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Pseudoelasticity at Large Strains in Au Nanocrystals
X Wendy Gu1,2, Lindsey A Hanson3,4, Carissa N Eisler4
1Department of Chemistry, University of California, Berkeley, Berkeley, California 94720, USA.
Physical Review Letters
|August 18, 2018
Summary
Gold nanocrystals exhibit pseudoelasticity, recovering their shape after significant deformation. This finding expands the understanding of nanoscale material properties and potential defect trapping during recovery.
Area of Science:
- Materials Science
- Nanotechnology
- Solid State Physics
Background:
- Pseudoelasticity in metals is typically linked to phase transformations.
- Recent studies observed pseudoelasticity in sub-10 nm silver (Ag) nanocrystals.
- Understanding pseudoelasticity in different metals and sizes remains unclear.
Purpose of the Study:
- To investigate pseudoelasticity in gold (Au) nanocrystals of varying sizes.
- To explore the mechanistic understanding of nanoscale pseudoelasticity.
- To determine if crystalline defects are trapped after deformation.
Main Methods:
- Compression of colloidal Au nanocrystals using a diamond anvil cell.
- Quasihydrostatic and nonhydrostatic pressure conditions were applied.
- Optical spectroscopy, transmission electron microscopy, and electrodynamic theory modeling were used.
Main Results:
- 3.9 nm Au nanocrystals showed pseudoelastic shape recovery after up to 20% strain.
- This strain is equivalent to an aspect ratio of 2.
- Absorbance efficiency did not recover, suggesting trapped crystalline defects.
Conclusions:
- Pseudoelasticity is present in Au nanocrystals, similar to Ag.
- Nanoscale pseudoelasticity involves complex atomic motion at surfaces.
- Defect trapping may occur during the recovery process in deformed nanocrystals.
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