Abstract: An article and thermoplastic composition including polycarbonate, a polysiloxane-polycarbonate and an x-ray detectable or metal detectable agent having good magnetic permeability and/or electrical conductivity wherein the composition may be used in articles for food preparation. The thermoplastic compositions are useful in forming molds for manufacturing a food product, such as chocolate molds.

Abstract: A curable composition comprising magnetically active elastic microspheres that are filled with a curing agent. The elastomeric microspheres are predispersed throughout the curable resin and are magnetostrictive. Cure of the adhesive is initiated when an external magnetic field is applied that physically distorts or ruptures the magnetic microspheres due to a magnetostrictive effect from the magnetic field.

Abstract: A microcapsule, a structure including a microcapsule, an article including a microcapsule and a method of preparing microcapsules provided, the microcapsule includes at least one material selected from the group consisting of a magnetic substance, a dielectric substance and a combination thereof. The microcapsule also includes a volatile material.

Abstract: A magnetic material composed of ?-InxFe2-xO3 (wherein 0<x?0.30) crystal in which In is substituted for a portion of the Fe sites of the ?-Fe2O3 crystal. The crystal exhibits an X-ray diffraction pattern similar to that of an ?-Fe2O3 crystal structure and has the same space group as that of an ?-Fe2O3. The In content imparts to the magnetic material a magnetic phase transition temperature that is lower than that of the ?-Fe2O3 and a spin reorientation temperature that is higher than that of the ?-Fe2O3. The In content can also give the magnetic material a peak temperature of the imaginary part of the complex dielectric constant that is higher than that of the ?-Fe2O3.

Abstract: A method for providing nanoparticle clusters of controlled dimensions is described. The method involves an activation of individual nanoparticles and the subsequent interaction between activated particles to form a cluster.

Abstract: The invention relates to a method for producing magnetic nanoparticles which are made of metal oxide-polymer composites and are provided with an increased magnetic mobility, among other things, due the high metal oxide content and the morphological structure thereof. High-pressure homogenization has proven to be a reliable technique for producing the inventive magnetic nanoparticles. According to said technique, the components metal oxide and polymer are processed in a carrier medium. Water is used in most cases at pressures ranging from 500 bar to 1200 bar while using great shearing forces. High pressure homogenization creates a colloidally stable magnetic particle population having a diameter ranging below 200 nm while also resulting in the produced magnetic nanoparticles being provided with greater magnetic moments than the metal oxide used as an initial material at low magnetic field strengths.

Abstract: A magnetically soft powder composite material is described, which is composed of at least 99.4 wt. % of a pure iron powder, a phosphatized iron powder, or an iron alloy powder and 0.05 wt. % to 0.6 wt. % of a soft ferrite powder and which is primarily suited for use in rapidly switching solenoid valves in motor vehicle engines. Furthermore, a method for manufacturing such a magnetically soft powder composite material includes the following method steps: a) preparation of a starting mixture including a pure iron powder, a phosphatized iron powder, or an iron alloy powder and a soft ferrite powder, b) mixing of the starting mixture, c) compacting of the starting mixture in a press under increased pressure, d) debinding of the compacted starting mixture in an inert gas atmosphere or in an oxygen-containing gas atmosphere, and e) heat treatment of the compacted starting mixture in an oxidizing gas atmosphere at a temperature of 410° C. to 500° C.

Abstract: In a soft magnetic material, multiple flake-shaped magnetic particles: are coated by respective magnetic insulators; contain respective groups of magnetic nanoparticles; and are compacted to achieve magnetic exchange coupling between adjacent flake-shaped magnetic particles, and between adjacent magnetic nanoparticles within at least one of the flake-shaped magnetic particles.

Abstract: The present invention is related to a method for isolating a target nucleic acid from a sample comprising said target nucleic acid, comprising the steps of mixing a sample containing said target nucleic acid with a binding solution and a nucleic acid binding matrix, binding at least part of said target nucleic acid to said nucleic acid binding matrix, wherein said nucleic acid binding matrix is treated simultaneously or has been previously treated with at least one compound comprising a metal substance selected from the group consisting of metals of the main groups 13 to 16, semimetals and transition metals for reducing non-target nucleic acid contaminations or wherein said nucleic acid binding matrix is modified with hydrophobic groups. Furthermore, respective kits and reagents are provided with the teaching of the present invention.

