Optimized design of a high-power-density PM-assisted synchronous reluctance machine with ferrite magnets for electric vehicles

Directory of Open Access Journals (Sweden)

Liu Xiping

2017-06-01

Full Text Available This paper proposes a permanent magnet (PM-assisted synchronous reluctance machine (PMASynRM using ferrite magnets with the same power density as rareearth PM synchronous motors employed in Toyota Prius 2010. A suitable rotor structure for high torque density and high power density is discussed with respect to the demagnetization of ferrite magnets, mechanical strength and torque ripple. Some electromagnetic characteristics including torque, output power, loss and efficiency are calculated by 2-D finite element analysis (FEA. The analysis results show that a high power density and high efficiency of PMASynRM are obtained by using ferrite magnets.

A combination of permanent magnet and magnetic coil for a large diameter ion source

International Nuclear Information System (INIS)

Uramoto, Joshin; Kubota, Yusuke; Miyahara, Akira.

1980-02-01

A large diameter ion source for fast neutral beam injection is designed under a magnetic field (we call ''Uramoto Field'') composed of a circular ferrite permanent magnet and a usual coreless magnetic coil. As the magnetic filed is reduced abruptly in a discharge anode, an ion source with a uniform ion current density over a large diameter is produced easily without a ''button'' of ORNL duoPIGatron type ion source (a floating electrode to diffuse an axial plasma flow radially). (author)

Structural investigation of chemically synthesized ferrite magnetic nanomaterials

Science.gov (United States)

Uyanga, E.; Sangaa, D.; Hirazawa, H.; Tsogbadrakh, N.; Jargalan, N.; Bobrikov, I. A.; Balagurov, A. M.

2018-05-01

In recent times, interest in ferrite magnetic nanomaterials has considerably grown, mainly due to their highly promising medical and biological applications. Spinel ferrite powder samples, with high heat generation abilities in AC magnetic fields, were studied for their application to the hyperthermia treatment of cancer tumors. These properties of ferrites strongly depend on their chemical composition, ion distribution between crystallographic positions, magnetic structure and method of preparation. In this study, crystal and magnetic structures of several magnetic spinels were investigated by neutron diffraction. The explanation of the mechanism triggering the heat generation ability in the magnetic materials, and the electronic and magnetic states of ferrite-spinel type structures, were theoretically defined by a first-principles method. Ferrites with the composition of CuxMg1-xFe2O4 have been investigated as a heat generating magnetic nanomaterial. Atomic fraction of copper in ferrite was varied between 0 and 100% (that is, x between 0 and 1.0 with 0.2 steps), with the copper dope limit corresponding to appear a tetragonal phase.

Current status and future outlook for bonded neodymium permanent magnets (invited)

International Nuclear Information System (INIS)

Croat, J.J.

1997-01-01

Bonded neodymium magnets can provide significant size and weight reduction and/or performance enhancement over sintered and, particularly, bonded ferrite permanent magnets and, moreover, provide these benefits at reasonable cost. Primarily for these reasons, these bonded magnets are now used in a wide and growing range of computer peripheral, office automation, and consumer electronic applications and now constitute the fastest growing segment of the permanent magnet market. The current status of these materials will be reviewed. Included is a brief overview of the manufacture of these magnetically isotropic magnets and a discussion of their unique properties and features from the perspective of both bonded magnet producer and user. Major applications are discussed as are some of the factors that will drive the market for these materials in the future. New technical developments, including the status and outlook for anisotropic bonded materials, high remanance isotropic materials and high temperature bonded magnets will also be discussed. copyright 1997 American Institute of Physics

Study on Magnetic Responsibility of Rare Earth Ferrite/Polyacrylamide Magnetic Microsphere

Institute of Scientific and Technical Information of China (English)

Zhang Ming; Wang Zhifeng; Zhang Hong; Dai Shaojun; Qiu Guanming; Okamoto Hiroshi

2005-01-01

In inverse microemulsion, rare earth ferrite/polyacrylamide magnetic microsphere were prepared and their magnetic responsibility were studied by magnetic balance. Results indicate that the magnetic responsibility of microsphere relates to magnetic moment of rare earth ion, and it can be improved by the addition of dysprosium ion of high magnetic moment. Dysprosium content has an effect on magnetic responsibility of dysprosium ferrite/polyacrylamide magnetic microsphere. The microsphere displays strong magnetic responsibility when the molar ratio of Dy3+/iron is 0.20.

Hybrid permanent magnet quadrupoles for the Recycler Ring at Fermilab

International Nuclear Information System (INIS)

Brown, B.C.; Pruss, S.M.; Foster, G.W.; Glass, H.D.; Harding, D.J.; Jackson, G.R.; May, M.R.; Nicol, T.H.; Ostiguy, J.-F.; Schlabach, R.; Volk, J.T.

1997-10-01

Hybrid Permanent Magnet Quadrupoles are used in several applications for the Fermilab Recycler Ring and associated beam transfer lines. Most of these magnets use a 0.6096 m long iron shell and provide integrated gradients up to 1.4 T-m/m with an iron pole tip radius of 41.6 mm. A 58.4 mm pole radius design is also required. Bricks of 25. 4 mm thick strontium ferrite supply the flux to the back of the pole to produce the desired gradients (0.6 to 2.75 T/m). For temperature compensation, Ni-Fe alloy strips are interspersed between ferrite bricks to subtract flux in a temperature dependent fashion. Adjustments of the permeance of each pole using iron between the pole and the flux return shell permits the matching of pole potentials. Magnetic potentials of the poles are adjusted to the desired value to achieve the prescribed strength and field uniformity based on rotating coil harmonic measurements. Procurement, fabrication, pole potential adjustment, and measured fields will be reported

Performance Variation of Ferrite Magnet PMBLDC Motor with Temperature

DEFF Research Database (Denmark)

Fasil, Muhammed; Mijatovic, Nenad; Jensen, Bogi Bech

2015-01-01

The price fluctuations of rare earth metals and the uncertainty in their availability has generated an increased interest in ferrite magnet machines. The influence of temperature on BH characteristics of the ferrite magnet differ considerably from that of the rare earth magnet and hence, requires...

Permanent quadrupole magnets

International Nuclear Information System (INIS)

Bush, E.D. Jr.

1976-01-01

A family of quadrupole magnets using a soft iron return yoke and circular cross-section permanent magnet poles were fabricated to investigate the feasibility for use in ion or electron beam focusing applications in accelerators and transport lines. Magnetic field measurements yielded promising results. In fixed-field applications, permanent magnets with sufficient gradients would be a low cost substitute for conventional electromagnets, eliminating the need for power supplies, associated wiring, and cooling. Based on preliminary tests, it was seen that permanent quadrupole magnets can offer a low cost, reliable solution in applications requiring small, fixed-field focusing devices for use in ion or electron-beam transport systems. Permanent magnets do require special considerations in design, fabrication, handling, and service that are different than encountered in conventional quadrupole magnets. If these basic conditions are satisfied, the resulting beam-focusing device would be stable, maintenance free, with virtually an indefinite lifetime

Surface effects on the magnetic behavior of nanocrystalline nickel ferrites and nickel ferrite-polymer nanocomposites

International Nuclear Information System (INIS)

Nathani, H.; Misra, R.D.K.

2004-01-01

The magnetization studies on nanocrystalline nickel ferrite as powder particles, and as diluted dispersion (10 wt.%) in polymer matrix (polymer nanocomposites) are presented. The two polymer-based nanocomposites were prepared via ball-milling and in situ polymerization, respectively. The magnetization measurements provide strong evidence of surface effects to magnetization, which explains the non-saturation of magnetization at high fields. The differences in the magnetization behavior of nickel ferrite as powder particles and in the ball-milled nanocomposite and the nanocomposite prepared via in situ polymerization are attributed to the different extent of interparticle interactions between the particles and the preparation route. The magnetization versus applied field behavior of the three ferrite systems show a similar jump in the initial part of the magnetization curve in all the cases which implies the existence of a core-shell like morphology of the particles over a large temperature range and its dominance over the interparticle interaction effects between the particles

Dense arrays of cobalt nanorods as rare-earth free permanent magnets.

Science.gov (United States)

Anagnostopoulou, E; Grindi, B; Lacroix, L-M; Ott, F; Panagiotopoulos, I; Viau, G

2016-02-21

We demonstrate in this paper the feasibility to elaborate rare-earth free permanent magnets based on cobalt nanorods assemblies with energy product (BH)max exceeding 150 kJ m(-3). The cobalt rods were prepared by the polyol process and assembled from wet suspensions under a magnetic field. Magnetization loops of dense assemblies with remanence to a saturation of 0.99 and squareness of 0.96 were measured. The almost perfect M(H) loop squareness together with electron microscopy and small angle neutron scattering demonstrate the excellent alignment of the rods within the assemblies. The magnetic volume fraction was carefully measured by coupling magnetic and thermogravimetric analysis and found in the range from 45 to 55%, depending on the rod diameter and the alignment procedure. This allowed a quantitative assessment of the (BH)max values. The highest (BH)max of 165 kJ m(-3) was obtained for a sample combining a high magnetic volume fraction and a very large M(H) loop squareness. This study shows that this bottom-up approach is very promising to get new hard magnetic materials that can compete in the permanent magnet panorama and fill the gap between the ferrites and the NdFeB magnets.

Calcium ferrite formation from the thermolysis of calcium tris (maleato)

Indian Academy of Sciences (India)

microwave and satellite communication, bubble devices, audio-video, digital recording and as permanent magnets. (Viswanathan and Murthy 1990), ferrites have opened a new vista in the field of chemical physics of materials. Keeping in view these technological applications, ferrites have been regarded as an important ...

A study of the suitability of ferrite for use in low-field insertion devices

Energy Technology Data Exchange (ETDEWEB)

Johnson, K.; Hassenzahl, W.V.

1995-02-01

Most insertion devices built to date use rare-earth permanent-magnet materials, which have a high remanent field and are more expensive than many other permanent-magnet materials. Low-field insertion devices could use less-expensive, lower performance magnetic materials if they had suitable magnetic characteristics. These materials must be resistant to demagnetization during construction and operation of the insertion device, have uniform magnetization, possess low minor-axis magnetic moments, and have small minor field components on the surfaces. This paper describes an investigation to determine if ferrite possesses magnetic qualities suitable for insertion device applications. The type of ferrite investigated, MMPA Ceramic 8 from Stackpole Inc., was found to be acceptable for insertion device applications.

The role of cobalt ferrite magnetic nanoparticles in medical science

International Nuclear Information System (INIS)

Amiri, S.; Shokrollahi, H.

2013-01-01

The nanotechnology industry is rapidly growing and promises that the substantial changes that will have significant economic and scientific impacts be applicable to a wide range of areas, such as aerospace engineering, nano-electronics, environmental remediation and medical healthcare. In this area, cobalt ferrite nanoparticles have been regarded as one of the competitive candidates because of their suitable physical, chemical and magnetic properties like the high anisotropy constant, high coercivity and high Curie temperature, moderate saturation magnetization and ease of synthesis. This paper introduces the magnetic properties, synthesis methods and some medical applications, including the hyperthermia, magnetic resonance imaging (MRI), magnetic separation and drug delivery of cobalt ferrite nanoparticles. Highlights: ► Cobalt ferrite nanoparticles are one of the most important materials for nanomedicine. ► They have high coercivity and moderate saturation magnetization. ► Cobalt ferrite nanoparticles are synthesized easily. ► They are a good candidate for hyperthermia and magnetic resonance imaging.

The role of cobalt ferrite magnetic nanoparticles in medical science

Energy Technology Data Exchange (ETDEWEB)

Amiri, S.; Shokrollahi, H., E-mail: Shokrollahi@sutech.ac.ir

2013-01-01

The nanotechnology industry is rapidly growing and promises that the substantial changes that will have significant economic and scientific impacts be applicable to a wide range of areas, such as aerospace engineering, nano-electronics, environmental remediation and medical healthcare. In this area, cobalt ferrite nanoparticles have been regarded as one of the competitive candidates because of their suitable physical, chemical and magnetic properties like the high anisotropy constant, high coercivity and high Curie temperature, moderate saturation magnetization and ease of synthesis. This paper introduces the magnetic properties, synthesis methods and some medical applications, including the hyperthermia, magnetic resonance imaging (MRI), magnetic separation and drug delivery of cobalt ferrite nanoparticles. Highlights: Black-Right-Pointing-Pointer Cobalt ferrite nanoparticles are one of the most important materials for nanomedicine. Black-Right-Pointing-Pointer They have high coercivity and moderate saturation magnetization. Black-Right-Pointing-Pointer Cobalt ferrite nanoparticles are synthesized easily. Black-Right-Pointing-Pointer They are a good candidate for hyperthermia and magnetic resonance imaging.

Tailoring the magnetic properties of cobalt-ferrite nanoclusters

Energy Technology Data Exchange (ETDEWEB)

Vega, A. Estrada de la; Garza-Navarro, M. A., E-mail: marco.garzanr@uanl.edu.mx; Durán-Guerrero, J. G.; Moreno Cortez, I. E.; Lucio-Porto, R.; González-González, V. [Universidad Autónoma de Nuevo León, Facultad de Ingeniería Mecánica y Eléctrica (Mexico)

2016-01-15

In this contribution, we report on the tuning of magnetic properties of cobalt-ferrite nanoclusters. The cobalt-ferrite nanoclusters were synthesized from a two-step approach that consists of the synthesis of cobalt-ferrite nanoparticles in organic media, followed by their dispersion into aqueous dissolution to form an oil-in-water emulsion. These emulsions were prepared at three different concentrations of the cationic surfactant cetyltrimethylammonium bromide (CTAB), in order to control the size and clustering density of the nanoparticles in the nanoclusters. The synthesized samples were characterized by transmission electron microscopy and their related techniques, such as bright-field and Z-contrast imaging, electron diffraction and energy-dispersive X-ray spectrometry; as well as static magnetic measures. The experimental evidence indicates that the size, morphology, and nanoparticles clustering density in the nanoclusters is highly dependent of the cobalt-ferrite:CTAB molar ratio that is used in their synthesis. In addition, due to the clustering of the nanoparticles into the nanoclusters, their magnetic moments are blocked to relax cooperatively. Hence, the magnetic response of the nanoclusters can be tailored by controlling the size and nanoparticles clustering density.

A Complete Design of a Rare Earth Metal-Free Permanent Magnet Generator

Directory of Open Access Journals (Sweden)

Petter Eklund

2014-05-01

Full Text Available The price of rare-earth metals used in neodymium-iron-boron (NdFeB permanent magnets (PMs has fluctuated greatly recently. Replacing the NdFeB PMs with more abundant ferrite PMs will avoid the cost insecurity and insecurity of supply. Ferrite PMs have lower performance than NdFeB PMs and for similar performance more PM material has to be used, requiring more support structure. Flux concentration is also necessary, for example, by a spoke-type rotor. In this paper the rotor of a 12 kW NdFeB PM generator was redesigned to use ferrite PMs, reusing the existing stator and experimental setup. Finite element simulations were used to calculate both electromagnetic and mechanical properties of the design. Focus was on mechanical design and feasibility of construction. The result was a design of a ferrite PM rotor to be used with the old stator with some small changes to the generator support structure. The new generator has the same output power at a slightly lower voltage level. It was concluded that it is possible to use the same stator with either a NdFeB PM rotor or a ferrite PM rotor. A ferrite PM generator might require a larger diameter than a NdFeB generator to generate the same voltage.

Comparison of torque capability of three-phase permanent magnet synchronous motors with different permanent magnet arrangement

International Nuclear Information System (INIS)

Stumberger, Bojan; Stumberger, Gorazd; Hadziselimovic, Miralem; Hamler, Anton; Gorican, Viktor; Jesenik, Marko; Trlep, Mladen

2007-01-01

The paper presents a comparison of torque capability of three-phase permanent magnet synchronous motors with different permanent magnet arrangement. Motors with the following permanent magnet topologies were accounted for in the comparison: the surface-mounted permanent magnet synchronous motor (SMPMSM), the interior permanent magnet synchronous motor (IPMSM), the permanent magnet-assisted synchronous reluctance motor (PMASRM) and the flux reversal permanent magnet motor (FRPMM). Finite element method analysis is employed to determine the performance of each motor. Calculated performance of four-pole IPMSM determined by finite element method calculation is confirmed with the measurements at nearly constant nominal output power in the range of speed 3000-10,000 rpm

3-D analysis of eddy current in permanent magnet of interior permanent magnet motors

International Nuclear Information System (INIS)

Kawase, Yoshihiro; Yamaguchi, Tadashi; Fukanaga, Hiromu; Ito, Shokichi

2002-01-01

Interior permanent magnet motors are widely used in various fields. However, in high-speed operations, it is important to decrease the eddy current loss in the permanent magnet. In order to decrease the eddy current loss, we propose to divide the permanent magnet. In this paper, we clarified the effect of division of permanent magnet on the eddy current loss using the 3-D finite element method. (Author)

Hybrid permanent magnet gradient dipoles for the recycler ring at Fermilab

International Nuclear Information System (INIS)

Brown, B.C.; Dimarco, J.; Foster, G.W.; Glass, H.D.; Haggard, J.E.; Harding, D.J.; Jackson, G.R.; May, M.R.; Nicol, T.H.; Ostiguy, J.-F.; Schlabach, R.; Volk, J.T.

1997-11-01

Hybrid permanent magnets provide the magnetic fields for an anti- proton storage ring which is under construction at Fermilab. Using a combined function lattice, gradient magnets provide the bending, focusing and sextupole correction for the regular cells. Shorter magnets without sextupole are used in dispersion suppressor cells. These magnets use a 4.7 m ( 3 m) long iron shell for flux return, bricks of 25.4 mm thick strontium ferrite supply the flux and transversely tapered iron poles separated by aluminum spacers set the shape of the magnetic field. Central fields of 0.14 T with gradients of ∼6%/inch (∼13%/inch) are required. Field errors are expected to be less than 10 -4 of the bend field over an aperture of ±40 mm (horizontal) x ±20 mm (vertical). Design, procurement, fabrication, pole potential adjustment, field shape trimming and measured fields will be reported

Magnetic behavior of nanocrystalline nickel ferrite

International Nuclear Information System (INIS)

Nathani, H.; Gubbala, S.; Misra, R.D.K.

2005-01-01

In the previous papers [R.D.K. Misra, A. Kale, R.S. Srivatsava, O. Senkov, Mater. Sci. Technol. 19 (2003) 826; R.D.K. Misra, A. Kale, B. Hooi, J.Th. DeHosson, Mater. Sci. Technol. 19 (2003) 1617; A. Kale, S. Gubbala, R.D.K. Misra, J. Magn. Magn. Mater. 277 (2004) 350; S. Gubbala, H. Nathani, K. Koizol, R.D.K. Misra, Phys. B 348 (2004) 317; R.D.K. Misra, S. Gubbala, A. Kale, W.F. Egelhoff, Mater. Sci. Eng. B. 111 (2004) 164], we reported the synthesis, structural characterization and magnetic behavior of nanocrystalline ferrites of inverse and mixed spinel structure made by reverse micelle technique that enabled a narrow particle size distribution to be obtained. In the present paper, the reverse micelle approach has been extended to synthesize nanocrystalline ferrites with varying surface roughness of 8-18 A (the surface roughness was measured by atomic force microscopy) and the magnetic behavior studied by SQUID magnetometer. Two different kinds of measurement were performed: (a) zero-field cooling (ZFC) and field cooling (FC) magnetization versus temperature measurements and (b) magnetization as a function of applied field. The analysis of magnetic measurement suggests significant influence of surface roughness of particles on the magnetic behavior. While the superparamagnetic behavior is retained by the nanocrystalline ferrites of different surface roughness at 300 K, the hysteresis loop at 2 K becomes non-squared and the coercivity increases with increase in surface roughness. This behavior is discussed in terms of broken bonds and degree of surface spin disorder

Beam impedance of ferrite kicker magnets

International Nuclear Information System (INIS)

Voelker, F.; Lambertson, G.

1989-03-01

We have measured the longitudinal beam impedance of a typical pulsed magnet that will be used in the Advanced Light Source. The magnets are of a ferrite window-frame design with a single plate conductor on each side. Two separate power supplies are used to drive current in opposite directions in the two conductors. The continuity of the ferrite yoke is interrupted by two copper plates 1 mm thick in the center of the top and bottom of the window frame. This increases the reluctance of the magnetic path, and thus decreases the flux which couples the beam. The measurements were made by exciting a 1/8'' rod along the beam path through the magnet. This makes a 185 ohm transmission line, and it was terminated in a resistive divider at the exit end. A 3 GHz network analyzer was used to measure S 21 through the magnet, and longitudinal beam impedance was calculated from this data. The impedance is dominated by two low frequency resonances in the magnet winding and drive current. 8 figs

Microstructural evaluation and magnetic Ni-Zn ferrite sintered by microwave energy

International Nuclear Information System (INIS)

Diniz, Veronica Cristhina S.; Vieira, Debora A.; Costa, Ana Cristina F.M.; Kiminami, R.H.G.A.; Cornejo, Daniel Reinaldo

2011-01-01

The present Ni-Zn ferrite magnetic properties sensitive to microstructure and obtain a ferrite with a uniform microstructure is the biggest challenge in the advancement of new technologies. This study proposes to evaluate the microstructure and magnetic properties of Ni-Zn ferrite sintered by microwave energy. The samples were previously synthesized by combustion reaction using urea and glycine, with 1200 deg C/2h sintered at a heating rate of 5 deg C/min, and characterized by density, XRD, SEM and magnetic measurements. The results show that the sample synthesized with glycine showed the formation of ferrite phase and traces of secondary phase hematite, grains with undefined format, and a high porosity and inter intragranular. The sample synthesized with urea gave only the ferrite phase, with hexagonal grains, and low intergranular porosity. The sample synthesized with urea showed better magnetic characteristics when compared with the samples synthesized with glycine. (author)

Permanent quadrupole magnets

International Nuclear Information System (INIS)

Bush, E.D. Jr.

1976-01-01

A family of quadrupole magnets using a soft iron return yoke and circular cross-section permanent magnet poles were fabricated to investigate the feasibility for use in ion or electron beam focusing applications in accelerators and transport lines. Magnetic field measurements yielded promising results. In fixed-field applications, permanent magnets with sufficient gradients would be a low cost substitute for conventional electromagnets, eliminating the need for power supplies, associated wiring, and cooling. (author)

Magnetic and Structural Investigations of Nanocrystalline Cobalt-Ferrite

Directory of Open Access Journals (Sweden)

I. Sharifi

2012-10-01

Full Text Available Cobalt ferrite is an important magnetic material due to their large magneto-crystalline anisotropy, high cohercivity, moderate saturation magnetization and chemical stability.In this study, cobalt ferrites Nanoparticles have been synthesized by the co-precipitation method and a new microemulsion route. We examined the cation occupancy in the spinel structure based on the “Rietveld with energies” method. The Xray measurements revealed the production of a broad single ferrite cubic phase with the average particle sizes of about 12 nm and 7nm, for co-precipitation and micro-emulsion methods, respectively. The FTIR measurements between 400 and 4000 cm-1 confirmed the intrinsic cation vibrations of the spinelstructure for the two methods. Furthermore, the Vibrating Sample Magnetometer (VSM was carried out at room temperature to study the structural and magnetic properties. The results revealed that by changing the method from co-precipitation to the reverse micelle the material exhibits a softer magnetic behavior in such a way that both saturation magnetization and coercivity decrease from 58 to 29 emu/g and from 286 to 25 Oe, respectively.

Laced permanent magnet quadrupole drift tube magnets

International Nuclear Information System (INIS)

Feinberg, B.; Behrsing, G.U.; Halbach, K.; Marks, J.S.; Morrison, M.E.; Nelson, D.H.

1988-10-01

A laced permanent magnet quadrupole drift tube magnet has been constructed for a proof-of-principle test. The magnet is a conventional tape-wound quadrupole electromagnet, using iron pole- pieces, with the addition of permanent magnet material (neodymium iron) between the poles to reduce the effects of saturation. The iron is preloaded with magnetic flux generated by the permanent magnet material, resulting in an asymmetrical saturation curve. Since the polarity of the quadrupole magnets in a drift tube linac is not reversed we can take advantage of this asymmetrical saturation to provide greater focusing strength. The magnet configuration has been optimized and the vanadium permendur poles needed in a conventional quadrupole have been replaced with iron poles. The use of permanent magnet material has allowed us to increase the focusing strength of the magnet by about 20% over that of a conventional tape-wound quadrupole. Comparisons will be made between this magnet and the conventional tape-wound quadrupole. 3 refs., 5 figs

Lithium ferrite: The study on magnetic and complex permittivity characteristics

Directory of Open Access Journals (Sweden)

Madhavaprasad Dasari

2017-03-01

Full Text Available Lithium ferrite (Li0.5Fe2.5O4 powder was prepared by solid state reaction method, which was finally pressed and sintered at 1150 °C. The spinel structure of the lithium ferrite was confirmed by X-ray diffraction and grain size estimation was obtained from scanning electron microscope (SEM. Fourier transform infrared spectroscopy (FTIR confirmed the presence of primary and secondary absorption bands characteristic for spinel structure. The force constants were estimated using absorption bands for the lithium ferrite. Magnetization and dielectric studies were carried out for the sintered sample. Saturation magnetization (Ms of 59.6 emu/g was achieved and variation of magnetization with temperature was used to identify the Curie temperature. The complex permittivity (ε∗ for the lithium ferrite sample was obtained for wide frequency range up to 3 GHz and discussed based on available models. The Curie temperature was estimated around 480 °C and verified from both magnetization versus temperature and dielectric constant versus temperature measurements.

Permanent magnets including undulators and wigglers

CERN Document Server

Bahrdt, J

2010-01-01

After a few historic remarks on magnetic materials we introduce the basic definitions related to permanent magnets. The magnetic properties of the most common materials are reviewed and the production processes are described. Measurement techniques for the characterization of macroscopic and microscopic properties of permanent magnets are presented. Field simulation techniques for permanent magnet devices are discussed. Today, permanent magnets are used in many fields. This article concentrates on the applications of permanent magnets in accelerators starting from dipoles and quadrupoles on to wigglers and undulators.

Generation of magnetic fields for accelerators with permanent magnets

International Nuclear Information System (INIS)

Meinander, T.

1994-01-01

Commercially available permanent magnet materials and their properties are reviewed. Advantages and disadvantages of using permanent magnets as compared to electromagnets for the generation of specific magnetic fields are discussed. Basic permanent magnet configurations in multipole magnets and insertion devices are presented. (orig.)

Magnetic guns with cylindrical permanent magnets

DEFF Research Database (Denmark)

Vokoun, David; Beleggia, Marco; Heller, Luděk

2012-01-01

The motion of a cylindrical permanent magnet (projectile) inside a tubular permanent magnet, with both magnets magnetized axially, illustrates nicely the physical principles behind the operation of magnetic guns. The force acting upon the projectile is expressed semi-analytically as derivative...... of the magnetostatic interaction energy. For comparison, the forces involved are also calculated numerically using finite elements methods. Based on the conservation of the magnetostatic and kinetic energies, the exit and asymptotic velocities are determined. The derived formulas can be used to optimize the generated...... forces and motion of the inner cylindrical magnet....

Structure and magnetic properties of granular NiZn-ferrite - SiO2

Directory of Open Access Journals (Sweden)

Albuquerque Adriana Silva de

1999-01-01

Full Text Available Granular systems composed by nanostructured magnetic materials embedded in a non-magnetic matrix present unique physical properties that depend crucially on their nanostructure. In this work, we have studied the structural and magnetic properties of NiZn-ferrite nanoparticles embedded in SiO2, a granular system synthesized by sol-gel processing. Samples with ferrite volumetric fraction x ranging from 6% to 78% were prepared, and characterized by X-ray diffraction, Mössbauer spectroscopy and vibrating sample magnetometry. Our results show the formation of pure stoichiometric NiZn-ferrite in the SiO2 matrix for x < 34%. Above these fraction, our samples presented also small amounts of Fe2O3. Mössbauer spectroscopy revealed the superparamagnetic behaviour of the ferrimagnetic NiZn-ferrite nanoparticles. The combination of different ferrite concentration and heat treatments allowed the obtaintion of samples with saturation magnetization between 1.3 and 68 emu/g and coercivity ranging from 0 to 123 Oe, value which is two orders of magnitude higher than the coercivity of bulk NiZn-ferrite.

Studies on magnetic properties of chemically synthesized crystalline calcium ferrite nanoparticles

Energy Technology Data Exchange (ETDEWEB)

Debnath, A., E-mail: debnathanimesh@gmail.com [Department of Civil Engineering, National Institute of Technology Agartala, Jirania, West Tripura, 799046 India (India); Bera, A.; Saha, B. [Department of Physics, National Institute of Technology Agartala, Jirania, West Tripura 799046 (India); Chattopadhyay, K. K. [Department of Physics, Jadavpur University, Kolkata 700 032 (India)

2016-05-23

Spinel-type ferrites have taken a very important role for modern electronic industry. Most of these ferrites exhibit low-loss dielectric properties, high resistivity, low eddy current and also high temperature ferromagnetism. Calcium ferrite is one such important metal oxide which is environmentally safe, chemically stable, low cost and greatly abundant. This outstanding material of calcium ferrite is synthesized by a simple chemical precipitation method using NaOH as the precipitating agent. Ferric chloride anhydrous (FeCl{sub 3}) and Calcium chloride dihydrate (CaCl{sub 2}.2H{sub 2}O) were used as iron and calcium sources respectively. The samples were heated at 200°C for 8h to obtain homogeneous powder of Calcium ferrite. The powders were characterized by using X-ray diffraction (XRD), field emission scanning electron microscope (FESEM), Transmission electrical microscopy (TEM), and Fourier transform infrared spectroscopic (FTIR) measurements. The polycrystalline nature of the sample was confirmed by X-ray diffraction study. The magnetic properties of the sample were investigated by vibrating sample magnetometer (VSM) measurements. Magnetization curve of the prepared sample depicts that as synthesized calcium ferrite nanoparticles have saturation magnetic moment of 1.74 emu/g and the coercivity of 35.08 Oe with superparamagnetic behavior. The synthesized calcium ferrite nanoparticles with such magnetic properties will be a candidate material for different applications in electronics and exploring its functionality in the field of recently developing semiconductor device physics and spintronics.

Studies on magnetic properties of chemically synthesized crystalline calcium ferrite nanoparticles

International Nuclear Information System (INIS)

Debnath, A.; Bera, A.; Saha, B.; Chattopadhyay, K. K.

2016-01-01

Spinel-type ferrites have taken a very important role for modern electronic industry. Most of these ferrites exhibit low-loss dielectric properties, high resistivity, low eddy current and also high temperature ferromagnetism. Calcium ferrite is one such important metal oxide which is environmentally safe, chemically stable, low cost and greatly abundant. This outstanding material of calcium ferrite is synthesized by a simple chemical precipitation method using NaOH as the precipitating agent. Ferric chloride anhydrous (FeCl_3) and Calcium chloride dihydrate (CaCl_2.2H_2O) were used as iron and calcium sources respectively. The samples were heated at 200°C for 8h to obtain homogeneous powder of Calcium ferrite. The powders were characterized by using X-ray diffraction (XRD), field emission scanning electron microscope (FESEM), Transmission electrical microscopy (TEM), and Fourier transform infrared spectroscopic (FTIR) measurements. The polycrystalline nature of the sample was confirmed by X-ray diffraction study. The magnetic properties of the sample were investigated by vibrating sample magnetometer (VSM) measurements. Magnetization curve of the prepared sample depicts that as synthesized calcium ferrite nanoparticles have saturation magnetic moment of 1.74 emu/g and the coercivity of 35.08 Oe with superparamagnetic behavior. The synthesized calcium ferrite nanoparticles with such magnetic properties will be a candidate material for different applications in electronics and exploring its functionality in the field of recently developing semiconductor device physics and spintronics.

Magnetic spring based on two permanent magnets

International Nuclear Information System (INIS)

Tsivilitsin, V.Yu.; Mil'man, Yu.V.; Goncharuk, V.A.; Bondar, I.B.

2011-01-01

A new type of the magnetic spring construction 'two permanent magnets' has been considered. A mathematical expression for the estimation of a pulling-in force has been offered. This expression is verified experimentally on the produced operating magnetic spring. The theoretical and experimental data are in good accordance. A number of advantages of the magnetic spring over the construction 'permanent magnet - magnetic circuit' such as an insignificant friction force between two magnets and a higher pulling force are discussed.

Testing of the permanent magnet material Mn-Al-C for potential use in propulsion motors for electric vehicles

Science.gov (United States)

Abdelnour, Z.; Mildrun, H.; Strant, K.

1981-01-01

The development of Mn-Al-C permanent magnets is reviewed. The general properties of the material are discussed and put into perspective relative to alnicos and ferrites. The traction motor designer's demands of a permanent magnet for potential use in electric vehicle drives are reviewed. Tests determined magnetic design data and mechanical strength properties. Easy axis hysteresis and demagnetization curves, recoil loops and other minor loop fields were measured over a temperature range from -50 to 150 C. Hysteresis loops were also measured for three orthogonal directions (the one easy and two hard axes of magnetization). Extruded rods of three different diameters were tested. The nonuniformity of properties over the cross section of the 31 mm diameter rod was studied. Mechanical compressive and bending strength at room temperature was determined on individual samples from the 31 mm rod.

Introduction to permanent magnets

International Nuclear Information System (INIS)

Zijlstra, H.

1985-01-01

Some general considerations concerning the application of permanent magnets are developed. The relevant magnet properties are discussed, with particular reference to Nd-Fe-B alloy. The author comes to the following conclusions; the air gap field B should be high, for high electrical efficiency; the magnet should face the air gap, for efficient use of the magnet material; the magnet material should therefore have a high remanence; and the new Nd-Fe-B magnet fits in nicely, having (potentially) the highest remanence ever reported in permanent magnets, combined with sufficient coercivity to sustain it

Magnetoabsorption and magnetic hysteresis in Ni ferrite nanoparticles

Directory of Open Access Journals (Sweden)

Torres C.

2013-01-01

Full Text Available Nickel ferrite nanoparticles were prepared by a modified sol-gel technique employing coconut oil, and then annealed at different temperatures in 400-1200 °C range. This route of preparation has revealed to be one efficient and cheap technique to obtain high quality nickel ferrite nanosized powder. Sample particles sizes obtained with XRD data and Scherrer’s formula lie in 13 nm to 138 nm, with increased size with annealing temperature. Hysteresis loops have been obtained at room temperature with an inductive method. Magnetic field induced microwave absorption in nanoscale ferrites is a recent an active area of research, in order to characterize and explore potential novel applications. In the present work microwave magnetoabsorption data of the annealed nickel ferrite nanoparticles are presented. These data have been obtained with a system based on a network analyzer that operates in the frequency range 0 - 8.5 GHz. At fields up to 400 mT we can observe a peak according to ferromagnetic resonance theory. Sample annealed at higher temperature exhibits different absorption, coercivity and saturation magnetization figures, revealing its multidomain character.

Path E alloys: ferritic material development for magnetic fusion energy applications

International Nuclear Information System (INIS)

Holmes, J.J.

1980-09-01

The application of ferritic materials in irradiation environments has received greatly expanded attention in the last few years, both internationally and in the United States. Ferritic materials are found to be resistant to irradiation damage and have in many cases superior properties to those of AISI 316. It has been shown that for magnetic fusion energy applications the low thermal expansion behavior of the ferritic alloy class will result in lower thermal stresses during reactor operation, leading to significantly longer ETF operating lifetimes. The Magnetic Fusion Energy Program therefore now includes a ferritic alloy option for alloy selection and this option has been designated Path E

X-ray and magnetic studies of Zn substituted Ni–Pb ferrites

Indian Academy of Sciences (India)

Unknown

nic applications such as transformers, choke coils, noise filters, recording heads etc. Nickel ferrites and Zn2+ sub- stituted nickel-ferrites are widely used in electronics and electrical industries as they exhibit interesting variations in the electrical and magnetic properties. Electrical and magnetic properties are influenced by ...

Ferritic insertion for reduction of toroidal magnetic field ripple on JT-60U

International Nuclear Information System (INIS)

Shinohara, K.; Sakurai, S.; Ishikawa, M.; Tsuzuki, K.; Suzuki, Y.; Masaki, K.; Naito, O.; Kurihara, K.; Suzuki, T.; Koide, Y.; Fujita, T.; Miura, Y.

2007-01-01

Ferritic steel tiles (FSTs) have been installed to improve the energetic ion confinement by reducing a toroidal magnetic field ripple. Aiming at cost-effective installation, orbit-following calculations of energetic ions were carried out for a design of the installation of ferritic steel on the JT-60U by using the fully three dimensional magnetic field orbit-following Monte-Carlo (F3D OFMC) code, which had been developed for ferritic insert experiments on the JFT-2M and can treat the complex magnetic field structure produced by ferritic inserts. The installed FSTs add a non-linear magnetic field on magnetic sensors for plasma control and an equilibrium calculation. The code for real-time control has been modified to take into account the magnetic field by the FSTs. The plasma operation was successfully resumed after usual conditioning processes and real-time plasma control was successfully carried out. The heat load measurement indicates the improved confinement of energetic ions. These results are important for practical application of the ferritic steel, which is a leading candidate of a structural material on a DEMO reactor

Chemical bonding and magnetic properties of gadolinium (Gd) substituted cobalt ferrite

International Nuclear Information System (INIS)

Puli, Venkata Sreenivas; Adireddy, Shiva; Ramana, C.V.

2015-01-01

Graphical abstract: Room temperature Raman spectra of CoFe 2−x Gd x O 4 (CFGO, x = 0.0–0.3) compounds as a function of wavenumber (cm −1 ). - Highlights: • Gd substituted ferrites were synthesized under controlled concentration. • Gd ion induced lattice dynamical changes are significant. • Enhanced magnetization is observed upon Gd-incorporation in cobalt ferrite. • A correlation between lattice dynamics and magnetic properties is established. - Abstract: Polycrystalline gadolinium (Gd) substituted cobalt ferrites (CoFe 2−x Gd x O 4 ; x = 0–0.3, referred to CFGO) ceramics have been synthesized by solid state reaction method. Chemical bonding, crystal structure and magnetic properties of CFGO compounds have been evaluated as a function of Gd-content. X-ray diffraction (XRD) and Raman spectroscopic analyses confirmed the formation of inverse spinel cubic structure. However, a secondary ortho-ferrite phase (GdFeO 3 ) nucleates for higher values of Gd-content. A considerable increase in the saturation magnetization has been observed upon the initial substitution of Gd (x = 0.1). The saturation magnetization drastically decreases at higher Gd content (x ⩾ 0.3). No contribution from ortho-ferrite GdFeO 3 phase is noted to the magnetic properties. The increase in the magnetic saturation magnetization is attributed to the higher magnetic moment of Gd 3+ (4f 7 ) residing in octahedral sites is higher when compared to that of Fe 3+ (3d 5 ) and as well due to the migration of Co 2+ (3d 7 ) ions from the octahedral to the tetrahedral sites with a magnetic moment aligned anti-parallel to those of rare earth (RE 3+ ) ions in the spinel lattice. Increase in coercivity with increase in Gd 3+ is content is attributed to magnetic anisotropy in the ceramics

Permanent magnet based dipole magnets for next generation light sources

Directory of Open Access Journals (Sweden)

Takahiro Watanabe

2017-07-01

Full Text Available We have developed permanent magnet based dipole magnets for the next generation light sources. Permanent magnets are advantageous over electromagnets in that they consume less power, are physically more compact, and there is a less risk of power supply failure. However, experience with electromagnets and permanent magnets in the field of accelerators shows that there are still challenges to replacing main magnets of accelerators for light sources with permanent magnets. These include the adjustability of the magnetic field, the temperature dependence of permanent magnets, and the issue of demagnetization. In this paper, we present a design for magnets for future light sources, supported by experimental and numerical results.

Tuning the magnetism of ferrite nanoparticles

Energy Technology Data Exchange (ETDEWEB)

Viñas, S. Liébana [Faculty of Physics and CENIDE, University Duisburg-Essen, Duisburg 47048 (Germany); Departamento de Física Aplicada, Universidade de Vigo, Vigo 36310 (Spain); Simeonidis, K. [Department of Physics, Aristotle University of Thessaloniki, Thessaloniki 54124 (Greece); Li, Z.-A.; Ma, Z. [Faculty of Physics and CENIDE, University Duisburg-Essen, Duisburg 47048 (Germany); Myrovali, E.; Makridis, A.; Sakellari, D. [Department of Physics, Aristotle University of Thessaloniki, Thessaloniki 54124 (Greece); Angelakeris, M., E-mail: agelaker@auth.gr [Department of Physics, Aristotle University of Thessaloniki, Thessaloniki 54124 (Greece); Wiedwald, U.; Spasova, M. [Faculty of Physics and CENIDE, University Duisburg-Essen, Duisburg 47048 (Germany); Farle, M., E-mail: michael.farle@uni-due.de [Faculty of Physics and CENIDE, University Duisburg-Essen, Duisburg 47048 (Germany)

2016-10-01

The importance of magnetic interactions within an individual nanoparticle or between adjacent ones is crucial not only for the macroscopic collective magnetic behavior but for the AC magnetic heating efficiency as well. On this concept, single-(MFe{sub 2}O{sub 4} where M=Fe, Co, Mn) and core–shell ferrite nanoparticles consisting of a magnetically softer (MnFe{sub 2}O{sub 4}) or magnetically harder (CoFe{sub 2}O{sub 4}) core and a magnetite (Fe{sub 3}O{sub 4}) shell with an overall size in the 10 nm range were synthesized and studied for their magnetic particle hyperthermia efficiency. Magnetic measurements indicate that the coating of the hard magnetic phase (CoFe{sub 2}O{sub 4}) by Fe{sub 3}O{sub 4} provides a significant enhancement of hysteresis losses over the corresponding single-phase counterpart response, and thus results in a multiplication of the magnetic hyperthermia efficiency opening a novel pathway for high-performance, magnetic hyperthermia agents. At the same time, the existence of a biocompatible Fe{sub 3}O{sub 4} outer shell, toxicologically renders these systems similar to iron-oxide ones with significantly milder side-effects. - Highlights: • Magnetic hyperthermia is studied for 10 nm single and core/shell ferrite nanoparticles. • Maximum heating rate is observed for Fe{sub 3}O{sub 4}-coated CoFe{sub 2}O{sub 4} nanoparticles. • The increase is attributed to the interaction of phases with different anisotropy. • The presence of biocompatible Fe{sub 3}O{sub 4} shell potentially minimizes toxic side-effects.

Development of Ferrite-Coated Soft Magnetic Composites: Correlation of Microstructure to Magnetic Properties

Science.gov (United States)

Sunday, Katie Jo

Soft magnetic composites (SMCs) comprised of ferrite-coated ferrous powder permit isotropic magnetic flux capabilities, lower core losses, and complex designs through the use of traditional powder metallurgy techniques. Current coating materials and methods are vastly limited by the nonmagnetic properties of organic and some inorganic coatings and their inability to withstand high heat treatments for proper stress relief of core powder after compaction. Ferrite-based coatings are ferrimagnetic, highly resistive, and boast high melting temperatures, thus providing adequate electrical barriers between metallic particles. These insulating layers are necessary for reducing eddy current losses by increasing resistivity in order to improve the overall magnetic efficiency and subsequent frequency range. The goals of this work are to correlate ferrite-coated Fe powder composites microstructure for the coating and core powder to magnetic properties such as permeability, coercivity, and core loss. We first explore the relevant concepts of SMC materials from their composition to processing steps to pertinent properties. This thesis employs a suite of characterization techniques for powder and composite properties. We use X-ray diffraction, scanning electron microscopy, and transmission electron microscopy to provide a complete understanding of the effect of processing conditions on ferrite-coated Fe-based SMCs. Magnetic, mechanical, and electrical properties are then analyzed to correlate microstructural features and determine their effect on such properties. In the second part of this thesis, we present a proof of concept study on Al2O3- and Al2O3- Fe3O4-coated Fe powder composites, illustrating magnetization is highly dependent on ferromagnetic volume. We then expand on previous work to compare an ideal, crystalline state using Fe3O 4-Fe thin film heterostructures to a highly strained state using bulk powder studies. Fe3O4-coated Fe composites are produced via mechanical

21 CFR 886.4445 - Permanent magnet.

Science.gov (United States)

2010-04-01

... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Permanent magnet. 886.4445 Section 886.4445 Food... DEVICES OPHTHALMIC DEVICES Surgical Devices § 886.4445 Permanent magnet. (a) Identification. A permanent magnet is a nonelectric device that generates a magnetic field intended to find and remove metallic...

Magnetic properties of bioactive glass-ceramics containing nanocrystalline zinc ferrite

International Nuclear Information System (INIS)

Singh, Rajendra Kumar; Srinivasan, A.

2011-01-01

Glass-ceramics with finely dispersed zinc ferrite (ZnFe 2 O 4 ) nanocrystallites were obtained by heat treatment of x(ZnO,Fe 2 O 3 )(65-x)SiO 2 20(CaO,P 2 O 5 )15Na 2 O (6≤x≤21 mole%) glasses. X-ray diffraction patterns of the glass-ceramic samples revealed the presence of calcium sodium phosphate [NaCaPO 4 ] and zinc ferrite [ZnFe 2 O 4 ] as major crystalline phases. Zinc ferrite present in nanocrystalline form contributes to the magnetic properties of the glass-ceramic samples. Magnetic hysteresis cycles of the glass-ceramic samples were obtained with applied magnetic field sweeps of ±20 kOe and ±500 Oe, in order to evaluate the potential of these glass-ceramics for hyperthermia treatment of cancer. The evolution of magnetic properties in these samples, viz., from a partially paramagnetic to fully ferrimagnetic nature has been explored using magnetometry and X-ray diffraction studies. - Research highlights: → The glass-ceramics contain bone mineral and magnetic phases. → Calcium sodium phosphate and zinc ferrite nanocrystallites have been identified in all the sample. → With an increase in ZnO and Fe2O3 content, magnetic property of samples evolved from partially paramagnetic to fully ferrimagnetic nature. → Large magnetic hysteresis loops have been obtained for samples with high ZnO+Fe2O3 content.

