AMP_06_September_2021

A D V A N C E D M A T E R I A L S & P R O C E S S E S | S E P T E M B E R 2 0 2 1 9 team of international collaborators led by Lawrence Livermore Nation- al Laboratory (LLNL), Calif., has demon- strated the first-ever “defect micro- scope” that can track how populations of defects deep inside macroscopic materials move collectively. The re- search shows a classical example of a dislocation boundary, then demon- strates how these same defects move exotically just at the edge of melting temperatures. The teamused time-resolved dark- field x-raymicroscopy (DFXM) to directly visualize how dislocations move and interact over hundreds of micrometers deep inside bulk aluminum. With real- time movies, they showed the ther- mally activatedmotion and interactions of dislocations that comprise a bound- ary and show how weakened binding forces destabilize the structure at 99% of the melting temperature. “By visualizing and quantifying thermally activated dynamics that were previously limited to theory, we demon- strate a newclass of bulkmeasurements TESTING | CHARACTERIZATION MORE ACCURATE MEASUREMENTS A new measurement method developed by researchers at the National Institute of Standards and Technology (NIST), Gaithersburg, Md., enables conventional microscopes to accurately measure the positions of points of light on a sample in 3D and precisely locate the positions of objects. The technique relies on a care- ful analysis of images of fluorescent particles that the researchers deposited on flat silicon wafers for calibration of their microscope. Due to lens aberra- tions, as the microscope moved up and down by specific increments along the vertical axis, the images appeared lop- sided, and the shapes and positions of the particles appeared to change. The researchers found that the aberrations can produce large distortions in images even if the microscope moves just a few microme- ters in any direction. The analysis enabled the researchers to model exactly how the lens aber- rations altered the appear- ance and apparent location of the fluorescent particles with changes in the verti- cal position. By carefully calibrating the changing appearance and appar- ent location of a particle to its vertical position, the team succeeded in using the microscope to accu- rately measure positions in all three dimensions. Using the latent information provided by lens aberrations comple- ments the less accessible methods that microscopists currently employ to make 3D measurements. The research- ers say microscopy laboratories could easily implement the new technique. “The user just needs a standard sample tomeasure their effects and a calibration to use the resulting data,” they add . nist.gov. DEFECT MICROSCOPE Connecting a bulk material’s microscopic defects to its macro- scopic properties is an age-old problem inma- terials science. Now, a Dark-field x-ray microscopy views defects deep inside millimeter- thick crystals. Courtesy of LLNL. Triangular holes make this material more likely to crack from left to right. Courtesy of N.R. Brodnik et al./ Phys. Rev. Lett. NSL Analytical Services Inc., Cleveland, recently expanded its battery materials testing capabilities. NSL’s ISO 17025 accredited chemical and physical analysis services test materials in nearly all types of battery systems, from lead acid to lithium-ion. Testing includes chemical analysis of bulk and trace species, moisture and thermal analysis, microsco- py, elemental mapping, and more. nslanalytical.com . BRIEF Left, top to bottom: Images of fluorescent particles that are above, at, and below the vertical position of best focus of a microscope. Right: Tiny rotating gear collects information from fluorescent particles. Courtesy of NIST.

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