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Three-dimensional imaging of microstructure in Au nanocrystals
G J Williams1, M A Pfeifer, I A Vartanyants
1Department of Physics, University of Illinois, Urbana, Illinois 61810, USA.
Physical Review Letters
|June 6, 2003
Summary
Coherent X-ray diffraction imaging reveals internal twinning in gold nanocrystals. These 50 nm bands, oriented [111], likely form during high-temperature dynamic recrystallization.
Area of Science:
- Materials Science
- Crystallography
- Nanotechnology
Background:
- X-ray diffraction (XRD) is a powerful technique for analyzing crystal structures.
- Coherent X-ray diffraction (CXD) enables imaging of nanoscale materials.
- Understanding nanocrystal formation mechanisms is crucial for materials development.
Purpose of the Study:
- To visualize the internal structure of gold (Au) nanocrystals.
- To investigate the origin of internal contrast bands observed in Au nanocrystals.
- To explore the role of dynamic recrystallization in nanocrystal formation.
Main Methods:
- Utilized coherent X-ray diffraction (CXD) with a coherent beam.
- Employed oversampling techniques to phase the continuous diffraction pattern.
- Reconstructed three-dimensional (3D) images of the interior of Au nanocrystals.
Main Results:
- Obtained 3D images revealing internal structures within Au nanocrystals.
- Identified 50 nm wide bands of contrast with [111] crystallographic orientation.
- These bands are hypothesized to result from internal twinning.
Conclusions:
- Internal twinning, likely caused by dynamic recrystallization, influences Au nanocrystal structure during high-temperature formation.
- CXD is effective for high-resolution 3D imaging of nanocrystal interiors.
- The findings provide insights into the growth mechanisms of metallic nanocrystals.