Abstract: An aspect of the present invention relates to a method of modifying a surface of a powder, comprising mixing a powder with a compound denoted by general formula (I): wherein, in general formula (I), each of R10 and R13 independently denotes a hydrogen atom, alkyl group, or aryl group, each of R11 and R12 independently denotes an alkyl group or an aryl group, and L denotes a single bond or an oxygen atom.

Abstract: In a food processing line, the equipment which is likely to fragment on breakage contains magnetically susceptible particles which are separated from the food by a magnetic separation stage. When the equipment is a starch carrying tray, the moulding mix contains 5-50% of magnetic filler, such as magnetite. Reinforcement with glass fibre and jute fibre modifies the compositions for moulding the trays. Moulding mixes based on polypropylene and thermosetting resins are described. A processing line using starch trays has a conveyor for food items and a conveyor for the starch in which the food items are moulded. Both have magnetic separators.

Abstract: There are provided a composite magnetic body exhibiting a sufficiently low magnetic loss at frequencies of several hundreds of megahertz to several gigahertz, and a method of manufacturing the same. The composite magnetic body contains a magnetic powder dispersed in an insulating material. The magnetic powder is in a spherical shape or an elliptic shape. The composite magnetic body has any one of the following characteristics (a) to (c): (a) the relative magnetic permeability ?r is larger than 1 and the loss tangent tan ? is 0.1 or less, at a frequency of 1 GHz or 500 MHz; (b) the real part ?r? of the complex permeability is more than 10 and the loss tangent tan ? is 0.3 or less, at a frequency of 1.2 GHz or less; and (c) the real part ?r? of the complex permeability is more than 1 at a frequency of 4 GHz or less, and the loss tangent tan ? is 0.1 or less at a frequency of 1 GHz or less.

Abstract: The present invention provides functional particles capable of effectively adsorbing impurities in water treatment. The particles can be rapidly separated by use of magnetic force, and hence are excellent in workability. They are magnetic particles having surfaces modified with amphipathic groups loaded thereon. The amphipathic group comprises an ammonium or carboxylate group as a hydrophilic moiety and a hydrocarbon group as a hydrophobic moiety. The hydrophobic moiety has a function of adsorbing the impurities, and the hydrophilic moiety has a function of dispersing the particles stably in water.

Abstract: An ink including stabilized magnetic single-crystal nanoparticles, wherein the value of the magnetic anisotropy of the magnetic nanoparticles is greater than or equal to 2×104 J/m3. The magnetic nanoparticle may be a ferromagnetic nanoparticle, such as FePt. The ink includes a magnetic material that minimizes the size of the particle, resulting in excellent magnetic pigment dispersion stability, particularly in non-aqueous inkjet inks. The smaller sized magnetic particles of the ink also maintains excellent magnetic properties, thereby reducing the amount of magnetic particle loading required in the ink.

Abstract: The subject of the invention is superparamagnetic nanoparticle probes based on iron oxides, to advantage magnetite or maghemite, with modified surface, coated with mono-, di- or polysaccharides from the group including D-arabinose, D-glucose, D-galactose, D-mannose, lactose, maltose, dextrans and dextrins, or with amino acids or poly(amino acid)s from the group including alanine, glycine, glutamine, asparagine, histidine, arginine, L-lysine, aspartic and glutamic acid or with synthetic polymers based on (meth)acrylic acid and their derivatives selected from the group containing poly(N,N-dimethylacrylamide), poly(N,N-dimethylmethacrylamide), poly(N,N-diethylacrylamide), poly(N,N-diethylmethacrylamide), poly(N-isopropylacrylamide), poly(N-isopropylmethacrylamide), which form a colloid consisting of particles with narrow distribution with polydispersity index smaller than 1.3, the average size of which amounts to 0.5-30 nm, to advantage 1-10 nm, the iron content is 70-99.9 wt. %, to advantage 90 wt.

Abstract: The invention relates to a soft-magnetic material comprising a micro fraction composed of particles of a soft-magnetic material having a particle size in the range from 1 to 100 ?m and a nano fraction composed of particles of a soft-magnetic material having a particle size in the range from 100 to 200 nm, where the proportion of the nano fraction based on the total mass of micro fraction and nano fraction is from 5 to 70% by mass and the particles of the micro fraction and the particles of the nano fraction optionally consist of the same material, and also a process for producing an article composed of the soft-magnetic material.

