In each dimensional plane, they found that two pairs of parallel ultrasound transducers suffice to arrange particles in a periodic structure.īut what would happen if they had one more pair of transducers? To find out, Raeymaekers and graduate student Milo Prisbrey (now at Los Alamos National Laboratory) provided the experimental instruments, and mathematics professor Elena Cherkaev provided experience with the mathematical theory of quasicrystals. They weren’t initially looking to create quasiperiodic materials-in fact, their first theoretical experiments, led by mathematics doctoral student China Mauck, were focused on periodic materials and what patterns of particles might be possible to achieve by using ultrasound waves. Since 2012, Guevara and Bart Raeymaekers, associate professor of mechanical engineering, have been collaborating on designing materials with custom-designed structures at the microscale. The discovery of quasiperiodic structures in some metal alloys by materials scientist Dan Schechtman earned a 2011 Nobel Prize in Chemistry and opened up the study of quasicrystals. But you can’t copy and paste this pattern. At first glance, the geometric diamond-shaped tiles appear to be in a regular pattern. One example is the pattern called Penrose tiling.
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Download Full-Res Imageīut a quasiperiodic structure is deceiving. PHOTO CREDIT: Courtesy of Fernando Guevara VasquezĪ quasiperiodic two-dimensional pattern. You could copy and paste the lattice from one part of the crystal and find a match in any other part. At the atomic level, it is a grid-like lattice of sodium and chloride atoms. Such “periodic” structures, with patterns that do repeat, naturally occur in crystals.
You can take a two-by-two square of two black tiles and two white (or red) tiles and copy and paste to obtain the whole checkerboard. “They have been shown to be stiffer than similar periodic or disordered materials. They can also conduct electricity, or scatter waves in ways that are different from crystals.” Non-pattern patterns “Quasicrystals are interesting to study because they have properties that crystals do not have,” says Fernando Guevara Vasquez, associate professor of mathematics. The research is published in Physical Review Letters. The results, they say, could result in materials called “quasicrystals” with custom magnetic or electrical properties. Mathematicians and engineers at the University of Utah have teamed up to show how ultrasound waves can organize carbon particles in water into a sort of pattern that never repeats.
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