A manganese-zinc ferrite with a high magnetic permeability at negative temperature and low loss at high temperature consists of Fe.sub.2O.sub.3, MnO and ZnO, and additives consisting of CaCO.sub.3, ZrO.sub.2, Co.sub.2O.sub.3 and SnO.sub.2 are also added. A method for preparing the manganese-zinc ferrite is further provided. According to the method, by reasonably adjusting a ratio of Mn to Zn to Fe and appropriately increasing the content of Co in the additives, a manganese-zinc ferrite material with both a high magnetic permeability and low loss at about −20° C. and low loss at 120-140° C. is obtained. The manganese-zinc ferrite material has two loss valleys at about −20° C. and about 100° C. in a temperature range of −30° C. to 140° C., which expands the application range of the manganese-zinc ferrite material.

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.

Embodiments relate to an improved hydroflux assisted densification process that introduces a transport phase (formed by the introduction of water during the process to suppress melting temperatures) for sintering, the transport phase being a non-aqueous solution. The process can facilitate sintering at low temperature ranges (at or below 300° C.) to yield densification>90% without the need for additional post-processing steps that otherwise would be needed if conventional processes were used. Control of the pressures and water content used during the process can enhance densification mechanisms related to dissolution-reprecipitation, allowing for a greater range of compositional spectra of materials that can be densified, a reduction of the amount of transport phase needed, a reduction of impurities and an improvement of properties in the densified material. Certain hydrated acetate powders can be used to generate a hydroxide mixture flux that is better for the low-temperature densification process.

A method for manufacturing a sintered body, the method including heating a mixture that contains a plurality of particles of a metal oxide having a spinel-type structure, and a metal acetylacetonate under pressure at a temperature of from a melting point or higher of the metal acetylacetonate to 600° C. or lower, to form a sintered body that contains the metal oxide having the spinel-type structure.

A method for producing MnZn-ferrite comprising Fe, Mn and Zn as main components, and at least Co, Si and Ca as sub-components, the main components in the MnZn-ferrite comprising 53-56% by mol (as Fe.sub.2O.sub.3) of Fe, and 3-9% by mol (as ZnO) of Zn, the balance being Mn as MnO, comprising the step of sintering a green body to obtain MnZn-ferrite; the sintering comprising a temperature-elevating step, a high-temperature-keeping step, and a cooling step; the high-temperature-keeping step being conducted at a keeping temperature of higher than 1050° C. and lower than 1150° C. in an atmosphere having an oxygen concentration of 0.4-2% by volume; the oxygen concentration being in a range of 0.001-0.2% by volume during cooling from 900° C. to 400° C. in the cooling step; and the cooling speed between (Tc+70)° C. and 100° C. being 50° C./hour or more, wherein Tc represents a Curie temperature (° C.) calculated from % by mass of Fe.sub.2O.sub.3 and ZnO.

Provided are: a MnZn-based ferrite which allows to have a low magnetic core loss and to suppress a time-dependent change of magnetic property under a high-temperature environment by a control of ambient oxygen concentration and an increase of the magnetic core loss, and a method for manufacturing the same. The MnZn-based ferrite is characterized in that Fe ranges from 53.25 mol % or more to 54.00 mol % or less on the basis of Fe.sub.2O.sub.3, Zn ranges from 2.50 mol % or more to 8.50 mol % or less on the basis of ZnO and Mn is the remainder on the basis of MnO, Si ranges from more than 0.001 mass % to less than 0.02 mass % on the basis of SiO.sub.2, Ca ranges from more than 0.04 mass % to less than 0.4 mass % on the basis of CaCO.sub.3, Co is less than 0.5 mass % on the basis of Co.sub.3O.sub.4, Bi is less than 0.05 mass % on the basis of Bi.sub.2O.sub.3, Ta is less than 0.05 mass % on the basis of Ta.sub.2O.sub.5, Nb is less than 0.05 mass % on the basis of Nb.sub.2O.sub.5, Ti is less than 0.3 mass % on the basis of TiO.sub.2, and Sn is less than 0.3 mass % on the basis of SnO.sub.2, and note that the converted total amount of Ta.sub.2O.sub.5 and Nb.sub.2O.sub.5 is less than 0.05 mass % and the converted total amount of TiO.sub.2 and SnO.sub.2 is less than 0.3 mass %.

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 sintered MnZn ferrite body containing main components comprising 53.30-53.80% by mol of Fe calculated as Fe.sub.2O.sub.3, 6.90-9.50% by mol Zn calculated as ZnO, and the balance of Mn calculated as MnO, and sub-components comprising 0.003-0.020 parts by mass of Si calculated as SiO.sub.2, more than 0 parts and 0.35 parts or less by mass of Ca calculated as CaCO.sub.3, 0.30-0.50 parts by mass of Co calculated as Co.sub.3O.sub.4, 0.03-0.10 parts by mass of Zr calculated as ZrO.sub.2, and 0-0.05 parts by mass of Ta calculated as Ta.sub.2O.sub.5, pre 100 parts by mass in total of the main components (calculated as the oxides), and having an average crystal grain size of 3 μm or more and less than 8 μm and a density of 4.65 g/cm.sup.3 or more.

A composite magnetic material has a plurality of grains having a magnetic ferrite phase, grain boundaries surrounding the grains, and a plurality of nanoparticles disposed at the grain boundaries. The nanoparticles of the composite material are both magnetic and electrically insulating, having a magnetic flux density of greater than about 100 mT and an electrical resistivity of at least about 10.sup.8 Ohm-cm. Also provided is a method of making the composite material. The material is useful for making inductor cores of electronic devices.

A multiphase ferrite composition includes a primary phase consisting of a MnZn ferrite matrix; and 0.01 to 10 weight percent microscaled inclusion particles comprising an orthoferrite RFeO3 wherein R is a rare earth ion, yttrium iron garnet (YIG), or a combination thereof, wherein the microscaled inclusion particles have an average particle size (D50) of 0.1 micron to 5 microns, and wherein the D50 of the microscaled inclusion particles is smaller than the average particle size (D50) of the MnZn ferrite particles; and optionally 0.01 to 5 weight percent additive; wherein weight percent is based on the total weight of the multiphase ferrite composition. A method of manufacturing the multiphase ferrite composition is also disclosed.