Abstract: A process for the preparation of polymer magnetic particles, which comprises: providing a water phase containing magnetic components homogeneously dispersed therein, wherein the water phase is contacted with or further contains a polymerisable metal-containing or organic monomer which is soluble in the water phase, and polymerizing the monomer in the presence of the magnetic components so as to form polymer magnetic particles in which the magnetic components are substantially uniformly distributed; wherein at least a part of the polymerizing step is carried out in a water-in-oil emulsion in which the water phase containing the magnetic components homogenously dispersed therein is present as a discontinuous phase in a continuous oil phase.

Abstract: The ferrite sintered body of the present invention contains main components consisting of 52 to 54 mol % Fe2O3, 35 to 42 mol % MnO and 6 to 11 mol % ZnO as oxide equivalents and additives including Co, Ti, Si and Ca in specified amounts, and has a temperature at which the power loss is a minimal value (bottom temperature) of higher than 120° C. in a magnetic field with an excitation magnetic flux density of 200 mT and a frequency of 100 kHz, and a power loss of 350 kW/m3 or less at the bottom temperature.

Abstract: A method for producing ferrite particles by weighing, mixing, then crushing ferrite raw materials, and granulating the resultant slurry, and then sintering the resultant granulated material using a rotary furnace, wherein the sintering is carried out under a positive pressure reducing atmosphere.

Abstract: The present invention relates to ferromagnetic metal particles having a bulk density (?a) of not more than 0.25 g/cm3, a process for producing the above ferromagnetic metal particles and a magnetic recording medium comprising a non-magnetic substrate; a non-magnetic undercoat layer formed on the non-magnetic substrate which comprises non-magnetic particles and a binder resin; and a magnetic recording layer formed on the non-magnetic undercoat layer which comprises magnetic particles and a binder resin, wherein the above ferromagnetic metal particles were used as the magnetic particles.

Abstract: Thermal treatment of transition metal ferrite nanoparticles at moderate temperatures provides materials with desirable magnetic properties. AxFe3-xO4 nanoparticles, e.g., with metal ratio from x=0.4 to 1.0, can be prepared according to standard solution micelle techniques. While the materials produced by micelle synthesis, such as CoFe2O4 nanoparticles, appeared to be comprised of mainly the magnetite phase (e.g., CoFe2O4) by x-ray diffraction, multiphase materials were observed after the transition metal ferrite nanoparticles were subjected to thermal treatment under nitrogen. Magnetization as a function of applied field and temperature reveal variations in saturation magnetization, coercivity, blocking temperature and Verwey transition temperature dependence as a function of composition. Extremely high saturation magnetization with low coercivity can be achieved with such compositions.

Abstract: Magnetic receptive Paints and coatings have been developed to allow one to paint a wall with this coating and apply magnets to this surface. The further development of magnetic receptive coatings incorporates the use of multiple size particles giving the finished surface a smoother appearance and increasing the particle load in the dry mill surface. This is useful in the coating of substrates where the need to coat the thinnest possible coating on the surface of a substrate such as papers and films as well as painting on walls, gives you the highest magnetic receptive surface possible at the thinnest mill thickness of applied coating.

Abstract: There is provided a method of producing composite particles each comprising a polymer compound and solid particles, the method including: (1) mixing a first liquid containing a monomer and an organic solvent with solid particles to prepare a mixed solution; (2) preparing a second liquid; (3) mixing the mixed solution with the second liquid to form an emulsion; (4) fractionating the first liquid from a dispersoid of the emulsion; and (5) polymerizing the monomer remaining in the dispersoid after the fractionation. Composite particles each comprising solid particles uniformly at a high ratio and having excellent size uniformity and dispersibility can be obtained thereby.

Abstract: A thin soft magnetic film combines a high magnetization with an insulating character. The film is formed by nitriding Fe-rich ferromagnetic nanograins immersed in an amorphous substrate. A selective oxidation of the amorphous substrate is then performed. The result is a thin, insulating, soft magnetic film of high magnetization. Many types of integrated circuits can be made which include a component using a membrane incorporating the above-mentioned thin film.

