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 cubic boron nitride sintered material tool contains a plurality of cBN grains. cBN grains located on a surface of the cutting edge contain a cubic boron nitride phase, and a hexagonal boron nitride phase. When a ratio I.sub.π*/I.sub.σ* between an intensity of a π* peak derived from a π bond of hBN in the hexagonal boron nitride phase and an intensity of a σ* peak derived from a σ bond of hBN in the hexagonal boron nitride phase and a σ bond of cBN in the cubic boron nitride phase is determined by measuring an energy loss associated with excitation of K-shell electrons of boron, the ratio I.sub.π*/I.sub.σ* of the cBN grain on the surface of the cutting edge is 0.1 to 2, and the ratio I.sub.π*/I.sub.σ* of the cBN grain at a depth position of 5 μm from the surface of the cutting edge is 0.001 to 0.1.

A piezoelectric material composition, a method of manufacturing the same, a piezoelectric device, and apparatus including the piezoelectric device. The piezoelectric device may include a piezoelectric device layer including a first material and a second material surrounded by the first material, a first electrode portion disposed at a first surface of the piezoelectric device layer, and a second electrode portion disposed at a second surface of the piezoelectric device layer opposite to the first surface, wherein the piezoelectric device layer comprises a piezoelectric material composition represented by Chemical Formula 1: 0.96(Na.sub.aK.sub.1-a)(Nb.sub.b(T.sub.1-b))O.sub.3-(0.04-x)MZrO.sub.3-x(Bi.sub.cAg.sub.1-c)ZrO.sub.3+d mol % NaNbO.sub.3, wherein T is Sb or Ta, M is Sr, Ba or Ca, a is 0.4≤a≤0.6, b is 0.90≤b≤0.98, c is 0.4≤c≤0.6, d is 0≤d≤5.0, and x is 0≤x≤0.04 and wherein T is Sb or Ta and M is Sr, Ba, or Ca.

A piezoelectric thin film 3 contains a metal oxide, the metal oxide contains bismuth, potassium, titanium, iron and element M, the element M is at least one of magnesium and nickel, at least a part of the metal oxide is a crystal having a perovskite structure, and a (001) plane, a (110) plane or a (111) plane of the crystal is oriented in a normal direction dn of the surface of the piezoelectric thin film 3.

A grain-oriented M-type hexagonal ferrite has the formula MeFe.sub.12O.sub.19, and a dopant effective to provide planar magnetic anisotropy and magnetization in a c-plane, or a cone anisotropy, in the hexagonal crystallographic structure wherein Me is Sr.sup.+, Ba.sup.2+ or Pb.sup.2+, and wherein greater than 30%, preferably greater than 80%, of c-axes of the ferrite grains are aligned perpendicular to the c-plane.

An oxide superconductor according to an embodiment includes an oxide superconducting layer includes a single crystal having a continuous perovskite structure containing at least one rare earth element selected from the group consisting of yttrium, lanthanum, neodymium, samarium, europium, gadolinium, terbium, dysprosium, holmium, erbium, thulium, ytterbium, and lutetium, barium, and copper, containing praseodymium in a part of the site of the rare earth element in the perovskite structure, and having a molar ratio of praseodymium of 0.00000001 or more and 0.2 or less with respect to the sum of the at least one rare earth element and praseodymium; fluorine in an amount of 2.0×10.sup.15 atoms/cc or more and 5.0×10.sup.19 atoms/cc or less; and carbon in an amount of 1.0×10.sup.17 atoms/cc or more and 5.0×10.sup.20 atoms/cc or less.

Provided is a boron nitride sintered body including boron nitride particles and pores, the boron nitride sintered body having a sheet shape and a thickness of less than 2 mm. Provided is a method for manufacturing a boron nitride sintered body, the method including a sintering step of molding and heating a blend containing a boron carbonitride powder and a sintering aid to obtain a sheet-shaped boron nitride sintered body including boron nitride particles and pores, in which a thickness of the boron nitride sintered body obtained in the sintering step is less than 2 mm.

Provided is a boron nitride sintered body including boron nitride particles and pores, in which a compressive elastic modulus is 1 GPa or more. Provided is a method for manufacturing a boron nitride sintered body, the method including: a nitriding step of firing a boron carbide powder in a nitrogen atmosphere to obtain a fired product containing boron carbonitride; and a sintering step of molding and heating a blend containing the fired product and a sintering aid to obtain the boron nitride sintered body including boron nitride particles and pores, in which the sintering aid contains a boron compound and a calcium compound, and the blend contains 1 to 20 parts by mass of the boron compound and the calcium compound in total with respect to 100 parts by mass of the fired product.

Provided is a method for manufacturing a composite body, the method including: a nitriding step of firing a boron carbide powder in a nitrogen atmosphere to obtain a fired product containing boron carbonitride; a sintering step of molding and heating a blend containing the fired product and a sintering aid to obtain a boron nitride sintered body including boron nitride particles and pores; and an impregnating step of impregnating the boron nitride sintered body with a resin composition, the composite body having the boron nitride sintered body and a resin filled in at least some of the pores of the boron nitride sintered body.

Provided is a boron nitride sintered body including: a plurality of coarse particles each having a length of 20 μm or more; and fine particles smaller than the plurality of coarse particles, in which, when viewed in a cross-section, the plurality of coarse particles intersect with each other. Provided is a method for manufacturing a boron nitride sintered body, the method including: a raw material preparation step of firing a mixture containing boron carbonitride and a boron compound in a nitrogen atmosphere to obtain lump boron nitride having an average particle diameter of 10 to 200 μm; and a sintering step of molding and heating a blend containing the lump boron nitride and a sintering aid to obtain a boron nitride sintered body including coarse particles each having a length of 20 μm or more in a cross-section and fine particles smaller than the coarse particles.