The present invention addresses the problem of providing: a porous carbon structure that has a high micropore volume and can be self-contained; a manufacturing method therefor; a positive electrode material using the same; and a battery (particularly an air battery) using the same. The present invention is a porous carbon structure that is for a positive electrode for an air battery and has voids and a skeleton formed by incorporating carbon, the porous carbon structure satisfying all of the following conditions (a) to (d). (a) The t-plot external specific surface area is within the range of 300m.sup.2/g to 1600m.sup.2/g; (b) the total volume of micropores having a diameter of lnm to 200 nm is within the range of 1.2 cm.sup.3/g to 7.0cm.sup.3/g; (c) the total volume of micropores having a diameter of lnm to 1000 nm is within the range of 2.3cm3/g to 10.0 cm.sup.3/g; and (d) the overall porosity is within the range of 80% to 99%.

A dielectric material includes a perovskite as a main phase, an A site of the perovskite including at least Ba, a B site of the perovskite including at least Ti, and Eu having +2 valence and +3 valence. A ratio of +2 valence of Eu is 21% or more.

A method for fabricating a composite useful in a white light emitting device, includes mixing a phosphor and a filler to form a mixture; sintering the mixture (e.g., using spark plasma sintering) to form a composite; and annealing the composite to reduce oxygen vacancies and improve optical properties of the composite. Also disclosed is a white light emitting device including a laser diode or light emitting diode optically pumping the phosphor in the composite to produce white light. The composite fabricated using the method (and having. e.g., at most 50% phosphor by weight) can (1) reduce an operating temperature of the phosphor by 55 degrees, (2) increase an external quantum efficiency (e.g., by at least 15%) of the white light emitting device, and (3) result in color points and quality of the white light that is equal to or improved, as compared to without the filler.

Provided is a dielectric composition exhibiting a high specific dielectric constant and a high resistivity even when fired in a reducing atmosphere. The dielectric composition contains a composite oxide having a composition represented by (Sr.sub.xBa.sub.1-x).sub.yNb.sub.2O.sub.5+y, the crystal system of the composite oxide is tetragonal, and y in the composition formula is smaller than 1.

A sintered body includes a solid solution containing cobalt and iron, with the balance being zirconia. The total content of cobalt in terms of CoO and iron in terms of Fe.sub.2O.sub.3 is more than 0.1 wt % and less than 3.0 wt %, and the proportion of cobalt regions larger than 5.5 μm.sup.2 in an elemental map obtained using an electron probe microanalyzer is 25% or less.

A method of manufacture for a carbon/carbon part including a method to remove contamination from an intermediate product of the carbon/carbon part and furnace utilizing a gaseous reducing agent hydrogen gas to reduce the contaminates, thereby causing the contaminates to transition to a gaseous state at relatively lower temperatures. A method to remove contamination from an intermediate product of the carbon/carbon part and furnace utilizing hydrogen gas to reduce the contaminates, thereby causing the contaminates to transition to a gaseous state at relatively lower temperatures.

A process for the preparation of a membrane electrode assembly comprising providing, in the following layer order, (I) a green supporting electrode layer comprising a composite of a mixed metal oxide and Ni oxide; (IV) a green mixed metal oxide membrane layer; and (V) a green second electrode layer comprising a composite of a mixed metal oxide and Ni oxide; and sintering all three layers simultaneously.

A method for manufacturing a wavelength conversion member that offers a high emission intensity and a high light conversion efficiency is provided. The method for manufacturing a wavelength conversion member includes providing a green body containing an yttrium-aluminum-garnet phosphor with a composition represented by Formula (I) below and alumina particles with an alumina purity of 99.0% by mass or more, primary-sintering the green body to obtain a first sintered body, and secondary-sintering the first sintered body by applying a hot isostatic pressing (HIP) treatment to obtain a second sintered body.

(Y.sub.1-a-bGd.sub.aCe.sub.b).sub.3Al.sub.5O.sub.12  (I)

wherein a and b satisfy 0≤a≤0.3 and 0<b≤0.022.

A manufacturing method of a silicon carbide-based honeycomb structure, including a firing step of introducing extruded honeycomb formed bodies containing a silicon carbide-based component, together with firing members into a firing furnace, and firing the honeycomb formed bodies, to manufacture the silicon carbide-based honeycomb structure, wherein the firing members are formed by using a ceramic material containing 70 wt % or more of alumina, and the firing step further includes: an inert gas supplying step of supplying an inert gas to a furnace space of the firing furnace, and a gas adding step of adding a reducing gas to the furnace space.

A method for producing a ceramic composite includes: preparing a sintered body in a plate form containing a fluorescent material having a composition of a rare earth aluminate, and aluminum oxide; and eluting the aluminum oxide from the sintered body by contacting the sintered body with a basic substance, for example, contained in an alkali aqueous solution, and the dissolution amount of the fluorescent material eluted from the sintered body in the step of eluting the aluminum oxide is 0.5% by mass or less based on an amount of the fluorescent material contained in the sintered body as 100% by mass.