Equilibrium magnetization of concentrated ferrocolloids

Pshenichnikov, A. F.

doi:10.1016/0304-8853(94)01632-1

Cited by 80 publications

(45 citation statements)

References 13 publications

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“…However, experiments on concentrated ferrofluids have revealed an essential deviation from the Langevin formula [3]. The initial susceptibility increases with the particle concentration much faster than that predicted in Eq.…”

Section: Introductionmentioning

confidence: 95%

Molecular dynamics study on the equilibrium magnetization properties and structure of ferrofluids

2002

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We investigate in detail the initial susceptibility, magnetization curves, and microstructure of ferrofluids in various concentration and particle dipole moment ranges by means of molecular dynamics simulations. We use the Ewald summation for the long-range dipolar interactions, take explicitly into account the translational and rotational degrees of freedom, coupled to a Langevin thermostat. When the dipolar interaction energy is comparable with the thermal energy, the simulation results on the magnetization properties agree with the theoretical predictions very well.For stronger dipolar couplings, however, we find systematic deviations from the theoretical curves.We analyze in detail the observed microstructure of the fluids under different conditions. The formation of clusters is found to enhance the magnetization at weak fields and thus leads to a larger initial susceptibility. The influence of the particle aggregation is isolated by studying ferrosolids, which consist of magnetic dipoles frozen in at random locations but which are free to rotate.Due to the artificial suppression of clusters in ferro-solids the observed susceptibility is considerably lowered when compared to ferrofluids.

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Section: Introductionmentioning

confidence: 95%

Molecular dynamics study on the equilibrium magnetization properties and structure of ferrofluids

2002

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“…Pshenichnikov [93] compares several theories, namely the Onsager model, the Weiss model, the MSA and a theory by Ivanov et al [94] with experimental data in a similar range of φ and λ. The latter theory [94] deals with the equilibrium magnetization for arbitrary fields.…”

Section: G Applications To Ferrofluidsmentioning

confidence: 99%

Magnetic properties of colloidal suspensions of interacting magnetic particles

2004

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We review equilibrium thermodynamic properties of systems of magnetic particles like ferrofluids in which dipolar interactions play an important role. The review is focussed on two subjects: (i) the magnetization with the initial magnetic susceptibility as a special case and (ii) the phase transition behavior. Here the condensation ("gas/liquid") transition in the subsystem of the suspended particles is treated as well as the isotropic/ferromagnetic transition to a state with spontaneously generated long-range magnetic order.

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“…From the VSM data, using the mean-spherical and the high-temperature approximation models [7], the value of the magnetization in the saturation state was calculated as M S ∼ = (29.19 ± 0.03) kA · m −1 . The saturation magnetization allowed us to determine the volume fraction of the magnetite phase from the expression,…”

Section: Methodsmentioning

confidence: 99%

Heating Characteristics of Transformer Oil-Based Magnetic Fluids of Different Magnetic Particle Concentrations

2010

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The heating ability of mineral oil-based magnetic fluids with different magnetic particle concentrations is studied. The calorimetric measurements were carried out in an alternating magnetic field of 500 A · m −1 to 2500 A · m −1 amplitude and of 1500 kHz frequency. The revealed H n law-type dependence of the temperature increase rate, (dT /dt) t=0 , on the amplitude of the magnetic field indicates the presence of superparamagnetic and partially ferromagnetic particles in the tested samples since n > 2. The specific absorption rate (SAR) defined as the rate of energy absorption per unit mass increases with a decrease of the volume fraction of the dispersed phase. This can be explained by the formation of aggregates in the samples with a higher concentration of magnetic particles.

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Equilibrium magnetization of concentrated ferrocolloids

Cited by 80 publications

References 13 publications

Molecular dynamics study on the equilibrium magnetization properties and structure of ferrofluids

Molecular dynamics study on the equilibrium magnetization properties and structure of ferrofluids

Magnetic properties of colloidal suspensions of interacting magnetic particles

Heating Characteristics of Transformer Oil-Based Magnetic Fluids of Different Magnetic Particle Concentrations

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