arXiv subjects

Y. C. Jian

Publications and source records attributed to Y. C. Jian.

5 recordsLinked to original sources

arXiv2008

Structure of polydisperse inverse ferrofluids: Theory and computer simulation

By using theoretical analysis and molecular dynamics simulations, we investigate the structure of colloidal crystals formed by nonmagnetic microparticles (or magnetic holes) suspended in ferrofluids (called inverse ferrofluids), by taking into account the effect of polydispersity in size of the nonmagnetic microparticles. Such polydispersity often exists in real situations. We obtain an analytical expression for the interaction energy of monodisperse, bidisperse, and polydisperse inverse ferrofluids. Body-centered tetragonal (bct) lattices are shown to possess the lowest energy when compared with other sorts of lattices and thus serve as the ground state of the systems. Also, the effect of microparticle size distributions (namely, polydispersity in size) plays an important role in the formation of various kinds of structural configurations. Thus, it seems possible to fabricate colloidal crystals by choosing appropriate polydispersity in size.

cond-mat.soft↗

arXiv2008

Magnetophoresis of nonmagnetic particles in ferrofluids

Ferrofluids containing nonmagnetic particles are called inverse ferrofluids. On the basis of the Ewald-Kornfeld formulation and the Maxwell-Garnett theory, we theoretically investigate the magnetophoretic force exerting on the nonmagnetic particles in inverse ferrofluids due to the presence of a nonuniform magnetic field, by taking into account the structural transition and long-range interaction. We numerically demonstrate that the force can be adjusted by choosing appropriate lattices, volume fractions, geometric shapes, and conductivities of the nonmagnetic particles, as well as frequencies of external magnetic fields.

physics.chem-ph↗

arXiv2008

Theory of second-harmonic generation in colloidal crystals

On the basis of the Edward-Kornfeld formulation, we study the effective susceptibility of secondharmonic generation (SHG) in colloidal crystals, which are made of graded metallodielectric nanoparticles with an intrinsic SHG susceptibility suspended in a host liquid. We find a large enhancement and redshift of SHG responses, which arises from the periodic structure, local field effects and gradation in the metallic cores. The optimization of the Ewald-Kornfeld formulation is also investigated.

physics.optics↗

arXiv2006

Nonlinear response of the magnetophoresis in inverse ferrofluids

Taking into account the structural transition and long-range interaction (lattice effect), we resort to the Ewald-Kornfeld formulation and developed Maxwell-Garnett theory for uniaxially anisotropic suspensions to calculate the effective permeability of inverse ferrofluids. And we also consider the effect of volume fraction to the magnetophoretic force on the nonmagnetic spherical particles submerged in ferrofluids in the presence of nonuniform magnetic field. We find that the coupling of ac and dc field case can lead to fundamental and third harmonic response in the effective magnetophoresis and changing the aspect ratio in both prolate and oblate particles can alter the harmonic and nonharmonic response and cause the magnetophoretic force vanish.

cond-mat.soft↗

arXiv2006

Magnetophoresis of ferrofluid in microchannel system and its nonlinear effect

We have studied the magnetophoretic particle separation and its nonlinear behavior of ferrofluids in microchannel which is proposed by Furlani. The magnetic gradient force is caused by an bias field and the polarized magnets and is found to be spatially uniform in the channel section which can be used for particle selecting or separation. We have derived the equations of nonlinear magnetization of magnetic particles which cause the harmonics of magnetophoresis. The Langevin model and generalized Clausius-Mossotti equation used show how the normal and longitude anomalous anisotropic effect the permeability of ferrofluids, thus the magnetic force. Our analysis demonstrates the viability of using the microchannel system for various bioapplications and other characterization of fluid transporting and the time-varying magnetic field can be potentially used for an integrated magnetometer and influences the the viscosity and effective permeability in ferrofluids.

physics.bio-ph↗