A powder for dust cores includes an aggregate of soft magnetic particles, each of which includes a soft magnetic metal particle, and a ferrite film that covers a surface of the soft magnetic metal particle and includes ferrite crystal grains having a spinel structure. A diffraction peak derived from the ferrite crystal grains exists in a powder X-ray diffraction pattern. By a method for producing a powder for dust cores, a raw material powder that includes an aggregate of soft magnetic metal particles is prepared. Furthermore, many ferrite fine particles are formed on a surface of each of the soft magnetic metal particles of the raw material powder. Additionally, the ferrite fine particles are coarsely crystallized through heat treatment to form a ferrite film, which includes ferrite crystal grains having a spinel structure, on the surface of the each of the soft magnetic metal particles.

Provided is a method for preparing a soft magnetic manganese-zinc ferrite composite by removing impurities from industrial waste step by step. Manganese-containing waste residue is crushed and dried, and then mixed with a flux in a muffle furnace and roasted at a temperature below 1000? C. till solid-liquid stratification; then, multi-step impurity removal is performed to obtain a high-purity quaternary purification solution of manganese sulfate. Similarly, zinc residue is melted to remove impurities, and then multi-step impurity removal is performed to obtain a high-purity quaternary purification solution of zinc sulfate. According to a manganese-zinc-iron ratio required for the manganese-zinc ferrite, the two purification solutions are mixed, and ferrous sulfate is added. The mixed purification solution is coprecipitated with ammonium bicarbonate, washing is performed, and co-precipitated powder is decomposed into ferric oxide, manganese tetroxide and zinc oxide which are then roasted to obtain the manganese-zinc ferrite composite.

The present invention provides a ferrite particle containing: a ferrite particle body having a spinel crystal structure belonging to a space group Fd-3m and having a spinel composition represented by the following formula (1); and a coating layer having a spinel crystal structure belonging to the space group Fd-3m and coating a surface of the ferrite particle body, in which the coating layer is a layer obtained by subjecting the ferrite represented by the following formula (1) to a heat treatment, and a content ratio of the coating layer in the ferrite particle obtained by subjecting a powder X-ray diffraction pattern to Rietveld analysis is 5 mass % or more and 35 mass % or less, and the ferrite particle satisfies a specific formula (2). The present invention also provides a carrier for an electrophotographic developer.

Magnetic powder includes: at least one epsilon-phase iron oxide-based compound selected from the group consisting of -Fe.sub.2O.sub.3 and a compound represented by Formula (1); and a surface treatment layer including a silane compound on at least a part of a surface. The magnetic powder has an average particle diameter of 8 nm to 20 nm. The content ratio of carbon atoms of the silane compound included in the surface treatment layer to iron atoms of the at least one epsilon-phase iron oxide-based compound selected from the group consisting of -Fe.sub.2O.sub.3 and the compound represented by Formula (1) is 0.05% to 0.5% in terms of the number of atoms. A manufacturing method thereof and applications thereof are also provided. In Formula (1), A represents at least one metal element other than Fe and a represents a number that satisfies a relationship of 0<a<2.

-A.sub.aFe.sub.2-aO.sub.3(1)

Coated iron oxide (10) nanocrystal structures, superparamagnetic 10 nanoparticles, methods for synthesizing coated 10 nanocrystal structures, and methods for synthesizing superparamagnetic 10 nanoparticles are described herein. A coated 10 nanocrystal structure may comprise an iron oxide core, a manganese ferrite shell layer surrounding the core, and a bilayer coating surrounding the shell layer. The bilayer coating may include an inner oleic acid layer surrounding the shell layer and an outer layer surrounding the inner oleic acid layer.

Provided are a ferrite powder capable of maintaining a high withstand voltage even when used in a resin composition having high magnetic properties and electrical resistivity and a high filling ratio, and a method for producing the same. A ferrite powder composed of spherical ferrite particles, wherein the ferrite powder contains iron (Fe): 55.0-70.0 mass % and manganese (Mn): 3.5-18.5 mass %, the ferrite powder containing more than 0.0 mass % to 7.5 mass % ?-Fe.sub.2O.sub.3, and the ferrite powder has a volume average particle size (D50) of 15.0 ?m or less.

A positive active material including: a core comprising a metal oxide, a non-metal oxide, or a combination thereof capable of intercalation and deintercalation of lithium ions or sodium ions; and a non-conductive carbonaceous film including oxygen on at least one portion of a surface of the core; a lithium battery including the positive active material; and a method of manufacturing the positive active material.

A method of producing one of magnetite and ferrite nanoparticles comprising the step of mixing an iron containing metal chemical with a fatty acid.

The present invention provides a spherical ferrite powder that is excellent in filling ability and moldability if used as a filler, is excellent in handling ability, and is high in resistivity; a resin compound including the ferrite powder; and a molded product made of the resin compound. The spherical ferrite powder including 15 to 30 wt % of ferrite particles having the particle diameter less than 11 m and have the volume average particle diameter of 10 to 50 m; the resin compound including the ferrite powder; and the molded product made of the resin compound are employed.

A set of spherical inorganic particles having the particular property of being spontaneously individualized, both in dry state in the form of a powder and when they are dispersed in a matrix. The method for producing the particles, and the materials produced by including the particles in the matrices are also described.