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Updated: Jul 28, 2025
09:13
Characterization of Ultra-fine Grained and Nanocrystalline Materials Using Transmission Kikuchi Diffraction
Published on: April 1, 2017
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Unveiling the complexity of nanodiamond structures.
Qi Zheng1,2,3, Xian Shi4, Jinyang Jiang2,3
1Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720.
Summary
Small nanodiamonds exhibit unusual electron diffraction patterns due to their size and defects. These findings clarify the complex structures of nanodiamonds and potential new forms.
Area of Science:
- Materials Science
- Nanotechnology
- Crystallography
Background:
- Understanding nanodiamond structures is crucial but challenging due to their complexity and polymorphic forms.
- Distinguishing between cubic diamond and potential new diamond structures has been difficult.
Purpose of the Study:
- To investigate the impact of small sizes and defects on cubic diamond nanostructures.
- To resolve controversies surrounding nanodiamond polymorphic forms.
Main Methods:
- Transmission electron microscopy with high-resolution imaging.
- Electron diffraction and multislice simulations.
- Analysis of surface distortions, internal dislocations, and grain boundaries.
Main Results:
- Common cubic diamond nanoparticles show (200) forbidden reflections in electron diffraction, mimicking new diamond (n-diamond).
- Cubic nanodiamonds <5 nm exhibit d-spacing at 1.78 Å (200) forbidden reflections, intensifying with decreasing size.
- Defects like surface distortions and dislocations also cause visible (200) forbidden reflections.
Conclusions:
- Small size and defects significantly influence nanodiamond structures.
- The presence of (200) forbidden reflections is linked to size and defects, not necessarily new diamond polymorphs.
- Findings offer insights into nanoscale diamond complexity and the discovery of novel diamond structures.
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