Influence of the magnetic dead layer thickness of Mg-Zn ferrites nanoparticle on their magnetic properties

Energy Technology Data Exchange (ETDEWEB)

El-Sayed, H.M. [Physics Department, Faculty of Science, Ain Shams University, Cairo (Egypt); Ali, I.A.; Azzam, A. [Nuclear Physics Department, Nuclear Research Center, Atomic Energy Authority (Egypt); Sattar, A.A. [Physics Department, Faculty of Science, Ain Shams University, Cairo (Egypt)

2017-02-15

Nanoparticle ferrite with chemical formula Mg{sub (1−x)}Zn{sub x}Fe{sub 2}O{sub 4} (where x=0.0, 0.2, 0.4, 0.6, 0.8 and 1) were prepared by sol-gel technique. Single phase structure of these ferrites was confirmed using X-ray diffraction (XRD). Transmission Electron Microscope (TEM) showed that the particle size of the samples in the range of (5.7–10.6 nm). The hysteresis studies showed superparamagnetic behaviour at room temperature. The magnetization behaviour with Zn-content is expressed in the light of Yafet-Kittel angles. The dead layer thickness (t) was calculated and its effect on the magnetization and magnetic losses was debated. The Specific Absorption Rate (SAR) in an alternating magnetic field with frequency 198 kHz for these ferrites has been studied. It is found that, the thickness of magnetic dead layer of the surface of the materials has greatly affected the SAR value of the samples. - Highlights: • Synthesis of Mg-Zn nanoparticle ferrite by sol-gel technique. • Methods of dead layer thickness calculation. • Magnetic behaviour explanation. • Relation between the Specific Absorption Rate, dead layer thickness and particle size.

Microwave processed NiMg ferrite: Studies on structural and magnetic properties

International Nuclear Information System (INIS)

Chandra Babu Naidu, K.; Madhuri, W.

2016-01-01

Ferrites are magnetic semiconductors realizing an important role in electrical and electronic circuits where electrical and magnetic property coupling is required. Though ferrite materials are known for a long time, there is a large scope in the improvement of their properties (vice sintering and frequency dependence of electrical and magnetic properties) with the current technological trends. Forth coming technology is aimed at miniaturization and smart gadgets, electrical components like inductors and transformers cannot be included in integrated circuits. These components are incorporated into the circuit as surface mount devices whose fabrication involves low temperature co-firing of ceramics and microwave monolithic integrated circuits technologies. These technologies demand low temperature sinter-ability of ferrites. This article presents low temperature microwave sintered Ni–Mg ferrites of general chemical formula Ni_1_−_xMg_xFe_2O_4 (x=0, 0.2, 0.4, 0.5, 0.6, 0.8, 1) for potential applications as transformer core materials. The series of ferrites are characterized using X-ray diffractometer, scanning electron microscopy, Fourier transform infrared and vibrating sample magnetometer for investigating structural, morphological and magnetic properties respectively. The initial permeability is studied with magnesium content, temperature and frequency in the temperature range of 308 K–873 K and 42 Hz–5 MHz. - Highlights: • First article on microwave processed NiMgFe_2O_4 giving. • The article gives systematic magnetic studies. • Cation distribution is discussed based on magnetic moments from VSM. • Promising candidates for transformer core and soft magnet manufacturing.

Microwave processed NiMg ferrite: Studies on structural and magnetic properties

Energy Technology Data Exchange (ETDEWEB)

Chandra Babu Naidu, K.; Madhuri, W., E-mail: madhuriw12@gmail.com

2016-12-15

Ferrites are magnetic semiconductors realizing an important role in electrical and electronic circuits where electrical and magnetic property coupling is required. Though ferrite materials are known for a long time, there is a large scope in the improvement of their properties (vice sintering and frequency dependence of electrical and magnetic properties) with the current technological trends. Forth coming technology is aimed at miniaturization and smart gadgets, electrical components like inductors and transformers cannot be included in integrated circuits. These components are incorporated into the circuit as surface mount devices whose fabrication involves low temperature co-firing of ceramics and microwave monolithic integrated circuits technologies. These technologies demand low temperature sinter-ability of ferrites. This article presents low temperature microwave sintered Ni–Mg ferrites of general chemical formula Ni{sub 1−x}Mg{sub x}Fe{sub 2}O{sub 4} (x=0, 0.2, 0.4, 0.5, 0.6, 0.8, 1) for potential applications as transformer core materials. The series of ferrites are characterized using X-ray diffractometer, scanning electron microscopy, Fourier transform infrared and vibrating sample magnetometer for investigating structural, morphological and magnetic properties respectively. The initial permeability is studied with magnesium content, temperature and frequency in the temperature range of 308 K–873 K and 42 Hz–5 MHz. - Highlights: • First article on microwave processed NiMgFe{sub 2}O{sub 4} giving. • The article gives systematic magnetic studies. • Cation distribution is discussed based on magnetic moments from VSM. • Promising candidates for transformer core and soft magnet manufacturing.

Self-biased cobalt ferrite nanocomposites for microwave applications

International Nuclear Information System (INIS)

Hannour, Abdelkrim; Vincent, Didier; Kahlouche, Faouzi; Tchangoulian, Ardaches; Neveu, Sophie; Dupuis, Vincent

2014-01-01

Oriented CoFe 2 O 4 nanoparticles, dispersed in polymethyl methacrylate (PMMA) matrix, were fabricated by magnetophoretic deposition of functionalized nanocolloidal cobalt ferrite particles into porous alumina membrane. Their magnetic behavior exhibits an out-of-plane easy axis with a large remanent magnetization and coercitivity. This orientation allows high effective internal magnetic anisotropy that contributes to the permanent bias along the wire axis. The microwave studies reveal a ferromagnetic resonance at 46.5 and 49.5 GHz, depending on the filling ratio of the membrane. Ansoft High Frequency Structure Simulator (Ansoft HFSS) simulations are in good agreement with experimental results. Such nanocomposite is presented as one of the promising candidates for microwave devices (circulators, isolators, noise suppressors etc.). - Highlights: • Oriented magnetic CoFe 2 O 4 nanoparticles were fabricated by magnetophoretic deposition of functionalized cobalt ferrite particles into porous alumina membrane. • The nanocomposite obtained presents an out-of-plane easy axis with a large remanent magnetization and coercitivity. • The high effective internal magnetic anisotropy contributes to the permanent bias along the wire axis. • The frequency ferromagnetic resonance ranges from 46.5 to 49.5 GHz, depending on the filling ratio of the membrane. • We have obtained a good agreement between Ansoft High Frequency Structure Simulator simulations and experimental results

Comparing superconducting and permanent magnets for magnetic refrigeration

DEFF Research Database (Denmark)

Bjørk, Rasmus; Nielsen, Kaspar Kirstein; Bahl, C. R. H.

2016-01-01

We compare the cost of a high temperature superconducting (SC) tape-based solenoidwith a permanent magnet (PM) Halbach cylinder for magnetic refrigeration.Assuming a five liter active magnetic regenerator volume, the price of each type ofmagnet is determined as a function of aspect ratio...... of the regenerator and desiredinternal magnetic field. It is shown that to produce a 1 T internal field in theregenerator a permanent magnet of hundreds of kilograms is needed or an area ofsuperconducting tape of tens of square meters. The cost of cooling the SC solenoidis shown to be a small fraction of the cost...... of the SC tape. Assuming a cost ofthe SC tape of 6000 $/m2 and a price of the permanent magnet of 100 $/kg, thesuperconducting solenoid is shown to be a factor of 0.3-3 times more expensive thanthe permanent magnet, for a desired field from 0.5-1.75 T and the geometrical aspectratio of the regenerator...

Modern permanent magnetic materials - preparation and properties

International Nuclear Information System (INIS)

Rodewald, W.

1989-01-01

First of all, the basic properties of the classical (steel, AlNiCo) permanent magnetic materials and the modern rare-earth (RE) permanent magnetic materials are compared. Since the properties of RE permanent magnets depend on the particular production process, the fundamentals of the main industrial processes (powder metallurgy, rapid-solidification technique) are described and the typical properties are explained. Furthermore the production processes in development such as mechanical alloying, melt spinning technique and extrusion upsetting are briefly outlined. For applying the permanent magnets, they have to be completely magnetized. The magnetization behaviour of the various RE permanent magnets is discussed by means of the internal demagnetization curve. Finally the various influences on the temperature stability of RE permanent magnets are compiled. (orig./MM) [de

Topology optimized permanent magnet systems

DEFF Research Database (Denmark)

Bjørk, Rasmus; Bahl, Christian; Insinga, Andrea Roberto

2017-01-01

Topology optimization of permanent magnet systems consisting of permanent magnets, high permeability iron and air is presented. An implementation of topology optimization for magnetostatics is discussed and three examples are considered. The Halbach cylinder is topology optimized with iron...... and an increase of 15% in magnetic efficiency is shown. A topology optimized structure to concentrate a homogeneous field is shown to increase the magnitude of the field by 111%. Finally, a permanent magnet with alternating high and low field regions is topology optimized and a ΛcoolΛcool figure of merit of 0...

Cooling of the LHC Injection Kicker Magnet Ferrite Yoke: Measurements and Future Proposals

CERN Document Server

Sobiech, Z; Bouleghlimat, S; Ducimetière, L; Garlaschè, M; Kramer, T; Namora, V; Noulibos, R; Sillanoli, Y; Weterings, W

2014-01-01

LHC operation with high intensity beam, stable for many hours, resulted in significant heating of the ferrite yoke of the LHC Injection Kicker Magnets. For one kicker magnet the ferrite yoke approached its Curie temperature. As a result of a long thermal time-constant the yoke can require several hours to cool sufficiently to allow re-injection of beam, thus limiting the running efficiency of the LHC. The beam screen, which screens the ferrite yoke from wakefields, has been upgraded to limit ferrite heating. In addition it is important to improve the cooling of the ferrite yoke: one method is to increase the internal emissivity of the cylindrical vacuum tank, in which the kicker magnet is installed. This paper describes a method developed for measuring the emissivity of the inside of the tanks, which has been benchmarked against measurements of the ferrite yoke temperature during heat treatment in an oven and transient thermal simulations. Conclusions are drawn regarding an ion bombardment technique evaluated...

Phase controlled synthesis of (Mg, Ca, Ba)-ferrite magnetic nanoparticles with high uniformity

International Nuclear Information System (INIS)

Wang, S.F.; Li, Q.; Zu, X.T.; Xiang, X.; Liu, W.; Li, S.

2016-01-01

(Mg, Ca, Ba)-ferrite magnetic nanoparticles were successfully synthesized through modifying the atomic ratio of polysaccharide and chelating agent at an optimal sintering temperature. In the process, the polysaccharide plays an important role in drastically shrinking the precursor during the gel drying process. In the metal-complex structure, M"2"+ ion active sites were coordinated by −OH of the water molecules except for EDTA anions. The MFe_2O_4 magnetic nanoparticles exhibited enhanced magnetic properties when compared with nano-MFe_2O_4 of similar particle size synthesized by other synthesis route reported in the literature. In particular, the sintering temperature improves the crystallinity and increases the hysteresis loop squareness ratio of (Mg, Ca, Ba)-ferrite nanoparticles significantly. - Graphical abstract: Schematic representation of the proposed model for MFe_2O_4 nanoparticle synthesis, starting from EDTA-chelated M"2"+ (M=Mg, Ca, or Ba) cations (left). High dispersion (Mg, Ca, Ba)-ferrite magnetic nanoparticles were prepared by a modified polyacrylamide gel route. Optimized utilization of polysaccharide, chelating agent, and sintering temperature allowed the formation of (Mg, Ca, Ba)-ferrite nanoparticles with a narrow diameter distribution. - Highlights: • We report a modified polyacrylamide gel route to synthesize (Mg, Ca, Ba)-ferrite magnetic nanoparticles. • Chelate mechanism of metal ions (Mg, Ca, Ba) and EDTA has been discussed. • Phase transformation process of (Mg, Ca, Ba)-ferrites has been discussed. • The preparation method increases the hysteresis loop squareness ratio of (Mg, Ca, Ba)-ferrite nanoparticles.

Chemical bonding and magnetic properties of gadolinium (Gd) substituted cobalt ferrite

Energy Technology Data Exchange (ETDEWEB)

Puli, Venkata Sreenivas, E-mail: vspuli@utep.edu [Department of Mechanical Engineering, University of Texas, El Paso, TX 79968 (United States); Adireddy, Shiva [Department of Physics and Engineering Physics, Tulane University, New Orleans, LA 70118 (United States); Ramana, C.V. [Department of Mechanical Engineering, University of Texas, El Paso, TX 79968 (United States)

2015-09-25

Graphical abstract: Room temperature Raman spectra of CoFe{sub 2−x}Gd{sub x}O{sub 4} (CFGO, x = 0.0–0.3) compounds as a function of wavenumber (cm{sup −1}). - Highlights: • Gd substituted ferrites were synthesized under controlled concentration. • Gd ion induced lattice dynamical changes are significant. • Enhanced magnetization is observed upon Gd-incorporation in cobalt ferrite. • A correlation between lattice dynamics and magnetic properties is established. - Abstract: Polycrystalline gadolinium (Gd) substituted cobalt ferrites (CoFe{sub 2−x}Gd{sub x}O{sub 4}; x = 0–0.3, referred to CFGO) ceramics have been synthesized by solid state reaction method. Chemical bonding, crystal structure and magnetic properties of CFGO compounds have been evaluated as a function of Gd-content. X-ray diffraction (XRD) and Raman spectroscopic analyses confirmed the formation of inverse spinel cubic structure. However, a secondary ortho-ferrite phase (GdFeO{sub 3}) nucleates for higher values of Gd-content. A considerable increase in the saturation magnetization has been observed upon the initial substitution of Gd (x = 0.1). The saturation magnetization drastically decreases at higher Gd content (x ⩾ 0.3). No contribution from ortho-ferrite GdFeO{sub 3} phase is noted to the magnetic properties. The increase in the magnetic saturation magnetization is attributed to the higher magnetic moment of Gd{sup 3+} (4f{sup 7}) residing in octahedral sites is higher when compared to that of Fe{sup 3+} (3d{sup 5}) and as well due to the migration of Co{sup 2+} (3d{sup 7}) ions from the octahedral to the tetrahedral sites with a magnetic moment aligned anti-parallel to those of rare earth (RE{sup 3+}) ions in the spinel lattice. Increase in coercivity with increase in Gd{sup 3+} is content is attributed to magnetic anisotropy in the ceramics.

Magnetic Properties of Ni-Zn Ferrite Prepared with the Layered Precursor Method

International Nuclear Information System (INIS)

Zhou Xin; Hou Zhi-Ling; Li Feng; Qi Xin

2010-01-01

We prepare NiZnFe 2 O 4 soft magnetic ferrites with different molar ratios with the layered precursor method and investigate their magnetic properties. In the layered precursor, metal ions are scattered on the layer plate in a certain way on account of the effect of lowest lattice energy and lattice orientation. After high temperature calcinations, spinel ferrites with uniform structural component and single magnetic domain can be obtained, and the magnetic property is improved greatly. NiZnFe 2 O 4 ferrites prepared have the best specific saturation magnetization of 79.15 emu·g −1 , higher than that of 68 emu·g −1 prepared by the chemical co-precipitation method and that of 59 emu·g −1 prepared by the emulsion-gel method. Meanwhile the coercivity of NiZnFe 2 O 4 ferrites prepared by layered precursor method is 14 kA·m −1 , lower than that of 50 emu·g −1 prepared by the co-precipitation method and that of 59 emu·g −1 prepared by the emulsion-gel method. (condensed matter: electronic structure, electrical, magnetic, and optical properties)

New developments in NdFeB-based permanent magnets

International Nuclear Information System (INIS)

Liu, Z.W.

2011-01-01

NdFeB based alloys have been used as permanent magnets for almost thirty years. The recent researches aim at optimizing the composition, microstructure and properties, reducing cost, and developing new processes. The demand for sintered magnet is increasing. Efforts are directed towards improving properties by controlling grain boundary diffusion, minimizing the rare earth (RE) content and also improving production yield. As for bonded magnets, to enhance remanence and energy product, nanocrystalline powders are employed. High thermal stability has been realized by mixing NdFeB with hard ferrite powders. For nanocrystalline and nano composite NdFeB based alloys, both compositional modification and microstructural optimization have been carried out. New approaches have also been proposed to prepare NdFeB magnets with idea structure. Surfactant assisted ball milling is a good top-down method to obtain nano sized hard magnetic particles and anisotropic nano flakes. Synthesis of NdFeB nanoparticles and NdFeB/Fe (Co) nano composite powders by bottom-up techniques, such as chemical reduction process and co-precipitation, has been successful very recently. To assemble nanocrystalline NdFeB powders or nanoparticles into bulk magnets, various novel consolidation processes including spark plasma sintering and high velocity press have been employed. Hot deformation can be selected as the process to achieve anisotropy in nanocrystalline magnets. (author)

Macroscopic simulation of isotropic permanent magnets

International Nuclear Information System (INIS)

Bruckner, Florian; Abert, Claas; Vogler, Christoph; Heinrichs, Frank; Satz, Armin; Ausserlechner, Udo; Binder, Gernot; Koeck, Helmut; Suess, Dieter

2016-01-01

Accurate simulations of isotropic permanent magnets require to take the magnetization process into account and consider the anisotropic, nonlinear, and hysteretic material behaviour near the saturation configuration. An efficient method for the solution of the magnetostatic Maxwell equations including the description of isotropic permanent magnets is presented. The algorithm can easily be implemented on top of existing finite element methods and does not require a full characterization of the hysteresis of the magnetic material. Strayfield measurements of an isotropic permanent magnet and simulation results are in good agreement and highlight the importance of a proper description of the isotropic material. - Highlights: • Simulations of isotropic permanent magnets. • Accurate calculation of remanence magnetization and strayfield. • Comparison with strayfield measurements and anisotropic magnet simulations. • Efficient 3D FEM–BEM coupling for solution of Maxwell equations.

Superconducting permanent magnets and their application in magnetic levitation

International Nuclear Information System (INIS)

Schultz, L.; Krabbes, G.; Fuchs, G.; Pfeiffer, W.; Mueller, K.H.

2002-01-01

Superconducting permanent magnets form a completely new class of permanent magnets. Of course, they must be cooled to 77 K or below. At very low temperatures (24 K) their magnetization can be a factor of 10 higher than that of the best conventional magnets, providing magnetic forces and energies which are up to two orders of magnitude higher. These new supermagnets became only recently available by the extreme improvement of the quality of melt-textured massive YBa 2 Cu 3 O x samples. Besides having a high magnetization, these superconducting permanent magnets can freeze in any given magnetic field configuration allowing completely new applications like superconducting transport systems or superconducting magnetic bearings. (orig.)

Magnetization reversal processes in bonded magnets made from a mixture of Nd-(Fe,Co)-B and strontium ferrite powders

Science.gov (United States)

Dospial, M.; Plusa, D.

2013-03-01

Isotropic epoxy-resin bonded magnets composed of different amounts of Magnequench MQP-B and strontium ferrite powders have been prepared using a compression molding technique. The magnetic parameters for magnets with different amounts of strontium ferrite and magnetization reversal processes have been studied by the measurement of the initial magnetization curves, the major hysteresis loops measured at a field up to 14 T and sets of recoil loops. The enhancement of μ0MR and μ0HC is observed in comparison with the calculated values. From the recoil loops the field dependences of the reversible, irreversible and total magnetization components and the differential susceptibilities were derived. From the dependence of the irreversible magnetization component versus an applied field it was deduced that the main mechanism of magnetization reversal process is the pinning of domain walls in MQP-B and strontium ferrite grains. The interactions between the magnetic particles and grains have been examined by the analysis of the δM plot. The δM behavior of magnets with ferrite has been interpreted as being composed of magnetizing exchange coupling and demagnetizing dipolar interactions.

Periodic permanent magnet focused klystron

Science.gov (United States)

Ferguson, Patrick; Read, Michael; Ives, R Lawrence

2015-04-21

A periodic permanent magnet (PPM) klystron has beam transport structures and RF cavity structures, each of which has permanent magnets placed substantially equidistant from a beam tunnel formed about the central axis, and which are also outside the extent of a cooling chamber. The RF cavity sections also have permanent magnets which are placed substantially equidistant from the beam tunnel, but which include an RF cavity coupling to the beam tunnel for enhancement of RF carried by an electron beam in the beam tunnel.

Comparing superconducting and permanent magnets for magnetic refrigeration

Directory of Open Access Journals (Sweden)

R. Bjørk

2016-05-01

Full Text Available We compare the cost of a high temperature superconducting (SC tape-based solenoid with a permanent magnet (PM Halbach cylinder for magnetic refrigeration. Assuming a five liter active magnetic regenerator volume, the price of each type of magnet is determined as a function of aspect ratio of the regenerator and desired internal magnetic field. It is shown that to produce a 1 T internal field in the regenerator a permanent magnet of hundreds of kilograms is needed or an area of superconducting tape of tens of square meters. The cost of cooling the SC solenoid is shown to be a small fraction of the cost of the SC tape. Assuming a cost of the SC tape of 6000 $/m2 and a price of the permanent magnet of 100 $/kg, the superconducting solenoid is shown to be a factor of 0.3-3 times more expensive than the permanent magnet, for a desired field from 0.5-1.75 T and the geometrical aspect ratio of the regenerator. This factor decreases for increasing field strength, indicating that the superconducting solenoid could be suitable for high field, large cooling power applications.

Topology optimized permanent magnet systems

Science.gov (United States)

Bjørk, R.; Bahl, C. R. H.; Insinga, A. R.

2017-09-01

Topology optimization of permanent magnet systems consisting of permanent magnets, high permeability iron and air is presented. An implementation of topology optimization for magnetostatics is discussed and three examples are considered. The Halbach cylinder is topology optimized with iron and an increase of 15% in magnetic efficiency is shown. A topology optimized structure to concentrate a homogeneous field is shown to increase the magnitude of the field by 111%. Finally, a permanent magnet with alternating high and low field regions is topology optimized and a Λcool figure of merit of 0.472 is reached, which is an increase of 100% compared to a previous optimized design.

Phase controlled synthesis of (Mg, Ca, Ba)-ferrite magnetic nanoparticles with high uniformity

Energy Technology Data Exchange (ETDEWEB)

Wang, S.F., E-mail: wangshifa2006@yeah.net [School of Physical Electronics, University of Electronic Science and Technology of China, Chengdu 610054, Sichuan (China); Science and technology on vacuum technology and physics laboratory, Lanzhou Institute of Physics, Lanzhou 730000, Gansu (China); Li, Q. [School of Physical Electronics, University of Electronic Science and Technology of China, Chengdu 610054, Sichuan (China); Zu, X.T., E-mail: xtzu@uestc.edu.cn [Institute of Fundamental and Frontier Sciences, University of Electronic Science and Technology of China, Chengdu 610054, Sichuan (China); Xiang, X.; Liu, W. [School of Physical Electronics, University of Electronic Science and Technology of China, Chengdu 610054, Sichuan (China); Li, S., E-mail: sean.li@unsw.edu.au [School of Material Science and Engineering, University of New South Wales, Sydney 2052 (Australia)

2016-12-01

(Mg, Ca, Ba)-ferrite magnetic nanoparticles were successfully synthesized through modifying the atomic ratio of polysaccharide and chelating agent at an optimal sintering temperature. In the process, the polysaccharide plays an important role in drastically shrinking the precursor during the gel drying process. In the metal-complex structure, M{sup 2+} ion active sites were coordinated by −OH of the water molecules except for EDTA anions. The MFe{sub 2}O{sub 4} magnetic nanoparticles exhibited enhanced magnetic properties when compared with nano-MFe{sub 2}O{sub 4} of similar particle size synthesized by other synthesis route reported in the literature. In particular, the sintering temperature improves the crystallinity and increases the hysteresis loop squareness ratio of (Mg, Ca, Ba)-ferrite nanoparticles significantly. - Graphical abstract: Schematic representation of the proposed model for MFe{sub 2}O{sub 4} nanoparticle synthesis, starting from EDTA-chelated M{sup 2+} (M=Mg, Ca, or Ba) cations (left). High dispersion (Mg, Ca, Ba)-ferrite magnetic nanoparticles were prepared by a modified polyacrylamide gel route. Optimized utilization of polysaccharide, chelating agent, and sintering temperature allowed the formation of (Mg, Ca, Ba)-ferrite nanoparticles with a narrow diameter distribution. - Highlights: • We report a modified polyacrylamide gel route to synthesize (Mg, Ca, Ba)-ferrite magnetic nanoparticles. • Chelate mechanism of metal ions (Mg, Ca, Ba) and EDTA has been discussed. • Phase transformation process of (Mg, Ca, Ba)-ferrites has been discussed. • The preparation method increases the hysteresis loop squareness ratio of (Mg, Ca, Ba)-ferrite nanoparticles.

Self-biased cobalt ferrite nanocomposites for microwave applications

Energy Technology Data Exchange (ETDEWEB)

Hannour, Abdelkrim, E-mail: abdelkrim.hannour@hotmail.com [LT2C Laboratory, Jean-Monnet University, 25 rue Dr. Rémy Annino, F-42000, Saint-Etienne (France); Vincent, Didier; Kahlouche, Faouzi; Tchangoulian, Ardaches [LT2C Laboratory, Jean-Monnet University, 25 rue Dr. Rémy Annino, F-42000, Saint-Etienne (France); Neveu, Sophie; Dupuis, Vincent [UPMC Univ Paris 06, UMR 7195, PECSA, F-75005, Paris (France)

2014-03-15

Oriented CoFe{sub 2}O{sub 4} nanoparticles, dispersed in polymethyl methacrylate (PMMA) matrix, were fabricated by magnetophoretic deposition of functionalized nanocolloidal cobalt ferrite particles into porous alumina membrane. Their magnetic behavior exhibits an out-of-plane easy axis with a large remanent magnetization and coercitivity. This orientation allows high effective internal magnetic anisotropy that contributes to the permanent bias along the wire axis. The microwave studies reveal a ferromagnetic resonance at 46.5 and 49.5 GHz, depending on the filling ratio of the membrane. Ansoft High Frequency Structure Simulator (Ansoft HFSS) simulations are in good agreement with experimental results. Such nanocomposite is presented as one of the promising candidates for microwave devices (circulators, isolators, noise suppressors etc.). - Highlights: • Oriented magnetic CoFe{sub 2}O{sub 4} nanoparticles were fabricated by magnetophoretic deposition of functionalized cobalt ferrite particles into porous alumina membrane. • The nanocomposite obtained presents an out-of-plane easy axis with a large remanent magnetization and coercitivity. • The high effective internal magnetic anisotropy contributes to the permanent bias along the wire axis. • The frequency ferromagnetic resonance ranges from 46.5 to 49.5 GHz, depending on the filling ratio of the membrane. • We have obtained a good agreement between Ansoft High Frequency Structure Simulator simulations and experimental results.

Nanocrystalline permanent magnets with enhanced properties

International Nuclear Information System (INIS)

Leonowicz, M.

2002-01-01

Parameters of permanent magnets result from the combination of intrinsic properties such as saturation magnetization, magnetic exchange, and magnetocrystalline energy, as well as microstructural parameters such as phase structure, grain size, and orientation. Reduction of grain size into nanocrystalline regime (∼ 50 nm) leads to the enhanced remanence which derives from ferromagnetic exchange coupling between highly refined grains. In this study the fundamental phenomena, quantities, and structure parameters, which define nanophase permanent magnets are presented and discussed. The theoretical considerations are confronted with experimental data for nanocrystalline Sm-Fe-N type permanent magnets. (author)

Cylindrical Hall Thrusters with Permanent Magnets

International Nuclear Information System (INIS)

Raitses, Yevgeny; Merino, Enrique; Fisch, Nathaniel J.

2010-01-01

The use of permanent magnets instead of electromagnet coils for low power Hall thrusters can offer a significant reduction of both the total electric power consumption and the thruster mass. Two permanent magnet versions of the miniaturized cylindrical Hall thruster (CHT) of different overall dimensions were operated in the power range of 50W-300 W. The discharge and plasma plume measurements revealed that the CHT thrusters with permanent magnets and electromagnet coils operate rather differently. In particular, the angular ion current density distribution from the permanent magnet thrusters has an unusual halo shape, with a majority of high energy ions flowing at large angles with respect to the thruster centerline. Differences in the magnetic field topology outside the thruster channel and in the vicinity of the channel exit are likely responsible for the differences in the plume characteristics measured for the CHTs with electromagnets and permanent magnets. It is shown that the presence of the reversing-direction or cusp-type magnetic field configuration inside the thruster channel without a strong axial magnetic field outside the thruster channel does not lead to the halo plasma plume from the CHT.

Permanent Magnet Eddy Current Loss Analysis of a Novel Motor Integrated Permanent Magnet Gear

DEFF Research Database (Denmark)

Zhang, Yuqiu; Lu, Kaiyuan; Ye, Yunyue

2012-01-01

In this paper, a new motor integrated permanent magnet gear (MIPMG) is discussed. The focus is on eddy current loss analysis associated to permanent magnets (PMs). A convenient model of MIPMG is provided based on 2-D field-motion coupled time-stepping finite element method for transient eddy...... current analysis. The model takes the eddy current effect of PMs into account in determination of the magnetic field in the air-gap and in the magnet regions. The eddy current losses generated in the magnets are properly interpreted. Design improvements for reducing the eddy current losses are suggested...

Development of FEMAG. Calculation code of magnetic field generated by ferritic plates in the tokamak devices

Energy Technology Data Exchange (ETDEWEB)

Urata, Kazuhiro [Japan Atomic Energy Research Inst., Naka, Ibaraki (Japan). Naka Fusion Research Establishment

2003-03-01

In design of the future fusion devises in which low activation ferritic steel is planned to use as the plasma facing material and/or the inserts for ripple reduction, the appreciation of the error field effect against the plasma as well as the optimization of ferritic plate arrangement to reduce the toroidal field ripple require calculation of magnetic field generated by ferritic steel. However iterative calculations concerning the non-linearity in B-H curve of ferritic steel disturbs high-speed calculation required as the design tool. In the strong toroidal magnetic field that is characteristic in the tokamak fusion devices, fully magnetic saturation of ferritic steel occurs. Hence a distribution of magnetic charges as magnetic field source is determined straightforward and any iteration calculation are unnecessary. Additionally objective ferritic steel geometry is limited to the thin plate and ferritic plates are installed along the toroidal magnetic field. Taking these special conditions into account, high-speed calculation code ''FEMAG'' has been developed. In this report, the formalization of 'FEMAG' code, how to use 'FEMAG', and the validity check of 'FEMAG' in comparison with a 3D FEM code, with the measurements of the magnetic field in JFT-2M are described. The presented examples are numerical results of design studies for JT-60 modification. (author)

Permanent multipole magnets with adjustable strength

International Nuclear Information System (INIS)

Halbach, K.

1983-01-01

Preceded by a short discussion of the motives for using permanent magnets in accelerators, a new type of permanent magnet for use in accelerators is presented. The basic design and most important properties of a quadrople will be described that uses both steel and permanent magnet material. The field gradient produced by this magnet can be adjusted without changing any other aspect of the field produced by this quadrupole. The generalization of this concept to produce other multipole fields, or combination of multipole fields, will also be presented

Permanent multipole magnets with adjustable strength

International Nuclear Information System (INIS)

Halbach, K.

1983-03-01

Preceded by a short discussion of the motives for using permanent magnets in accelerators, a new type of permanent magnet for use in accelerators is presented. The basic design and most important properties of a quadrupole will be described that uses both steel and permanent magnet material. The field gradient produced by this magnet can be adjusted without changing any other aspect of the field produced by this quadrupole. The generalization of this concept to produce other multipole fields, or combination of multipole fields, will also be presented

Effect of additives on the orientation of magnetic Sr-ferrite powders in powder injection molded compacts

Energy Technology Data Exchange (ETDEWEB)

Cho, T.S. [Sangju National Unviersity, Sangju (Korea); Jeung, W.Y. [Korea Institute of Science and Technology, Seoul (Korea)

2001-03-01

The effect of additives on the orientation of magnetic Sr-ferrite powders has been studied during powder injection molding under applied magnetic field for fabricating multi=pole anisotropic sintered Sr-ferrite magnets. The orientation of the Sr-ferrite powders depends sensitively on the fluidity of powder-binder mixture, related to the binder additives and the injection molding temperature, and the magnetic field intensity. The orientation of Sr-ferrite powders is good for the compacts with stearic acid added in the binder system of paraffin wax/ carnauba wax/HDPE, but it is poor of the compacts with silane coupling agent added. The orientation of sr-ferrites higher than 80% is achieved at the following useful conditions; apparent viscosity lower than 2500 poise in 1000 sec {sup -1} shear rate and applied magnetic field higher than 4 kOe. (author). 15 refs., 1 tab., 6 figs.

Structural and magnetic study of dysprosium substituted cobalt ferrite nanoparticles

Energy Technology Data Exchange (ETDEWEB)

Kumar, Hemaunt, E-mail: hvatsal@gmail.com [Department of Physics, Govind Ballabh Pant University of Agr. & Technology, Pantnagar, Uttarakhand 263145 (India); Srivastava, R.C. [Department of Physics, Govind Ballabh Pant University of Agr. & Technology, Pantnagar, Uttarakhand 263145 (India); Pal Singh, Jitendra [Advanced Analysis Centre, Korea Institute of Science and Technology, Seoul 02792 (Korea, Republic of); Negi, P. [Department of Physics, Govind Ballabh Pant University of Agr. & Technology, Pantnagar, Uttarakhand 263145 (India); Agrawal, H.M. [Advanced Analysis Centre, Korea Institute of Science and Technology, Seoul 02792 (Korea, Republic of); Das, D. [UGC-DAE CSR Kolkata Centre, Kolkata 700098 (India); Hwa Chae, Keun [Advanced Analysis Centre, Korea Institute of Science and Technology, Seoul 02792 (Korea, Republic of)

2016-03-01

The present work investigates the magnetic behavior of Dy{sup 3+} substituted cobalt ferrite nanoparticles. X-ray diffraction studies reveal presence of cubic spinel phases in these nanoparticles. Raman spectra of these nanoparticles show change in intensity of Raman bands, which reflects cation redistribution in cubic spinel lattice. Saturation magnetization and coercivity decrease with increase of Dy{sup 3+}concentration in these nanoparticles. Room temperature Mössbauer measurements show the cation redistribution in these nanoparticles and corroborates the results obtained from Raman Spectroscopic measurements. Decrease in magnetization of Dy{sup 3+} substituted cobalt ferrite is attributed to the reduction in the magnetic interaction and cation redistribution. - Highlights: • Slight decrease in crystallite size after Dy{sup 3+} doping. • Saturation magnetization and coercivity decrease after Dy{sup 3+} doping. • Mössbauer measurements show the cation redistribution in the samples.

Influence of particle size on the magnetic spectrum of NiCuZn ferrites for electromagnetic shielding applications

Energy Technology Data Exchange (ETDEWEB)

Wu, Xiaohan; Yan, Shuoqing; Liu, Weihu [School of Optical and Electronic Information, Huazhong University of Science and Technology, Wuhan 430074, Hubei (China); Feng, Zekun, E-mail: fengzekun@mail.hust.edu.cn [School of Optical and Electronic Information, Huazhong University of Science and Technology, Wuhan 430074, Hubei (China); Chen, Yajie; Harris, Vincent G. [Center for Microwave Magnetic Materials and Integrated Circuits, and Department of Electrical and Computer Engineering, Northeastern University, Boston, MA 02115 (United States)

2016-03-01

The effect of ferrite particle size on the magnetic spectra (1 MHz to 1 GHz) of NiCuZn polycrystalline ferrites doped with Co{sub 2}O{sub 3} and Bi{sub 2}O{sub 3} were systematically investigated. The experiments indicate that the ferrite particle size tailored by grinding time and corresponding sintering temperatures is crucial to achieving high permeability, high Q-factor and low magnetic loss, at 13.56 MHz for electromagnetic shielding applications especially in the near field communication (NFC) field. It is evident that high-performance NiZnCu ferrite materials are strongly tailored by morphology and microstructure. It is conclusive that fine ferrite particles and relatively low sintering temperatures are favorable to lowering magnetic loss and enhancing permeability. This work has built a foundation for improvement of the ferrite slurry used for fabrication of large area tape-casting ferrite sheets. - Highlights: • Fine particles are favorable to lowering magnetic loss and enhancing permeability.

Micromagnetics of rare-earth efficient permanent magnets

Science.gov (United States)

Fischbacher, Johann; Kovacs, Alexander; Gusenbauer, Markus; Oezelt, Harald; Exl, Lukas; Bance, Simon; Schrefl, Thomas

2018-05-01

The development of permanent magnets containing less or no rare-earth elements is linked to profound knowledge of the coercivity mechanism. Prerequisites for a promising permanent magnet material are a high spontaneous magnetization and a sufficiently high magnetic anisotropy. In addition to the intrinsic magnetic properties the microstructure of the magnet plays a significant role in establishing coercivity. The influence of the microstructure on coercivity, remanence, and energy density product can be understood by using micromagnetic simulations. With advances in computer hardware and numerical methods, hysteresis curves of magnets can be computed quickly so that the simulations can readily provide guidance for the development of permanent magnets. The potential of rare-earth reduced and rare-earth free permanent magnets is investigated using micromagnetic simulations. The results show excellent hard magnetic properties can be achieved in grain boundary engineered NdFeB, rare-earth magnets with a ThMn12 structure, Co-based nano-wires, and L10-FeNi provided that the magnet’s microstructure is optimized.

Magnetic properties of cobalt ferrite-silica nanocomposites prepared by a sol-gel autocombustion technique

DEFF Research Database (Denmark)

Cannas, C.; Musinu, A.; Piccaluga, G.

2006-01-01

The magnetic properties of cobalt ferrite-silica nanocomposites with different concentrations (15, 30, and 50 wt %) and sizes (7, 16, and 28 nm) of ferrite particles have been studied by static magnetization measurements and Mossbauer spectroscopy. The results indicate a superparamagnetic behavio...

Evaluation of magnetic properties of NI-ZN ferrites obtained by different synthesis methods

International Nuclear Information System (INIS)

Simoes, A.N.; Neiva, L.S.; Simoes, V.N.; Gama, L.; Gomes Filho, A.C.; Oliveira, J.B.L.

2012-01-01

Ceramic oxides that exhibit ferromagnetic behavior represent important commercial products for the electronics industry and are commonly known as ferrites. The Ni-Zn ferrites are considered to be one of the most versatile and soft due to its high electrical resistivity and low eddy current losses. Thus, this study aims to evaluate the magnetic properties of Ni-Zn ferrite obtained by the Pechini and combustion reaction. After synthesis the powders were characterized by XRD, SEM, BET and magnetic measurements. The results showed that for both methods of synthesis used was the formation of the spinel phase of Ni-Zn ferrite. The micrographs show that the powders obtained by both methods have regular shapes and spherical. Were determined by BET surface area is 26 m 2 /g by the Pechini and 13 m 2 /g by combustion. And the samples synthesized by Pechini method obtained the best magnetic characteristics (author)

Dovetail spoke internal permanent magnet machine

Science.gov (United States)

Alexander, James Pellegrino [Ballston Lake, NY; EL-Refaie, Ayman Mohamed Fawzi [Niskayuna, NY; Lokhandwalla, Murtuza [Clifton Park, NY; Shah, Manoj Ramprasad [Latham, NY; VanDam, Jeremy Daniel [West Coxsackie, NY

2011-08-23

An internal permanent magnet (IPM) machine is provided. The IPM machine includes a stator assembly and a stator core. The stator core also includes multiple stator teeth. The stator assembly is further configured with stator windings to generate a stator magnetic field when excited with alternating currents and extends along a longitudinal axis with an inner surface defining a cavity. The IPM machine also includes a rotor assembly and a rotor core. The rotor core is disposed inside the cavity and configured to rotate about the longitudinal axis. The rotor assembly further includes a shaft. The shaft further includes multiple protrusions alternately arranged relative to multiple bottom structures provided on the shaft. The rotor assembly also includes multiple stacks of laminations disposed on the protrusions and dovetailed circumferentially around the shaft. The rotor assembly further includes multiple pair of permanent magnets for generating a magnetic field, which magnetic field interacts with the stator magnetic field to produce a torque. The multiple pair of permanent magnets are disposed between the stacks. The rotor assembly also includes multiple middle wedges mounted between each pair of the multiple permanent magnets.

Adjustable permanent magnet assembly for NMR and MRI

Science.gov (United States)

Pines, Alexander; Paulsen, Jeffrey; Bouchard, Louis S; Blumich, Bernhard

2013-10-29

System and methods for designing and using single-sided magnet assemblies for magnetic resonance imaging (MRI) are disclosed. The single-sided magnet assemblies can include an array of permanent magnets disposed at selected positions. At least one of the permanent magnets can be configured to rotate about an axis of rotation in the range of at least +/-10 degrees and can include a magnetization having a vector component perpendicular to the axis of rotation. The single-sided magnet assemblies can further include a magnet frame that is configured to hold the permanent magnets in place while allowing the at least one of the permanent magnets to rotate about the axis of rotation.

Physical and magnetic properties of (Ba/Sr) substituted magnesium nano ferrites

Science.gov (United States)

Ateia, Ebtesam E.; Takla, E.; Mohamed, Amira T.

2017-10-01

In the presented paper, strontium (Sr) and barium (Ba) nano ferrites were synthesized by citrate auto combustion method. The investigated samples are characterized by X-ray diffraction technique (XRD), field emission scanning electron microscopy, high resolution transmission electron microscopy and energy dispersive X-ray spectroscopy. The structural properties of the obtained samples were examined by XRD analysis showing that the synthesized nanoparticles are in cubic spinel structure. The average crystallite sizes are in the range of 22.66 and 21.95 nm for Mg0.7Ba0.3Fe2O4 and Mg0.7 Sr0.3Fe2O4 respectively. The VSM analysis confirms the existence of ferromagnetic nature of Sr2+/Ba2+ substituted magnesium nano particles. Exchange interaction between hard (Sr/Ba) and soft (Mg) magnetic phases improves the structural and magnetic properties of nano ferrite particles. Rigidity modulus, longitudinal and shear wave velocities are predicted theoretically from Raman spectroscopy and structural data of the investigated spinel ferrite. The magnetic and structural properties of magnesium are enhanced by doping with barium and strontium nano particles. The saturation magnetization, remanent magnetization and coercivity reported on vibrating sample magnetometer curve illustrate the promising industrial and magnetic recording applications of the prepared samples.

Manganese substituted cobalt ferrite magnetostrictive materials for magnetic stress sensor applications

OpenAIRE

Paulsen, J. A.; Ring, A. P.; Lo, C. C. H.; Snyder, John Evan; Jiles, David

2005-01-01

Metal bonded cobalt ferrite composites have been shown to be promising candidate materials for use in magnetoelastic stress sensors, due to their large magnetostriction and high sensitivity of magnetization to stress. However previous results have shown that below 60 °C the cobalt ferrite material exhibits substantial magnetomechanical hysteresis. In the current study, measurements indicate that substituting Mn for some of the Fe in the cobalt ferrite can lower the Curie temperature of the ma...

Iron-based soft magnetic composites with Mn-Zn ferrite nanoparticles coating obtained by sol-gel method

Science.gov (United States)

Wu, Shen; Sun, Aizhi; Xu, Wenhuan; Zhang, Qian; Zhai, Fuqiang; Logan, Philip; Volinsky, Alex A.

2012-11-01

This paper focuses on iron-based soft magnetic composites which were synthesized by utilizing Mn-Zn ferrite nanoparticles to coat iron powder. The nanocrystalline iron powders, with an average particle diameter of 20 nm, were obtained via the sol-gel method. Scanning electron microscopy, energy dispersive X-ray spectroscopy and distribution maps show that the iron particle surface is covered with a thin layer of Mn-Zn ferrites. Mn-Zn ferrite uniformly coated the surface of the powder particles, resulting in a reduced imaginary permeability, increased electrical resistivity and a higher operating frequency of the synthesized magnets. Mn-Zn ferrite coated samples have higher permeability and lower magnetic loss when compared with the non-magnetic epoxy resin coated compacts. The real part of permeability increases by 33.5% when compared with the epoxy resin coated samples at 10 kHz. The effects of heat treatment temperature on crystalline phase formation and on the magnetic properties of the Mn-Zn ferrite were investigated via X-ray diffraction and a vibrating sample magnetometer. Ferrites decomposed to FeO and MnO after annealing above 400 °C in nitrogen; thus it is the optimum annealing temperature to attain the desired permeability.

Nonuniform radiation damage in permanent magnet quadrupoles.

Science.gov (United States)

Danly, C R; Merrill, F E; Barlow, D; Mariam, F G

2014-08-01

We present data that indicate nonuniform magnetization loss due to radiation damage in neodymium-iron-boron Halbach-style permanent magnet quadrupoles. The proton radiography (pRad) facility at Los Alamos uses permanent-magnet quadrupoles for magnifying lenses, and a system recently commissioned at GSI-Darmsdadt uses permanent magnets for its primary lenses. Large fluences of spallation neutrons can be produced in close proximity to these magnets when the proton beam is, intentionally or unintentionally, directed into the tungsten beam collimators; imaging experiments at LANL's pRad have shown image degradation with these magnetic lenses at proton beam doses lower than those expected to cause damage through radiation-induced reduction of the quadrupole strength alone. We have observed preferential degradation in portions of the permanent magnet quadrupole where the field intensity is highest, resulting in increased high-order multipole components.

Nonuniform radiation damage in permanent magnet quadrupoles

International Nuclear Information System (INIS)

Danly, C. R.; Merrill, F. E.; Barlow, D.; Mariam, F. G.

