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Two-Dimensional Melting of Colloidal Hard Spheres.
Alice L Thorneywork1, Joshua L Abbott1, Dirk G A L Aarts1
1Department of Chemistry, Physical and Theoretical Chemistry Laboratory, University of Oxford, South Parks Road, Oxford OX1 3QZ, United Kingdom.
Physical Review Letters
|April 29, 2017
Summary
This study investigates the melting of colloidal hard spheres, revealing a first-order liquid-hexatic transition and a continuous hexatic-crystal transition. Researchers experimentally established the complete phase behavior of hard disks.
Area of Science:
- Condensed matter physics
- Colloidal science
- Statistical mechanics
Background:
- Understanding phase transitions in two-dimensional systems is crucial for materials science.
- Colloidal hard spheres provide a model system for studying fundamental physical phenomena.
- Previous research has explored various aspects of hard sphere systems, but a complete experimental phase diagram for quasi-two-dimensional systems remains an active area of investigation.
Purpose of the Study:
- To experimentally determine the phase behavior of quasi-two-dimensional colloidal hard spheres.
- To precisely characterize the nature of the liquid-hexatic and hexatic-crystal transitions.
- To measure the liquid-hexatic coexistence gap and establish the full phase diagram.
Main Methods:
- Utilizing a tilted monolayer of colloidal hard spheres in sedimentation-diffusion equilibrium.
- Measuring the equation of state from particle density profiles.
- Employing time-dependent and height-resolved correlation functions to identify distinct phases.
- Directly measuring the width of the liquid-hexatic coexistence gap via interface fluctuation analysis.
Main Results:
- The liquid-hexatic transition was identified as first order.
- The hexatic-crystal transition was determined to be continuous.
- The width of the liquid-hexatic coexistence gap was experimentally quantified.
- The complete phase behavior of hard disks in a quasi-two-dimensional system was established.
Conclusions:
- The study provides a comprehensive experimental phase diagram for quasi-two-dimensional hard disks.
- The findings contribute to a deeper understanding of phase transitions in two-dimensional systems.
- This work validates theoretical predictions and offers insights for designing colloidal materials.
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