Abstract: The invention relates to a composite material formed by microparticles of magnetic material A and a conductive liquid B. The material is characterized in that the material A is chosen from magnetic compounds and magnetic alloys and is in the form of particles, the mean size of which is between 1 and 10 ?m, and in that the support fluid B is a conductive fluid chosen from metals, metal alloys and salts that are liquid at temperatures below the Curie temperature of the material A, or from mixtures thereof.

Abstract: There are provided a soft magnetic material in the form of particles for suppressing occurrence of electromagnetic interference which is capable of exhibiting the suppressing effect in a broad frequency range from a low frequency band to a high frequency band, as well as an electromagnetic interference suppressing sheet using the material. When a conductive magnetic filler prepared by mixing a conductive carbon with soft magnetic particles at a volume ratio of 3 to 10:50 to 70 is highly filled in a sheet material, there can be obtained an electromagnetic interference suppressing sheet which is suitable for high-density mounting to electronic equipments, has an excellent electromagnetic absorption in a near electromagnetic field, and is fully suppressed from undergoing electromagnetic reflection thereon.

Abstract: Magnetite powders are manufactured by first forming a precursor mixture containing iron atoms bonded to organic control agent molecules. Thereafter, magnetite is formed by (i) causing or allowing the iron atoms in the precursor mixture to form iron particles and (ii) reducing the iron atoms using a reducing agent. The magnetite powders obtained using the methods of the invention are superparamagnetic and can have very low densities. In one embodiment, the magnetite powders include a carbon coating on the magnetite particles which makes the particles resistant to being oxidized.

Abstract: The present invention relates to a method of producing a polymeric monolithic article by radical polymerization, which method comprises providing a mold comprising a solution of radically polymerisable monomers; a transition metal catalyst and a complexing ligand in a solvent; adding an ATRP initiator and, optionally, flushing the mixture with an inert gas; carrying out radical polymerisation in the mold; optionally, removing the monolithic article obtained in from the mold; and washing the monolithic article obtained as described above.

Abstract: An aspect of the present invention relates to an iron nitride powder. The iron nitride powder is comprised chiefly of Fe16N2 and comprises, on at least a portion of the powder surface, a coating layer comprising at least one element selected from the group consisting of rare earth metal elements, aluminum, and silicon, and cobalt-containing ferrite having a composition denoted by (CoxFe1?x)Fe2O4, wherein 0<x?1. The present invention further relates to a method of manufacturing iron nitride powders and a magnetic recording medium comprising the iron nitride powder.

Abstract: A particle having a core and a surface to which are covalently coupled a plurality of reactive ester groups. Methods for using the particle to prepare a particle having one or more of a plurality of a targeting agent, a diagnostic agent, or a therapeutic agent covalently coupled thereto.

Abstract: Electrically conductive, magnetic composite material, comprising (A) pulverulent, inorganic, magnetic material which is electrically not or only poorly conductive, and (B) an electrically conductive material, selected from the group consisting of pulverulent and liquid carbon-comprising organic materials and pulverulent carbon allotropes, in a ratio by weight of (A):(B)=from 1:100 to 100:1; a process for its production, and its use, and also ferrimagnetic mixed oxide (A) of the general formula I: M?M??O4??(I), in which M? is a first metal component which comprises divalent metal cations; and M?? is a second metal component which comprises trivalent metal cations; capable of production by reacting, in a quantitative ratio such that the resultant ferromagnetic mixed oxide (A) is electrically neutral, divalent metal cations M? and trivalent metal cations M?? in aqueous solution and/or dispersion, comprising at least one electrically conductive material (B) and/or at least one material which differs there

Abstract: Systems and methods for using microscopic capsules containing orientable materials for document security and processing applications are presented. A security application comprising a medium having a substrate and a plurality of microcapsules is disclosed. The microcapsules contain magnetically orientable material and a liquid. The magnetically orientable material is oriented in a first alignment. Application of a magnetic field to the medium orients the magnetically orientable material to a second alignment, thereby altering the opacity of the medium. Magnetic material may also be dragged into a concentrated arrangement by a magnetic field, thereby altering the opacity of the medium.

Abstract: Magnetic receptive Paints and coatings have been developed to allow one to paint a wall with this coating and apply magnets to this surface. The further development of magnetic receptive compounds lends itself to creating a one step process where one applies a magnetic receptive plaster or compound to a wall with a viscosity sufficient to smooth with a trowel leaving a magnetic receptive surface. In other applications one could spray a compound on a given surface.

