Peering At Atoms With New Techniques

 Microscopy  

Scientists at the University of California Los Angeles have found a way to create stunningly detailed 3D reconstructing of platinum nanoparticles at an atomic scale. These are being used to study tiny structural irregularities called dislocations.

Scientists at the University of California Los Angeles have found a way to create stunningly detailed 3D reconstructing of platinum nanoparticles at an atomic scale. These are being used to study tiny structural irregularities called dislocations.

The study was published recently in the journal Nature.

Dislocations and their interactions strongly influence many material properties, ranging from the strength of metals and alloys to the efficiency of light-emitting diodes and laser diodes.

Several experimental methods can be used to visualize dislocations. Transmission electron microscopy (TEM) has long been used to image dislocations in materials, and high-resolution electron microscopy can reveal dislocation core structures in high detail, particularly in annular dark-field mode.

A TEM image, however, represents a two-dimensional projection of a three-dimensional (3D) object (although stereo TEM provides limited information about 3D dislocations). 

X-ray tomography can image dislocations in three dimensions, but with reduced resolution. Using weak-beam dark-field TEM and scanning TEM, electron tomography, the researchers imaged 3D dislocations at a resolution of about five nanometres. 

The scientists report 3D imaging of dislocations in materials at atomic resolution by electron tomography. 

Using their techniques, the researchers observed nearly all the atoms in a multiply twinned platinum nanoparticle. 

They observed atomic steps at 3D twin boundaries and imaged the 3D core structure of edge and screw dislocations at atomic resolution. These dislocations and the atomic steps at the twin boundaries, which appear to be stress-relief mechanisms, are not visible in conventional two-dimensional projections. 

The ability to image 3D disordered structures such as dislocations at atomic resolution is expected to find applications in materials science, nanoscience, solid-state physics and chemistry.


SOURCE  Nature

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