Ferrite powder of the present invention is ferrite powder detectable with a metal detector, comprising: soft ferrite particles containing Mn of 3.5 mass % or more and 20.0 mass % or less and Fe of 50.0 mass % or more and 70.0 mass % or less. It is preferable that a volume average particle diameter of the particles constituting the ferrite powder is 0.1 μm or more and 100 μm or less. It is preferable that magnetization by a VSM measurement when magnetic field of 5 K.Math.1000/4πA/m is applied is 85 A.Math.m.sup.2/kg or more and 98 A.Math.m.sup.2/kg or less.

A magnetic sheet according to the present invention contains Mn—Zn ferrite as a main component and is comprised of a sheet-shaped sintered body. Besides, a ratio of Z.sub.MIN to Z.sub.MAX (Z.sub.MIN/Z.sub.MAX×100) is 90% or more, in which a maximum value of a content of Zn in terms of oxide is set to Z.sub.MAX and a minimum value of the content of Zn in terms of oxide is set to Z.sub.MIN in a thickness direction of a cross section of the sintered body.

A method for producing a MnZn ferrite core used at a frequency of 1 MHz or more and an exciting magnetic flux density of 75 mT or less, the MnZn ferrite comprising 53-56% by mol of Fe (calculated as Fe.sub.2O.sub.3), and 3-9% by mol of Zn (calculated as ZnO), the balance being Mn (calculated as MnO), as main components, and 0.05-0.4 parts by mass of Co (calculated as Co.sub.3O.sub.4) as a sub-component, per 100 parts by mass in total of the main components (calculated as the oxides); comprising a step of molding a raw material powder for the MnZn ferrite to obtain a green body; a step of sintering the green body and cooling it to a temperature of lower than 150 C. to obtain a sintered body of MnZn ferrite; and a step of conducting a heat treatment comprising heating the sintered body of MnZn ferrite to a temperature meeting Condition 1 of 200 C. or higher, and Condition 2 of (Tc90) C. to (Tc+100) C., wherein Tc is a Curie temperature ( C.) calculated from the percentages by mol of Fe.sub.2O.sub.3 and ZnO contained in the main components of the MnZn ferrite, keeping the sintered body at the above temperature for a predetermined period of time, and then cooling the sintered body from the keeping temperature at a speed of 50 C./hour or less.

A MnZn-based ferrite that can suppress both reduction of the loss at a high frequency and a change in magnetic properties in a high magnetic field and a method for producing the same are provided. A MnZn-based ferrite including Fe.sub.2O.sub.3, ZnO, and MnO as main components, in which Fe.sub.2O.sub.3 is 53.2 to 56.0 mol % and ZnO is 3.0 to 12.0 mol %, with a balance of MnO, in 100 mol % of the main components, the MnZn-based ferrite includes 0.005 to 0.060% by mass of SiO.sub.2, 0.010 to 0.060% by mass of CaO, 0.10 to 0.40% by mass of CO.sub.2O.sub.3, and 0.05 to 0.30% by mass of TiO.sub.2, as auxiliary components, per 100% by mass of the main components, an average crystal grain diameter is 4 m or less, and a sintering density is 4.8 g/cm.sup.3 or more.

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 m or more and less than 8 m and a density of 4.65 g/cm.sup.3 or more.

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 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.

Superparamagnetic nanocomposites are provided. In an embodiment, a superparamagnetic nanocomposite comprises a superparamagnetic core comprising a first, soft superparamagnetic ferrite and a superparamagnetic shell comprising a second, soft superparamagnetic ferrite, the shell formed over the core, wherein the first and second soft superparamagnetic ferrites are different compounds and have different magnetocrystalline anisotropies.

The disclosed technology generally relates dielectric materials, and more particularly to a combination of co-fireable dielectric materials that can be attached to each other without the use of adhesives. In an aspect, a composite article comprises a magnetic portion comprising a nickel zinc ferrite. The composite article additionally comprises a non-magnetic portion contacting the magnetic portion, the non-magnetic portion comprising a spinel-structured oxide comprising Mg.sub.2-xAl.sub.2xTi.sub.1-xO.sub.4 and having a dielectric constant between about 7 and 14, wherein 0<x1.

Disclosed are a manganese zinc ferrite, a preparation method therefor and the use thereof. The manganese zinc ferrite comprises main components and auxiliary components, wherein the main components comprise iron oxide, zinc oxide and manganese monoxide; and according to the total amount of 100 mol % of the main components, the content of ferric oxide is 52.75-53.15 mol %, the content of zinc oxide is 9.1-10.7 mol %, and the balance being manganese monoxide.