Surface-assisted single-crystal formation of charged colloids

Arai, Shunto; Tanaka, Hajime

doi:10.1038/nphys4034

Cited by 62 publications

(72 citation statements)

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“…where r e is the classical electron radius. Substituting Equation (13) in Equation (12), we obtain for the phase of the object function (12) are determined directly from the experimental data, for example, by fast converging alternating projections algorithm. [52] Experimental Setup: The X-ray ptychography experiment on a colloidal crystal has been performed at the coherence beamline P10 of the PETRA III synchrotron at DESY, Hamburg with an incident X-ray photon energy of 8 keV.…”

Section: Theory and Experimental Sectionmentioning

confidence: 99%

“…Colloidal crystals are being actively employed as an important model system to study melting, freezing, and solid‐solid phase transitions as a function of osmotic pressure and anisotropy of interparticle interaction due to particle shape, patchiness, or dipolar interactions . The flexibility of colloidal crystals and their response to external stimuli along with their unique optical properties such as the strongly pronounced structural color and photonic band gap makes them attractive for many applications .…”

Section: Introductionmentioning

confidence: 99%

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Ptychographic X‐Ray Imaging of Colloidal Crystals

Lazarev

Besedin

Zozulya

et al. 2017

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dipolar interactions. [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15] The flexibility of colloidal crystals and their response to external stimuli [16][17][18] along with their unique optical properties such as the strongly pronounced structural color and photonic band gap makes them attractive for many applications. [19][20][21][22][23][24][25] Moreover, defects, which determine the mechanical properties of many engineering materials such as metals, [26] can be studied with "atomic" resolution using colloidal crystals. [27][28][29] The high penetration depth of X-rays makes them an ideal tool to access important statistically averaged spatial information about the colloidal crystal structure and disorder over macroscopic sample volume. [7,30,31] Further access to local structure of colloidal crystals can be gained by using microscopy with Fresnel optics and soft X-rays, [32,33] but unfortunately the use of soft X-rays significantly limits the penetration depth. Alternatively, compound refractive lenses (CRLs) can be used as an objective lens for hard X-rays to study thicker samples. [34][35][36] This technique provides full field of view, however, resolution is limited by the resolving power of the optical elements and contrast is limited by using hard X-rays. [37] Ptychographic coherent X-ray imaging is applied to obtain a projection of the electron density of colloidal crystals, which are promising nanoscale materials for optoelectronic applications and important model systems. Using the incident X-ray wavefield reconstructed by mixed states approach, a high resolution and high contrast image of the colloidal crystal structure is obtained by ptychography. The reconstructed colloidal crystal reveals domain structure with an average domain size of about 2 µm. Comparison of the domains formed by the basic close-packed structures, allows us to conclude on the absence of pure hexagonal close-packed domains and confirms the presence of random hexagonal close-packed layers with predominantly face-centered cubic structure within the analyzed part of the colloidal crystal film. The ptychography reconstruction shows that the final structure is complicated and may contain partial dislocations leading to a variation of the stacking sequence in the lateral direction. As such in this work, X-ray ptychography is extended to high resolution imaging of crystalline samples. Ptychography [+]

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Section: Theory and Experimental Sectionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Ptychographic X‐Ray Imaging of Colloidal Crystals

Lazarev

Besedin

Zozulya

et al. 2017

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“…Ga also shows a promising potential in monatomic PC memory devices for data storage, superconductivity, metamaterial, and reversible adhesion . To reverse the supercooling of liquid Ga, external perturbations are applied to induce nucleation and subsequent crystal growth . Even though molecular liquids are promising candidates to study phase transformation at ambient pressures and moderate temperatures, it is rather difficult to practically monitor the exact site of nucleation, since nucleation is a stochastic process …”

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confidence: 99%

“…The wrinkling instability emerged at the interface to relieve the applied compressive stress. The crystallization of the liquid droplet was realized through a contact with a seeding crystal of solid Ga . We visualized the spatiotemporal evolution of the crystallization dynamics on transparent glass, indium tin oxide coated glass (ITO‐glass), and zinc selenide (ZnSe) substrates ( Figure ; Movies S1, S2, and S3, Supporting Information).…”

