National Institute for Materials Science

National Institute for Research in Inorganic Materials

National Institute for Researches in Inorganic Materials

Nissan Motor Company Limited

Japan Science and Technology Agency

Denki Kagaku Kogyo Kabushiki Kaisha

Mamoru Mitomo

Naoto Hirosaki

Rong-Jun Xie

Toshiyuki Nishimura

Yoshinobu Yamamoto

Hideki Hirotsuru

Masakazu Komatsu

Motohide Ando

Kyouta Ueda

Tadashi Endo

Youngwook Kim

Hideyuki Emoto

Masahiro Ibukiyama

Toshimori Sekine

Yusuke Moriyoshi

Yoshizo Inomata

Takamichi Kobayashi

Hongliang He

Koji Kimoto

Kazuyoshi Shimakage

Hisayuki Suematsu

Nobuyuki Kuramoto

Shinji Hirai

Toshiaki Osaka

Toshikazu Sakai

Yoichiro Uemura

Yuji Yoshioka

Masahiro Central Research Institute Ibukiyama

Hideyuki Central Research Institute Emoto

A fluorophor includes: &#x3b1;-type sialon crystal which is expressed by a general formula: (Li, Eu)(SiAl)(ON), wherein x1 is an amount of solid solution of Li in a sialon unit cell, and x2 is an amount of solid solution of Eu in the sialon unit cell, wherein the parameters x1, x2, m, and n satisfy: 1.6&#x2266;x1&#x2266;2.4 (1), 0.001&#x2266;x2&#x2266;0.4 (2), 1.8&#x2266;m&#x2266;2.4 (3), 0.8&#x2266;n&#x2266;1.2 (4), wherein the &#x3b1;-type sialon crystal emits fluorescence with a peak in a wavelength region of from 550 nm to 575 nm upon irradiation of an excitation source.

Fluorophor and method for production thereof and illuminator

A fluorophor which comprises as a main component, an &#x3b1; type sialon crystal containing at least Li, A element (wherein A represents one or more elements selected from among Mn, Ce, Pr, Nd, Sm, Eu, Tb, Dy, Er, Tm and Yb), M element (wherein M represents one or more metal elements except Li and the A element), Si, Al, oxygen and nitrogen. The fluorophor has an a type sialon crystal structure which is represented by the general formulae: (Li, A, M)(SiAl)(ON) 1.2&#x2266;x1&#x2266;2.4 (1) 0.001&#x2266;x2&#x2266;0.4 (2) and 0&#x2266;x3&#x2266;1.0 (3), and has a luminescence peak at a wavelength in the range of 400 to 700 nm. The above phosphor is reduced in the lowering of brightness, and can be suitably used for a white LED and the like.

According to the invention, a highly crystalline &#x3b1;-sialon is synthesized to emit highly intense light and a white LED showing an excellent color rendering characteristic is provided by shifting emitted light to the short wavelength side (blue shift). Such an &#x3b1;-sialon is designed so as to be expressed by general formula (Li, Ca, Eu) (SiAl) (ON) wherein the numerical ranges of x, y, z, m and n are respectively 0&#x3c;x&#x3c;2.0, 0&#x3c;y&#x3c;2.0, 0&#x3c;z&#x2266;0.5 (provided that 0.3&#x2266;x+y+z&#x2266;2.0), 0&#x3c;m&#x2266;4.0 and 0&#x3c;n&#x2266;3.0.

Lithium-containing sialon phosphor and method of manufactring the same

An &#x3b1;-sialon is offered which is represented by general formula: (M1)(M2)(Si, Al)(O, N)(wherein M1 represents one or more elements selected from the group which consists of Li, Mg, Ca, Y and lanthanoid (except La and Ce) and M2 represents one or more elements selected from the group which consists of Ce, Pr, Eu, Tb, Yb and Er and wherein 0.3&#x3c;X+Y&#x3c;1.5 and 0&#x3c;Y&#x3c;0.7), the &#x3b1;-sialon containing from 30 ppm to 1% of fluorine as an impurity. By making primary particles of the &#x3b1;-sialon 1 to 10 &#x3bc;m in average particle size, an &#x3b1;-sialon phosphor can be obtained reproducibly, stably and in a large quantity. Especially, if containing 30 to 200 ppm of impurity fluorine, the &#x3b1;-sialon phosphor can exhibit an excellent emission characteristic as a white fluorescent matter.

