Disclosed is a method for preparing an alumina-based solid solution ceramic powder by using an aluminum oxygen combustion synthesis water mist process, which comprises: drying raw materials and then mixing same until uniform to obtain a mixed material; loading the mixed material into a high-pressure reactor, igniting same in an oxygen-containing atmosphere, carrying out a high-temperature combustion synthesis reaction to form a high-temperature melt and then carrying out heat preservation for 1-60 s; and then opening a nozzle, ejecting the high-temperature melt through the nozzle and rapidly cooling same through a liquid phase, thus obtaining the alumina-based solid solution ceramic powder.

A ceramic composite having a phosphor particle and a coating layer on the surface of the phosphor particle, in which a matrix crystal structure of the phosphor particle and the coating layer have identical garnet structures, and the thickness of the coating layer is greater than or equal to 0.001 μm and smaller than or equal to 0.450 μm.

A method for producing a solid composition according to the present disclosure is a method for producing a solid composition that is used for forming a functional ceramic having a first crystal phase. The method for producing a solid composition includes: producing an oxide composed of a second crystal phase different from the first crystal phase; and mixing the oxide and an oxo acid compound.

An electret includes an electret layer. The electret layer is formed by subjecting a composite film in which inorganic dielectric particles are dispersed and held in a base film to a polarization treatment. The inorganic dielectric particles are mainly composed of an inorganic dielectric material having a bandgap energy of 4 eV or more.

An electret includes an electret layer. The electret layer is formed by subjecting a composite film in which inorganic dielectric particles are dispersed and held in a base film to a polarization treatment. The inorganic dielectric particles are mainly composed of an inorganic dielectric material having a bandgap energy of 4 eV or more.

Provided is a particulate phosphor including a single crystal having a composition represented by a compositional formula (Y.sub.1-x-y-zLu.sub.xGd.sub.yCe.sub.z).sub.3+aAl.sub.5−aO.sub.12 (0≤x≤0.9994, 0≤y≤0.0669, 0.001≤z≤0.004, −0.016≤a≤0.315) and a particle diameter (D50) of not less than 20 μm. Also provided is a light-emitting device including a phosphor-including member that includes the phosphor and a sealing member including a transparent inorganic material sealing the phosphor or a binder including an inorganic material binding particles of the phosphor, and a light-emitting element that emits a blue light for exciting the phosphor.

Provided is a particulate phosphor including a single crystal having a composition represented by a compositional formula (Y.sub.1-x-y-zLu.sub.xGd.sub.yCe.sub.z).sub.3+aAl.sub.5−aO.sub.12 (0≤x≤0.9994, 0≤y≤0.0669, 0.001≤z≤0.004, −0.016≤a≤0.315) and a particle diameter (D50) of not less than 20 μm. Also provided is a light-emitting device including a phosphor-including member that includes the phosphor and a sealing member including a transparent inorganic material sealing the phosphor or a binder including an inorganic material binding particles of the phosphor, and a light-emitting element that emits a blue light for exciting the phosphor.

An object is to provide a new type of near-infrared ray-emitting phosphor which exhibits excellent emission intensity. A near-infrared ray-emitting phosphor is represented by a general formula, (Y,Lu,Gd).sub.3-x-y (Ga,Al,Sc).sub.5O.sub.12:(Cr.sub.x,(Yb,Nd).sub.y) (0.05<x<0.3, 0≤y<0.3).

A polycrystalline YAG sintered body, wherein, when dimensions of a smallest rectangular solid surrounding a YAG sintered body are A mm×B mm×C mm, a maximum value (A, B, C) is 150 mm or less, a minimum value (A, B, C) is more than 20 mm and 40 mm or less, and an optical loss coefficient when light of a wavelength of 300 to 1500 nm (excluding wavelengths which result in absorption of light by an additive element) is transmitted therethrough is 0.002 cm.sup.−1 or less. Moreover, a polycrystalline YAG sintered body, wherein, when dimensions of a smallest rectangular solid surrounding a YAG sintered body are A mm×B mm×C mm, a maximum value (A, B, C) is more than 150 mm and 300 mm or less, a minimum value (A, B, C) is more than 5 mm and 40 mm or less, and an optical loss coefficient when light of a wavelength of 300 to 1500 nm (excluding wavelengths which result in absorption of light by an additive element) is transmitted therethrough is 0.002 cm.sup.−1 or less. An object of an embodiment of the present invention is to provide a large and transparent polycrystalline YAG sintered body and its production method.

A polycrystalline YAG sintered body, wherein, when dimensions of a smallest rectangular solid surrounding a YAG sintered body are A mm×B mm×C mm, a maximum value (A, B, C) is 150 mm or less, a minimum value (A, B, C) is more than 20 mm and 40 mm or less, and an optical loss coefficient when light of a wavelength of 300 to 1500 nm (excluding wavelengths which result in absorption of light by an additive element) is transmitted therethrough is 0.002 cm.sup.−1 or less. Moreover, a polycrystalline YAG sintered body, wherein, when dimensions of a smallest rectangular solid surrounding a YAG sintered body are A mm×B mm×C mm, a maximum value (A, B, C) is more than 150 mm and 300 mm or less, a minimum value (A, B, C) is more than 5 mm and 40 mm or less, and an optical loss coefficient when light of a wavelength of 300 to 1500 nm (excluding wavelengths which result in absorption of light by an additive element) is transmitted therethrough is 0.002 cm.sup.−1 or less. An object of an embodiment of the present invention is to provide a large and transparent polycrystalline YAG sintered body and its production method.