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Thermal Effects on the Crystallization Kinetics, and Interfacial Adhesion of Single‐Crystal Phase‐Change Gallium

2020

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Although substrates play an important role upon crystallization of supercooled liquids, the influences of surface temperature and thermal property have remained elusive. Here, the crystallization of supercooled phase‐change gallium (Ga) on substrates with different thermal conductivity is studied. The effect of interfacial temperature on the crystallization kinetics, which dictates thermo‐mechanical stresses between the substrate and the crystallized Ga, is investigated. At an elevated surface temperature, close to the melting point of Ga, an extended single‐crystal growth of Ga on dielectric substrates due to layering effect and annealing is realized without the application of external fields. Adhesive strength at the interfaces depends on the thermal conductivity and initial surface temperature of the substrates. This insight can be applicable to other liquid metals for industrial applications, and sheds more light on phase‐change memory crystallization.

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Photonic Microcapsules Containing Single‐Crystal Colloidal Arrays with Optical Anisotropy

et al. 2019

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bcc) structures, [6,7] none of which are compatible with curved surfaces. Therefore, it is difficult to predict the optimum colloidal arrangement in a spherical geometry.The optimum arrangement of colloids confined to a 2D spherical surface has been thoroughly investigated using Pickering emulsions, or particle-stabilized emulsions, as a model system. [8] The colloids form dislocations composed of a series of fivefold and sevenfold defects to accommodate the nonzero curvature, and the number of dislocations increases as the curvature decreases. The formation of 3D spherical crystals has been mostly studied using slowly shrinking drops, which predominantly results in isotropic supraballs composed of repeated layers from the spherical surface toward the center, where each layer is composed of a hexagonal array of colloidal particles; [1,[9][10][11][12][13] here, we refer to the structure as an onion-like structure. However, as each layer has many dislocations identical to those for colloids confined to a 2D spherical surface, the supraball contains a high density of defects, which is expected to be energetically unfavorable. There has been few reports about the formation of single-crystal or multigrain structure occupying the entire spherical volume; [14][15][16][17] according to these reports, quantum-dot nanoparticles form fcc crystals during the shrinkage of droplets, which showed no photonic effect due to the small lattice dimension. Recently, it was reported that colloidal particles form icosahedron and its derivatives in very slowly shrinking droplets. These nanoparticles and colloids are assembled by entropy.In the current work, we studied the crystallization behavior of charged colloidal particles with repulsive interparticle potential confined in water-in-oil-in-water double-emulsion drops or microcapsules. The particles were initially in the fluid phase in the inner water drop, but eventually spontaneously formed colloidal crystals to reduce the repulsive energy. The crystallization started along the spherical interface of the inner drop as a result of heterogeneous nucleation. [18] In general, crystal growth behavior varies depending on the strength of repulsion at the average interparticle separation. [6,19] In the current work, strong repulsion between particles was shown to lead to fast growth of the crystals from the surface of the microcapsule, forming an isotropic onion-like structure. By contrast, weak repulsion led to slow growth and fusion of crystallites, eventually resulting in Colloidal particles with a repulsive interparticle potential spontaneously form crystalline lattices, which are used as a motif for photonic materials. It is difficult to predict the crystal arrangement in spherical volume as lattices are incompatible with a spherical surface. Here, the optimum arrangement of charged colloids is experimentally investigated by encapsulating them in double-emulsion drops. Under conditions of strong interparticle repulsion, the colloidal crystal rapidly grows from the surface toward the ce...

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Surface-assisted single-crystal formation of charged colloids

Cited by 62 publications

References 47 publications

Ptychographic X‐Ray Imaging of Colloidal Crystals

Ptychographic X‐Ray Imaging of Colloidal Crystals

Thermal Effects on the Crystallization Kinetics, and Interfacial Adhesion of Single‐Crystal Phase‐Change Gallium

Photonic Microcapsules Containing Single‐Crystal Colloidal Arrays with Optical Anisotropy

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