Simulation of Wasp-Waisted Magnetic Hysteresis Loop for NiCoP-Coated BaFe12O19–Polystyrene Bilayer Composite Film
04 Jun 2016-Journal of Superconductivity and Novel Magnetism (Springer US)-Vol. 29, Iss: 9, pp 2451-2453
TL;DR: In this article, the authors modified the Brillouin function to model the wasp-waisted magnetic hysteresis loop for soft-magnetic NiCoP-coated hardmagnetic M-type ferrite BaFe12O19 polystyrene (PS) bilayer composite film taking into account the effective applied magnetic field due to localized impurity phases.
Abstract: Brillouin function was modified to model the wasp-waisted magnetic hysteresis loop for soft-magnetic NiCoP-coated hard-magnetic M-type ferrite BaFe12O19 polystyrene (PS) bilayer composite film taking into account the effective applied magnetic field due to localized impurity phases and significant change in the azimuthal angle of the magnetic moment due to the formation of bilayer structure of film by the addition of PS. It is shown that there is a good fit to the experimental data observed in wasp-waisted magnetic hysteresis loop. The analysis shows that the forward magnetization and reversal process are typical.
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241 citations
TL;DR: In this paper, polymeric composites based on room-temperature vulcanized (RTV) silicon rubber incorporated with different NiCr0.2Fe1.8O4 (NCF) content are prepared.
Abstract: In this work, polymeric composites based on room-temperature vulcanized (RTV) silicon rubber incorporated with different NiCr0.2Fe1.8O4 (NCF) content are prepared. The results indicate the well dispersion of various micron-sized particles of NCF with low agglomerations. The decrease in the density is the most advantage property that allows us to obtain the light magnetic material for industrial applications. It is shown that the rubber occupies the porous and defects between NCF particles. It is found that dielectric constant is enhanced with RTV content and decreases with increasing selected frequency for all samples. The electrical conductivity of composite is enhanced with both RTV content and the heat treatment temperature of composites. The saturation magnetization is strongly dependent on NCF content in RTV matrix.
20 citations
TL;DR: In this article, the effect of Zn content on magnetocaloric effect (MCE) in Pb(Zr0.52Ti0.48)O3-Ni(1−x)ZnxFe2O4 (PZT-NZF) with x ǫ = 0, 0.20, 0., 30, 0, 40, and 0.50 were investigated by phenomenological model.
Abstract: The effect of Zn content on magnetocaloric effect (MCE) in Pb(Zr0.52Ti0.48)O3–Ni(1−x)ZnxFe2O4 (PZT-NZF) with x = 0, 0.20, 0.30, 0.40 and 0.50 were investigated by phenomenological model. The results show that MCE for PZT-NZF is enhanced with low Zn content. However, for high Zn content samples, MCE for PZT-NZF decreases with Zn. In addition, MCE in PZT-NZF is tunable with Zn content and extends in highly temperature range. It is recommended that that MCE in PZT-NZF is beneficial for magnetic refrigeration for in high temperature.
19 citations
TL;DR: In this paper, the magnetocaloric properties of Ni0.5Cu0.25Zn0.4 (NCZFO) nanoferrite samples were simulated by phenomenological model and the results indicated that MC properties of NCZFO nanoferrites change none monotonically with annealing temperature.
Abstract: The magnetocaloric (MC) properties of Ni0.5Cu0.25Zn0.25Fe2O4 (NCZFO) nanoferrite samples prepared under different annealing temperatures were simulated by phenomenological model. The results indicate that MC properties of NCZFO nanoferrites change none monotonically with annealing temperature. Furthermore, the range of temperatures between 407 and 515 K are suitable for NCZFO nanoferrites to be used as an effective material in magnetic refrigeration (MR). It is concluded that NCZFO nanoferrites are very practical MC materials in MR for high temperature applications like automotive, aerospace, and food industries.
17 citations
TL;DR: The effect of trivalent ions (Al3+, Bi3+, and Mn3+) substitutions on magnetocaloric effect (MCE) of M-type ferrite BaFe12O19 (BaM) has been investigated by a phenomenological model as discussed by the authors.
Abstract: The effect of trivalent ions (Al3+, Bi3+, and Mn3+) substitutions on magnetocaloric effect (MCE) of M-type ferrite BaFe12O19 (BaM) has been investigated by a phenomenological model. It is shown that the presence of Al3+, Bi3+, and Mn3+ ions in BaM makes remarkable variations for MCE. It is concluded that MnBaFe11O19 is more practical than BaM, BiBaFe11O19, and AlBaFe11O19 due to a larger MCE, and its Curie temperature is closer to room temperature. MCE of BaM can be tuning with remarkable values by doping suitable ions.
17 citations
References
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23,110 citations
Book•
01 Jan 1953
TL;DR: In this paper, the Hartree-Fock Approximation of many-body techniques and the Electron Gas Polarons and Electron-phonon Interaction are discussed.
Abstract: Mathematical Introduction Acoustic Phonons Plasmons, Optical Phonons, and Polarization Waves Magnons Fermion Fields and the Hartree-Fock Approximation Many-body Techniques and the Electron Gas Polarons and the Electron-phonon Interaction Superconductivity Bloch Functions - General Properties Brillouin Zones and Crystal Symmetry Dynamics of Electrons in a Magnetic Field: de Haas-van Alphen Effect and Cyclotron Resonance Magnetoresistance Calculation of Energy Bands and Fermi Surfaces Semiconductor Crystals I: Energy Bands, Cyclotron Resonance, and Impurity States Semiconductor Crystals II: Optical Absorption and Excitons Electrodynamics of Metals Acoustic Attenuation in Metals Theory of Alloys Correlation Functions and Neutron Diffraction by Crystals Recoilless Emission Green's Functions - Application to Solid State Physics Appendix: Perturbation Theory and the Electron Gas Index.
