Provided are a barium titanate-based piezoelectric ceramics having satisfactory piezoelectric performance and a satisfactory mechanical quality factor (Q.sub.m), and a piezoelectric element using the same. Specifically provided are a piezoelectric ceramics, including: crystal particles; and a grain boundary between the crystal particles, in which the crystal particles each include barium titanate having a perovskite-type structure and manganese at 0.04% by mass or more and 0.20% by mass or less in terms of a metal with respect to the barium titanate, and the grain boundary includes at least one compound selected from the group consisting of Ba.sub.4Ti.sub.12O.sub.27 and Ba.sub.6Ti.sub.17O.sub.40, and a piezoelectric element using the same.

Provided is a barium compound structure including: a plurality of first compound particles containing a barium compound that is crystalline and is different from barium sulfate; a binding part covering a surface of each of the plurality of first compound particles and containing barium sulfate that is crystalline; and a plurality of second compound particles containing a compound that contains silicon. The first compound particles are bound through at least one of the binding part or the plurality of second compound particles.

Provided is a crystalline silicon carbide fiber containing silicon carbide, boron nitride, and zirconium carbide and having a content of Si of 64% by weight or more and a content of C of 28% by weight or more, in which the average particle size of SiC crystal grains is 100 nm or more.

An oxide electrolyte sintered body with high lithium ion conductivity and a method for producing the same, which can obtain the oxide electrolyte sintered body with high lithium ion conductivity by sintering at lower temperature than ever before. The method for producing an oxide electrolyte sintered body may comprise the steps of: preparing crystal particles of a garnet-type ion-conducting oxide which comprises Li, H, at least one kind of element L selected from the group consisting of an alkaline-earth metal and a lanthanoid element, and at least one kind of element M selected from the group consisting of a transition element that can be 6-coordinated with oxygen and typical elements belonging to the Groups 12 to 15, and which is represented by a general formula (Li.sub.x−3y−z,E.sub.y,H.sub.z)L.sub.αM.sub.βO.sub.γ (where E is at least one kind of element selected from the group consisting of Al, Ga, Fe and Si, 3≦x−3y−z≦7, 0≦y<0.22, 0<z≦2.8, 2.5≦α≦3.5, 1.5≦β≦2.5, and 11≦γ≦13); preparing a lithium-containing flux; and sintering a mixture of the crystal particles of the garnet-type ion-conducting oxide and the flux by heating at 400° C. or more and 650° C. or less.

A particulate material having a body including a dopant contained in the body, the dopant is non-homogenously distributed throughout the body and the body has a maximum normalized dopant content difference of at least 35%.

A ceramic material includes of β-sialon (Si.sub.(6-z)Al.sub.zO.sub.zN.sub.(8-z)), polytype 15R, an intergranular phase, and yttrium. The polytype 15R includes twin grains.

A composite polycrystal contains polycrystalline diamond formed of diamond grains that are directly bonded mutually, and non-diamond carbon dispersed in the polycrystalline diamond, and has a concentration of contained hydrogen of less than or equal to 1000 ppm.

A composite polycrystal contains polycrystalline diamond formed of diamond grains that are directly bonded mutually, and non-diamond carbon dispersed in the polycrystalline diamond, and has a concentration of contained hydrogen of greater than 1000 ppm and less than or equal to 20000 ppm.

A composite ceramic including: a lithium garnet major phase; and a grain growth inhibitor minor phase, as defined herein. Also disclosed is a method of making composite ceramic, pellets and tapes thereof, a solid electrolyte, and an electrochemical device including the solid electrolyte, as defined herein.

A multilayer ceramic capacitor that includes a ceramic body including a stack of a plurality of dielectric layers and a plurality of first and second internal electrodes; and first and second external electrodes provided at each of both end faces of the ceramic body. Each of the plurality of dielectric layers contain Ba, Ti, P and Si. The plurality of dielectric layers include an outer dielectric layer located on an outermost side in the stacking direction; an inner dielectric layer located between the first and second internal electrodes; and a side margin portion in a region where the first and second internal electrodes do not exist. In at least one of the outer dielectric layer, the inner dielectric layer and the side margin portion, the P and the Si segregate in at least one of grain-boundary triple points of three ceramic particles.