8 ADVANCED MATERIALS & PROCESSES | MARCH 2024 VISUALIZING NANOSCALE FORCES OF LIGHT At the University of Illinois Urbana- Champaign’s Beckman Institute for Advanced Science and Technology and the Nick Holonyak Micro and Nanotechnology Laboratory, researchers developed a groundbreaking microscope that visualizes the invisible forces exerted by light at the nanoscale. Using their newly created tool—Decoupled Optical Force Nanoscopy (Dofn)— the researchers explored the mechanics of how light can generate minute forces upon nanoscale specimens. “Dofn acts as a bridge over previous technological gaps, giving us the ability to explore and quantify how light-induced forces manifest as both pressure and heat at the nanoscale,” says researcher Hanwei Wang. These observations mark a paradigm shift in scientists’ ability to understand and TESTING | CHARACTERIZATION MAPPING ATOMIC COORDINATES IN 3D For the first time, researchers mapped the 3D atomic coordinates of medium- and high-entropy alloys. Led by University of California, Los Angeles (UCLA) scientists, the research team used an advanced imaging technique to gain novel views of the alloys’ structure and characteristics. In another scientific first for any material, the researchers correlated the mixture of elements with structural defects. The researchers focused on twin boundary formation, which is understood to be a key factor in medium- and high-entropy alloys’ unique combination of toughness and flexibility. Twinning happens when strain causes one section of a crystal matrix to bend diagonally while the atoms around it remain in their original configuration, forming mirror images on either side of the boundary. The team used an array of metals to make six medium-entropy alloy nano- particles, combining nickel, palladium, and platinum. Four nanoparticles of a high-entropy alloy combined cobalt, nickel, ruthenium, rhodium, palladium, silver, iridium, and platinum. The scientists liquified the metal at over 2000°F for five-hundredths of a second, then cooled it down in less than one-tenth that time. The shock of the process induced twin boundaries in six of the 10 nanoparticles—four of those each had a pair of twins. To identify the defects, the researchers developed a new technique called atomic electron tomography, and then mapped each atom in the medium-entropy alloy nanoparticles. The researchers observed that the more atoms of different elements are mixed, the more likely the alloy’s structure will change in a way that contributes to matching toughness with flexibility. The findings could inform the design of medium- and high- entropy alloys with added durability and even unlock potential properties currently unseen in steel and other conventional alloys by engineering the mixture of certain elements. ucla.edu. Triangular holes make this material more likely to crack from left to right. Courtesy of N.R. Brodnik et al./Phys. Rev. Lett. Oxford Instruments plc, U.K., acquired First Light Imaging SAS, France, a manufacturer of high-speed, low-noise scientific cameras for infrared and visible imaging, with applications in astronomy and the life sciences. oxinst.com. Bruker, Billerica, Mass., acquired Nion, Kirkland, Wash., a manufacturer of advanced scanning transmission electron microscopes (STEM). Nion was the first to introduce aberration correction for STEM instruments with ultra-high stability for the highest resolution images. bruker.com. BRIEFS The study’s authors from Beckman Institute include, from left: Catherine Murphy, Hanwei Wang, Yang Zhao, and Yun-Sheng Chen. Atomic map of a high-entropy alloy nanoparticle shows different categories of elements in red, blue, and green, and twinning boundaries in yellow. Courtesy of Miao Lab/UCLA.
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