Abstract: An composition exhibiting a desired value of magnetic susceptibility, which can be used to fabricate components in an NMR device, and method thereof, wherein the composition comprises a metal ion selected from the group consisting of Gd+3, Fe+3 and Mn+2 and an amorphous material using a ligand or chelating agent to solubilize the metal ion throughout the marphous material, wherein the magnetic susceptibility of the composition exhibits a desired value at cryogenic temperatures such as nearly zero susceptibility at temperatures at or below 77° K.

Abstract: Highly pure iron oxides are prepared by reaction of metallic iron, in the form of microspheroidal particles or of scraps or cuttings, with an agitated aqueous solution of a mono- or polycarboxylic acid with a pKa of 0.5 to 6 relative to the first carboxyl and capable of decomposing, by heating in air at 200 to 350 ° C., to carbon dioxide and water, using 0.03 to 1.5 moles of acid per g-atoms of iron, a water/iron weight ration of 1 to 20, and by oxidation of the ferrous carboxilate to ferric salt, with an agent selected from oxygen, mixtures containing oxygen, hydrogen peroxide, organic peroxides and hydroperoxides.

Abstract: A ferrite substrate for thin-film inductors is provided by means of blending raw materials to meet a composition of di-iron trioxide (Fe2O3): 40 to 55 mol %, nickel oxide (NiO): 5 to 35 mol %, zinc oxide (ZnO): 10 to 40 mol %, and bismuth trioxide (Bi2O3): 150 to 750 ppm, or of Fe2O3: 40 to 55 mol %, NiO: 5 to 35 mol %, ZnO: 10 to 40 mol %, cupric oxide (CuO): 5 to 10 mol %, and manganese dioxide (MnO2): 0.5 to 2 mol %, and then molding and sintering the blended material, and applying hot isostatic pressing to the sintered article. A thin-film common mode filter and a thin-film common mode filter array using the ferrite substrate and the manufacturing method of the substrate are also provided.

Abstract: Stimuli-responsive magnetic nanoparticles, methods of making the nanoparticles, and methods of using the nanoparticles.

Abstract: A method and structure for making magnetite nanoparticle materials by mixing iron salt with alcohol, carboxylic acid and amine in an organic solvent and heating the mixture to 200-360° C. is described. The size of the particles can be controlled either by changing the iron salt to acid/amine ratio or by coating small nanoparticles with more iron oxide. Magnetite nanoparticles in the size ranging from 2 nm to 20 nm with a narrow size distribution are obtained with the invention.

Abstract: A ferrite substrate for thin-film inductors is provided by means of blending raw materials to meet a composition of di-iron trioxide (Fe2O3): 40 to 55 mol %, nickel oxide (NiO): 5 to 35 mol %, zinc oxide (ZnO): 10 to 40 mol %, and bismuth trioxide (Bi2O3): 150 to 750 ppm, or of Fe2O3: 40 to 55 mol %, NiO: 5 to 35 mol %, ZnO: 10 to 40 mol %, cupric oxide (CuO): 5 to 10 mol %, and manganese dioxide (MnO2): 0.5 to 2 mol %, and then molding and sintering the blended material, and applying hot isostatic pressing to the sintered article. A thin-film common mode filter and a thin-film common mode filter array using the ferrite substrate and the manufacturing method of the substrate are also provided.

Abstract: Rubber compound containing at least one nanoscale, magnetic filler and at least one non-magnetic filler. Vulcanisable mixture containing the rubber compound and at least one crosslinking agent and/or vulcanisation accelerator. Moulding obtainable from the vulcanisable mixture by heat treatment or action of an electrical, magnetic or electromagnetic alternating field.

Abstract: The present invention relates to a material containing ionic groups that form an ionic pair with a free radical catalyst. In particular, the invention relates to materials that are magnetic, and to the methods of forming such materials. For example, a method of forming paramagnetic particles is disclosed, the method comprising contacting a substance having cationic groups with an aqueous solution of Fe3+ so that all the cationic groups are exchanged for Fe3+, adjusting the pH of the solution to between 9 and 10, to form Fe(III) hydroxide, reducing a portion of the Fe(III) hydroxide to Fe(II) hydroxide to obtain a blend of the Fe(III) hydroxide the Fe(II) hydroxide, and crystallizing the two iron hydroxides to form paramagnetic particles comprising magnetite. The invention also discloses the formation of polymers from the ionic groups within the material. Various applications of the resulting materials are also disclosed.

