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Updated: Jun 6, 2025
06:26
Orientational Transition in a Liquid Crystal Triggered by the Thermodynamic Growth of Interfacial Wetting Sheets
Published on: May 15, 2017
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Nucleation kinetics and virtual melting in shear-induced structural transitions
Wei Li1, Yi Peng2,3, Tim Still4
1Department of Physics, Hong Kong University of Science and Technology, Clear Water Bay, Hong Kong Special Administrative Region of China, People's Republic of China.
Reports on Progress in Physics. Physical Society (Great Britain)
|December 3, 2024
Summary
Shear strain transforms square colloidal crystals into triangular ones. A liquid layer forms around growing triangular nuclei, a phenomenon termed "virtual melting," observed experimentally for the first time.
Area of Science:
- Materials Science
- Condensed Matter Physics
- Crystallography
Background:
- Shear deformations can alter crystal structures, but the underlying microscopic kinetics are challenging to study experimentally.
- Understanding shear-induced phase transitions is crucial for materials engineering and fundamental physics.
Purpose of the Study:
- To investigate shear-induced structural transitions in colloidal crystals.
- To observe the kinetics of square (◻) to triangular (△) lattice transformations at the single-particle level.
- To experimentally validate the phenomenon of
- virtual melting
- at crystalline interfaces.
Main Methods:
- Utilized thin-film colloidal crystals subjected to oscillatory shear strain.
- Employed single-particle resolution microscopy to observe structural changes within the bulk crystal.
- Analyzed the formation and dynamics of triangular lattice nuclei during the transition.
Main Results:
- Observed direct shear-induced structural transitions from square to triangular lattices.
- Discovered that triangular lattice nuclei are surrounded by a liquid layer during growth (0.1⩽γm<0.4).
- Demonstrated that the liquid layer thickness is proportional to the applied shear, consistent with the Lindemann melting criterion.
Conclusions:
- Provided the first experimental observation of "virtual melting" at crystalline interfaces during shear-induced transitions.
- Established a link between shear strain, liquid layer formation, and the Lindemann melting criterion.
- Offered new insights into the kinetics of shear-induced structural transformations in crystalline materials.
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