Abstract: The present invention relates to a method of producing a magnetic particle including forming a layer containing an alloy particle that can form CuAu type or Cu3Au type hard magnetic order alloy phase on a support, oxidizing the layer, and annealing the layer in non-oxidizing atmosphere. The invention also relates to a method of producing a magnetic particle including producing an alloy particle that can form hard magnetic order alloy phase, oxidizing the alloy particle, and annealing the particle in non-oxidizing atmosphere, and a magnetic particle produced by the foregoing production method. Further, the invention relates to a magnetic recording medium comprising a magnetic layer containing a magnetic particle and a method of producing a magnetic recording medium including forming a layer containing an alloy that can form the foregoing hard magnetic order alloy phase, oxidizing the layer, and annealing the layer in non-oxidizing atmosphere.

Abstract: The present invention relates to a method of producing a magnetic particle including forming a layer containing an alloy particle that can form CuAu type or Cu3Au type hard magnetic order alloy phase on a support, oxidizing the layer, and annealing the layer in non-oxidizing atmosphere. The invention also relates to a method of producing a magnetic particle including producing an alloy particle that can form hard magnetic order alloy phase, oxidizing the alloy particle, and annealing the particle in non-oxidizing atmosphere, and a magnetic particle produced by the foregoing production method. Further, the invention relates to a magnetic recording medium comprising a magnetic layer containing a magnetic particle and a method of producing a magnetic recording medium including forming a layer containing an alloy that can form the foregoing hard magnetic order alloy phase, oxidizing the layer, and annealing the layer in non-oxidizing atmosphere.

Abstract: The present invention relates to a method of producing a magnetic particle including forming a layer containing an alloy particle that can form CuAu type or Cu3Au type hard magnetic order alloy phase on a support, oxidizing the layer, and annealing the layer in non-oxidizing atmosphere. The invention also relates to a method of producing a magnetic particle including producing an alloy particle that can form hard magnetic order alloy phase, oxidizing the alloy particle, and annealing the particle in non-oxidizing atmosphere, and a magnetic particle produced by the foregoing production method. Further, the invention relates to a magnetic recording medium comprising a magnetic layer containing a magnetic particle and a method of producing a magnetic recording medium including forming a layer containing an alloy that can form the foregoing hard magnetic order alloy phase, oxidizing the layer, and annealing the layer in non-oxidizing atmosphere.

Abstract: There is provided a method of manufacturing a magnetic particle, which comprises: the alloy particle preparation step of preparing an alloy particle capable of forming a CuAu type or Cu3Au type hard magnetic ordered alloy phase and the magnetic particle formation step; wherein in the alloy preparation formation step, by using a mixing and reaction device which has a stirring vane rotating at a high speed in the interior of a mixer, a plurality of kinds of solutions for preparing the alloy particle are supplied to the interior of the mixer, where the plurality of kinds of solutions L1 and L2 are mixed together and caused to react with each other by a liquid phase process, and at the same time the plurality of kinds of solutions are mixed together and caused to react with each other so that the peripheral speed in a leading end portion of the stirring vane is not less than 10 m/second.

Abstract: The solution I is spouted from a first nozzle into a mixing chamber as a high-pressure jet stream of not less than 1 MPa and as a turbulent flow having a Reynolds number of not less than 10000 during the flow into the mixing chamber, and the solution II having a lower pressure than the solution I is spouted from a second nozzle into the mixing chamber as an orthogonal flow which intersects the solution I almost at right angles. The two solutions are mixed together and caused to react with each other, with the result that a mixed reaction solution Z containing alloy particles Z is formed.

