Provided is a method for manufacturing magnetic particles, in which an oxidation treatment, a reduction treatment, and a nitriding treatment are performed in that order on raw material particles with a core-shell structure in which a silicon oxide layer is formed on the surfaces of iron microparticles, thereby nitriding the iron microparticles while maintaining the core-shell structure. Due to this configuration, granular magnetic particles with a core-shell structure in which a silicon oxide layer is formed on the surfaces of iron nitride microparticles can be obtained.

A method for the production of a ferromagnetic material includes a first step wherein one or more nanometric functional coatings are deposited on a plurality of ferromagnetic particles and a second step wherein the coated ferromagnetic particles are consolidated to obtain the ferromagnetic material. The deposition of one or more functional coatings includes immersing the ferromagnetic particles in a first solution or suspension including a first reagent having a first (positive or negative) electrostatic charge or having polar groups (carboxylic acids, hydroxyl groups, etc.). The ferromagnetic particles immersed in the first solution or suspension are mixed for a predetermined time period and then immersed in a washing liquid, from which they are subsequently separated. The ferromagnetic particles are immersed in a second solution or suspension including a second reagent having a second electrostatic charge with a sign opposite to that of the first one or capable of interacting with the polar groups of the first reagent.

Provided is a method for manufacturing magnetic particles, in which an oxidation treatment, a reduction treatment, and a nitriding treatment are performed in that order on raw material particles with a core-shell structure in which a silicon oxide layer is formed on the surfaces of iron microparticles, thereby nitriding the iron microparticles while maintaining the core-shell structure. Due to this configuration, granular magnetic particles with a core-shell structure in which a silicon oxide layer is formed on the surfaces of iron nitride microparticles can be obtained.

A method for producing a sintered rare-earth magnet characterized by sintering a raw material that includes a ribbon-shaped polycrystalline phase with an average grain size of 10 to 200 nm fabricated by rapid solidification of an alloy melt having a rare-earth magnet composition, and a low-melting point phase formed on the surface of the polycrystalline phase and having a melting point lower than the polycrystalline phase.

Disclosed are a magnetic particle and a security ink containing the same. The magnetic particle includes a magnetic core, and a metal coating layer formed outside the magnetic core. The magnetic particle has a surface roughness (Ra) of 0.15 m or less. The magnetic particle according to the present invention is suitable for application to a security ink because an abnormal increase in particle size does not occur after the metal coating layer is formed.

Provided are a rare earth magnet and a method for manufacturing the same, which achieve both high magnetic properties and low eddy current loss. The rare earth magnet comprises coated magnet powder particles, each comprising a rare earth magnet powder particle and a coating of an insulating material on a surface thereof, wherein the insulating material contains nanoparticles, with which the rare earth magnet powder particle is coated. The method of manufacturing the rare earth magnet comprises a coating operation which includes adding an insulating material to the rare earth magnet powder particles, such that each coated magnet powder particle comprises a rare earth magnet powder particle and a coating of the insulating material on a surface thereof, wherein the coating operation comprises spraying a nanoparticle dispersion solution containing the nanoparticles and a binding agent, to the rare earth magnet powder particles that are caused to be tumbling and flowing.

Iron nitride nanoparticles and magnet materials made from iron nitride nanoparticles are described. The iron nitride nanoparticles have a core and a shell morphology. The shell is configured to provide a means to nitride the core. The magnetic materials are characterized as having an Msat greater than about 160 emu/g and a coercivity greater than about 700 Oe.

Iron nitride nanoparticles and magnet materials made from iron nitride nanoparticles are described. The iron nitride nanoparticles have a core and a shell morphology. The shell is configured to provide a means to nitride the core. The magnetic materials are characterized as having an Msat greater than about 160 emu/g and a coercivity greater than about 700 Oe.

Example nanoparticles may include an iron-based core, and a shell. The shell may include a non-magnetic, anti-ferromagnetic, or ferrimagnetic material. Example alloy compositions may include an iron-based grain, and a grain boundary. The grain boundary may include a non-magnetic, anti-ferromagnetic, or ferrimagnetic material. Example techniques for forming iron-based core-shell nanoparticles may include depositing a shell on an iron-based core. The depositing may include immersing the iron-based core in a salt composition for a predetermined period of time. The depositing may include milling the iron-based core with a salt composition for a predetermined period of time. Example techniques for treating a composition comprising core-shell nanoparticles may include nitriding the composition.

A method of producing a phosphate-coated SmFeN-based anisotropic magnetic powder, the method including performing a phosphate treatment including adding an inorganic acid to a slurry containing a raw material SmFeN-based anisotropic magnetic powder, water, a phosphate compound, and a rare earth compound so that the slurry is adjusted to have a pH of at least 1 and not higher than 4.5 to obtain a phosphate-coated SmFeN-based anisotropic magnetic powder having a surface coated with a phosphate.