A lead-free lithium doped potassium sodium niobate piezoelectric ceramic material powdered form and having a single crystalline phase and uses thereof are described. Methods of making the said piezoelectric ceramic material are also described.

The invention relates to a copper/ceramic composite comprisinga ceramic substrate which contains aluminum oxide, a coating which lies on the ceramic substrate and which is made of copper or a copper alloy, wherein the copper or the copper alloy has a particle size number distribution with a median value d.sub.50, an arithmetic mean value d.sub.arith, and a symmetry value S(Cu)=d.sub.50/d.sub.arith; the aluminum oxide has a particle size number distribution with a median value d.sub.50, an arithmetic mean value d.sub.arith, and a symmetry value S(Al.sub.2O.sub.3)=d.sub.50/d.sub.arith; and S(Al.sub.2O.sub.3) and S(Cu) satisfy the following condition: 0.7<S(Al.sub.2O.sub.3)/S(Cu)1.4.

A precursor of an alumina sintered compact including aluminum, yttrium, and at least one metal selected from iron, zinc, cobalt, manganese, copper, niobium, antimony, tungsten, silver, and gallium. The aluminum content is 98.0% by mass or more as an oxide (Al.sub.2O.sub.3) in 100% by mass of the precursor of an alumina sintered compact; the yttrium content is 0.01 to 1.35 parts by mass as an oxide (Y.sub.2O.sub.3) based on 100 parts by mass of the content of the aluminum as an oxide; the total content of the metals selected from the foregoing group is 0.02 to 1.55 parts by mass as an oxide based on 100 parts by mass of the content of aluminum as an oxide; and the aluminum is contained as -alumina. Also disclosed is an alumina sintered compact, and a method for producing an alumina sintered compact and for producing abrasive grains.

A ferrite sintered magnet 100 comprises M-type ferrite crystal grains 4 having a hexagonal structure, two-crystal grain boundaries 6a formed between two of the M-type ferrite crystal grains 4, and multiple-crystal grain boundaries 6b surrounded by three or more of the M-type ferrite crystal grains 4. This ferrite sintered magnet 100 contains at least Fe, Ca, B, and Si, and contains B in an amount of 0.005 to 0.9 mass % in terms of B.sub.2O.sub.3, the two-crystal grain boundaries 6a and the multiple-crystal grain boundaries 6b contain Si and Ca, and in a cross-section parallel to a c-axis of the ferrite sintered magnet, when the number of multiple-crystal grain boundaries 6b having a maximum length of 0.49 to 5 m per cross-sectional area of 76 m.sup.2 is N, N is 7 or less.

A corrosion resistant member has a portion to be exposed to a corrosive gas. The portion to be exposed to the corrosive gas is formed of a ceramic sintered body. The mean width (Rsm) of profile elements of a surface of the ceramic sintered body is 25 m or less, and the ratio (Rsm/Ra) of the mean width (Rsm) of the profile elements to the arithmetic mean roughness (Ra) of the surface of the ceramic sintered body is 4,000 or less.

The present application relates to a magnesium oxide based dielectric ceramics with ultrahigh dielectric breakdown strength and a preparation method thereof. The composition of the magnesium oxide based dielectric ceramic material comprises: (1x)MgO-xAl.sub.2O.sub.3, wherein 0<x0.12 and x is a mole percentage. The material has a specific composite structure with magnesium aluminate spinel acting as a second phase surrounding a principal crystalline phase, MgO.

An aluminum nitride sintered compact containing aluminum nitride crystal grains and composite oxide crystal grains containing a rare earth element and an aluminum element, wherein a median diameter of the aluminum nitride crystal grains is 2 m or less; 10 to 200 intergrain voids having a longest diameter of 0.2 to 1 m are dispersed in a region of a cross section of 100 m in square; and the carbon atom content is less than 0.10% by mass. Also disclosed is a method of producing the aluminum nitride sintered compact.

A ceramic article includes a ceramic body including a spinel (MgAl.sub.2O.sub.4) structure, wherein a ratio of a density of the spinel structure to a theoretical density of a spinel is greater than 99.5%. A semiconductor apparatus for manufacturing a semiconductor structure includes a ceramic article including a spinel (MgAl.sub.2O.sub.4) structure, wherein a ratio of a density of the spinel structure to a theoretical density of a spinel is greater than 99.5%. A method of manufacturing a ceramic article includes providing a green body; heating the green body to a sintering temperature; compressing the green body; applying a electrical pulse to the green body; and forming a ceramic body including a spinel (MgAl.sub.2O.sub.4) structure after heating, compressing and applying the electrical pulse to the green body.

A multilayer piezoelectric ceramic is such that: its piezoelectric ceramic layers do not contain lead as a constituent element, and have a perovskite compound expressed by the composition formula Li.sub.xNa.sub.yK.sub.1-x-yNbO.sub.3 (where 0.02<0.1, 0.02<x+y1), as the primary component; and the internal electrode layers are constituted by a metal containing silver by 80 percent by mass or more, and contain ceramic grains containing the same elements found in the primary component. The multilayer piezoelectric element has a long lifespan, and whose internal electrode layers have a high content percentage of silver.

Scintillator materials based on mixed garnet compositions, as well as corresponding methods and systems, are described.