Signature line: Savannah Mitchem
Uncover the properties of complex materials by combining X-ray technology and machine learning.
Although crystal and glass dishes look similar on the outside, their internal structure is very different. Crystals are made up of perfectly ordered repeating patterns of atoms, whereas glasses exhibit a more disordered, fluid-like structure.
For decades, scientists have been puzzled by glasses: how they form, what they look like, and why they behave the way they do. Because glasses exist at the exact intersection of liquid and solid, their properties elude traditional methods of classifying and understanding the behavior of materials.
Even more complex and elusive is a phase of material called Bragg glass. It exhibits both the ordered properties of a crystal and the disordered properties of a glass. Scientists at the U.S. Department of Energy's (DOE) Argonne National Laboratory, along with collaborators at Cornell University and Stanford University, recently discovered experimental evidence for the presence of a Bragg glass phase in the material.
The research team used X-ray temperature clustering, a new machine learning data analysis tool developed at Cornell University, to identify subtle features of Bragg glass in large amounts of X-ray scattering data.
Their results contribute to large-scale efforts in modern materials science to study the properties of glasses. Glass' mysterious structure creates material properties that make it useful in applications such as electronics, aerospace engineering, architecture, medicine, and nuclear waste management. This study also demonstrates the potential of machine learning algorithms as powerful tools for discovery in the big data era.
“We can collect large amounts of X-ray data in a short amount of time, but when we manually analyze the data, we can't see the trees for the trees,” said author Ray Osborn, a senior physicist in Argonne University's Department of Materials Science. “It may become impossible to see.” About research. ,war “His combination of state-of-the-art X-ray and computational techniques allowed us to reveal unique features of the Bragg glass phase.”
The atomic structures of all crystals, including diamonds, table salt, and even snowflakes, exhibit what scientists call long-range order, in which specific patterns of atoms repeat in three dimensions throughout matter. . In this study, the researchers searched for Bragg glass states in crystals based on his ErTe.3This structure has a certain long-range order that scientists call charge density waves (CDWs).
“By combining cutting-edge X-ray and computational techniques, we were able to uncover unique features of the Bragg glass phase.” — Senior Physicist Ray Osborn
About 30 years ago, it was theorized that CDW materials could retain a Bragg glass state if a little chaos was introduced into their ordered structure. When creating the sample used in this experiment, the Stanford University scientist randomly dispersed palladium atoms into his ErTe.3 Crystals impose this kind of disorder.
Scientists at Argonne's Advanced Photon Source (APS), a DOE Office of Science User Facility, used the 6-ID-D beamline to perform X-ray scattering on the sample, and used the 6-ID-D beamline to 3D structural data was measured.
In X-ray scattering experiments, when patterns in a sample's structure repeat, scientists see what are called Bragg peaks in the data. “The term Bragg glass is almost an oxymoron. “Bragg” refers to the sharp Bragg peaks seen in perfect crystals, indicating long-range order. And within the glass, we see broader, more diffuse features that exhibit local patterns,” said Matthew Krogstad, assistant physicist at APS and author of the study. I am. “But in Bragg glasses, the characteristics of each type are displayed simultaneously.”
The researchers performed X-ray scattering measurements on the samples at temperatures ranging from 30K to 300K, recording how the structure of the samples changed. Subsequent machine learning analysis at Cornell University showed that the sample froze at a specific transition temperature, retaining significant long-range order, while also exhibiting local features characteristic of Bragg glasses. Confirmed.
“You can think of a regular crystal as a perfect pattern of squares,” says Krogstad. “Introducing random palladium atoms changes the pattern a little bit because of its randomness, but it doesn’t completely destroy it either. This structure can tolerate some randomness.”
This discovery answers the long-standing question of whether a disordered CDW sample loses its crystalline order when cooled and splits into small patches or becomes Bragg glass. Insights into the structure and behavior of Bragg glasses have the potential to help design useful materials in the future.
Research paper “Bragg glass signature of PD”XErte3 “By X-ray diffraction temperature clustering” Published in Nature Physics. This research was supported by the Department of Energy, Office of Basic Energy Sciences, Division of Materials Science and Engineering. In addition to Krogstad and Osborn, authors include Krishnanand Malaiya, Joshua Strakuadin, Maya D. Bachman, Anisha G. Singh, Stephen Rosencrantz, Ian R. Fisher, and Una Kim. will appear.
About Advanced Photon Source
The U.S. Department of Energy's Office of Science's Advanced Photon Source (APS) at Argonne National Laboratory is one of the most productive X-ray source facilities in the world. APS provides high-brightness x-ray beams to a diverse community of researchers in materials science, chemistry, condensed matter physics, life sciences, environmental sciences, and applied research. These X-rays are ideal for probing materials and biological structures. Distribution of elements. Chemistry, magnetism, electronic states. And there is a wide range of technologically important engineered systems, from batteries to fuel injector sprays, all of which are the foundation of our nation's economic, technological, and physical well-being. Each year, more than 5,000 researchers use his APS to produce his more than 2,000 publications detailing their seminal discoveries, and more than any other user of his X-ray Source Research Facility. has also elucidated the structure of important biological proteins. APS scientists and engineers innovate technologies that are central to advances in accelerator and light source operations. This includes insertion devices that produce ultra-bright X-rays that researchers value, lenses that focus the X-rays down to a few nanometers, and equipment that maximizes the way the X-rays interact with the samples being studied. , and software that collects and performs collections. Manage large amounts of data from discovery research at APS.
This research used resources from the Advanced Photon Source, a U.S. Department of Energy Office of Science User Facility operated by Argonne National Laboratory for the DOE Office of Science under contract number DE-AC02-06CH11357.
Argonne National Laboratory Seeks solutions to pressing national problems in science and technology. The nation's first national research laboratory, Argonne conducts cutting-edge basic and applied scientific research in virtually every scientific field. Argonne researchers work closely with researchers at hundreds of companies, universities, and federal, state, and local agencies to solve specific problems, advance America's scientific leadership, and make the nation better. We provide support to prepare for a better future. With employees from more than 60 countries, Argonne is managed by his UChicago Argonne, LLC of the U.S. Department of Energy's Office of Science.
U.S. Department of Energy Office of Science is the 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 https:// ener gy .gov/s science.