2014-01-01

We present data that indicate nonuniform magnetization loss due to radiation damage in neodymium-iron-boron Halbach-style permanent magnet quadrupoles. The proton radiography (pRad) facility at Los Alamos uses permanent-magnet quadrupoles for magnifying lenses, and a system recently commissioned at GSI-Darmsdadt uses permanent magnets for its primary lenses. Large fluences of spallation neutrons can be produced in close proximity to these magnets when the proton beam is, intentionally or unintentionally, directed into the tungsten beam collimators; imaging experiments at LANL’s pRad have shown image degradation with these magnetic lenses at proton beam doses lower than those expected to cause damage through radiation-induced reduction of the quadrupole strength alone. We have observed preferential degradation in portions of the permanent magnet quadrupole where the field intensity is highest, resulting in increased high-order multipole components

Nonuniform radiation damage in permanent magnet quadrupoles

Energy Technology Data Exchange (ETDEWEB)

Danly, C. R.; Merrill, F. E.; Barlow, D.; Mariam, F. G. [Los Alamos National Laboratory, Los Alamos, New Mexico 87544 (United States)

2014-08-15

We present data that indicate nonuniform magnetization loss due to radiation damage in neodymium-iron-boron Halbach-style permanent magnet quadrupoles. The proton radiography (pRad) facility at Los Alamos uses permanent-magnet quadrupoles for magnifying lenses, and a system recently commissioned at GSI-Darmsdadt uses permanent magnets for its primary lenses. Large fluences of spallation neutrons can be produced in close proximity to these magnets when the proton beam is, intentionally or unintentionally, directed into the tungsten beam collimators; imaging experiments at LANL’s pRad have shown image degradation with these magnetic lenses at proton beam doses lower than those expected to cause damage through radiation-induced reduction of the quadrupole strength alone. We have observed preferential degradation in portions of the permanent magnet quadrupole where the field intensity is highest, resulting in increased high-order multipole components.

Tunable biasing magnetic field design of ferrite tuner for ICRF heating system in EAST

Science.gov (United States)

Manman, XU; Yuntao, SONG; Gen, CHEN; Yanping, ZHAO; Yuzhou, MAO; Guang, LIU; Zhen, PENG

2017-11-01

Ion cyclotron range of frequency (ICRF) heating has been used in tokamaks as one of the most successful auxiliary heating tools and has been adopted in the EAST. However, the antenna load will fluctuate with the change of plasma parameters in the ICRF heating process. To ensure the steady operation of the ICRF heating system in the EAST, fast ferrite tuner (FFT) has been carried out to achieve real-time impedance matching. For the requirements of the FFT impedance matching system, the magnet system of the ferrite tuner (FT) was designed by numerical simulations and experimental analysis, where the biasing magnetic circuit and alternating magnetic circuit were the key researched parts of the ferrite magnet. The integral design goal of the FT magnetic circuit is that DC bias magnetic field is 2000 Gs and alternating magnetic field is ±400 Gs. In the FTT, E-type magnetic circuit was adopted. Ferrite material is NdFeB with a thickness of 30 mm by setting the working point of NdFeB, and the ampere turn of excitation coil is 25 through the theoretical calculation and simulation analysis. The coil inductance to generate alternating magnetic field is about 7 mH. Eddy-current effect has been analyzed, while the magnetic field distribution has been measured by a Hall probe in the medium plane of the biasing magnet. Finally, the test results show the good performance of the biasing magnet satisfying the design and operating requirements of the FFT.

Synthesis, electrical and magnetic properties of sodium borosilicate glasses containing Co-ferrites nanoparticles

Energy Technology Data Exchange (ETDEWEB)

Othman, H.A. [Department of Physics, Faculty of Science, Menoufia University, Shibin El-Kom 32511, Menoufia (Egypt); Eltabey, M.M. [Department of Basic Engineering Science, Faculty of Engineering, Menoufia University, Shibin El-Kom, Menoufia (Egypt); Department of Physics, Faculty of Science, Jazan University (Saudi Arabia); Ibrahim, Samia E.; El-Deen, L.M. Sharaf; Elkholy, M.M. [Department of Physics, Faculty of Science, Menoufia University, Shibin El-Kom 32511, Menoufia (Egypt)

2017-02-01

Co-ferrites nanoparticles that have been prepared by the co-precipitation method were added to sodium borosilicate (Na{sub 2}O–B{sub 2}O{sub 3}–SiO{sub 2}) glass matrix by the solid solution method and they were characterized using X-ray diffraction (XRD), transmission electron microscopy (TEM), Fourier transform infrared (FTIR) and magnetization measurements. (XRD) revealed the formation of the Co-ferrite magnetic crystalline phase embedded in an amorphous matrix in all the samples. The investigated samples by (TEM) showed the formation of the cobalt ferrite nanoparticles with a spherical shape and highly monodispersed with an average size about 13 nm. IR data revealed that the BO{sub 3} and BO{sub 4} are the main structural units of these samples network. IR spectra of the investigated samples showed the characteristic vibration bands of Co-ferrite. Composition and frequency dependent dielectric properties of the prepared samples were measured at room temperature in the frequency range 100–100 kHz. The conductivity was found to increase with increasing cobalt ferrite content. The variations of conductivity and dielectric properties with frequency and composition were discussed. Magnetic hysteresis loops were traced at room temperature using VSM and values of saturation magnetization M{sub S} and coercive field H{sub C} were determined. The obtained results revealed that a ferrimagnetic behavior were observed and as Co-ferrite concentration increases the values of M{sub S} and H{sub C} increase from 2.84 to 8.79 (emu/g) and from 88.4 to 736.3 Oe, respectively.

Permanent magnet design for high-speed superconducting bearings

Science.gov (United States)

Hull, John R.; Uherka, Kenneth L.; Abdoud, Robert G.

1996-01-01

A high temperature superconducting bearing including a permanent magnet rotor levitated by a high temperature superconducting structure. The rotor preferably includes one or more concentric permanent magnet rings coupled to permanent magnet ring structures having substantially triangular and quadrangular cross-sections. Both alternating and single direction polarity magnet structures can be used in the bearing.

Magnetic guns with cylindrical permanent magnets

Czech Academy of Sciences Publication Activity Database

Vokoun, David; Beleggia, M.; Heller, Luděk

2012-01-01

Roč. 324, č. 9 (2012), s. 1715-1719 ISSN 0304-8853 R&D Projects: GA ČR(CZ) GAP107/11/0391; GA AV ČR IAA100100920 Institutional research plan: CEZ:AV0Z10100520 Keywords : permanent magnet * cylindrical magnet * Earnshaw's theorem * magnetic gun * magnetostatic interaction Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 1.826, year: 2012 http://www.sciencedirect.com/science/article/pii/S0304885311008997

Static devices with new permanent magnets

International Nuclear Information System (INIS)

Chavanne, J.; Laforest, J.; Pauthenet, R.

1987-01-01

The high remanence and coercivity of the new permanent magnet materials are of special interest in the static applications. High ordering temperature and are uniaxial anisotropy at the origin of their good permanent magnet properties are obtained in rare earth-transition metal compounds. Binary SmCo/sub 5/ and Sm/sub 2/Co/sub 17/ and ternary Nd/sub 2/Fe/sub 14/B compounds are the basis materials of the best permanent magnets. new concepts of calculations of static devices with these magnets can be applied: the magnetization can be considered as ridig, the density of the surface Amperian current is constant, the relative permeability is approximately 1 and the induction calculations are linear. Examples of hexapoles with Sm-Co and NdFeB magnets are described and the performances are compared. The problems of temperature behavior and corrosion resistance are underlined

Temperature change of various ferrite particles with alternating magnetic field for hyperthermic application

International Nuclear Information System (INIS)

Kim, Dong-Hyun; Lee, Se-Ho; Kim, Kyoung-Nam; Kim, Kwang-Mahn; Shim, In-Bo; Lee, Yong-Keun

2005-01-01

Various ferrites (Fe-, Li-, Ni/Zn/Cu-, Co-, Co/Ni, Ba- and Sr-ferrites) were investigated with respect to their application for hyperthermia. Temperature changes under an alternating magnetic field were observed. The area of hysteresis loop was much larger in the Ba- and Sr-ferrites than for that of the Fe-, Ni/Zn/Cu-, Li-, Co- and Co/Ni-ferrites. Co-ferrite exhibited the most applicable temperature change ΔT=19.25K (29.62W/gs), in distilled water when the field was 110A/m

In-situ magnetization of NdFeB magnets for permanent magnet machines

International Nuclear Information System (INIS)

Chang, L.; Eastham, T.R.; Dawson, G.E.

1991-01-01

In-situ magnetizers are needed to facilitate the assembly of permanent magnet machines and to remagnetize the magnets after weakening due to a fault condition. The air-core magnetizer in association with the silicon steel lamination structure of the rotor has advantages over its iron-core counterpart. This novel method has been used to magnetize the NdFeB magnets in a 30-hp permanent magnet synchronous motor. The magnetizing capability for different magnetizer geometries was investigated for the magnetization of NdFeB material. The design, testing, and operation of this magnetizer are reported in this paper

Effect of Jahn-Teller distortion on the short range magnetic order in copper ferrite

Energy Technology Data Exchange (ETDEWEB)

Abdellatif, M.H., E-mail: Mohamed.abdellatif@iit.it [Nanostrctures Department, Istituto Italiano di Tecnologia, via Morego 30, I-16163 Genova (Italy); Innocenti, Claudia [INSTM—Department of Chemistry, University of Florence, via della Lastruccia 3, I-50019 Sesto Fiorentino, FI (Italy); Liakos, Ioannis [Nanostrctures Department, Istituto Italiano di Tecnologia, via Morego 30, I-16163 Genova (Italy); Scarpellini, Alice; Marras, Sergio [Nanochemistry Department, Istituto Italiano di Tecnologia, via Morego 30, I-16163 Genova (Italy); Salerno, Marco [Nanostrctures Department, Istituto Italiano di Tecnologia, via Morego 30, I-16163 Genova (Italy)

2017-02-15

Copper ferrite of spinel crystal structure was synthesized in the form of nano-particles using citrate-gel auto-combustion method. The sample morphology and composition were identified using scanning electron microscopy, X-ray diffraction, and X-ray spectroscopy. The latter technique reveals an inverse spinel structure with Jahn-Teller tetragonal distortion. The static magnetization was measured using vibrating sample magnetometer. Magnetic force microscopy was used in combination with the magnetization data to demonstrate the finite size effect of the magnetic spins and their casting behavior due to the introduction of copper ions in the tetrahedral magnetic sub-lattices, which results in tetragonal distorting the spinel structure of the copper ferrite. The magnetic properties of materials are a result of the collective behavior of the magnetic spins, and magnetic force microscopy can probe the collective behavior of the magnetic spins in copper ferrite, yet providing a sufficient resolution to map the effects below the micrometer size scale, such as the magnetic spin canting. A theoretical study was done to clarify the finite size effect of Jahn-Teller distortion on the magnetic properties of the material. When the particles are in the nano-scale, below the single domain size, their magnetic properties are very sensitive to their size change. - Highlights: • The spin canting due to Jahn-Teller distortion in Copper ferrite can be detected using magnetic force microscope. • The contrast in the magnetic AFM image can be analyzed to give information not only about the surface spins but also about the canting of the core spins inside the aggregated cluster of magnetic nanoparticle.

Permanent magnet design for high-speed superconducting bearings

International Nuclear Information System (INIS)

Hull, J.R.; Uherka, K.L.; Abdoud, R.G.

1996-01-01

A high temperature superconducting bearing including a permanent magnet rotor levitated by a high temperature superconducting structure is disclosed. The rotor preferably includes one or more concentric permanent magnet rings coupled to permanent magnet ring structures having substantially triangular and quadrangular cross-sections. Both alternating and single direction polarity magnet structures can be used in the bearing. 9 figs

The history of permanent magnet materials

International Nuclear Information System (INIS)

Livingston, J.D.

1990-01-01

Permanent-magnet materials play a large and growing, but largely unseen, role in today's technology. Many common devices in the home and elsewhere, including appliances, computers and printers, contain permanent-magnet motors and actuators. The growth of applications for permanent magnets results in large part from the improvements in magnetic properties, which allow the engineer to design smaller, lighter and more efficient devices. The properties of the greatest technological interest are remanence, coercivity and maximum energy product. All are non-equilibrium and high structure-sensitive. Coercivity is particularly sensitive to microstructure, while remanence is sensitive to texture (crystallographic alignment). The energy product depends on both coercivity and remanence. The more than one hundredfold increase in the available energy product in this century, and the corresponding amount of magnet required for a specific application, are shown

Globally Optimal Segmentation of Permanent-Magnet Systems

DEFF Research Database (Denmark)

Insinga, Andrea Roberto; Bjørk, Rasmus; Smith, Anders

2016-01-01

Permanent-magnet systems are widely used for generation of magnetic fields with specific properties. The reciprocity theorem, an energy-equivalence principle in magnetostatics, can be employed to calculate the optimal remanent flux density of the permanent-magnet system, given any objective...... remains unsolved. We show that the problem of optimal segmentation of a two-dimensional permanent-magnet assembly with respect to a linear objective functional can be reduced to the problem of piecewise linear approximation of a plane curve by perimeter maximization. Once the problem has been cast...

Variable Permanent Magnet Quadrupole

International Nuclear Information System (INIS)

Mihara, T.; Iwashita, Y.; Kyoto U.; Kumada, M.; NIRS, Chiba; Spencer, C.M.; SLAC

2007-01-01

A permanent magnet quadrupole (PMQ) is one of the candidates for the final focus lens in a linear collider. An over 120 T/m strong variable permanent magnet quadrupole is achieved by the introduction of saturated iron and a 'double ring structure'. A fabricated PMQ achieved 24 T integrated gradient with 20 mm bore diameter, 100 mm magnet diameter and 20 cm pole length. The strength of the PMQ is adjustable in 1.4 T steps, due to its 'double ring structure': the PMQ is split into two nested rings; the outer ring is sliced along the beam line into four parts and is rotated to change the strength. This paper describes the variable PMQ from fabrication to recent adjustments

Axial magnetic field produced by axially and radially magnetized permanent rings

International Nuclear Information System (INIS)

Peng, Q.L.; McMurry, S.M.; Coey, J.M.D.

2004-01-01

Axial magnetic fields produced by axially and radially magnetized permanent magnet rings were studied. First, the axial magnetic field produced by a current loop is introduced, from which the axial field generated by an infinitely thin solenoid and by an infinitely thin current disk can be derived. Then the axial fields produced by axially and by radially magnetized permanent magnet rings can be obtained. An analytic formula for the axial fields produced by two axially magnetized rings is given. A permanent magnet with a high axial gradient field is fabricated, the measured results agree with the theoretical calculation very well. As an example, the axial periodic field produced by an arrangement of alternating axially and radially magnetized rings has been discussed

Iron-based soft magnetic composites with Mn–Zn ferrite nanoparticles coating obtained by sol–gel method

International Nuclear Information System (INIS)

Wu, Shen; Sun, Aizhi; Xu, Wenhuan; Zhang, Qian; Zhai, Fuqiang; Logan, Philip; Volinsky, Alex A.

2012-01-01

This paper focuses on iron-based soft magnetic composites which were synthesized by utilizing Mn–Zn ferrite nanoparticles to coat iron powder. The nanocrystalline iron powders, with an average particle diameter of 20 nm, were obtained via the sol–gel method. Scanning electron microscopy, energy dispersive X-ray spectroscopy and distribution maps show that the iron particle surface is covered with a thin layer of Mn–Zn ferrites. Mn–Zn ferrite uniformly coated the surface of the powder particles, resulting in a reduced imaginary permeability, increased electrical resistivity and a higher operating frequency of the synthesized magnets. Mn–Zn ferrite coated samples have higher permeability and lower magnetic loss when compared with the non-magnetic epoxy resin coated compacts. The real part of permeability increases by 33.5% when compared with the epoxy resin coated samples at 10 kHz. The effects of heat treatment temperature on crystalline phase formation and on the magnetic properties of the Mn–Zn ferrite were investigated via X-ray diffraction and a vibrating sample magnetometer. Ferrites decomposed to FeO and MnO after annealing above 400 °C in nitrogen; thus it is the optimum annealing temperature to attain the desired permeability. - Highlights: ► Uniformly coated Mn–Zn ferrite powder increased the operating frequency of SMCs. ► Compared with epoxy coated, the permeability of SMCs increased by 33.5% at 10 kHz. ► 400 °C is the optimum annealing temperature to attain the desired permeability.

Magnetically controlled multifrequency invisibility cloak with a single shell of ferrite material

Science.gov (United States)

Wang, Xiaohua; Liu, Youwen

2015-02-01

A magnetically controlled multifrequency invisibility cloak with a single shell of the isotropic and homogeneous ferrite material has been investigated based on the scattering cancellation method from the Mie scattering theory. The analytical and simulated results have demonstrated that such this shell can drastically reduce the total scattering cross-section of this cloaking system at multiple frequencies. These multiple cloaking frequencies of this shell can be externally controlled since the magnetic permeability of ferrites is well tuned by the applied magnetic field. This may provide a potential way to design a tunable multifrequency invisibility cloak with considerable flexibility.

Spinel ferrite nanocrystals embedded inside ZnO: magnetic, electronic andmagneto-transport properties

Energy Technology Data Exchange (ETDEWEB)

Zhou, Shengqiang; Potzger, K.; Xu, Qingyu; Kuepper, K.; Talut, G.; Marko, D.; Mucklich, A.; Helm, M.; Fassbender, J.; Arenholz, E.; Schmidt, H.

2009-08-21

In this paper we show that spinel ferrite nanocrystals (NiFe{sub 2}O{sub 4}, and CoFe{sub 2}O{sub 4}) can be texturally embedded inside a ZnO matrix by ion implantation and post-annealing. The two kinds of ferrites show different magnetic properties, e.g. coercivity and magnetization. Anomalous Hall effect and positive magnetoresistance have been observed. Our study suggests a ferrimagnet/semiconductor hybrid system for potential applications in magneto-electronics. This hybrid system can be tuned by selecting different transition metal ions (from Mn to Zn) to obtain various magnetic and electronic properties.

New magnetic rails with double-layer Halbach structure by employing NdFeB and ferrite magnets for HTS maglev

Science.gov (United States)

Sun, Ruixue; Zheng, Jun; Zheng, Botian; Qian, Nan; Li, Jipeng; Deng, Zigang

2018-01-01

In the high temperature superconducting (HTS) maglev system, the magnetic rail as an essential infrastructure is needed all along the route to carry passengers and goods to the destinations. Thus, large amount of rare earth magnetic materials are required in the magnetic rail construction. In order to decrease the dependence of magnetic rails on rare earth elements, the ferrite magnet is employed to replace part of the NdFeB magnets containing rare earth elements. Consequently, a new type rail with double-layer Halbach structure is presented, which is consisted of NdFeB and ferrite magnets. In this paper, we designed and fabricated the proposed rail, and further measured its magnetic flux density distribution and electromagnetic force interacting with HTS bulks. Experimental results indicate that, this new type rail, in double-layer Halbach structure, can achieve an equivalent distribution of magnetic flux density and levitation performance as the pure NdFeB Halbach rail, while a 10% reduction in NdFeB magnet consumption can be realized at the same time. In addition this work explores another magnetic material selection for HTS maglev applications. The dependence on rare earth element and the cost of magnetic rails can be further reduced, as the coercive force of ferrite magnets improved.

Synthesis of ferrite nanoparticle by milling process for preparation of single domain magnet

International Nuclear Information System (INIS)

Suryadi; Hasbiyallah; Agus S W; Nurul TR; Budhy Kurniawan

2009-01-01

Study of ferrite nanoparticle synthesis for preparation of single domain magnet by milling of scrap magnet material have been done. Sample preparation were done using disk mill continued with high energy milling (HEM). Some powder were taken after 5, 10 dan 20 hours milling using HEM-E3D. The powder were then characterized using X-Ray Fluorescence (XRF), X-Ray Diffractometer (XRD) and Scanning Electron Microscope (SEM). XRF characterization result, confirmed by XRD analysis result, showed that the sample are of Strontium ferrite phase. Microstructure analysis result showed the occurrence of grain refining process of ferrite particle with increasing of milling time. Particle having size of nanometers successfully obtained, although in unhomogeneous distribution. Magnetic properties characterization result showed the increasing of hysteresis curve area of sample for longer milling time and sintering process. (author)

Observation and manipulation of magnetic domains in sol gel derived thin films of spinel ferrites

Science.gov (United States)

Datar, Ashwini A.; Mathe, Vikas L.

2017-12-01

Thin films of spinel ferrites, namely zinc substituted nickel, cobalt ferrite, and manganese substituted cobalt ferrite, were synthesized using sol-gel derived spin-coating techniques. The films were characterized using x-ray diffraction, field emission scanning electron microscopy, Fourier transform infrared spectroscopy and Raman spectroscopy techniques for the analysis of structural, morphological and vibrational band transition properties, which confirm the spinel phase formation of the films. The magnetic force microscopy (MFM) technique was used to observe the magnetic domain structure present in the synthesized films. Further, the films were subjected to an external DC magnetic field of 2 kG to orient the magnetic domains and analyzed using an ex situ MFM technique.

A novel rhombohedron-like nickel ferrite nanostructure: Microwave combustion synthesis, structural characterization and magnetic properties

Directory of Open Access Journals (Sweden)

G. Suresh Kumar

2016-09-01

Full Text Available Research on nickel ferrite nanostructures has drawn a great interest because of its inherent chemical, physical and electronic properties. In this study, we have synthesized rhombohedron – like nickel ferrite nanostructure by a rapid microwave assisted combustion method using ethylenediamminetetraacetic acid as a chelating agent. X-ray diffraction, Fourier transform infrared spectrometer, transmission electron microscope and energy dispersive X-ray microanalyser were used to characterize the prepared sample. The magnetic behaviour was analysed by means of field dependent magnetization measurement which indicates that the prepared sample exhibits a soft ferromagnetic nature with saturation magnetization of 63.034 emu/g. This technique can be a potential method to synthesize novel nickel ferrite nanostructure with improved magnetic properties.

Investigation of Anisotropic Bonded Magnets in Permanent Magnet Machine Applications

Science.gov (United States)

Khazdozian, H. A.; McCall, S. K.; Kramer, M. J.; Paranthaman, M. P.; Nlebedim, I. C.

Rare earth elements (REE) provide the high energy product necessary for permanent magnets, such as sintered Nd2Fe14B, in many applications like wind energy generators. However, REEs are considered critical materials due to risk in their supply. To reduce the use of critical materials in permanent magnet machines, the performance of anisotropic bonded NdFeB magnets, aligned under varying magnetic field strength, was simulated using 3D finite element analysis in a 3MW direct-drive permanent magnet generator (DDPMG), with sintered N42 magnets used as a baseline for comparison. For direct substitution of the anisotropic bonded magnets, approximately 85% of the efficiency of the baseline model was achieved, irrespective of the alignment field. The torque and power generation of the DDPMG was not found to vary significantly with increase in the alignment field. Finally, design changes were studied to allow for the achievement of rated torque and power with the use of anisotropic bonded magnets, demonstrating the potential for reduction of critical materials in permanent magnets for renewable energy applications. This work was supported by the Critical Materials Institute, an Energy Innovation Hub funded by the U.S. Department of Energy, Office of Energy Efficiency and Renewable Energy, Advanced Manufacturing Office.

Microstructural development of cobalt ferrite ceramics and its influence on magnetic properties

Science.gov (United States)

Kim, Gi-Yeop; Jeon, Jae-Ho; Kim, Myong-Ho; Suvorov, Danilo; Choi, Si-Young

2013-11-01

The microstructural evolution and its influence on magnetic properties in cobalt ferrite were investigated. The cobalt ferrite powders were prepared via a solid-state reaction route and then sintered at 1200 °C for 1, 2, and 16 h in air. The microstructures from sintered samples represented a bimodal distribution of grain size, which is associated with abnormal grain growth behavior. And thus, with increasing sintering time, the number and size of abnormal grains accordingly increased but the matrix grains were frozen with stagnant grain growth. In the sample sintered for 16 h, all of the matrix grains were consumed and the abnormal grains consequently impinged on each other. With the appearance of abnormal grains, the magnetic coercivity significantly decreased from 586.3 Oe (1 h sintered sample) to 168.3 Oe (16 h sintered sample). This is due to the magnetization in abnormal grains being easily flipped. In order to achieve high magnetic coercivity of cobalt ferrite, it is thus imperative to fabricate the fine and homogeneous microstructure.

Three-dimensional quadrupole lenses made with permanent magnets

International Nuclear Information System (INIS)

Ivanov, A.S.

1984-01-01

The performance of accelerator systems with quadrupole magnets can be improved by using permanent magnets in quadrupole lenses. This requires better methods for treating the three-dimensional nature of the magnetic fields and the nonlinear characteristics of the magnets. A numerical method is described for simulating three-dimensional magnetic fields and used to analyze quadrupole lenses and doublets with permanent magnets. The results, which are confirmed experimentally, indicate that both the quadrupole magnetic gradient and the effective field length are changed in permanent-magnet quadrupole lenses when the pole lengths and the gap between the lenses are varied while the other characteristics of the magnets remain unchanged

High performance permanent magnet materials

International Nuclear Information System (INIS)

Sankar, S.G.; Herbst, J.F.; Koon, N.C.

1987-01-01

This book contains 25 selections. Some of the titles are: Initial magnetization behavior of rapidly quenched neodymium-iron-boron magnets; Optimization of liquid dynamic compaction for Fe-Nd-B magnet alloys; Misch-metal and/or aluminum substitutions in Nd-Fe-B permanent magnets; and NdFeB magnets with improved temperature characteristics

XXIst Century Ferrites

International Nuclear Information System (INIS)

Mazaleyrat, F; Zehani, K; Pasko, A; Loyau, V; LoBue, M

2012-01-01

Ferrites have always been a subject of great interest from point of view of magnetic application, since the fist compass to present date. In contrast, the scientific interest for iron based magnetic oxides decreased after Oersted discovery as they where replaced by coil as magnetizing sources. Neel discovery of ferrimagnetism boosted again interest and leads to strong developments during two decades before being of less interest. Recently, the evolution of power electronics toward higher frequency, the down sizing of ceramics microstructure to nanometer scale, the increasing price of rare-earth elements and the development of magnetocaloric materials put light again on ferrites. A review on three ferrite families is given herein: harder nanostructured Ba 2+ Fe 12 O 19 magnet processed by spark plasma sintering, magnetocaloric effect associated to the spin transition reorientation of W-ferrite and low temperature spark plasma sintered Ni-Zn-Cu ferrites for high frequency power applications.

Magnetic shielding for coreless linear permanent magnet motors

NARCIS (Netherlands)

Pluk, K.J.W.; Jansen, J.W.; Lomonova, E.

2013-01-01

This paper concerns the local reduction of the magnetic flux density by means of magnetic shielding. Using a spatial frequency description, a 2-D semi-analytical periodic model is obtained for a coreless single-sided linear permanent magnet motor. The magnetic shield is included in the modeling

Manganese ferrite prepared using reverse micelle process: Structural and magnetic properties characterization

Energy Technology Data Exchange (ETDEWEB)

Hashim, Mohd, E-mail: md.hashim09@gmail.com [Department of Physics, Aligarh Muslim University, Aligarh 202002 (India); Shirsath, Sagar E. [Spin Device Technology Centre, Department of Engineering, Shinshu University, Nagano 380-8553 (Japan); Meena, S.S. [Solid State Physics Division, Bhabha Atomic Research Centre, Mumbai 400085 (India); Mane, M.L. [Department of Physics, S.G.R.G. Shinde Mahavidyalaya, Paranda 413502, MS (India); Kumar, Shalendra [School of Materials Science and Engineering, Changwon National University, Changwon, Gyeongnam 641-773 (Korea, Republic of); Bhatt, Pramod [Solid State Physics Division, Bhabha Atomic Research Centre, Mumbai 400085 (India); Kumar, Ravi [Centre for Material Science Engineering, National Institute of Technology, Hamirpur, HP (India); Prasad, N.K.; Alla, S.K. [Deptartment of Metallurgical Engineering, Indian Institute of Technology (Banaras Hindu University), Varanasi 221005 (India); Shah, Jyoti; Kotnala, R.K. [National Physical Laboratory (CSIR), Dr. K.S. Krishnan Road, New Delhi 110012 (India); Mohammed, K.A. [Department of Mathematics & Physics Sciences, College of Arts and Sciences, University of Nizwa, Nizwa (Oman); Şentürk, Erdoğan [Department of Physics, Sakarya University, Esentepe, 54187 Sakarya (Turkey); Alimuddin [Department of Physics, Aligarh Muslim University, Aligarh 202002 (India)

2015-09-05

Highlights: • Preparation of Mn{sup 3+} substituted MnFe{sub 2}O{sub 4} ferrite by Reverse microemulsion process. • Characterization by XRD, SEM, VSM, Mössbauer spectroscopy and dielectric measurements techniques. • Magnetic properties of MnFe{sub 2}O{sub 4} enhanced after Mn{sup 3+} substitution. • The dielectric constant and ac conductivity increased with Mn{sup 3+} substitution. - Abstract: Reverse microemulsion process was employed to prepare of nanocrystalline Mn{sup 3+} substituted MnFe{sub 2−x}Mn{sub x}O{sub 4} ferrites. The structural, magnetic and dielectric properties were studied for different concentrations of Mn{sup 3+}. The structural and microstructural properties were analyzed using X-ray diffraction technique (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM) and Fourier transform infrared (FT-IR) spectroscopy techniques. The phase identification of the materials was studied by Rietveld refined XRD patterns which reveals single phase with cubic symmetry for the samples. The lattice parameters were ranged in between 8.369 and 8.379 Å and do not show any significant change with the substitution of Mn{sup 3+}. The average particles size was found to be around 11 ± 3 nm. Magnetization results obtained from the vibrating sample magnetometer (VSM) confirm that the substitution of Mn{sup 3+} in MnFe{sub 2}O{sub 4} ferrite caused an increase in the saturation magnetization and coercivity. The dependence of Mössbauer parameters on Mn{sup 3+} substitution has been analyzed. Magnetic behavior of the samples were also studied at field cooled (FC) and zero field cooled (ZFC) mode. The dependence of Mössbauer parameters on Mn{sup 3+} substitution was also analyzed. All the magnetic characterization shows that Mn{sup 3+} substitution enhance the magnetic behavior of MnFe{sub 2}O{sub 4} ferrite nanoparticles.

Method and apparatus for assembling permanent magnet rotors

Science.gov (United States)

Hsu, J.S.; Adams, D.J.

1999-06-22

A permanent magnet assembly for assembly in large permanent magnet motors and generators includes a two-piece carrier that can be slid into a slot in the rotor and then secured in place using a set screw. The invention also provides an auxiliary carrier device with guide rails that line up with the teeth of the rotor, so that a permanent magnet assembly can be pushed first into a slot, and then down the slot to its proper location. An auxiliary tool is provided to move the permanent magnet assembly into position in the slot before it is secured in place. Methods of assembling and disassembling the magnet assemblies in the rotor are also disclosed. 2 figs.

Permanent Magnet Dipole for DIRAC Design Report

CERN Document Server

Vorozhtsov, Alexey

2012-01-01

Two dipole magnets including one spare unit are needed for the for the DIRAC experiment. The proposed design is a permanent magnet dipole. The design based on Sm2Co17 blocks assembled together with soft ferromagnetic pole tips. The magnet provides integrated field strength of 24.6 10-3 T×m inside the aperture of 60 mm. This Design Report summarizes the main magnetic and mechanic design parameters of the permanent dipole magnets.

Magnetic Properties of Copper Doped Nickel Ferrite Nanoparticles Synthesized by Co Precipitation Method

Science.gov (United States)

Anjana, V.; John, Sara; Prakash, Pooja; Nair, Amritha M.; Nair, Aravind R.; Sambhudevan, Sreedha; Shankar, Balakrishnan

2018-02-01

Nickel ferrite nanoparticles with copper atoms as dopant have been prepared using co-precipitation method with general formula Ni1-xCuxFe2O4 (x=0.2, 0.4, 0.6, 0.8 and 1) and are sintered at quite ambient temperature. Structural and magnetic properties were examined using Fourier Transform Infrared Spectroscopy (FTIR), X-ray Diffraction method (XRD) and Vibrating Sample Magnetometer (VSM) to study the influence of copper doping in nickel ferrite magnetic nanoparticles. X-ray studies proves that the particles are possessing single phase spinel structure with an average particle size calculated using Debye Scherer formula. Magnetic measurements reveal that saturation magnetization value (Ms) decreases while magnetic coercivity (Hc) increases upon doping.

A new application and experimental validation of moulding technology for ferrite magnet assisted synchronous reluctance machine

DEFF Research Database (Denmark)

Wu, Qian; Lu, Kaiyuan; Rasmussen, Peter Omand

2016-01-01

This paper introduces a new application of moulding technology to the installation of ferrite magnet material into the rotor flux barriers of Ferrite Magnet Assisted Synchronous Reluctance Machine (FASynRM). The feasibility of this application with respect to manufacturing process and motor...

Ferrites and ceramic composites

CERN Document Server

Jotania, Rajshree B

2013-01-01

The Ferrite term is used to refer to all magnetic oxides containing iron as major metallic component. Ferrites are very attractive materials because they simultaneously show high resistivity and high saturation magnetization, and attract now considerable attention, because of the interesting physics involved. Typical ferrite material possesses excellent chemical stability, high corrosion resistivity, magneto-crystalline anisotropy, magneto-striction, and magneto-optical properties. Ferrites belong to the group of ferrimagnetic oxides, and include rare-earth garnets and ortho-ferrites. Several

Structure and magnetic field of periodic permanent magnetic focusing system with open magnetic rings

International Nuclear Information System (INIS)

Peng Long; Li Lezhong; Yang Dingyu; Zhu Xinghua; Li Yuanxun

2011-01-01

The magnetic field along the central axis for an axially magnetized permanent magnetic ring was investigated by analytical and finite element methods. For open magnetic rings, both calculated and measured results show that the existence of the radial magnetic field creates a remarkable cosine distribution field along the central axis. A new structure of periodic permanent magnet focusing system with open magnetic rings is proposed. The structure provides a satisfactory magnetic field with a stable peak value of 120 mT for a traveling wave tube system. - Research highlights: → For open magnetic rings, both calculated and measured results show that the existence of the radial magnetic field creates a remarkable cosine distribution field along the central axis. → A new structure of periodic permanent magnet (PPM) focusing system with open magnetic rings is proposed. → The new PPM focusing system with open magnetic rings meets the requirements for TWT system.

Using axial magnetized permanent rings to build axial gradient magnetic field

International Nuclear Information System (INIS)

Peng Quanling

2003-01-01

Axial field produced by an axially magnetized permanent ring was studied. For two permanent magnet rings, if they are magnetized in the same direction, a nearly uniform axial field can be produced; if they are magnetized in opposite direction, an axial gradient field can be produced in the region between the two permanent rings, with the field strength changing from -B 0 to B 0 . A high gradient axial magnetic field has been built by using two axially magnetized permanent rings, the measured field results agree with the PANDIRA calculation very well. It is desirable that the field gradient can be varied to match various requirements. A method to produce the variable gradient field is presented. Axial gradient field can also be used as a beam focusing facility for linear accelerator if axial periodic field can be produced. Its magnetic field is similar to that of a solenoid, in which, large stray field will leak to the outside environment. A method for shielding the outside stray field is discussed

Rotor for a line start permanent magnet machine

Science.gov (United States)

Melfi, Mike; Schiferl, Rich; Umans, Stephen

2017-07-11

A rotor comprises laminations with a plurality of rotor bar slots with an asymmetric arrangement about the rotor. The laminations also have magnet slots equiangularly spaced about the rotor. The magnet slots extend near to the rotor outer diameter and have permanent magnets disposed in the magnet slots creating magnetic poles. The magnet slots may be formed longer than the permanent magnets disposed in the magnets slots and define one or more magnet slot apertures. The permanent magnets define a number of poles and a pole pitch. The rotor bar slots are spaced from adjacent magnet slots by a distance that is at least 4% of the pole pitch. Conductive material is disposed in the rotor bar slots, and in some embodiments, may be disposed in the magnet slot apertures.

Magnetization reversal processes in bonded magnets made from a mixture of Nd–(Fe,Co)–B and strontium ferrite powders

International Nuclear Information System (INIS)

Dospial, M.; Plusa, D.

2013-01-01

Isotropic epoxy-resin bonded magnets composed of different amounts of Magnequench MQP-B and strontium ferrite powders have been prepared using a compression molding technique. The magnetic parameters for magnets with different amounts of strontium ferrite and magnetization reversal processes have been studied by the measurement of the initial magnetization curves, the major hysteresis loops measured at a field up to 14 T and sets of recoil loops. The enhancement of μ 0 M R and μ 0 H C is observed in comparison with the calculated values. From the recoil loops the field dependences of the reversible, irreversible and total magnetization components and the differential susceptibilities were derived. From the dependence of the irreversible magnetization component versus an applied field it was deduced that the main mechanism of magnetization reversal process is the pinning of domain walls in MQP-B and strontium ferrite grains. The interactions between the magnetic particles and grains have been examined by the analysis of the δM plot. The δM behavior of magnets with ferrite has been interpreted as being composed of magnetizing exchange coupling and demagnetizing dipolar interactions. - Highlights: ► SrFe 12 O 19 addition causes a decrease in the H c , J R and (BH) max . ► H c and J R changes are not in agreement with dilution law. ► Main mechanism of the coercivity is the pinning of domain walls. ► In both magnets from pure powders dominant role plays long range dipolar interactions. ► Dipolar and exchange interaction are simultaneously present in hybrids but the dipolar are weaker.

Permanent magnet design for magnetic heat pumps using total cost minimization

Science.gov (United States)

Teyber, R.; Trevizoli, P. V.; Christiaanse, T. V.; Govindappa, P.; Niknia, I.; Rowe, A.

2017-11-01

The active magnetic regenerator (AMR) is an attractive technology for efficient heat pumps and cooling systems. The costs associated with a permanent magnet for near room temperature applications are a central issue which must be solved for broad market implementation. To address this problem, we present a permanent magnet topology optimization to minimize the total cost of cooling using a thermoeconomic cost-rate balance coupled with an AMR model. A genetic algorithm identifies cost-minimizing magnet topologies. For a fixed temperature span of 15 K and 4.2 kg of gadolinium, the optimal magnet configuration provides 3.3 kW of cooling power with a second law efficiency (ηII) of 0.33 using 16.3 kg of permanent magnet material.

Magnetic properties of nanostructured spinel ferrites and ...

Indian Academy of Sciences (India)

exchange interaction strength because of an increase in the magnetic ion concentration in the A-site on milling, ... By using a copper wheel, rotating with the ... Zn ferrite with a small applied field of 4 mT for two different grain sizes. The Néel ... By varying the concentration of the oxidant (KNO3) or ferric ions, we could achieve.

Ce-didymium-Fe-B sintered permanent magnets

International Nuclear Information System (INIS)

Homma, M.; Okada, M.; Sugimoto, S.

1985-01-01

Present works report the development of the low cost R-Fe-B permanent magnets. The best magnetic properties obtained in this studies are Br=13.5 kG, iHc=10.2 kOe and (BH)max=40 MGOe with an Fe-33.5wt%(5Ce-Didymium)-1wt% B alloy. Topics considered in this paper include cerium alloys, boron alloys, fabrication, capitalized cost, iron alloys, permanent magnets, and magnetic properties

Calculation and Analysis of Permanent Magnet Eddy Current Loss Fault with Magnet Segmentation

Directory of Open Access Journals (Sweden)

Bing Li

2016-01-01

Full Text Available This paper investigates the problem of calculating and analyzing the effect of the permanent magnet eddy current loss fault due to magnet segmentation. Taking an interior permanent magnet synchronous motor with inverter supplied as an example, the rated power of motor was 2.2 kW. Three-dimensional finite-element model was firstly established based on finite-element software. Then, the model mesh and boundary conditions were handled specially; permanent magnet eddy current loss fault was calculated and analyzed theoretically with magnet segmentation from space harmonic and time harmonic, respectively. Finally, calculation results were compared and explained. A useful conclusion for permanent magnet synchronous motor design has been obtained.

Hydrogen stability of SmCo5 permanent magnet

International Nuclear Information System (INIS)

Lukin, A.; Rabinovich, Y.; Bala, H.

2001-01-01

The present work has been performed with purpose to determine the level of hydrogen stability of sintered SmCo 5 permanent magnets by means of accelerated tests, to study the effect of hydrogen on the magnetic and mechanical properties of the permanent magnets and to establish the criteria of hydrogenation level and the activation energy of this process. In addition, the effect of hydrogen on the properties of sintered SmCo 5 permanent magnets in specific conditions of exploitation and storage durability of instruments was studied

Permanent magnets and its production by powder metallurgy

Directory of Open Access Journals (Sweden)

Enrique Herraiz Lalana

2018-06-01

Full Text Available In this work, the historical relationship between permanent magnets and powder metallurgy is reviewed. Powder metallurgy is a manufacturing technique based on the compaction of powders that are sintered to create a solid product. This technique was used in the production of permanent magnets for the first time in the 18th century and, nowadays, most permanent magnetic materials are manufacturing by this mean. Magnetic properties are highly dependent on the microstructure of the final product, the magnetic alignment of domains and presence of porosity, to mention a few, and powder metallurgy enables fine control of these factors.

Nickel ferrite nanoparticles: elaboration in polyol medium via hydrolysis, and magnetic properties

Energy Technology Data Exchange (ETDEWEB)

Chkoundali, S [ITODYS, UMR-CNRS 7086, Universite Paris 7, 2 Place Jussieu (case 7090), 75251 Paris (France); Ammar, S [ITODYS, UMR-CNRS 7086, Universite Paris 7, 2 Place Jussieu (case 7090), 75251 Paris (France); Jouini, N [ITODYS, UMR-CNRS 7086, Universite Paris 7, 2 Place Jussieu (case 7090), 75251 Paris (France); Fievet, F [ITODYS, UMR-CNRS 7086, Universite Paris 7, 2 Place Jussieu (case 7090), 75251 Paris (France); Molinie, P [Institut Jean Rouxel des Materiaux, 2 Chemin de la Houssiniere, 44072 Nantes (France); Danot, M [Institut Jean Rouxel des Materiaux, 2 Chemin de la Houssiniere, 44072 Nantes (France); Villain, F [LI2M, UMR-CNRS 7071, Universite Paris 6, 4 Place Jussieu (case 42), 75252 Paris (France); Greneche, J-M [LPEC, UMR-CNRS 6087, Universite du Maine, Avenue O Messiaen, 72085 Le Mans (France)

2004-06-23

Ultrafine magnetic nickel ferrite NiFe{sub 2}O{sub 4} particles of high crystallinity were directly prepared by forced hydrolysis of ionic iron (III) and nickel (II) solutions in 2-hydroxyethyl ether at about 478 K under atmospheric pressure. The resulting nickel ferrite particles exhibit very interesting magnetic properties: they are superparamagnetic at room temperature and have a saturation magnetization close to that of the bulk at low temperature. An in-field Moessbauer study shows clearly that this surprising behaviour is mainly due to: (i) a departure of the cation distribution from the classical distribution encountered in the bulk material and (ii) the absence of spin canting for both tetrahedral and octahedral cations.

Influence of La3+ Substitution on Structure, Morphology and Magnetic Properties of Nanocrystalline Ni-Zn Ferrite.

Directory of Open Access Journals (Sweden)

Y K Dasan

Full Text Available Lanthanum substituted Ni-Zn ferrite nanoparticles (Ni0.5Zn0.5LaxFe1-xO4; 0.00 ≤x≤ 1.00 synthesized by sol-gel method were presented. X-ray diffraction patterns reveal the typical single phase spinel cubic ferrite structure, with the traces of secondary phase for lanthanum substituted nanocrystals. In addition, the structural analysis also demonstrates that the average crystallite size varied in the range of 21-25 nm. FTIR spectra present the two prominent absorption bands in the range of 400 to 600 cm-1 which are the fingerprint region of all ferrites. Surface morphology of both substituted and unsubstituted Ni-Zn ferrite nanoparticle samples was studied using FESEM technique and it indicates a significant increase in the size of spherical shaped particles with La3+ substitution. Magnetic properties of all samples were analyzed using vibrating sample magnetometer (VSM. The results revealed that saturation magnetization (Ms and coercivity (Hc of La3+ substituted samples has decreased as compared to the Ni-Zn ferrite samples. Hence, the observed results affirm that the lanthanum ion substitution has greatly influenced the structural, morphology and magnetic properties of Ni-Zn ferrite nanoparticles.

Modeling demagnetization effects in permanent magnet synchronous machines

NARCIS (Netherlands)

Kral, C.; Sprangers, R.L.J.; Waarma, J.; Haumer, A.; Winter, O.; Lomonova, E.

2010-01-01

This paper presents a permanent magnet model which takes temperature dependencies and demagnetization effects into account. The proposed model is integrated into a magnetic fundamental wave machine model using the model- ing language Modelica. For different rotor types permanent magnet models are

Magnetic forces between arrays of cylindrical permanent magnets

Czech Academy of Sciences Publication Activity Database

Vokoun, David; Tomassetti, G.; Beleggia, M.; Stachiv, Ivo

2011-01-01

Roč. 323, č. 1 (2011), s. 55-60 ISSN 0304-8853 R&D Projects: GA ČR(CZ) GA101/09/0702 Institutional research plan: CEZ:AV0Z10100520 Keywords : magnetism * permanent magnets Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 1.780, year: 2011

Magnetic heating by silica-coated Co–Zn ferrite particles

Czech Academy of Sciences Publication Activity Database

Veverka, Miroslav; Závěta, K.; Kaman, Ondřej; Veverka, Pavel; Knížek, Karel; Pollert, Emil; Burian, M.; Kašpar, P.

2014-01-01

Roč. 47, č. 6 (2014), "065503-1"-"065503-11" ISSN 0022-3727 R&D Projects: GA ČR GAP204/10/0035; GA ČR(CZ) GAP108/11/0807 Institutional support: RVO:68378271 Keywords : cobalt–zinc ferrite * magnetic nanoparticles * coprecipitation * silica coating * hysteresis loops * calorimetric measurements * hyperthermia Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 2.721, year: 2014 http://stacks.iop.org/0022-3727/47/065503

Effect of gamma irradiation on the structural and magnetic properties of Co–Zn spinel ferrite nanoparticles

International Nuclear Information System (INIS)

Raut, Anil V.; Kurmude, D.V.; Shengule, D.R.; Jadhav, K.M.

