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Lattice anharmonicity in defect-free Pd nanowhiskers
Lisa Y Chen1, Gunther Richter, John P Sullivan
1Department of Materials Science and Engineering, University of Pennsylvania, Philadelphia, 19104, USA.
Physical Review Letters
|September 26, 2012
Summary
We studied palladium (Pd) nanowhiskers to understand how their size affects elastic properties. Smaller nanowhiskers show unique nonlinear elasticity due to surface stress, impacting mechanical behavior.
Area of Science:
- Materials Science
- Nanotechnology
- Solid Mechanics
Background:
- Bulk materials exhibit predictable elastic behavior.
- Surface stresses become significant in nanoscale materials.
- Understanding size effects is crucial for designing nanodevices.
Purpose of the Study:
- Investigate anharmonic elasticity in palladium (Pd) nanowhiskers.
- Quantify size-dependent elastic behavior at the nanoscale.
- Determine the influence of surface stress on material nonlinearity.
Main Methods:
- Systematic nanoscale tensile testing of near defect-free Pd nanowhiskers.
- Measurement of size-dependent Young's modulus and nonlinear elasticity.
- Calculation of second- and third-order elastic moduli and material nonlinearity parameters (δ).
Main Results:
- Observed deviations from bulk elastic behavior in nanowhiskers down to ~30 nm diameter.
- Measured size-dependent Young's modulus and nonlinear elasticity above ~1% strain.
- Attributed phenomena to higher-order elasticity and surface stress effects.
Conclusions:
- Nanoscale Pd exhibits size-dependent elasticity and nonlinear behavior.
- Surface stresses play a critical role in the mechanical properties of small volumes.
- Length scale significantly influences both elastic and plastic mechanical behavior.
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