Abstract: A free-standing membrane electrolyte electrode assembly (ESC) comprises an electrolyte, an anode electrode formed at one end face of the electrolyte, and a cathode electrode formed at the other. The electrolyte is a single crystal having a surface along with oxide ions move or a direction in which the ions move or a polycrystal oriented along a surface along which oxide ions move or in a direction in which the ions move. The surface or the direction is parallel to the thickness direction. The thickness of the electrolyte is 50 to 800 ?m and the quotient of the division of the total thickness of the anode electrode and the cathode electrode by the thickness of the electrolyte is 0.1 or less,. The thickness of the ESC is 1 mm or less.

Abstract: An electrolyte-electrode assembly (MEA) includes: an electrolyte; an anode side electrode and a cathode side electrode formed so as to sandwich the electrolyte via intermediate layers. The anode side electrode has a thickness set to 1 ?m, for example. A method for manufacturing the electrolyte-electrode assembly, i.e., the MEA includes a step for forming the anode side electrode by sputtering.

Abstract: An oxide single crystal having a composition represented by RExSi6O1.5x+12 (RE: La, Ce, Pr, Nd, or Sm, x: 8 to 10) is grown by using the Czochralski method such that the crystal growth orientation coincides with the c-axis direction. The solidification rate (the weight of the grown crystal÷the weight of the charged raw material) in the crystal growth is less than 45%.

Abstract: An electrolyte-electrode assembly (MEA) includes: an electrolyte; an anode side electrode and a cathode side electrode formed so as to sandwich the electrolyte via intermediate layers. The anode side electrode has a thickness set to 1 ?m, for example. A method for manufacturing the electrolyte-electrode assembly, i.e., the MEA includes a step for forming the anode side electrode by sputtering.

Abstract: A free-standing membrane electrolyte electrode assembly (ESC) comprises an electrolyte, an anode electrode formed at one end face of the electrolyte, and a cathode electrode formed at the other. The electrolyte is a single crystal having a surface along with oxide ions move or a direction in which the ions move or a polycrystal oriented along a surface along which oxide ions move or in a direction in which the ions move. The surface or the direction is parallel to the thickness direction. The thickness of the electrolyte is 50 to 800 ?m, and the quotient of the division of the total thickness of the anode electrode and the cathode electrode by the thickness of the electrolyte is 0.1 or less. The thickness of the ESC is 1 mm or less.

Abstract: An La2O3 powder and an SiO2 powder are mixed with each other, and then heated. By heating, a porous material of LaXSi6O1.5X+12 (8?X?10) as a composite oxide is produced. Subsequently, the porous material is pulverized to obtain a powder, and the powder is added to a solvent to prepare a slurry. The slurry is solidified in a magnetic field to prepare a compact. After that, the compact is sintered, and an oxide ion conductor is obtained thereby.

Abstract: An oxide single crystal having a composition represented by RExSi6O1.5x+12 (RE: La, Ce, Pr, Nd, or Sm, x: 8 to 10) is grown by using the Czochralski method such that the crystal growth orientation coincides with the c-axis direction. The solidification rate (the weight of the grown crystal÷the weight of the charged raw material) in the crystal growth is less than 45%.

Abstract: An electrolyte is single crystal composed of La9.33Si6O26 in which the crystal is oriented in the c-axis, and the c-axis is in the thickness direction of the electrolyte. In the electrolyte, the oxide ion is preferentially migrated in the thickness direction. That is, the oxide ion conduction exhibits anisotropy. Isotropic conductive layers composed of YDC, in which the oxide ion conduction exhibits isotropy and the oxide ion conductivity is lower than that of the electrolyte, are provided between the electrolyte and an anode and a cathode.

Abstract: An La2O3 powder and an SiO2 powder are mixed with each other, and then heated. By heating, a porous material of LaXSi6O1.5X+12 (8?X?10) as a composite oxide is produced. Subsequently, the porous material is pulverized to obtain a powder, and the powder is added to a solvent to prepare a slurry. The slurry is solidified in a magnetic field to prepare a compact. After that, the compact is sintered, and an oxide ion conductor is obtained thereby.

Abstract: An La2O3 powder and an SiO2 powder are mixed with each other, and then heated. By heating, a porous material of LaXSi6O1.5X+12 (8?X?10) as a composite oxide is produced. Subsequently, the porous material is pulverized to obtain a powder, and the powder is added to a solvent to prepare a slurry. The slurry is solidified in a magnetic field to prepare a compact. After that, the compact is sintered, and an oxide ion conductor is obtained thereby.

Abstract: A lanthanum oxide (La2O3) powder, a germanium oxide (GeO2) powder, and a strontium carbonate (SrCO3) powder are mixed in a ratio so that a composition of the obtained composite oxide LalXm(AO4)6?n(ZO4)nOp satisfies 8?l+m<10, 0?m?2, 0?n?2 and 0?p?2. Thenafter, the materials are formed and sintered to prepare an oxide ion conductor. The crystalline structure of LalXm(AO4)6?n(ZO4)nOp belongs to the apatite type structure. The conduction of oxide ion occurs when O2? 14 occupying the 2a site of the apatite type structure moves along the c-axis direction.

Abstract: An electrolyte is single crystal composed of La9.33Si6O26 in which the crystal is oriented in the c-axis, and the c-axis is in the thickness direction of the electrolyte. In the electrolyte, the oxide ion is preferentially migrated in the thickness direction. That is, the oxide ion conduction exhibits anisotropy. Isotropic conductive layers composed of YDC, in which the oxide ion conduction exhibits isotropy and the oxide ion conductivity is lower than that of the electrolyte, are provided between the electrolyte and an anode and a cathode.