2015-01-01

Highlights: • Co–Zn ferrite nanoparticles were examined before and after γ-irradiation. • Single phase cubic spinel structure of Co–Zn was confirmed by XRD data. • The grain size was reported in the range of 52–62 nm after γ-irradiation. • Ms, Hc, n B were reported to be increased after gamma irradiation. - Abstract: In this work, the structural and magnetic properties of Co 1−x Zn x Fe 2 O 4 (0.0 ≤ x ≤ 1.0) ferrite nanoparticles were studied before and after gamma irradiation. The as-synthesized samples of Co–Zn ferrite nanoparticles prepared by sol–gel auto-combustion technique were analysed by XRD which suggested the single phase; cubic spinel structure of the material. Crystal defects produced in the spinel lattice were studied before and after Co 60 γ-irradiation in a gamma cell with a dose rate of 0.1 Mrad/h in order to report the changes in structural and magnetic properties of the Co–Zn ferrite nanoparticles. The average crystallite size (t), lattice parameter (α) and other structural parameters of gamma-irradiated and un-irradiated Co 1−x Zn x Fe 2 O 4 spinel ferrite system was calculated from XRD data. The morphological characterizations were performed using scanning electron microscopy (SEM). The magnetic properties were measured using pulse field hysteresis loop tracer by applying magnetic field of 1000 Oe, and the analysis of data obtained revealed that the magnetic property such as saturation magnetization (Ms), coecivity (Hc), magneton number (n B ) etc. magnetic parameters were increased after irradiation

Magnetic losses and instabilities in ferrite garnet tuned RF cavities for synchrotrons

International Nuclear Information System (INIS)

Shapiro, V.E.

1994-01-01

The aim of this paper is to introduce basic notions and elucidate the main features of magnetic losses and nonlinear effects in high power rf cavities with perpendicularly biased ferrite garnet used for varying the frequency in rapid cycling synchrotrons. A method of analysis is developed using a minimum of specific details. Simple formulae and estimates of the trend of magnetic loss, nonlinear frequency shift and possible instabilities in the cavities as a function of rf power level and ferrite garnet parameters are presented. Numerical examples correspond to the TRIUMF KAON Booster synchrotron. (author). 14 refs., 5 figs

Magnetostatic interactions and forces between cylindrical permanent magnets

International Nuclear Information System (INIS)

Vokoun, David; Beleggia, Marco; Heller, Ludek; Sittner, Petr

2009-01-01

Permanent magnets of various shapes are often utilized in magnetic actuators, sensors or releasable magnetic fasteners. Knowledge of the magnetic force is required to control devices reliably. Here, we introduce an analytical expression for calculating the attraction force between two cylindrical permanent magnets on the assumption of uniform magnetization. Although the assumption is not fulfilled exactly in cylindrical magnets, we obtain a very good agreement between the calculated and measured forces between two identical cylindrical magnets and within an array of NdFeB cylindrical magnets.

Numerical simulation of magnetic convection ferrofluid flow in a permanent magnet-inserted cavity

Science.gov (United States)

Ashouri, Majid; Behshad Shafii, Mohammad

2017-11-01

The magnetic convection heat transfer in an obstructed two-dimensional square cavity is investigated numerically. The walls of the cavity are heated with different constant temperatures at two sides, and isolated at two other sides. The cavity is filled with a high Prandtl number ferrofluid. The convective force is induced by a magnetic field gradient of a thermally insulated square permanent magnet located at the center of the cavity. The results are presented in the forms of streamlines, isotherms, and Nusselt number for various values of magnetic Rayleigh numbers and permanent magnet size. Two major circulations are generated in the cavity, clockwise flow in the upper half and counterclockwise in the lower half. In addition, strong circulations are observed around the edges of the permanent magnet surface. The strength of the circulations increase monotonically with the magnetic Rayleigh number. The circulations also increase with the permanent magnet size, but eventually, are suppressed for larger sizes. It is found that there is an optimum size for the permanent magnet due to the contrary effects of the increase in magnetic force and the increase in flow resistance by increasing the size. By increasing the magnetic Rayleigh number or isothermal walls temperature ratio, the heat transfer rate increases.

Topology optimization for design of segmented permanent magnet arrays with ferromagnetic materials

Science.gov (United States)

Lee, Jaewook; Yoon, Minho; Nomura, Tsuyoshi; Dede, Ercan M.

2018-03-01

This paper presents multi-material topology optimization for the co-design of permanent magnet segments and iron material. Specifically, a co-design methodology is proposed to find an optimal border of permanent magnet segments, a pattern of magnetization directions, and an iron shape. A material interpolation scheme is proposed for material property representation among air, permanent magnet, and iron materials. In this scheme, the permanent magnet strength and permeability are controlled by density design variables, and permanent magnet magnetization directions are controlled by angle design variables. In addition, a scheme to penalize intermediate magnetization direction is proposed to achieve segmented permanent magnet arrays with discrete magnetization directions. In this scheme, permanent magnet strength is controlled depending on magnetization direction, and consequently the final permanent magnet design converges into permanent magnet segments having target discrete directions. To validate the effectiveness of the proposed approach, three design examples are provided. The examples include the design of a dipole Halbach cylinder, magnetic system with arbitrarily-shaped cavity, and multi-objective problem resembling a magnetic refrigeration device.

Magnetic and electrical properties of Cr substituted Ni nano ferrites

Directory of Open Access Journals (Sweden)

Katrapally Vijaya Kumar

2018-03-01

Full Text Available Nano-ferrites with composition NiCrxFe2-xO4 (where x = 0.1, 0.3, 0.5, 0.7, 0.9, 1.0 were synthesized through citrate-gel auto combustion technique at moderately low temperature. X-ray analysis shows cubic spinel structure single phase without any impurity peak and average crystallite size in the range 8.5–10.5 nm. Magnetic properties were measured using a vibrating sample magnetometer at room temperature in the applied field of ±6 KOe. The obtained M-H loop area is very narrow, hence the synthesized nano ferrites are soft magnetic materials with small coercivity. Magnetic parameters such as saturation magnetization (Ms, coercivity (Hc, remanent magnetization (Mr and residual magnetization were measured and discussed with regard to Cr3+ ion concentration. Electrical properties were measured using two probe method from room temperature to well beyond transition temperature. The DC resistivity variation with temperature shows the semiconductor nature. Resistivity, drift mobility and activation energy values are measured and discussed with regard to composition. The Curie temperature was determined using DC resistivity data and Loria-Sinha method. The observed results can be explained in detail on the basis of composition.

Development of cryogenic permanent magnet undulator

International Nuclear Information System (INIS)

Hara, Toru; Tanaka, Takashi; Shirasawa, Katsutoshi; Kitamura, Hideo; Bizen, Teruhiko; Seike, Takamitsu; Marechal, Xavier; Tsuru, Rieko; Iwaki, Daisuke

2005-01-01

A short period undulator increases not only the photon energy of undulator radiation, but also the brilliance due to its increased number of undulator periods. As a result, brilliant undulator radiation becomes available in the photon energy range, which is currently covered by wigglers. In order to develop a short period undulator, high performance magnets are indispensable and superconductive undulators have been actively investigated in recent years. In this paper, however, we propose a new approach, so called a cryogenic permanent magnet undulator using NdFeB magnets at the temperatures around 150 K. The current status of this cryogenic permanent magnet undulator development at SPring-8 is presented including the results of the magnetic field measurements on a prototype undulator. (author)

Magnetic susceptibility of MnZn and NiZn soft ferrites using Laplace transform and the Routh-Hurwitz criterion

International Nuclear Information System (INIS)

Fano, Walter Gustavo; Boggi, Silvina; Razzitte, Adrian Cesar

2011-01-01

This paper is devoted to study the Routh-Hurwitz stability criterion from the MnZn and NiZn soft ferrites using a phenomenological model with the gyromagnetic spin contribution and domain wall contribution. The magnetodynamic equation and the harmonic oscillator equation have been used to obtain the domain walls and the spin contribution of the magnetic susceptibility. The ferrite materials have been considered as linear, time invariant, isotropic and homogeneous, and the magnetization vector is proportional to the magnetic field vector. The resulting expression of the magnetization in time domain of both ferrites under study has been obtained by mean of the inverse Laplace transformation applying the residue method. The poles of the magnetic susceptibility have negative real parts, which ensures that the response decays exponentially to zero as the time increase. The degree of the numerator's polynomial of the magnetic susceptibility is less than the degree of denominator's polynomial in the magnetic susceptibility function: and the poles are located in the half left s-plane. Then the system is bounded-input, bounded-output (BIBO), and the results agree with the Routh-Hurwitz stability criterion for the MnZn and NiZn soft ferrites. - Research Highlights: → Laplace transform of the magnetic susceptibility of the MnZn and NiZn soft ferrites. → Routh-Hurwitz stability criterion of magnetic materials. → Bode plot of magnetic susceptibility. → Inverse Laplace transform using residue theorem.

The dynamic behavior of magnetic fluid adsorbed to small permanent magnet in alternating magnetic field

Energy Technology Data Exchange (ETDEWEB)

Sudo, Seiichi, E-mail: sudo@akita-pu.ac.j [Faculty of Systems Science and Technology, Akita Prefectural University, Ebinokuchi 84-4, Yurihonjo 015-0055 (Japan); Asano, Daisaku [Faculty of Systems Science and Technology, Akita Prefectural University, Ebinokuchi 84-4, Yurihonjo 015-0055 (Japan); Takana, Hidemasa; Nishiyama, Hideya [Institute of Fluid Science, Tohoku University, Katahira 2-1-1, Aobaku, Sendai 980-8577 (Japan)

2011-05-15

The dynamic behavior of a magnetic fluid adsorbed to a small NdFeB permanent magnet subjected to an alternating magnetic field was studied with a high speed video camera system. The directions of alternating magnetic field are parallel and opposite to that of the permanent magnet. It was found that the surface of magnetic fluid responds to the external alternating magnetic field in elongation and contraction with a lot of spikes. Generation of a capillary magnetic fluid jet was observed in the neighbourhood of a specific frequency of alternating field. The effect of gravitational force on surface phenomena of magnetic fluid adsorbed to the permanent magnet was revealed. - Research Highlights: Magnetic fluid of the system responds to alternating magnetic field with higher frequencies. Large-amplitude surface motions of magnetic fluid occur at the specific frequencies of the external field. Capillary jets of magnetic fluid are generated at the natural frequency of the system.

Enlargement of Tuning Range in a Ferrite-Tuned Cavity Through Superposed Orthogonal and Parallel Magnetic Bias

CERN Document Server

Vollinger, C

2013-01-01

Conventional ferrite-tuned cavities operate either with bias fields that are orthogonal or parallel to the magnetic RF-field. For a cavity that tunes rapidly over an overall frequency range around 100-400 MHz with high Q, we use ferrite garnets exposed to an innovative new biasing method consisting of a superposition of perpendicular and parallel magnetic fields. This method leads to a significant enlargement of the high-Q cavity tuning range by defining an operation point close to the magnetic saturation and thus improving ferrite material behaviour. A further advantage of this technique is the fast tuning speed resulting from the fact that tuning is carried out either with pure parallel biasing, or together with a very small change of operating point from perpendicular bias. In this paper, several scaled test models of ferrite-filled resonators are shown; measurements on the set-ups are compared and discussed.

Performance analysis of a new radial-axial flux machine with SMC cores and ferrite magnets

Science.gov (United States)

Liu, Chengcheng; Wang, Youhua; Lei, Gang; Guo, Youguang; Zhu, Jianguo

2017-05-01

Soft magnetic composite (SMC) is a popular material in designing of new 3D flux electrical machines nowadays for it has the merits of isotropic magnetic characteristic, low eddy current loss and high design flexibility over the electric steel. The axial flux machine (AFM) with the extended stator tooth tip both in the radial and circumferential direction is a good example, which has been investigated in the last years. Based on the 3D flux AFM and radial flux machine, this paper proposes a new radial-axial flux machine (RAFM) with SMC cores and ferrite magnets, which has very high torque density though the low cost low magnetic energy ferrite magnet is utilized. Moreover, the cost of RAFM is quite low since the manufacturing cost can be reduced by using the SMC cores and the material cost will be decreased due to the adoption of the ferrite magnets. The 3D finite element method (FEM) is used to calculate the magnetic flux density distribution and electromagnetic parameters. For the core loss calculation, the rotational core loss computation method is used based on the experiment results from previous 3D magnetic tester.

Magnetic and microstructural properties of Ni-Zn ferrites synthesized and sintered by microwave energy; Propriedades magneticas e microestruturais de ferritas Ni-Zn sintetizadas e sinterizadas oir energia de microondas

Energy Technology Data Exchange (ETDEWEB)

Vieira, D.A.; Diniz, V.C.S.; Sousa, J-P.LM.L.; Costa, A.C.F.M. [Universidade Federal de Campina Grande (UFCG), PB (Brazil). Dept. de Engenharia de Materiais; Kiminami, R.H.G.A. [Universidade Federal de Sao Carlos (UFScar), SP (Brazil). Dept. de Engenharia de Materiais; Cornejo, D.R. [Universidade de Sao Paulo (IF/USP), SP (Brazil). Inst. de Fisica

2009-07-01

The soft ferrites (or soft) and the Ni-Zn type are composed of spinel with cubic structure, which exhibit a permanent magnetization, called ferrimagnetism. Thus, this work will be assessed the structure and magnetic properties of ferrites Ni{sub 0},{sub 5}Zn{sub 0},{sub 5}Fe{sub 2}O{sub 4} prepared by combustion reaction using microwave energy as a source of heat and urea as fuel and after sintering by microwave energy. The synthesized powders were compacted by uniaxial pressing. The synthesized powders and the samples after sintering were characterized by XRD, SEM and magnetic measures. The diffractogram X-ray powder and the sintered samples showed the presence of the desired phase Ni{sub 0},{sub 5}Zn{sub 0},{sub 5}Fe{sub 2}O{sub 4} in both cases. The powders and sintered samples resulted in the Ms value of 8.09 emu/g and 67.73 emu/g, respectively. (author)

Structural, magnetic and dielectric investigations in antimony doped nano-phased nickel-zinc ferrites

Energy Technology Data Exchange (ETDEWEB)

Lakshmi, Ch.S. [Department of Physics, Regency Institute of Technology, Adivipolam Yanam 533464, Pondicherry (India); Sridhar, Ch.S.L.N. [Department of Physics, Vignana Bharathi Institute of Technology, Aushapur(v) Ghatkesar (M), Hyderabad 501301, Telangana (India); Govindraj, G. [Department of Physics, School of Physical, Chemical and Applied Sciences, Pondicherry University, R.V.Nagar, Kalapet, Pondicherry 605014 (India); Bangarraju, S. [Department of Physics, Andhra University, Visakhapatnam 530003, Andhrapradesh (India); Potukuchi, D.M., E-mail: potukuchidm@yahoo.com [Department of Physics, University College of Engineering, Jawaharlal Nehru Technological University:Kakinada, Kakinada 533003 (India)

2015-02-15

Nanocrystalline Ni–Zn–Sb ferrites synthesized by hydrothermal method are reported. Influence of Sb{sup 5+} ions on structural, magnetic and dielectric properties of ferrites is studied. Phase identification, lattice parameter and crystallite size studies are carried out using by X-ray diffraction (XRD). Addition of dopant resulted for decrease in lattice parameter. Crystallite size gets reduced from 62 nm to 38 nm with doping of Antimony. Crystallite size and porosity exhibit similar trends with doping. Morphological study is carried out by Field Emission Scanning Electron Microscopy (FESEM). Strong FTIR absorption bands at 400–600 cm{sup −1} confirm the formation of ferrite structure. Increase of porosity is attributed to the grain size. Doping with Antimony results for decrease in saturation magnetization and increase in coercivity. An initial increase of saturation magnetization for x=0.1 is attributed to the unusually high density. Reversed trend of coercivity with crystallite size are observed. Higher value of dielectric constant ε′(ω) is attributed to the formation of excess of Fe{sup 2+} ions caused by aliovalent doping of Sb{sup 5+} ions. Variation of dielectric constant infers hopping type of conductivity mechanism. The dielectric loss factor tanδ attains lower values of ∼10{sup −2}. High ac resistivity ρ(ω) of 10{sup 8} Ω cm is witnessed for antimony doped ferrites. Higher saturation magnetization and enhanced dielectric response directs for a possible utility as microwave oscillators and switches.

Two cylinder permanent magnet stirrer for liquid metals

Science.gov (United States)

Bojarevičs, A.; Baranovskis, R.; Kaldre, I.; Milgrāvis, M.; Beinerts, T.

2017-07-01

To achieve a uniform liquid metal composition and temperature distribution, stirring is often necessary for industrial processes. Here, a novel permanent magnet system for liquid melt stirring is proposed. It promises very low energy consumption and options for multiple different flow types compared to traditional travelling magnetic field inductors or mechanical stirrers. The proposed system has a simple design: it consists of two rotating permanent magnet cylinders, which are magnetized transversely to the axis of the cylinders. The experimental device was developed and tested under various regimes using GaInSn alloy in a cylindrical crucible. Aluminum stirring by permanent magnets in laboratory scale is tested, and stirring impact on directional solidification of metallic alloys is experimentally investigated.

Structural and magnetic properties of Co-substituted NiCu ferrite nanopowders

Energy Technology Data Exchange (ETDEWEB)

Li, Le-Zhong, E-mail: lezhongli@cuit.edu.cn; Zhong, Xiao-Xi; Wang, Rui; Tu, Xiao-Qiang; Peng, Long

2017-07-01

Highlights: • There are Fe{sub 2}O{sub 3} and CuO impurity phases when x ≤ 0.10. • The saturation magnetization and coercivity monotonically increase with the increase of Co substitution. • The anisotropy constant increases with the increase of Co substitution. • The calculated and observed values of magneton number are in close agreement with each other. - Abstract: Co-substituted NiCu ferrite nanopowders with the chemical formula Ni{sub 0.5−x}Cu{sub 0.5−x}Co{sub 2x}Fe{sub 2}O{sub 4} (0 ≤ x ≤ 0.50) were synthesized by sol-gel auto-combustion method. The effects of Co substitution on the cation distribution, structural and magnetic properties of the NiCu ferrite nanopowders have been investigated. Differential thermal analysis-thermogravimetry (DTA-TG), X-ray diffraction (XRD), transmission electron microscope (TEM) and vibrating sample magnetometer (VSM) measurements were used to characterize the chemical, structural and magnetic properties of the ferrite nanopowders, respectively. The DTA-TG results indicate that there are three steps of the combustion process. XRD results indicate that there are Fe{sub 2}O{sub 3} and CuO impurity phases when x ≤ 0.10. Furthermore, the lattice parameter increases, and the X-ray density and the average crystallite size decrease with increasing Co substitution. And the obtained particle size from TEM image is in very good agreement with the average crystallite size estimated by XRD measurements. The saturation magnetization and coercivity monotonically increase with the increase of Co substitution. The increase of the saturation magnetization is due to the substitution of Ni{sup 2+} and Cu{sup 2+} ions with lower magnetic moment by Co{sup 2+} ions with higher magnetic moment on the octahedral sites. And the increase of the coercivity is mainly due to the increase of magnetocrystalline anisotropy energy.

Some economic aspects of rare-earth permanent magnets

International Nuclear Information System (INIS)

Zijlstra, H.

1978-01-01

The commercial feasibility of RE permanent magnets is analyzed in terms of price per unit of magnetostatic energy. The availability of the raw materials is also taken into consideration. The conclusion is that RE magnets are and remain relatively expensive as compared with other permanent magnets, and will find only limited application. (author)

Superconducting permanent magnets

International Nuclear Information System (INIS)

Wipf, S.L.; Laquer, H.L.

1989-01-01

The concept of superconducting permanent magnets with fields trapped in shells or cylinders of Type II superconductors is an old one. Unfortunately, the low values of 0.5 to 1T for the first flux jump field, which is independent of the actual current density, have frustrated its implementation with classical Type II superconductors. The fact that the flux jump fields for high temperature superconductors should be an order of magnitude larger at liquid nitrogen temperatures allows us to reconsider these options. Analysis of the hysteresis patterns, based on the critical state model, shows that, if the dimensions are chosen so that the sample is penetrated at a field B/sub p/, which is equal to or just less than the first flux jump field, B/sub fj/, a temporarily applied field of 2B/sub fj/ will trap 0.5 B/sub fj/. Thus for a 90 K superconductor with a B/sub fj/ of 6T, a permanent field of 3 T should be trapped, with an energy product of 1.8 MJ/m/sup 3/ (225 MG . Oe). This is five times as large as for the best permanent magnet materials. The authors discuss means to verify the analysis and the limitations imposed by the low critical current densities in presently available high temperature superconductors

Magnetizing of permanent magnet using HTS bulk magnet

International Nuclear Information System (INIS)

Oka, Tetsuo; Muraya, Tomoki; Kawasaki, Nobutaka; Fukui, Satoshi; Ogawa, Jun; Sato, Takao; Terasawa, Toshihisa

2011-01-01

A demagnetized Nd-Fe-B permanent magnet was scanned just above the magnetic pole containing the HTS bulk magnet, generating a magnetic field of 3.27 T. The magnet sample was subsequently found to be fully magnetized in the open space of the static magnetic fields. We examined the magnetic field distributions when the magnetic poles were scanned twice to activate the magnetic plates inversely with various overlap distances between the tracks of the HTS bulk magnet. The magnetic field of the 'rewritten' magnet reached the values of the magnetically saturated region of the material, showing steep gradients at the border of each magnetic pole. As a replacement for conventional pulse field magnetizing methods, this technique is proposed to expand the degree of freedom in the design of electromagnetic devices, and is proposed as a novel practical method for magnetizing rare-earth magnets, which have excellent magnetic performance and require intense fields of more than 3 T to be activated. (author)

Design of permanent magnet synchronous motor within minimum cost

OpenAIRE

Півняк, Геннадій Григорович; Бешта, Олександр Степанович; Фурса, Сергій Григорійович; Neuberger, Nikolaus; Nolle, N.

2010-01-01

The article describes design and simulation experience of permanent magnet synchronous motor (PMSM). The design goal is to develop PMSM of the least possible cost. For that purpose the standard induction motor stator was applied as a basic solution and permanent magnets were installed in rotor. Simulation results are presented, the dependence of efficiency and total loss on magnet material mass are obtained. The optimal value of permanent magnets is estimated for the given electric motor frame.

Magnetic forces between arrays of cylindrical permanent magnets

DEFF Research Database (Denmark)

Vokoun, D.; Tomassetti, G.; Beleggia, Marco

2011-01-01

procedures. Here, we introduce analytical expressions for calculating the attraction force between two arrays of cylindrical permanent magnets and compare the predictions with experimental data obtained from force measurements with NdFeB magnets. We show that the difference between predicted and measured...

Effect of gamma irradiation on the structural and magnetic properties of Co–Zn spinel ferrite nanoparticles

Energy Technology Data Exchange (ETDEWEB)

Raut, Anil V., E-mail: nano9993@gmail.com [Vivekanand Arts, Sardar Dalipsingh Commerce and Science College, Aurangabad 431004, (M.S.) India (India); Kurmude, D.V. [Milind College of Science, Aurangabad 431004, (M.S.) India (India); Shengule, D.R. [Vivekanand Arts, Sardar Dalipsingh Commerce and Science College, Aurangabad 431004, (M.S.) India (India); Jadhav, K.M. [Department of Physics, Dr. Babasaheb Ambedkar Marathwada University, Aurangabad 431004, (M.S.) India (India)

2015-03-15

Highlights: • Co–Zn ferrite nanoparticles were examined before and after γ-irradiation. • Single phase cubic spinel structure of Co–Zn was confirmed by XRD data. • The grain size was reported in the range of 52–62 nm after γ-irradiation. • Ms, Hc, n{sub B} were reported to be increased after gamma irradiation. - Abstract: In this work, the structural and magnetic properties of Co{sub 1−x}Zn{sub x}Fe{sub 2}O{sub 4} (0.0 ≤ x ≤ 1.0) ferrite nanoparticles were studied before and after gamma irradiation. The as-synthesized samples of Co–Zn ferrite nanoparticles prepared by sol–gel auto-combustion technique were analysed by XRD which suggested the single phase; cubic spinel structure of the material. Crystal defects produced in the spinel lattice were studied before and after Co{sup 60} γ-irradiation in a gamma cell with a dose rate of 0.1 Mrad/h in order to report the changes in structural and magnetic properties of the Co–Zn ferrite nanoparticles. The average crystallite size (t), lattice parameter (α) and other structural parameters of gamma-irradiated and un-irradiated Co{sub 1−x}Zn{sub x}Fe{sub 2}O{sub 4} spinel ferrite system was calculated from XRD data. The morphological characterizations were performed using scanning electron microscopy (SEM). The magnetic properties were measured using pulse field hysteresis loop tracer by applying magnetic field of 1000 Oe, and the analysis of data obtained revealed that the magnetic property such as saturation magnetization (Ms), coecivity (Hc), magneton number (n{sub B}) etc. magnetic parameters were increased after irradiation.

A rotary permanent magnet magnetic refrigerator based on AMR cycle

International Nuclear Information System (INIS)

Aprea, C.; Cardillo, G.; Greco, A.; Maiorino, A.; Masselli, C.

2016-01-01

Magnetic refrigeration is an emerging, environment-friendly technology based on a magnetic solid that acts as a refrigerant by magneto-caloric effect (MCE). The reference cycle for magnetic refrigeration is AMR (Active Magnetic Regenerative refrigeration). In order to demonstrate the potential of magnetic refrigeration to provide useful cooling in the near room temperature range, a novel Rotary Permanent Magnet Magnetic Refrigerator (RPMMR) is described in this paper. Gadolinium has been selected as magnetic refrigerant and demineralized water has been employed as regenerating fluid. The total mass of gadolinium (1.20 kg), shaped as packed bed spheres, is housed in 8 regenerators. A magnetic system, based on a double U configuration of permanent magnets, provides a magnetic flux density of 1.25 T with an air gap of 43 mm. A rotary vane pump forces the regenerating fluid through the regenerators. The operational principle of the magnetic refrigerator and initial experimental results are reported and analyzed.

Thermodynamic and kinetic characteristics of the austenite-to-ferrite transformation under high magnetic field in medium carbon steel

International Nuclear Information System (INIS)

Zhang Yudong; He Changshu; Zhao Xiang; Zuo Liang; Esling, Claude

2005-01-01

The thermodynamic and kinetic characteristics of austenite-to-ferrite phase transformation in medium carbon steel in the high magnetic fields were investigated. Results showed that the magnetic field could obviously change the γ/α+γ phase equilibrium-by increasing the amount of ferrite obtained during cooling-and greatly accelerate the transformation. Thus the microstructure obtained under fast cooling with high magnetic field was still ferritic and pearlitic, while that obtained without the magnetic field under the same cooling conditions was bainitic. Exploration in this area contributes both to enriching the new theory on electromagnetic processing of materials (EPM) and in establishing new techniques for materials processing

Electrical and magnetic properties of MgGa_(_2_-_x_)Fe_xO_4 ferrite

International Nuclear Information System (INIS)

Ribeiro, Vander Alkmin dos Santos

2005-01-01

The ceramics of the type ferrites are materials that present important characteristics of electrical conduction and magnetic properties, as much as material magnetic hard, how much of soft magnetic materials. The cubic ferrites of the spinel structure are oxides with chemical formula MFe_2O_4, where M is a divalent metallic ion. Due to characteristic of the spinel, diverse magnetic configurations are a gotten, depending on the occupation tax of the magnetic ion (in general iron) in each sublattice. The diluted ferrites possess general formula given for: MD_2_-_xFe_xO4, where M and D are diamagnetic ions, being D the ion of substitution doping and x is the concentration of ions of iron (0,002 ≤ x ≤ 0,350). The sample was prepared using ceramics techniques in reaction of solid state and later they were submitted to a magnetic characterization, electric and X-ray diffraction. The results of the magnetic characterization were gotten by a magnetometer of vibrant sample (VSM) EG&G-Princeton Applied Research, model 4500; the characterization for X-ray was used one X-ray diffractometer, model URD 65; of the Seifert & with. Electrical measurements DC were carried through with the use of a unit high-voltage measuring source - Keithley, model 237, where the voltage applied in the samples varied of 0-40 V, the high temperatures. Two types of contacts were used: the arrangement type 'sandwich', being the inferior electrode the proper door-sample, and the superior electrode with ring geometry and a silver was pasted on both sides of the samples to ensure good electrical contact. The magnetic measurements confirm its ferrite characteristics and in the electrical measurements, the electrical conductivity indicated behavior of a semiconductor the high temperatures and the process of electrical conduction thermally presented to be activated. (author)

Mössbauer and magnetization studies of nanosize chromium ferrite ...

African Journals Online (AJOL)

Nanosize chromium ferrite (CrF) powder samples were synthesized by citrate precursor route in the size range of 6 to 35 nm. The structural and magnetic behaviour of these samples were studied using X-ray diffraction (XRD), vibrating sample magnetometer (VSM) and Mössbauer spectroscopic techniques. Synthesized ...

Effect of saturating ferrite on the field in a prototype kicker magnet

International Nuclear Information System (INIS)

Barnes, M.J.; Wait, G.D.

1994-06-01

The field rise for kicker magnets is often specified between 1% and 99% of full strength. Three-gap thyratrons are frequently used as switches for kicker magnet systems. These thyratrons turn on in three stages: the collapse of voltage across one gap causes a displacement current to flow in the parasitic capacitance of off-state gap(s). The displacement current flows in the external circuit and can thus increase the effective rise-time of the field in the kicker magnet. One promising method of decreasing the effect of the displacement current involves the use of saturating ferrites. Another method for achieving the specified rise-time and 'flatness' for the kick strength is to utilize speed-up networks in the electrical circuit. Measurements have been carried out on a prototype kicker magnet with a speed-up network and various geometries of saturating ferrite. Measurements and PSpice calculations are presented. (author)

Investigation of Structural, Morphological, Magnetic Properties and Biomedical applications of Cu2+ Substituted Uncoated Cobalt Ferrite Nanoparticles

Directory of Open Access Journals (Sweden)

M. Margabandhu

Full Text Available ABSTRACT In the present work, Cu2+ substituted cobalt ferrite (Co1-xCuxFe2O4, x = 0, 0.3, 0.5, 0.7 and 1 magnetic nanopowders were synthesized via chemical co-precipitation method. The prepared powders were investigated by various characterization methods such as X-ray diffraction analysis (XRD, scanning electron microscope analysis (SEM, vibrating sample magnetometer analysis (VSM and fourier transform infrared spectroscopy analysis (FTIR. The XRD analysis reveals that the synthesized nanopowders possess single phase centred cubic spinel structure. The average crystallite size of the particles ranging from 27-49 nm was calculated by using Debye-scherrer formula. Magnetic properties of the synthesized magnetic nanoparticles are studied by using VSM. The VSM results shows the magnetic properties such as coercivity, magnetic retentivity decreases with increase in copper substitution whereas the saturation magnetization shows increment and decrement in accordance with Cu2+ substitution in cobalt ferrite nanoparticles. SEM analysis reveals the morphology of synthesized magnetic nanoparticles. FTIR spectra of Cu2+ substituted cobalt ferrite magnetic nanoparticles were recorded in the frequency range 4000-400cm-1. The spectrum shows the presence of water adsorption and metal oxygen bonds. The adhesion nature of Cu2+ substituted cobalt ferrite magnetic nanoparticles with bacteria in reviewed results indicates that the synthesized nanoparticles could be used in biotechnology and biomedical applications.

Investigation of structural and magnetic properties of Zr-Co doped nickel ferrite nanomaterials

Energy Technology Data Exchange (ETDEWEB)

Ali, Rajjab [Department of Chemistry, The Islamia University of Bahawalpur, Bahawalpur 63100 (Pakistan); Khan, Muhammad Azhar, E-mail: azhar.khan@iub.edu.pk [Department of Physics, The Islamia University of Bahawalpur, Bahawalpur 63100 (Pakistan); Manzoor, Alina [Department of Physics, The Islamia University of Bahawalpur, Bahawalpur 63100 (Pakistan); Department of Physics, Government College University, Faisalabad 38000 (Pakistan); Shahid, Muhammad [Department of Chemistry, The Islamia University of Bahawalpur, Bahawalpur 63100 (Pakistan); Haider, Sajjad [Chemical Engineering Department, College of Engineering, King Saud University, Riyadh 11421 (Saudi Arabia); Malik, Abdul Sattar [Department of Electrical Engineering, University College of Engineering and Technology, Bahauddin Zakariya University, Multan 60800 Pakistan (Pakistan); Sher, Muhammad [Department of Chemistry, University of Sargodha, Sargodha 40100 (Pakistan); Shakir, Imran [Sustainable Energy Technologies (SET) Center, College of Engineering, King Saud University, PO-BOX 800, Riyadh 11421 (Saudi Arabia); FarooqWarsi, Muhammad, E-mail: farooq.warsi@iub.edu.pk [Department of Chemistry, The Islamia University of Bahawalpur, Bahawalpur 63100 (Pakistan)

2017-05-01

Nano-sized Zr-Co doped nickel ferrites with nominal composition, NiZr{sub x}Co{sub x}Fe{sub 2-2x}O{sub 4} (x=0.0, 0.2, 0.4, 0.6, 0.8) were synthesized using the micro-emulsion route. The structural elucidation of the synthesized materials was carried out by X-ray diffraction (XRD) and Fourier transform infrared (FTIR) spectroscopy. The XRD analysis confirmed face centered cubic (FCC) structure of all compositions of NiZr{sub x}Co{sub x}Fe{sub 2-2x}O{sub 4} nanocrystallites. Crystallite size was calculated by Scherrer's formula found in the range 10–15 nm. The variation in lattice parameter as determined by XRD data agreed with size variation of host (Fe{sup 3+}) and guest (Zr{sup 4+} and Co{sup 2+}) cations. FTIR spectra of doped NiFe{sub 2}O{sub 4} exhibited the typical octahedral bands at 528.4 cm{sup −1} which is the characteristic feature of spinel structure of spinel ferrites. The characterized spinel NiZr{sub x}Co{sub x}Fe{sub 2-2x}O{sub 4} nano-ferrites were evaluated for their potential applications by magnetic hysteresis loops and dielectric measurements. The value of saturation magnetization (M{sub s}) decreased from 47.9 to 13.09 emu/g up to x=0.8 with ups and downs fluctuations in between x=0.0 to x=0.8. The high values of Ms of some compositions predicted the potential applications in high density perpendicular recording media and microwave devices. The frequency dependent behavior of permittivity (ε') is recorded and discussed with the help of hopping mechanism of both holes and electrons. The dielectric and magnetic data of NiZr{sub x}Co{sub x}Fe{sub 2-2x}O{sub 4} nano-ferrites suggested the potential applications of these ferrite nanoparticles in high frequency and magnetic data storage devices fabrication. - Graphical abstract: Zr-Co doped nickel nano-ferrites were prepared via micro-emulsion method. The crystallite size calculated by scherrer's formula lie in the range 10–15 nm. The saturation magnetization decreases from 47

Optimally segmented permanent magnet structures

DEFF Research Database (Denmark)

Insinga, Andrea Roberto; Bjørk, Rasmus; Smith, Anders

2016-01-01

We present an optimization approach which can be employed to calculate the globally optimal segmentation of a two-dimensional magnetic system into uniformly magnetized pieces. For each segment the algorithm calculates the optimal shape and the optimal direction of the remanent flux density vector......, with respect to a linear objective functional. We illustrate the approach with results for magnet design problems from different areas, such as a permanent magnet electric motor, a beam focusing quadrupole magnet for particle accelerators and a rotary device for magnetic refrigeration....

Influence of pH Adjustment Parameter for Sol-Gel Modification on Structural, Microstructure, and Magnetic Properties of Nanocrystalline Strontium Ferrite.

Science.gov (United States)

Azis, Raba'ah Syahidah; Sulaiman, Sakinah; Ibrahim, Idza Riati; Zakaria, Azmi; Hassan, Jumiah; Muda, Nor Nadhirah Che; Nazlan, Rodziah; Saiden, Norlaily M; Fen, Yap Wing; Mustaffa, Muhammad Syazwan; Matori, Khamirul Amin

2018-05-23

Synthesis of nanocrystalline strontium ferrite (SrFe 12 O 19 ) via sol-gel is sensitive to its modification parameters. Therefore, in this study, an attempt of regulating the pH as a sol-gel modification parameter during preparation of SrFe 12 O 19 nanoparticles sintered at a low sintering temperature of 900 °C has been presented. The relationship of varying pH (pH 0 to 8) on structural, microstructures, and magnetic behaviors of SrFe 12 O 19 nanoparticles were characterized by X-ray diffraction (XRD), field emission scanning microscope (FESEM), and vibrating sample magnetometer (VSM). Varying the pH of precursor exhibited a strong effect on the sintered density, crystal structure and magnetic properties of the SrFe 12 O 19 nanoparticles. As the pH is 0, the SrFe 12 O 19 produced relatively largest density, saturation magnetization, M s , and coercivity, H c , at a low sintering temperature of 900 °C. The grain size of SrFe 12 O 19 is obtained in the range of 73.6 to 133.3 nm. The porosity of the sample affected the density and the magnetic properties of the SrFe 12 O 19 ferrite. It is suggested that the low-temperature sintered SrFe 12 O 19 at pH 0 displayed M s of 44.19 emu/g and H c of 6403.6 Oe, possessing a significant potential for applying in low-temperature co-fired ceramic permanent magnet.

Open H-shaped permanent magnet structure for NMR imaging

International Nuclear Information System (INIS)

Nguyen, V.; Delamare, J.; Yonnet, J.P.

1996-01-01

Since NMR imaging at low field is now technically possible, permanent magnets can replace resistive coils or superconducting magnets. This paper reviews most of NMR structures that provide an uniform field using only permanent magnets. We propose a new open H-shaped structure that is simple to manufacture. This structure has been calculated thanks to an optimization program and a calculation method we presente here. It enables to determine with a good accuracy the field created by passive systems composed by permanent magnets and ferromagnetic materials. (author)

Permanent-magnet material applications in particle accelerators

International Nuclear Information System (INIS)

Kraus, R.H. Jr.

1992-01-01

The modern charged particle accelerator has found application in a wide range of scientific research, industrial, medical, and defense fields. Researchers began to use permanent-magnet materials in particle accelerators soon after the invention of the alternating gradient principle, which showed that magnetic field could be used to control the transverse envelope of charged particle beams. The history of permanent-magnet use in accelerator physics and technology is outlined, current design methods and material properties of concern for particle accelerator applications are reviewed

Modeling of ironless permanent magnet planar motor structures

NARCIS (Netherlands)

Boeij, de J.; Lomonova, E.A.; Vandenput, A.J.A.

2006-01-01

This paper describes an analytical model that includes end effects for ironless synchronous permanent-magnet planar actuators. Because of its flexibility, the model can be used to predict the performance of various permanent-magnet array and coil array topologies and commutation schemes. Moreover,

Moessbauer and magnetic susceptibility measurements on M-type hexagonal Ba - ferrite

International Nuclear Information System (INIS)

Lipka, J.; Gruskova, A.; Sitek, J.; Miglierini, M.; Groene, R.; Hucl, M.; Toth, I.; Orlicky, O.

1990-01-01

Samples of stoichiometric BaFe 12 O 19 and Co, Ti substituted barium ferrite were prepared by chemical wet method. Moessbauer spectroscopy, magnetic susceptibility measurements, X-ray diffraction, infrared spectroscopy were conducted to examine the mechanism of formation. The observed magnetic characteristics and electron scanning microscopy show that single domain coprecipitated powders were formed. (orig.)

Special-Purpose High-Torque Permanent-Magnet Motors

Science.gov (United States)

Doane, George B., III

1995-01-01

Permanent-magnet brushless motors that must provide high commanded torques and satisfy unusual heat-removal requirement are developed. Intended for use as thrust-vector-control actuators in large rocket engines. Techniques and concepts used to design improved motors for special terrestrial applications. Conceptual motor design calls for use of rotor containing latest high-energy-product rare-earth permanent magnets so that motor produces required torque while drawing smallest possible currents from power supply. Torque generated by electromagnetic interaction between stator and permanent magnets in rotor when associated electronic circuits applied appropriately temporally and spatially phased currents to stator windings. Phase relationships needed to produce commanded torque computed in response to torque command and to electronically sensed angular position of rotor relative to stator.

Magnetic losses versus sintering treatment in Mn-Zn ferrites

Energy Technology Data Exchange (ETDEWEB)

Beatrice, Cinzia, E-mail: c.beatrice@inrim.it [Istituto Nazionale di Ricerca Metrologica, Nanoscience and Materials Division, Torino (Italy); Tsakaloudi, Vasiliki [Laboratory of Inorganic Materials, CERTH, Thermi-Thessaloniki (Greece); Dobák, Samuel [Institute of Physics, P.J. Šafárik University, Košice (Slovakia); Zaspalis, Vassilios [Department of Chemical Engineering Aristotle University of Thessaloniki, Thessaloniki (Greece); Fiorillo, Fausto [Istituto Nazionale di Ricerca Metrologica, Nanoscience and Materials Division, Torino (Italy)

2017-05-01

Mn-Zn ferrites prepared by different sintering schedules at 1325 °C, 1340 °C, and 1360 °C, have been characterized from the structural, electrical, and magnetic viewpoint. Magnetic losses and complex permeability have been, in particular, measured and analyzed from quasi-static excitation up to 1 GHz. It is observed that lower sintering temperatures and shorter treatment times lead to more homogeneous grain structure and better soft magnetic response at all frequencies. It is shown, however, that, once the contribution by eddy currents is singled out, the energy losses tend to coincide beyond a few MHz in the differently treated samples. The interpretative approach consists in separating the contributions by the domain wall displacements and the magnetization rotations to complex permeability and losses as a function of frequency. This can be accomplished in a relatively simple way in the low induction region described by the Rayleigh law, where these quantities can be quantitatively related and the linear Landau-Lifshitz-Gilbert equation applies, account being taken of the distribution in amplitude and orientation of the local anisotropy fields. - Highlights: • DC-1 GHz magnetic losses and complex permeability of Mn-Zn ferrites are analyzed. • Contributions by domain wall displacements and rotations are separately obtained. • Energy losses caused by eddy currents and spin damping are separately identified. • Microstructure is shown to chiefly affect the domain wall processes. • Rotational permeability and loss are predicted through Landau-Lifshitz equation.

Performance Comparison of Permanent Magnet Linear Actuators of Different Mover Types

DEFF Research Database (Denmark)

Ritchie, Ewen; Hinov, K.; Yatchev, I.

2006-01-01

A comparative study of permanent magnet linear actuators with different location of the permanent magnet is reported. Three mover types are considered - soft magnetic mover, permanent magnet mover and hybrid mover. Force-stroke characteristics are obtained with the help of finite element models...

Optimization of permanent-magnet undulator magnets ordering using simulated annealing algorithm

International Nuclear Information System (INIS)

Chen Nian; He Duohui; Li Ge; Jia Qika; Zhang Pengfei; Xu Hongliang; Cai Genwang

2005-01-01

Pure permanent-magnet undulator consists of many magnets. The unavoidable remanence divergence of these magnets causes the undulator magnetic field error, which will affect the functional mode of the storage ring and the quality of the spontaneous emission spectrum. Optimizing permanent-magnet undulator magnets ordering using simulated annealing algorithm before installing undulator magnets, the first field integral can be reduced to 10 -6 T·m, the second integral to 10 -6 T·m 2 and the peak field error to less than 10 -4 . The optimized results are independent of the initial solution. This paper gives the optimizing process in detail and puts forward a method to quickly calculate the peak field error and field integral according to the magnet remanence. (authors)

Mössbauer and magnetic studies of nanocrystalline zinc ferrites synthesized by microwave combustion method

Energy Technology Data Exchange (ETDEWEB)

Mahmoud, Mohamed, E-mail: mamdouh-2000-2000@yahoo.com [Assiut University, Department of Physics (Egypt); Hassan, Azza Mohamed [Asuite University, Physics Department, Faculty of Sciences (Egypt); Ahmed, Mamdouh Abdel aal [Al Azhar University, Physics Department, Faculty of Science (Egypt); Zhu, Kaixin; Ganeshraja, Ayyakannu Sundaram; Wang, Junhu, E-mail: Wangjh@dicp.ac.cn [Chinese Academy Sciences, Mössbauer Effect Data Center & Laboratory of Catalysts and New Materials for Aerospace, Dalian Institute of Chemical Physics (China)

2016-12-15

Zinc ferrite nano-crystals were synthesized by a microwave assisted combustion route with varying the urea to metal nitrates (U/N) molar ratio The process takes only a few minutes to obtain Zinc ferrite powders. The Effect of U/N ratio on the obtained phases, particle size, magnetization and structural properties has been investigated. The specimens were characterized by XRD, Mössbauer and VSM techniques. The sample prepared with urea/metal nitrate ratio of 1/1 was a poorly crystalline phase with very small crystallite size. A second phase is also detected in the sample. The crystallite size increases while the second phase decrease with increasing the urea ratio. The saturation magnetization and coercivity of the as prepared nano-particles changed with the change of the U/N ratio. The powder with the highest U/N ratio showed the presence of an unusually high saturation magnetization of 16 emu/g at room temperature. The crystallinity of the as prepared powder was developed by annealing the samples at 700 {sup ∘}C and 900 {sup ∘}C. Both the saturation magnetization (Ms) and the remnant magnetization (Mr) were found to be highly dependent upon the annealing temperature. Mössbauer studies show magnetic ordering in the powder even at room temperature. The Mössbauer and the magnetic parameters of this fraction are different from the standard values for bulk zinc ferrite.

Microstructure and magnetic properties of M-type strontium hexagonal ferrites with Y-Co substitution

Energy Technology Data Exchange (ETDEWEB)

Liu, Chaocheng [School of Physics and Materials Science, Anhui University, Hefei 230601 (China); Liu, Xiansong, E-mail: xiansongliu@ahu.edu.cn [School of Physics and Materials Science, Anhui University, Hefei 230601 (China); Engineering Technology Research Center of Magnetic Materials, School of Physics & Materials Science, Anhui University, Hefei 230601 (China); Feng, Shuangjiu; Rehman, Khalid Mehmood Ur; Li, Mingling; Zhang, Cong; Li, Haohao; Meng, Xiangyu [School of Physics and Materials Science, Anhui University, Hefei 230601 (China)

2017-08-15

Highlights: • Y-Co substitution in strontium hexaferrites have been prepared and investigated systematically for the first time. • Lattice constants a and c for all the samples are very different with that of unsubstituted ferrites. • The M{sub s} and H{sub c} are very high, from which may provide an important significance of research and development of high performance products. - Abstract: According to the formula Sr{sub 0.95}Y{sub 0.05}Fe{sub 12−x}Co{sub x}O{sub 19} (x = 0.00, 0.08, 0.16, 0.24, 0.32, 0.40), the replacement of Y-Co in M-type strontium hexagonal ferrites have been successfully prepared by ceramic process for the first time. The phase compositions of magnetic powders were examined by X-ray diffraction. The results of XRD showed that the single phase was obtained in magnetic powders with the increase of Co content (x), and α-Fe{sub 2}O{sub 3} occurred when x > 0.24. The morphology of the magnets was investigated by scanning electron microscopy (SEM). The micro-morphology of the particles exhibited the uniform plane hexagonal structures of M-type ferrites with different Co content. Magnetic properties of the ferrite magnets were measured by a physical property measurement system-vibrating sample magnetometer (PPMS-VSM). The M{sub s} increases constantly with the increase of Co content. The H{sub c} first increases and then decreases with the increase of Co content, and the value of coercivity (H{sub c}) is up to 3774 Oe when x = 0.24.

