Ferrofluids
Mostrando 1-12 de 14 artigos, teses e dissertações.
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1. Investigação da ordem local de nanocolóides magnéticos por espalhamento em baixo ângulo
In this work, we investigate using small angle scattering measurements the colloidal stability and the local order (typically between 10 nm and 100 nm) of magnetic nanocoloides, made of solution of magnetic ferrite nanospheres and mixed systems of magnetic nanospheres and laponite nanoplatelets. The balance of interparticles interactions has been quantitativ
Publicado em: 2009
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2. Rotational dynamics of the magnetic moments in ferrofluids
Publicado em: 2007
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3. Estudo das propriedades estruturais locais de fluidos magnéticos : da nanopartícula à dispersão
Local structural properties of magnetic fluids based on nanosized particles of zinc, copper or nickel ferrite are investigated. Nanograins prepared by a soft chemistry method are dispersed in acidic medium thanks to a core-shell strategy that prevents the particles from dissolution. Their chemical composition is no longer homogeneous and they can be describe
Publicado em: 2007
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4. "Caracterização estrutural e óptica de elastômeros dopados com ferrofluidos" / Optical and Structural Characterization of Elastomers Dopeds with Ferrofluids
This work aims the structural, mechanical and optical characterization of urethane/urea elastomers (PU/PBDO), based on polypropylene oxide and polybutadiene diol, pure, after swelling in toluene and doped with ferrofluid. The ratios in weight % of PU and PBDO used are 40/60, 50/50, 60/40 and 80/20. The structural analysis were made through of polarized light
Publicado em: 2007
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5. Computer simulation of the stochastic dynamics of super-paramagnetic particles in ferrofluids
Several papers have been written on the complex problem of the stochastic dynamics of the magnetic moments of super-paramagnetic particles, simultaneously with the stochastic rotation of these colloidal particles in a ferrofluid [1-3]. None of these works, however, is sufficiently general and conveniently simple and clear to be used in sumulational works to
Brazilian Journal of Physics. Publicado em: 2006-09
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6. Ferrofluids: properties and applications
Magnetic fluids may be classified as ferrofluids (FF), which are colloidal suspensions of very fine (~ 10 nm) magnetic particles, and magnetorheological fluids, which are suspensions of larger, usually non-stable, magnetic particles. We review the general classification and the main properties of FF, some theoretical models and a few applications. We conside
Brazilian Journal of Physics. Publicado em: 2005-09
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7. Stochastic Molecular Dynamics of colloidal particles
Colloidal particles move in the carrier liquid under the action of several forces and torques. When the particles carry a dipole moment, electric or magnetic, as in ferrofluids, the rotational and translational motions are coupled because the field on a particle depends on the spatial and directional distribution of the others and the force and torque on it
Brazilian Journal of Physics. Publicado em: 2004-06
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8. Lyotropic ferronematic liquid crystals based on new Ni, Cu and Zn Ionic magnetic fluids
The properties of lyotropic ferronematic liquid crystals based on new Ni, Cu and Zn ionic magnetic fluids are discussed. The efficiency of these new ferrofluids in the lyotropic nematic liquid crystal doping is verified and compared with the conventional surfacted ferro fluid lyotropic doping. It was observed that the structural characteristics of the lyotro
Brazilian Journal of Physics. Publicado em: 2002-06
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9. Mössbauer spectroscopy, superparamagnetism and ferrofluids
Some fundamentals of Mössbauer spectroscopy and of fluctuating magnetic hyperfine interactions are reviewed. An expression for calculation of spin-phonon interaction transition probabilities on the ground of a Debye model is given. Basic ideas of superparamagnetism and classical results for low-temperature relaxation rates are presented. A theory of superpa
Braz. J. Phys.. Publicado em: 2001-09
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10. Rotational dynamics of the magnetic moments in ferrofluids
We present a set of six non-linear stochastic diffferential equations for the six variables which are relevant for the dynamical behavior of the magnetic moments in ferrofluids, namely, the three Euler angles of the magnetic particle, the two polar angles of the magnetic moment relative to the particle and the modulus of the magnetic moment. The interaction
Braz. J. Phys.. Publicado em: 2001-09
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11. The effect of the ferrofluid magnetic particle concentration on the thermal diffusivity
Thermal diffusivity results obtained with the collinear mirage technique, are reported for different concentrations surfacted ferrofluid and for a set of acid ferrofluids with variable pH values. The collinear mirage technique was used because the materials are semitransparent and have low thermal diffusivities. The results show that, as the ferrofluid magne
Braz. J. Phys.. Publicado em: 2001-09
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12. Interfacial instabilities in confined ferrofluids
We investigate the flow of two immiscible, viscous fluids in the confined geometry of a Hele-Shaw cell. We consider that one of the fluids is a ferrofluid and that an external magnetic field is applied. The interfacial instabilities which arise between the fluids are studied for various situations: (a) different cell geometries (radial, rectangular); (b) fro
Braz. J. Phys.. Publicado em: 2001-09