Quasi-2D Monte Carlo simulations of a colloidal dispersion composed of magnetic plate-like particles with magnetic moment normal to the particle axis

Satoh, Akira; Sakuda, Yasuhiro

doi:10.1080/00268970902994301

Cited by 16 publications

(11 citation statements)

References 19 publications

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“…In the field of fluid engineering, the main targets for the application of a suspension with magneto-rheological properties has been actuators and dampers, therefore the influence of particle aggregation on the rheological properties of a magnetic suspension has being investigated [2,3]. In the field of colloid interface science, high-density recording materials [4,5] and optical units [6][7][8][9][10] are the main applications, therefore our research group has been investigating the self-organization of magnetic particles [11], the control of particle orientation on material surfaces [12] and phase change phenomena [13].…”

Section: Introductionmentioning

confidence: 99%

On the orientational characteristics and transport coefficients of an oblate spheroidal hematite particle in a simple shear flow

Satoh

2012

Molecular Physics

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We have developed the basic equation of the orientational distribution function of oblate spheroidal hematite particles with rotational Brownian motion in a simple shear flow under an applied magnetic field. An oblate spheroidal hematite particle has an important characteristic in that it is magnetized in a direction normal to the particle axis. Since a dilute dispersion is addressed in the present study, we have taken into account only the friction force (torque) whilst neglecting the hydrodynamic interactions among the particles. This basic equation has been solved numerically in order that we may investigate the dependence of the orientational distribution on the magnetic field strength, shear rate and rotational Brownian motion and the relationship between the orientational distribution and the transport coefficients such as viscosity and diffusion coefficient. We found that if the effect of the magnetic field is more dominant, the particle inclines in such a way that the oblate surface aligns in the magnetic field direction. If the Peclet number increases and the effect of the shear flow becomes more dominant, the particle inclines such that the oblate surface tilts in the shear flow direction. The viscosity due to the magnetic torque is shown to increase as the magnetic field increases, since the magnetic torque due to the applied magnetic field becomes the more dominant effect. Moreover, the viscosity increase is shown to be more significant for a larger aspect ratio or for a more oblate hematite particle. We have applied the analysis to the problem of particle sedimentation under gravity in the presence of a magnetic field applied in the sedimentation direction. The particles are found to sediment with the oblate surface aligning more significantly in the sedimentation direction as the applied magnetic field strength increases.

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Section: Introductionmentioning

confidence: 99%

On the orientational characteristics and transport coefficients of an oblate spheroidal hematite particle in a simple shear flow

Satoh

2012

Molecular Physics

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“…Quasi-two-dimensional Monte Carlo simulations of a colloidal dispersion composed of magnetic platelike particles are reported in Ref. 25 Both integral equation theory [26][27][28] and DFT 9,29,30 are powerful tools for the theoretical study of platelet systems. A fundamental measures DFT for circular hard platelets with vanishing thickness 31 was shown to give results for the coexistence densities and order parameter at coexistence of the IN transition in bulk that are superior to results from Onsager theory when compared to simulation data ͑see Ref.…”

Section: Introductionmentioning

confidence: 99%

Sedimentation equilibrium of colloidal platelets in an aligning magnetic field

Reich

Schmidt

2010

The Journal of Chemical Physics

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We consider colloidal platelets under the influence of gravity and an external aligning (magnetic) field. The system is studied using a fundamental measures density functional theory for model platelets of circular shape and vanishing thickness. In the gravity-free case, the bulk phase diagram exhibits paranematic-nematic phase coexistence that vanishes at an upper critical point upon increasing the strength of the aligning field. Equilibrium sedimentation profiles display a paranematic-nematic interface, which moves to smaller (larger) height upon increasing the strength of gravity (the aligning field). The density near the bottom of the system decreases upon increasing the strength of the aligning field at fixed strength of gravity. Using a simple model for the birefringence properties of equilibrium states, we simulate the color variation with height, as can be observed in samples between crossed polarizers.

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“…The influence of the magnetic field on a particle can be evaluated by a comparison with the thermal energy and is given by eq 6. 27 A particle is magnetically oriented at a high enough product of mH when ξ M > 1. This means that a lower magnetic field is required to orient larger particles with large magnetic moments than for the smaller or even superparamagnetic particles with small magnetic moments.…”

Section: ■ Theoretical Basismentioning

confidence: 99%

The Alignment of Barium Ferrite Nanoparticles from Their Suspensions in Electric and Magnetic Fields

Lisjak

Ovtar

2012

J. Phys. Chem. B

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The alignment of plate-like barium ferrite nanoparticles, with diameters of 10-350 nm and thicknesses of 3-10 nm, in electric and/or magnetic fields was studied. Stable suspensions were prepared in 1-butanol with dodecylbenzenesulphonic acid as a surfactant. The deposits were produced from the suspensions with classic electrophoretic deposition, electrophoretic deposition in a magnetic field, and with drying in a magnetic field. The experiments, supported by theoretical calculations, show that the alignment of the nanoplates in the deposits was determined by the interplay between the hydrodynamic, electric, and magnetic forces. The preferential alignment of the nanoplates in plane with the substrate coincided with their magnetic orientation, and it increased with the shape anisotropy of the particles. The deposits were sintered at 1150 °C for 5 h to obtain ceramic films, which showed a magnetic orientation up to 90%.

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Quasi-2D Monte Carlo simulations of a colloidal dispersion composed of magnetic plate-like particles with magnetic moment normal to the particle axis

Cited by 16 publications

References 19 publications

On the orientational characteristics and transport coefficients of an oblate spheroidal hematite particle in a simple shear flow

On the orientational characteristics and transport coefficients of an oblate spheroidal hematite particle in a simple shear flow

Sedimentation equilibrium of colloidal platelets in an aligning magnetic field

The Alignment of Barium Ferrite Nanoparticles from Their Suspensions in Electric and Magnetic Fields

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