Effect of PVP as a capping agent in single reaction synthesis of nanocomposite soft/hard ferrite nanoparticles

Energy Technology Data Exchange (ETDEWEB)

Ahmad, H.A. [Department of Physics, Faculty of Science, Universiti Putra Malaysia, UPM, 43400 Serdang, Selangor (Malaysia); Saiden, N.M., E-mail: nlaily@upm.edu.my [Department of Physics, Faculty of Science, Universiti Putra Malaysia, UPM, 43400 Serdang, Selangor (Malaysia); Saion, E.; Azis, R.S.; Mamat, M.S. [Department of Physics, Faculty of Science, Universiti Putra Malaysia, UPM, 43400 Serdang, Selangor (Malaysia); Hashim, M. [Advanced Material and Nanotechnology Laboratory, Institute of Advanced Technology, Universiti Putra Malaysia, UPM, 43400 Serdang, Selangor (Malaysia)

2017-04-15

Nanocomposite magnets consist of soft and hard ferrite phases are known as an exchange spring magnet when they are sufficiently spin exchange coupled. Hard and soft ferrites offer high value of coercivity, H{sub c} and saturation magnetization, M{sub s} respectively. In order to obtain a better permanent magnet, both soft and hard ferrite phases need to be “exchange coupled”. The nanoparticles were prepared by a simple one-pot technique of 80% soft phase and 20% hard phase. This technique involves a single reaction mixture of metal nitrates and aqueous solution of varied amounts of polyvinylpyrrolidone (PVP). The heat treatment applied was at 800 °C for 3 h. The synthesized composites were characterized by Transmission Electron Microscope (TEM), Fourier Transform Infra-red (FT-IR), Energy Dispersive X-Ray (EDX), X-ray diffraction (XRD) and Vibrating sample magnetometer (VSM). The coexistence of two phases, Ni{sub 0.5}Zn{sub 0.5}Fe{sub 2}O{sub 4} and SrFe{sub 12}O{sub 19} were observed by XRD patterns. It also verified by the EDX that no impurities detected. The magnetic properties of nanocomposite ferrites for 0.06 g/ml PVP gives a better properties of H{sub c} 932 G and M{sub s} 39.0 emu/g with average particle size obtained from FESEM was 49.2 nm. The concentration of PVP used gives effect on the magnetic properties of the samples. - Highlights: • Amount of PVP play important roles in controlling the particle size distribution and magnetic properties. • This is a novel technique to produce nanocomposite ferrites effectively. • This study contributes better understanding on magnetic properties in nanoparticle composite magnets.

Permanent magnet with MgB{sub 2} bulk superconductor

Energy Technology Data Exchange (ETDEWEB)

Yamamoto, Akiyasu, E-mail: yamamoto@appchem.t.u-tokyo.ac.jp [The University of Tokyo, 7-3-1 Hongo, Bunkyo, Tokyo 113-8656 (Japan); JST-PRESTO, 4-1-8 Honcho, Kawaguchi, Saitama 332-0012 (Japan); Ishihara, Atsushi; Tomita, Masaru [Railway Technical Research Institute, 2-8-38 Hikari, Kokubunji, Tokyo 185-8540 (Japan); Kishio, Kohji [The University of Tokyo, 7-3-1 Hongo, Bunkyo, Tokyo 113-8656 (Japan)

2014-07-21

Superconductors with persistent zero-resistance currents serve as permanent magnets for high-field applications requiring a strong and stable magnetic field, such as magnetic resonance imaging. The recent global helium shortage has quickened research into high-temperature superconductors (HTSs)—materials that can be used without conventional liquid-helium cooling to 4.2 K. Herein, we demonstrate that 40-K-class metallic HTS magnesium diboride (MgB{sub 2}) makes an excellent permanent bulk magnet, maintaining 3 T at 20 K for 1 week with an extremely high stability (<0.1 ppm/h). The magnetic field trapped in this magnet is uniformly distributed, as for single-crystalline neodymium-iron-boron. Magnetic hysteresis loop of the MgB{sub 2} permanent bulk magnet was determined. Because MgB{sub 2} is a simple-binary-line compound that does not contain rare-earth metals, polycrystalline bulk material can be industrially fabricated at low cost and with high yield to serve as strong magnets that are compatible with conventional compact cryocoolers, making MgB{sub 2} bulks promising for the next generation of Tesla-class permanent-magnet applications.

Magnet management in electric machines

Science.gov (United States)

Reddy, Patel Bhageerath; El-Refaie, Ayman Mohamed Fawzi; Huh, Kum Kang

2017-03-21

A magnet management method of controlling a ferrite-type permanent magnet electrical machine includes receiving and/or estimating the temperature permanent magnets; determining if that temperature is below a predetermined temperature; and if so, then: selectively heating the magnets in order to prevent demagnetization and/or derating the machine. A similar method provides for controlling magnetization level by analyzing flux or magnetization level. Controllers that employ various methods are disclosed. The present invention has been described in terms of specific embodiment(s), and it is recognized that equivalents, alternatives, and modifications, aside from those expressly stated, are possible and within the scope of the appending claims.

Defect induced modification of structural, topographical and magnetic properties of zinc ferrite thin films by swift heavy ion irradiation

Energy Technology Data Exchange (ETDEWEB)

Raghavan, Lisha [Department of Physics, Cochin University of Science and Technology, Cochin 682022 (India); Inter University Accelerator Center, New Delhi 110067 (India); Joy, P.A. [National Chemical Laboratory, Pune (India); Vijaykumar, B. Varma; Ramanujan, R.V. [School of Materials Science and Engineering, Nanyang Technological University (Singapore); Anantharaman, M.R., E-mail: mraiyer@gmail.com [Department of Physics, Cochin University of Science and Technology, Cochin 682022 (India)

2017-04-01

Highlights: • Zinc ferrite films exhibited room temperature ferrimagnetic property. • On ion irradiation amorphisation of films were observed. • The surface morphology undergoes changes with ion irradiation. • The saturation magnetisation decreases on ion irradiation. - Abstract: Swift heavy ion irradiation provides unique ways to modify physical and chemical properties of materials. In ferrites, the magnetic properties can change significantly as a result of swift heavy ion irradiation. Zinc ferrite is an antiferromagnet with a Neel temperature of 10 K and exhibits anomalous magnetic properties in the nano regime. Ion irradiation can cause amorphisation of zinc ferrite thin films; thus the role of crystallinity on magnetic properties can be examined. The influence of surface topography in these thin films can also be studied. Zinc ferrite thin films, of thickness 320 nm, prepared by RF sputtering were irradiated with 100 MeV Ag ions. Structural characterization showed amorphisation and subsequent reduction in particle size. The change in magnetic properties due to irradiation was correlated with structural and topographical effects of ion irradiation. A rough estimation of ion track radius is done from the magnetic studies.

A Partially Magnetized Ferrite LTCC-Based SIW Phase Shifter for Phased Array Applications

KAUST Repository

Ghaffar, Farhan A.

2015-06-01

The theory and design of a half-mode substrate-integrated waveguide ferrite low-temperature cofired ceramic-based phase shifter are presented in this paper. Unlike typical ferrite-based designs, the biasing is done through embedded windings in a multi-layer substrate that not only obviates the requirement of bulky electromagnets, but also prevents loss of bias fields at the air-to-ferrite interface. The phase shifter is operated in the partially magnetized state of ferrite substrate. Through the combined effect of embedded windings, half-mode waveguide operation, and partially magnetized state, the required bias fields have been reduced by 90% as compared with conventional ferrite-based designs employing electromagnets. A complete analytical model, backed up by electromagnetic simulations and measured results from a prototype, is presented in this paper. The fabricated prototype demonstrates a phase shift of 83.2° at a center frequency of 13.1 GHz and a figure of merit of 83.2°/dB. As a proof-of-concept, the proposed phase shifter design is monolithically integrated with a two-element antenna array to demonstrate a measured beam steering of 30°. The phase shifter design is highly efficient in terms of required bias fields, and it has a small form factor and can be easily integrated with other electronic components and systems. © 1965-2012 IEEE.

Cryogenic Permanent Magnet Undulators

International Nuclear Information System (INIS)

Chavanne, J.; Lebec, G.; Penel, C.; Revol, F.; Kitegi, C.

2010-01-01

For an in-vacuum undulator operated at small gaps the permanent magnet material needs to be highly resistant to possible electron beam exposure. At room temperature, one generally uses Sm 2 Co 17 or high coercivity NdFeB magnets at the expense of a limited field performance. In a cryogenic permanent magnet undulator (CPMU), at a temperature of around 150 K, any NdFeB grade reveals a coercivity large enough to be radiation resistant. In particular, very high remanence NdFeB material can be used to build undulators with enhanced field and X-ray brilliance at high photon energy provided that the pre-baking of the undulator above 100 deg. C can be eliminated. The ESRF has developed a full scale 2 m long CPMU with a period of 18 mm. This prototype has been in operation on the ID6 test beamline since January 2008. A significant effort was put into the characterization of NdFeB material at low temperature, the development of dedicated magnetic measurement systems and cooling methods. The measured heat budget with beam is found to be larger than expected without compromising the smooth operation of the device. Leading on from this first experience, new CPMUs are currently being considered for the upgrade of the ESRF.

Structural and magnetic Ni-Zn ferrite synthesized by combustion reaction and sintered in a conventional oven

International Nuclear Information System (INIS)

Vieira, D.A.; Diniz, V.C.S.; Costa, A.C.F.M.; Kiminami, R.H.G.A.; Cornejo, D.R.

2011-01-01

The Ni-Zn ferrite due to their electrical and magnetic properties allows use in various technological applications. These properties can be controlled through appropriate choice of chemical composition, structural characteristics and morphology of the powders used and the techniques used for sintering. Thus, this study aims to evaluate the sintering in a conventional oven at a temperature of 1200 deg C/2h samples of Ni-Zn ferrite synthesized by microwave energy. The samples were characterized by density measurement, XRD, SEM and magnetic measurements. The results indicate the phase formation of Ni-Zn ferrite crystalline phase with crystallite size of 80 nm. The sample was heterogeneous microstructure with grain size of about 1 μm high intergranular porosity. The sample showed the saturation magnetization of 7.57 emu/g, coercive field and remanent magnetization close to zero, thus indicating a behavior characteristic of superparamagnetic materials. (author)

Design strategy for a tunable antenna on a partially magnetized ferrite LTCC substrate

KAUST Repository

Ghaffar, Farhan A.; Shamim, Atif; Bray, Joey R.

2014-01-01

Typical microwave simulators cannot accurately predict the behavior of an antenna on a partially magnetized substrate as they assume the substrate to be in fully saturate state. In this work, a new simulation strategy aided by theoretical analysis, is presented to model a tunable patch antenna on a partially magnetized ferrite substrate through a combination of magnetostatic and microwave simulators. An antenna prototype is fabricated in Ferrite LTCC medium to verify the partially magnetized state simulations. The measured results are in close agreement with the simulations, contrary to the case where the substrate is assumed to be in saturation. The prototype designed for 13 GHz exhibits a tuning range of 10 % making it highly suitable for tunable and reconfigurable wireless applications.

Design strategy for a tunable antenna on a partially magnetized ferrite LTCC substrate

KAUST Repository

Ghaffar, Farhan A.

2014-07-01

Typical microwave simulators cannot accurately predict the behavior of an antenna on a partially magnetized substrate as they assume the substrate to be in fully saturate state. In this work, a new simulation strategy aided by theoretical analysis, is presented to model a tunable patch antenna on a partially magnetized ferrite substrate through a combination of magnetostatic and microwave simulators. An antenna prototype is fabricated in Ferrite LTCC medium to verify the partially magnetized state simulations. The measured results are in close agreement with the simulations, contrary to the case where the substrate is assumed to be in saturation. The prototype designed for 13 GHz exhibits a tuning range of 10 % making it highly suitable for tunable and reconfigurable wireless applications.

Magnetic field shimming of a permanent magnet using a combination of pieces of permanent magnets and a single-channel shim coil for skeletal age assessment of children.

Science.gov (United States)

Terada, Y; Kono, S; Ishizawa, K; Inamura, S; Uchiumi, T; Tamada, D; Kose, K

2013-05-01

We adopted a combination of pieces of permanent magnets and a single-channel (SC) shim coil to shim the magnetic field in a magnetic resonance imaging system dedicated for skeletal age assessment of children. The target magnet was a 0.3-T open and compact permanent magnet tailored to the hand imaging of young children. The homogeneity of the magnetic field was first improved by shimming using pieces of permanent magnets. The residual local inhomogeneity was then compensated for by shimming using the SC shim coil. The effectiveness of the shimming was measured by imaging the left hands of human subjects and evaluating the image quality. The magnetic resonance images for the child subject clearly visualized anatomical structures of all bones necessary for skeletal age assessment, demonstrating the usefulness of combined shimming. Copyright © 2013 Elsevier Inc. All rights reserved.

Permanent Magnetic System Design for the Wall-Climbing Robot

Directory of Open Access Journals (Sweden)

W. Shen

2006-01-01

Full Text Available This paper presents the design and analysis of the permanent magnetic system for a wall-climbing robot with permanent magnetic tracks. Based on the behaviour of gecko lizards, the architecture of the robot was designed and built, including the structure of the adhesion mechanism, the mechanical architecture and the anti-toppling mechanism. The permanent magnetic adhesion mechanism and the tracked locomotion mechanism were employed in this kind of wall-climbing robot. Through static and dynamic force analysis of the robot under different situations, design requirements for the adhesion mechanism were derived. Two different types of structures were put forward for the permanent magnetic units and are further discussed in this paper. These two types of structures are also analysed in detail. In addition, a finite-element method was used to verify the results of magnetic units. Finally, two wall-climbing robots, equipped with different magnetic systems described previously, are explained and their applications are discussed in this paper.

A chiral-based magnetic memory device without a permanent magnet.

Science.gov (United States)

Ben Dor, Oren; Yochelis, Shira; Mathew, Shinto P; Naaman, Ron; Paltiel, Yossi

2013-01-01

Several technologies are currently in use for computer memory devices. However, there is a need for a universal memory device that has high density, high speed and low power requirements. To this end, various types of magnetic-based technologies with a permanent magnet have been proposed. Recent charge-transfer studies indicate that chiral molecules act as an efficient spin filter. Here we utilize this effect to achieve a proof of concept for a new type of chiral-based magnetic-based Si-compatible universal memory device without a permanent magnet. More specifically, we use spin-selective charge transfer through a self-assembled monolayer of polyalanine to magnetize a Ni layer. This magnitude of magnetization corresponds to applying an external magnetic field of 0.4 T to the Ni layer. The readout is achieved using low currents. The presented technology has the potential to overcome the limitations of other magnetic-based memory technologies to allow fabricating inexpensive, high-density universal memory-on-chip devices.

Discussions on performance of two types of permanent multipole magnets

International Nuclear Information System (INIS)

Xu Jianming; Xu Qing; Yin Zhaosheng

1987-01-01

The field distributions of MMD type and MW type multipole permanent magnets are calculated by means of programme POISCR and the results are summarized and discussed in this paper. The resutls show that, considering the nonlinearity of the real demagnetization curve of permanent magnet material, the field distributions of both types of permanent magnets with the same aperature are about the same but the field strength of MW type magnet with soft iron shield is higher than that of MMD type magnet

Nonstoichiometric Zn Ferrite and ZnFe2O4/Fe2O3 Composite Spheres: Preparation, Magnetic Properties, and Chromium Removal

Science.gov (United States)

Hang, Chun-Liang; Yang, Li-Xia; Sun, Chang-Mei; Liang, Ying

2018-03-01

Monodisperse and porous nonstoichiometric Zn ferrite can be prepared by a solvothermal method. Such non-Zn ferrite was used to be the precursor for synthesis of ZnFe2O4/Fe2O3 composite via calcination at 600°C for 3 h in air. X-ray powder diffractometer (XRD) and Energy Dispersive Spectrometer (EDS) proved the nonstoichiometry of Zn ferrite synthesized by solvothermal method and the formation of ZnFe2O4/Fe2O3 composite via calcination. TEM image showed that non-Zn ferrite spheres with wormlike nanopore structure were made of primary nanocrystals. BET surface area of non-Zn ferrite was much higher than that of ZnFe2O4/Fe2O3 composite. Saturation magnetization of non-Zn ferrites was significantly higher than that of ZnFe2O4/Fe2O3 composites. Calcination of non-Zn ferrite resulted in the formation of large amount of non-magnetic Fe2O3,which caused a low magnetization of composite. Because of higher BET surface area and higher saturation magnetization, non-Zn ferrite presented better Cr6+ adsorption property than ZnFe2O4/Fe2O3 composites.

Investigation of local fields in different barium ferrite sublattices by means of nuclear magnetic resonance

International Nuclear Information System (INIS)

Utrecht, R.; Hankiewicz, J.

1995-01-01

The local fields on 57 Fe nuclei in ferrite (BaFe 12 O 19 ) polycrystals have been investigated by means of spin echo amplitudes measurements at 4.2 and 77 K. The magnetic moment orientation and local field intensity have been determined for five different ferrite sublattices

Characterizing permanent magnet blocks with Helmholtz coils

Science.gov (United States)

Carnegie, D. W.; Timpf, J.

1992-08-01

Most of the insertion devices to be installed at the Advanced Photon Source will utilize permanent magnets in their magnetic structures. The quality of the spectral output is sensitive to the errors in the field of the device which are related to variations in the magnetic properties of the individual blocks. The Advanced Photon Source will have a measurement facility to map the field in the completed insertion devices and equipment to test and modify the magnetic strength of the individual magnet blocks. One component of the facility, the Helmholtz coil permanent magnet block measurement system, has been assembled and tested. This system measures the total magnetic moment vector of a block with a precision better than 0.01% and a directional resolution of about 0.05°. The design and performance of the system will be presented.

The cycloid Permanent Magnetic Gear

DEFF Research Database (Denmark)

Rasmussen, Peter Omand; Andersen, Torben Ole; Jørgensen, Frank T.

2008-01-01

This paper presents a new permanent-magnet gear based on the cycloid gearing principle. which normally is characterized by an extreme torque density and a very high gearing ratio. An initial design of the proposed magnetic gear was designed, analyzed, and optimized with an analytical model...... regarding torque density. The results were promising as compared to other high-performance magnetic-gear designs. A test model was constructed to verify the analytical model....

Analysis of Hall Probe Precise Positioning with Cylindrical Permanent Magnet

International Nuclear Information System (INIS)

Belicev, P.; Vorozhtsov, A.S.; Vorozhtsov, S.B.

2007-01-01

Precise positioning of a Hall probe for cyclotron magnetic field mapping, using cylindrical permanent magnets, was analyzed. The necessary permanent magnet parameters in order to achieve ±20 μm position precision, were determined. (author)

Structure and magnetic properties of iron-based soft magnetic composite with Ni-Cu-Zn ferrite-silicone insulation coating

Science.gov (United States)

Li, Wangchang; Wang, Wei; Lv, Junjun; Ying, Yao; Yu, Jing; Zheng, Jingwu; Qiao, Liang; Che, Shenglei

2018-06-01

This paper investigates the structure and magnetic properties of Ni-Cu-Zn ferrite-silicone coated iron-based soft magnetic composites (SMCs). Scanning electron microscopy coupled with a energy-dispersive spectroscopy (EDS) analysis revealed that the Ni-Cu-Zn ferrite and silicone resin were uniformly coated on the surface of iron powders. By controlling the composition of the coating layer, low total core loss of 97.7 mW/cm3 (eddy current loss of 48 mW/cm3, hysteresis loss of 49.7 mW/cm3, measured at 100 kHz and 0.02 T) and relatively high effective permeability of 72.5 (measured at 100 kHz) were achieved. In addition, the as-prepared SMCs displayed higher electrical resistivity, good magnetic characteristics over a wide range of frequencies (20-200 kHz) and ideal the D-C bias properties (more than 75% at H = 50 Oe). Furthermore, higher elastic modulus and hardness of SMCs, which means that the coating layer has good mechanical properties and is not easily damaged during the pressing process, were obtained in this paper. The results of this work indicate that the Ni-Cu-Zn ferrite-silicone coated SMCs have desirable properties which would make them suitable for application in the fields of the electric-magnetic switching devices, such as inductance coils, transformer cores, synchronous electric motors and resonant inductors.

Magnetically nonlinear dynamic model of synchronous motor with permanent magnets

International Nuclear Information System (INIS)

Hadziselimovic, Miralem; Stumberger, Gorazd; Stumberger, Bojan; Zagradisnik, Ivan

2007-01-01

This paper deals with a magnetically nonlinear two-axis dynamic model of a permanent magnet synchronous motor (PMSM). The geometrical and material properties of iron core and permanent magnets, the effects of winding distribution, saturation, cross-saturation and slotting effects are, for the first time, simultaneously accounted for in a single two-axis dynamic model of a three-phase PMSM. They are accounted for by current- and position-dependent characteristics of flux linkages. These characteristics can be determined either experimentally or by the finite element (FE) computations. The results obtained by the proposed dynamic model show a very good agreement with the measured ones and those obtained by the FE computation

Design and simulation of permanent magnet synchronous motor control system

Science.gov (United States)

Li, Li; Liu, Yongqiu

2018-06-01

In recent years, with the development of power electronics, microelectronics, new motor control theory and rare earth permanent magnet materials, permanent magnet synchronous motors have been rapidly applied. Permanent magnet synchronous motors have the advantages of small size, low loss and high efficiency. Today, energy conservation and environmental protection are increasingly valued. It is very necessary to study them. Permanent magnet synchronous motor control system has a wide range of application prospects in the fields of electric vehicles, ships and other transportation. Using the simulation function of MATLAB/SIMULINK, a modular design structure was used to simulate the whole system model of speed loop adjustment, current PI modulation, SVPWM (Space Vector Pulse Width Module) wave generation and double closed loop. The results show that this control method has good robustness, and this method can improve the design efficiency and shorten the system design time. In this article, the analysis of the control principle of modern permanent magnet synchronous motor and the various processes of MATLAB simulation application will be analyzed in detail. The basic theory, basic method and application technology of the permanent magnet synchronous motor control system are systematically introduced.

Repulsion analysis of permanent magnets for the Hoop energy storage system

International Nuclear Information System (INIS)

O, B. H.; Cho, S. B.; Kim, D. I.

1996-01-01

The repulsion force of permanent magnets is studied in order to analyze the instability problem of the rotational motion of a hoop levitated by permanent magnets in the Hoop Energy Storage System (HESS). The hoop of permanent magnets is levitated to remove the mechanical complexities caused by the rotational axis. It is important to maintain stable rotational motion at any speed for the efficiency as well as the safety of the system. To set up the equations of motion, the force of levitation and the source of perturbation are represented in terms of real parameters of the permanent magnets. The instability conditions and various geometric effects of the permanent magnets are analyzed. (author)

Stabilization of magnet assemblies of permanent magnet sodium flowmeters used in fast breeder reactors

Energy Technology Data Exchange (ETDEWEB)

Rajan, K.K., E-mail: kkrajan@igcar.gov.in; Vijayakumar, G.

2014-08-15

Highlights: • Stabilization procedure for ALNICO-5 permanent magnet material is evolved. • Effect of time and temperature on ALNICO-5 assembly is determined. • Suitability of ALNICO-5 flowmeters at high temperatures is established. • Temperature coefficient of flux density is determined. - Abstract: Permanent magnet flow meters (PMFMs) are used to measure the sodium flow in sodium cooled Fast Breeder Reactor Circuits. Prototype fast breeder reactor (PFBR) which is under construction at Kalpakkam is a 500 MWe, sodium cooled, pool type reactor. Sodium flow measurement in various loops of the reactor is of prime importance from operational and safety point of view. To measure the flow of electrically conducting liquid sodium, in primary and secondary circuit pipe lines of PFBR, permanent magnet flow meters are used. PMFM is a non-invasive device, which works on the principle of generation of motional EMF by magnetic forces exerted on the charges in a moving conductor. Flowmeters of different pipe sizes ranging from 10 mm to 200 mm pipe diameter are required for PFBR. Long term performance of the flowmeters mainly depends on stability of permanent magnets used in flowmeters to generate constant magnetic field in stainless steel (SS) pipes. This paper describes the effects of time and temperature on permanent magnet assemblies made of ALNICO-V used in PFBR flowmeters. The stabilization methodology for ALNICO-V permanent magnet assemblies is evolved and established. Loss of magnetic field strength with respect to time and temperatures is determined by experiments and found negligible.

Impacts of yttrium substitution on FMR line-width and magnetic properties of nickel spinel ferrites

Energy Technology Data Exchange (ETDEWEB)

Ishaque, M., E-mail: ishaqdgk1@gmail.com [Department of Physics, Bahauddin Zakariya University, Multan 60800 (Pakistan); Khan, Muhammad Azhar, E-mail: azhar.khan@iub.edu.pk [Department of Physics, The Islamia University of Bahawalpur, Bahawalpur 63100 (Pakistan); Ali, Irshad; Khan, Hasan M. [Department of Physics, Bahauddin Zakariya University, Multan 60800 (Pakistan); Iqbal, M. Asif [Department of Physics, Bahauddin Zakariya University, Multan 60800 (Pakistan); College of E & ME, National University of Science and Technology, Islamabad (Pakistan); Islam, M.U. [Department of Physics, Bahauddin Zakariya University, Multan 60800 (Pakistan); Warsi, Muhammad Farooq [Department of Chemistry, The Islamia University of Bahawalpur, Bahawalpur 63100 (Pakistan)

2015-05-15

The influence of yttrium (Y) substitution on ferromagnetic resonance (FMR), initial permeability, and magnetic properties of NiFe{sub 2}O{sub 4} ferrites were investigated. It was observed that the FMR line-width decreases with yttrium contents for the substitution level 0≤×≤0.06. Beyond this, the FMR line-width increases with yttrium contents. The nominal composition NiY{sub 0.12}Fe{sub 1.88}O{sub 4} exhibited the smallest FMR line-width ~282 Oe. A significant change in FMR position of nickel–yttrium (Ni–Y) ferrites was observed and it found to exist between 4150 and 4600 Oe. The saturation magnetization was observed to decrease with the increase of yttrium contents and this was referred to the redistribution of cations on octahedral. The coercivity increased from 15 Oe to 59 Oe by increasing the yttrium concentration. The initial permeability decreased from 110 to 35 at 1 MHz by the incorporation of yttrium and this was attributed to the smaller grains which may obstruct the domain wall movement and impede the domain wall motion. The magnetic loss factors of substituted samples exhibit decreasing behavior in the frequency range 1 kHz to 10 MHz. The smaller FMR line-width and reduced magnetic loss factor of the investigated samples suggest the possible use of these materials in high frequency applications. - Highlights: • Influence of Y{sup 3+} substitution on the properties of nickel ferrites is investigated. • Very small FMR line-width (282 Oe) is exhibited by these substituted ferrites. • Fourfold increase in coercivity was observed for NiY{sub 0.24}Fe{sub 1.76}O{sub 4} ferrites.

Secondary emission yield at low-primary energies of magnetic materials for anti-multipactor applications

CERN Document Server

Aguilera, L; Olano, L; Casas, A; Morales, P; Vázquez, M; Galán, L; Caspers, F; Costa-Pinto, P; Taborelli, M; Raboso, D

2014-01-01

Secondary electron emission processes under electron bombardment are central to many effects at surfaces and interfaces, and to many in vacuum high power RF electronic devices where multipactor can be very intense [1,2]. Ferrite materials are usually used in microwave components used in space telecommunication systems, as circulators, phase-shifters, switches, and isolators. The physics of the multipactor phenomenon existing in microwave devices based on ferrite materials is an important issue and it is urgent to be researched [3]. One difficulty in the analysis of the multipactor effect in RF components containing ferrite lies on the fact that this material is an anysotropic magnetic medium controlled by an applied permanent magnetic field, which is used to magnetize the ferrite material. SEY and other properties (structure, magnetic behaviour,...) of soft-magnetic materials were studied in this work. MnZn soft ferrites magnets are suitable in the situation of frequency < 3MHz, low loss and high μi. Comp...

A tubular flux-switching permanent magnet machine

Science.gov (United States)

Wang, J.; Wang, W.; Clark, R.; Atallah, K.; Howe, D.

2008-04-01

The paper describes a novel tubular, three-phase permanent magnet brushless machine, which combines salient features from both switched reluctance and permanent magnet machine technologies. It has no end windings and zero net radial force and offers a high power density and peak force capability, as well as the potential for low manufacturing cost. It is, therefore, eminently suitable for a variety of applications, ranging from free-piston energy converters to active vehicle suspensions.

Magnetic hyperthermia heating of cobalt ferrite nanoparticles prepared by low temperature ferrous sulfate based method

Directory of Open Access Journals (Sweden)

Tejabhiram Yadavalli

2016-05-01

Full Text Available A facile low temperature co-precipitation method for the synthesis of crystalline cobalt ferrite nanostructures using ferrous sulfate salt as the precursor has been discussed. The prepared samples were compared with nanoparticles prepared by conventional co-precipitation and hydrothermal methods using ferric nitrate as the precursor. X-ray diffraction studies confirmed the formation of cubic spinel cobalt ferrites when dried at 110 °C as opposed to conventional methods which required higher temperatures/pressure for the formation of the same. Field emission scanning electron microscope studies of these powders revealed the formation of nearly spherical nanostructures in the size range of 20-30 nm which were comparable to those prepared by conventional methods. Magnetic measurements confirmed the ferromagnetic nature of the cobalt ferrites with low magnetic remanance. Further magnetic hyperthermia studies of nanostructures prepared by low temperature method showed a rise in temperature to 50 °C in 600 s.

Enhancement of magnetic coupling between permanent magnets and bulk superconductors through iron embedding

International Nuclear Information System (INIS)

Seki, H.; Kurabayashi, H.; Suzuki, A.; Ikeda, M.; Akiyama, S.; Murakami, M.

2009-01-01

Magnetic torque can be transferred without contact through the coupling of permanent magnets (PM) and bulk superconductors (BSC). For this purpose, permanent magnets should have multiple pole configuration like NSNS. The magnitude of the transferable torque depends on the field strength and the gap between PM and BSC. It was found that the torque decays quickly with the gap. In order to enhance the strength of transferable magnetic torque, we prepared bulk Y-Ba-Cu-O superconductors for which Fe bars are embedded. Holes about 1 mm in diameter were mechanically drilled into bulk Y-Ba-Cu-O, and Fe bars about 0.9 mm in diameter were inserted followed by impregnation of Bi-Pb-Sn alloys with low melting points. The composite of Y-Ba-Cu-O and Fe bars attract magnetic fields generated from permanent magnet before cooling, and thereby magnetic coupling will be improved. We have found that the magnetic torque force can be greatly enhanced through iron embedding.

A novel structure of permanent-magnet-biased radial hybrid magnetic bearing

International Nuclear Information System (INIS)

Sun Jinji; Fang Jiancheng

2011-01-01

The paper proposes a novel structure for a permanent-magnet-biased radial hybrid magnetic bearing. Based on the air gap between the rotor and stator of traditional radial hybrid magnetic bearings, a subsidiary air gap is first constructed between the permanent magnets and the inner magnetic parts. Radial magnetic bearing makes X and Y magnetic fields independent of each other with separate stator poles, and the subsidiary air gap makes control flux to a close loop. As a result, magnetic field coupling of the X and Y channels is decreased significantly by the radial hybrid magnetic bearing and makes it easier to design control systems. Then an external rotor structure is designed into the radial hybrid magnetic bearing. The working principle of the radial hybrid magnetic bearing and its mathematical model is discussed. Finally, a non-linear magnetic network method is proposed to analyze the radial hybrid magnetic bearing. Simulation results indicate that magnetic fields in the two channels of the proposed radial hybrid magnetic bearing decouple well from each other.

A novel structure of permanent-magnet-biased radial hybrid magnetic bearing

Energy Technology Data Exchange (ETDEWEB)

Sun Jinji, E-mail: sunjinji@aspe.buaa.edu.c [Key Laboratory of Fundamental Science for National Defense, Novel Inertial Instrument and Navigation System Technology, School of Instrument Science and Opto-electronics Engineering, Beijing University of Aeronautics and Astronautics, 100191 (China); Fang Jiancheng [Key Laboratory of Fundamental Science for National Defense, Novel Inertial Instrument and Navigation System Technology, School of Instrument Science and Opto-electronics Engineering, Beijing University of Aeronautics and Astronautics, 100191 (China)

2011-01-15

The paper proposes a novel structure for a permanent-magnet-biased radial hybrid magnetic bearing. Based on the air gap between the rotor and stator of traditional radial hybrid magnetic bearings, a subsidiary air gap is first constructed between the permanent magnets and the inner magnetic parts. Radial magnetic bearing makes X and Y magnetic fields independent of each other with separate stator poles, and the subsidiary air gap makes control flux to a close loop. As a result, magnetic field coupling of the X and Y channels is decreased significantly by the radial hybrid magnetic bearing and makes it easier to design control systems. Then an external rotor structure is designed into the radial hybrid magnetic bearing. The working principle of the radial hybrid magnetic bearing and its mathematical model is discussed. Finally, a non-linear magnetic network method is proposed to analyze the radial hybrid magnetic bearing. Simulation results indicate that magnetic fields in the two channels of the proposed radial hybrid magnetic bearing decouple well from each other.

Tailoring the magnetic properties and magnetorheological behavior of spinel nanocrystalline cobalt ferrite by varying annealing temperature.

Science.gov (United States)

Sedlacik, Michal; Pavlinek, Vladimir; Peer, Petra; Filip, Petr

2014-05-14

Magnetic nanoparticles of spinel nanocrystalline cobalt ferrite were synthesized via the sol-gel method and subsequent annealing. The influence of the annealing temperature on the structure, magnetic properties, and magnetorheological effect was investigated. The finite crystallite size of the particles, determined by X-ray diffraction and the particle size observed via transmission electron microscopy, increased with the annealing temperature. The magnetic properties observed via a vibrating sample magnetometer showed that an increase in the annealing temperature leads to the increase in the magnetization saturation and, in contrast, a decrease in the coercivity. The effect of annealing on the magnetic properties of ferrite particles has been explained by the recrystallization process at high temperatures. This resulted in grain size growth and a decrease in an imposed stress relating to defects in the crystal lattice structure of the nanoparticles. The magnetorheological characteristics of suspensions of ferrite particles in silicone oil were measured using a rotational rheometer equipped with a magnetic field generator in both steady shear and small-strain oscillatory regimes. The magnetorheological performance expressed as a relative increase in the magnetoviscosity appeared to be significantly higher for suspensions of particles annealed at 1000 °C.

Asynchronous slip-ring motor synchronized with permanent magnets

Directory of Open Access Journals (Sweden)

Glinka Tadeusz

2017-03-01

Full Text Available The electric LSPMSM motor presented in the paper differs from standard induction motor by rotor design. The insulated start-up winding is located in slots along the rotor circumference. The winding ends are connected to the slip-rings. The rotor core contains permanent magnets. The electromechanical characteristics for synchronous operation were calculated, as were the start-up characteristics for operation with a short-circuited rotor winding. Two model motors were used for the calculations, the V-shaped Permanent Magnet (VPM – Fig. 3, and the Linear Permanent Magnet (IPM – Fig. 4, both rated at 14.5 kW. The advantages of the investigated motor are demonstrated in the conclusions.

Novel ocean energy permanent magnet linear generator buoy

Energy Technology Data Exchange (ETDEWEB)

Rhinefrank, K.; Agamloh, E.B.; Jouanne, A. von; Wallace, A.K.; Prudell, J.; Kimble, K.; Aills, J.; Schmidt, E.; Schacher, A. [School of Electrical Engineering and Computer Science, Oregon State University, Corvallis, OR 97331-3211 (United States); Chan, P.; Sweeny, B. [Department of Mechanical Engineering, Oregon State University, Corvallis, OR 97331-3211 (United States)

2006-07-15

This paper describes the research, design, construction and prototype testing process of a novel ocean energy direct drive permanent magnet linear generator buoy. The buoy employs the vertical component of the motion of ocean waves to power a linear generator. The generator consists of a permanent magnet field system (mounted on the central translator shaft) and an armature, in which the power is generated (mounted on the buoy). The translator shaft is anchored to the sea floor, and the buoy/floater moves armature coils relative to the permanent magnet translator to induce voltages. The electrical and mechanical structures of the buoy generator are provided, along with performance characteristics, including voltage, current and developed power. (author)

High-field permanent-magnet structures

International Nuclear Information System (INIS)

Leupoid, H.A.

1989-01-01

This patent describes a permanent magnet structure. It comprises an azimuthally circumscribed section of a hollow hemispherical magnetic flux source, the magnetic orientation in the section with respect to the polar axis being substantially equal to twice the polar angle, a superconducting planar sheet abutting one flat face of the section along a longitudinal meridian, and at least one other planar sheet of selected material abutting another flat face of the section and perpendicular to the first-mentioned sheet

Improving soft magnetic properties of Mn-Zn ferrite by rare earth ions doping

Science.gov (United States)

Zhong, X. C.; Guo, X. J.; Zou, S. Y.; Yu, H. Y.; Liu, Z. W.; Zhang, Y. F.; Wang, K. X.

2018-04-01

Mn-Zn ferrites doped with different Sm2O3, Gd2O3, Ce2O3 or Y2O3 were prepared by traditional ceramic technology using industrial pre-sintered powders. A small amount of Sm2O3, Gd2O3, Ce2O3 or Y2O3 can significantly improve the microstructure and magnetic properties. The single spinel phase structure can be maintained with the doping amount up to 0.07 wt.%. A refined grain structure and uniform grain size distribution can be obtained by doping. For all rare earth oxides, a small amount of doping can significantly increase the permeability and reduce the coercivity and magnetic core loss. The optimized doping amount for Sm2O3 or Gd2O3 is 0.01 wt.%, while for Ce2O3 or Y2O3 is 0.03 wt.%. A further increase of the doping content will lead to reduced soft magnetic properties. The ferrite sample with 0.01 wt.% Sm2O3 exhibits the good magnetic properties with permeability, loss, and coercivity of 2586, 316 W/kg, and 24A/m, respectively, at 200 mT and 100 kHz. The present results indicate that rare earth doping can be suggested to be one of the effective ways to improve the performance of soft ferrites.

Improving soft magnetic properties of Mn-Zn ferrite by rare earth ions doping

Directory of Open Access Journals (Sweden)

X. C. Zhong

2018-04-01

Full Text Available Mn-Zn ferrites doped with different Sm2O3, Gd2O3, Ce2O3 or Y2O3 were prepared by traditional ceramic technology using industrial pre-sintered powders. A small amount of Sm2O3, Gd2O3, Ce2O3 or Y2O3 can significantly improve the microstructure and magnetic properties. The single spinel phase structure can be maintained with the doping amount up to 0.07 wt.%. A refined grain structure and uniform grain size distribution can be obtained by doping. For all rare earth oxides, a small amount of doping can significantly increase the permeability and reduce the coercivity and magnetic core loss. The optimized doping amount for Sm2O3 or Gd2O3 is 0.01 wt.%, while for Ce2O3 or Y2O3 is 0.03 wt.%. A further increase of the doping content will lead to reduced soft magnetic properties. The ferrite sample with 0.01 wt.% Sm2O3 exhibits the good magnetic properties with permeability, loss, and coercivity of 2586, 316 W/kg, and 24A/m, respectively, at 200 mT and 100 kHz. The present results indicate that rare earth doping can be suggested to be one of the effective ways to improve the performance of soft ferrites.

Roles of coercivity and remanent flux density of permanent magnet in interior permanent magnet synchronous motor (IPMSM) performance for electric vehicle applications

Science.gov (United States)

Won, Hoyun; Hong, Yang-Ki; Lee, Woncheol; Choi, Minyeong

2018-05-01

We used four rotor topologies of an interior permanent magnet synchronous motor (IPMSM) to investigate the effects of remanent flux density (Br) and coercivity (Hc) of permanent magnet on motor performance. Commercial strontium hexaferrite (SrFe12O19: energy product, (BH)max, of 4.62 MGOe) and Nd-Fe-B ((BH)max of 38.2 MGOe) magnets were used for the rotor designs. The same machine specifications and magnet volume keep constant, while the Hc and Br vary to calculate torque and energy efficiency with the finite-element analysis. A combination of high Hc and low Br more effectively increased maximum torque of IPMSM when the hexaferrite magnet was used. For Nd-Fe-B magnet, the same combination did not affect maximum torque, but increased energy efficiency at high speed. Therefore, the Hc value of a permanent magnet is more effective than the Br in producing high maximum torque for SrM-magnet based IPMSM and high energy efficiency at high speed for Nd-Fe-B magnet based IPMSM.

Effect of the repulsive force in the HTSC-permanent magnet hybrid bearing system

International Nuclear Information System (INIS)

Ohashi, S.; Kobayashi, S.

2009-01-01

Magnetic levitation using the pinning force of the YBaCuO high-T c bulk superconductor (HTSC) materials has an advantage to achieve stable levitation without control. To increase levitation force, the HTSC-permanent magnet hybrid magnetic bearing system is introduced. A circular shaped three phase Nd-Fe-B permanent magnet is installed on the rotor, and HTSC bulk superconductor is set on the stator. The additional permanent magnet is installed under the HTSC. Repulsive force of the permanent magnet is used for levitation, and pinning force between the HTSC and permanent magnet is used for guidance force of the bearing. In this system, relationship between permanent magnet and the HTSC is important. When repulsive force of the permanent magnet is large, pinning force of superconductor is used to keep the rotor position. As a result, stability for the lateral direction is decreased with hybrid system. For levitation force, effect of the hybrid system is not observed with column HTSC. Compared with the ring HTSC results, the following thing is considered. Because there is no space that flux of one permanent magnet acts on the other one with the column HTSC configuration, interaction between two permanent magnets becomes small.

Theoretical validation for changing magnetic fields of systems of permanent magnets of drum separators

Science.gov (United States)

Lozovaya, S. Y.; Lozovoy, N. M.; Okunev, A. N.

2018-03-01

This article is devoted to the theoretical validation of the change in magnetic fields created by the permanent magnet systems of the drum separators. In the article, using the example of a magnetic separator for enrichment of highly magnetic ores, the method of analytical calculation of the magnetic fields of systems of permanent magnets based on the Biot-Savart-Laplace law, the equivalent solenoid method, and the superposition principle of fields is considered.

System and method for preventing stator permanent magnet demagnetization during vacuum pressure impregnation

Science.gov (United States)

Raminosoa, Tsarafidy; Alexander, James Pellegrino; EL-Refaie, Ayman Mohamed Fawzi

2017-06-06

A permanent magnet electrical machine includes a stator having conductive windings wound thereon and one or more permanent magnets embedded in the stator. A magnetic keeper element is positioned on the stator so as to form a magnetic flux path with the permanent magnets, with the magnetic keeper element closing the magnetic flux path of the permanent magnets by providing a low reluctance flux path to magnetic flux generated by the permanent magnets. A vacuum pressure impregnation (VPI) process is performed on the stator to increase a thermal conductivity of the windings, with the VPI process including a curing step that is performed at a selected temperature. The magnetic keeper element sets an operating point of the permanent magnets to an internal flux density level above a demagnetization threshold associated with the selected temperature at which the curing step is performed.

Forces Between a Permanent Magnet and a Soft Magnetic Plate

DEFF Research Database (Denmark)

Beleggia, Marco; Vokoun, David; De Graef, Marc

2012-01-01

Forces between a hard/permanent magnet of arbitrary shape and an ideally soft magnetic plate in close proximity are derived analytically from the image method applied to magnetostatics. We found that the contact force, defined as the force required to detach the hard magnet from the plate, coinci...

Variable-field permanent-magnet quadrupole for the SSC

International Nuclear Information System (INIS)

Barlow, D.B.; Kraus, R.H. Jr.; Martinez, R.P.; Meyer, R.E.

1994-01-01

A set of compact variable-field permanent-magnet quadrupoles have been designed, fabricated, and tested for use in the SSC linac matching section. The quadrupoles have 24 mm-diameter apertures and 40 mm-long poles. The hybrid (permanent-magnet and iron) design, uses a fixed core of magnet material (NdFeB) and iron (C-1006) surrounded by a rotating ring of the same magnet material and iron. The quadrupole gradient-length product can be smoothly varied from a minimum of 0.7 T up to a maximum of 4.3 T by a 90 degree rotation of the outer ring of iron and magnet material

Variable-field permanent magnet quadrupole for the SSC

International Nuclear Information System (INIS)

Barlow, D.B.; Kraus, R.H. Jr.; Martinez, R.P.; Meyer, R.E.

1993-01-01

A set of compact variable-field permanent-magnet quadrupoles have been designed, fabricated, and tested for use In the SSC linac matching section. The quadrupoles have 24 mm-diameter apertures and 40 mm-long poles. The hybrid (permanent-magnet and iron) design, uses a fixed core of magnet material (NdFeB) and iron (C-1006) surrounded by a rotating ring of the same magnet material and iron. The quadrupole gradient-length product can be smoothly varied from a minimum of 0.7 T up to a maximum, of 4.3 T by a 90 degrees rotation of the outer ring of iron and magnet material

Highly stable and finely tuned magnetic fields generated by permanent magnet assemblies.

