A lead-free piezoelectric composition including, as a main component, an alkali niobate perovskite-type oxide containing Mn, Ti, and Sc, which composition has a ratio of Sc content to Ti content of 0.004 or more and 8 or less.

A cubic boron nitride sintered material includes: 40 to 80 volume % of cubic boron nitride grains; and 20 to 60 volume % of a binder phase, wherein an average grain size d of the cubic boron nitride grains is 0.1 to 3 m, the binder phase includes at least one selected from a second group consisting of a simple substance of one element selected from a first group, an alloy consisting of two or more elements selected from the first group, and an intermetallic compound consisting of two or more elements selected from the first group, or at least one selected from a fourth group consisting of a first compound and a solid solution originated from the first compound, and in a cross section of the cubic boron nitride sintered material, a variation coefficient Z of an area ratio of the cubic boron nitride grains is 0.25 or less.

To provide a Tb-containing rare earth-aluminum garnet ceramic which has a Verdet constant similar to that of a TGG single crystal used in an isolator, has an insertion loss and extinction ratio equal to or greater than those of a TGG single crystal, generates less heat when a high-power laser is applied thereto, and is unlikely to cause a thermal lens effect or thermal birefringence. The present invention relates to: a Tb-containing rare earth-aluminum garnet ceramic including a garnet polycrystal represented by the compositional formula (Tb.sub.zRe.sub.1-x).sub.3(Al.sub.ySc.sub.1-y).sub.5O.sub.12 wherein Re is at least one element selected from a group consisting of Y and Lu, x=1.0-0.5, and y=1.0-0.6, and including Si and at least one element selected from a group consisting of Ca and Mg; a method for producing same; and an isolator device obtained using the ceramic.

To provide a sliding member having improved wear resistance, and a method of manufacturing the sliding member. A femoral head ball according to an aspect of the present disclosure includes a composite ceramic containing alumina and at least one oxide other than alumina. A surface roughness Ra of the sliding surface when the femoral head ball slides against a constituent member constituting an artificial joint is not more than 0.01 m. The sliding surface includes a plurality of recessed portions each having an opening diameter of not more than 2 m.

Provided are alumina particles containing molybdenum and with their shape controlled. The alumina particles contain phosphorus and molybdenum. The alumina particles are preferably plate-like or card house-like. The phosphorus is preferably unevenly distributed in surface layers of the alumina particles. Also provided are a resin composition containing the alumina particles and a resin, a molded body made by molding the resin composition, and a method for producing the alumina particle including a step of firing the aluminum compound in the presence of a molybdenum compound and a phosphorous compound.

Provided is a piezoelectric single crystal-polycrystal ceramic composite, a method of manufacturing the same, and piezoelectric and dielectric application components using the piezoelectric single crystal-polycrystal ceramic composite. The piezoelectric single crystal-polycrystal ceramic composite shows that complexation is carried out by the optimization of a ratio between grain size distributions of a piezoelectric single crystal and polycrystal ceramic grains, and a volume ratio of the contained piezoelectric single crystal so that mass production simultaneously with excellent piezoelectric characteristics of the piezoelectric single crystal can be realized, and the cost of production can be reduced, so the piezoelectric single crystal-polycrystal ceramic composite can be applied to piezoelectric and dielectric application components, like ultrasonic transducers, piezoelectric actuators, piezoelectric sensors, dielectric capacitors, electric field-generating transducers, and electric field and vibration-generating transducers, using the piezoelectric single crystal-polycrystal ceramic composite, and the piezoelectric single crystal-polycrystal ceramic composite can enhance piezoelectric characteristics and competitiveness in prices.

A multilayer ceramic electronic component includes a dielectric layer including first crystal grains and second crystal grains, the first crystal grains having a perovskite structure represented by a general formula ABO.sub.3 and having a core portion containing molybdenum and a shell portion, the shell portion covering the core portion and containing a rare earth element and manganese, the second crystal grains including, as a main component, a barium titanate-based composite oxide and having an elemental ratio of barium to titanium of 0.70 or less, internal electrode layers sandwiching the dielectric layer, and external electrodes electrically connected to the internal electrode layers, respectively.

The present invention relates to the fields of heat storage and thermally conductive materials, and discloses a highly thermally conductive heat storage material, a preparation method therefor, and the application thereof, and a composition for preparing a highly thermally conductive heat storage material and the application thereof. The highly thermally conductive heat storage material comprises 11-41 wt % of a carbonaceous part and 59-89 wt % of a graphitic part; for the carbonaceous part, L.sub.c>18 nm, L.sub.a>35 nm, d.sub.002<0.3388 nm, and the degree of graphitization is 60% to 95%; for the graphitic part, L.sub.c>50 nm; L.sub.a>80 nm; d.sub.002<0.3358 nm, and the degree of graphitization is 95% to 100%. The highly thermally conductive heat storage material comprises a carbonaceous part with a specific structure and a graphitic part with a specific structure, and the heat storage material obtained thereby possesses high thermal conductivity and high compressive strength. Meanwhile, the preparation process of the highly thermally conductive heat storage material is simple and cost-effective.

A preparation method of a multi-bullet-resistant ceramic and a bulletproof insert plate are provided; the ceramic is made by sintering silicon carbide and/or boron carbide and the sintering is one or more of high-temperature sintering, reactive sintering, hot-pressed sintering, or pressureless sintering. The average grain size of the ceramic is 200 to 380 m, the Vickers hardness is 23.5 GPa to 34 GPa, and the compression strength is 2200 MPa to 3100 MPa. The back bulge generated during bullet penetration can be effectively lowered on the precondition of ensuring the bulletproof insert plate is not penetrated by the bullet, fully satisfying the multi-faceted bulletproof requirements of the new-generation protective insert plate.