A method for efficiently preparing ferrate based on nascent state interfacial activity. The method is as follows: (a) preparing nascent iron solution; (b) adding an oxidizing agent to the iron solution of step (a); (c) adding alkali solution or alkali particles to the mixed solution of step (b), mixing by stirring, and carrying out solid-liquid separation; (d) adding a stabilizing agent to the liquid separated out in step (c), and thus obtaining ferrate solution. The yield is 78-98%. The prepared ferrate solution is stable and can be stored for 3-15 days.

An object of the present invention is to provide a ferrite carrier core material for an electrophotographic developer having desired resistance properties and charging properties with small environmental variation of resistivity and charge amount while maintaining the advantages of ferrite carriers, a ferrite carrier for an electrophotographic developer, an electrophotographic developer using the ferrite carrier, and a method for manufacturing the ferrite carrier core material for an electrophotographic developer. In order to solve the problem, a ferrite carrier core material comprising ferrite particles containing 15 mass % or more and 25 mass % or less of Mn, 0.5 mass % or more and 5.0 mass % or less of Mg, 0.05 mass % or more and 4.0 mass % of Sr, and 45 mass % or more and 55 mass % or less of Fe, with Si localized in the surface thereof is used.

Ferrite powder of the present invention is ferrite powder detectable with a metal detector, comprising: hard ferrite particles containing Sr of 7.8 mass % or more and 9.0 mass % or less and Fe of 61.0 mass % or more and 65.0 mass % or less, wherein an amount of Na to be measured by ion chromatography is 1 ppm or more and 200 ppm or less. It is preferable that a volume average particle diameter of the particles constituting the ferrite powder is 0.1 m or more and 100 m or less. It is preferable that residual magnetization by a VSM measurement when magnetic field of 10 K.Math.1000/4A/m is applied is 25 A.Math.m.sup.2/kg or more and 40 A.Math.m.sup.2/kg or less.

A method for efficiently preparing ferrate based on nascent state interfacial activity. The method is as follows: (a) preparing nascent iron solution; (b) adding an oxidizing agent to the iron solution of step (a); (c) adding alkali solution or alkali particles to the mixed solution of step (b), mixing by stirring, and carrying out solid-liquid separation; (d) adding a stabilizing agent to the liquid separated out in step (c), and thus obtaining ferrate solution. The yield is 78-98%. The prepared ferrate solution is stable and can be stored for 3-15 days.

A method for manufacturing a magnetic powder includes changing a coercive force of a magnetic powder by irradiation with a radiation.

The present disclosure provides for compositions of magnetic nanoparticles and methods of making magnetic nano-particles with large magnetic diameters.

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 hexagonal strontium ferrite powder for magnetic recording, in which an activation volume is 800 to 1,500 nm.sup.3, a content of rare earth atom with respect to 100 atom % of iron atom is 0.5 to 5.0 atom %, and a rare earth atom surface portion uneven distribution is provided.

Use of supercritical CO2 for cleaning long, narrow pipes with a cross sectional area of less than 1000 square mm and a length of more than 500 meter. Cleaning is performed by adding a fluid to the lumen of the pipe (140); providing the fluid (2) in a supercritical state (6) inside the lumen; and subsequently, as a flushing step, while the fluid is in the supercritical state or in a liquid state, displacing the fluid (2) in the lumen of the pipe (140) and out of lumen of the pipe at a speed that causes a turbulent flow of the fluid, thereby flushing particles out of the lumen.

Disclosed are embodiments of synthetic garnet materials for use in radiofrequency applications. In some embodiments, increased amounts of gadolinium can be added into specific sites in the crystal structure of the synthetic garnet by incorporating indium, a trivalent element. By including both indium and increased amounts of gadolinium, the dielectric constant can be improved. Thus, embodiments of the disclosed material can be advantageous in both above and below resonance applications, such as for isolators and circulators.