ADVANCED MATERIALS & PROCESSES | JULY/AUGUST 2023 12 NANOTECHNOLOGY SELF-ASSEMBLING CRYSTAL STRUCTURES Scientists at Cornell University, Ithaca, N.Y., used a targeted computational approach to find more than 20 new self-assembled crystal structures. The team conducted a targeted search for previously unknown low-coordinated assemblies within a vast parameter space spanned by particles interacting via isotropic pair potentials. Low particle coordination is a structural characteristic key to the functional properties of many technologically important materials, including metal-organic frameworks, clathrates, and zeolites, as well as photonic crystals such as diamond. The researchers developed a new functional form for particle interactions in which all features can be tuned independently. By systematically changing pairs of parameters in simulation, the researchers were able to control various features of the particles’ interaction landscape. A wealth of complexity and symmetry is apparent within these crystal structures. The work demonstrates that complicated structures can develop from simple interactions and adds new theoretical structures for others working in the field. The team’s flexible and intuitive interaction potential design serves as an important step toward determining the characteristics of particle interactions that lead to certain structural properties, useful for establishing synthetic rules to make target structures. The findings suggest that there are potentially limitless new and exotic material configurations possible through controlled selfassembly. “This is the first time that we’re quantifying the relationship of this isotropic pair potential with the crystal structures that result,” says lead researcher Julia Dshemuchadse. “These new crystal structures can now serve as design targets for researchers who actually make nanoparticles and colloids.” cornell.edu. TRANSFORMABLE NANOSCALE DEVICES A finding by University of California, Irvine, physicists revealed the potential for nanoscale devices to transform into many different shapes and sizes while Conceptual image showcasing several interaction potential shapes, represented by stems, that lead to the self-assembly of new low-coordinated crystal structures, represented by flowers. existing in solid states. The discovery of this new property could fundamentally change the nature of electronic devices as well as the way scientists research atomic-scale quantum materials. Researchers found that for a particular set of materials, they could make modifiable nanoscale electronic devices that aren’t stuck together. The physicists explain that the modular parts allow for modification of size and shape after a device has been made. Until now, this was considered by scientists to be impossible. What they saw specifically was that tiny nanoscale gold wires could slide with very low friction on top of van der Waals materials. Taking advantage of these slippery interfaces, they made electronic devices comprised of single-atom thick sheets of graphene attached to gold wires that can be transformed into a variety of different configurations. The team expects their work could usher in a new era of quantum science research. uci.edu. Triangular holes make this material more likely to crack from le to right. Courtesy of N.R. Brodnik et al./Phys. Rev. Lett. Using a new microscopy technique that employs blue light to measure electrons in semiconductors and other nanoscale materials, a research team at Brown University, Providence, R.I., is at the forefront of developing new ways to study these components. The findings are a first in nanoscale imaging and offer a solution to a persistent problem that has limited the study of key phenomena in a variety of materials that could lead to more energyefficient electronics. brown.edu. BRIEF The golden parts of the device depicted in this graphic are transformable. Courtesy of Yuhui Yang/UC.
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