Abstract: The present invention provides a method for producing a magnetic recording medium having a magnetic layer on a substrate containing polybenzoxazole, wherein the magnetic layer is sequentially formed by: preparing alloy particles capable of forming ferromagnetic regular alloys having a CuAu or Cu3Au crystal structure; forming a coating film by applying the alloy particles on the substrate; and converting the alloy particles into magnetic particles by annealing the coating film so that the alloy particles are annealed. The invention also provides a magnetic recording medium having a magnetic layer which contains magnetic particles having ferromagnetic regular alloys having a CuAu or Cu3Au crystal structure and is produced by the method. A step for oxidizing the alloy particles is preferably provided between preparing the alloy particles and annealing the coating film.

Abstract: The present invention is a magnetic particle coated material comprising: a first support having a magnetic layer formed on one surface thereof; and a second support having a magnetic layer formed on one surface thereof, wherein the first support and the second support are attached to each other so that the other surfaces thereof on which the magnetic layers are not formed face each other, and the magnetic layers comprise magnetic particles having a CuAu type or Cu3Au type ferromagnetic ordered alloy phase.

Abstract: The present invention provides a magnetic particle-coated material having a layer including a CuAu type or Cu3Au type ferromagnetic ordered alloy phase on an organic support. Further, the present invention provides a method of manufacturing a magnetic particle-coated material that sequentially includes a step of manufacturing alloy particles capable of forming a ferromagnetic ordered alloy phase, a step of coating an organic support with the alloy particles to form a coating film, and a step of annealing the coating film in a reducing atmosphere to make the alloy particles into magnetic particles, and further includes a step of oxidizing the alloy particles, the oxidizing step being performed between the alloy particle manufacturing step and the annealing step.

Abstract: The present invention relates to a magnetic recording medium comprising a magnetic layer on at least one side of a nonmagnetic substrate, the magnetic layer containing magnetic particles of a CuAu type or Cu3Au type ferromagnetic ordered phase, wherein a conductive layer is provided on at least one side of the nonmagnetic substrate.

Abstract: The present invention relates to a method of producing a magnetic particle including forming a layer containing an alloy particle that can form CuAu type or Cu3Au type hard magnetic order alloy phase on a support, oxidizing the layer, and annealing the layer in non-oxidizing atmosphere. The invention also relates to a method of producing a magnetic particle including producing an alloy particle that can form hard magnetic order alloy phase, oxidizing the alloy particle, and annealing the particle in non-oxidizing atmosphere, and a magnetic particle produced by the foregoing production method. Further, the invention relates to a magnetic recording medium comprising a magnetic layer containing a magnetic particle and a method of producing a magnetic recording medium including forming a layer containing an alloy that can form the foregoing hard magnetic order alloy phase, oxidizing the layer, and annealing the layer in non-oxidizing atmosphere.

Abstract: The invention provides methods for producing nanoparticles having a CuAu type or Cu3Au type magnetically hard ordered alloy phase. One method includes a step of reducing, in liquid phase, a base metal and then reducing, in liquid phase, a noble metal. Another method includes a step of reducing, in liquid phase, at first a base metal and a part of a noble metal, and then reducing, in liquid phase, a remainder of the noble metal in liquid phase.

Abstract: A method of producing a nanoparticle, the method comprising: a reducing step of adding an reverse micelle solution (II) obtained by mixing a water-insoluble organic solvent containing a surfactant with an aqueous metal salt solution to an reverse micelle solution (I) obtained by mixing a water-insoluble organic solvent containing a surfactant with an aqueous reducing agent solution, to carry out a reducing reaction; and a maturing step of raising the temperature of the reduced mixture to mature the reduced mixture is provided. A method of producing a plural type alloy nanoparticle, the method comprising producing a nanoparticle made of a plural type alloy through a reducing step of mixing one or more reverse micelle solutions (I) containing a metal salt with an reverse micelle solution (II) containing a reducing agent to carry out reducing treatment and a maturing step of carrying out maturing treatment is also provided.

