Abstract: A method in which a metal powder is produced by ejecting a thermally decomposable metal compound powder into a reaction vessel through a nozzle together with a carrier gas under the condition V/S>600, where V is the flow rate of the carrier gas per unit time (liter/min), and S is the cross-sectional area of the nozzle opening part (cm2), and heating this metal powder at a temperature which is higher than the decomposition temperature of the metal compound powder and not lower than (Tm?200)° C., where Tm is the melting point of the metal, in a state where the metal compound powder is dispersed in the gas phase at a concentration of 10 g/liter or less. The method provides a fine, spherical, highly-crystallized metal powder which has a high purity, high density, high dispersibility and extremely uniform particle size, at low cost and using a simple process.

Abstract: A method of manufacturing a highly crystallized phosphor powder, comprising: making a raw material solution containing metal elements and/or semimetal elements that will be constituents of the phosphor into fine liquid droplets, subjecting the liquid droplets to decomposition by heating at a temperature of 500 to 1800° C. to produce hollow precursor particles and/or porous precursor particles, heating the precursor particles to crystallize the precursor particles while maintaining the hollow or porous form, and grinding the crystallized particles down to a predetermined particle size. The obtained phosphor powder is a high luminance inorganic phosphor powder that is extremely fine, and yet has few defects on the surface of or inside the powder, and hence has excellent crystallinity and light emission characteristics, and provides a phosphor composition useful for producing a phosphor layer with high coverage and high luminance of light emission.

Abstract: A ferrite fine powder having a mean particle size of 0.1 to 30 &mgr;m and made of spherical single-crystal particles. The ferrite fine powder has superior physical properties and excellent magnetic properties desirable for use as a raw material for a dust core of coils, transformers, etc. The powder is prepared by forming a solution or suspension containing a compound or compounds of at least one of the metals forming the ferrite into fine droplets, and thermally decomposing the droplets at elevated temperatures.

Abstract: A method in which a metal powder is produced by ejecting a thermally decomposable metal compound powder into a reaction vessel through a nozzle together with a carrier gas under the condition V/S>600, where V is the flow rate of the carrier gas per unit time (liter/min), and S is the cross-sectional area of the nozzle opening part (cm2), and heating this metal powder at a temperature which is higher than the decomposition temperature of the metal compound powder and not lower than (Tm−200)° C., where Tm is the melting point of the metal, in a state where the metal compound powder is dispersed in the gas phase at a concentration of 10 g/liter or less. The method provides a fine, spherical, highly-crystallized metal powder which has a high purity, high density, high dispersibility and extremely uniform particle size, at low cost and using a simple process.

Abstract: A method for manufacturing a highly-crystallized oxide powder, wherein an oxide powder is produced by ejecting a starting material powder comprising at least one metal element and/or semimetal element, which will become a constituent component of the oxide, into a reaction vessel together with a carrier gas through a nozzle; and heating the starting material powder at a temperature higher than the decomposition temperature or reaction temperature thereof and not lower than (Tm/2)° C., where Tm° C. stands for a melting point of the oxide, in a state in which the starting material powder is dispersed in a gas phase at a concentration of not higher than 10 g/L. In the above method, the starting material powder may be mixed and dispersed in the carrier gas by using a dispersing machine prior to being ejected into the reaction vessel through a nozzle.

Abstract: A method for manufacturing a highly-crystallized double oxide powder composed of a single crystal phase by forming fine droplets of a raw material solution containing a raw material compound that includes at least one metal element and/or at least one semi-metal element that constitutes a double oxide, and heating these droplets at a high temperature, wherein the raw material solution is a solution which exhibits only one main peak attributable to the decomposition reaction of the raw material compound or a reaction intermediate thereof in a DTA profile when the solution is dried and solidified and subjected to TG-DTA measurement. The method provides a highly-crystallized double oxide powder which is free from inclusion of impurities, has a high dispersibility and a uniform particle size, and composed of a single crystal phase, by a simple procedure at low cost.

Abstract: A method for preparing a highly crystallized metal powder, comprising: supplying at least one heat-decomposable metal compound powder into a reaction vessel using a carrier gas; and forming a metal powder by heating the metal compound powder in a state in which the metal compound powder is dispersed in a gas phase at a concentration of no more than 10 g/liter, at a temperature that is over the decomposition temperature of the metal compound powder and at least (Tm−200)° C. when the melting point of the metal contained in the metal compound powder is Tm° C. The method provides a high-purity, high-density, highly dispersible, fine, highly crystallized metal powder consisting of spherical particles of uniform size, which is suited to use in thick film pastes, and particularly conductor pastes and the like used in the preparation of multilayer ceramic electronic parts.

Abstract: A method for preparing a highly crystallized metal powder, involving the steps of: supplying at least one heat-decomposable metal compound powder into a reaction vessel using a carrier gas; and forming a metal powder by heating the metal compound powder in a state in which the metal compound powder is dispersed in a gas phase at a concentration of no more than 10 g/liter, at a temperature that is over the decomposition temperature of the metal compound powder and at least (Tm −200)° C. when the melting point of the metal contained in the metal compound powder is Tm° C. The method provides a high-purity, high-density, highly dispersible, fine, highly crystallized metal powder consisting of spherical particles of uniform size, which is suitable for use in thick film pastes, and particularly conductor pastes and the like used in the preparation of multilayer ceramic electronic parts.

Abstract: Nickel composite particles having a layer of a nickel-containing spinel on at least a part of the surface of nickel particles, or nickel composite particles having an oxide layer of metals other than nickel on at least a part of the surface of nickel particles and a layer of a nickel-containing spinel at an interface between the nickel particles and the metal oxide layer. The nickel composite particles are produced by forming fine liquid droplets from a solution containing (a) at least one thermally decomposable nickel compound and (b) at least one thermally decomposable metal compound capable of forming a spinel together with nickel; and heating the liquid droplets at a temperature higher than the decomposition temperatures of the compound (a) and (b) to nickel particles and simultaneously deposit a nickel-containing spinel layer, or further a metal oxide layer on the spinel layer.

