The present invention relates to parts of transparent corundum ceramics and the production and use of said parts.

A magnetoelectric effect material includes as a primary component, a polycrystalline oxide ceramic containing at least Sr, Co, and Fe. In the polycrystalline oxide ceramic, the crystal c-axis is oriented in a predetermined direction, and the degree of orientation of the c-axis is 0.2 or more by a Lotgering method. A component substrate is formed of this magnetoelectric effect material.

A production process for a crystal oriented ceramics includes: a first step of preparing composite particles formed of particles having magnetic anisotropy having magnetic susceptibility anisotropy and seed particles having magnetic susceptibility anisotropy less than or equal to 1/10 of the magnetic susceptibility anisotropy of the particles having magnetic anisotropy and are formed of an inorganic compound having an anisotropic shape in which a crystal axis intended to be corresponds to a minor axis or a major axis; a second step of adding raw material powder including the composite particles to a solvent to prepare a slurry a third step of preparing a green compact by disposing the slurry in a static magnetic field of >0.1 tesla and drying the slurry in a state in which crystal axes of the seed particles in a major axis direction are in one direction; and a fourth step of sintering the green compact.

Provided is a ferrite sintered magnet including a ferrite phase having a magnetoplumbite-type crystal structure. x, y, and m satisfy the following Equations (1), (2), and (3) when composition of the ferrite sintered magnet is represented by R.sub.1-xA.sub.xFe.sub.m-yCo.sub.y, where R denotes at least one kind of element selected from rare earth elements including Y and A denotes Ca or Ca and elements including at least one kind selected from Sr or Ba. The content of B in the ferrite sintered magnet is from 0.1% to 0.6% by mass in terms of B.sub.2O.sub.3.
0.2x0.8(1)
0.1y0.65(2)
3m14(3)

A ferrite sintered magnet includes a composition expressed by a formula (1) of Ca.sub.1-w-xLa.sub.wA.sub.xFe.sub.zCo.sub.mMn.sub.aO.sub.19. In the formula (1), w, x, z, m, and a satisfy a formula (2) of 0.21w0.62, a formula (3) of 0.02x0.46, a formula (4) of 7.43z11.03, a formula (5) of 0.18m0.41, and a formula (6) of 0.046a0.188. In the formula (1), A is at least one kind of element selected from a group consisting of Sr and Ba.

The invention proposed a novel hot pressing flowing sintering method to fabricate textured ceramics. The perfectly 2-dimensional textured Si3N4 ceramics (Lotgering orientation factor fL 0.9975) were fabricated by this method. During the initial sintering stage, the specimen flowed along the plane which is perpendicular to the hot pressing direction under pressure, through the controlling of the graphite die movement. The rod-like -Si3N4 nuclei was easily to texture during the flowing process, due to the small size of the -Si3N4 nuclei and the high porosity of the flowing specimen. After aligned, the -Si3N4 grains grew along the materials flowing direction with little constraint. textured Si3N4 ceramics fabricated by this invention also showed high aspect ratio. Compared to the conventional hot-forging technique which contained the sintering and forging processes, hot pressing flowing sintering proposed is simpler and lower cost to fabricate textured Si3N4.

An electromagnetic effect material includes as a primary component, a polycrystalline oxide ceramic containing at least Sr, Co, and Fe. In the polycrystalline oxide ceramic, the crystal c-axis is oriented in a predetermined direction, and the degree of orientation of the c-axis is 0.2 or more by a Lotgering method. A component substrate is formed of this electromagnetic effect material.

A sintered ferrite magnet comprises a main phase of an M type Sr ferrite having a hexagonal crystal structure. An amount of Zn is 0.05 to 1.35 mass % in terms of ZnO and M1/M2 is 0.43 or less when an amount of a rare-earth element (R) is M1 in terms of mol and the amount of Zn is M2 in terms of mol.

A sintered ferrite magnet comprising main phases of ferrite having a hexagonal M-type magnetoplumbite structure, first grain boundary phases existing between two main phases, and second grain boundary phases existing among three or more main phases, the second grain boundary phases being dispersed in its arbitrary cross section, and the second grain boundary phases having an average area of less than 0.2 m.sup.2, are produced by calcining, pulverizing, molding and sintering raw material powders having the general formula of Ca.sub.1-x-yLa.sub.xA.sub.yFe.sub.2n-zCo.sub.z, wherein 1xy, x, y and z and n representing a molar ratio are in desired ranges; 1.8% or less by mass of SiO.sub.2 and 2% or less by mass (as CaO) of CaCO.sub.3 being added to a calcined body after calcining and before molding; and the sintering step being conducted with a temperature-elevating speed of 1-4 C./minute in a range from 1100 C. to a sintering temperature, and a temperature-lowering speed of 6 C./minute or more in a range from the sintering temperature to 1100 C.

A sintered ferrite magnet comprises a main phase of an M type Sr ferrite having a hexagonal crystal structure. An amount of Zn is 0.05 to 1.35 mass % in terms of ZnO, the sintered ferrite magnet does not substantially include a rare-earth element (R), and the following Formula (1) is satisfied, where a total amount of Sr, Ba and Ca is M3 in terms of mol, a total amount of Fe, Co, Mn, Zn, Cr and Al is M4 in terms of mol, and an amount of Si is M5 in terms of mol.
0.5{M3(M4/12)}/M54.8(1).