Science.gov (United States)

Danieli, E; Perlo, J; Blümich, B; Casanova, F

2013-05-03

Permanent magnetic materials are the only magnetic source that can be used to generate magnetic fields without power consumption or maintenance. Such stand-alone magnets are very attractive for many scientific and engineering areas, but they suffer from poor temporal field stability, which arises from the strong sensitivity of the magnetic materials and mechanical support to temperature variation. In this work, we describe a highly efficient method useful to cancel the temperature coefficient of permanent magnet assemblies in a passive and accurate way. It is based on the combination of at least two units made of magnetic materials with different temperature coefficients arranged in such a way that the ratio of the fields generated by each unit matches the ratio of their effective temperature coefficients defined by both the magnetic and mechanical contributions. Although typically available magnetic materials have negative temperature coefficients, the cancellation is achieved by aligning the fields generated by each unit in the opposite direction. We demonstrate the performance of this approach by stabilizing the field generated by a dipolar Halbach magnet, recently proposed to achieve high field homogeneity. Both the field drift and the homogeneity are monitored via nuclear magnetic resonance spectroscopy experiments. The results demonstrate the compatibility of the thermal compensation approach with existing strategies useful to fine-tune the spatial dependence of the field generated by permanent magnet arrays.

Rotatable Small Permanent Magnet Array for Ultra-Low Field Nuclear Magnetic Resonance Instrumentation: A Concept Study.

Science.gov (United States)

Vogel, Michael W; Giorni, Andrea; Vegh, Viktor; Pellicer-Guridi, Ruben; Reutens, David C

2016-01-01

We studied the feasibility of generating the variable magnetic fields required for ultra-low field nuclear magnetic resonance relaxometry with dynamically adjustable permanent magnets. Our motivation was to substitute traditional electromagnets by distributed permanent magnets, increasing system portability. The finite element method (COMSOL®) was employed for the numerical study of a small permanent magnet array to calculate achievable magnetic field strength, homogeneity, switching time and magnetic forces. A manually operated prototype was simulated and constructed to validate the numerical approach and to verify the generated magnetic field. A concentric small permanent magnet array can be used to generate strong sample pre-polarisation and variable measurement fields for ultra-low field relaxometry via simple prescribed magnet rotations. Using the array, it is possible to achieve a pre-polarisation field strength above 100 mT and variable measurement fields ranging from 20-50 μT with 200 ppm absolute field homogeneity within a field-of-view of 5 x 5 x 5 cubic centimetres. A dynamic small permanent magnet array can generate multiple highly homogeneous magnetic fields required in ultra-low field nuclear magnetic resonance (NMR) and magnetic resonance imaging (MRI) instruments. This design can significantly reduce the volume and energy requirements of traditional systems based on electromagnets, improving portability considerably.

Structural and Magnetic Properties of Type-M Barium Ferrite - Thermoplastic Natural Rubber Nano composites

International Nuclear Information System (INIS)

Nurhidayaty Mokhtar

2012-01-01

Structural and magnetic properties of type-M barium ferrite (BaFe 12 O 19 ) nanoparticles (∼ 20 nm) embedded in non-magnetic thermoplastic natural rubber (TPNR) matrices were investigated. The TPNR matrices were prepared from high density polyethylene (HDPE) and natural rubber (NR) in the weight ratios of 80:20 and 60:40, respectively, with 10 wt % of NR in the form of liquid natural rubber (LNR) which act as a comparabilities. BaFe 12 O 19 - filled nano composites with 2 - 12 wt % BaFe 12 O 19 ferrite were prepared using a melt- blending technique. Magnetic hysteresis was measured using a vibrating sample magnetometer (VSM) in a maximum field of 10 kOe at room temperature (25 degree Celsius). The saturation magnetisation (MS), remanence (MR) and coercivity (Hc) were derived from the hysteresis loops. The results show that the structural and magnetic properties of nano composites depend on both the ferrite content and the composition of the natural rubber or plastic in the nano composites. All the nano composites exhibit an exchange bias-like phenomenon resulting from the exchange coupling of spins at the interface between the core ferrimagnetic region and the disordered surface region of the nanoparticles. (author)

Method for forming permanent magnets with different polarities for use in microelectromechanical devices

Science.gov (United States)

Roesler, Alexander W [Tijeras, NM; Christenson, Todd R [Albuquerque, NM

2007-04-24

Methods are provided for forming a plurality of permanent magnets with two different north-south magnetic pole alignments for use in microelectromechanical (MEM) devices. These methods are based on initially magnetizing the permanent magnets all in the same direction, and then utilizing a combination of heating and a magnetic field to switch the polarity of a portion of the permanent magnets while not switching the remaining permanent magnets. The permanent magnets, in some instances, can all have the same rare-earth composition (e.g. NdFeB) or can be formed of two different rare-earth materials (e.g. NdFeB and SmCo). The methods can be used to form a plurality of permanent magnets side-by-side on or within a substrate with an alternating polarity, or to form a two-dimensional array of permanent magnets in which the polarity of every other row of the array is alternated.

Efficient IEC permanent-magnet motor (3 kW) - Final report; Effizienter IEC Permanent-Magnet-Motor (3 kW) - Schlussbericht

Energy Technology Data Exchange (ETDEWEB)

Lindegger, M. [Circle Motor AG, Guemligen (Switzerland); Biner, H. P.; Evequoz, B. [Haute Ecole valaisanne, Sion (Switzerland); Salathe, D. [Hochschule Luzern, Technik und Architektur, Horw (Switzerland)

2008-04-15

Efficient permanent-magnet motors achieve in the area up to 100 kW a higher efficiency than induction machines (standard motors). A simple and fast energy saving option is the exchange of inefficient standard motors. The objective of this work is to install a 3 kW permanent-magnet motor in a standard IEC housing and the optimization of the design for high efficiency. Another objective is the development and the realization of an efficient variable speed control. The efficiency of the motor and the inverter with the control system must be demonstrated by tests. These tasks have been split between Circle Motor AG and the universities of applied sciences of Valais and Lucerne. Considering high-efficiency and low manufacturing cost, a brushless DC solution was adopted. This resulted in an optimum design of the motor and the control system realized with a three-phase rectifier, a buck converter with variable DC voltage, and a three-phase inverter feeding full positive and negative current to two of the legs simultaneously. The maximum measured efficiency is about 96.5% for the inverter and 92% for the motor. With the advantage of the variable speed operation, the efficiency of the realized 3 kW permanent magnet motor together with the control system is always higher than the efficiency of a measured class EFF1 induction motor, even with a direct connection to the grid. The permanent-magnet motor is also about 10 kg lighter. The cost calculation shows that the permanent-magnet motor can be competitive with the induction motor when speed control is desired. This is also the domain with the largest potential for energy savings from variable speed pumps, compressors, fans. (author)

Ferrite-guided cyclotron-resonance maser

International Nuclear Information System (INIS)

Jerby, Eli; Kesar, A.; Aharony, A.; Breitmeier, G.

2002-01-01

The concept of a cyclotron-resonance maser (CRM) with a ferrite loading incorporated in its waveguide is proposed. The CRM interaction occurs between the rotating electron beam and the em wave propagating along a longitudinally magnetized ferrite medium. The ferrite anisotropic permeability resembles the CRM susceptibility in many aspects, and particularly in their similar response to the axial magnetic field (the ferrite susceptibility can be regarded as a passive analog of the active CRM interaction). The ferrite loading slows down the phase velocity of the em wave and thus the axial (Weibel) mechanism of the CRM interaction dominates. The ferrite loading enables also a mechanism of spectral tunability for CRM's. The ferrite loading is proposed, therefore, as a useful ingredient for high-power CRM devices. A linear model of the combined ferrite-guided CRM interaction reveals its useful features. Future schemes may also incorporate ferrite sections functioning as isolators, gyrators, or phase shifters within the CRM device itself for selective suppression of backward waves and spurious oscillations, and for gain and efficiency enhancement

Analysis of a spherical permanent magnet actuator

International Nuclear Information System (INIS)

Wang, J.; Jewell, G.W.; Howe, D.

1997-01-01

This paper describes a new form of actuator with a spherical permanent magnet rotor and a simple winding arrangement, which is capable of a high specific torque by utilizing a rare-earth permanent magnet. The magnetic-field distribution is established using an analytical technique formulated in spherical coordinates, and the results are validated by finite element analysis. The analytical field solution allows the prediction of the actuator torque and back emf in closed forms. In turn, these facilitate the characterization of the actuator and provide a firm basis for design optimization, system dynamic modeling, and closed-loop control law development. copyright 1997 American Institute of Physics

Perspectives for high-performance permanent magnets: applications, coercivity, and new materials

Science.gov (United States)

Hirosawa, Satoshi; Nishino, Masamichi; Miyashita, Seiji

2017-03-01

High-performance permanent magnets are indispensable in the production of high-efficiency motors and generators and ultimately for sustaining the green earth. The central issue of modern permanent magnetism is to realize high coercivity near and above room temperature on marginally hard magnetic materials without relying upon the critical elements such as heavy rare earths by means of nanostructure engineering. Recent investigations based on advanced nanostructure analysis and large-scale first principles calculations have led to significant paradigm shifts in the understandings of coercivity mechanism in Nd-Fe-B permanent magnets, which includes the discovery of the ferromagnetism of the thin (2 nm) intergranular phase surrounding the Nd2Fe14B grains, the occurrence of negative (in-plane) magnetocrystalline anisotropy of Nd ions and some Fe atoms at the interface which degrades coercivity, and visualization of the stochastic behaviors of magnetization in the magnetization reversal process at high temperatures. A major change may occur also in the motor topologies, which is currently overwhelmed by the magnetic flux weakening interior permanent magnet motor type, to other types with variable flux permanent magnet type in some applications to open up a niche for new permanent magnet materials. Keynote talk at 8th International Workshop on Advanced Materials Science and Nanotechnology (IWAMSN2016), 8-12 November 2016, Ha Long City, Vietnam.

Automatic design of permanent magnet coupling

International Nuclear Information System (INIS)

Yonnet, J.-P.; Pandele, P.; Coutel, C.; Wurtz, F.

1998-01-01

Up to now, two main methods have been used to design permanent magnet couplings : finite element calculation, and analytical expressions of the forces between the magnets. The two methods use the same starting point, the permanent magnet coupling dimensions. The calculated parameters are the forces and the torques. The optimization of the couplings shape is generally done by using different curves describing torque variations as a function of the different geometrical parameters. We have developed a very new approach solving the reverse problem. Choosing the value of the torque, the airgap and an optimization criterium, the new method automatically calculates the size of the magnets and the ideal number of poles. It is based on a software, PASCOSMA, using an analytical model of the coupling which can be eventually corrected by a finite element method like FLUX2D. The coupling optimization is automatically made, keeping the parameters between predefined values. For a given application, it is very easy to obtain the best design, for example with the minimum magnet volume. (orig.)

Design and characterization of permanent magnetic solenoids for REGAE

International Nuclear Information System (INIS)

Hachmann, M.; Flöttmann, K.; Gehrke, T.; Mayet, F.

2016-01-01

REGAE is a small electron linear accelerator at DESY. In order to focus short and low charged electron bunches down to a few μm permanent magnetic solenoids were designed, assembled and field measurements were done. Due to a shortage of space close to the operation area an in-vacuum solution has been chosen. Furthermore a two-ring design made of wedges has been preferred in terms of beam dynamic issues. To keep the field quality of a piecewise built magnet still high a sorting algorithm for the wedge arrangement including a simple magnetic field model has been developed and used for the construction of the magnets. The magnetic field of these solenoids has been measured with high precision and compared to simulations. - Highlights: • presenting a two-ring radially magnetized permanent magnetic solenoid design. • development of a analytical field description and field quality factor. • development of a sorting algorithm for permanent magnetic pieces to form a magnet. • performing a high-precision field measurement of a high gradient field.

Didactic Considerations on Magnetic Circuits Excited by Permanent Magnets

Science.gov (United States)

Barmada, S.; Rizzo, R.; Sani, L.

2009-01-01

In this paper, the authors focus their attention on the way magnetic circuits and permanent magnets are usually treated in most textbooks and electrical engineering courses. This paper demonstrates how this important topic is too often presented simplistically. This simplistic treatment does not allow the students to develop a complete…

Exact analytical modeling of magnetic vector potential in surface inset permanent magnet DC machines considering magnet segmentation

Science.gov (United States)

Jabbari, Ali

2018-01-01

Surface inset permanent magnet DC machine can be used as an alternative in automation systems due to their high efficiency and robustness. Magnet segmentation is a common technique in order to mitigate pulsating torque components in permanent magnet machines. An accurate computation of air-gap magnetic field distribution is necessary in order to calculate machine performance. An exact analytical method for magnetic vector potential calculation in surface inset permanent magnet machines considering magnet segmentation has been proposed in this paper. The analytical method is based on the resolution of Laplace and Poisson equations as well as Maxwell equation in polar coordinate by using sub-domain method. One of the main contributions of the paper is to derive an expression for the magnetic vector potential in the segmented PM region by using hyperbolic functions. The developed method is applied on the performance computation of two prototype surface inset magnet segmented motors with open circuit and on load conditions. The results of these models are validated through FEM method.

Motor Integrated Permanent Magnet Gear with a Wide Torque-Speed Range

DEFF Research Database (Denmark)

Rasmussen, Peter Omand; Matzen, Torben N.; Jahns, T. M.

2009-01-01

This paper present a new motor integrated permanent magnet gear with a wide torque-speed range. In the paper a 35 kW permanent magnet motor with a base speed of 4000 rpm and a top speed of 14000 rpm is integrated into a permanent magnetic gear with a gearing ratio of 8.67. The design process...

Permanent magnet quadrupoles for the CLIC Drive Beam decelerator

CERN Document Server

Shepherd, Ben; Collomb, Norbert

2012-01-01

STFC in collaboration with CERN has developed a new type of adjustable permanent magnet based quadrupole for the CLIC Drive Beam Decelerator. It uses vertical movement of the permanent magnets to achieve an integrated gradient range of 3.6-14.6T, which will allow it to be used for the first 60% of the decelerator line. Construction of a prototype of this magnet has begun; following this, it will be measured magnetically at CERN and Daresbury Laboratory.

Structural and magnetic properties of Ni-Zn and Ni-Zn-Co ferrites

Energy Technology Data Exchange (ETDEWEB)

Knyazev, A.V., E-mail: knyazevav@gmail.com [N.I. Lobachevsky State University of Nizhni Novgorod, Gagarin Prospekt 23/2, 603950 Nizhni Novgorod (Russian Federation); Zakharchuk, I.; Lähderanta, E. [Lappeenranta University of Technology, P.O. Box 20, FI-53851 Lappeenranta (Finland); Baidakov, K.V.; Knyazeva, S.S. [N.I. Lobachevsky State University of Nizhni Novgorod, Gagarin Prospekt 23/2, 603950 Nizhni Novgorod (Russian Federation); Ladenkov, I.V. [Joint-stock Company “Research and Production Company “Salut”, Nizhni Novgorod (Russian Federation)

2017-08-01

Highlights: • Ni-Zn and Ni-Zn-Co ferrite powders were prepared by the solid-state reaction at 1073 K. • The room temperature saturation magnetizations are 59.7 emu/g for Ni{sub 0.5}Zn{sub 0.5}Fe{sub 2}O{sub 4} and 57.1 emu/g for Ni{sub 0.5}Zn{sub 0.3}Co{sub 0.2}Fe{sub 2}O{sub 4}. • The coercivity of the samples is found to be much larger than that of bulk ferrites and increases with Co introduction. • The temperature dependences of magnetization exhibit large spin frustration and spin-glass-like behavior. - Abstract: Ni-Zn and Ni-Zn-Co ferrite powders with nominal compositions Ni{sub 0.5}Zn{sub 0.5}Fe{sub 2}O{sub 4} and Ni{sub 0.5}Zn{sub 0.3}Co{sub 0.2}Fe{sub 2}O{sub 4} were prepared by the solid-state reaction synthesis with periodic regrinding during the calcination at 1073 K. The structure of Ni{sub 0.5}Zn{sub 0.5}Fe{sub 2}O{sub 4} and Ni{sub 0.5}Zn{sub 0.3}Co{sub 0.2}Fe{sub 2}O{sub 4} was refined assuming space group F d-3m. Scanning electron microscopy revealed the average sizes of the crystalline ferrite particles are 130–630 nm for Ni{sub 0.5}Zn{sub 0.5}Fe{sub 2}O{sub 4} and 140–350 nm for Ni{sub 0.5}Zn{sub 0.3}Co{sub 0.2}Fe{sub 2}O{sub 4}. The room temperature saturation magnetizations are 59.7 emu/g for Ni{sub 0.5}Zn{sub 0.5}Fe{sub 2}O{sub 4} and 57.1 emu/g for Ni{sub 0.5}Zn{sub 0.3}Co{sub 0.2}Fe{sub 2}O{sub 4}. The coercivity of the samples is found to be much larger than that of bulk ferrites and increases with Co introduction. The Curie temperature tends to increase upon Zn substitution by Co, as well. The temperature dependences of magnetization measured using zero-field cooled and field cooled protocols exhibit large spin frustration and spin-glass-like behavior.

Permanent magnet-based MRI

Science.gov (United States)

Cole, David Mitchell

1997-10-01

The principal goal of this project is to design and build a low-cost, imaging quality permanent magnet, together with the requisite shim, gradient, and radiofrequency coils, and to integrate the magnet with an existing imaging station. There are commercial products presently available that are very similar to this imager, but information about these products is proprietary. We present here all of the details concerning the design and the manufacturing process for constructing the permanent magnet, and include suggestions for improvement. Specifically, the prototype has a mass of about 150 kilograms and is therefore portable. It's C-type geometry allows maximum access to the imaging region, which is an oblate sphere about 0.5 inches in diameter centered in a 4.7 inch air gap between two seven-inch diameter polefaces. It is hoped that this imaging magnet will serve as the prototype for a series of larger versions that will be clinically useful and affordable to physicians in developing nations. To this end, scientists in the United States and Mexico have begun to collaborate with the intention to create an MRI institute in Mexico that will train new students in this discipline, and fabricate improved imagers. The prototype resulting from this work will seed the creation of this institute, and is intended to entice students into the study of MRI by enabling hands-on interaction with an otherwise prohibitively expensive instrument.

Nanocomposite permanent magnetic materials Nd-Fe-B type: The influence of nanocomposite on magnetic properties

Directory of Open Access Journals (Sweden)

Talijan Nadežda M.

2005-01-01

Full Text Available The influence on the magnetic properties of nanocristalline ribbons and powders has character of microstructure, between others – the grain size volume of hard and soft magnetic phases and their distribution. Magnetic properties of ribbons and powders depend mainly on their chemical composition and parameters of their heat treatment [1]. Technology of magnets from nanocristalline ribbon consists of the following process: preparing the Nd-Fe- B alloy, preparing the ribbon, powdering of the ribbon, heat treatment of the powder and finally preparing the magnets. Nanocomposite permanent magnet materials based on Nd-Fe- B alloy with Nd low content are a new type of permanent magnetic material. The microstructure of this nanocomposite permanent magnet is composed of a mixture of magnetically soft and hard phases which provide so called exchange coupling effect.

Magnetic behavior of nickel ferrite nanoparticles prepared by co-precipitation route

International Nuclear Information System (INIS)

Maaz, K.; Mashiatullah, A.; Javed, T.; Ali, G.; Karim, S.

2008-01-01

Magnetic nanoparticles of nickel ferrite (NiFe/sub 2/O/sub 4/) have been synthesized by co-precipitation route using stable ferric and nickel salts with sodium hydroxide as the precipitating agent and oleic acid as the surfactant. X-ray Diffraction (XRD) and Transmission Electron Microscope (TEM) analyses confirmed the formation of single phase nickel ferrite nanoparticles in the range 8-28 nm. The size of the particles was observed to be increasing linearly with increasing annealing temperature of the sample. Typical blocking effects were observed below -225 K for all the prepared samples. The superparamagnetic blocking temperature was found to be continuously increasing with increasing particle sizes that has been attributed to the increased effective anisotropy of the nanoparticles. The saturation moment of all the samples was found much below the bulk value of nickel ferrite that has been attributed to the disordered surface spins of these nanoparticles. (author)

New microstructural features occurring during transformation from austenite to ferrite under the kinetic influence of magnetic field in a medium carbon steel

International Nuclear Information System (INIS)

Zhang Yudong; He Changshu; Zhao Xiang; Zuo Liang; Esling, Claude; He, Jicheng

2004-01-01

The effects of magnetic field on nucleation barrier of the phase transformation from austenite to ferrite at different cooling rates in 42CrMo steel have been investigated. The microstructures of ferrite and pearlite aligned along the magnetic field direction (parallel to the hot-rolling direction) are obtained at a cooling rate of 10 deg. C/min, resulting from the kinetic effects of the applied magnetic field during cooling and the microstructural influences of an inhomogeneous deformation occurring during the previous hot rolling. In this case, the formation of ferrite grains at higher temperatures is attributed mainly to the preferential nucleation at austenite boundaries. However, a fairly uniform microstructure of randomly distributed ferrite and pearlite is formed at a high cooling rate of 46 deg. C/min in the magnetic field of 14 T, as a result of both intergranular and intragranular nucleation at relatively low temperatures. Probing into this issue is helpful to gain a better understanding of kinetic influences of magnetic field on the phase transformation from austenite to ferrite

Structural, magnetic and electrical properties of nickel doped Mn-Zn spinel ferrite synthesized by sol-gel method

Energy Technology Data Exchange (ETDEWEB)

Jalaiah, K., E-mail: kjalu4u@gmail.com [Department of Physics, Andhra University, Visakhapatnam 530003 (India); Vijaya Babu, K. [Advanced Analytical Laboratory, Andhra University, Visakhapatnam 530003 (India)

2017-02-01

Manganese ferrites (MnFe{sub 2}O{sub 4}) have been of great interest for their remarkable and soft-magnetic properties (low coercivity, moderate saturation magnetization) accompanied by good chemical stability and mechanical hardness. X-ray diffraction analysis confirmed the presence of single phase cubic spinel ferrite with space group Fm3m for all prepared samples. Structural parameters such as lattice constant, crystallite size were calculated from the studies of X-ray diffraction. The morphological analysis of all the compounds is studied using scanning electron microscope. The magnetic properties were measured using electron spin resonance (ESR) and vibrating sample magnetometer (VSM). The results obtained showed the formation of manganese ferrites with an average particle size are in good agreement with previous results and displayed good magnetic properties. The dielectric and impedance properties are studied over a frequency range 20 Hz–1 MHz at room temperature. - Highlights: • We prepared Mn{sub 0.85}Zn{sub 0.15}Ni{sub x}Fe{sub 2}O{sub 4} (x=0.03, 0.06, 0.09, 0.12 and 0.15) nano-ferrite materials by using sol-gel method. • All the compounds characterized by XRD, SEM, VSM, ESR and dielectric studies. • We get lower coercivity values. • We get good results from ESR spectra.

The overview and history of permanent magnet devices in accelerator technology

International Nuclear Information System (INIS)

Kraus, R.H.

1994-01-01

This paper looks at the early history of accelerator development with a particular focus on the important discoveries that opened the door for the application of permanent-magnet materials to this area of science. Researchers began to use permanent-magnet materials in particle accelerators soon after the invention of the alternating gradient principle, that showed magnetic fields could be used to control the transverse envelope of charged-particle beams. Since that time, permanent-magnet materials have found wide application in the modern charged particle accelerator. A brief history of permanent-magnet use in accelerator physics and technology is outlined, some of the general design considerations are presented, and several material properties of concern for particle accelerator applications are discussed

The overview and history of permanent magnet devices in accelerator technology

International Nuclear Information System (INIS)

Kraus, R.H. Jr.

1993-01-01

This paper reviews the early history of accelerator development with a particular focus on the important discoveries that opened the door for the application of permanent-magnet materials to this area of science. Researchers began to use permanent-magnet materials in particle accelerators soon after the invention of the alternating gradient principle, that showed magnetic fields could be used to control the transverse envelope of charged-particle beams. Since that time, permanent-magnet materials have found wide application in the modern charged particle accelerator. The history of permanent-magnet use in accelerator physics and technology is outlined, general design considerations are presented, and material properties of concern for particle accelerator applications are discussed

Variable high gradient permanent magnet quadrupole (QUAPEVA)

Science.gov (United States)

Marteau, F.; Ghaith, A.; N'Gotta, P.; Benabderrahmane, C.; Valléau, M.; Kitegi, C.; Loulergue, A.; Vétéran, J.; Sebdaoui, M.; André, T.; Le Bec, G.; Chavanne, J.; Vallerand, C.; Oumbarek, D.; Cosson, O.; Forest, F.; Jivkov, P.; Lancelot, J. L.; Couprie, M. E.

2017-12-01

Different applications such as laser plasma acceleration, colliders, and diffraction limited light sources require high gradient quadrupoles, with strength that can reach up to 200 T/m for a typical 10 mm bore diameter. We present here a permanent magnet based quadrupole (so-called QUAPEVA) composed of a Halbach ring and surrounded by four permanent magnet cylinders. Its design including magnetic simulation modeling enabling us to reach 201 T/m with a gradient variability of 45% and mechanical issues are reported. Magnetic measurements of seven systems of different lengths are presented and confirmed the theoretical expectations. The variation of the magnetic center while changing the gradient strength is ±10 μm. A triplet of QUAPEVA magnets is used to efficiently focus a beam with large energy spread and high divergence that is generated by a Laser Plasma Acceleration source for a free electron laser demonstration and has enabled us to perform beam based alignment and control the dispersion of the beam.

Design and construction of permanent magnetic gears

DEFF Research Database (Denmark)

Jørgensen, Frank Thorleif

/l]. Measurement from this gear has resulted in a measured total torque density of 23 [Nm/l]. Mechanical versions of this gear type are found with total torque density in the 16 to 31 [Nm/l] range. The third and last gear technology that is investigated is a gear that reminds of a planetary gear. Research shows......This thesis deals with design and development of permanent magnetic gears. The goal of this thesis is to develop knowledge and calculation software for magnetic gears. They use strong NdFeB permanent magnets and a new magnetic gear technology, which will be a serious alternative to classical...... mechanical gears. The new magnetic gear will have a high torque density1 relationship –high efficiency and are maintenance free. In this project was manufactured two test gears which is tested and verified with models developed in this project. Present technological status for magnetic gears is introduced...

Study of the magnetic characteristics of ferrites with a view to their application in a proton synchrotron

International Nuclear Information System (INIS)

Nguyen, K.C.

1966-10-01

In this report magnetic properties of some Ni Zn ferrites available in France are investigated for the purpose of their use in accelerating cavities of proton synchrotron. An attempt is made to measure permeability and quality factor of ferrite versus various physical parameters such as frequency F, the induction B, the magnetic bias field Hp and the temperature, the investigation ranges being: F ≤ 40 Mc/s; B ≤ 10 -2 Tesla; Hp ≤ 5000 AT/m; T ≤ 100 C. The measurements were carried out with the one hand, conventional impedance bridge (Q-meter, RX-meter) and on the other hand, with resonating method using an inductive ferrite loaded cavity in parallel with an external capacity. The latter method is of particular interest for the measurements in function of induction and magnetic bias field. (author) [fr

Theory and design of a tunable antenna on a partially magnetized ferrite LTCC substrate

KAUST Repository

Ghaffar, Farhan A.; Bray, Joey R.; Shamim, Atif

2014-01-01

For the first time, a theoretical model is presented to predict the frequency tuning of a patch antenna on a partially magnetized ferrite substrate. Both extraordinary (E) and ordinary (O) modes of the antenna are studied. The permeability tensor of the partially magnetized ferrite is calculated through the proposed theoretical model and is subsequently used to analyze the antenna's performance in a microwave simulator. Prototype antennas were built, using two different bias windings, embedded in a multilayer ferrite LTCC substrate, to demonstrate E and O mode tuning. The use of embedded windings negates the requirement of bulky electromagnets, thus providing miniaturization. The concept also eliminates the demagnetization effect, thus reducing the typically required bias fields by 95%. The prototype measurements at 13 GHz demonstrate an E-mode tuning range of 10%. The proposed theoretical model has been validated by simulations and measurements. The design is highly suitable for compact, light-weight, tunable and reconfigurable microwave systems. © 1963-2012 IEEE.

Theory and design of a tunable antenna on a partially magnetized ferrite LTCC substrate

KAUST Repository

Ghaffar, Farhan A.

2014-03-01

For the first time, a theoretical model is presented to predict the frequency tuning of a patch antenna on a partially magnetized ferrite substrate. Both extraordinary (E) and ordinary (O) modes of the antenna are studied. The permeability tensor of the partially magnetized ferrite is calculated through the proposed theoretical model and is subsequently used to analyze the antenna\\'s performance in a microwave simulator. Prototype antennas were built, using two different bias windings, embedded in a multilayer ferrite LTCC substrate, to demonstrate E and O mode tuning. The use of embedded windings negates the requirement of bulky electromagnets, thus providing miniaturization. The concept also eliminates the demagnetization effect, thus reducing the typically required bias fields by 95%. The prototype measurements at 13 GHz demonstrate an E-mode tuning range of 10%. The proposed theoretical model has been validated by simulations and measurements. The design is highly suitable for compact, light-weight, tunable and reconfigurable microwave systems. © 1963-2012 IEEE.

Dovetail Rotor Construction For Permanent-Magnet Motors

Science.gov (United States)

Kintz, Lawrence J., Jr.; Puskas, William J.

1988-01-01

New way of mounting magnets in permanent-magnet, electronically commutated, brushless dc motors. Magnets wedge shaped, tapering toward center of rotor. Oppositely tapered pole pieces, electron-beam welded to rotor hub, retain magnets against centrifugal force generated by spinning rotor. To avoid excessively long electron-beam welds, pole pieces assembled in segments rather than single long bars.

Analysis and design of permanent magnet biased magnetic bearing based on hybrid factor

Directory of Open Access Journals (Sweden)

Jinji Sun

2016-03-01

Full Text Available In this article, hybrid factor is proposed for hybrid magnetic bearing. The hybrid factor is defined as the ratio of the force produced by the permanent magnet and the forces produced by the permanent magnet and current in hybrid magnetic bearing. It is deduced from a certain radial hybrid magnetic bearing using its important parameters such as the current stiffness and displacement stiffness at first and then the dynamic model of magnetically suspended rotor system is established. The relationship between structural parameters and control system parameters is analyzed based on the hybrid factor. Some influencing factors of hybrid factor in hybrid magnetic bearing, such as the size of the permanent magnet, length of air gap, and area of the stator poles, are analyzed in this article. It can be concluded that larger hybrid factor can be caused by the smaller power loss according to the definition of hybrid factor mentioned above. Meanwhile, the hybrid factor has a maximum value, which is related to control system parameters such as proportional factor expect for structural parameters. Finally, the design steps of parameters of hybrid magnetic bearing can be concluded.

Magnetic and magnetoelastic properties of M-substituted cobalt ferrites (M=Mn, Cr, Ga, Ge)

Energy Technology Data Exchange (ETDEWEB)

Song, Sang-Hoon [Iowa State Univ., Ames, IA (United States)

2007-12-15

Magnetic and magnetoelastic properties of a series of M-substituted cobalt ferrites, CoM_xFe_2-xO₄ (M=Mn, Cr, Ga; x=0.0 to 0.8) and Ge-substituted cobalt ferrites Co_1+xGe_xFe_2-2xO₄ (x=0.0 to 0.6) have been investigated.

Economic viability, applications and limits of efficient permanent magnet motors - Summary and update; Wirtschaftlichkeit, Anwendungen und Grenzen von effizienten Permanent-Magnet-Motoren - Zusammenfassung und Update - Schlussbericht

Energy Technology Data Exchange (ETDEWEB)

Lindegger, M. [Circle Motor AG, Guemligen (Switzerland); Biner, H.-P.; Evequoz, B. [Hochschule Westschweiz, Delemont (Switzerland); Salathe, D. [Hochschule Luzern Technik und Architektur, Horw (Switzerland)

2009-06-15

This final report for the Swiss Federal Office of Energy (SFOE), takes a look at the economic viability, applications and limits of efficient permanent magnet motors. Permanent magnet motors are compared with standard IEC asynchronous motors. In a theoretical part of the report, it is discussed how the increasing size of the motor influences efficiency, weight, volume and power. The results of practical tests carried out on six motors are presented. Three standard motors with varying efficiency were compared with three permanent-magnet motors for the power range around 3 kW. Market-oriented considerations concerning permanent-magnet motors are discussed. Operational criteria for the choice of the type of motor to be used are also examined.

On a neutral particle with permanent magnetic dipole moment in a magnetic medium

Science.gov (United States)

Bakke, K.; Salvador, C.

2018-03-01

We investigate quantum effects that stem from the interaction of a permanent magnetic dipole moment of a neutral particle with an electric field in a magnetic medium. We consider a long non-conductor cylinder that possesses a uniform distribution of electric charges and a non-uniform magnetization. We discuss the possibility of achieving this non-uniform magnetization from the experimental point of view. Besides, due to this non-uniform magnetization, the permanent magnetic dipole moment of the neutral particle also interacts with a non-uniform magnetic field. This interaction gives rise to a linear scalar potential. Then, we show that bound states solutions to the Schrödinger-Pauli equation can be achieved.

Post-assembly magnetization of a 100 kW high speed permanent magnet rotor.

Science.gov (United States)

Lv, Yiliang; Wang, Guobin; Li, Liang

2015-03-01

A post-assembly magnetizing fixture has been designed and successfully used to magnetize the rotor of a 100 kW high speed permanent magnet synchronous motor. The rotor is a solid cylinder with outer diameter of 80 mm and total length of 515 mm. The permanent magnet material is samarium-cobalt (Sm2Co17) with saturation magnetizing field of 6 T. The mechanical stability of the magnetizing fixture has been studied as well as the general design methodology. The magnetizing coil is subdivided in order to reduce the electromagnetic force, and the coils are separately reinforced in different ways. The electromagnetic and structural optimization is performed by finite element analysis and verified by experiments.

Post-assembly magnetization of a 100 kW high speed permanent magnet rotor

International Nuclear Information System (INIS)

Lv, Yiliang; Wang, Guobin; Li, Liang

2015-01-01

A post-assembly magnetizing fixture has been designed and successfully used to magnetize the rotor of a 100 kW high speed permanent magnet synchronous motor. The rotor is a solid cylinder with outer diameter of 80 mm and total length of 515 mm. The permanent magnet material is samarium-cobalt (Sm 2 Co 17 ) with saturation magnetizing field of 6 T. The mechanical stability of the magnetizing fixture has been studied as well as the general design methodology. The magnetizing coil is subdivided in order to reduce the electromagnetic force, and the coils are separately reinforced in different ways. The electromagnetic and structural optimization is performed by finite element analysis and verified by experiments

Post-assembly magnetization of a 100 kW high speed permanent magnet rotor

Energy Technology Data Exchange (ETDEWEB)

Lv, Yiliang; Wang, Guobin [Wuhan National High Magnetic Field Center, Huazhong University of Science and Technology, Wuhan (China); Li, Liang [Wuhan National High Magnetic Field Center, Huazhong University of Science and Technology, Wuhan (China); State Key Laboratory of Advanced Electromagnetic Engineering and Technology, Huazhong University of Science and Technology, Wuhan (China)

2015-03-15

A post-assembly magnetizing fixture has been designed and successfully used to magnetize the rotor of a 100 kW high speed permanent magnet synchronous motor. The rotor is a solid cylinder with outer diameter of 80 mm and total length of 515 mm. The permanent magnet material is samarium-cobalt (Sm{sub 2}Co{sub 17}) with saturation magnetizing field of 6 T. The mechanical stability of the magnetizing fixture has been studied as well as the general design methodology. The magnetizing coil is subdivided in order to reduce the electromagnetic force, and the coils are separately reinforced in different ways. The electromagnetic and structural optimization is performed by finite element analysis and verified by experiments.

Structural, morphological and magnetic properties of Eu-doped CoFe2O4 nano-ferrites

Directory of Open Access Journals (Sweden)

Aiman Zubair

Full Text Available Europium (Eu doped spinel cobalt ferrites having composition CoEuxFe2−xO4 where x = 0.00, 0.03, 0.06, 0.09, 0.12 were fabricated by co-precipitation route. In order to observe the phase development of the ferrite samples, thermo-gravimetric analysis was carried out. The synthesized samples were subjected to X-ray diffraction analysis for structural investigation. All the samples were found to constitute face centered cubic (FCC spinel structure belonging to Fd3m space group. Scanning electron microscopy revealed the formation of nanocrystalline grains with spherical shape. Energy dispersive X-ray spectra confirmed the presence of Co, Eu, Fe and O elements with no existence of any impurity. The magnetic hysteresis curves measured at room temperature exhibited ferrimagnetic behavior with maximum saturation magnetization (Ms of 65 emu/g and coercivity (Hc of 966 Oe. The origin of ferrimagnetism in Eu doped cobalt ferrites was discussed in detail with reverence to the allocation of Co2+ and Fe3+ ions within the spinel lattice. The overall coercivity was increased (944–966 Oe and magnetization was decreased (65–46 emu/g with the substitution of Eu3+. The enhancement of former is ascribed to the transition from multi domain to single domain state and reduction in lateral is attributed to the incorporation of nonmagnetic Eu ions for Fe, resulting in weak superexchange interactions. Keywords: Europium doped cobalt ferrites, Co-precipitation, X-ray diffraction, Scanning electron microscopy, Magnetic properties

Advanced optimization of permanent magnet wigglers using a genetic algorithm

Energy Technology Data Exchange (ETDEWEB)

Hajima, Ryoichi [Univ. of Tokyo (Japan)

1995-12-31

In permanent magnet wigglers, magnetic imperfection of each magnet piece causes field error. This field error can be reduced or compensated by sorting magnet pieces in proper order. We showed a genetic algorithm has good property for this sorting scheme. In this paper, this optimization scheme is applied to the case of permanent magnets which have errors in the direction of field. The result shows the genetic algorithm is superior to other algorithms.

Advanced optimization of permanent magnet wigglers using a genetic algorithm

International Nuclear Information System (INIS)

Hajima, Ryoichi

1995-01-01

In permanent magnet wigglers, magnetic imperfection of each magnet piece causes field error. This field error can be reduced or compensated by sorting magnet pieces in proper order. We showed a genetic algorithm has good property for this sorting scheme. In this paper, this optimization scheme is applied to the case of permanent magnets which have errors in the direction of field. The result shows the genetic algorithm is superior to other algorithms

Water flow patterns induced by bridge oscillation of magnetic fluid between two permanent magnets subjected to alternating magnetic field

International Nuclear Information System (INIS)

Sudo, Seiichi; Yamamoto, Kazuki; Ishimoto, Yukitaka; Nix, Stephanie

2017-01-01

This paper describes the characteristics of water flow induced by the bridge oscillation of magnetic fluid between two permanent magnets subject to an external alternating magnetic field. The magnetic fluid bridge is formed in the space between a pair of identical coaxial cylindrical permanent magnets submerged in water. The direction of alternating magnetic field is parallel /antiparallel to the magnetic field produced by two permanent magnets. The magnetic fluid bridge responds to the external alternating magnetic field with harmonic oscillation. The oscillation of magnetic fluid bridge generates water flow around the bridge. Water flow is visualized using a thin milk film at the container bottom. Water flows are observed with a high-speed video camera analysis system. The experimental results show that the flow pattern induced by the bridge oscillation depends on the Keulegan–Carpenter number.

Water flow patterns induced by bridge oscillation of magnetic fluid between two permanent magnets subjected to alternating magnetic field

Energy Technology Data Exchange (ETDEWEB)

Sudo, Seiichi, E-mail: sudo@akita-pu.ac.jp [Faculty of Systems Science and Technology, Akita Prefectural University, Ebinokuchi 84-4, Yurihonjo 015-0055 (Japan); Yamamoto, Kazuki [Graduate School of Engineering, Tohoku University, Katahira 2-1-1, Aoba-ku, Sendai 980-8577 (Japan); Ishimoto, Yukitaka; Nix, Stephanie [Faculty of Systems Science and Technology, Akita Prefectural University, Ebinokuchi 84-4, Yurihonjo 015-0055 (Japan)

2017-06-01

This paper describes the characteristics of water flow induced by the bridge oscillation of magnetic fluid between two permanent magnets subject to an external alternating magnetic field. The magnetic fluid bridge is formed in the space between a pair of identical coaxial cylindrical permanent magnets submerged in water. The direction of alternating magnetic field is parallel /antiparallel to the magnetic field produced by two permanent magnets. The magnetic fluid bridge responds to the external alternating magnetic field with harmonic oscillation. The oscillation of magnetic fluid bridge generates water flow around the bridge. Water flow is visualized using a thin milk film at the container bottom. Water flows are observed with a high-speed video camera analysis system. The experimental results show that the flow pattern induced by the bridge oscillation depends on the Keulegan–Carpenter number.

Tunable bandpass filter based on partially magnetized ferrite LTCC with embedded windings for SoP applications

KAUST Repository

Arabi, Eyad A.

2015-01-01

Tunable filters that are based on ferrite materials often require large and bulky electromagnets. In this work, we present a tunable filter in the Ku-band, which is realized in multilayer ferrite LTCC substrate with embedded bias windings, thus negating the need of a large electromagnet. Also, because of the embedded windings, the bias fields are not lost at the air-substrate interface and therefore the field and current requirements are reduced by an order of magnitude as compared to the previously reported filters. A simulation strategy that uses full permeability tensor with arbitrarily directed magnetic fields has been used to model the filter on a partially magnetized ferrite substrate. Special attention has also been paid to approximate the non-uniform magneto-static fields produced by the embedded windings. The complete design is implemented in 10 layers of ferrite LTCC, making it the first magnetically tunable filter with embedded windings and extremely small size [(5 × 5 × 1.1)mm3]. The filter demonstrates a measured tunability of 4% and an insertion loss of 2.3 dB. With the small form factor, embedded windings, and low bias requirements, the design is highly suitable for compact and tunable SoP applications.

Influence of cold isostatic pressing on the magnetic properties of Ni-Zn-Cu ferrite

Science.gov (United States)

Le, Trong Trung; Valdez-Nava, Zarel; Lebey, Thierry; Mazaleyrat, Frédéric

2018-04-01

In power electronics, there is the need to develop solutions to increase the power density of converters. Interleaved multicellular transformers allow interleaving many switching cells and, as a result, a possible increase in the power density. This converter is often composed of a magnetic core having the function of an intercell transformer (ICT) and, depending on the complexity of the designed architecture, its shape could be extremely complex. The switching frequencies (1-10 MHz) for the new wide band gap semiconductors (SiC, GaN) allow to interleave switching cell at higher frequencies than silicon-based semiconductors (materials, but their limit in frequency drive raises the need of higher frequency magnetic materials, such Ni-Zn ferrites. These materials can operate in medium and high power converters up to 10 MHz. We propose to use Ni0,30Zn0,57Cu0,15Fe2O4 ferrite and to compress it by cold isostatic pressing (CIP) into a a green ceramic block and to machine it to obtain the desired ICT of complex shape prior sintering. We compare the magnetic permeability spectra and hysteresis loops the CIP and uniaxially pressed ferrites. The effect of temperature and sintering time as well as high-pressure on properties will be presented in detail. The magnetic properties of the sintered cores are strongly dependent on the microstructure obtained.

Magnetic properties of mixed Ni–Cu ferrites calculated using mean field approach

Energy Technology Data Exchange (ETDEWEB)

Masrour, R., E-mail: rachidmasrour@hotmail.com [Laboratory of Materials, Processes, Environment and Quality, Cady Ayyed University, National School of Applied Sciences, 63, 46000 Safi (Morocco); LMPHE, URAC 12, Faculté des Sciences, Université Mohamed V-Agdal, Rabat (Morocco); Hamedoun, M. [Institute for Nanomaterials and Nanotechnologies, MAScIR, Rabat (Morocco); Benyoussef, A. [LMPHE, URAC 12, Faculté des Sciences, Université Mohamed V-Agdal, Rabat (Morocco); Institute for Nanomaterials and Nanotechnologies, MAScIR, Rabat (Morocco); Academie Hassan II des Sciences et Techniques, Rabat (Morocco); Hlil, E.K. [Institut Néel, CNRS et Université Joseph Fourier, BP 166, F-38042 Grenoble cedex 9 (France)

2014-08-01

The magnetic properties of spinel ferrites [Fe{sub 1−(1−x)y}{sup 3+}Cu{sub (1−x)y}{sup 2+}]{sub A}[Ni{sub x}{sup 2+}Cu{sub (1−x)(1−y)}{sup 2+}Fe{sub 1+(1−x)y}{sup 3+}]{sub B}O{sub 4} have been studied by the mean field theory (MFT) and high temperature series expansions (HTSEs) combined with the Padé approximants. The critical temperature, the saturation magnetisation (M{sub S}) and the intra-sublattice exchanges interactions (J{sub AA}(x,y), J{sub BB}(x,y) and J{sub AB}(x,y)) are obtained by using a probability distribution law. The critical exponents associate with the magnetic susceptibility have been obtained. The effect of copper doping on the magnetic properties of nickel ferrites has been examined. - Highlights: • The exchange and constants interactions of CuFe{sub 2}O{sub 4} material are obtained. • The saturation magnetisation, the critical temperature, the Curie Weiss temperature and the Curie constant of CuFe{sub 2}O{sub 4} are obtained. • The critical exponent associated with the magnetic susceptibility is given.

Magnetic properties and densification of Manganese-Zinc soft ferrites (Mn1-xZnxFe2O4) doped with low melting point oxides

International Nuclear Information System (INIS)

Shokrollahi, H.

2008-01-01

Mn-Zn ferrites have high electrical resistivity, low power loss and high initial permeability up to several MHz range. Oxide additives can greatly affect the magnetic properties of these ferrites. The effects of the additives on the sintering behaviour and magnetic properties of Mn-Zn ferrites are different. Some low melting point additives such as Bi 2 O 3 enhance the sintering by forming a liquid phase in the ferrites. The additive V 2 O 5 enhances the sintering by increasing bulk diffusion due to the increased vacancy concentration which is accompanied by the solubility of V 5+ in the ferrites. Some additives are cations that are soluble in the host lattice and enter regular positions on the tetrahedral or octahedral sites. This paper investigates the effect of several low melting point oxides on the magnetic properties, microstructure and densification of Mn-Zn soft ferrites

Permanent-magnet-less machine having an enclosed air gap

Science.gov (United States)

Hsu, John S [Oak Ridge, TN

2012-02-07

A permanent magnet-less, brushless synchronous system includes a stator that generates a magnetic rotating field when sourced by an alternating current. An uncluttered rotor disposed within the magnetic rotating field is spaced apart from the stator to form an air gap relative to an axis of rotation. A stationary excitation core spaced apart from the uncluttered rotor by an axial air gap and a radial air gap substantially encloses the stationary excitation core. Some permanent magnet-less, brushless synchronous systems include stator core gaps to reduce axial flux flow. Some permanent magnet-less, brushless synchronous systems include an uncluttered rotor coupled to outer laminations. The quadrature-axis inductance may be increased in some synchronous systems. Some synchronous systems convert energy such as mechanical energy into electrical energy (e.g., a generator); other synchronous systems may convert any form of energy into mechanical energy (e.g., a motor).

