Glasses have disordered arrangements of atoms without the repeating patterns that crystals have. However, there are small-scale patterns of atoms that touch each other that strongly affect the energy of the glass, how the atoms move when they get hot, and other properties like strength and response to an electric field. Unfortunately, there are many possible patterns and many slight variations of each one, so studying them is like sorting the grains of sand on a beach by size and color by hand–it’s an impossible task. Wisconsin MRSEC IRG 1 uses machine learning to sort the sand. They have developed algorithms to find small-scale atomic patterns in large simulations of glasses and link them to the glass’ energy. Ongoing studies have connected patterns to atomic motions, which provides a path to simulations of glasses over long times and low temperatures that are currently impossible.
Center Highlights
(2021) Controlling Waves with 3D Printed Materials
Materials with a repetitive pattern the same size as the wavelength of a wave can be used to control the wave, causing it to bend, perfectly reflect or transmit, or even turn around corners. Where different patterns meet, even more exotic behavior occurs, including making highways for light or sound that only travel in one direction or where the waves cannot be dissipated. Synthesizing such materials is a major challenge, which Wisconsin MRSEC researchers have met by adapting a family of 3D printing techniques.
(2020) Energy Transfer Inside of a Topological Photonic Materials
The Wisconsin MRSEC has shown that molecules inside in a type of topological photonic material called a Weyl crystal can exchange energy over much larger distances. The intricate twisting structure of the material uses light to connect one molecule to others much farther away. Developing photonic Weyl crystals may contribute to more efficient LEDs and solar cells and improve molecular sensors.
(2020) Sparking Student Interest: Renewable Energy Devices in the Classroom
The Wisconsin MRSEC has developed a simple, inexpensive way for K-12 students to build a sustainable energy device using familiar, everyday materials including aluminum foil, a plastic egg, clear tape, and a bouncy ball. The device, called a triboelectric nanogenerator, converts the often-wasted energy of motion into useful electrical energy.
(2020) Solid-Phase Crystallization Produces Oxide Buffer Layers Lattice-Matched to Semiconductors
Engineers currently lack good substrate materials on which to grow thin films of materials like GaN with few defects. These layers are needed in applications like high-power transistors and solid-state lighting. Available bulk crystals have the wrong crystal structure or the wrong distance between the atoms. The Wisconsin MRSEC has developed a buffer layer material and related synthesis method that promises to alleviate the substrate problem.
(2020) Research Endeavors, Cross-Cultural Experiences, and Educational Activities
The Wisconsin MRSEC Research Experience for Teachers (RET) program is a cross-cultural collaboration with the University of Puerto Rico-Mayagüez (UPRM). The RET program provides science teachers from Wisconsin and Puerto Rico an authentic research and cultural literacy professional development experience. The program culminates with an in-person capstone week where the RETs from both sites share the research-inspired classroom activities they have developed and learn from one another about teaching in a different cultural and geographic environment. The teachers learn about the area and culture that is unique to the site hosting the capstone.
(2020) Solid-phase Epitaxy Produces Magnetic Oxides with Novel Magnetic Properties
The Wisconsin MRSEC has created thin films of a fascinating magnetic material, Pr2Ir2O7, in which the magnetic moments are frustrated: No matter how they are arranged, some of the moments are always fighting to change their direction, like two bar magnets with their north poles shoved together. Frustration creates a rich landscape for discovery and manipulation of new magnetic effects and of electronic phenomena linked to magnetism.
(2020) Order From Disorder: Molecular Packing in Glasses
Using physical vapor deposition, researchers produced glassy films that are smooth and uniform, but which also have the molecules aligned with one another and organized in layers. This added structure could make the glass more efficient for conductors and expand the range of materials that can be used in future organic electronics. The colorful images in the figure show measurements using synchrotron x-rays that contrast the disordered starting material and the ordered glass.
(2020) Why Sound Waves Travel So Far Unimpeded in Glasses at Low Temperatures
IRG 1 showed how the atoms around the defects can restrict their ability to jump between configurations and how defects can talk to each other via sound waves. Both phenomena keep the defects from interfering with sound waves allowing the waves to travel long distances.
(2020) Wisconsin MRSEC Excellence in Open Science Prize
The Wisconsin MRSEC is committed to being a leader in Open Science, which shares data in digital forms following FAIR1 principles. As part of these efforts the Center has developed a new web site, a best practices guide, and held informational events. This year the Center launched the first Wisconsin MRSEC Excellence in Open Science Prize. The winner was graduate student Bradley Dallin2 for his work on molecules interacting with water, with potential applications from understanding human blood to protein folding diseases like Alzheimer’s. Bradley shared his results in papers, but also shared all his simulations and tools in an open accessible format for the community, increasing the impact of his work.