A ceramic component included in a plasma etching apparatus, wherein a surface of the ceramic component may include a base material and a composite material disposed in contact with the base material, wherein a resistivity of the ceramic component may be 10.sup.−1 Ω.Math.cm to 20 Ω.Math.cm, and wherein the base material may include a first boron carbide-based material and the composite material may include at least one selected from the group consisting of a second boron carbide-based material, a carbon-based material, and combinations thereof, is disclosed.

A zirconia powder in which when a stabilizer is Y.sub.2O.sub.3, a content thereof is 1.4 mol % or more and less than 2.0 mol %; when the stabilizer is Er.sub.2O.sub.3, a content thereof is 1.4 mol % or more and 1.8 mol % or less; when the stabilizer is Yb.sub.2O.sub.3, a content thereof is 1.4 mol % or more and 1.8 mol % or less; and when the stabilizer is CaO, a content thereof is 3.5 mol % or more and 4.5 mol % or less; and in a range of 10 nm or more and 200 nm or less in a pore distribution, a peak top diameter of a pore volume distribution is 20 nm or more and 120 nm or less, a pore volume is 0.2 ml/g or more and less than 0.5 ml/g, and a pore distribution width is 30 nm or more and 170 nm or less.

A zirconia powder containing a stabilizer, and having a specific surface area of 20 m.sup.2/g or more and 60 m.sup.2/g or less and a particle diameter D.sub.50 of 0.1 μm or more and 0.7 μm or less, in which in a range of 10 nm or more and 200 nm or less in a pore distribution based on a mercury intrusion method, a peak top diameter in a pore volume distribution is 20 nm or more and 85 nm or less, a pore volume is 0.2 ml/g or more and less than 0.5 ml/g, and a pore distribution width is 40 nm or more and 105 nm or less.

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.

The present invention relates to a negative active material for a lithium secondary battery, a preparation method therefor, and a lithium secondary battery including the same. The negative electrode active material is a negative electrode material for a secondary battery, the negative electrode active material comprising a silicon-carbon composite comprising: a core comprising crystalline carbon and silicon particles; and an amorphous carbon-containing coating layer disposed on a surface of the core, wherein the negative electrode active material comprises: silicon oxide formed on a surface of the silicon particles; and an oxide of crystalline carbon, formed on a surface of the crystalline carbon, the average particle diameter (D50) of the silicon particles having a nanometer size, the proportion of O relative to Si in the silicon oxide is 30%-50%, and the proportion of O relative to C in the oxide of the crystalline carbon is 4%-10%.

Provided is a piezoelectric ceramics having a gradual change in piezoelectric constant depending on an ambient temperature. Specifically, provided is a single-piece piezoelectric ceramics including as a main component a perovskite-type metal oxide represented by a compositional formula of ABO.sub.3, wherein an A site element in the compositional formula contains Ba and M.sub.1, the M.sub.1 being formed of at least one kind selected from the group consisting of Ca and Bi, wherein a B site element in the compositional formula contains T1 and M.sub.2, the M.sub.2 being formed of at least one kind selected from the group consisting of Zr, Sn, and Hf, wherein concentrations of the M.sub.1 and the M.sub.2 change in at least one direction of the piezoelectric ceramics, and wherein increase and decrease directions of concentration changes of the M.sub.1 and the M.sub.2 are directions opposite to each other.

In a silicon nitride substrate including a silicon nitride sintered body including silicon nitride crystal grains and a grain boundary phase, a plate thickness of the silicon nitride substrate is 0.4 mm or les, and a percentage of a number of the silicon nitride crystal grains including dislocation defect portions inside the silicon nitride crystal grains in a 50 μm×50 μm observation region of any cross section or surface of the silicon nitride sintered body is not less than 0% and not more than 20%. Etching resistance can be increased when forming the circuit board.

An abrasive particle can include a coating overlying at least a portion of a core. In an embodiment, the coating can include a first portion overlying at least a portion of the core and a second portion overlying at least a portion of the core, wherein the first portion can include a ceramic material and the second portion can include a silane or a silane reaction product. In a particular embodiment, the first portion can consist essentially of silica. In another particular embodiment, the first portion can include a surface roughness of not greater than 5 nm and a crystalline content of not greater than 60%.

A solid electrolyte which contains a garnet-type composite metal oxide phase (L) and shows an excellent lithium ion conductivity is provided. The solid electrolyte contains a garnet-type composite metal oxide phase (L) and a phase (D) different from the phase (L). The phase (L) contains Li, La, Zr, O, and Ga, and an Li site in the phase (L) is substituted with the Ga. A lattice constant of the solid electrolyte is not smaller than 12.96 Å. The phase (D) contains at least one of LiF, BaZrO.sub.3, YF.sub.3, SrF.sub.2, and ScF.sub.3.

A multilayer electronic component includes a body including a dielectric layer and an internal electrode; and an external electrode disposed on the body and connected to the internal electrode, wherein the dielectric layer includes first and second grains, wherein the first grain has a core-shell structure including a shell having an atomic ratio of 2*Sn/(Ba+Ti+Sn) or 2*Hf/(Ba+Ti+Hf) to be 1.0% or more and 5.0% or less, and a core having an atomic ratio of 2*Sn/(Ba+Ti+Sn) and 2*Hf/(Ba+Ti+Hf) to be less than 1.0%, and the second grain has an atomic ratio of 2*Sn/(Ba+Ti+Sn) and 2*Hf/(Ba+Ti+Hf) to be less than 1.0%, and wherein an area occupied by the first grain in an entire area of the first and second grains is 28.3-82.3%.