ORNL finding goes beyond surface of oxide films
Researchers at the Department of Energy lab learned that key surface properties of complex oxide films are unaffected by reduced levels of oxygen during fabrication — an unanticipated finding with possible implications for the design of functional complex oxides used in a variety of consumer products, said Zheng Gai, a member of DOE’s Center for Nanoscale Materials Sciences at ORNL.
The findings are detailed in a paper published in Nanoscale.
While the properties of the manganite material below the surface change as expected with the removal of oxygen, becoming an insulator rather than a metal, or conductor, researchers found that the sample showed remarkably stable electronic properties at the surface. Gai emphasized that the robustness of a surface matters because it is precisely the surface properties that determine, influence and affect the functionality of complex oxides in catalysis and batteries.
“With these materials being a promising alternative to silicon or graphene in electronic devices, the ever-decreasing size of such components makes their surface properties increasingly important to understand and control,” Gai said.
While this work provides a fundamental understanding of a material used and researched for catalysts, oxide electronics and batteries, Gai and lead author Paul Snijders noted that it’s difficult to speculate about possible impacts.
“I always say that in basic science we are discovering the alphabet,” said Snijders, a member of ORNL's Materials Science and Technology Division. “How these letters will be designed into a useful technological book is hard to predict.”
Making this discovery possible was the fact the authors did their experiment using scanning probe microscopy in a vacuum system with no exposure of the samples to the atmosphere. This contrasts with the conventional approach of growing a sample and then installing it in analysis equipment. During such a transfer, scientists expose the material to the water, nitrogen and carbon dioxide in the air.
By studying pristine samples, the ORNL team gained a surprising new understanding of the physics of the material surfaces — an understanding that is necessary to design new functional applications, Snijders said.
Other authors of the paper, titled “Persistent metal-insulator transition at the surface of an oxygen-deficient, epitaxial manganite film,” are Min Gao, Hangwen Guo, Guixin Cao, Wolter Siemons and Thomas Ward of ORNL, Hongjun Gao of the Chinese Academy of Sciences and Jian Shen of Fudan University, China. Min Gao and Snijders contributed equally to this work, which was funded by DOE’s Basic Energy Sciences. A portion of the research was conducted at the Center for Nanophase Materials Sciences. The paper is available at http://pubs.rsc.org/en/content/articlelanding/2013/nr/c3nr02343e.
CNMS is one of the five DOE Nanoscale Science Research Centers supported by the DOE Office of Science, premier national user facilities for interdisciplinary research at the nanoscale. Together the NSRCs comprise a suite of complementary facilities that provide researchers with state-of-the-art capabilities to fabricate, process, characterize and model nanoscale materials, and constitute the largest infrastructure investment of the National Nanotechnology Initiative. The NSRCs are located at DOE's Argonne, Brookhaven, Lawrence Berkeley, Oak Ridge, Sandia and Los Alamos national laboratories. For more information about the DOE NSRCs, please visit http://science.energy.gov/bes/suf/user-facilities/nanoscale-science-research-centers.
UT-Battelle manages ORNL for DOE's Office of Science. The Office of Science is the single largest supporter of basic research in the physical sciences in the United States and is working to address some of the most pressing challenges of our time. For more information, please visit http://science.energy.gov/.
All latest news from the category: Materials Sciences
Materials management deals with the research, development, manufacturing and processing of raw and industrial materials. Key aspects here are biological and medical issues, which play an increasingly important role in this field.
innovations-report offers in-depth articles related to the development and application of materials and the structure and properties of new materials.
In the quantum realm, not even time flows as you might expect
New study shows the boundary between time moving forward and backward may blur in quantum mechanics. A team of physicists at the Universities of Bristol, Vienna, the Balearic Islands and…
Hubble Spots a Swift Stellar Jet in Running Man Nebula
A jet from a newly formed star flares into the shining depths of reflection nebula NGC 1977 in this Hubble image. The jet (the orange object at the bottom center…