Making something new is never easy. Scientists constantly theorize about new materials, but when the material is manufactured it doesn’t always work as expected. To create a new strategy for designing materials, scientists at the Department of Energy’s Argonne National Laboratory combined two different approaches at two different facilities to synthesize new materials.
This new strategy gives faster feedback on what growth schemes are best, thus shortening the timeframe to manufacture a new, stable material for energy transport and conversion applications.
A recent article in Nature Materials describes how researchers used X-ray scattering during a process called molecular beam epitaxy (MBE) to observe the behavior of atoms as a type of material known as layered oxides were being formed. These observations were then used as data for computational predictions of new materials, leading to insights on how to best combine atoms to form new, stable structures.
“MBE is the construction of new materials one layer at a time—and each layer is one-atom thick. We used a new type of MBE system to observe what happens during the growth of oxide thin films. We found that the layers spontaneously rearrange to reach a lower energy, preferred configuration—but not necessarily the configuration we intended,” said John Freeland, the Argonne physicist who led the team. “Most scientists would not expect layers to move around like this, but this is important information to know when designing new materials.”
In experimenting with a class of oxides known as strontium titanates, the research team found that when they layered titanium on top of two layers of Strontium, the titanium layer switched places with the second strontium layer, thus becoming the center layer. When titanium was layered on multiple layers of strontium, titanium always switched places with the strontium layer directly underneath it (Figures 1 and 2).
Argonne chemist June Hyuk Lee lead the experimental development of the in situ oxide MBE, and Guangfu Luo from the University of Wisconsin-Madison developed the theoretical approach to unraveling the energetics that drive the layer rearrangements.
The research team included expertise from Argonne’s Advanced Photon Source (APS), Center for Nanoscale Materials (CNM), Chemical Sciences and Engineering, and Materials Science, and partners from Northwestern University, the University of Connecticut-Storrs and the University of Wisconsin-Madison, who wanted to understand the driving force behind the rearrangements. Using density functional theory (DFT) and computational resources at the CNM, they calculated and compared the energies of different layer sequences, using the data collected from the MBE system. They found that the actual layer sequences corresponded to the lowest energy configuration. Their computations also showed that layer exchange was not unique to strontium and titanium; in fact, it was expected for many different materials systems. With this understanding, scientists can control—on an atomic level—the growth of oxide thin-films.
“What we have here is a new strategy for materials design and synthesis,” said Argonne materials scientist and article co-author Dillon Fong. “Our combination of in situ X-ray scattering with computational theory can be extended to other layered materials and structures, even theoretical ones that haven’t been made yet because they are challenging to manufacture.”
This new strategy gives faster feedback on what growth strategies are best, thus shortening the timeframe to actual manufacture of a new, stable material.
In the future, Argonne wants to make oxide MBE a tool available to APS facility users for synthesis science. “The APS was instrumental in making our findings possible,” explained Freeland. “The X-rays gave us the quantitative information we needed to plug into the theoretical framework, which in turn will allow us—and other APS users--to make new materials more efficiently.”
Films were grown in the in situ X-ray chamber at Sector 33ID-E of the APS. Calculations were carried out on the Fusion Cluster of Argonne's Laboratory Computing Resource Center at the National Energy Research Scientific Computing Center (NERSC) and on Argonne's Carbon Cluster.
The paper, “Dynamic layer rearrangement during growth of layered oxide films by molecular beam epitaxy,” was published in Nature Materials.
This work was supported by the U.S. Department of Energy Office of Science, and partially supported by the University of Wisconsin Materials Research Science and Engineering Center.
The Advanced Photon Source at Argonne National Laboratory is one of five national synchrotron radiation light sources supported by the U.S. Department of Energy's Office of Science to carry out applied and basic research to understand, predict, and ultimately control matter and energy at the electronic, atomic, and molecular levels, provide the foundations for new energy technologies, and support DOE missions in energy, environment, and national security. To learn more about the Office of Science X-ray user facilities, visit the user facilities directory.
The Center for Nanoscale Materials at Argonne National Laboratory is one of the five DOE Nanoscale Science Research Centers (NSRCs), premier national user facilities for interdisciplinary research at the nanoscale, supported by the DOE Office of Science. 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 and Sandia and Los Alamos National Laboratories.
Argonne National Laboratory seeks solutions to pressing national problems in science and technology. The nation's first national laboratory, Argonne conducts leading-edge basic and applied scientific research in virtually every scientific discipline. Argonne researchers work closely with researchers from hundreds of companies, universities, and federal, state and municipal agencies to help them solve their specific problems, advance America's scientific leadership and prepare the nation for a better future. With employees from more than 60 nations, Argonne is managed by UChicago Argonne, LLC for the U.S. Department of Energy's Office of Science.
DOE's 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 science.energy.gov.
Tona Kunz | Eurek Alert!
First-Ever 3D Printed Excavator Project Advances Large-Scale Additive Manufacturing R&D
30.09.2016 | Oak Ridge National Laboratory
New Multiferroic Materials from Building Blocks
29.09.2016 | National Institute for Materials Science
Heavy construction machinery is the focus of Oak Ridge National Laboratory’s latest advance in additive manufacturing research. With industry partners and university students, ORNL researchers are designing and producing the world’s first 3D printed excavator, a prototype that will leverage large-scale AM technologies and explore the feasibility of printing with metal alloys.
Increasing the size and speed of metal-based 3D printing techniques, using low-cost alloys like steel and aluminum, could create new industrial applications...
Friction stir welding is a still-young and thus often unfamiliar pressure welding process for joining flat components and semi-finished components made of light metals.
Scientists at the University of Stuttgart have now developed two new process variants that will considerably expand the areas of application for friction stir welding.
Technologie-Lizenz-Büro (TLB) GmbH supports the University of Stuttgart in patenting and marketing its innovations.
Friction stir welding is a still-young and thus often unfamiliar pressure welding process for joining flat components and semi-finished components made of...
Optical quantum computers can revolutionize computer technology. A team of researchers led by scientists from Münster University and KIT now succeeded in putting a quantum optical experimental set-up onto a chip. In doing so, they have met one of the requirements for making it possible to use photonic circuits for optical quantum computers.
Optical quantum computers are what people are pinning their hopes on for tomorrow’s computer technology – whether for tap-proof data encryption, ultrafast...
The Fraunhofer Institute for Organic Electronics, Electron Beam and Plasma Technology FEP has been developing various applications for OLED microdisplays based on organic semiconductors. By integrating the capabilities of an image sensor directly into the microdisplay, eye movements can be recorded by the smart glasses and utilized for guidance and control functions, as one example. The new design will be debuted at Augmented World Expo Europe (AWE) in Berlin at Booth B25, October 18th – 19th.
“Augmented-reality” and “wearables” have become terms we encounter almost daily. Both can make daily life a little simpler and provide valuable assistance for...
With the help of artificial intelligence, chemists from the University of Basel in Switzerland have computed the characteristics of about two million crystals made up of four chemical elements. The researchers were able to identify 90 previously unknown thermodynamically stable crystals that can be regarded as new materials. They report on their findings in the scientific journal Physical Review Letters.
Elpasolite is a glassy, transparent, shiny and soft mineral with a cubic crystal structure. First discovered in El Paso County (Colorado, USA), it can also be...
30.09.2016 | Event News
29.09.2016 | Event News
28.09.2016 | Event News
30.09.2016 | Materials Sciences
30.09.2016 | Earth Sciences
30.09.2016 | Life Sciences