Sumitomo Chemical Company, Limited

Yoshio Uchida

Hisashi Watanabe

Masahide Mohri

Yoshinari Sawabe

Norio Matsuda

Shinichiro Tanaka

Ichiro Tanaka

Kazuo Sadaoka

Tetsuro Tohma

Tetsu Umeda

Takumi Shibuta

Toshifumi Katsuda

Seiji Tsuji

Ren-De Sun

The present invention provides a thermoelectric material useful for a thermoelectric converter having excellent energy conversion efficiency, and a method for producing the thermoelectric material. The thermoelectric material comprising an oxide containing Ti, M, and O and the oxide is represented by Formula (1).TiMO&#x2003;&#x2003;(1)M represents at least one selected from the group consisting of V, Nb, and Ta, x is not less than 0.05 and not more than 0.5, and y is not less than 1.90 and not more than 2.02.

Thermoelectric material, method for producing the same, and thermoelectric converter

Disclosed are a nickel hydroxide powder and a method for producing the same. The nickel hydroxide powder comprises a particle in the form of sphere, an average particle diameter of 0.1 &#x3bc;m or more and 30 &#x3bc;m or less, and the amount of the particles having a diameter of 0.7 times or more and 1.3 times or less the average particle diameter of 80% by weight or more based on the total amount of particles. The method for producing a nickel hydroxide powder comprises the steps of (1) to (4): (1) injecting a solution containing a nickel salt through a pore into a liquid mutually insoluble with the solution to obtain an emulsion including solution as a dispersed phase and the liquid as a continuous phase; (2) gelating the emulsion; (3) separating the dispersed phase from the obtained gel to obtain a cake; and (4) drying the cake.

Nickel hydroxide powder and method for producing same

A barium titanate powder and a method for producing the same are provided. The barium titanate powder comprises a perovskite structure having a ratio c/a of 1.008 or more and ratio d/D of from 1 to 1.5, wherein 'c' is a length of the c axis, 'a' is a length of the a axis in the perovskite structure, &#x201c;d&#x201d; is an average particle diameter and &#x201c;D&#x201d; is a equivalent specific surface area diameter. The method of producing a barium titanate powder, comprises the steps of: (1) heating a mixture containing a titanium compound and a barium compound under a gas atmosphere containing a halogen at a temperature of not less than about 200&#xb0; C. and less than the temperature for generation of barium titanate, (2) calcining the obtained mixture under an atmosphere containing substantially no halogen at a temperature of not lower than the temperature for generation of barium titanate.

Barium titanate powder and method for producing same

A thermoelectric conversion material contains a metal oxide comprising M, Mand oxygen, wherein Mis at least one selected from the group consisting of Ca, Sr and Ba and may contain an element selected from the group consisting of Li, Na, K, Mg, La, Ce, Nd, Sm, Bi and Pb, and wherein Mcomprises Cu as an essential element and may contain an element selected from the group consisting of Ti, V, Cr, Mn, Fe, Co and Ni. The mole ratio of Mto M(M/M) is 1.2 to 2.2.

Thermoelectric conversion material, method for producing the same and thermoelectric conversion device

Process for producing zirconia powder

A zirconia sintered body having high strength and high toughness is provided, and a method for producing the same is also provided. The zirconia sintered body comprising tetragonal zirconia, wherein a full width at half maximum at (111) plane of the tetragonal zirconia obtained by X-ray diffraction pattern is from 0.38 to 4 degree. A method for producing the zirconia sintered body, wherein the method comprises steps of; molding zirconia powder having an average particle diameter of from 0.1 to 0.6 &#x3bc;m, a maximum particle diameter of 5 &#x3bc;m or less and a substantially polyhedral shape, and then sintering the molded green body under the temperature of from 1200 to 1400&#xb0; C.

Zirconia sintered body and a method for producing the same

&#x3b1;-Alumina powder of fine particles having the primary particle diameters of from 10 nm to 100 nm, and of a high ratio of &#x3b1;-phase and further having capability to provide a sintered body with high density, and a method of manufacturing the &#x3b1;-alumina powder is provided. The method for manufacturing the &#x3b1;-alumina powder comprises a step of mixing an aluminum compound which is the precursor for the corresponding &#x3b1;-alumina and at least one selected from the group consisting of a titanium compound, an iron compound, a chromium compound, and &#x3b1;-alumina, and aluminum nitride, aluminum carbide and a aluminum boride as a seed crystal(s), and a step of calcining the mixture at a temperature of from 600&#xb0; C. to 1000&#xb0; C. in the presence of HCl gas in an concentration of 1% by volume to 20% by volume.

