Tuning the Colloidal Crystal Structure of Magnetic Particles by External Field

Abstract

Manipulation of the self-assembly of magnetic colloidal particles by an externally applied magnetic field paves a way toward developing novel stimuli responsive photonic structures. Using microradian X-ray scattering technique we have investigated the different crystal structures exhibited by self-assembly of core-shell magnetite/silica nanoparticles. An external magnetic field was employed to tune the colloidal crystallization. We find that the equilibrium structure in absence of the field is random hexagonal close-packed (RHCP) one. External field drives the self-assembly toward a body-centered tetragonal (BCT) structure. Our findings are in good agreement with simulation results on the assembly of these particles.

Ptychographic X‐Ray Imaging of Colloidal Crystals

“…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 .…”

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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.

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Bio-Inspired Self-Adhesive Bright Non-iridescent Graphene Pigments

“…With the typical advantages of fastness, non-toxicity, and environmental protection, structural-color materials have been broadly applied in the fields of decoration, anticounterfeiting, functional materials, and biological or chemical detection. [1][2][3][4][5][6][7][8][9][10][11][12][13] In particular, the discovery and development of non-iridescent structural-color materials has expanded their potential values, based on the special features of angle independence and wide-angle display, which are attributed to the characteristic longrange disorder assembly of those component colloidal nanoparticles. [14][15][16][17] However, due to the lack of absorbing materials to decrease the incoherent scattering that leads to insufficient color saturation, common non-iridescent colors are often shown to be pale and insufficiently bright.…”

Reconfigurable assembly of superparamagnetic colloids confined in thermo-reversible microtubes

“…[1][2][3][4][5][6][7][8] Recently non-linear magnetic assembly was reported for new types of magnetic colloids with uneven distributions of dipoles. [1][2][3][4][5][6][7][8] Recently non-linear magnetic assembly was reported for new types of magnetic colloids with uneven distributions of dipoles.…”