A ceramic and a preparation method therefor are provided. The ceramic includes a zirconia matrix, and an additive dispersed inside and on an outer surface of the zirconia matrix. The additive is an oxide including elements A and B, where A is selected from at least one of Ca, Sr, Ba, Y, and La, and B is selected from at least one of Cr, Mn, Fe, Co, and Ni.

There is provided a ferrite powder for bonded magnets capable of producing ferrite bonded magnets with high BH.sub.max, excellent in MFR when converted to a compound, with high p-iHc, wherein an average particle size of particles obtained by a dry laser diffraction measurement is 5 μm or less, a specific surface area is 1.90 m.sup.2/g or more and less than 3.00 m.sup.2/g, a compression density is 3.40 g/cm.sup.3 or more and less than 3.73 g/cm.sup.3, and a compressed molding has a coercive force of 2800 Oe or more and less than 3250 Oe.

A piezoelectric material contains: a first component which is a rhombohedral crystal in a single composition, has a Curie temperature Tc1, and is a lead-free-system composite oxide having a perovskite-type structure; a second component which is a crystal other than a rhombohedral crystal in a single composition, has a Curie temperature Tc2 higher than Tc1, and is a lead-free-system composite oxide having a perovskite-type structure; and a third component which is a rhombohedral crystal in a single composition, has a Curie temperature Tc3 equal to or higher than Tc2, and is a lead-free-system composite oxide that has a perovskite-type structure and is different from the first component. When a molar ratio of the third component to the sum of the first component and the third component is α and α×Tc3+(1−α)×Tc1 is Tc4, |Tc4−Tc2| is 50° C. or lower.

Provided is a zirconia sintered body that suppresses discoloration due to porcelain. The zirconia sintered body comprises at least one of a coloring agent A: erbium oxide and a coloring agent B: nickel oxide, and a composite oxide of zirconium and vanadium.

A sintered Ni ferrite body having a composition comprising, calculated as oxide, 47.0-48.3% by mol of Fe.sub.2O.sub.3, 14.5% or more and less than 25% by mol of ZnO, 8.2-10.0% by mol of CuO, and more than 0.6% and 2.5% or less by mol of CoO, the balance being NiO and inevitable impurities, and having an average crystal grain size of more than 2.5 μm and less than 5.5 μm.

A polycrystalline fused product based on brownmillerite, includes, for more than 95% of its weight, of the elements Ca, Sr, Fe, O, M and M′, the contents of the elements being defined by the formula X.sub.yM.sub.zFe.sub.tM′.sub.uO.sub.2.5, wherein the atomic indices are such that 0.76≤y≤1.10, z≤0.21, 0.48≤t≤1.15 and u≤0.52, 0.95≤y+z≤1.10, and 0.95≤t+u≤1.10, X being Ca or Sr or a mixture of Ca and Sr, M being an element chosen from the group formed by La, Ba and mixtures thereof, M′ being an element chosen from the group formed by Ti, Cu, Gd, Mn, Al, Sc, Ga, Mg, Ni, Zn, Pr, In, Co, and mixtures thereof, the sum of the atomic indices of Ti and Cu being less than or equal to 0.1.

A method for preparing an infrared radiation ceramic material includes mixing and ball milling raw materials of Fe.sub.2O.sub.3, MnO.sub.2 and CuO in a mass ratio to obtain a mixed powder; pressing the mixed powder; adjusting laser spot, laser power and laser sintering time of a laser; irradiating or sintering by a first laser the pressed mixed powder in a crucible for a high-temperature solid-phase reaction to obtain an AB.sub.2O.sub.4 type ferrite powder; obtaining a first mixture by mixing the AB.sub.2O.sub.4 type ferrite powder and a cordierite powder in a mass ratio; adding a sintering aid and a nucleating agent for ball milling; obtaining a second mixture by mixing the first mixture and a binder for aging; pressing the second mixture; and irradiating or sintering the pressed second mixture by a second laser to obtain the infrared radiation ceramic material.

A multilayer coil component including a magnetic part formed of a ferrite material, a non-magnetic part formed of a non-magnetic ferrite material, and a coiled conductive part embedded in the magnetic part and the non-magnetic part. The non-magnetic part has an Fe content of 36.0 to 48.5 mol % in terms of Fe.sub.2O.sub.3, a Zn content of 46.0 to 57.5 mol % in terms of ZnO, a V content of 0.5 to 5.0 mol % in terms of V.sub.2O.sub.5, a Mn content of 0 to 7.5 mol % in terms of Mn.sub.2O.sub.3, and a Cu content of 0 to 5.0 mol % in terms of CuO with respect to the sum of the Fe content in terms of Fe.sub.2O.sub.3, the Zn content in terms of ZnO, the V content in terms of V.sub.2O.sub.5, and if present, the Cu content in terms of CuO, and the Mn content in terms of Mn.sub.2O.sub.3.

A ferrite composition comprises a main component and a subcomponent. The main component includes 32.0 to 46.4 mol % of iron oxide in terms of Fe.sub.2O.sub.3, 4.4 to 14.0 mol % of copper oxide in terms of CuO, and 8.4 to 56.9 mol % of zinc oxide in terms of ZnO. The subcomponent includes 0.53 to 11.00 parts by weight of a silicon compound in terms of SiO.sub.2, 0.1 to 12.8 parts by weight of a tin compound in terms of SnO.sub.2, and 0.5 to 7.0 parts by weight of a bismuth compound in terms of Bi.sub.2O.sub.3, with respect to 100 parts by weight of the main component.

The invention relates to a process for metallizing ferrite ceramics, which comprises the following steps: arrangement of a contact element composed of copper or a copper alloy on a surface of the ferrite ceramic, melting of the contact element at least in the region in which the contact element contacts the surface of the ferrite ceramic, and cooling of the contact element and the ferrite ceramic to below the melting point of copper or the copper alloy.