Bharat Jalan (left) and Sreejith Nair (right) in their laboratory. Photo: Olivia Hultgren, University of Minnesota.A team led by researchers at the University of Minnesota Twin Cities has developed a first-of-its-kind, breakthrough method that makes it easier to create high-quality metal oxide thin films out of ‘stubborn’ metals that have historically been difficult to synthesize in an atomically precise manner. This research, reported in a paper in Nature Nanotechnology, paves the way for scientists to develop better materials for various next-generation applications including quantum computing, microelectronics, sensors and energy catalysis.
“This is a truly remarkable discovery, as it unveils an unparalleled and simple way for navigating material synthesis at the atomic scale by harnessing the power of epitaxial strain,” said Bharat Jalan, a professor in the University of Minnesota Department of Chemical Engineering and Materials Science and senior author of the paper. “This breakthrough represents a significant advancement with far-reaching implications in a broad range of fields. Not only does it provide a means to achieve atomically precise synthesis of quantum materials, but it also holds immense potential for controlling oxidation-reduction pathways in various applications, including catalysis and chemical reactions occurring in batteries or fuel cells.”
‘Stubborn’ metal oxides, such as those based on ruthenium or iridium, play a crucial role in numerous applications in quantum information sciences and electronics. However, converting them into thin films has proved a challenge for researchers due to the inherent difficulties in oxidizing metals using high-vacuum processes.
The fabrication of these materials has perplexed materials scientists for decades. While some researchers have successfully achieved oxidation, the methods used thus far have been costly, unsafe or have resulted in poor material quality.
But while attempting to synthesize metal oxides using conventional molecular beam epitaxy, a low-energy technique that generates single layers of material in an ultra-high vacuum chamber, the University of Minnesota researchers stumbled upon a ground-breaking revelation. They found that incorporating a concept known as ‘epitaxial strain’ – effectively stretching the metals at the atomic level – significantly simplifies the oxidation process of these stubborn metals.
“This enables the creation of technologically important metal oxides out of stubborn metals in ultra-high vacuum atmospheres, which has been a longstanding problem,” said Sreejith Nair, a chemical engineering PhD student at the University of Minnesota and first author of the paper. “The current synthesis approaches have limits, and we need to find new ways to push those limits further so that we can make better-quality materials. Our new method of stretching the material at the atomic scale is one way to improve the performance of the current technology.”
Although the University of Minnesota team used iridium and ruthenium as examples in this study, their method has the potential to generate atomically precise oxides of any hard-to-oxidize metal. With this ground-breaking discovery, the researchers aim to empower scientists worldwide to synthesize these novel materials.
“When we looked at these metal oxide films very closely using very powerful electron microscopes, we captured the arrangements of the atoms and determined their types,” explained Andre Mkhoyan, another professor in the University of Minnesota Department of Chemical Engineering and Materials Science and author of the paper. “Sure enough, they were nicely and periodically arranged as they should be in these crystalline films.”
This story is adapted from material from the University of Minnesota, with editorial changes made by Materials Today. The views expressed in this article do not necessarily represent those of Elsevier. Link to original source.