An electrostatic chuck includes a ceramic top plate layer made of a beryllium oxide material, a ceramic bottom plate layer made of a beryllium oxide material, a ceramic middle plate layer disposed between the ceramic top plate layer and the ceramic bottom plate layer, an electrode layer disposed between the ceramic top plate layer and the ceramic middle plate layer, and a heater layer disposed between the ceramic middle plate layer and the ceramic bottom plate layer. The electrode layer joins and hermetically seals the ceramic top plate layer to the ceramic middle plate layer, and the heater layer joins and hermetically seals the ceramic middle plate layer to the ceramic bottom plate layer.

A multilayer ceramic capacitor includes: a ceramic body in which dielectric layers and first and second internal electrodes are alternately stacked; and first and second external electrodes formed on an outer surface of the ceramic body and electrically connected to the first and second internal electrodes, respectively. In a microstructure of the dielectric layer, dielectric grains are divided by a dielectric grain size into sections each having an interval of 50 nm, respectively, a fraction of the dielectric grains in each of the sections within a range of 50 nm to 450 nm is within a range of 0.025 to 0.20, and a thickness of the dielectric layer is 0.8 μm or less.

Disclosed is a moderator for moderating neutrons, including a substrate and a surface treatment layer or a dry inert gas layer or a vacuum layer coated on the surface of the substrate, wherein the substrate is prepared from a moderating material by a powder sintering device through a powder sintering process from powders or by compacting powders into a block, and the moderating material includes 40% to 100% by weight of aluminum fluoride; wherein the surface treatment layer is a hydrophobic material; and the surface treatment layer or the dry inert gas layer or the vacuum layer is used for isolating the substrate from the water in the environment in which the substrate is placed. The surface treated moderator can avoid the hygroscopic or deliquescence of the moderating material during use, improve the quality of the neutron source and prolong the service life.

A dielectric material includes a perovskite as a main phase, an A site of the perovskite including at least Ba, a B site of the perovskite including at least Ti, and Eu having +2 valence and +3 valence. A ratio of +2 valence of Eu is 21% or more.

In order to provide a dielectric composition having high relative permittivity at a wide range of temperatures, the main component of a dielectric composition includes strontium and tantalum.

A dielectric composition includes a main-phase particle and segregation particles. The main-phase particle includes a main component having a perovskite crystal structure represented by a general formula of ABO.sub.3. The dielectric composition includes RA, RB, M, and Si. Each of A, B, RA, RB, and M is one or more elements selected from a specific element group. Each of an RA content C.sub.RA to the main component, an RB content C.sub.RB to the main component, an M content to the main component, and a Si content to the main component is within a predetermined range. 0.50<(α/β)/(C.sub.RA/C.sub.RB)≤1.00 is satisfied, where a is an average RA content (mol %) and f3 is an average RB content (mol %) of specific segregation particles mainly including RA, RB, Si, Ba, and Ti in the segregation particles.

A dielectric composition includes a main phase and segregation phases each including RE (at least one rare earth element). The main phase includes a main component having a perovskite crystal structure of ABO.sub.3 (A is one or more selected from Ba, Sr, and Ca, and B is one or more selected from Ti, Zr, and Hf). The segregation phases are classified into first segregation phases whose atomic ratio of Si to RE is 0 or more and 0.20 or less and second segregation phases whose atomic ratio of Si to the RE is more than 0.20. 0≤S1/S2≤0.10 is satisfied on a cross section of the dielectric composition, where S1 is an area ratio of the first segregation phases, and S2 is an area ratio of the second segregation phases. An atomic ratio of Si to RE in the second segregation phases is 0.80 or less on average.

A dielectric composition includes a main phase, first segregation phases, and second segregation phases. The main phase includes a main component having a perovskite crystal structure of ABO.sub.3 (A is one or more selected from Ba, Sr, and Ca, and B is one or more selected from Ti, Zr, and Hf). The first segregation phases include RE (one or more selected from rare earth elements), A, Si, Ti, and O. The second segregation phases include RE, A, Ti, and O and do not substantially include Si. 0.10<S2/S1≤1.50 is satisfied on a cross section of the dielectric composition, where S1 is an area ratio of the first segregation phases, and S2 is an area ratio of the second segregation phases.

A method for preparing a carbon/boron carbide composite material includes the following steps (A) providing a carbon compound, a carbon fiber, a boron compound and a binder to perform a pretreatment mixing procedure to form a precursor; (B) putting the precursor into a spray granulator for performing a granulation process and mixing the precursor to form an injection material with a uniform composition; (C) feeding the injection material into an injection molding machine for performing a compression molding process, thereby forming a carbon compound/boron compound green body; and (D) subjecting the carbon compound/boron compound green body to a two-stage heat treatment process to obtain the carbon/boron carbide composite material.

A dielectric composition includes one of BaTiO.sub.3, (Ba,Ca)(Ti,Ca)O.sub.3, (Ba,Ca)(Ti,Zr)O.sub.3, Ba(Ti,Zr)O.sub.3 and (Ba,Ca)(Ti,Sn)O.sub.3, as a main component, a first subcomponent including a rare earth element, and a second subcomponent including at least one of a variable valence acceptor element and a fixed valence acceptor element. When a sum of contents of the rare earth element is defined as DT and a sum of contents of the variable valence acceptor element and the fixed valence acceptor element is defined as AT, (DT/AT)/(Ba+Ca) satisfies more than 0.5 and less than 6.0. In addition, a multilayer electronic component including the dielectric composition is provided.