An alumina sintered body having a low dielectric loss tangent and a method for manufacturing the alumina sintered body are provided. An alumina sintered body contains Al.sub.2O.sub.3 99.50 mass % or more, and 99.95 mass % or less and sodium and silicon, wherein at a surface layer A in any given cross-section and a central portion B of the cross-section in a depth direction from the surface layer A, a concentration ratio of sodium to silicon in the surface layer A is smaller than the concentration ratio of sodium to silicon at the central portion B.

An aluminum nitride-based sintered compact includes: aluminum nitride crystal particles containing Mg; composite oxide containing a rare earth element and Al, the composite oxide having a garnet crystal structure; and composite oxynitride containing Mg and Al. Particles of the composite oxide and particles of the composite oxynitride are interspersed between the aluminum nitride crystal particles. The composite oxide may include Y. A content of Mg in the aluminum nitride crystal particles may fall in a range of 0.1 mol % or more and 1.0 mol % or less, based on a total of all metal elements contained in the aluminum nitride crystal particles taken as 100 mol %. A semiconductor holding device includes the aluminum nitride-based sintered compact; and an electrostatic adsorptive electrode.

A process for manufacturing ceramic-metal composite material, comprises dissolving ceramic powder into water to obtain an aqueous solution of ceramic; mixing metal powder having a multimodal particle size where largest particle size is one fourth of the minimum dimension of a device, with the aqueous solution of ceramic to obtain a powder containing ceramic precipitated on the surface of metal particles; mixing the powder containing ceramic precipitated on the surface of the metal particles, with ceramic powder having a particle size below 50 μm, to obtain a powder mixture; adding saturated aqueous solution of ceramic to the powder mixture to obtain an aqueous composition containing ceramic and metal; compressing the aqueous composition to form a disc of ceramic-metal composite material containing ceramic and metal; and removing water from the ceramic-metal composite material; wherein ceramic content of the disc is 10 vol-% to 35 vol-%. Alternatively, ceramic-ceramic composite material may be manufactured.

A ZrO.sub.2—Al.sub.2O.sub.3-based ceramic sintered compact containing tetragonal ZrO.sub.2 particles having a crystallite size of from 5 to 20 nm as a main component and having an α-Al.sub.2O.sub.3 crystallite size of not greater than 75 nm and a relative density of not less than 99% can be produced by preparing a Y.sub.2O.sub.3 partially stabilized ZrO.sub.2—Al.sub.2O.sub.3-based powder having a molar ratio (mol %) of zirconia (ZrO.sub.2) and yttria (Y.sub.2O.sub.3) of from 96.5:3.5 to 97.5:2.5 and a mass ratio (mass %) of ZrO.sub.2 containing Y.sub.2O.sub.3 and alumina (Al.sub.2O.sub.3) of from 85:15 to 75:25, molding this powder by cold isostatic pressing, and then performing sintering to a high density by microwave sintering for 45 to 90 min in an inert gas atmosphere at 1200 to 1400° C. When performing microwave sintering, a heating rate is preferably from 5 to 20° C./min up to 600° C. and from 50 to 150° C./min at 600° C. or higher.

A method of preparing a ceramic fabric for use in a ceramic matrix composite includes arranging a plurality of tows to form a ceramic fabric with a first inter-tow spacing, applying a binder material to the ceramic fabric, and applying pressure to the ceramic fabric to form a pressure stabilized ceramic fabric. Each of the plurality of tows of the ceramic fabric has a first thickness, and each of at least a subset of the plurality of tows of the pressure stabilized ceramic fabric has a second thickness less than the first thickness.

A titanium-containing calcium hexaaluminate material and preparation method thereof is disclosed. The technical solution is: using 60˜80 wt % alumina micro powder, 5˜20 wt % calcium-containing micro powder, 10˜20 wt % titania micro powder and 1˜10 wt % manganese oxide micro powder as raw materials, blending the raw materials evenly in a planetary ball mill to obtain a blend, machine pressing the blend at 100˜200 MPa to obtain a green body, drying the green body at 110˜200° C. for 12˜36 h, and incubating the dried green body at 1500˜1800° C. for 1˜8 h to obtain the titanium-containing calcium hexaaluminate material. The present disclosure has low cost and simple process, and the prepared titanium-containing calcium hexaaluminate material has the characteristics of good chemical stability, high thermal shock resistance and strong melt resistance to titanium-aluminum alloy.

Provided is a zirconia sintered body having both high translucency and high strength. The zirconia sintered body includes crystal grains that include a cubic domain and a tetragonal domain, wherein a stabilizer and lanthanum is dissolved as a solid solution therein. The sintered body can be obtained by a manufacturing method including: a mixing step of obtaining a mixed powder by mixing a zirconia source, a stabilizer source, and a lanthanum source; a molding step of obtaining a green body by molding the obtained mixed powder; a sintering step of obtaining a sintered body by sintering the obtained green body at a sintering temperature of 1650° C. or higher; and a temperature lowering step of lowering the temperature from the sintering temperature to 1000° C. at a temperature lowering rate exceeding 1° C./min.

The present application provides vanadium dioxide doped with Ti, or vanadium dioxide further doped with other atoms selected from the group of W, Ta, Mo, and Nb. The vanadium dioxide of the present application is excellent in moisture resistance and in which deterioration of endothermic characteristics due to moisture is suppressed.

A composite polycrystal includes: a polycrystalline diamond phase including a plurality of diamond particles; and non-diamond phases composed of non-diamond carbon. The non-diamond phases are distributed in the polycrystalline diamond phase. An average value of projected area equivalent circle diameters of the non-diamond phases is not more than 1000 nm.

[Object] Provided are a Zn—Sn—O-based oxide sintered body which is used as a sputtering target or a tablet for vapor deposition and which is resistant to crack formation and the like during film formation, and a method for producing the same. [Solving means] The oxide sintered body is characterized in that tin is contained with an atomic ratio of Sn/(Zn+Sn) being 0.01 to 0.6, an average crystal particle diameter of the sintered body is 4.5 μm or less, and a degree of orientation represented by I.sub.(222)/[I.sub.(222)+I.sub.(400)] is 0.52 or more, where I.sub.(222) and I.sub.(400) represent integrated intensities of the (222) plane and the (400) plane of a Zn.sub.2SnO.sub.4 phase measured by X-ray diffraction using the CuKα radiation. The oxide sintered body has an improved mechanical strength, so that the oxide sintered body is resistant to breakage during processing of the sintered body and also is resistant to breakage and crack formation during film formation of transparent conductive films when used as a sputtering target or a tablet for vapor deposition.