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Viscoelastic properties of crystals
Stephen R Williams1, Denis J Evans
1Research School of Chemistry, The Australian National University, Canberra, Australian Capital Territory 0200, Australia. swilliams@rsc.anu.edu.au
The Journal of Chemical Physics
|July 17, 2009
Summary
Fluids have zero shear modulus, unlike crystals. Contrary to common belief, crystals do not have infinite shear viscosity but less than glass.
Area of Science:
- Materials Science
- Rheology
- Condensed Matter Physics
Background:
- Distinguishing between fluids and crystals is crucial in materials science.
- Shear modulus and shear viscosity are key rheological properties.
- Previous assumptions suggested crystals possess infinite zero-frequency shear viscosity.
Purpose of the Study:
- To investigate the differentiation between fluids and crystals based on rheological properties.
- To clarify the values of zero-frequency shear modulus and limiting zero-frequency shear viscosity in fluids and crystals.
Main Methods:
- Theoretical analysis of rheological properties.
- Comparison of shear modulus and viscosity values for fluids, crystals, and glasses.
Main Results:
- Fluids exhibit a zero shear modulus, while crystals do not.
- Crystals do not possess infinite limiting zero-frequency shear viscosity.
- Crystal viscosity is higher than the parent liquid but lower than the corresponding glass.
Conclusions:
- The zero-frequency shear modulus effectively differentiates fluids from crystals.
- The limiting zero-frequency shear viscosity is not an indicator for distinguishing crystals from fluids.
- Viscosity measurements provide insights into the transition from liquid to crystal to glass states.
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