Abstract: The light-polarizing solid coating composition which comprises (i) particles of at least one magnetic material suspended in a solvent, is characterized in that it comprises (ii) at least one dichroic dye compound. Application to ophthalmic optics.

Abstract: The invention provides tissue markings (such as tattoos) comprising magnetic particles, e.g., magnetite, and methods for making and altering, e.g., removing them.

Abstract: One aspect of the present invention relates to a permanently linked, rigid, magnetic chain of particles prepared by sol-gel methods. A second aspect of the present invention relates to a method of preparing a permanently linked, rigid, magnetic chain of particles comprising: coating a core material with one or more polyelectrolyte layers resulting in a coated particle; further coating the coated particle with a layer of magnetic nanoparticles resulting in a magnetic particle; coating the magnetic particle with a layer of a polycationic polyelectrolyte resulting in a coated magnetic particle; and applying a magnetic field to the coated magnetic particle in the presence of a metal oxide or metal oxide precursor capable of undergoing hydrolysis.

Abstract: Magnetostrictive material based on cobalt ferrite is described. The cobalt ferrite is substituted with transition metals (such manganese (Mn), chromium (Cr), zinc (Zn) and copper (Cu) or mixtures thereof) by substituting the transition metals for iron or cobalt to form substituted cobalt ferrite that provides mechanical properties that make the substituted cobalt ferrite material effective for use as sensors and actuators. The substitution of transition metals lowers the Curie temperature of the material (as compared to cobalt ferrite) while maintaining a suitable magnetostriction for stress sensing applications.

Abstract: A method of recovering spilled hydrocarbon fluids from a body of water utilizing the increased oleophilic properties of reacted iron particles suspended in a magnetorheological (MR) fluid. The iron particles normally used to create MR fluids, are reacted with an organic compound containing an oleophilic chain end which attaches to the surface of the iron, prior to suspension in a liquid vehicle such as an organic oil. The reacted iron particles in the MR fluid are then applied to and mixed with a hydrocarbon spill on a body of water such as an oil spill, whereby subsequent exposure to a significant magnetic field provides for subsequent recovery of both the reacted magnetic particles and the hydrocarbon spill.

Abstract: A method of manufacturing fine particles of the invention includes introducing a reactive gas flow containing a fine particle source material into a reactor from one side, growing fine particles in a gas phase by heating the fine particle source material in the reactive gas flow, introducing a diluting gas flow into the reactor from another side being almost counter-flow to the reactive gas flow, equalizing flow rates of the reactive gas flow and the diluting gas flow substantially with respect to a cross section of a flow channel, and then stopping growth of the fine particles by merging the reactive gas flow and the diluting gas flow.

Abstract: A ferromagnetic material powder comprising a magnetic oxide which is a complex of a magnetite phase and a ferrite phase, wherein the ferromagnetic material powder has a spinel crystal structure and a magnetoplumbite crystal structure, and in the spinel crystal structure, the content of Fe3+ in site A is 35 to 50% and the content of Fe2+ in site B is 30 to 45%, a carrier for an electrophotographic developer, a process for producing them and an electrophotographic developer.

Abstract: The invention describes a method of preparing magnetic ferrites from layered precursors in which Fe2+ is first introduced into the layers of layered double hydroxides (LDHs) in order to prepare Me-Fe2+—Fe3+ LDHs, and then by utilizing the easily oxidized nature of Fe2+, binary or multi-component ferrite materials containing Fe3+ in a single crystalline phase can be prepared. Values of the saturation magnetization of ferrites prepared by the method are significantly increased compared with ferrites prepared by traditional methods. Because the metal elements in the layered precursor have the characteristics of a high degree of dispersion, high activity and small particle size (average particle size 40-200 nm), no milling is required before calcination, thus simplifying the production process, shortening the production period, reducing capital investment in equipment and economizing on energy costs. In addition, the method does not corrode production equipment and does not pollute the environment.

Abstract: Magnetite particles (and their manufacturing method) that enable suppression of blooming caused because of their large coercive force when used as magnetic toner, exert a light environment load, and are excellent in cost. The magnetite particles contain 0.1 to 1 mass % of phosphorus, have a coercive force of 10 to 25 kA/m at a load magnetic field of 796 kA/m, and have a shape of octahedron.