Colloids in external electric and magnetic fields: Colloidal crystals, pinning, chain formation, and electrokinetics

Zhao, Jinyu; Papadopoulos, Periklis; Roth, Marcel; Dobbrow, C.; Roeben, Eric; Schmidt, Annette; Butt, Hans‐Jürgen; Auernhammer, Günter K.; Vollmer, Doris

doi:10.1140/epjst/e2013-02064-1

Cited by 6 publications

(3 citation statements)

References 59 publications

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“…Accordingly, a collective ensemble of charged colloids responds in an even more complicated way to an external electric field. In this special issue, electrokinetics will be accessed by experimental studies [26,27] by computer simulations [28,29] and by statistical theory [30].…”

Section: Electric Fieldsmentioning

confidence: 99%

Introduction to colloidal dispersions in external fields

Löwen

2013

Eur. Phys. J. Spec. Top.

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Progress in the research area of colloidal dispersions in external fields within the last years is reviewed. Colloidal dispersions play a pivotal role as model systems for phase transitions in classical statistical mechanics. In recent years the leading role of colloids to realize model systems has become evident not only for equilibrium situations but also far away from equilibrium. By using external fields (such as shear flow, electric, magnetic or laseroptical fields as well as confinement), a colloidal suspension can be brought into nonequilibrium in a controlled way. Various kinds of equilibrium and nonequilibrium phenomena explored by colloidal dispersions are described providing also a guide and summary to this special issue. Particular emphasis is put on the comparison of real-space experiments, computer simulations and statistical theories.

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Section: Electric Fieldsmentioning

confidence: 99%

Introduction to colloidal dispersions in external fields

Löwen

2013

Eur. Phys. J. Spec. Top.

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“…Since phase transitions of colloids can be affected by external fields, we may induce various types of transitions by applying external fields in a reversible fashion, such as optical [16][17][18], magnetic [19][20][21], electric [20][21][22] or thermal fields (taking advantage of either thermophoresis [23][24][25] or temperature-dependant particle size [26,27]). Among these, the optical field is particularly interesting since it can be spatially localized in a region less than the size of colloids.…”

Section: Introductionmentioning

confidence: 99%

Externally driven local colloidal ordering induced by a pointlike heat source

Bruot

Tanaka

2019

Phys. Rev. Research

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We study here how phase transitions are induced in colloidal suspensions by a point-like heat source, an optically trapped metal oxide particle absorbing light. We find that thermophoresis increases the number density of colloids around the oxide particle, leading to the appearance of solid clusters. Our analysis based on thermophoresis reveals that the solid-fluid interface position is purely determined by the relationship of the particle concentration profile in the fluid state with the volume fraction of the phase transition, and no other effect of thermodynamics is seen in the cluster sizes. In this system, we observe the formation of face-centered cubic crystals, amorphous states, and structures with icosahedral order. This shows a rich possibility of non-trivial orderings under spatially controlled heterogeneous growth in external "semi-soft" potentials that are softer than walls but with substantial variations at the scale of a few particle diameters. Because of the tuneable rate of addition of particles to the clusters, we propose this method could be used to study the complex interplay of densification with local spatial confinement effects, kinetics, and ordering. *

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“…B4: Computer Simulation of Electrokinetics in Colloidal Systems [10] B7: Colloids in Crossed Electric and Magnetic Fields [11] B8: Phase Transitions of Confined Nanorods in Electric Fields [12] B9: Computer Simulations of Charged Colloids in Alternating Electric Fields [13]. It is our intention to document both the progress of this rapidly growing field and the achievements of the SFB TR 6 in this research area.…”

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confidence: 99%

Editorial

Löwen

Blaaderen²,

Dhont

et al. 2013

Eur. Phys. J. Spec. Top.

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EditorialColloidal dispersions are solutions of mesoscopic particles in a solvent. Among the various soft matter systems, colloidal dispersions play a prominent role as they can be both prepared and characterized in a controlled way. The effective interaction between the colloidal particles can be tailored by changing, e.g., the salt concentration in the solvent. Moreover, colloidal dispersions can be regarded as the simplest prototype of soft matter: the length scale separation between the molecular solvent and the mesoscopic particles is unique and complete. Spherical particles without any additional structure on the mesoscopic length scale possess the simplest and highest possible symmetry. This directly implies that a simple theoretical modelling of a single particle without many fitting parameters is possible. Exciting questions concern collective many-body effects induced by cooperation and self-organization of many particles. A striking advantage of colloidal dispersions lies in the fact that these questions can be studied simultaneously by using three different complementary methods, namely experiment, computer simulation, and theory.A profound theoretical understanding also provides an insight into the general basic principles and mechanisms of phase transformations such that colloids play an important role as model system for condensed matter in general. Colloids play a similarly dominant role in exploring changes of soft matter properties in external fields which can be used to control the colloidal samples.Bulk phase transitions of colloidal soft matter are meanwhile well-understood but important questions in confining geometries and additional external fields have been explored. Such fields can be realized by a shear flow or by the presence of electric and magnetic as well as laser-optical fields and topographical fields such as confining geometry. The motivation to study an external control via external fields has two main reasons: i) First, by definition, soft matter reacts sensitively upon external perturbations and manipulations. The occurrence of stable colloidal bulk samples is the exception rather than the rule, i.e., one has to protect the sample carefully against shear and other perturbations. ii) The second reason is that strong external fields induce qualitatively novel effects.Within the German-Dutch research network SFB TR6 "Colloidal Dispersions in External Fields" which was funded by the German science foundation and the Dutch FOM, there has been considerable scientific progress for colloids in external fields within the last 5 years. This will be reviewed in a bunch of 23 mini-review articles which cover various topics of colloids in shear, electric, magnetic, laser-optical fields and in confinement.First of all a general introduction to colloids in external fields is given in [1] which also provides a guide and a detailed classification of the different minireviews. Moreover the different subsequent minireviews correspond to different projects of the SFB TR6 according to different t...

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Colloids in external electric and magnetic fields: Colloidal crystals, pinning, chain formation, and electrokinetics

Cited by 6 publications

References 59 publications

Introduction to colloidal dispersions in external fields

Introduction to colloidal dispersions in external fields

Externally driven local colloidal ordering induced by a pointlike heat source

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