A thermoelectric conversion material formed of a sintered body containing magnesium silicide as a main component contains 0.5 mass % or more and 10 mass % or less of aluminum oxide. The aluminum oxide is distributed at a crystal grain boundary of the magnesium silicide.

A composite sintered body is a ceramic composite sintered body which includes metal oxide which is a main phase, and silicon carbide which is 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 a proportion of the crystal grains of the silicon carbide dispersed in the crystal grains of the metal oxide is 25% or more in an area ratio with respect to a total crystal grains of the silicon carbide.

A ceramic composite can include a first ceramic phase and a second ceramic phase. The first ceramic phase can include a silicon carbide. The second phase can include a boron carbide. In an embodiment, the silicon carbide in the first ceramic phase can have a grain size in a range of 0.8 to 200 microns. The first phase, the second phase, or both can further include a carbon. In another embodiment, at least one of the first ceramic phase and the second ceramic phase can have a median minimum width of at least 5 microns.

A cubic boron nitride sintered body has between 50% and 75% cubic boron nitride by volume and between 25% and 50% binder phase by volume, and inevitable impurities. The binder phase contains an Al compound and a Zr compound. The Al compound contains Al and one or more of N, O and B; and the Zr compound contains Zr and one or more of C, N, O and B. At a polished surface of the cubic boron nitride sintered body, 40% or more of the Zr compounds satisfy the ratio 0.25n/N0.8, where: N represents the number of line segments drawn radially at equal intervals from a center of gravity of a given Zr compound to a boundary with a non-Zr compound; and n represents the number among those N line segments which intersect a boundary between the given Zr compound and cubic boron nitride.

A sintered material includes a first material and a second material, the first material being partially stabilized ZrO.sub.2 having a crystal grain boundary or crystal grain in which 5 to 90 volume % of Al.sub.2O.sub.3 is dispersed with respect to a whole of the first material, the second material including at least one of SiAlON, silicon nitride and titanium nitride, the sintered material including 1 to 50 volume % of the first material.

A sintered compact magnesium oxide target for sputtering having a purity of 99.99 wt % or higher, a density of 3.58 g/cm.sup.3 or higher, and a transparency 10% or more. A sintered compact magnesium oxide target for sputtering having a purity of 99.99 wt % or higher, a density of 3.58 g/cm.sup.3 or higher, and an average crystal grain size of 50 m or more.

This invention provides a transparent magnetooptical material that is suitable for use in a magnetooptical device such as an optical isolator. Said magnetooptical material comprises either a transparent ceramic consisting primarily of a complex oxide that can be represented by formula (1) or a single crystal of such a complex oxide. Said magnetooptical material does not absorb fiber-laser light in the 0.9-1.1 m wavelength range, does not cause heat lensing, and has a higher Verdet constant than TGG crystals, with a Verdet constant of at least 0.14 min/(Oe.Math.cm) at a wavelength of 1,064 nm.
Tb.sub.2R.sub.2O.sub.7(1)
(In formula (1), R represents one or more elements selected from among the group consisting of silicon, germanium, titanium, tantalum, tin, hafnium, and zirconium (but not silicon only, germanium only, or tantalum only)).

Setter plates are fabricated from Li-stuffed garnet materials having the same, or substantially similar, compositions as a garnet Li-stuffed solid electrolyte. The Li-stuffed garnet setter plates, set forth herein, reduce the evaporation of Li during a sintering treatment step and/or reduce the loss of Li caused by diffusion out of the sintering electrolyte. Li-stuffed garnet setter plates, set forth herein, maintain compositional control over the solid electrolyte during sintering when, upon heating, lithium is prone to diffuse out of the solid electrolyte.

The present invention relates to a light-transmitting ceramic sintered body which contains air voids having pore diameters of 1 m or more but less than 5 m at a density within the range of from 10 voids/mm.sup.3 to 4,000 voids/mm.sup.3 (inclusive), while having a closed porosity of from 0.01% by volume to 1.05% by volume (inclusive). With respect to this light-transmitting ceramic sintered body, a test piece having a thickness of 1.90 mm has an average transmittance of 70% or more in the visible spectrum wavelength range of 500-900 nm, and the test piece having a thickness of 1.90 mm has a sharpness of 60% or more at a comb width of 0.5 mm.

Provided is a transparent rare earth aluminum garnet ceramic that has a highlight transmission rate and can be mass produced. The transparent rare earth aluminum garnet ceramic is represented by general formula R.sub.3Al.sub.5O.sub.12 (R is an element selected from the group consisting of rare earth elements having an atomic number of 65 to 71) and includes Si and Y as sintering aids, or is represented by general formula R.sub.3Al.sub.5O.sub.12 (R is an element selected from the group consisting of rare earth elements having an atomic number of 65 to 70) and includes Si and Lu as sintering aids.