Provided are gallium nitride particles that have a low oxygen content and a high moldability and allow a gallium nitride sputtering target having a high density and a high strength to be produced. By causing a mixed powder of gallium oxide and gallium nitride to react at a temperature of 1000-1100° C. such that an ammonia reaction amount per hour is 1 or more times (by mole) an amount of gallium charged, gallium nitride particles are obtained of which an oxygen content is 1 atm % or less, an average particle size of primary particles is 5 μm or more, and a particle size of a range of 10 area % from smallest particles of a particle size distribution (10% particle size) is 3 μm or less.

A corrosion-resistant member may include alumina ceramics containing α-alumina and anorthite. The alumina ceramics may contain 0.4% by mass or more of Ca and Si in total in terms of CaO and SiO.sub.2, respectively, and a mass ratio of CaO/SiO.sub.2 may fall within a range of 0.5 to 2. Moreover, a ratio B/A of X-ray diffraction peak intensity B for (004) plane of the anorthite to X-ray diffraction peak intensity A for (104) plane of the α-alumina in a surface of the alumina ceramics, may be 0.01 or more.

A method of making a scintillator material includes forming a dried ceramic composition into a ceramic body with a garnet crystal formula (Gd.sub.3-x-zY.sub.x)Ce.sub.z(Ga.sub.5-yAl.sub.y)O.sub.12, where x is about 0 to about 2, y is about 0 to about 5, and z is about 0.001 to about 1.0. The ceramic body is sintered to form a sintered ceramic body. The sintered ceramic body is surrounded by a powder mixture that includes a garnet powder. The density of the sintered ceramic body is increased by applying an increased temperature and isostatic pressure to form the scintillator material.

A dielectric composition including a complex oxide represented by a general formula of A.sub.aB.sub.bC.sub.4O.sub.15+α as a main component, in which “A” at least includes Ba, “B” at least includes Zr, “C” at least includes Nb, “a” is 3.05 or more, and “b” is 1.01 or more.

A transparent ceramic material is manufactured by molding a source powder into a compact, the source powder comprising a rare earth oxide consisting of at least 40 mol % of terbium oxide and the balance of another rare earth oxide, and a sintering aid, sintering the compact at a temperature T (1,300 C.T1,650 C.) by heating from room temperature to T1 (1200 C.T1T) at a rate of at least 100 C./h, and optionally heating from T1 at a rate of 1-95 C./h, and HIP treating the sintered compact at 1,300-1,650 C. The ceramic material has improved diffuse transmittance in the visible region and functions as a magneto-optical part in a broad visible to NIR region.

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 method for producing a ceramic complex includes: preparing a raw material mixture that contains 5% by mass or more and 40% by mass or less of first rare earth aluminate fluorescent material particles containing an activating element and a first rare earth element different from the activating element, 0.1% by mass or more and 32% by mass or less of oxide particles containing a second rare earth element, and the balance of aluminum oxide particles, relative to 100% by mass of the total amount of the first rare earth aluminate fluorescent material particles, the oxide particles, and the aluminum oxide particles; preparing a molded body of the raw material mixture; and obtaining a sintered body by calcining the molded body in a temperature range of 1,550 C. or higher and 1,800 C. or lower.

A dielectric ceramic composition includes a main component of a perovskite type compound represented by a general formula of ABO.sub.3, in which A is an element in an A-site, B is an element in a B-site, and O is an oxygen element. A includes Ba. A further includes at least one of Ca and Sr. B includes Ti. A sintered-body lattice volume obtained by X-ray diffraction method is 64.33 .sup.3 or below.

An oxide sintered body containing indium, hafnium, tantalum, and oxygen as constituent elements, in which when indium, hafnium, and tantalum are designated as In, Hf, and Ta, respectively, the atomic ratio of Hf/(In+Hf+Ta) is equal to 0.002 to 0.030, and the atomic ratio of Ta/(In+Hf+Ta) is equal to 0.0002 to 0.013.

A transparent ceramic material is manufactured by molding a source powder into a compact, the source powder comprising a rare earth oxide consisting of at least 40 mol % of terbium oxide and the balance of another rare earth oxide, and a sintering aid, sintering the compact at a temperature T (1,300 C.T1,650 C.) by heating from room temperature to T1 (1200 C.T1T) at a rate of at least 100 C./h, and optionally heating from T1 at a rate of 1-95 C./h, and HIP treating the sintered compact at 1,300-1,650 C. The ceramic material has improved diffuse transmittance in the visible region and functions as a magneto-optical part in a broad visible to NIR region.