21,954 citations
TL;DR: For example, first-order reversal curves (FORC) diagrams as mentioned in this paper can be used to identify and discriminate between the different components in a mixed magnetic mineral assemblage, such as superparamagnetic, single-domain, and multidomain grains.
Abstract: Paleomagnetic and environmental magnetic studies are commonly conducted on samples containing mixtures of magnetic minerals and/or grain sizes. Major hysteresis loops are routinely used to provide information about variations in magnetic mineralogy and grain size. Standard hysteresis parameters, however, provide a measure of the bulk magnetic properties, rather than enabling discrimination between the magnetic components that contribute to the magnetization of a sample. By contrast, first-order reversal curve (FORC) diagrams, which we describe here, can be used to identify and discriminate between the different components in a mixed magnetic mineral assemblage. We use magnetization data from a class of partial hysteresis curves known as first-order reversal curves (FORCs) and transform the data into contour plots (FORC diagrams) of a two-dimensional distribution function. The FORC distribution provides information about particle switching fields and local interaction fields for the assemblage of magnetic particles within a sample. Superparamagnetic, single-domain, and multidomain grains, as well as magnetostatic interactions, all produce characteristic and distinct manifestations on a FORC diagram. Our results indicate that FORC diagrams can be used to characterize a wide range of natural samples and that they provide more detailed information about the magnetic particles in a sample than standard interpretational schemes which employ hysteresis data. It will be necessary to further develop the technique to enable a more quantitative interpretation of magnetic assemblages; however, even qualitative interpretation of FORC diagrams removes many of the ambiguities that are inherent to hysteresis data.
891 citations
TL;DR: In this paper, the authors discuss results of numerical simulations using the simplest of systems, the single-domain/superparamagnetic (SD/SP) system, and demonstrate that wasp-waisting and potbellies can be easily generated from populations of SD and SP grains.
Abstract: Because the response of a magnetic substance to an applied field depends strongly on the physical properties of the material, much can be learned by monitoring that response through what is known as a “magnetic hysteresis loop”. The measurements are rapid and quickly becoming part of the standard set of tools supporting paleomagnetic research. Yet the interpretation of hysteresis loops is not simple. It has become apparent that although classic “single-domain”, “pseudo-single-domain”, and “multidomain” loops described in textbooks occur in natural samples, loops are frequently distorted, having constricted middles (wasp-waisted loops) or spreading middles and slouching shoulders (potbellies). Such complicated loops are often interpreted in oversimplified ways leading to erroneous conclusions. The physics of the problem have been understood for nearly half a century, yet numerical simulations appropriate to geological materials are almost unavailable. In this paper we discuss results of numerical simulations using the simplest of systems, the single-domain/superparamagnetic (SD/SP) system. Examination of the synthetic hysteresis loops leads to the following observations: (1) Wasp-waisting and potbellies can easily be generated from populations of SD and SP grains. (2) Wasp-waisting requires an SP contribution that saturates quickly, resulting in a steep initial slope, and potbellies require low initial slopes (the SP contribution approaching saturation at higher fields). The approach to saturation is dependent on volume, hence the cube of grain diameter. Therefore there is a very strong dependence of hysteresis loop shape on the assumed threshold size. (3) We were unable to generate potbellies using an SP/SD threshold size as large as 30 nm, and wasp waists cannot be generated using a threshold size as small as 8 nm. The occurrence of both potbellies and wasp waists in natural samples is consistent with a room temperature threshold size of some 15 nm (±5). (4) Simulations using a threshold size of 15–20 nm with populations dominated by SP grain sizes, that is with a small number of SD grains, produce synthetic hysteresis loops consistent with measured hysteresis loops and transmission electron microscopic observations from submarine basaltic glass. (5) Simulations and measurements using two populations with distinct coercivity spectra can also generate wasp-waisted loops. A relatively straightforward analysis of the resulting loops can distinguish the latter case from wasp-waisting resulting from SP/SD behavior.
622 citations
TL;DR: In this paper, the enhanced low-field magnetocaloric effect (MCE) is simulated for La0.7Ca0.3MnO3 (LCMO) ceramics that were fabricated by fast sintering process with different Al2O3 contents.
Abstract: The enhanced low-field magnetocaloric effect (MCE) is simulated for La0.7Ca0.3MnO3 (LCMO) ceramics that were fabricated by fast sintering process with different Al2O3 contents. It is shown that LCMO exhibits magnetic entropy change (ΔS
M
) much more uniform than that of gadolinium. The results show that the peak in the MCE at the ferromagnetic to paramagnetic phase transition is improved as the sintering temperature decreases. Furthermore, the samples open up a new way in which to tune the intrinsic properties of mixed-valence manganites. Through these results, LCMO has some potential applications for magnetic refrigerants in an extended high-temperature range. It is suggested that the fast sintering process with different Al2O3 contents for LCMO is an efficient way to obtain a working material of an apparatus based on the active magnetic regenerator cycle that cools hydrogen gas.
47 citations