A phosphor plate including: a complex containing an α-sialon phosphor and a sintered body containing spinel represented by a general formula M.sub.2xAl.sub.4-4xO.sub.6-4x (where M represents at least one of Mg, Mn, and Zn, and 0.2<x<0.6). In addition, there is provided a light emitting device including: a group III nitride semiconductor light emitting element; and the phosphor plate provided on one surface of the group III nitride semiconductor light emitting element. Further, there is provided a method for manufacturing the phosphor plate.

A member for a plasma processing device of the present disclosure is a member for a plasma processing device made of ceramics and having a shape of a cylindrical body with a through hole in an axial direction. The ceramics is mainly composed of aluminum oxide, and has a plurality of crystal grains and a grain boundary phase that is present between the crystal grains. An inner peripheral surface of the cylindrical body has an arithmetic average roughness Ra of 1 μm or more and 3 μm or less, and an arithmetic height Rmax of 30 μm or more and 130 μm or less.

Provided is a dielectric ceramic composition including a first component and a second component, wherein the first component comprises an oxide of Ca of 0.00 mol % to 35.85 mol % an oxide of Sr of 0.00 mol % to 47.12 mol %, an oxide of Ba of 0.00 mol % to 51.22 mol %, an oxide of Ti of 0.00 mol % to 17.36 mol %, an oxide of Zr of 0.00 mol % to 17.36 mol %, an oxide of Sn of 0.00 mol % to 2.60 mol %, an oxide of Nb of 0.00 mol % to 35.32 mol %, an oxide of Ta of 0.00 mol % to 35.32 mol %, and an oxide of V of 0.00 mol % to 2.65 mol %, and the second component includes at least (a) an oxide of Mn of 0.005% by mass to 3.500% by mass and (b) an oxide of Cu and/or an oxide of Ru.

A dielectric composition includes dielectric particles and first segregations. The dielectric particles each include a perovskite compound represented by ABO.sub.3 as a main component. The first segregations each include Ba, Ti, Si, Ni, and O.

A ceramic electronic device includes a multilayer structure in which each of a plurality of dielectric layers and each of a plurality of internal electrode layers are alternately stacked, a main component of the plurality of dielectric layers being a ceramic having a perovskite structure expressed by a general formula ABO.sub.3. At least one of crystal grains of the plurality of dielectric layers has a core-shell structure. A dispersion of atomic displacement amounts between B site atoms and oxygen atoms of a shell of the core-shell structure is larger than a dispersion of atomic displacement amounts between B site atoms and oxygen atoms of a core of the core-shell structure.

Embodiments relate to a method for fabricating a sintered sodium-ion material. The method involves mixing a parent phase sodium-ion compound with a secondary transient phase to form a powder mixture. The method involves applying pressure and heat above a melting point or boiling point of the secondary transient phase to drive dissolution at particle contacts and subsequent precipitation at newly formed grain boundaries. The method involves generating a sintered sodium-ion material with >90% relative density.

A plasma processing device member according to the disclosure includes a base material and a film formed of a rare-earth element oxide, or a rare-earth element fluoride, or a rare-earth element oxyfluoride, or a rare-earth element nitride, the film being disposed on at least part of the base material. The film includes a surface to be exposed to plasma, the surface having an arithmetic mean roughness Ra of 0.01 μm or more and 0.1 μm or less, the surface being provided with a plurality of pores, and a value obtained by subtracting an average equivalent circle diameter of the pores from an average distance between centroids of adjacent pores is 28 μm or more and 48 μm or less. A plasma processing device according to the disclosure includes the plasma processing device member described above.

A dielectric composition includes dielectric particles and first segregations. The dielectric particles each include a perovskite compound represented by ABO.sub.3 as a main component. The first segregations each include at least Ba, P, and O. A molar ratio (Ba/Ti) of Ba to Ti in the first segregations is 1.20 or more.

A dielectric composition includes dielectric particles and first segregations. The dielectric particles each include a perovskite compound represented by ABO.sub.3 as a main component. The first segregations each include at least Ba, V, and O. A molar ratio (Ba/Ti) of Ba to Ti detected in the first segregations is 1.20 or more.

A dielectric composition includes dielectric particles, grain boundary phases, and segregations. The dielectric particles each include a perovskite compound represented by ABO.sub.3 as a main component. The grain boundary phases are located between the dielectric particles. The segregations exist in a part of the grain boundary phases and include at least Al, Si, and O. A molar ratio (Al/(Al+Si)) of an Al content to a total content of Al and Si in the segregations is 0.45 or more and 0.75 or less.