Provided is a porous silver powder and a preparation method thereof. More specifically, the present invention relates to porous silver powder that is easy to prepare, improves a sterilization effect because an specific surface area and a porosity are easily adjustable, improves electrical conductivity when molded as sintered body, contributes to reducing use of expensive silver when applied in various industrial fields, thus achieving price competitiveness, and is harmless to the human body because a particle size is adjustable to prevent the porous silver powder from being absorbed into the body; and a preparation method thereof.

A method for manufacturing a magnetic powder includes a step of producing a magnetic powder by spray-drying a spray liquid containing first magnetic particles, second magnetic particles, a thermosetting resin, and an organic solvent. A magnetic powder includes first magnetic particles and a thermosetting resin coating film on surfaces of the first magnetic particles. The first magnetic particles are soft magnetic metal particles. The resin coating film contains second magnetic particles. The second magnetic particles have a smaller average particle size than the first magnetic particles.

A magnet includes hard magnetic particles containing a rare-earth metal, and a soft magnetic material interposed between the hard magnetic particles to bind together the hard magnetic particles.

A magnet includes hard magnetic particles containing a rare-earth metal, and a soft magnetic material interposed between the hard magnetic particles to bind together the hard magnetic particles.

The present invention provides a method for the manufacture of transition metal oxide fine particles, the method comprising the steps of: heating a strong-alkaline aqueous solution while stirring same; adding to and dissolving in the heated strong-alkaline aqueous solution a transition metal oxide; adding a strong-acid aqueous solution to the strong alkaline aqueous solution in which the transition metal oxide is dissolved, while stirring same, thereby re-dissolving a solid generated at the interface between the strong-alkaline aqueous solution and the strong-acid aqueous solution; adjusting the pH of the mixed aqueous solution resulting from mixing the strong-alkaline aqueous solution and the strong acid aqueous solution, through adjustment of the adding rate and amount of the strong-acid aqueous solution, to precipitate transition metal oxide fine particles; and separating the transition metal oxide fine particles from the mixed aqueous solution and sequentially washing, drying, and thermally treating the separated transition metal oxide fine particles.

There is provided an inexpensive silver particle dispersing solution being usable as a slurry for ink jet, a method for producing the same, and a method for producing a conductive film using the silver particle dispersing solution. In a silver particle dispersing solution containing a silver powder and a solvent, the silver powder has an average primary particle diameter (D.sub.SEM) of 0.15 to 0.5 μm, and the ratio (D.sub.50/D.sub.SEM) of a particle diameter (D.sub.50), which corresponds to 50% of accumulation in volume-based cumulative distribution of the silver powder, to the average primary particle diameter (D.sub.SEM) is not less than 1.7, the silver powder having a fatty acid adhered to the surface thereof, and the solvent containing a monohydric higher alcohol having a carbon number of 6 to 12, butyl carbitol or butyl carbitol acetate as the main component thereof.

The present invention relates to a process for the preparation of thin silver nanoparticle layers, which are produced directly on a substrate as part of a coating or printing process. The layers show different colours in transmittance and reflectance. The layers do not show the typical conductivity of metallic layers, since the particles are essentially discrete particles which are not sintered. The invention further relates to decorative and security elements. When the layers are applied over a security element, such as a hologram, the obtained products show also different colours in reflection and transmission, an extremely bright optically variable image (OVD image) and high purity and contrast. Depending on the thickness of the layer a more or less intensive metallic aspect appears.

Provided is a method of producing spherical silver powder, which makes it possible to easily produce spherical silver powder having primary particle diameters with less variation than conventional powder and spherical silver powder obtained by the method.

The method of producing spherical silver powder includes a reduction precipitation step of precipitating silver particles by reduction by adding a reductant including hydrazine carbonate to an aqueous reaction system containing silver ions.

There are provided a spherical silver powder which has the same diameter as that of a spherical silver powder produced by a conventional wet reduction method and which can sufficiently sinter the silver particles thereof to cause the silver particles to be adhered to each other at a relatively low temperature to form a conductive film having a low volume resistivity when it is used for a baked type conductive paste, and a method for producing the same. A spherical silver powder, which contains a neutral or basic amino acid having a carbon number of not less than 5 in each of particles thereof and which has an average particle diameter D.sub.50 of 0.2 to 5 μm based on a laser diffraction method, is produced by adding the neutral or basic amino acid having the carbon number of not less than 5 (such as proline, tyrosine, tryptophan, phenylalanine, arginine or histidine) to a water reaction system containing silver ions to mix a reducing agent therewith to deposit silver particles by reduction.

There is provided a spherical silver powder which is capable of being sintered at a lower temperature. The spherical silver powder of spherical silver particles has cavities, each of which is formed in a corresponding one of the spherical silver particles and each of which has a major axis of 100 to 1000 nm and a minor axis of 10 nm or more, the ratio of the major axis to the minor axis (major axis/minor axis) being 5 or more, the major axis being the length of the long side of a rectangle which has a minimum area and which circumscribes the outline of a cross-section of a corresponding one of the cavities on an image of the cross-section of the corresponding one of the silver particles exposed by polishing the surface of a resin after the silver powder is embedded in the resin, and the minor axis being the length of the narrow side of the rectangle.