senior. author of the study and expert in material synthesis who is the Shell Chair in the Department of Chemical Engineering and Materials Science of the University of Minnesota. “After consulting with colleagues at the University of Minnesota, the University of Georgia, and New York City University, we realized that we may have discovered something very special that some unique applications may have. ”
The material was funly organized in an ordered structure as it changed from one stage to another. Through the process known as “first-order structural phase transition”, the material moved to a mixed phase in which some parts of the system completed the transition and others did not.
“These nanoscale seasonal patterns are a direct result of first-order structural phase transition in this material,” said Professor Richard James, University of Minnesota aerospace engineering and mechanics, co-author of the study and High distinguished professor of McKnight University. “For the first time, our work enables a number of opportunities to use variable-level structural transformations with nanoelectronic and photonic systems.”
In fact, the team demonstrated a process for the first ever self-assembled tunable nanostructure to create metamaterials in just one step. The researchers were able to store the cost of electrical buildings within a single film using temperature and laser waves. They effectively produced a variable photonic crystal material with a efficiency of 99 percent.
Using high-resolution electric microscopes, the researchers determined the specific structure of the material.
“We found that the boundaries between these crystalline levels were largely defined at an atomic scale, which is remarkable for a self-assembling process,” said Dr. Andre Mkhoyan, co-author of the study, an expert in the advanced electronic microscope, and Chair of Ray D. and Mary T. Johnson / Mayon Plastics in the Department of Chemical Engineering and Materials Science at the University of Minnesota.
The researchers are now looking at future applications for their discovery in optical and electronic devices.
“When we started this research, we never thought about these applications. We were guided by the fundamental study of the physics of the material, ”said Jalan. “Now, all of a sudden, we seem to have opened up a whole new field of research, driven by the potential for many new and exciting applications. ”
Details: “Self-assembled Time Nanostructures Using Martensitic Stage Transformations” by Abhinav Prakash, Tianqi Wang, Ashley Bucsek, Tristan K. Truttmann, Alireza Fali, Michele Cotrufo, Hwanhui Yun, Jong-Woo Kim, Philip J. Ryan , K. Andre Mkhoyan, Andrea Alù, Yohannes Abate, Richard D. James and Bharat Jalan, 2 December 2020, Nano Letters.
DOI: 10.1021 / acs.nanolett.0c03708
In addition to Jalan, the team included University of Minnesota researchers Abhinav Prakash, Ashley Bucsek, Tianqi Wang, Tristan K. Truttmann, Hwanhui Yun, K. Andre Mkhoyan, and Richard James; University of Georgia researchers Alireza Fali and Yohannes Abate; New York City University researchers Michele Cotrufo and Andrea Alù; and Argonne Jong-Woo Kim and Philip J. Ryan National Laboratory researchers.
The research was funded primarily by the National Science Foundation (NSF), and the Air Force Office of Scientific Research (AFOSR) with additional support from the University of Minnesota Institute on the Environment, Norway Centennial Chair Program, and two Vannevar Bush Faculty Fellowships. . Work at the University of Minnesota including thin film identification was supported by the U.S. Department of Energy. Parts of the research were conducted at the Minnesota Nano Center and Character Facility at the University of Minnesota, part-funded by the National Science Foundation. Additional work was completed at Advanced Photon Source, a Science Office User Resource operated for the U.S. Department of Energy Science Office by the Argonne National Laboratory.