Melting and Liquid Structure in two Dimensions

Glaser, Matthew A.; Clark, Noel A.

doi:10.1002/9780470141410.ch7

Cited by 76 publications

(92 citation statements)

References 177 publications

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“…In fact, those experiments focused on testing 2D melting theories [3,4,41,42] rather than on searching for grain-boundary melting and interfacial melting.…”

Section: D Meltingmentioning

confidence: 99%

Melting of multilayer colloidal crystals confined between two walls

et al. 2011

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Video microscopy is employed to study the melting behaviors of multilayer colloidal crystals composed of diameter-tunable microgel spheres confined between two walls. We systematically explore film thickness effects on the melting process and on the phase behaviors of single crystal and polycrystalline films. Thick films (>4 layers) are observed to melt heterogeneously, while thin films (≤4 layers) melt homogeneously, even for polycrystalline films. Grain-boundary melting dominates other types of melting processes in polycrystalline films thicker than 12 layers. The heterogeneous melting from dislocations is found to coexist with grain-boundary melting in films between 5- and 12-layers. In dislocation melting, liquid nucleates at dislocations and forms lakelike domains embedded in the larger crystalline matrix; the "lakes" are observed to diffuse, interact, merge with each other, and eventually merge with large strips of liquid melted from grain boundaries. Thin film melting is qualitatively different: thin films homogeneously melt by generating many small defects which need not nucleate at grain boundaries or dislocations. For three- and four-layer thin films, different layers are observed to have the same melting point, but surface layers melt faster than bulk layers. Within our resolution, two- to four-layer films appear to melt in one step, while monolayers melt in two steps with an intermediate hexatic phase.

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“…In fact, those experiments focused on testing 2D melting theories [3,4,41,42] rather than on searching for grain-boundary melting and interfacial melting.…”

Section: D Meltingmentioning

confidence: 99%

Melting of multilayer colloidal crystals confined between two walls

et al. 2011

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“…While the liquid to crystal transition in three-dimensional systems is usually a first order transition, the situation in twodimensional systems is found to be more complex. Grain-boundary induced melting [6][7][8] or condensation of geometrical defects [9,10] suggest a first order phase transition, while the theory of John M. Kosterlitz, David J. Thouless, Bertrand Halperin, David R. Nelson, and Allan P. Young [11][12][13][14][15][16][17], the so called KTHNY theory, predicted a melting process via two continuous phase transitions with an intermediate phase.…”

Section: Introductionmentioning

confidence: 99%

Two-dimensional colloidal systems in time-dependent magnetic fields

Dillmann

Maret

Keim

2013

Eur. Phys. J. Spec. Top.

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Abstract. We use super-paramagnetic colloidal particles confined by gravitation to a flat water-air interface as a model system to study the non-equilibrium liquid-solid phase transition in two dimensions. The system temperature is adjustable by changing the strength of an external magnetic field perpendicular to the water-air interface. Increasing the magnetic field on a timescale of milliseconds quenches the liquid to a strongly super-cooled state. If the system is cooled down out of equilibrium the solidification differs drastically from the equilibrium melting and freezing scenario as no hexatic phase is observable. The system solidifies to a polycrystalline structure with many grains of different orientations. Since the local closed packed order in two dimensions is sixfold, in both the fluid and the crystalline state, sensitive measures have to be developed. In the present manuscript we compare different methods to identify crystalline cluster locally and motivate the threshold values. Those are chosen in comparison with the isotropic fluid on one hand and large mono-crystals in thermal equilibrium on the other hand. With the given criteria for crystalline cluster the cluster are found not to be circular and fractal dimensions of the grains are given.

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“…12 Besides empirical criteria, fundamental theories of freezing/melting in 2D have been formulated. KosterlitzThouless-Halperin-Nelson-Young ͑KTHNY͒ theory [13][14][15][16] and other 2D melting theories, [17][18][19] however, address singlecrystal melting. In principle, these melting theories can be applied to freezing, but in practice homogenous nucleation at finite quench rates most often produces polycrystalline solids upon freezing.…”

Section: Introductionmentioning

confidence: 99%

Two-dimensional freezing criteria for crystallizing colloidal monolayers

Wang

Alsayed

Yodh

et al. 2010

The Journal of Chemical Physics

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Recommended CitationWang, Z., Alsayed, A. M., Yodh, A. G., & Han, Y. (2010). Two-dimensional freezing criteria for crystallizing colloidal monolayers. Retrieved from http://repository.upenn.edu/physics_papers/32 Two-dimensional freezing criteria for crystallizing colloidal monolayers AbstractVideo microscopy was employed to explore crystallization of colloidal monolayers composed of diametertunable microgel spheres. Two-dimensional (2D) colloidal liquids were frozen homogenously into polycrystalline solids, and four 2D criteria for freezing were experimentally tested in thermal systems for the first time: the Hansen-Verlet freezing rule, the Löwen-Palberg-Simon dynamical freezing criterion, and two other rules based, respectively, on the split shoulder of the radial distribution function and on the distribution of the shape factor of Voronoi polygons. Importantly, these freezing criteria, usually applied in the context of single crystals, were demonstrated to apply to the formation of polycrystalline solids. At the freezing point, we also observed a peak in the fluctuations of the orientational order parameter and a percolation transition associated with caged particles. Speculation about these percolated clusters of caged particles casts light on solidification mechanisms and dynamic heterogeneity in freezing. Video microscopy was employed to explore crystallization of colloidal monolayers composed of diameter-tunable microgel spheres. Two-dimensional ͑2D͒ colloidal liquids were frozen homogenously into polycrystalline solids, and four 2D criteria for freezing were experimentally tested in thermal systems for the first time: the Hansen-Verlet freezing rule, the Löwen-PalbergSimon dynamical freezing criterion, and two other rules based, respectively, on the split shoulder of the radial distribution function and on the distribution of the shape factor of Voronoi polygons. Importantly, these freezing criteria, usually applied in the context of single crystals, were demonstrated to apply to the formation of polycrystalline solids. At the freezing point, we also observed a peak in the fluctuations of the orientational order parameter and a percolation transition associated with caged particles. Speculation about these percolated clusters of caged particles casts light on solidification mechanisms and dynamic heterogeneity in freezing.

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Melting and Liquid Structure in two Dimensions

Cited by 76 publications

References 177 publications

Melting of multilayer colloidal crystals confined between two walls

Melting of multilayer colloidal crystals confined between two walls

Two-dimensional colloidal systems in time-dependent magnetic fields

Two-dimensional freezing criteria for crystallizing colloidal monolayers

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