Scientists See Atomic Distortions In Crystals | Chemical & Engineering News
Volume 93 Issue 8 | p. 35 | Concentrates
Issue Date: February 23, 2015

Scientists See Atomic Distortions In Crystals

Electron microscopy technique allows researchers to directly visualize crystals with unprecedented precision
Department: Science & Technology
News Channels: Materials SCENE, Analytical SCENE
Keywords: scanning transmission electron microscopy, STEM, crystal, solid-state
[+]Enlarge
Black electron density clouds show “covalent cages” in crosssections of a lanthanum strontium aluminum tantalum oxide crystal. The cages are the three-dimensional translucent structures below and to the left of the crosssections.
Credit: Appl. Phys. Lett.
Oxygen bonds hold Al and Ta in place in a metal oxide crystal.
 
Black electron density clouds show “covalent cages” in crosssections of a lanthanum strontium aluminum tantalum oxide crystal. The cages are the three-dimensional translucent structures below and to the left of the crosssections.
Credit: Appl. Phys. Lett.

How atoms are organized with respect to one another is critical to the performance of solids such as ceramics and alloys. Electron microscopy allows researchers to observe solid-state materials with angstrom-scale precision, but subtle, inadvertent sample motions inevitably obscure important structural details. Materials scientists led by James M. LeBeau at North Carolina State University have shown that revolving scanning transmission electron microscopy can reveal crystal lattice distortions more precisely, at the picometer scale (Appl. Phys. Lett. 2015, DOI:10.1063/1.4908124). By rotating the scan direction of their microscope’s electron beam, the researchers corrected for sample drift and directly visualized the location of individual atoms in an LSAT crystal—a metal oxide containing lanthanum, strontium, aluminum, and tantalum. The researchers found that Al and Ta atoms in their sample were effectively caged in place by covalent bonds with neighboring oxygen atoms, and La and Sr atoms had more freedom to shift their positions.

 
Chemical & Engineering News
ISSN 0009-2347
Copyright © American Chemical Society

Leave A Comment

*Required to comment