A refractory, coarse ceramic product including at least one granular refractory material, has an open porosity of between 22 and 45 vol.-%, in particular of between 23 and 29 vol.-%, and a grain structure of the refractory material, wherein the medium grain size fraction with grain sizes of between 0.1 and 0.5 mm is 10 to 55 wt.-%, in particular 35 to 50 wt.-%, and wherein the remainder of the grain structure is a finest grain fraction with grain sizes of up to 0.1 mm and/or coarse-grain fraction with grain sizes of more than 0.5 mm.

A refractory, coarse ceramic product including at least one granular refractory material, has an open porosity of between 22 and 45 vol.-%, in particular of between 23 and 29 vol.-%, and a grain structure of the refractory material, wherein the medium grain size fraction with grain sizes of between 0.1 and 0.5 mm is 10 to 55 wt.-%, in particular 35 to 50 wt.-%, and wherein the remainder of the grain structure is a finest grain fraction with grain sizes of up to 0.1 mm and/or coarse-grain fraction with grain sizes of more than 0.5 mm.

Porous aluminum-containing ceramic bodies are treated to form acicular mullite crystals onto the surfaces of their pores. The crystals are formed by contacting the body with a fluorine-containing gas or a source of both fluorine and silicon atoms to form fluorotopaz at the surface of the pores, and then decomposing the fluorotopaz to form acicular mullite crystals. This process allows the surface area of the ceramic body to be increased significantly while retaining the geometry (size, shape, general pore structure) of the starting body. The higher surface area makes the body more efficient as a particulate filter and also allows for easier introduction of catalytic materials.

Porous aluminum-containing ceramic bodies are treated to form acicular mullite crystals onto the surfaces of their pores. The crystals are formed by contacting the body with a fluorine-containing gas or a source of both fluorine and silicon atoms to form fluorotopaz at the surface of the pores, and then decomposing the fluorotopaz to form acicular mullite crystals. This process allows the surface area of the ceramic body to be increased significantly while retaining the geometry (size, shape, general pore structure) of the starting body. The higher surface area makes the body more efficient as a particulate filter and also allows for easier introduction of catalytic materials.

In one embodiment, a method includes forming a powder having a composition with the formula: A.sub.hB.sub.iC.sub.jO.sub.12, where h is 3±l 0%, i is 2=10%, j is 3±10%, A includes one or more rare earth elements, B includes aluminum and/or gallium, and C includes aluminum and/or gallium. The method additionally includes consolidating the powder to form an optically transparent ceramic, and applying at least one thermodynamic process condition during the consolidating to reduce oxygen and/or thermodynamically reversible defects in the ceramic. In another embodiment, a scintillator includes (Gd.sub.3-a-cY.sub.a)x(Ga.sub.5-bAl.sub.b).sub.yO.sub.12D.sub.c, where a is from about 0.05-2, b is from about 1-3, x is from about 2.8-3.2, y is from about 4.8-5.2, c is from about 0.003-0.3, and D is a dopant, and where the scintillator is an optically transparent ceramic scintillator having physical characteristics of being formed from a ceramic powder consolidated in oxidizing atmospheres.

Provided are a member for plasma processing device which has an excellent plasma resistance and improved adhesion strength of a film to a base material, and a plasma processing device provided with the same. A member for plasma processing device includes: a base material containing a first element which is a metal element or a metalloid element; a film containing a rare-earth element oxide, or a rare-earth element fluoride, or a rare-earth element oxyfluoride as a major constituent, the film being located on the base material; and an amorphous portion containing the first element, a rare earth element, and at least one of oxygen and fluorine, the amorphous portion being interposed between the base material and the film.

[Objective] To provide a ceramic emitter that exhibits high radiation intensity and excellent wavelength selectivity.

[Solution] A ceramic emitter includes a polycrystalline body that has a garnet structure represented by a compositional formula R.sub.3Al.sub.5O.sub.12 (R: rare-earth element) or R.sub.3Ga.sub.5O.sub.12 (R: rare-earth element) and has pores with a porosity of 20-40%. The pores have a portion where the pores are connected to one another but not linearly continuous, inside the polycrystalline body.

A ceramic structure of the present disclosure is provided with: a first member made of a single crystal of sapphire or an yttrium aluminum composite oxide; and a second member in contact with the first member, the second member being made of ceramic containing an aluminum oxide or an yttrium aluminum composite oxide as a principal component, wherein, of crystal grains constituting the second member, contact grains of the second member, which are grains in contact with the first member, include a first curved surface part that is convex toward the first member.

A ceramic structure of the present disclosure is provided with: a first member made of a single crystal of sapphire or an yttrium aluminum composite oxide; and a second member in contact with the first member, the second member being made of ceramic containing an aluminum oxide or an yttrium aluminum composite oxide as a principal component, wherein, of crystal grains constituting the second member, contact grains of the second member, which are grains in contact with the first member, include a first curved surface part that is convex toward the first member.

A method for manufacturing a ceramic article including (i) a step of irradiating a powder mainly containing a ceramic material with an energy beam to sinter or melt and solidify the powder into a solidified portion, wherein the step is repeated a predetermined number of times to sequentially bond the resulting solidified portions together to obtain a ceramic modeling object, (ii) a step of allowing the shaped ceramic object to absorb a metal component-containing liquid that contains inorganic particles containing a metal element; and (iii) a step of heating the shaped ceramic object that has absorbed the metal component-containing liquid.