Related Experiment Video
Updated: Apr 4, 2026
06:26
Orientational Transition in a Liquid Crystal Triggered by the Thermodynamic Growth of Interfacial Wetting Sheets
Published on: May 15, 2017
7.7K
Electric-Field-Induced Reversible Phase Transitions in Two-Dimensional Colloidal Crystals
Kelsey A Collins1, Xiao Zhong1, Pengcheng Song1
1Molecular Design Institute and Department of Chemistry, New York University , New York, New York, 10003, United States.
Langmuir : the ACS Journal of Surfaces and Colloids
|September 8, 2015
Summary
Two-dimensional colloidal crystals in electric fields show reversible phase transitions. Particle arrangement changes with electric field strength and number, enabling a tunable phase diagram.
Area of Science:
- Colloidal science
- Soft matter physics
- Materials science
Background:
- Two-dimensional colloidal crystals exhibit complex behaviors under external stimuli.
- Dielectrophoretic traps provide a controlled environment for studying particle interactions.
- Electric fields can induce dipole moments in particles, influencing their arrangement.
Purpose of the Study:
- To investigate the phase transitions of 2D colloidal crystals in electric field traps.
- To determine the relationship between electric field strength, particle number, and crystal structure.
- To construct a phase diagram for these colloidal systems.
Main Methods:
- Confining 2D colloidal crystals within dielectrophoretic traps.
- Applying AC electric fields of varying strengths (0-750 V/cm).
- Analyzing resulting lattice structures and packing fractions (φ) for different particle numbers (N=21-25).
Main Results:
- At low fields, hexagonal close-packed lattice (p6m, φ=0.91) is observed.
- Higher fields induce dipole interactions, leading to structure changes dependent on N.
- N=24 forms square-packed lattice (p4m, φ=0.79); N=23 forms p2 lattice (φ=0.66).
- N=21, 22, 25 show mixed structures due to lateral forces and dipole interactions.
Conclusions:
- Electric field strength and particle number are key parameters controlling colloidal crystal phases.
- Tunable phase transitions and structures are achievable in 2D colloidal systems.
- A phase diagram mapping field strength vs. particle number provides insights into colloidal assembly.
Related Concept Videos
02:58Crystal Field Theory - Octahedral Complexes
31.8K
Crystal Field Theory
To explain the observed behavior of transition metal complexes (such as colors), a model involving electrostatic interactions between the electrons from the ligands and the electrons in the unhybridized d orbitals of the central metal atom has been developed. This electrostatic model is crystal field theory (CFT). It helps to understand, interpret, and predict the colors, magnetic behavior, and some structures of coordination compounds of transition metals.
CFT focuses on...
To explain the observed behavior of transition metal complexes (such as colors), a model involving electrostatic interactions between the electrons from the ligands and the electrons in the unhybridized d orbitals of the central metal atom has been developed. This electrostatic model is crystal field theory (CFT). It helps to understand, interpret, and predict the colors, magnetic behavior, and some structures of coordination compounds of transition metals.
CFT focuses on...
31.8K
02:39Phase Transitions: Melting and Freezing
15.7K
Heating a crystalline solid increases the average energy of its atoms, molecules, or ions, and the solid gets hotter. At some point, the added energy becomes large enough to partially overcome the forces holding the molecules or ions of the solid in their fixed positions, and the solid begins the process of transitioning to the liquid state or melting. At this point, the temperature of the solid stops rising, despite the continual input of heat, and it remains constant until all of the solid is...
15.7K
01:29The Colloidal State
152
The formation of a colloidal system is exemplified by an aqueous solution containing Cl− ions is introduced to another containing Ag+ ions, resulting in the precipitation of solid AgCl as extremely tiny crystals. Instead of settling out as a filterable precipitate, these crystals remain suspended in the liquid, showcasing a colloidal system.A colloidal system involves colloidal particles within the approximate range of 1 to 1000 nm in at least one dimension, dispersed in a medium called...
152
01:24Electrochemical Systems
124
Electrochemical systems provide a fascinating insight into the dynamic interplay of charged species within various phases. One notable example is the interaction between a membrane permeable to K⁺ ions but not to Cl⁻ ions, separating an aqueous KCl solution from pure water. As K⁺ ions diffuse through the membrane, they generate net charges on each phase, leading to a potential difference between them.Similarly, when a piece of Zn is immersed in an aqueous ZnSO₄ solution,...
124
02:31Phase Transitions
23.9K
Whether solid, liquid, or gas, a substance's state depends on the order and arrangement of its particles (atoms, molecules, or ions). Particles in the solid pack closely together, generally in a pattern. The particles vibrate about their fixed positions but do not move or squeeze past their neighbors. In liquids, although the particles are closely spaced, they are randomly arranged. The position of the particles are not fixed—that is, they are free to move past their neighbors to...
23.9K
01:21Phase Transitions
70
A phase transition is the process in which a substance changes from one state of matter to another, like from a solid to a liquid, liquid to gas, or vice versa, at a specific temperature and under given pressure conditions. This change is spontaneous and is affected by alterations in temperature and pressure. These parameters impact the strength of the forces between molecules (intermolecular forces) in the substance.During a phase transition, both the initial and final phases of the substance...
70