Structural and magnetic properties of ball milled copper ferrite

DEFF Research Database (Denmark)

Goya, G.F.; Rechenberg, H.R.; Jiang, Jianzhong

1998-01-01

The structural and magnetic evolution in copper ferrite (CuFe2O4) caused by high-energy ball milling are investigated by x-ray diffraction, Mössbauer spectroscopy, and magnetization measurements. Initially, the milling process reduces the average grain size of CuFe2O4 to about 6 nm and induces....... The canted spin configuration is also suggested by the observed reduction in magnetization of particles in the blocked state. Upon increasing the milling time, nanometer-sized CuFe2O4 particles decompose, forming alpha-Fe2O3 and other phases, causing a further decrease of magnetization. After a milling time...... of 98 h, alpha-Fe2O3 is reduced to Fe3O4, and magnetization increases accordingly to the higher saturation magnetization value of magnetite. Three sequential processes during high-energy ball milling are established: (a) the synthesis of partially inverted CuFe2O4 particles with a noncollinear spin...

Streaming flows produced by oscillating interface of magnetic fluid adsorbed on a permanent magnet in alternating magnetic field

Science.gov (United States)

Sudo, S.; Ito, M.; Ishimoto, Y.; Nix, S.

2017-04-01

This paper describes microstreaming flows generated by oscillating interface of magnetic fluid adsorbed on a circular cylindrical permanent magnet in alternating magnetic field. The interface of magnetic fluid adsorbed on the NdFeB magnet responds to the external alternating magnetic flied as harmonic oscillation. The directions of alternating magnetic field are parallel and antiparallel to the magnetic field of permanent magnet. The oscillation of magnetic fluid interface generates streaming flow around the magnet-magnetic fluid element in water. Microstreaming flows are observed with a high-speed video camera analysis system. The flow pattern generated by magnetic fluid motion depends on the Keulegan-Carpenter number and the Reynolds number.

Cobalt-Free Permanent Magnet Alloys.

Science.gov (United States)

1984-10-01

ThC Ferrites (Zn, Mn. Cu, Fe)O A12O. Al TiC Kaolin Al203.Si02-Fe2O3 Fe2O3 Li B4C Spodumene LiAI (SiOs) 2 ThO2 Ni UC Rhodonite NtnO. SiO2 MnOs Fe TaC...minutes. X-ray diffraction pattern indicated the presence of magnetic T phase. Hysteresis loop was measured on the heat treated powder dispersed in wax...fmgei * T phse Hysersi loo was mesue on the. heat - treated ,--". " powder dispersed in wax... The’ result wer as"- follows: • , " • "• . I TABLE 6

Sensorless V/f Control of Permanent Magnet Synchronous Motors

OpenAIRE

Montesinos-Miracle, Daniel; Perera, P. D. Chandana; Galceran-Arellano, Samuel; Blaabjerg, Frede

2010-01-01

V/f control strategy for permanent magnet synchronous motors can be useful for HVAC applications, where not high performance is required. Permanent magnet synchronous motors have efficiency advantages over the induction motor. But open loop V/f control is not stable in the whole frequency range. As demonstrated, the V/f control strategy becomes

Regulation of fields excited by permanent magnets

International Nuclear Information System (INIS)

Savchenko, I.S.

1989-01-01

Two methods of fast regulation of fields excited by permanent magnets in salient-pole electron-optical lenses are described: 1)the hybrid method realized using the additional electromagnet introduced to a magnetic chain sequentially its field being composed or substracted with magnetosolid exciter field; 2)the method with saturation of a part of a magnetic circuit, with saturation being achievable at the begining or in the end of a regulation cycle. In the second method it is proposed to direct orthogonally the main flux excited by permanent magnets and the flux in the saturated part of the magnetic circuit excited using an electromagnet. It is shown that the second method allows one to reduce the required ampere-coils by more than an order as compared to the first method at one and the same regulation range and other equal conditions. The frequency of field regulation in the experimental mock-up was 10 kHz. 3 refs.; 2 figs

Permanent magnets for production and use of high energy particle beams

International Nuclear Information System (INIS)

Halbach, K.

1985-03-01

In the last few years, permanent magnet systems have begun to play a dominant role in the generation of synchrotron radiation and the operation of free electron lasers. Similarly, permanent magnets can lead to significant improvements of accelerators and systems that use them. The general conditions are discussed under which one can expect benefits from permanent magnets, and a number of specific applications will be described in detail

Effect of Mg substitution on the magnetic properties of Ni–Zn ferrites

Indian Academy of Sciences (India)

Y Ramesh Babu

2017-05-31

May 31, 2017 ... C for 6h in air to investigate their structural and magnetic properties. X-ray diffraction ... The tetrava- lent substitutions have been found to improve the .... ducted on ferrites prepared by ceramic method [11] and wet chemical ...

Magnetic materials based on manganese–zinc ferrite with surface organized polyaniline coating

Czech Academy of Sciences Publication Activity Database

Kazantseva, N. E.; Bespyatykh, Y.; Sapurina, I.; Stejskal, Jaroslav; Vilčáková, J.; Sáha, P.

2006-01-01

Roč. 301, č. 1 (2006), s. 155-165 ISSN 0304-8853 R&D Projects: GA AV ČR IAA4050313 Keywords : ferrite * coated particles * conducting polymer Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 1.212, year: 2006

Development of Disk Rover, wall-climbing robot using permanent magnet disk

International Nuclear Information System (INIS)

Hirose, Shigeo; Tsutsumitake; Hiroshi; Toyama, Ryousei; Kobayashi, Kengo.

1992-01-01

A new type of wall climbing robot, named Disk Rover, using permanent magnet disks are developed. The newly introduced permanent magnet disk is to rotate the magnet disk on the surface of wall with partly contacted posture. It allows to produce high magnetic attraction force compared with conventional permanent wheel which utilizes only a small portion of the magnet installed around the wheel. The optimum design of the magnetic wheel is done by using finit element method and it is shown that the magnetic attraction force vs. weight ratio can be designed about three times higher than conventional type magnet wheel. The developed Disk Rover is 25 kg in weight including controller and battery, about 685 mm in diameter, 239 mm in height and has a pair of permanent magnet disks. It is demonstrated by the experiments that the Disk Rover can move around on the surface of the wall quite smoothly by radio control and has payload of about its own weight. Several considerations are also done in order to surmount bead weld. (author)

Permanent-magnet switched-flux machine

Science.gov (United States)

Trzynadlowski, Andrzej M.; Qin, Ling

2010-01-12

A permanent-magnet switched-flux (PMSF) device has a ferromagnetic outer stator mounted to a shaft about a central axis extending axially through the PMSF device. Pluralities of top and bottom stator poles are respectively mounted in first and second circles, radially outwardly in first and second transverse planes extending from first and second sections of the central axis adjacent to an inner surface of the ferromagnetic outer stator. A ferromagnetic inner rotor is coupled to the shaft and has i) a rotor core having a core axis co-axial with the central axis; and ii) first and second discs having respective outer edges with first and second pluralities of permanent magnets (PMs) mounted in first and second circles, radially outwardly from the rotor core axis in the first and second transverse planes. The first and second pluralities of PMs each include PMs of alternating polarity.

Structural and magnetic properties of cadmium substituted manganese ferrites prepared by hydrothermal route

Energy Technology Data Exchange (ETDEWEB)

Mostafa, Nasser Y., E-mail: nmost69@yahoo.com [Faculty of Science, Taif University, P.O. Box: 888, Al-Haweiah, Taif (Saudi Arabia); Chemistry Department, Faculty of Science, Suez Canal University, Ismailia 41522 (Egypt); Zaki, Z.I. [Faculty of Science, Taif University, P.O. Box: 888, Al-Haweiah, Taif (Saudi Arabia); Advanced Materials Division, Central Metallurgical R and D Institute (CMRDI), P.O. Box: 87 Helwan, Cairo (Egypt); Heiba, Z.K. [Faculty of Science, Taif University, P.O. Box: 888, Al-Haweiah, Taif (Saudi Arabia); Physics Department, Faculty of Science, Ain Shams University, Cairo (Egypt)

2013-03-15

Cd-substituted manganese ferrite Mn{sub 1-x}Cd{sub x}Fe{sub 2}O{sub 4} powders with x having values 0.0, 0.1, 0.3 and 0.5 have been synthesized by hydrothermal route at 180 Degree-Sign C in presence of NaOH as mineralizer. The obtained ferrite samples were characterized by X-ray diffraction (XRD), transmission electron microscope (TEM) and vibrating sample magnetometer (VSM). The XRD analysis showed that pure single phases of cubic ferrites were obtained with x upto 0.3. However, sample with x{>=}0.5 showed hexagonal phase of cadmium hydroxide (Cd(OH){sub 2}) besides the ferrite phase. The increase in Cd-substitution upto x=0.3 leads to an increase in the lattice parameter as well as the average crystallite size of the prepared ferrites. The average crystallite size increased by increasing the Cd-content and was in the range of 39-57 nm. According to VSM results, the saturation magnetization increased with Cd ion substitution. - Highlights: Black-Right-Pointing-Pointer Hydrothermal synthesized of mono dispersed Cd-substituted MnFe{sub 2}O{sub 4} nanoparticles. Black-Right-Pointing-Pointer The change in Ms with increasing Cd-substitution was investigated Black-Right-Pointing-Pointer Pure single phases of cubic ferrites were obtained with x up to 0.3 Black-Right-Pointing-Pointer Sample with x{>=}0.5 showed hexagonal phase of Cd(OH){sub 2} beside the ferrite.

Glass additive influence on the sintering behavior, microstructure and microwave magnetic properties of Cu-Bi-Zn co-doped Co2Z ferrites

International Nuclear Information System (INIS)

Hsiang, Hsing-I; Mei, Li-Then; Hsi, Chi-Shiung; Wu, Wei-Cheng; Cheng, Li-Bao; Yen, Fu-Su

2011-01-01

The Bi 2 O 3 -B 2 O 3 -ZnO-SiO 2 (BB35SZ) glass effects on the sintering behavior and microwave magnetic properties of Cu-Bi-Zn co-doped Co 2 Z ferrites were investigated to develop low-temperature-fired ferrites. The glass wetting characteristics on the Co 2 Z ferrite surface, X-ray diffractometer, scanning electron microscopy and a dilatometer were used to examine the BB35SZ glass effect on Co 2 Z ferrite densification and the chemical reaction between the glass and Co 2 Z ferrites. The results indicate that BB35SZ glass can be used as a sintering aid to reduce the densification temperature of Co 2 Z ferrites from 1300 to 900 o C. 3(Ba 0.9 Bi 0.1 O).2(Co 0.8 Cu 0.2 O).12(Fe 1.975 Zn 0.025 O 3 ) ferrite with 2 wt% BB35SZ glass can be densified below 900 o C, exhibiting an initial permeability of 3.4. This process provides a promising candidate for multilayer chip magnetic devices for microwave applications. - Research highlights: → Bi 2 O 3 -B 2 O 3 -ZnO-SiO 2 glass can effectively wet Co 2 Z ferrites and promote Co 2 Z ferrite densification. → The excess substitution of Bi and Zn (x=0.2) and glass addition enhanced Z phase decomposition into U, W and spinel phases, which resulted in magnetic property degradation. → 3(Ba 0.9 Bi 0.1 O).2(Co 0.8 Cu 0.2 O).12(Fe 1.975 Zn 0.025 O 3 ) ferrite with 2 wt% glass can be densified at below 900 o C and exhibits an initial permeability of 3.4, which provides a promising candidate for multilayer chip magnetic devices for microwave applications.

A variable-field permanent-magnet dipole for accelerators

International Nuclear Information System (INIS)

Kraus, R.H. Jr.; Barlow, D.B.; Meyer, R.

1992-01-01

A new concept for a variable-field permanent-magnet dipole has been developed and fabricated at Los Alamos. The application requires an extremely uniform dipole field in the magnet aperture and precision variability over a large operating range. An iron-core permanent- magnet design using a shunt that was specially shaped to vary the field in a precise and reproducible fashion with shunt position. The key to this design is in the shape of the shunt. The field as a function of shunt position is very linear from 90% of the maximum field to 20% of the minimum field. The shaped shunt also results in a small maximum magnetic force attracting the shunt to the yoke allowing a simple mechanical design. Calculated and measured results agree well for the magnet

Influence of the interface on the magnetic properties of NiZn ferrite thin films treated by proton irradiation

Energy Technology Data Exchange (ETDEWEB)

Jiang, X.D. [Institute of Modern Physics, Chinese Academy of Sciences, Lanzhou 730000 (China); Key Laboratory for Magnetism and Magnetic Materials of the Ministry of Education, Lanzhou University, Lanzhou 730000 (China); Guo, D.W. [Key Laboratory for Magnetism and Magnetic Materials of the Ministry of Education, Lanzhou University, Lanzhou 730000 (China); Zhang, C.H., E-mail: c.h.zhang@impcas.ac.cn [Institute of Modern Physics, Chinese Academy of Sciences, Lanzhou 730000 (China); Fan, X.L.; Chai, G.Z. [Key Laboratory for Magnetism and Magnetic Materials of the Ministry of Education, Lanzhou University, Lanzhou 730000 (China); Xue, D.S., E-mail: xueds@lzu.edu.cn [Key Laboratory for Magnetism and Magnetic Materials of the Ministry of Education, Lanzhou University, Lanzhou 730000 (China)

2015-09-01

In order to systematically investigate the influence of the interface on the magnetic properties, polycrystalline NiZn ferrite thin films were irradiated with 60 keV proton in the dose range from 5 × 10{sup 12} to 5 × 10{sup 16} ions/cm{sup 2}. A non-destructive approach by proton irradiation was found to finely adjust the magnetic properties of polycrystalline NiZn ferrite thin films such as coercivity, perpendicular magnetic anisotropy as well as the effective g value. The coercivity is about 725 Oe for high proton dose ferrite, which is twice larger than the unirradiated one. The ferromagnetic resonance measurements indicated that perpendicular magnetic anisotropy and the effective g value increase with the irradiation dose. Our finding indicates that all modifications of these magnetic properties were associated with the change of interface due to the diffusion and the stress induced by proton irradiation. The change of the effective g value is a result of lattice expansion and the decrease of the magnetic dipole interaction between the columnar grains. This work provides a feasible way to tailor the magnetic properties of thin films by ion irradiation and promotes investigations for the stability of magnetic thin film devices in space or unclear radiation environments.

Implementation of Permanent Magnet Motors in Electric Vehicles

OpenAIRE

Elvestad, Eirik

2008-01-01

This thesis has studied permanent magnet motors in electric vehicles (EVs) under the assumption that they are tractable due to a low weight and high compactness. The implementation has been investigated through a case study, which resulted in an EV simulation model. The model contains a maximal torque per ampere and a closed-loop field weakening controller. Abstract Faults are a special concern in permanent magnet motors. Fault sources and faulted behavior are addressed separately. The EV mo...

Three-dimensional analytical field calculation of pyramidal-frustum shaped permanent magnets

NARCIS (Netherlands)

Janssen, J.L.G.; Paulides, J.J.H.; Lomonova, E.

2009-01-01

This paper presents a novel method to obtain fully analytical expressions of the magnetic field created by a pyramidal-frustum shaped permanent magnet. Conventional analytical tools only provide expressions for cuboidal permanent magnets and this paper extends these tools to more complex shapes. A

Synthesis, characterization and magnetic properties of monodisperse Ni, Zn-ferrite nanocrystals

Energy Technology Data Exchange (ETDEWEB)

Kumar, Sanjeev, E-mail: sanjeevkumar.dubey2@gmail.com [University of Petroleum and Energy Studies, Dehradun, Uttarakhand (India); Kumar, Pankaj [University of Petroleum and Energy Studies, Dehradun, Uttarakhand (India); Singh, Vaishali [University School of Basic and Applied Science (India); Kumar Mandal, Uttam [University of Chemical Technology, GGS Indraprastha University, Sector 16, Dwarka, Delhi 110403 (India); Kumar Kotnala, Ravinder [National Physical laboratory, New Delhi 110012 (India)

2015-04-01

Synthesization of monodisperse Ni, Zn-ferrite (Ni{sub 1−x}Zn{sub x}Fe{sub 2}O{sub 4}, x=1, 0.8, 0.6, 0.5, 0.4, 0.2, 0.0) nanocrystals has been achieved by the inverse microemulsion method using CTAB as surfactant and kerosene as an oil phase. The detailed characterization of the synthesized nanocrystals and measurement of the magnetic properties has been done by techniques like X-ray diffraction (XRD), field emission transmission electron microscopy (FETEM), Fourier transform infrared spectroscopy (FITR) and Vibrating Sample Magnetometer (VSM) respectively. The relationship between the structure and composition of the nanocrystals with magnetic properties has been investigated. The nanocrystals size is found to be in the range 1–5 nm. The effect of Zn substitution on size and magnetic properties has been studied. It has been observed that magnetism changed from ferromagnetic at X= 0 to super paramagnetic to paramagnetic at X=1 as Zn concentration increased. The Curie temperature is found to decrease with an increase in Zn concentration. - Highlights: • Reverse microemulsion route is very facile route for synthesis of Ni{sub 1−x}Zn{sub x}Fe{sub 2}O{sub 4} ferrite. • Presence of Zn changes the structural and magnetic properties of the Zn substituted NiFe{sub 2}O{sub 4.} • The lattice constant increases with the increase in Zn substitution. • The curie temperature decreases with Zn concentration appreciably. • Magnetic behavior varies from ferromagnetic at x=0 to superparamagnetic to paramagnetic at x=1.

A new type of permanent magnet ondulator and wiggler

International Nuclear Information System (INIS)

Jianming, X.; Maosan, L.; Qing, X.

1987-01-01

A new type of permanent magnet ondulator and wiggler is discussed. In this new design the magnet is composed of permanent magnet segments with modulated thickness. The magnetization directions of the segments are all perpendicular to the symmetrical plane of the magnet gap. By modulating the thicknesses of the segments, the field distribution is a pure sinusoidal curve in the ideal 2-dimensional case. The spatial expressions of the magnet field in the ideal case and in the real case are given. The methods for reducing the undesirable harmonics in the magnet field in the real case are discussed. Because of the arrangement of the magnetization directions of the magnet segments, soft iron shield can be used to strenghten the magnet field. In some cases, the stregnthening factor is more than two. The strenghtening effect of the soft iron shield is analysed also

Iron free permanent magnet systems for charged particle beam optics

International Nuclear Information System (INIS)

Lund, S.M.; Halbach, K.

1995-01-01

The strength and astounding simplicity of certain permanent magnet materials allow a wide variety of simple, compact configurations of high field strength and quality multipole magnets. Here we analyze the important class of iron-free permanent magnet systems for charged particle beam optics. The theory of conventional segmented multipole magnets formed from uniformly magnetized block magnets placed in regular arrays about a circular magnet aperture is reviewed. Practical multipole configurations resulting are presented that are capable of high and intermediate aperture field strengths. A new class of elliptical aperture magnets is presented within a model with continuously varying magnetization angle. Segmented versions of these magnets promise practical high field dipole and quadrupole magnets with an increased range of applicability

Design and control of a superconducting permanent magnet synchronous motor

International Nuclear Information System (INIS)

Jiang, Y; Pei, R; Hong, Z; Song, J; Fang, F; Coombs, T A

2007-01-01

This paper gives a detailed description of the design of a superconducting permanent magnet synchronous motor. The parameters of the motor have been identified, and the torque equation has been stated. A direct torque control algorithm is introduced and applied to a traditional permanent magnet synchronous motor and the superconducting permanent magnet synchronous motor described in this paper. The motor performance shows that the direct torque control algorithm provides excellent control to the superconducting motor, and guarantees that the magnitude of the operational armature currents is smaller than the value of the critical current of the superconducting tape used for stator winding

Design and control of a superconducting permanent magnet synchronous motor

Energy Technology Data Exchange (ETDEWEB)

Jiang, Y [Cambridge University Engineering Department, Trumpington Street, Cambridge CB2 1PZ (United Kingdom); Pei, R [Cambridge University Engineering Department, Trumpington Street, Cambridge CB2 1PZ (United Kingdom); Hong, Z [Cambridge University Engineering Department, Trumpington Street, Cambridge CB2 1PZ (United Kingdom); Song, J [Huazhong University of Science of Technology, Wuhan 430074 (China); Fang, F [Huazhong University of Science of Technology, Wuhan 430074 (China); Coombs, T A [Cambridge University Engineering Department, Trumpington Street, Cambridge CB2 1PZ (United Kingdom)

2007-07-15

This paper gives a detailed description of the design of a superconducting permanent magnet synchronous motor. The parameters of the motor have been identified, and the torque equation has been stated. A direct torque control algorithm is introduced and applied to a traditional permanent magnet synchronous motor and the superconducting permanent magnet synchronous motor described in this paper. The motor performance shows that the direct torque control algorithm provides excellent control to the superconducting motor, and guarantees that the magnitude of the operational armature currents is smaller than the value of the critical current of the superconducting tape used for stator winding.

Development of a hybrid bearing using permanent magnets and piezoelectric actuators

International Nuclear Information System (INIS)

Park, Jung-Ho; Ham, Young-Bog; Yun, So-Nam; Lee, Hu-Seung

2010-01-01

In this study, a hybrid magnetic bearing with permanent magnets and piezoelectric actuators is investigated. First, in this study, a novel concept in which piezoelectric actuators are used to compensate for low stiffness and damping resulting from the unstable characteristics of a passive magnetic bearing using only permanent magnets is proposed. Secondly, the permanent magnets are optimally arranged through an electromagnetic field analysis. Then, the driving amplifier unit and a prototype radial bearing using the proposed concept are fabricated. Finally, basic characteristics, such as the results of an impact test and a rotational runout test with constant speed are investigated and discussed, and experiments using PID control method are conducted.

Design, manufacture and measurements of permanent dipole magnets for DIRAC

CERN Document Server

Vorozhtsov, A; Kasaei, S; Solodko, E; Thonet, P A; Tommasini, D

2013-01-01

The one of the aim of the DIRAC experiment is the observation of the long-lived π+π- atoms, using the proton beam of the CERN Proton Synchrotron [1]. Two dipole magnets are needed for the for the DIRAC experiment as high resolution spectrometers. The dipole magnet will be used to identify the long-lived atoms on the high level background of π+π- pairs produced simultaneously with π+π- atoms. The proposed design is a permanent magnet dipole with a mechanical aperture of 60 mm. The magnet, of a total physical length of 66 mm, is based on Sm2Co17 blocks and provides an integrated field strength of 24·10-3 T×m. The Sm2Co17 was chosen as a material for the permanent magnet blocks due to its radiation hardness and weaker temperature dependence. The magnetic field quality is determined by 2 ferromagnetic poles, aligned together with the permanent magnets blocks. The paper describes the design, manufacture and magnetic measurements of the magnets.

Investigation of structural, optical, magnetic and electrical properties of tungsten doped Nisbnd Zn nano-ferrites

Science.gov (United States)

Pathania, Abhilash; Bhardwaj, Sanjay; Thakur, Shyam Singh; Mattei, Jean-Luc; Queffelec, Patrick; Panina, Larissa V.; Thakur, Preeti; Thakur, Atul

2018-02-01

Tungsten substituted nickel-zinc ferrite nanoparticles with chemical composition of Ni0.5Zn0.5WxFe2-xO4 (x = 0.0, 0.2, 0.4, 0.6, 0.8 & 1.0) were successfully synthesized by a chemical co-precipitation method. The prepared ferrites were pre sintered at 850 °C and then annealed at 1000 °C in a muffle furnace for 3 h each. This sintered powder was inspected by X-ray diffraction (XRD), transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FTIR), and vibrating sample magnetometer (VSM) to study the structural, optical, and magnetic properties. XRD measurement revealed the phase purity of all the nanoferrite samples with cubic spinel structure. The estimated crystallite size by X-ray line broadening is found in the range of 49-62 nm. FTIR spectra of all the samples have observed two prominent absorption bands in the range 400-700 cm-1 arising due to tetrahedral and octahedral stretching vibrations. Vibrating sample magnetometer experiments showed that the saturation magnetizations (MS) decreased with an increase in non-magnetic tungsten ion doping. The electrical resistivity of tungsten doped Nisbnd Zn nano ferrites were examined extensively as a function of temperature. With an increase in tungsten composition, resistivity was found to decrease from 2.2 × 105 Ω cm to 1.9 × 105 Ω cm which indicates the semiconducting behavior of the ferrite samples. The activation energy also decreased from 0.0264 to 0.0221 eV at x = 0.0 to x = 1.0. These low coercive field tungsten doped Nisbnd Zn ferrites are suitable for hyperthermia and sensor applications. These observations are explained in detail on the basis of various models and theories.

Rational design of the exchange-spring permanent magnet.

Science.gov (United States)

Jiang, J S; Bader, S D

2014-02-12

The development of the optimal exchange-spring permanent magnet balances exchange hardening, magnetization enhancement, and the feasibility of scalable fabrication. These requirements can be met with a rational design of the microstructural characteristics. The magnetization processes in several model exchange-spring structures with different geometries have been analyzed with both micromagnetic simulations and nucleation theory. The multilayer geometry and the soft-cylinders-in-hard-matrix geometry have the highest achievable figure of merit (BH)max, while the soft-spheres-in-hard-matrix geometry has the lowest upper limit for (BH)max. The cylindrical geometry permits the soft phase to be larger and does not require strict size control. Exchange-spring permanent magnets based on the cylindrical geometry may be amenable to scaled-up fabrication.

Rational design of the exchange-spring permanent magnet

International Nuclear Information System (INIS)

Jiang, J S; Bader, S D

2014-01-01

The development of the optimal exchange-spring permanent magnet balances exchange hardening, magnetization enhancement, and the feasibility of scalable fabrication. These requirements can be met with a rational design of the microstructural characteristics. The magnetization processes in several model exchange-spring structures with different geometries have been analyzed with both micromagnetic simulations and nucleation theory. The multilayer geometry and the soft-cylinders-in-hard-matrix geometry have the highest achievable figure of merit (BH) max , while the soft-spheres-in-hard-matrix geometry has the lowest upper limit for (BH) max . The cylindrical geometry permits the soft phase to be larger and does not require strict size control. Exchange-spring permanent magnets based on the cylindrical geometry may be amenable to scaled-up fabrication. (paper)

Effect of sintering temperature on magnetization and Mössbauer parameters of cobalt ferrite nanoparticles

Energy Technology Data Exchange (ETDEWEB)

Chandra, Grish, E-mail: grishphysics@gmail.com [Department of Physics, DSB Campus Kumaun University, Nainital 263002, Uttarakhand (India); Srivastava, R.C. [Department of Physics, GB Pant University of Agriculture and Technology, Pantnagar, Uttarakhand (India); Reddy, V.R. [UGC-DAE CSR, Khandwa Road, DAVV Campus, Indore 452017, Madhya Pradesh (India); Agrawal, H.M. [Department of Physics, GB Pant University of Agriculture and Technology, Pantnagar, Uttarakhand (India)

2017-04-01

Nanoparticles of cobalt ferrite of different particle size were prepared using sol-gel method. Powder X-ray diffraction (XRD), transmission electron microscopy (TEM), vibrating sample magnetometer (VSM) and Mössbauer spectroscopy techniques were employed for characterization of nanoparticles for structural and magnetic properties. The particle size and saturation magnetization increase with the increase of sintering temperature. The saturation magnetization increases from 53 to 85 emu/g as the sintering temperature increases from 300 to 900 °C. The remanence increases while the coercivity decreases slightly with the increase of sintering temperature. Mössbauer spectra show the ferrimagnetic nature of all the samples and the cation distribution strictly depends on the sintering temperature. The stoichiometry of the cobalt ferrite formed was estimated to be (Co{sup 2+}{sub x}Fe{sup 3+}{sub 1−x})[Co{sup 2+}{sub 1−x}Fe{sup 3+}{sub 1+x}]O{sub 4}, based on our Mössbauer analysis. The inverse spinel structure gradually transforms towards the normal spinel structure as the sintering temperature increases. - Highlights: • After 500 °C sintering the cobalt ferrite shows complete crystallization. • An inversion sintering temperature between 900 °C and 1200 °C is proposed where the Fe{sup +3} again starts migration from B site to A site. • Sintering temperature is one of the prime factors which effect the magnetization and cation distribution between two sites A and B.

Calcium-assisted reduction of cobalt ferrite nanoparticles for nanostructured iron cobalt with enhanced magnetic performance

International Nuclear Information System (INIS)

Qi, B.; Andrew, J. S.; Arnold, D. P.

2017-01-01

This paper demonstrates the potential of a calcium-assisted reduction process for synthesizing fine-grain (~100 nm) metal alloys from metal oxide nanoparticles. To demonstrate the process, an iron cobalt alloy (Fe_6_6Co_3_4) is obtained by hydrogen annealing 7-nm cobalt ferrite (CoFe_2O_4) nanoparticles in the presence of calcium granules. The calcium serves as a strong reducing agent, promoting the phase transition from cobalt ferrite to a metallic iron cobalt alloy, while maintaining high crystallinity. Magnetic measurements demonstrate the annealing temperature is the dominant factor of tuning the grain size and magnetic properties. Annealing at 700 °C for 1 h maximizes the magnetic saturation, up to 2.4 T (235 emu/g), which matches that of bulk iron cobalt.

Calcium-assisted reduction of cobalt ferrite nanoparticles for nanostructured iron cobalt with enhanced magnetic performance

Energy Technology Data Exchange (ETDEWEB)

Qi, B. [University of Florida, Interdisciplinary Microsystems Group, Department of Electrical and Computer Engineering (United States); Andrew, J. S. [University of Florida, Department of Materials Science and Engineering (United States); Arnold, D. P., E-mail: darnold@ufl.edu [University of Florida, Interdisciplinary Microsystems Group, Department of Electrical and Computer Engineering (United States)

2017-03-15

This paper demonstrates the potential of a calcium-assisted reduction process for synthesizing fine-grain (~100 nm) metal alloys from metal oxide nanoparticles. To demonstrate the process, an iron cobalt alloy (Fe{sub 66}Co{sub 34}) is obtained by hydrogen annealing 7-nm cobalt ferrite (CoFe{sub 2}O{sub 4}) nanoparticles in the presence of calcium granules. The calcium serves as a strong reducing agent, promoting the phase transition from cobalt ferrite to a metallic iron cobalt alloy, while maintaining high crystallinity. Magnetic measurements demonstrate the annealing temperature is the dominant factor of tuning the grain size and magnetic properties. Annealing at 700 °C for 1 h maximizes the magnetic saturation, up to 2.4 T (235 emu/g), which matches that of bulk iron cobalt.

Hybrid-secondary uncluttered permanent magnet machine and method

Science.gov (United States)

Hsu, John S.

2005-12-20

An electric machine (40) has a stator (43), a permanent magnet rotor (38) with permanent magnets (39) and a magnetic coupling uncluttered rotor (46) for inducing a slip energy current in secondary coils (47). A dc flux can be produced in the uncluttered rotor when the secondary coils are fed with dc currents. The magnetic coupling uncluttered rotor (46) has magnetic brushes (A, B, C, D) which couple flux in through the rotor (46) to the secondary coils (47c, 47d) without inducing a current in the rotor (46) and without coupling a stator rotational energy component to the secondary coils (47c, 47d). The machine can be operated as a motor or a generator in multi-phase or single-phase embodiments and is applicable to the hybrid electric vehicle. A method of providing a slip energy controller is also disclosed.

The magnetic properties of aligned M hexa-ferrite fibres

International Nuclear Information System (INIS)

Pullar, R.C.; Bhattacharya, A.K.

2006-01-01

Aligned and random fibres of strontium hexa ferrite (SrM, SrFe 12 O 19 ) and barium hexaferrite (BaM, BaFe 12 O 19 ) were manufactured by blow spinning from an aqueous inorganic sol-gel precursor, which was then fired to give the hexagonal ferrite fibre. Their magnetic properties were studied by VSM, investigating the evolution of these properties with firing and measurement temperature, and in particular the effects of fibre alignment. It has been predicted that aligned ferrite fibres will demonstrate an enhanced magnetisation along the axis of alignment with respect to perpendicular to the axis, and this has been demonstrated here for the first time. The optimum firing temperature was 1000 deg. C, at which point they still had submicron grains. In BaM random fibres M s =63.8 emu g -1 and H c =428.1 kA m -1 , and in SrM random fibres M s =63.3 emu g -1 and H c =452.8 kA m -1 , high values for polycrystalline materials. Fibres aligned parallel to the applied field had saturation magnetisation (M s ) values equal to those of the random fibres, whilst fibres aligned perpendicular to the field had M s values 62% and 75% lower, for BaM and SrM, respectively. There was no change in coercivity (H c ) between random or aligned fibres of any orientation, and fibres aligned 45 deg. and parallel to H appeared identical. Therefore, properties along the axis of alignment were superior when compared to measurements perpendicular to the axis of alignment, giving a directionality to the magnetisation in an otherwise randomly oriented ferrite material

Magnetic resonance elastometry using a single-sided permanent magnet

International Nuclear Information System (INIS)

Tan, Carl S; Marble, Andrew E; Ono, Yuu

2012-01-01

In this paper, we describe a magnetic resonance method of measuring material elasticity using a single-sided magnet with a permanent static field gradient. This method encodes sample velocity in a reciprocal space using Hahn spin-echoes with variable timing. The experimental results show a strong correlation between magnetic resonance signal attenuation and elasticity when an oscillating force is applied on the sample. This relationship in turn provides us with information about the displacement velocity experienced by the sample, which is inversely proportional to Young's modulus. The proposed method shows promise in offering a portable and cost-effective magnetic resonance elastography system. (paper)

Self-assembled organic-inorganic magnetic hybrid adsorbent ferrite based on cyclodextrin nanoparticles.

Science.gov (United States)

Denadai, Angelo M L; De Sousa, Frederico B; Passos, Joel J; Guatimosim, Fernando C; Barbosa, Kirla D; Burgos, Ana E; de Oliveira, Fernando Castro; da Silva, Jeann C; Neves, Bernardo R A; Mohallem, Nelcy D S; Sinisterra, Rubén D

2012-01-01

Organic-inorganic magnetic hybrid materials (MHMs) combine a nonmagnetic and a magnetic component by means of electrostatic interactions or covalent bonds, and notable features can be achieved. Herein, we describe an application of a self-assembled material based on ferrite associated with β-cyclodextrin (Fe-Ni/Zn/βCD) at the nanoscale level. This MHM and pure ferrite (Fe-Ni/Zn) were used as an adsorbent system for Cr(3+) and Cr(2)O(7) (2-) ions in aqueous solutions. Prior to the adsorption studies, both ferrites were characterized in order to determine the particle size distribution, morphology and available binding sites on the surface of the materials. Microscopy analysis demonstrated that both ferrites present two different size domains, at the micro- and nanoscale level, with the latter being able to self-assemble into larger particles. Fe-Ni/Zn/βCD presented smaller particles and a more homogeneous particle size distribution. Higher porosity for this MHM compared to Fe-Ni/Zn was observed by Brunauer-Emmett-Teller isotherms and positron-annihilation-lifetime spectroscopy. Based on the pKa values, potentiometric titrations demonstrated the presence of βCD in the inorganic matrix, indicating that the lamellar structures verified by transmission electronic microscopy can be associated with βCD assembled structures. Colloidal stability was inferred as a function of time at different pH values, indicating the sedimentation rate as a function of pH. Zeta potential measurements identified an amphoteric behavior for the Fe-Ni/Zn/βCD, suggesting its better capability to remove ions (cations and anions) from aqueous solutions compared to that of Fe-Ni/Zn.

Self-assembled organic–inorganic magnetic hybrid adsorbent ferrite based on cyclodextrin nanoparticles

Directory of Open Access Journals (Sweden)

Ângelo M. L. Denadai

2012-11-01

Full Text Available Organic–inorganic magnetic hybrid materials (MHMs combine a nonmagnetic and a magnetic component by means of electrostatic interactions or covalent bonds, and notable features can be achieved. Herein, we describe an application of a self-assembled material based on ferrite associated with β-cyclodextrin (Fe-Ni/Zn/βCD at the nanoscale level. This MHM and pure ferrite (Fe-Ni/Zn were used as an adsorbent system for Cr3+ and Cr2O72− ions in aqueous solutions. Prior to the adsorption studies, both ferrites were characterized in order to determine the particle size distribution, morphology and available binding sites on the surface of the materials. Microscopy analysis demonstrated that both ferrites present two different size domains, at the micro- and nanoscale level, with the latter being able to self-assemble into larger particles. Fe-Ni/Zn/βCD presented smaller particles and a more homogeneous particle size distribution. Higher porosity for this MHM compared to Fe-Ni/Zn was observed by Brunauer–Emmett–Teller isotherms and positron-annihilation-lifetime spectroscopy. Based on the pKa values, potentiometric titrations demonstrated the presence of βCD in the inorganic matrix, indicating that the lamellar structures verified by transmission electronic microscopy can be associated with βCD assembled structures. Colloidal stability was inferred as a function of time at different pH values, indicating the sedimentation rate as a function of pH. Zeta potential measurements identified an amphoteric behavior for the Fe-Ni/Zn/βCD, suggesting its better capability to remove ions (cations and anions from aqueous solutions compared to that of Fe-Ni/Zn.

Comparison between magnetic force microscopy and electron back-scatter diffraction for ferrite quantification in type 321 stainless steel

Energy Technology Data Exchange (ETDEWEB)

Warren, A.D., E-mail: Xander.Warren@bristol.ac.uk [Interface Analysis Centre, HH Wills Laboratory, University of Bristol, Bristol BS8 1FD (United Kingdom); Harniman, R.L. [School of Chemistry, University of Bristol, Bristol BS8 1 TS (United Kingdom); Collins, A.M. [School of Chemistry, University of Bristol, Bristol BS8 1 TS (United Kingdom); Bristol Centre for Functional Nanomaterials, Nanoscience and Quantum Information Centre, University of Bristol, Bristol BS8 1FD (United Kingdom); Davis, S.A. [School of Chemistry, University of Bristol, Bristol BS8 1 TS (United Kingdom); Younes, C.M. [Interface Analysis Centre, HH Wills Laboratory, University of Bristol, Bristol BS8 1FD (United Kingdom); Flewitt, P.E.J. [Interface Analysis Centre, HH Wills Laboratory, University of Bristol, Bristol BS8 1FD (United Kingdom); School of Physics, HH Wills Laboratory, University of Bristol, Bristol BS8 1FD (United Kingdom); Scott, T.B. [Interface Analysis Centre, HH Wills Laboratory, University of Bristol, Bristol BS8 1FD (United Kingdom)

2015-01-15

Several analytical techniques that are currently available can be used to determine the spatial distribution and amount of austenite, ferrite and precipitate phases in steels. The application of magnetic force microscopy, in particular, to study the local microstructure of stainless steels is beneficial due to the selectivity of this technique for detection of ferromagnetic phases. In the comparison of Magnetic Force Microscopy and Electron Back-Scatter Diffraction for the morphological mapping and quantification of ferrite, the degree of sub-surface measurement has been found to be critical. Through the use of surface shielding, it has been possible to show that Magnetic Force Microscopy has a measurement depth of 105–140 nm. A comparison of the two techniques together with the depth of measurement capabilities are discussed. - Highlights: • MFM used to map distribution and quantify ferrite in type 321 stainless steels. • MFM results compared with EBSD for same region, showing good spatial correlation. • MFM gives higher area fraction of ferrite than EBSD due to sub-surface measurement. • From controlled experiments MFM depth sensitivity measured from 105 to 140 nm. • A correction factor to calculate area fraction from MFM data is estimated.

Large polaron tunneling, magnetic and impedance analysis of magnesium ferrite nanocrystallite

Energy Technology Data Exchange (ETDEWEB)

Mahato, Dev K., E-mail: drdevkumar@yahoo.com [Department of Physics, National Institute of Technology Patna, Patna 800 005 (India); Majumder, Sumit [Department of Physics, Jadavpur University, Kolkata 700032 (India); Surface Physics and Material Science Division, Saha Institute of Nuclear Physics, 1/AF Bidhannagar, Kolkata 700 064 (India); Banerjee, S. [Surface Physics and Material Science Division, Saha Institute of Nuclear Physics, 1/AF Bidhannagar, Kolkata 700 064 (India)

2017-08-15

Graphical abstract: The diffraction peaks corresponding to the planes (111), (220), (311), (222), (400), (422), (511), (440), (620), (533) and (444) provide a clear evidence for the formation of spinel structure of the ferrites. The lattice parameter ‘a’ determined as 8.392 Å matches well with JCPDS (73-2410) file for MgFe{sub 2}O{sub 4.} The volume of the unit cell is 591.012 Å{sup 3}. The crystallite size of the synthesized powder estimated from X-ray peak broadening of (311) highest intensity diffraction peak using Scherer formula was 56.4 nm. - Highlights: • Both the grain and grain boundaries contribution to conductivity of the Mg-ferrite has been observed. • Polydispersive nature of the material is checked using Cole – Cole relation. • The ac conductivity of magnesium ferrite followed σ{sub ac} ∝ ω{sup n} dependence. • The variation of the exponent ‘n’ with temperature suggests that overlapping large polaron tunnelling is the dominant conduction mechanism. • The superparamagnetic behavior of this Mg-ferrite has been observed for sample S1 annealed at 500 °C. - Abstract: Single phase MgFe{sub 2}O{sub 4} (MFO) ferrite was prepared through sol-gel auto-combustion route. The Rietveld analysis of X-ray patterns reveals that our samples are single phase. The increase in average particle size with annealing temperature and formation of nanoparticle agglomerates is observed in MgFe{sub 2}O{sub 4}. The structural morphology of the nanoparticles is studied using Scanning Electron Microscopy (SEM). Formation of spinel structure is confirmed using Fourier transform infrared spectroscopy (FTIR). The Zero-Field-Cooled (ZFC) and Field-Cooled (FC) magnetization measurements show the maximum irreversibility at 700 °C annealing temperature. The formation of a maximum at blocking temperature, T{sub B}∼ 180 K for sample annealed at 500 °C in the ZFC curve shows the superparamagnetic behavior of the sample. The increase of saturation magnetism (M

Method and apparatus for assembling a permanent magnet pole assembly

Science.gov (United States)

Carl, Jr., Ralph James; Bagepalli, Bharat Sampathkumaran [Niskayuna, NY; Jansen, Patrick Lee [Scotia, NY; Dawson, Richard Nils [Voorheesville, NY; Qu, Ronghai [Clifton Park, NY; Avanesov, Mikhail Avramovich [Moscow, RU

2009-08-11

A pole assembly for a rotor, the pole assembly includes a permanent magnet pole including at least one permanent magnet block, a plurality of laminations including a pole cap mechanically coupled to the pole, and a plurality of laminations including a base plate mechanically coupled to the pole.

Permanent magnet material and process for producing the same

International Nuclear Information System (INIS)

Yoneyama, T.; Hori, T.; Ohima, T.

1978-01-01

This invention relates to an improvement of a permanent magnet material consisting, apart from impurities, of intermetallic compounds of the general formula of R 2 Co 17 , wherein the R component is at least one rare earth metal excluding radioactive elements and the Co component is cobalt. A suitable process to produce the permanent magnet material according to the invention is described. (U.K.)

The effect of Mg dopants on magnetic and structural properties of iron oxide and zinc ferrite thin films

Science.gov (United States)

Saritaş, Sevda; Ceviz Sakar, Betul; Kundakci, Mutlu; Yildirim, Muhammet

2018-06-01

Iron oxide thin films have been obtained significant interest as a material that put forwards applications in photovoltaics, gas sensors, biosensors, optoelectronic and especially in spintronics. Iron oxide is one of the considerable interest due to its chemical and thermal stability. Metallic ion dopant influenced superexchange interactions and thus changed the structural, electrical and magnetic properties of the thin film. Mg dopped zinc ferrite (Mg:ZnxFe3-xO4) crystal was used to avoid the damage of Fe3O4 (magnetite) crystal instead of Zn2+ in this study. Because the radius of the Mg2+ ion in the A-site (tetrahedral) is almost equal to that of the replaced Fe3+ ion. Inverse-spinel structure in which oxygen ions (O2-) are arranged to form a face-centered cubic (FCC) lattice where there are two kinds of sublattices, namely, A-site and B-site (octahedral) interstitial sites and in which the super exchange interactions occur. In this study, to increase the saturation of magnetization (Ms) value for iron oxide, inverse-spinal ferrite materials have been prepared, in which the iron oxide was doped by multifarious divalent metallic elements including Zn and Mg. Triple and quaternary; iron oxide and zinc ferrite thin films with Mg metal dopants were grown by using Spray Pyrolysis (SP) technique. The structural, electrical and magnetic properties of Mg dopped iron oxide (Fe2O3) and zinc ferrite (ZnxFe3-xO4) thin films have been investigated. Vibrating Sample Magnetometer (VSM) technique was used to study for the magnetic properties. As a result, we can say that Mg dopped iron oxide thin film has huge diamagnetic and of Mg dopped zinc ferrite thin film has paramagnetic property at bigger magnetic field.

