Argonne National Laboratory

Research Highlight | Materials Science

Bragg coherent diffractive imaging of single-grain defect dynamics
In a study published in Science, researchers pave the way for understanding polycrystalline material response under external stimuli and engineering particular functions.
Grain boundary and dislocation movement in a single gold grain during heating
Grain boundary and dislocation movement in a single gold grain during heating. (A) A 3D rendering of the reconstructed grain image; (B) cross-section view [cross-section location shown by the black dashed line in (A)] of the reconstructed Bragg electron density; and (C) cross-section view of the reconstructed displacement field for the as-synthesized state. The black arrow is the [111] scattering vector that is normal to a {111} facet. The white arrows show a low-amplitude region in the Bragg electron density and a corresponding discontinuity in the displacement field, which is consistent with a dislocation. (D to F) The same as in (A) to (C) but at 400°C. Grain growth, particularly near the dislocation, has occurred. The dislocation is absent.

Scientific Achievement

Bragg coherent diffraction imaging (BCDI) reveals internal strain, defect annihilation, and growth of single grains in a polycrystalline Au film during annealing.

Significance and Impact

This work shows that BCDI can be broadly used to understand the links between grains, their defects, and the properties of polycrystalline materials.

Research Details

  • BCDI was performed during annealing of a polycrystalline Au film to observe the evolution of the shape of individual grains and their internal strain fields with 10-nanometer spatial and subangstrom displacement field resolution
  • Dislocation loops terminating at grain boundaries were identified, and their evolution followed as the sample was heated in steps
  • We observed a dislocation loop annihilating into a grain boundary at 400 C, locally enhancing grain growth
  • Dynamics of coherent twin boundaries were also observed
  • Extension of BCDI imaging from nanoparticles to polycrystalline films opens a new window on an important class of materials

DOI: 10.1126/science.aam6168

Download the highlight

Argonne National Laboratory seeks solutions to pressing national problems in science and technology. The nation’s first national laboratory, Argonne conducts leading-edge basic and applied scientific research in virtually every scientific discipline. Argonne researchers work closely with researchers from hundreds of companies, universities, and federal, state and municipal agencies to help them solve their specific problems, advance America’s scientific leadership and prepare the nation for a better future. With employees from more than 60 nations, Argonne is managed by UChicago Argonne, LLC for the U.S. Department of Energy’s Office of Science.

The U.S. Department of Energy’s Office of Science is the single largest supporter of basic research in the physical sciences in the United States and is working to address some of the most pressing challenges of our time. For more information, visit https://​ener​gy​.gov/​s​c​ience.