&#x3b1;-Alumina fine powder and a method of producing the same

A complex metal oxide powder composed of fine particles, each in an approximately spherical shape, is provided by a method for producing a complex metal oxide powder, which method comprises heating at least two kinds of metal salts, or a complex metal salt comprising at least two kinds of metals, to a temperature at which transition to a complex metal oxide occurs, and calcining the metal salts or the complex metal salt in an atmosphere containing a halogenated hydrogen gas.

Method for producing complex metal oxide powder

A process for producing a polycrystalline alumina sintered body which includes the steps of: subjecting alumina powder to ultrasonic irradiation, mechanical stirring not using a grinding medium, or ultrasonic irradiation and mechanical stirring not using a grinding medium, resulting in slurry dispersed in a solvent; drying and forming the slurry to produce a green body; and then sintering the green body in an air atmosphere at a temperature in the range of 1400&deg; C. to 1800&deg; C.; wherein the alumina powder has: a purity of 99.99 wt % or more and includes &agr; alumina particles having polyhedral shape, having substantially no red surface and a D/H ratio of from 0.5 or more to 3.0 or less; the number-average particle size of from 0.1 &mgr;m or more to 1.0 &mgr;m or less; and a D90/D10 ratio of 7 or less.

Alumina sintered body and process for producing the same

Alpha alumina powder having a regulated particle size, a uniform particle shape and a narrow particle size distribution and further a low halogen content is produced by calcining at least one starting material selected from transition alumina and alumina compounds in a halogen-containing atmosphere which comprises a hydrogen halide gas, a halogen gas or a mixture of a halogen gas and steam and contains at least 0.1% by volume of at least one halogen-containing gas selected from the group consisting of hydrogen halide gas and halogen gas, and removing halogen from a calcined material. The produced alpha-alumina powder is excellent in a packing property and homogeneously packed.

Method for producing &agr;-alumina powder

A process for producing &agr;-alumina containing &agr;-alumina single crystal particles characterized in that at least one of a transition alumina and transition alumina precursor is calcined in an atmosphere containing at least 1% by volume of hydrogen chloride at a temperature of not less than 600&deg; C., preferably from 600 to 1,400&deg; C., and more preferably from 800 to 1,200&deg; C. Aluminum hydroxide, alum, aluminum sulfate, etc. are used as the alumina raw material capable of being converted to transition alumina on heating. &agr;-Alumina comprising octahedral or higher polyhedral &agr;-alumina single crystal particles have a high alumina purity above a given level, are fine and homogeneous, have a narrow particle size distribution, are not agglomerated particles, and can be obtained from raw materials of various kinds, purities, shapes, sizes, and compositions.

Process for producing &agr;-alumina

A translucent alumina sintered body wherein the total content of an alkali metal element and an alkaline earth metal element is 50 ppm or less, and the linear transmittance of a light having a wavelength of 600 nm is 40% or more at a thickness of the sintered body of 0.85 mm.

Translucent alumina sintered body and a process for producing the same

Translucent alumina sintered body and production thereof

.alpha.-Alumina comprising .alpha.-alumina single crystal particles which are homogeneous containing no crystal seed inside the particles; have an octa- or higher polyhedral shape; have a D/H ratio of from 0.5 to 3.0, wherein D represents a maximum particle diameter parallel to a hexagonal lattice plane of a hexagonal close-packed lattice of the particles, and H represents a diameter perpendicular to the hexagonal lattice plane; have a number average particle diameter of more than 5 .mu.m and not more than 30 .mu.m; have a sodium content of less than 5 ppm in terms of Na.sub.2 O; and have an alumina purity of not less than 99.90% by weight. .alpha.-Alumina in a powder form composed of .alpha.-alumina single crystal particles having a high punity, a fine and uniform composition, a narrow particle size distribution, and an octa- or higher polyhedral shape which are not aggromerates. The .alpha.-alumina of the invention is useful as an abrasive, a raw material for sintered products, a raw material for a encapsulations, a raw material for ceramic filters, etc. and, owing to its high purity, particularly useful as a raw material for single crystals, e.g., yttrium aluminum garnet (YAG), sapphire, ruby, etc. and as a raw material for high purity sintered products.

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Tsukuba, Japan

Yoshio Uchida