A heat-resistant member (1) according to the present disclosure contains alumina as a main component, and magnesium aluminate and boron. The content percentage of the magnesium aluminate at the surface is higher than the content percentage of the magnesium aluminate in a surface layer section located directly below the surface.

The invention relates to a process for the preparation of a dental restoration, in which an oxide ceramic material is (a) subjected to at least one heat treatment, and (b) cooled, wherein the cooling comprises (b1) a first cooling step with the cooling rate T1 and (b2) a second cooling step with the cooling rate T2 and wherein the absolute value of the cooling rate T2 is less than the absolute value of the cooling rate T1.

The invention relates to a process for the preparation of a dental restoration, in which an oxide ceramic material is (a) subjected to at least one heat treatment, and (b) cooled, wherein the cooling comprises (b1) a first cooling step with the cooling rate T1 and (b2) a second cooling step with the cooling rate T2 and wherein the absolute value of the cooling rate T2 is less than the absolute value of the cooling rate T1.

A sinterable compound may comprise one or more Ga-alkali metal alloys (and/or one or more Hg-alkali metal amalgams) and one or more filler materials (e.g., one or more dielectric materials). To form a dielectric article or other article, the compound may be formed into a desired shape. Raising the temperature of the compound initiates an exothermic reaction of alkali metal and water and causes the filler materials to self-sinter.

A sinterable compound may comprise one or more Ga-alkali metal alloys (and/or one or more Hg-alkali metal amalgams) and one or more filler materials (e.g., one or more dielectric materials). To form a dielectric article or other article, the compound may be formed into a desired shape. Raising the temperature of the compound initiates an exothermic reaction of alkali metal and water and causes the filler materials to self-sinter.

Provided is alumina material comprising alumina and zirconium, wherein in a radial distribution function obtained by Fourier-transforming an extended X-ray absorption fine structure (EXAFS) spectrum of a K absorption edge of the zirconium in the alumina material, the value of I.sub.B/I.sub.A is 0.5 or less where I.sub.A is a maximum intensity among the intensities of peaks present at 0.1 nm to 0.2 nm, and I.sub.B is a maximum intensity among the intensities of peaks present at 0.28 nm to 0.35 nm.

Provided is alumina material comprising alumina and zirconium, wherein in a radial distribution function obtained by Fourier-transforming an extended X-ray absorption fine structure (EXAFS) spectrum of a K absorption edge of the zirconium in the alumina material, the value of I.sub.B/I.sub.A is 0.5 or less where I.sub.A is a maximum intensity among the intensities of peaks present at 0.1 nm to 0.2 nm, and I.sub.B is a maximum intensity among the intensities of peaks present at 0.28 nm to 0.35 nm.

Sintered product having a relative density of greater than 90%, with, to more than 80% of the volume thereof, a stack of flat ceramic platelets, the assembly of the platelets having a mean thickness of less than 3 μm, having a width of greater than 50 mm, and including more than 20% of alumina, as a percentage on the basis of the weight of the product. The width of the product is the largest dimension measured in the plane in which the length of the product is measured, along a direction perpendicular to the direction of the length. The length of the product is the largest dimension thereof in a plane parallel to the general plane in which the platelets extend.

A piezoelectric ceramic, which does not contain lead as a constituent element, is characterized in that: its primary component is a perovskite compound expressed by the composition formula (Bi.sub.0.5−x/2Na.sub.0.5−x/2Ba.sub.x)(Ti.sub.1−yMn.sub.y)O.sub.3 (where 0.01≤x≤0.25, 0.001≤y≤0.020); and the coefficient of variation (CV) in grain size among the grains contained therein is 35 percent or lower. The piezoelectric ceramic presents an improved dielectric loss tangent tan δ.

A piezoelectric ceramic, which does not contain lead as a constituent element, is characterized in that: its primary component is a perovskite compound expressed by the composition formula (Bi.sub.0.5−x/2Na.sub.0.5−x/2Ba.sub.x)(Ti.sub.1−yMn.sub.y)O.sub.3 (where 0.01≤x≤0.25, 0.001≤y≤0.020); and the coefficient of variation (CV) in grain size among the grains contained therein is 35 percent or lower. The piezoelectric ceramic presents an improved dielectric loss tangent tan δ.