An optically clear resin for additive manufacturing includes an optically clear ceramic precursor having a pre-defined refractive index. Each molecule of the ceramic precursor has at least two photopolymerizable functional groups, at least one of the photopolymerizable functional groups being functionalized with a refractive index-tuning group thereby causing the ceramic precursor to have the pre-defined refractive index.

A silicon nitride-based sintered body containing silicon nitride-based grains, which are silicon nitride grains or sialon grains. In the silicon nitride-based sintered body, when the size of each silicon nitride-based grain is represented by its maximum grain size, the ratio of the number of silicon nitride-based grains having a maximum grain size of 1 μm or less to the number of the entire silicon nitride-based grains is 70% or higher. Furthermore, in the distribution profile of no. % of silicon nitride-based grains with respect to maximum grain size, the maximum value of no. % (i.e., maximum no. %) of silicon nitride-based grains is 15 no. % or higher. Also disclosed is a cutting insert, which is formed of the silicon nitride-based sintered body.

A radio-frequency (RF) power variable capacitor capable of operating at, at least, 50 watts in the MHz range. The capacitor has a composite HDK-NDK ceramic dielectric. The HDK (high dielectric constant) component comprises an active matrix of barium strontium titanate, for example. Acoustic resonances are reduced or eliminated by the addition of a metal or metalloid oxide such as magnesium borate (NDK—low dielectric constant), which acts as an acoustic resonance reduction agent (ARRA) in the RF power domain. The acoustic resonances which previously occurred under bias voltage 500 V or 1100 V in prior art RF power variable capacitors are eliminated by the addition of the ARRA.

A corrosion-resistant ceramic of the present disclosure contains yttrium zirconium oxide as a main component and has a plurality of open pores. The difference between an average value of inter-centroid distances of the open pores and an average value of diameters of the open pores is 50 μm or greater.

A ceramic complex including a first crystal phase containing a first rare earth aluminate fluorescent material containing an activating element and a first rare earth element that is different from the activating element, and a second crystal phase containing aluminum oxide, having a content of the first crystal phase in a range of 5% by volume or more and 40% by volume or less and a content of the second crystal phase in a range of 57% by volume or more and 95% by volume or less based on a total amount of the ceramic complex, having an average value of a second crystal diameter of the second crystal phase measured under the particular measurement condition of 12 μm or less, and having a QD value of 0.5 or less expressed by QD=(D.sub.75−D.sub.25)/(D.sub.75+D.sub.25), wherein D.sub.25 and D.sub.75 are defined in the disclosure.

A dielectric composition and a multilayer capacitor including the same are provided. The dielectric composition includes a BaTiO.sub.3-base main component, a first subcomponent including an Nb component and a Gd component, a second subcomponent including an Mg component, and a third subcomponent including a Ba component and a Ca component. The first subcomponent is included in an amount of 4 moles or less per 100 moles of the main component. In the first subcomponent, a molar content of Nb and a molar content of Gd satisfy 0.33≤Nb/Gd, and in the third subcomponent, a molar content of Ba and a molar content of Ca satisfy 0.2≤Ca/(Ba+Ca).

A multilayer electronic component includes a body including a plurality of dielectric layers, wherein, wherein a central portion of the capacitance formation portion is Aa, a boundary portion of the capacitance formation portion, adjacent to the cover portions, is Ab, a dielectric grain size corresponding to the top 50% of dielectric grains, in order of enlargement, from the smallest grain size, among a plurality of dielectric grains included in Aa, is D50a, and a dielectric grain size corresponding to the top 50% of dielectric grains, in order of enlargement, from the smallest grain size, among a plurality of dielectric grains included in Ab, is D50b, D50a satisfies 190 nm or less and D50b satisfies 120 nm or greater.

Disclosed are a dielectric ceramic includes a plurality of crystal grain bulks including a ceramic, and a grain boundary between the plurality of crystal grain bulks, wherein a dopant is segregated in the grain boundary.

A cubic boron nitride sintered material includes: more than 80 volume % and less than 100 volume % of cubic boron nitride grains; and more than 0 volume % and less than 20 volume % of a binder phase. The binder phase includes: at least one selected from a group consisting of a simple substance, an alloy, and an intermetallic compound selected from a group consisting of a group 4 element, a group 5 element, a group 6 element in a periodic table, aluminum, silicon, cobalt, and nickel. A dislocation density of the cubic boron nitride grains is more than or equal to 1×10.sup.15/m.sup.2 and less than or equal to 1×10.sup.17/m.sup.2.

A ceramic composite sintered body, including: a metal oxide as a main phase, and silicon carbide as a sub-phase, in which crystal grains of the silicon carbide are dispersed in crystal grains of the metal oxide and at crystal grain boundaries of the metal oxide, and an average crystal grain size of the silicon carbide dispersed at the crystal grain boundaries of the metal oxide is 0.30 μm or less.