Abstract: A method of producing a magnetic recording medium including the steps of preparing alloy particles capable of forming a CuAu type or Cu3Au type ferromagnetic order alloy phase, forming an alloy particle layer on a support using the alloy particles, oxidizing the alloy particles, and annealing the alloy particle layer in a magnetic field under a reducing atmosphere. Also disclosed is a magnetic recording medium produced by the method, that is, a magnetic recording medium including a magnetic layer which contains magnetic particles in a CuAu type or Cu3Au type ferromagnetic order alloy phase and which has a squareness ratio of 0.75 or higher.

Abstract: The invention provides a method of producing a nanoparticle coated material, comprising a support and a nanoparticle layer formed on the support, wherein the nanoparticle layer contains nanoparticles comprising a CuAu type or Cu3Au type hard magnetic ordered alloy, and wherein the method satisfies at least one of the following conditions (i) and (ii): (i) the method comprises the steps of forming a shielding layer on the support before forming the nanoparticle layer; and (ii) a step of forming the nanoparticle layer comprises: the steps of applying a coating liquid containing nanoparticles capable of forming a CuAu type or Cu3Au type hard magnetic ordered alloy phase on the support to form a coating film; and irradiating laser light on the coating film.

Abstract: The present invention provides a magnetic recording medium comprising a support and a magnetic layer comprising a CuAu type or Cu3Au type magnetically hard ordered alloy phase, wherein a center line average roughness of a magnetic layer surface is 0.1 to 5 nm at a cut-off value of 0.25 mm, and a magnetic recording medium comprising a support and a magnetic layer containing, in a nonmagnetic metal oxide matrix, metal nanoparticles having a CuAu type or Cu3Au type magnetically hard ordered alloy phase.

Abstract: A rewritable or write-once medium with increased recording density and sensitivity is disclosed, the medium having at least a first dielectric layer, a recording layer and a second dielectric layer in this order on a substrate, wherein at least one of the first and second dielectric layers is formed by applying a colloidal dispersion which comprises inorganic dielectric nanoparticles having an average particle size of 1 to 50 nm and having the surface thereof modified with an adsorptive compound, and the recording layer is formed by applying a colloidal dispersion which comprises metal chalcogenide nanoparticles having an average particle size of 1 to 20 nm and having the surface thereof modified with an adsorptive compound. The dielectric layer and the recording layer are formed by spin coating or web coating.

Abstract: Ferromagnetic nanoparticles which are produced by reducing, in the presence of a polymer, two or more metals having different reduction potentials twice or more, using two or more reducing agents having different reduction potentials, a material coated with a dispersion of ferromagnetic nanoparticles in which the ferromagnetic nanoparticles are dispersed, and a magnetic recording medium which has a magnetic layer consisting of the material. The ferromagnetic nanoparticles having a holding power Hc of 95.5 kA/m or more, the material coated with the dispersion of ferromagnetic nanoparticles having excellent industrial coatability, and the magnetic recording medium using the dispersion are provided.

Abstract: An optical recording medium comprising a recording layer containing ultrafine particles of a metal selected from the Group 8 and Group 1B elements, said particles having an average particle size of 1 nm to 50 nm, and surfaces thereof being modified with an adsorptive compound.

Abstract: A rewritable or write-once medium with increased recording density and sensitivity is disclosed, the medium having at least a first dielectric layer, a recording layer and a second dielectric layer in this order on a substrate, wherein at least one of the first and second dielectric layers is formed by applying a colloidal dispersion which comprises inorganic dielectric nanoparticles having an average particle size of 1 to 50 nm and having the surface thereof modified with an adsorptive compound, and the recording layer is formed by applying a colloidal dispersion which comprises metal chalcogenide nanoparticles having an average particle size of 1 to 20 nm and having the surface thereof modified with an adsorptive compound. The dielectric layer and the recording layer are formed by spin coating or web coating.

Abstract: An optical recording medium comprises a recording layer containing, as a photoresponsive material, metal chalcogenide nanoparticles, wherein the metal chalcogenide nanoparticles have an average particle size of 1 to 20 nm and have a surface modified with an adsorbable compound.