A method for improving the Bs of an MnZn power ferrite material by moving the valley point includes the following steps: 1) mixing Fe.sub.2O.sub.3, MnO and ZnO, and performing primary sanding; 2) adding glue, performing spraying and granulating, and then performing pre-sintering to obtain a pre-sintered material; 3) adding additives to the pre-sintered material, and performing secondary sanding; and 4) adding glue to the secondary sanded material, performing spraying and granulating, pressing into a standard ring, and then performing sintering. The method controls and moves the valley point, reduces loss and improves the Bs of a material by controlling the Fe.sub.2O.sub.3 content and the Co.sub.2O.sub.3 content, and the method is relatively simple and suitable for industrialization.

A multilayer coil component that includes a multilayer body in which a plurality of insulating layers are stacked in a stacking direction and a coil inside the multilayer body, and outer electrodes that are on surfaces of the multilayer body and are electrically connected to the coil. The insulating layers include a spinel-structure ferrite phase and a ZnFe(BO.sub.3)O-type crystalline phase.

A multilayer coil component includes a multilayer body in which a plurality of insulating layers are stacked in a stacking direction and a coil inside, and outer electrodes on surfaces of the multilayer body and electrically connected to the coil. The insulating layers have a magnetic phase having spinel structure containing at least Fe, Ni, Zn, and Cu and a non-magnetic phase containing at least Si. When grain sizes D50 and D90 of crystal grains constituting the magnetic phase are respectively defined as equivalent-area circle diameters of 50% and 90% on a cumulative sum basis in a cumulative distribution of equivalent-area circle diameters of the crystal grains, the grain size D50 is from 50 nm to 750 nm, and the grain size D90 is from 200 nm to 1500 nm.

When manufacturing a magnetic body which is made of a ferrite material containing Fe, Ni, and Zn, and whose Mn content is 0.1288 percent by mass or higher, or a magnetic body which is made of a ferrite material containing Fe, Ni, Zn, and Cu, and whose Mn content is 0.1178 percent by mass or higher, an iron oxide powder whose Mn content is 0.20 percent by mass or higher is used as a raw material powder.

When manufacturing a magnetic body whose primary component is Ni—Zn ferrite, an iron oxide powder whose Mn content is 0.20 to 0.85 percent by mass is used as a raw material powder, or, in addition to using an iron oxide powder whose Mn content is 0.20 percent by mass or higher as a raw material powder, a mol ratio of Ni to Zn (Ni/Zn) in the ferrite material is determined based on the Mn content in the iron oxide powder and the raw material powders are compounded in such a way that the mol ratio is achieved. The magnetic body does not contain any additives as essential components other than the primary components of the Ni—Zn ferrite material. A coil component using the magnetic body has excellent direct-current superimposition property and magnetic permeability.

A composition and a solid material is especially suitable for the manufacture of an antenna adapted to operate in the very high frequency and ultra high frequency or V/UHF band. The composition has the formula Ni.sub.aZn.sub.bCu.sub.cCo.sub.dFe.sub.2-δO.sub.4, in which 2(a+b+c+d)+3(2−δ)=8, 0.05<b<0.5, e.g. 0.1<b<0.5, e.g. 0.1<b<0.4, e.g. 0.15<b<0.35, 0.10<c<0.25, preferably 0.15<c<0.25, alternatively c is 0.20, 0.04<d<0.25, preferably 0.06<d<0.25, and more preferably 0.07<d<0.25, and δ<0.05.

A ceramic composition contains Fe, Cu, Ni, Zn, Co, and Cr. When Fe, Cu, Ni, and Zn are converted to Fe.sub.2O.sub.3, CuO, NiO, and ZnO, respectively, and when a total amount of Fe.sub.2O.sub.3, CuO, NiO, and ZnO is 100 parts by mole, the ceramic composition contains 45.00 to 49.70 parts by mole Fe in terms of Fe.sub.2O.sub.3, 2.00 to 8.00 parts by mole Cu in terms of CuO, 19.40 to 45.40 parts by mole Ni in terms of NiO, and 1.00 to 27.00 parts by mole Zn in terms of ZnO. When Fe, Cu, Ni, and Zn are converted to Fe.sub.2O.sub.3, CuO, NiO, and ZnO, respectively, and when a total amount of Fe.sub.2O.sub.3, CuO, NiO, and ZnO is 100 parts by weight, the ceramic composition contains 5 to 100 ppm Co in terms of CoO and 10 to 400 ppm Cr in terms of Cr.sub.2O.sub.3.

A ceramic composition contains Fe, Cu, Ni, Zn, Co, and Cr. When Fe, Cu, Ni, and Zn are converted to Fe.sub.2O.sub.3, CuO, NiO, and ZnO, respectively, and a total amount of Fe.sub.2O.sub.3, CuO, NiO, and ZnO is 100 parts by mole, the ceramic composition contains from 48.20 to 49.85 parts by mole Fe in terms of Fe.sub.2O.sub.3, from 2.00 parts to 8.00 parts by mole Cu in terms of CuO, from 11.90 to 18.70 parts by mole Ni in terms of NiO, and from 27.00 to 33.50 parts by mole Zn in terms of ZnO. When Fe, Cu, Ni, and Zn are converted to Fe.sub.2O.sub.3, CuO, NiO, and ZnO, respectively, and a total amount of Fe.sub.2O.sub.3, CuO, NiO, and ZnO is 100 parts by weight, the ceramic composition contains from 5 to 100 ppm Co in terms of CoO and from 10 to 400 ppm in terms of Cr.sub.2O.sub.3.

Disclosed herein are embodiments of low temperature co-fireable barium tungstate materials which can be used in combination with high dielectric materials, such as nickel zinc ferrite, to form composite structures, in particular for isolators and circulators for radiofrequency components. Embodiments of the material can include flux, such as bismuth vanadate, to reduce co-firing temperatures.

A ferrite ceramic composition includes, as main components, from 27.0 mol % to 41.0 mol % of Fe in terms of Fe.sub.2O.sub.3, from 16.0 mol % to 24.0 mol % of Ni in terms of NiO, from 23.0 mol % to 37.0 mol % of Zn in terms of ZnO, from 5.0 mol % to 9.0 mol % of Cu in terms of CuO, and from 4.0 mol % to 14.0 mol % of Si in terms of SiO.sub.2, and as sub-components, relative to 100 parts by mass of the main components, from 0.3 parts by mass to 1.2 parts by mass of Bi in terms of Bi.sub.2O.sub.3, from 0.3 parts by mass to 1.2 parts by mass of Co in terms of Co.sub.3O.sub.4, from 0.01 parts by mass to 0.25 parts by mass of Mn in terms of Mn.sub.2O.sub.3, and from 0.003 parts by mass to 0.030 parts by mass of Cr in terms of Cr.sub.2O.sub.3.