Abstract: Nickel composite particles having a layer of a nickel-containing spinel on at least a part of the surface of nickel particles, or nickel composite particles having an oxide layer of metals other than nickel on at least a part of the surface of nickel particles and a layer of a nickel-containing spinel at an interface between the nickel particles and the metal oxide layer. The nickel composite particles are produced by forming fine liquid droplets from a solution containing (a) at least one thermally decomposable nickel compound and (b) at least one thermally decomposable metal compound capable of forming a spinel together with nickel; and heating the liquid droplets at a temperature higher than the decomposition temperatures of the compound (a) and (b) to nickel particles and simultaneously deposit a nickel-containing spinel layer, or further a metal oxide layer on the spinel layer.

Abstract: Nickel composite particles having a layer of a nickel-containing spinel on at least a part of the surface of nickel particles, or nickel composite particles having an oxide layer of a metal other than nickel on at least a part of the surface of nickel particles and a layer of a nickel-containing spinel at an interface between the nickel particles and the metal oxide layer. The nickel composite particles are produced by forming fine liquid droplets from a solution containing (a) at least one thermally decomposable nickel compound and (b) at least one thermally decomposable metal compound capable of forming a spinel together with nickel; and heating the liquid droplets at a temperature higher than the decomposition temperatures of compounds (a) and (b) to form nickel particles and simultaneously deposit a nickel-containing spinel layer, or further, a metal oxide layer on the spinel layer.

Abstract: A ferrite fine powder having a mean particle size of 0.1 to 30 &mgr;m and consisting of spherical single-crystal particles. The ferrite fine powder has superior physical properties and excellent magnetic properties desirable for the use as a raw material for a dust core of coils, transformers, etc. The powder is prepared by forming a solution or suspension containing a compound or compounds of at least one of the metals composing ferrite into fine droplets, and thermally decomposing the droplets at elevated temperatures.

Abstract: A method for preparing a highly crystallized metal powder, comprising: supplying at least one heat-decomposable metal compound powder into a reaction vessel using a carrier gas; and forming a metal powder by heating the metal compound powder in a state in which the metal compound powder is dispersed in a gas phase at a concentration of no more than 10 g/liter, at a temperature that is over the decomposition temperature of the metal compound powder and at least (Tm −200)° C. when the melting point of the metal contained in the metal compound powder is Tm° C. The method provides a high-purity, high-density, highly dispersible, fine, highly crystallized metal powder consisting of spherical particles of uniform size, which is suited to use in thick film pastes, and particularly conductor pastes and the like used in the preparation of multilayer ceramic electronic parts.

Abstract: A metal powder having a vitreous thin layer on at least a part of the surface thereof wherein the amount of the vitreous thin layer is preferably 0.01 to 50% by weight based on the metal powder without the vitreous thin layer. The metal powder is prepared by a process comprising the steps of: bringing a solution comprising a heat-decomposable metal compound to fine droplets; and heating the droplets to a temperature above the decomposition temperature of the metal compound, wherein a precursor of an oxide, heat-decomposable to produce a vitreous material which, together with the metal, does not form a solid solution, is added to the solution and the vitreous material is deposited, upon the heating, in the vicinity of the surface of the metal powder. The powder is useful for the preparation of a thick film paste used in a multilayer ceramic electronic component or substrate, since it has an excellent oxidation resistance during storage, in a conductor paste, and during firing of the paste.

Abstract: A nickel powder having at at least part of the surface thereof a layer of a composite oxide represented by the formula: A.sub.x B.sub.y O.sub.(x+2y), wherein A stands for at least one element selected from the group consisting of Ca, Sr and Ba; B stands for at least one element selected from the group consisting of Ti and Zr; and x and y represent numbers satisfying the formula: 0.5.ltoreq.y/x.ltoreq.4.5). The nickel powder may further contains at least one selected from among boron oxide, aluminum oxide and silicon oxide. The nickel powder is produced by spray pyrolyzing a solution of thermal decomposable starting compounds of nickel and additive elements and the resultant powder is suitable for use in a thick-film conductor paste having a sintering-starting temperature close to that of ceramic layers and a shrinkage behavior close to that of a ceramic without detriment to the conductivity and electric properties thereof.

Abstract: A process for preparing a metal powder, comprising the steps of: bringing a solution comprising at least one metal salt to fine droplets; and heating the droplets to a temperature above the decomposition temperature of the metal salt, wherein at least one compound which is heat-decomposable to produce a metal, a semimetal or an oxide of the metal or semimetal capable of remaining unmelted upon heating at the heat temperature is added to the solution and at least one selected from the group consisting of the metal, semimetal and oxide is heat-segregated in the vicinity of the surface of the metal powder. The resultant metal powder has a uniform particle size and good dispersibility without fusing or aggregation and is useful for the preparation of thick film pastes used in electronic circuits or components.

Abstract: A nickel powder having a composite oxide layer comprising lanthanum and nickel and, optionally an oxide of chromium, on at least a part of the surface thereof. The nickel powder is produced by a process comprising the steps of: bringing a solution comprising at least one heat-decomposable nickel compound and at least one heat-decomposable lanthanum compound and, optionally, at least one heat-decomposable chromium compound, to fine droplets; and heating the droplets at a temperature above the decomposition temperatures of these compounds to prepare a nickel powder and, at the same time, to deposit a composite oxide layer comprising lanthanum and nickel and, when present, chromium oxide, in the vicinity of the surface of the nickel powder.