Interfacial Phenomena of Magnetic Fluid with Permanent Magnet in a Longitudinally Excited Container

International Nuclear Information System (INIS)

Sudo, Seiichi; Wakuda, Hirofumi; Yano, Tetsuya

2008-01-01

This paper describes the magnetic fluid sloshing in a longitudinally excited container. Liquid responses of magnetic fluid with a permanent magnet in a circular cylindrical container subject to vertical vibration are investigated. Experiments are performed on a vibration- testing system which provided longitudinal excitation. A cylindrical container made with the acrylic plastic is used in the experiment. A permanent magnet is in the state of floating in a magnetic fluid. The disk-shaped and ring-shaped magnets are examined. The different interfacial phenomena from the usual longitudinal liquid sloshing are observed. It is found that the wave motion frequency of magnetic fluid with a disk-shaped magnet in the container subject to vertical vibration is exactly same that of the excitation. In the case of ring-shaped magnet, the first symmetrical mode of one-half subharmonic response is dominant at lower excitation frequencies. The magnetic fluid disintegration of the free surface was also observed by a high-speed video camera system

Interfacial Phenomena of Magnetic Fluid with Permanent Magnet in a Longitudinally Excited Container

Science.gov (United States)

Sudo, Seiichi; Wakuda, Hirofumi; Yano, Tetsuya

2008-02-01

This paper describes the magnetic fluid sloshing in a longitudinally excited container. Liquid responses of magnetic fluid with a permanent magnet in a circular cylindrical container subject to vertical vibration are investigated. Experiments are performed on a vibration- testing system which provided longitudinal excitation. A cylindrical container made with the acrylic plastic is used in the experiment. A permanent magnet is in the state of floating in a magnetic fluid. The disk-shaped and ring-shaped magnets are examined. The different interfacial phenomena from the usual longitudinal liquid sloshing are observed. It is found that the wave motion frequency of magnetic fluid with a disk-shaped magnet in the container subject to vertical vibration is exactly same that of the excitation. In the case of ring-shaped magnet, the first symmetrical mode of one-half subharmonic response is dominant at lower excitation frequencies. The magnetic fluid disintegration of the free surface was also observed by a high-speed video camera system.

Rotating permanent magnet excitation for blood flow measurement.

Science.gov (United States)

Nair, Sarath S; Vinodkumar, V; Sreedevi, V; Nagesh, D S

2015-11-01

A compact, portable and improved blood flow measurement system for an extracorporeal circuit having a rotating permanent magnetic excitation scheme is described in this paper. The system consists of a set of permanent magnets rotating near blood or any conductive fluid to create high-intensity alternating magnetic field in it and inducing a sinusoidal varying voltage across the column of fluid. The induced voltage signal is acquired, conditioned and processed to determine its flow rate. Performance analysis shows that a sensitivity of more than 250 mV/lpm can be obtained, which is more than five times higher than conventional flow measurement systems. Choice of rotating permanent magnet instead of an electromagnetic core generates alternate magnetic field of smooth sinusoidal nature which in turn reduces switching and interference noises. These results in reduction in complex electronic circuitry required for processing the signal to a great extent and enable the flow measuring device to be much less costlier, portable and light weight. The signal remains steady even with changes in environmental conditions and has an accuracy of greater than 95%. This paper also describes the construction details of the prototype, the factors affecting sensitivity and detailed performance analysis at various operating conditions.

Synthesis, structural, dielectric and magnetic properties of polyol assisted copper ferrite nano particles

Energy Technology Data Exchange (ETDEWEB)

Pavithradevi, S. [Assistant Professor, Department of Physics, Park College of Engineering and Technology, Coimbatore (India); Suriyanarayanan, N., E-mail: madurasuri2210@yahoo.com [Prof & Head, Department of Physics, Government College of Technology, Coimbatore (India); Boobalan, T. [Lecturer, Department of Physics, PSG Polytechnic College, Coimbatore (India)

2017-03-15

Nanocrystalline copper ferrite CuFe{sub 2}O{sub 4} is synthesized by co-precipitation method in ethylene glycol as chelating agent, using sodium Hydroxide as precipitator at pH 8. The as synthesized CuFe{sub 2}O{sub 4} is annealed at temperatures of 350 °C, 700 °C, and 1050 °C for 2 h respectively. The thermal analysis of the synthesized sample is done by TG technique. It is shown that at 260 °C ethylene glycol has evaporated completely and after 715 °C, spinel ferrite is formed with a cubic structure. The calculated lattice parameters are in agreement with the reported values. FTIR spectra of CuFe{sub 2}O{sub 4} nano particles are as synthesized and annealed at 1050 °C and recorded between 400 cm{sup −1} and 4000 cm{sup −1}. It shows that when the temperature increases ethylene glycol gradually evaporates. Finally, nano crystalline single phase spinel ferrite is obtained. X-ray diffraction (XRD) and electron diffraction (EDS) studies show that the sample is indexed as the face centered cubic spinel structure. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) indicated that the particles are flaky and spherical with the crystallite size in the range of 25–34 nm. From the dielectric studies, the dielectric constant decreases as the frequency increases. Low value of dielectric loss at higher frequencies suggests that the material is suitable for high frequency applications. AC conductivity increases with frequency. The magnetic properties of the samples are measured using a vibrating sample magnetometer (VSM) at room temperature, which shows that the sample exhibited a typical super paramagnetic behavior at low temperature. The saturation magnetization, remanant magnetism, and coercivity increases with applied field. - Highlights: • Complete removal of hematite phase along with ethylene glycol at 1050 °C. • Large decrease in particle sizes noticed along with ethylene glycol. • Ethylene glycol improves purity of the

Structural and magnetic studies of Cr doped nickel ferrite thin films

International Nuclear Information System (INIS)

Panwar, Kalpana; Heda, N. L.; Tiwari, Shailja; Bapna, Komal; Ahuja, B. L.; Choudhary, R. J.; Phase, D. M.

2016-01-01

We have studied the structural and magnetic properties of Cr doped nickel ferrite thin films deposited on Si (100) and Si (111) using pulsed laser deposition technique. The films were deposited under vacuum and substrate temperature was kept at 700°C. X-ray diffraction analysis revealed that films on both substrates have single phase cubic spinel structure. However, the film grown on Si (111) shows better crystalline behavior. Fourier transform infrared spectroscopy suggests that films on both substrates have mixed spinel structure. These films show magnetic hysteresis behavior and magnetization value of film on Si (100) is larger than that on Si (111). It turns out that structural and magnetic properties of these two films are correlated.

Making of Magnet Barium Ferit Anisotropic

International Nuclear Information System (INIS)

Idayati, Novrita; Dedi

2003-01-01

Barium Hexa ferrite (BaFe 12 O 19 ) is ceramic and materials which usually used for making of permanent magnet. In this research Barium Hexa ferrite were made Anisotropic, and applied for loudspeaker, electro motors, dynamo, KWh metre, etc. this Magnet is commonly used due to its high Induction of Remanen (Br) and coercivity (high Hc). Besides it applies a more simple and easier process technology, cheaper raw material, and easy to find it, hence the magnetic component is much cheaper. Powder Metallurgy was used for the process technology, by reacting all materials in the powder (oxide), with a certain size distribution and a tight preparation step. The next step was mixing ferrite and Barium Carbonate (in the form of oxide), calcination, compaction, cantering and characterisation. The Anisotropic particle effects a high Induce Remanen (Br) and of koersifitas (high Hc). All the process steps will is determine physical and chemical characteristics of the magnet. The best Magnet characteristic of the magnet produced in this research is Induction of Remanen (Br) = 4,27 kg, Coercivity (Hc) = 1,745 kOe, Energy Product max (BHmaks) = 2,31 MGOe

Influence of damping coefficient from permanent magnets on chatter formation during end milling of titanium alloy (Ti-6Al-4V)

International Nuclear Information System (INIS)

Sulaiman, S A; Amin, A N

2015-01-01

In machining operations, chatter is undesirable due to its adverse effects on the product quality, operation cost, machining accuracy and machine tool life. It is also responsible for reducing output. Chatter is a self-excitation phenomenon occurring in machine tools, in which the cutting process tends to lower the damping capacity of the machine structural components ending in an unstable behavior of the system. Chatter arises due to resonance when the vibrations of the instability of chip formation and the natural vibration modes of the machine-system components coincide. This paper focuses on the influence of damping coefficient from permanent magnets on chip serration frequency as an approach of minimizing chatter in end milling of Titanium alloy (Ti6Al4V). The method consists of two ferrite permanent magnet bars (dimensions: 1' × 6' × 3'), mounted 5mm from the cutting tool using a specially designed fixture which provided a uniform magnetic field of 2500-2700 Gausses. A titanium alloy Ti6Al4V block was then end milled using uncoated WC-Co inserts. A sequence of 15 experimental runs was conducted based on a small Central Composite Design (CCD) model in Response Surface Methodology (RSM). The primary (independent) parameters were: cutting speed, feed, and depth of cut. The data acquisition system comprised a vibration sensor (accelerometer) and a signal conditioning unit was used to measure the vibration data. The resultant vibrations were then analyzed using the DASYLab 5.6 software. Machining tests were conducted for two different conditions - with and without the application of magnets. Scanning Electron Microscope (SEM) was used to measure the chip segmentations. The SEM analysis of chip serrations demonstrated that the chip serration frequency were more stable while cutting under the presence of permanent magnets due to lower intensity of chatter. (paper)

Influence of damping coefficient from permanent magnets on chatter formation during end milling of titanium alloy (Ti-6Al-4V)

Science.gov (United States)

Sulaiman, S. A.; Amin, A. N.

2015-12-01

In machining operations, chatter is undesirable due to its adverse effects on the product quality, operation cost, machining accuracy and machine tool life. It is also responsible for reducing output. Chatter is a self-excitation phenomenon occurring in machine tools, in which the cutting process tends to lower the damping capacity of the machine structural components ending in an unstable behavior of the system. Chatter arises due to resonance when the vibrations of the instability of chip formation and the natural vibration modes of the machine-system components coincide. This paper focuses on the influence of damping coefficient from permanent magnets on chip serration frequency as an approach of minimizing chatter in end milling of Titanium alloy (Ti6Al4V). The method consists of two ferrite permanent magnet bars (dimensions: 1" × 6" × 3"), mounted 5mm from the cutting tool using a specially designed fixture which provided a uniform magnetic field of 2500-2700 Gausses. A titanium alloy Ti6Al4V block was then end milled using uncoated WC-Co inserts. A sequence of 15 experimental runs was conducted based on a small Central Composite Design (CCD) model in Response Surface Methodology (RSM). The primary (independent) parameters were: cutting speed, feed, and depth of cut. The data acquisition system comprised a vibration sensor (accelerometer) and a signal conditioning unit was used to measure the vibration data. The resultant vibrations were then analyzed using the DASYLab 5.6 software. Machining tests were conducted for two different conditions - with and without the application of magnets. Scanning Electron Microscope (SEM) was used to measure the chip segmentations. The SEM analysis of chip serrations demonstrated that the chip serration frequency were more stable while cutting under the presence of permanent magnets due to lower intensity of chatter.

Inversion degree and saturation magnetization of different nanocrystalline cobalt ferrites

International Nuclear Information System (INIS)

Concas, G.; Spano, G.; Cannas, C.; Musinu, A.; Peddis, D.; Piccaluga, G.

2009-01-01

The inversion degree of a series of nanocrystalline samples of CoFe 2 O 4 ferrites has been evaluated by a combined study, which exploits the saturation magnetization at 4.2 K and 57 Fe Moessbauer spectroscopy. The samples, prepared by sol-gel autocombustion, have different thermal history and particle size. The differences observed in the saturation magnetization of these samples are explained in terms of different inversion degrees, as confirmed by the analysis of the components in the Moessbauer spectra. It is notable that the inversion degrees of the samples investigated are set among the highest values reported in the literature.

Magnetic spectra and Richter aftereffect relaxation in Ce{sub x}Y{sub 3−x}Fe{sub 5}O{sub 12} ferrites

Energy Technology Data Exchange (ETDEWEB)

Chen, Fu; Wang, Xian; Feng, Zekun, E-mail: fengzekun@mail.hust.edu.cn [School of Optical and Electric Information, Huazhong University of Science and Technology, Wuhan, 430074 (China); Chen, Yajie; Harris, Vincent G. [Center for Microwave Magnetic Materials and Integrated Circuits, and Department of Electrical and Computer Engineering, Northeastern University, Boston, MA 02115 (United States)

2016-05-15

The static and dynamic magnetic properties of cerium (Ce) doped yttrium iron garnet Ce{sub x}Y{sub 3−x}Fe{sub 5}O{sub 12} (x=0, 0.05, 0.1, 0.15, 0.2) ferrites (YIG) have been reported in this work. The ferrites were fabricated by the traditional solid-state reaction method. All ferrite samples reveal pure garnet structure identified by x-ray diffraction (XRD). The substitution of cerium not only enhances the saturation magnetization of the samples, but also regulates the magnetocrystalline anisotropy constant K{sub 1}. Obvious differences in permeability spectra over a frequency of 1 MHz - 1 GHz can be observed. It is verified that the permeability dispersion and magnetic losses of Ce-doped YIG ferrite contain the contribution of Richter aftereffect relaxation due to the existence of Fe{sup 2+} ions. The fitting results of the permeability spectra applied three-mechanism model is in good agreement with experimental data, which successfully explains the mechanisms of magnetic losses observed at 1 MHz to 1 GHz for Ce-doped YIG ferrite. In addition, the frequency shift of Richter aftereffect has also been discussed.

Magnetic loss analysis in Mn-Zn ferrite cores

International Nuclear Information System (INIS)

Beatrice, C.; Bottauscio, O.; Chiampi, M.; Fiorillo, F.; Manzin, A.

2006-01-01

Magnetic losses have been measured and analyzed upon a wide range of frequencies in Mn-Zn ferrite ring cores. Exploiting the concept of loss separation and modeling the conductivity process in the heterogeneous material as a function of frequency, the role of the different energy dissipation mechanisms has been elucidated. It is shown, in particular, that eddy current effects can be appreciated, in standard materials and cores, only on approaching and overcoming the MHz range. The basic mechanism for hysteresis and low-frequency losses is therefore identified with the domain wall relaxation engendered by spin damping processes. Resonant absorption of energy associated with magnetization rotation is in turn deemed to chiefly contribute to the loss upon the practical range of frequencies going from a few 10 4 Hz to a few MHz

Study of magnetic and structural properties of ferrofluids based on cobalt-zinc ferrite nanoparticles

International Nuclear Information System (INIS)

Lopez, J.; Gonzalez-Bahamon, L.F.; Prado, J.; Caicedo, J.C.; Zambrano, G.; Gomez, M.E.; Esteve, J.; Prieto, P.

2012-01-01

Ferrofluids are colloidal systems composed of a single domain of magnetic nanoparticles with a mean diameter around 30 nm, dispersed in a liquid carrier. Magnetic Co (1-x) Zn x Fe 2 O 4 (x=0.25, 0.50, 0.75) ferrite nanoparticles were prepared via co-precipitation method from aqueous salt solutions in an alkaline medium. The composition and structure of the samples were characterized through Energy Dispersive X-ray Spectroscopy and X-ray diffraction, respectively. Transmission Electron Microscopy (TEM) studies permitted determining nanoparticle size; grain size of nanoparticle conglomerates was established via Atomic Force Microscopy. The magnetic behavior of ferrofluids was characterized by Vibrating Sample Magnetometer (VSM); and finally, a magnetic force microscope was used to visualize the magnetic domains of Co (1-x) Zn x Fe 2 O 4 nanoparticles. X-ray diffraction patterns of Co (1-x) Zn x Fe 2 O 4 show the presence of the most intense peak corresponding to the (311) crystallographic orientation of the spinel phase of CoFe 2 O 4 . Fourier Transform Infrared Spectroscopy confirmed the presence of the bonds associated to the spinel structures; particularly for ferrites. The mean size of the crystallite of nanoparticles determined from the full-width at half maximum of the strongest reflection of the (311) peak by using the Scherrer approximation diminished from (9.5±0.3) nm to (5.4±0.2) nm when the Zn concentration increases from 0.21 to 0.75. The size of the Co-Zn ferrite nanoparticles obtained by TEM is in good agreement with the crystallite size calculated from X-ray diffraction patterns, using Scherer's formula. The magnetic properties investigated with the aid of a VSM at room temperature presented super-paramagnetic behavior, determined by the shape of the hysteresis loop. In this study, we established that the coercive field of Co (1-x) Zn x Fe 2 O 4 magnetic nanoparticles, the crystal and nanoparticle sizes determined by X-ray Diffraction and TEM

Sensorless Control of Permanent Magnet Synchronous Machines

DEFF Research Database (Denmark)

Matzen, Torben N.

Permanent magnet machines, with either surface mounted or embedded magnets on the rotor, are becoming more common due to the key advantages of higher energy conversion efficiency and higher torque density compared to the classical induction machine. Besides energy efficiency the permanent magnet...... the synchronous machine requires knowledge of the rotor shaft position due to the synchronous and undamped nature of the machine. The rotor position may be measured using a mechanical sensor, but the sensor reduces reliability and adds cost to the system and for this reason sensorless control methods started...... are dependent on the phase currents and rotor position. Based on the flux linkages the differential inductances are determined and used to establish the inductance saliency in terms of ratio and orientation. The orientation and its dependence on the current and rotor position are used to analyse the behaviour...

Tunable bandpass filter based on partially magnetized ferrite LTCC with embedded windings for SoP applications

KAUST Repository

Arabi, Eyad A.; Ghaffar, Farhan A.; Shamim, Atif

2015-01-01

to the previously reported filters. A simulation strategy that uses full permeability tensor with arbitrarily directed magnetic fields has been used to model the filter on a partially magnetized ferrite substrate. Special attention has also been paid to approximate

Effect of Powder Grain Size on Microstructure and Magnetic Properties of Hexagonal Barium Ferrite Ceramic

Science.gov (United States)

Shao, Li-Huan; Shen, Si-Yun; Zheng, Hui; Zheng, Peng; Wu, Qiong; Zheng, Liang

2018-05-01

Compact hexagonal barium ferrite (BaFe12O19, BaM) ceramics with excellent magnetic properties have been prepared from powder with the optimal grain size. The dependence of the microstructure and magnetic properties of the ceramics on powder grain size was studied in detail. Single-phase hexagonal barium ferrite powder with grain size of 177 nm, 256 nm, 327 nm, and 454 nm was obtained by calcination under different conditions. Scanning electron microscopy revealed that 327-nm powder was beneficial for obtaining homogeneous grain size and compact ceramic. In addition, magnetic hysteresis loops and complex permeability spectra demonstrated that the highest saturation magnetization (67.2 emu/g) and real part of the permeability (1.11) at 1 GHz were also obtained using powder with grain size of 327 nm. This relationship between the powder grain size and the properties of the resulting BaM ceramic could be significant for development of microwave devices.

Magnetic Field Emissions for Ferrite and Non-Ferrite Geometries for Wireless Power Transfer to Vehicles

DEFF Research Database (Denmark)

Batra, Tushar; Schaltz, Erik

2014-01-01

Minimizing magnetic field emissions to surroundings is one of the most challenging design criteria for wireless power transfer to vehicles. In this paper, concept of division of the emissions into three zones (primary, secondary, and combined zone) in the vertical direction is introduced. For geo......Minimizing magnetic field emissions to surroundings is one of the most challenging design criteria for wireless power transfer to vehicles. In this paper, concept of division of the emissions into three zones (primary, secondary, and combined zone) in the vertical direction is introduced...... for vertical separation between the coils in range of 100-180 mm. It is observed that lower vertical separation results in higher overlapping of the zones and the coils behave as they are effectively placed close to center of air gap. The analysis in this work provides a better understanding of the space...... profile of magnetic field emissions (with and without ferrite) for wireless power transfer to vehicles....

Exterior rotor permanent magnet generator in variable speed applications

OpenAIRE

Sattar, Rauf

2016-01-01

This thesis explores approaches for converting rotational mechanical power from diesel engines into electrical power of fixed frequency and voltage. Advances in high energy permanent magnets and power electronics are enabling technologies that provide opportunities for electrical machines with increased efficiency and compact size for variable speed power generation. The overall objective was to design a permanent magnet machine with concentrated winding that could be used in variable spe...

Design and analysis of tubular permanent magnet linear wave generator.

Science.gov (United States)

Si, Jikai; Feng, Haichao; Su, Peng; Zhang, Lufeng

2014-01-01

Due to the lack of mature design program for the tubular permanent magnet linear wave generator (TPMLWG) and poor sinusoidal characteristics of the air gap flux density for the traditional surface-mounted TPMLWG, a design method and a new secondary structure of TPMLWG are proposed. An equivalent mathematical model of TPMLWG is established to adopt the transformation relationship between the linear velocity of permanent magnet rotary generator and the operating speed of TPMLWG, to determine the structure parameters of the TPMLWG. The new secondary structure of the TPMLWG contains surface-mounted permanent magnets and the interior permanent magnets, which form a series-parallel hybrid magnetic circuit, and their reasonable structure parameters are designed to get the optimum pole-arc coefficient. The electromagnetic field and temperature field of TPMLWG are analyzed using finite element method. It can be included that the sinusoidal characteristics of air gap flux density of the new secondary structure TPMLWG are improved, the cogging force as well as mechanical vibration is reduced in the process of operation, and the stable temperature rise of generator meets the design requirements when adopting the new secondary structure of the TPMLWG.

Design and Analysis of Tubular Permanent Magnet Linear Wave Generator

Directory of Open Access Journals (Sweden)

Jikai Si

2014-01-01

Full Text Available Due to the lack of mature design program for the tubular permanent magnet linear wave generator (TPMLWG and poor sinusoidal characteristics of the air gap flux density for the traditional surface-mounted TPMLWG, a design method and a new secondary structure of TPMLWG are proposed. An equivalent mathematical model of TPMLWG is established to adopt the transformation relationship between the linear velocity of permanent magnet rotary generator and the operating speed of TPMLWG, to determine the structure parameters of the TPMLWG. The new secondary structure of the TPMLWG contains surface-mounted permanent magnets and the interior permanent magnets, which form a series-parallel hybrid magnetic circuit, and their reasonable structure parameters are designed to get the optimum pole-arc coefficient. The electromagnetic field and temperature field of TPMLWG are analyzed using finite element method. It can be included that the sinusoidal characteristics of air gap flux density of the new secondary structure TPMLWG are improved, the cogging force as well as mechanical vibration is reduced in the process of operation, and the stable temperature rise of generator meets the design requirements when adopting the new secondary structure of the TPMLWG.

Design and Analysis of Tubular Permanent Magnet Linear Wave Generator

Science.gov (United States)

Si, Jikai; Feng, Haichao; Su, Peng; Zhang, Lufeng

2014-01-01

Due to the lack of mature design program for the tubular permanent magnet linear wave generator (TPMLWG) and poor sinusoidal characteristics of the air gap flux density for the traditional surface-mounted TPMLWG, a design method and a new secondary structure of TPMLWG are proposed. An equivalent mathematical model of TPMLWG is established to adopt the transformation relationship between the linear velocity of permanent magnet rotary generator and the operating speed of TPMLWG, to determine the structure parameters of the TPMLWG. The new secondary structure of the TPMLWG contains surface-mounted permanent magnets and the interior permanent magnets, which form a series-parallel hybrid magnetic circuit, and their reasonable structure parameters are designed to get the optimum pole-arc coefficient. The electromagnetic field and temperature field of TPMLWG are analyzed using finite element method. It can be included that the sinusoidal characteristics of air gap flux density of the new secondary structure TPMLWG are improved, the cogging force as well as mechanical vibration is reduced in the process of operation, and the stable temperature rise of generator meets the design requirements when adopting the new secondary structure of the TPMLWG. PMID:25050388

Synthesis of ferrofluids based on cobalt ferrite nanoparticles: Influence of reaction time on structural, morphological and magnetic properties

Energy Technology Data Exchange (ETDEWEB)

Amirabadizadeh, Ahmad; Salighe, Zohre; Sarhaddi, Reza, E-mail: reza.sarhaddi@birjand.ac.ir; Lotfollahi, Zahra

2017-07-15

Highlights: • Ferrofluids based on cobalt ferrite nanoparticles were synthesized by co-precipitation method. • The crystallite and particle size of cobalt ferrite can be controlled effectively by reaction time. • The ferrofluids have lower values of saturation magnetization and coercivity as compared to nanoparticles. • By increasing the size of nanoparticles, the narrower and sharper spikes of ferrofluids are formed. - Abstract: In this work, for first time the ferrofluids based on the cobalt ferrite (CoFe{sub 2}O{sub 4}) nanoparticles were prepared by the co-precipitation method at different reaction times (0.5–6.5 h). Crystal structure, morphology and magnetic properties of the cobalt ferrite nanoparticles and the ferrofluids based on the nanoparticles were studied by X-ray diffraction (XRD), field emission scanning electron microscope (FESEM) and vibrating sample magnetometer (VSM). The XRD patterns of CoFe{sub 2}O{sub 4} nanoparticles synthesized at different reaction times indicated that all samples are single phase in accordance with inverse cubic spinel structure with space group Fd-3m, and no impurity phase was observed. By increasing the reaction time to 3.5 h, the lattice parameter and the average crystallites size increased and then afterwards decreased by increasing the reaction time. The microscopic studies indicated the formation of nanosized particles with nearly spherical in shape, whereas the average particle size for all samples is found to be less than 50 nm. The results of VSM also showed that the saturation magnetization and coercivity field of the cobalt ferrite nanoparticles and the ferrofluids were influenced by reaction time, whereas the ferrofluids have lower values of magnetic parameters than that of nanoparticles.

Design Considerations of Permanent Magnet Transverse Flux Machines

DEFF Research Database (Denmark)

Lu, Kaiyuan; Rasmussen, Peter Omand; Ritchie, Ewen

2011-01-01

electrical machines. This paper addresses two important design considerations for PMTFM—the influence of permanent magnet leakage flux, which plays an important role in the determination of machine output torque, and the leakage inductance. A new simple method to provide a quick estimation of the armature......Permanent magnet transverse flux machine (PMTFM) is well known for its high torque density and is interested in various direct-drive applications. Due to its complicated 3-D flux components, design and design optimization of a PMTFM is more difficult and time consuming than for radial flux...

2D Analytical Modeling of Magnetic Vector Potential in Surface Mounted and Surface Inset Permanent Magnet Machines

Directory of Open Access Journals (Sweden)

A. Jabbari

2017-12-01

Full Text Available A 2D analytical method for magnetic vector potential calculation in inner rotor surface mounted and surface inset permanent magnet machines considering slotting effects, magnetization orientation and winding layout has been proposed in this paper. The analytical method is based on the resolution of Laplace and Poisson equations as well as Maxwell equation in quasi- Cartesian coordinate by using sub-domain method and hyperbolic functions. The developed method is applied on the performance computation of two prototypes surface mounted permanent magnet motors and two prototypes surface inset permanent magnet motors. A radial and a parallel magnetization orientation is considered for each type of motor. The results of these models are validated through FEM method.

[Development of RF coil of permanent magnet mini-magnetic resonance imager and mouse imaging experiments].

Science.gov (United States)

Hou, Shulian; Xie, Huantong; Chen, Wei; Wang, Guangxin; Zhao, Qiang; Li, Shiyu

2014-10-01

In the development of radio frequency (RF) coils for better quality of the mini-type permanent magnetic resonance imager for using in the small animal imaging, the solenoid RF coil has a special advantage for permanent magnetic system based on analyses of various types.of RF coils. However, it is not satisfied for imaging if the RF coils are directly used. By theoretical analyses of the magnetic field properties produced from the solenoid coil, the research direction was determined by careful studies to raise further the uniformity of the magnetic field coil, receiving coil sensitivity for signals and signal-to-noise ratio (SNR). The method had certain advantages and avoided some shortcomings of the other different coil types, such as, birdcage coil, saddle shaped coil and phased array coil by using the alloy materials (from our own patent). The RF coils were designed, developed and made for keeled applicable to permanent magnet-type magnetic resonance imager, multi-coil combination-type, single-channel overall RF receiving coil, and applied for a patent. Mounted on three instruments (25 mm aperture, with main magnetic field strength of 0.5 T or 1.5 T, and 50 mm aperture, with main magnetic field strength of 0.48 T), we performed experiments with mice, rats, and nude mice bearing tumors. The experimental results indicated that the RF receiving coil was fully applicable to the permanent magnet-type imaging system.

Effect of Synthesis Parameters on the Structure and Magnetic Properties of Magnetic Manganese Ferrite/Silver Composite Nanoparticles Synthesized by Wet Chemistry Method

DEFF Research Database (Denmark)

Huy, L.T.; Tam, L.T.; Phan, V.N.

2016-01-01

In the present work, magnetic manganese ferrite/silver (MnFe2O4-Ag) composite nanoparticles were synthesized by wet chemistry method. This synthesis process consists of two steps: first, the seed of manganese ferrite nanoparticles (MnFe2O4 NPs) was prepared by a coprecipitationmethod; second......, growth of silver nanoparticles (AgNPs) on the MnFe2O4 seed by modified photochemical reaction. We have conducted systematically the effects of synthesis parameters such as pH value, synthesis time, precursor salts concentration, mass ratio and stabilizing agents on the structure and magnetic properties......-prepared MnFe2O4-Ag magnetic nanocomposites display excellent properties of high crystallinity, long-term aggregation stability in aqueous medium, large saturation magnetization in the range of 15-20 emu/g, and small sizes of Ag-NPs similar to 20 nm. These exhibited properties made the MnFe2O4-Ag...

Design improvement of permanent magnet flux switching motor with dual rotor structure

Science.gov (United States)

Soomro, H. A.; Sulaiman, E.; Kumar, R.; Rahim, N. S.

2017-08-01

This paper presents design enhancement to reduce permanent magnet (PM) volume for 7S-6P-7S dual rotor permanent magnet flux-switching machines (DRPMFSM) for electric vehicle application. In recent years, Permanent magnet flux switching (PMFS) motor and a new member of brushless permanent magnet machine are prominently used for the electric vehicle. Though, more volume of Rare-Earth Permanent Magnet (REPM) is used to increase the cost and weight of these motors. Thus, to overcome the issue, new configuration of 7S-6P- 7S dual rotor permanent magnet flux-switching machine (DRPMFSM) has been proposed and investigated in this paper. Initially proposed 7S-6P-7S DRPMFSM has been optimized using “deterministic optimization” to reduce the volume of PM and to attain optimum performances. In addition, the performances of initial and optimized DRPMFSM have been compared such that back-emf, cogging torque, average torque, torque and power vs speed performances, losses and efficiency have been analysed by 2D-finite element analysis (FEA) using the JMAG- Designer software ver. 14.1. Consequently, the final design 7S-6P-7S DRPMFSM has achieved the efficiency of 83.91% at reduced PM volume than initial design to confirm the better efficient motor for HEVs applications.

Influence of cold isostatic pressing on the magnetic properties of Ni-Zn-Cu ferrite

Directory of Open Access Journals (Sweden)

Trong Trung Le

2018-04-01

Full Text Available In power electronics, there is the need to develop solutions to increase the power density of converters. Interleaved multicellular transformers allow interleaving many switching cells and, as a result, a possible increase in the power density. This converter is often composed of a magnetic core having the function of an intercell transformer (ICT and, depending on the complexity of the designed architecture, its shape could be extremely complex. The switching frequencies (1-10 MHz for the new wide band gap semiconductors (SiC, GaN allow to interleave switching cell at higher frequencies than silicon-based semiconductors (<1 MHz. Intercell transformers must follow this increase in frequency times-fold the number of switching cells. Current applications for ICT transformers use Mn-Zn based materials, but their limit in frequency drive raises the need of higher frequency magnetic materials, such Ni-Zn ferrites. These materials can operate in medium and high power converters up to 10 MHz. We propose to use Ni0,30Zn0,57Cu0,15Fe2O4 ferrite and to compress it by cold isostatic pressing (CIP into a a green ceramic block and to machine it to obtain the desired ICT of complex shape prior sintering. We compare the magnetic permeability spectra and hysteresis loops the CIP and uniaxially pressed ferrites. The effect of temperature and sintering time as well as high-pressure on properties will be presented in detail. The magnetic properties of the sintered cores are strongly dependent on the microstructure obtained.

Design considerations for permanent magnet direct drive generators for wind energy applications

NARCIS (Netherlands)

Jassal, A.K.; Polinder, H.; Damen, M.E.C.; Versteegh, K.

2012-01-01

Permanent Magnet Direct Drive (PMDD) generators offer very high force density, high efficiency and low number of components. Due to these advantages, PMDD generators are getting popular in the wind energy industry especially for offshore application. Presence of permanent magnets gives magnetic

Magnetization, magnetic susceptibility, effective magnetic moment of Fe3+ ions in Bi25FeO39 ferrite

International Nuclear Information System (INIS)

Zatsiupa, A.A.; Bashkirov, L.A.; Troyanchuk, I.O.; Petrov, G.S.; Galyas, A.I.; Lobanovsky, L.S.; Truhanov, S.V.

2014-01-01

Magnetic susceptibility for ferrite Bi 25 FeO 39 is measured at 5–950 K in the magnetic field of 0.86 T. It is shown that Bi 25 FeO 39 is paramagnetic in the temperature range 5−950 K. The saturation magnetization is equal to 5.04μ B per formula unit at 5 K in a magnetic field of 10 T. It is found that at 5−300 K the effective magnetic moment of Fe 3+ ions in Bi 25 FeO 39 is equal to 5.82μ B . - Graphical abstract: The dependence of the magnetization (n, μ B ) on the magnetic field for one formula unit of Bi 25 FeO 39 at 5 K. - Highlights: • Magnetic susceptibility for Bi 25 FeO 39 is measured at 5–950 K in the magnetic field of 0.86 T. • It is shown that Bi 25 FeO 39 is paramagnetic in the temperature range 5−950 K. • The saturation magnetization is equal to 5.04μ B per formula unit at 5 K in a magnetic field of 10 T

Tunable high-gradient permanent magnet quadrupoles

CERN Document Server

Shepherd, B J A; Marks, N; Collomb, N A; Stokes, D G; Modena, M; Struik, M; Bartalesi, A

2014-01-01

A novel type of highly tunable permanent magnet (PM) based quadrupole has been designed by the ZEPTO collaboration. A prototype of the design (ZEPTO-Q1), intended to match the specification for the CLIC Drive Beam Decelerator, was built and magnetically measured at Daresbury Laboratory and CERN. The prototype utilises two pairs of PMs which move in opposite directions along a single vertical axis to produce a quadrupole gradient variable between 15 and 60 T/m. The prototype meets CLIC's challenging specification in terms of the strength and tunability of the magnet.

Permanent-magnet-less synchronous reluctance system

Science.gov (United States)

Hsu, John S

2012-09-11

A permanent magnet-less synchronous system includes a stator that generates a magnetic revolving field when sourced by an alternating current. An uncluttered rotor is disposed within the magnetic revolving field and spaced apart from the stator to form an air gap relative to an axis of rotation. The rotor includes a plurality of rotor pole stacks having an inner periphery biased by single polarity of a north-pole field and a south-pole field, respectively. The outer periphery of each of the rotor pole stacks are biased by an alternating polarity.

Structural, Magnetic and Microwave Properties of Nanocrystalline Ni-Co-Gd Ferrites

Science.gov (United States)

Nikzad, Alireza; Parvizi, Roghaieh; Rezaei, Ghasem; Vaseghi, Behrooz; Khordad, Reza

2018-02-01

A series of Co- and Gd-substituted NiFe2O4 ferrite nanoparticles with the formula Ni1- x Co x Fe2- y Gd y O4 (where x = 0.0-1.0 and y = 0.0-0.1) have been successfully synthesized using a hydrothermal method. X-ray diffraction and field emission scanning electron microscopy results indicated that a highly crystallized spherical ferrite nanoparticle structure was obtained along with an increase in the lattice parameters. Compositional analysis of the prepared nanoferrite powders has been carried out using energy-dispersive x-ray (EDX) spectra. The EDX analysis reveals the presence of Ni, Co, Gd and Fe elements in the specimens. Magnetization and the coercive field improved dramatically with an increase in the amount of cobalt and gadolinium added, attributed to the redistribution of cations in the spinel nanoferrite structure. Saturation magnetization and coercivity values up to 99 emu/g and 918 Oe, respectively, were measured using a vibration sample magnetometer at room temperature. Comparative microwave absorption experiments demonstrated that the reflection loss (RL) properties enhanced with increasing substitution of cations in the Ni-ferrite spinel structure for an absorber thickness of 1.8 mm. A maximum RL of - 26.7 dB was obtained for substituted Ni-Co-Gd nanoferrite with x = 1.0 and y = 0.1 at a frequency of 9.4 GHz with a bandwidth of 3.6 GHz (RL ≤ - 10 dB). Experimental results revealed that the synthesized nanoparticles possessed great potential in microwave absorption applications.

Investigations on microstructure, electrical and magnetic properties of copper spinel ferrite with WO3 addition for applications in the humidity sensors

Science.gov (United States)

Tudorache, Florin

2018-04-01

In the present study we report the structural, electrical, magnetic and humidity characteristics of copper ferrite with different percent on tungsten trioxide addition. The aim of this study was to obtain more stable and sensitive active materials for humidity sensors. In order to highlight the influence of tungsten on the structural, electrical and magnetic properties, the ferrite samples were fabricated via sol-gel self-combustion method and sintered for 30 min at 1000 °C with percent between 0 and 20% tungsten trioxide additions. The X-ray diffraction investigations showed the copper ferrite phase composition. The scanning electron microscopy revealed the influence of the substitution on characteristics of the crystallites and the profilometry showed the surface topography of samples. The investigation was focused on the variation of permittivity and electrical conductivity, in relation with tungsten trioxide addition, frequency and humidity. We have also, investigated the relevant magnetic characteristics of the copper ferrite material by highlighting the influence of tungsten trioxide addition on to Curie temperature and the permeability frequency characteristics. The data suggests that the copper ferrite with tungsten trioxide addition can be used as active material for humidity sensors.

Tuning permanent magnets with adjustable field clamps

International Nuclear Information System (INIS)

Schermer, R.I.

1987-01-01

The effective length of a permanent-magnet assembly can be varied by adjusting the geometrical parameters of a field clamp. This paper presents measurements on a representative dipole and quadrupole as the field clamp is withdrawn axially or radially. The detailed behavior depends upon the magnet multipolarity and geometry. As a rule-of-thumb, a 3-mm-thick iron plate placed at one end plane of the magnet will shorten the length by one-third of the magnet bore radius

Constant force linear permanent magnet actuators

NARCIS (Netherlands)

Paulides, J.J.H.; Encica, L.; Meessen, K.J.; Lomonova, E.A.

2009-01-01

In applications, such as vibration isolation, gravity compensation, pick-and-place machines, etc., there is a need for (long-stroke) passive constant force actuators combined with tubular permanent magnet actuators to minimize the power consumption, hence, passively counteract the gravitational

Synthesis, structural investigation and magnetic properties of Zn2+ substituted cobalt ferrite nanoparticles prepared by the sol–gel auto-combustion technique

International Nuclear Information System (INIS)

Raut, A.V.; Barkule, R.S.; Shengule, D.R.; Jadhav, K.M.

2014-01-01

Structural morphology and magnetic properties of the Co 1−x Zn x Fe 2 O 4 (0.0≤x≥1.0) spinel ferrite system synthesized by the sol–gel auto-combustion technique using nitrates of respective metal ions have been studied. The ratio of metal nitrates to citric acid was taken at 1:3. The as prepared powder of cobalt zinc ferrite was sintered at 600 °C for 12 h after TG/DTA thermal studies. Compositional stoichiometry was confirmed by energy dispersive analysis of the X-ray (EDAX) technique. Single phase cubic spinel structure of Co–Zn nanoparticles was confirmed by XRD data. The average crystallite size (t), lattice constant (a) and other structural parameters of zinc substituted cobalt ferrite nanoparticles were calculated from XRD followed by SEM and FTIR. It is observed that the sol–gel auto-combustion technique has many advantages for the synthesis of technologically applicable Co–Zn ferrite nanoparticles. The present investigation clearly shows the effect of the synthesis method and possible relation between magnetic properties and microstructure of the prepared samples. Increase in nonmagnetic Zn 2+ content in cobalt ferrite nanoparticles is followed by decrease in n B , M s and other magnetic parameters. Squareness ratio for the Co-ferrite was 1.096 at room temperature. - Highlights: • Co–Zn nanoparticles are prepared by sol–gel auto-combustion method. • Structural properties were characterized by XRD, SEM, and FTIR. • Compositional stoichiometry was confirmed by EDAX analysis. • Magnetic parameters were measured by the pulse field hysteresis loop technique

Fixed-Time Stability Analysis of Permanent Magnet Synchronous Motors with Novel Adaptive Control

Directory of Open Access Journals (Sweden)

Maoxing Liu

2017-01-01

Full Text Available We firstly investigate the fixed-time stability analysis of uncertain permanent magnet synchronous motors with novel control. Compared with finite-time stability where the convergence rate relies on the initial permanent magnet synchronous motors state, the settling time of fixed-time stability can be adjusted to desired values regardless of initial conditions. Novel adaptive stability control strategy for the permanent magnet synchronous motors is proposed, with which we can stabilize permanent magnet synchronous motors within fixed time based on the Lyapunov stability theory. Finally, some simulation and comparison results are given to illustrate the validity of the theoretical results.

Irradiation of Nd-Fe-B permanent magnets with APS bending magnet x-rays and 60Co γ-rays

International Nuclear Information System (INIS)

Alderman, J.; Job, P. K.; Puhl, J.

2000-01-01

The Advanced Photon Source (APS), as well as other third-generation synchrotron light sources, uses permanent magnets in the insertion devices to produce x-rays for scientific research. When placed in a high-energy storage ring, these permanent magnets are subjected to irradiation from synchrotron radiation, high-energy bremsstrahlung, and bremsstrahlung-produced photoneutrons. Previous investigations have exhibited varying degrees of degradation in the intensity of magnetization of these magnets due to irradiation from electron beams, 60 Co γrays, and high-energy neutrons. The APS specifically uses Nd-Fe-B permanent magnets in their insertion devices. Although no detectable radiation-induced demagnetization has been observed in the APS insertion devices so far, partial demagnetization has been observed in at least one insertion device at the European Synchrotron Radiation Facility (ESRF), where Nd-Fe-B permanent magnets are also used

Preparation of Mn-Zn ferrite nanoparticles and their silica-coated clusters: magnetic properties and transverse relaxivity

Czech Academy of Sciences Publication Activity Database

Kaman, Ondřej; Kuličková, Jarmila; Herynek, Vít; Koktan, Jakub; Maryško, Miroslav; Dědourková, T.; Knížek, Karel; Jirák, Zdeněk

2017-01-01

Roč. 427, Apr (2017), s. 251-257 ISSN 0304-8853 Institutional support: RVO:68378271 ; RVO:68378041 Keywords : magnetic nanoparticles * Mn-Zn ferrite * hydrothermal synthesis * magnetic resonance imaging * transverse relaxivity Subject RIV: BM - Solid Matter Physics ; Magnetism OBOR OECD: Condensed matter physics (including formerly solid state physics, supercond.) Impact factor: 2.630, year: 2016

The Permanent Magnet Operating Mechanism of Double Coil Parallel Driven at a High Speed

Directory of Open Access Journals (Sweden)

WEI Xau-Lao

2017-02-01

Full Text Available Abstract:Operating mechanism is the main part of breaker，and the quality of breaker will directly influence the safe operation of power system. Because of the continuous improvement requirements of switch，in order to mak this actuator faster and more powerful closing，this paper proposes a double coil parallel driven permanent magnet actuator at a high speed. This paper expounds the working principle of single and double coil parallel driven permanent magnet actuator. It uses Ansoft building model and contrasts test results. In prance we designed and produced the single and double coil parallel driven permanent magnet actuator for experimental study. The simulation and experiment results show that double coil parallel driven permanent magnet actuator，compared with single coil parallel driven permanent magnet actuator，has a better and faster action performance. Thus，the double coil parallel driven permanent magnet actuator achieves a kind of optimization.

Experiences with permanent magnets at the Fermilab recycler ring

International Nuclear Information System (INIS)

Volk, James T

2011-01-01

In order to achieve higher luminosities in Run II a separate antiproton storage ring was built in the Main Injector tunnel. To reduce both construction and operations costs permanent magnets were used. This paper discusses the design criterion and specifications, including temperature dependence, longitudinal uniformity, and adjusting of the higher harmonics of the magnets. The design tolerances for a storage ring are more stringent than for a single pass beam line. The difference between the measured and ideal central field for each magnet was held to better than 0.1%. The temperature stability for all magnets was set to better than 0.01% per degree Celsius. Higher order harmonics relative to the central field were set to less than 0.01%. This was done for all 484 permanent magnet that were built.

Magnetization reversal processes of isotropic permanent magnets with various inter-grain exchange interactions

Directory of Open Access Journals (Sweden)

Hiroshi Tsukahara

2017-05-01

Full Text Available We performed a large-scale micromagnetics simulation on a supercomputing system to investigate the properties of isotropic nanocrystalline permanent magnets consisting of cubic grains. In the simulation, we solved the Landau–Lifshitz–Gilbert equation under a periodic boundary condition for accurate calculation of the magnetization dynamics inside the nanocrystalline isotropic magnet. We reduced the inter-grain exchange interaction perpendicular and parallel to the external field independently. Propagation of the magnetization reversal process is inhibited by reducing the inter-grain exchange interaction perpendicular to the external field, and the coercivity is enhanced by this restraint. In contrast, when we reduce the inter-grain exchange interaction parallel to the external field, the coercivity decreases because the magnetization reversal process propagates owing to dipole interaction. These behaviors show that the coercivity of an isotropic permanent magnet depends on the direction of the inter-grain exchange interaction.

Permanent-magnet helical undulator for a millimeter-wave free electron laser

International Nuclear Information System (INIS)

Lee, Jongmin; Jeong, Young-Uk; Lee, Byung-Cheol; Kim, Sun-Kook; Cho, Sung-Oh

1995-01-01

Permanent-magnet helical undulator for a millimeter-wave free-electron laser was designed and constructed. The configuration of the undulator is based on bifilar-type permanent-magnet helical undulator and Halbach-type planar undulator. This new configuration shows enhanced magnetic field and low field error. Period, total length and peak magnetic-field amplitude of the undulator is 36 mm, 900 mm and 1.44 kG, respectively. Adiabatic tapering of the magnetic field in end sides of the undulator was achieved using stepped soft-iron tubes. (author)

Structure and soft magnetic properties of sputter deposited MnZn-ferrite films

NARCIS (Netherlands)

Gillies, M.F.; Coehoorn, R.; van Zon, J.B.A.D.; Alders, D.

1998-01-01

In this paper we report the soft magnetic properties of thin films of sputtered MnZn ferrite deposited on thermally oxidized Si substrates. A high deposition temperature, 600¿°C, together with the addition of water vapor to the sputtering gas was found to improve the initial ac permeability, µ. The

Impact of Nd{sup 3+} in CoFe{sub 2}O{sub 4} spinel ferrite nanoparticles on cation distribution, structural and magnetic properties

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