Programmed symmetry lowering in 2D colloids

Tang, Yeke; Malzbender, Rainer M.; Mockler, R. C.; O'Sullivan, W.J.; Beall, James A.

doi:10.1088/0305-4470/20/3/013

Cited by 14 publications

(13 citation statements)

References 6 publications

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“…Their crystallization kinetics and mechanisms have been investigated in great detail in experiment and theory [6,7]. Since the pioneering work of Tang et al [8], there has been a growing interest in obtaining large single crystals (2D or 3D) with predetermined location, structure and orientation. This is motivated by their use as model systems for fundamental issues in condensed matter physics [9] and their potential use as photonic or phononic materials [10,11].…”

Section: Introductionmentioning

confidence: 99%

Controlled assembly of single colloidal crystals using electro-osmotic micro-pumps

Niu

Oğuz

Müller

et al. 2017

Phys. Chem. Chem. Phys.

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Abstract:We assemble charged colloidal spheres at deliberately chosen locations on a charged unstructured glass substrate utilizing ion exchange based electro-osmotic micro-pumps.Using microscopy, a simple scaling theory and Brownian Dynamics simulations, we systematically explore the control parameters of crystal assembly and the mechanisms through which they depend on the experimental boundary conditions. We demonstrate that crystal quality depends crucially on the assembly distance of the colloids. This is understood as resulting from the competition between inward transport by the electro-osmotic pump flow and the electro-phoretic outward motion of the colloids. Optimized conditions include substrates of low and colloids of large electro-kinetic mobility. Then a sorting of colloids by size is observed in binary mixtures with larger particles assembling closer to the ion exchanger beads. Moreover, mono-sized colloids form defect free single domain crystals which grow outside a colloid-free void with facetted inner crystal boundaries centred on the ion exchange particle. This works remarkably well, even with irregularly formed ion exchange resin splinters.

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Section: Introductionmentioning

confidence: 99%

Controlled assembly of single colloidal crystals using electro-osmotic micro-pumps

Niu

Oğuz

Müller

et al. 2017

Phys. Chem. Chem. Phys.

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“…Rather, the crystallization scenario is flexibly altered by external influences. External fields, 4,5 such as electric fields, [6][7][8] optical fields, 9 shear forces, 10 structured templates, 11 or specific confining geometries, 12 have been successfully applied to achieve particular micro-structures not available from undisturbed bulk samples.…”

Section: Introductionmentioning

confidence: 99%

Colloidal crystallization in the quasi-two-dimensional induced by electrolyte gradients

Reinmüller

Oğuz

Messina

et al. 2012

The Journal of Chemical Physics

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We investigated driven crystal formation events in thin layers of sedimented colloidal particles under low salt conditions. Using optical microscopy, we observe particles in a thermodynamically stable colloidal fluid to move radially converging towards cation exchange resin fragments acting as seed particles. When the local particle concentration has become sufficiently large, subsequently crystallization occurs. Brownian dynamics simulations of a 2D system of purely repulsive point-like particles exposed to an attractive potential, yield strikingly similar scenarios, and kinetics of accumulation and micro-structure formation. This offers the possibility of flexibly designing and manufacturing thin colloidal crystals at controlled positions and thus to obtain specific micro-structures not accessible by conventional approaches. We further demonstrate that particle motion is correlated with the existence of a gradient in electrolyte concentration due to the release of electrolyte by the seeds.

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“…The colloidal model system has already been frequently, and successfully, used for investigating both homogeneous [3][4][5][6] crystallization and crystallization close to a wall [7][8][9]. Recently, these studies have received a great impulse when it was shown that it is possible to perform a full three-dimensional (3D) real-space analysis by using confocal microscopy and fluorescently labeled colloids [10,11].…”

Section: Introductionmentioning

confidence: 99%

“…The possibilities of this technique were further demonstrated by several papers addressing hard-sphere glass formation [11][12][13], crystal nucleation [6], and epitaxial hard-sphere crystallization [14][15][16]. Several different techniques, e.g., electron-beam lithography, soft lithography [17], and optical tweezers [18], provide the possibility to pattern substrates on length scales comparable to those of colloids [9]. The manipulation of colloidal crystallization by using patterned templates, i.e., colloidal epitaxy [14,15], extends the use of the colloidal model system to include epitaxial crystallization as well.…”

Section: Introductionmentioning

confidence: 99%

Epitaxial growth of a colloidal hard-sphere hcp crystal and the effects of epitaxial mismatch on crystal structure

et al. 2004

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We demonstrate the epitaxial growth of hard-sphere hcp and double hcp crystals using a surface pattern that directly dictates the stacking sequence. A detailed three-dimensional analysis based on real-space measurements is performed on crystal structure as a function of template-crystal mismatch, which demonstrates the possibilities of colloidal epitaxy as a model system for studying the effects of a patterned substrate on crystal structure. Perfect template-induced hcp-crystal growth occurs at an isotropically deformed template. At deformed lattices we observe growth of a non-close-packed superstructure and of a perfect (100)-aligned fcc crystal. Small mismatches lead to increased out-of-plane displacements followed by a structural breakup in "crystal" grains where particle positions in successive layers are strictly periodic and "defect" grains where these positions are displaced with respect to each other. Large mismatches prevent crystallization in the surface layers. The volume fraction was found to vary drastically (up to about 20%) as a function of template deformation.

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Programmed symmetry lowering in 2D colloids

Cited by 14 publications

References 6 publications

Controlled assembly of single colloidal crystals using electro-osmotic micro-pumps

Controlled assembly of single colloidal crystals using electro-osmotic micro-pumps

Colloidal crystallization in the quasi-two-dimensional induced by electrolyte gradients

Epitaxial growth of a colloidal hard-sphere hcp crystal and the effects of epitaxial mismatch on crystal structure

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