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Published on: May 10, 2021
Premelting at defects within bulk colloidal crystals
A M Alsayed1, M F Islam, J Zhang
1Department of Physics and Astronomy, University of Pennsylvania, 209 South 33rd Street, Philadelphia, PA 19104-6396, USA.
Science (New York, N.Y.)
|July 5, 2005
Summary
Researchers observed premelting, a precursor to melting, within colloidal crystals at defects like grain boundaries and dislocations. This finding expands our understanding of crystal behavior and the role of interfacial free energy.
Area of Science:
- Materials Science
- Condensed Matter Physics
- Colloid Science
Background:
- Premelting is the localized loss of crystalline order below the bulk melting point.
- Previously, premelting was only observed at crystal surfaces, not within the bulk.
- Understanding premelting is key to comprehending material behavior near phase transitions.
Purpose of the Study:
- To investigate the phenomenon of premelting within the bulk of colloidal crystals.
- To identify the locations and conditions under which premelting occurs internally.
- To explore the relationship between defects and premelting in colloidal systems.
Main Methods:
- Utilized real-time video microscopy to observe colloidal crystals.
- Employed particle tracking to analyze crystalline order and disorder.
- Synthesized equilibrium close-packed, three-dimensional colloidal structures from microgel spheres.
Main Results:
- Observed premelting at grain boundaries and dislocations within bulk colloidal crystals.
- Quantified increased disorder near defects, dependent on defect type and distance.
- Demonstrated that particle volume fraction influences the extent of premelting.
Conclusions:
- Premelting occurs within colloidal crystals at internal defects, not just surfaces.
- Interfacial free energy is identified as a critical parameter governing premelting.
- Findings have implications for both colloidal and atomic-scale crystal premelting phenomena.
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