&#x3b1;-Sialon, &#x3b1;-sialon phosphor and method for producing the same

A fluorophor comprising, as a main component, an &#x3b1;-type sialon crystal which contains at least an A element (wherein A represents one or more elements selected from among Mn, Ce, Pr, Nd, Sm, Eu, Tb, Dy, Er, Tm and Yb), an M element (wherein M represents one or more elements selected from among Li, Na, Mg, Ca, Y, La, Gd and Lu), Si, Al, oxygen and nitrogen, and is represented by the general formula: (M, A)(SiAl)(ON) (1) m=&#x3b4;&#xd7;x+&#x3b4;&#xd7;y (2) 0.2&#x2266;x&#x2266;2.4 (3) 0.001&#x2266;y&#x2266;0.4 (4) and 0.5&#xd7;m&#x3c;n&#x2266;4 (5). The fluorophor is reduced in the lowering of brightness, and is useful for a white color LED and the like.

The present invention provides a lanthanum sulfide or cerium sulfide sintered compact usable as a thermoelectric conversion material having a high Seebeck coefficient. The sintered compact has a chemical composition of LaSor CeS, and a crystal structure consisting of a mixture of beta and gamma phases having a Seebeck coefficient higher than that of the crystal structure otherwise being in gamma single-phase. The sintered compact is produced by preparing a beta-phase LaSor alpha-phase CeSpowder of raw material having a high purity with a suppressed carbon impurity concentration and a given range of oxygen concentration, charging the raw material into a carbon die having an inner surface covered with an h-BN applied thereon, and hot-pressing the charged material under vacuum to form a mixture of beta and gamma phases having a high Seebeck coefficient.

Sintered compact of lanthanum sulfide or cerium sulfide and method for preparing the same

An oxynitride phosphor activated by a rare earth element, represented by the formula Ca Si Al O N : Eu Dy , wherein stabilizing metal (Ca) is substituted partially by Eu or Eu and Dy where 0.3<x<1.5, 0.01<y<0.7, 0&lE;z<0.1, 0.6<m<3.0 and 0<n<1.5.

Oxynitride phosphor activated by a rare earth element, and sialon type phosphor

A silicon nitride sintered product comprising silicon nitride grains and a grain boundary phase, wherein the grain boundary phase consists essentially of a single phase of a Lu Si O N crystal phase, and the composition of the silicon nitride sintered product is a composition in or around a triangle ABC having point A: Si N , point B: 28 mol % SiO -72 mol % Lu O and point C: 16 mol % SiO -84 mol % Lu O , as three apexes, in a ternary system phase diagram of a Si N &mdash;SiO &mdash;Lu O system. Also disclosed is a silicon nitride sintered product comprising silicon nitride grains and a grain boundary phase of an oxynitride, wherein the composition of the sintered product is a composition in a triangle having point A: Si N , point B: 40 mol % SiO -60 mol % Lu O and point C: 60 mol % SiO -40 mol % Lu O , as three apexes, in a ternary system phase diagram of a Si N &mdash;SiO &mdash;Lu O system.

Silicon nitride sintered products and processes for their production

A sialon type phosphor in the form of a powder comprising at least 40 wt % of &agr;-sialon represented by the formula (Ca ,M )(Si,Al) (O,N) (where M is at least one metal selected from the group consisting of Eu, Tb, Yb and Er, 0.05<(x&plus;y)<0.3, 0.02<x<0.27 and 0.03<y<0.3) and having a structure such that Ca sites of Ca-&agr;-sialon are partially substituted by other metal M, at most 40 wt % of &bgr;-sialon, and at most 30 wt % of unreacted silicon nitride.