Abstract: An La2O3 powder and an SiO2 powder are mixed with each other, and then heated. By heating, a porous material of LaXSi6O1.5X+12 (8≦X≦10) as a composite oxide is produced. Subsequently, the porous material is pulverized to obtain a powder, and the powder is added to a solvent to prepare a slurry. The slurry is solidified in a magnetic field to prepare a compact. After that, the compact is sintered, and an oxide ion conductor is obtained thereby.

Abstract: A lanthanum oxide (La2O3) powder, a germanium oxide (GeO2) powder, and a strontium carbonate (SrCO3) powder are mixed in a ratio so that a composition of the obtained composite oxide LalXm(AO4)6−n(ZO4)nOp satisfies 8≦l+m<10, 0≦m≦2, 0≦n≦2 and 0≦p≦2. Thenafter, the materials are formed and sintered to prepare an oxide ion conductor. The crystalline structure of LalXm(AO4)6−n(ZO4)nOp belongs to the apatite type structure. The conduction of oxide ion occurs when O2− 14 occupying the 2a site of the apatite type structure moves along the c-axis direction.

Abstract: A composite powder having a specific surface area of 7 m.sup.2 /g or more is produced by mixing a silicon powder with a carbonaceous powder and a sintering aid powder, and heat-treating the resultant mixed powder in a nitrogen-containing atmosphere at a temperature of 1,450.degree. C. or lower thereby nitriding and carbonizing silicon in the mixed powder. The temperature elevation speed in the heat treatment for nitriding and carbonizing is less than 2.degree. C./minute at least in a range from a temperature at which the nitriding and carbonizing of silicon starts to take place to a temperature at which the composite powder is kept for nitriding and carbonizing of silicon. The composite sintered body is produced by sintering such a composite powder at a temperature of 1,600.degree. C. to 2,200.degree. C.

Abstract: A reinforced molded body of ceramic, which is to be fired, is produced by adding ceramic fibers to a matrix of ceramic. The ceramic fibers are composed of silicon, nitrogen, oxygen, and carbon, the carbon and the oxygen having a total content of at most 10 weight % and having respective contents at a ratio ranging from 0.08 to 2.

Abstract: A composite sintered body of silicon carbide and silicon nitride having a nano-composite structure in which fine SiC particles are dispersed in Si.sub.3 N.sub.4 particles and grain boundaries and fine Si.sub.3 N.sub.4 particles are dispersed in SiC particles is produced by (a) adding at least one sintering aid, boron and carbon to a mixed powder of silicon carbide and silicon nitride to form a green body, the sintering aid being (i) Al.sub.2 O.sub.3 or AlN and/or (ii) at least one oxide of an element selected from Groups 3A and 4A of the Periodic Table, and (b) sintering the green body by HIP or by a high-temperature normal sintering method.

Abstract: A composite sintered body of silicon nitride and silicon carbide is manufactured by sintering a composite powder or green body of silicon nitride and silicon carbide in a nitrogen gas atmosphere. The composite powder having a percentage of .alpha.-silicon nitride which is at least 30% based on all silicon nitride is produced by mixing a silicon powder with a carbonaceous powder and a sintering aid powder, and heat-treating the resultant mixed powder in a nitrogen-containing atmosphere at a temperature of 1,450.degree. C. or lower thereby nitriding and carbonizing silicon contained in the mixed powder to produce a composite powder, a temperature elevation speed being less than 2.degree. C./minute. The composite green body having a percentage of .alpha.

Abstract: A sintered composite body of silicon nitride and silicon carbide is manufactured by mixing a silicon powder with a carbonaceous powder and a sintering additive, producing a mixture, molding the mixture into a molded body, heat-treating the molded body in an atmosphere containing a nitrogen gas for thereby simultaneously nitriding and carbonizing silicon contained in the molded body, and subsequently firing the molded body in a nitrogen gas atmosphere. A composite powder of silicon nitride and silicon carbide which is produced by simultaneously nitriding and carbonizing silicon contained in the molded body has a content of .alpha.-type silicon nitride which is at least 30% of all silicon nitride in the composite powder. To produce such a composite powder, a silicon powder is mixed with a carbonaceous powder and a sintering additive, producing a mixture, and the mixture is heat-treated in an atmosphere containing a nitrogen gas at a temperature of at most 1450.degree. C.

Abstract: A silicon nitride sintered body formed by sintering a mixture of silicon nitride powder mixed with a combined sintering aid of aluminum nitride powder and a powder of at least one rare earth oxide selected from the group consisting of Ce.sub.2 O.sub.3, Pr.sub.2 O.sub.3, Nd.sub.2 O.sub.3, Dy.sub.2 O.sub.3, Ho.sub.2 O.sub.3, Er.sub.2 O.sub.3, Tm.sub.2 O.sub.3, Yb.sub.2 O.sub.3 and Lu.sub.2 O.sub.3. Another sintered body is a composite sintered body of silicon nitride and silicon carbide formed by sintering a mixture of silicon nitride, silicon carbide, aluminum nitride and at least one rare earth oxide selected from the group consisting of Ce.sub.2 O.sub.3, Pr.sub.2 O.sub.3, Nd.sub.2 O.sub.3, Ho.sub.2 O.sub.3, Er.sub.2 O.sub.3, Tm.sub.2 O.sub.3, Yb.sub.2 O.sub.3 and Lu.sub.2 O.sub.3.