Equilibrium properties of ferrocolloids

Buyevich, Yu.A.; Иванов, А. П.

doi:10.1016/0378-4371(92)90037-q

Cited by 195 publications

(129 citation statements)

References 19 publications

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“…It has been checked carefully that the low-wavevector anomalies in S(k) are not artifacts arising from truncation errors or similar problems in the numerical Fourier transforms, which are best carried out in cylindrical polar coordinates. 41 Acknowledging this fundamental shortcoming of the theory, the unphysical regions in Fig. 7 are highlighted with dashed lines, and in what follows S(k) will be truncated at the wavevector where an unphysical extremum or point of inflexion occurs.…”

Section: B Structure Factor S(k)mentioning

confidence: 99%

Theory and simulation of anisotropic pair correlations in ferrofluids in magnetic fields

Elfimova

Иванов

Camp

2012

The Journal of Chemical Physics

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Articles you may be interested inMagnetic field role on the structure and optical response of photonic crystals based on ferrofluids containing Co0.25Zn0.75Fe2O4 nanoparticles J. Appl. Phys. 115, 193502 (2014) Anisotropic pair correlations in ferrofluids exposed to magnetic fields are studied using a combination of statistical-mechanical theory and computer simulations. A simple dipolar hard-sphere model of the magnetic colloidal particles is studied in detail. A virial-expansion theory is constructed for the pair distribution function (PDF) which depends not only on the length of the pair separation vector, but also on its orientation with respect to the field. A detailed comparison is made between the theoretical predictions and accurate simulation data, and it is found that the theory works well for realistic values of the dipolar coupling constant (λ = 1), volume fraction (ϕ ≤ 0.1), and magnetic field strength. The structure factor is computed for wavevectors either parallel or perpendicular to the field. The comparison between theory and simulation is generally very good with realistic ferrofluid parameters. For both the PDF and the structure factor, there are some deviations between theory and simulation at uncommonly high dipolar coupling constants, and with very strong magnetic fields. In particular, the theory is less successful at predicting the behavior of the structure factors at very low wavevectors, and perpendicular Gaussian density fluctuations arising from strongly correlated pairs of magnetic particles. Overall, though, the theory provides reliable predictions for the nature and degree of pair correlations in ferrofluids in magnetic fields, and hence should be of use in the design of functional magnetic materials.

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Section: B Structure Factor S(k)mentioning

confidence: 99%

Theory and simulation of anisotropic pair correlations in ferrofluids in magnetic fields

Elfimova

Иванов

Camp

2012

The Journal of Chemical Physics

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“…The latter theory [94] Kalikmanov [92] proposes in 1999 the so-called algebraic perturbation theory that is corrected by Szalai, Chan and Henderson [95] and found to be identical to the cluster expansion theory of Tani et al [26].…”

Section: G Applications To Ferrofluidsmentioning

confidence: 96%

“…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] Kalikmanov [92] proposes in 1999 the so-called algebraic perturbation theory that is corrected by Szalai, Chan and Henderson [95] and found to be identical to the cluster expansion theory of Tani et al [26].…”

Section: G Applications To Ferrofluidsmentioning

confidence: 99%

Magnetic Properties of Colloidal Suspensions of Interacting Magnetic Particles

Huke

Luecke

2005

ChemInform

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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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“…13 Upon applying magnetic field to a sample, dipolar moments tend to align themselves towards the field direction. As a result, short chains that are either already formed in the sample or are being formed due to the intensification of the dipolar moments in response to the magnetic field will be oriented toward the field.…”

Section: Effects Of Magnetic Field On a Sample With Known Concentrationmentioning

confidence: 99%

Direct observations of field-induced assemblies in magnetite ferrofluids

Mousavi

Khapli

Kumar

2015

Journal of Applied Physics

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Evolution of microstructures in magnetite-based ferrofluids with weak dipolar moments (particle size 10 nm) is studied with an emphasis on examining the effects of particle concentration (/) and magnetic field strength (H) on the structures. Nanoparticles are dispersed in water at three different concentrations, / ¼ 0.15%, 0.48%, and 0.59% (w/v) [g/ml%] and exposed to uniform magnetic fields in the range of H ¼ 0.05-0.42 T. Cryogenic transmission electron microscopy is employed to provide in-situ observations of the field-induced assemblies in such systems. As the magnetic field increases, the Brownian colloids are observed to form randomly distributed chains aligned in the field direction, followed by head-to-tail chain aggregation and then lateral aggregation of chains termed as zippering. By increasing the field in low concentration samples, the number of chains increases, though their length does not change dramatically. Increasing concentration increases the length of the linear particle assemblies in the presence of a fixed external magnetic field. Thickening of the chains due to zippering is observed at relatively high fields. Through a systematic variation of concentration and magnetic field strength, this study shows that both magnetic field strength and change in concentration can strongly influence formation of microstructures even in weak dipolar systems. Additionally, the results of two commonly used support films on electron microscopy grids, continuous carbon and holey carbon films, are compared. Holey carbon film allows us to create local regions of high concentrations that further assist the development of field-induced assemblies. The experimental observations provide a validation of the zippering effect and can be utilized in the development of models for thermophysical properties such as thermal conductivity. V C 2015 AIP Publishing LLC.

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Equilibrium properties of ferrocolloids

Cited by 195 publications

References 19 publications

Theory and simulation of anisotropic pair correlations in ferrofluids in magnetic fields

Theory and simulation of anisotropic pair correlations in ferrofluids in magnetic fields

Magnetic Properties of Colloidal Suspensions of Interacting Magnetic Particles

Direct observations of field-induced assemblies in magnetite ferrofluids

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