A high pressure phase spinel type sialon represented by the chemical formula Si Al O N (0<x&lE;4.2), and a high pressure phase spinel type silicon oxynitride represented by the chemical formula Si O N (&boxH;Si N .xSiO , 0<x<1). Methods for their production by instantaneous pressing by means of an impulse wave.

Spinel type sialon, spinel type silicon oxynitride and methods for producing their powders

A superplastic silicon nitride sintered body which is a sintered body of silicon nitride and which has superplasticity such that when a compression or tensile stress of from 30 to 2000 kg/cm.sup.2 is applied thereto at a temperature within a range of from 1350.degree. to 1650.degree. C., it deforms at a deformation rate of from 10.sup.-4 /sec to 10.sup.-1 /sec.

Superplastic silicon nitride sintered body

A superplastic silicon carbide sintered body which comprises at least 85 wt % and at most 98 wt % of silicon carbide grains and more than 2 wt % and less than 15 wt % of a grain boundary phase and which has a relative density of at least 95%, wherein the silicon carbide grains have an average grain size of at most 0.3 .mu.m, the amount of grains having grain sizes exceeding 0.5 .mu.m is at most 3 wt %, and the deformation rate of the sintered body is at least 10.sup.-4 /sec under a compression or tensile stress of from 50 to 2,000 kg/cm.sup.2 within a temperature range of from 1,600.degree. to 1,800.degree. C.

Superplastic silicon carbide sintered body

A high strength and toughness .beta.-silicon nitride sintered body suitable for the material of a variety of structural parts. The sintered body contains .beta.-silicon nitride (Si.sub.3 N.sub.4) in an amount not less than 95% by weight of total silicon nitride; oxygen in a total amount not more than 3% by weight of the sintered body; and columnar grains each of which has a diameter not less than 5 .mu.m and an aspect ratio not less than 5, the columnar grains being in an amount not less than 0.5% by volume of total of raw materials in the sintered body; the sintered body having a bulk density not less than 96% of a theoretical density. Such a sintered body is produced by a method comprising the following steps in the sequence set forth: preparing powder of a starting material including .beta.-silicon nitride in an amount not less than 80% by weight of the starting material; adding oxide of at least one element selected from the group IIIa of the periodic table of elements in an amount ranging from 0.2% to 6% by weight (as a sintering assistant) to the starting material powder to form a mixture powder; compacting the mixture powder to form a compact; firing the compact under a nitrogen gas pressure ranging from 1 to 500 atm. at a temperature ranging from 1700.degree. to 2100 .degree. C. to form the sintered body; and continuing the firing step until a bulk density of the sintered body reaches a value not less than 96% of a theoretical density of the sintered body.

.beta.-silicon nitride sintered body

A high strength and toughness .beta.-silicon nitride sintered body suitable for the material of a variety of structural parts. The sintered body contains .beta.-silicon nitride (Si.sub.3 N.sub.4) in an amount not less than 95% by weight of total silicon nitride; oxygen in a total amount not more than 3% by weight of the sintered body; and columnar grains each of which has a diameter not less than 5 .mu.m and an aspect ratio not less than 5, the columnar grains being in an amount not less than 0.5% by volume of total of raw materials in the sintered body; the sintered body having a bulk density not less than 96% of a theoretical density. Such a sintered body is produced by a method comprising the following steps in the sequence set forth: preparing powder of a starting material including .beta.-silicon nitride in an amount not less than 80% by weight of the starting material; adding oxide of at least one element selected from the group IIIa of the periodic table of elements in an amount ranging from 0.2% to 6% by weight (as a sintering assistant) to the starting material powder to form a mixture powder; compacting the mixture powder to form a compact; firing the compact under a nitrogen gas pressure ranging from 1 to 500 atm. at a temperature ranging from 1700.degree. to 2100.degree. C. to form the sintered body; and continuing the firing step until a bulk density of the sintered body reaches a value not less than 96% of a theoretical density of the sintered body.

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Ibaraki, Japan

Mamoru Mitomo