Embodiments disclosed herein relate to using cobalt (Co) to fine tune the magnetic properties, such as permeability and magnetic loss, of nickel-zinc ferrites to improve the material performance in electronic applications. The method comprises replacing nickel (Ni) with sufficient Co.sup.+2 such that the relaxation peak associated with the Co.sup.+2 substitution and the relaxation peak associated with the nickel to zinc (Ni/Zn) ratio are into near coincidence. When the relaxation peaks overlap, the material permeability can be substantially maximized and magnetic loss substantially minimized. The resulting materials are useful and provide superior performance particularly for devices operating at the 13.56 MHz ISM band.

A MnZn-based ferrite that can reduce the loss even when a high-frequency voltage fluctuation occurs is provided. The above MnZn-based ferrite is a MnZn-based ferrite including Fe2O3, ZnO, and MnO as main components, in which Fe2O3 is 53.2 to 56.3 mol % and ZnO is 1.0 to 9.0 mol %, with a balance of MnO, in 100 mol % of the main components, and the MnZn-based ferrite includes 0.9 to 2.0% by mass of Co.sub.2O.sub.3, 0.005 to 0.06% by mass of SiO.sub.2, and 0.01 to 0.06% by mass of CaO, as auxiliary components, per 100% by mass of the main components.

The disclosed technology relates to a ceramic composition and an article formed therefrom. A ceramic article for radio frequency applications is formed of a ceramic material having a chemical formula represented by: Bi.sub.1.0+aY.sub.2.0−a−x−2yCa.sub.x+2yFe.sub.5−x−yM.sup.IV.sub.xV.sub.yO.sub.12 or Bi.sub.1.0+aY.sub.2.0−a−2yCa.sub.2yFe.sub.5−y−zV.sub.yIn.sub.zO.sub.12. The ceramic material has a composition such that a normalized change in saturation magnetization (Δ4πMs), defined as Δ4πMs=[(4πMs at 20° C.)−(4πMs at 120° C.)]/(4πMs at 20° C.), is less than about 0.35.

Provided is a ferrite sintered magnet including a main phase formed of ferrite having a hexagonal magnetoplumbite type crystalline structure, in which the main phase contains Fe and Co, and the ferrite sintered magnet contains CaB.sub.2O.sub.4. CaB.sub.2O.sub.4 is contained in a heterophase that is a crystalline phase different from the main phase, and an area ratio of CaB.sub.2O.sub.4 to the entire cross-sectional surface of a sintered magnet, is less than or equal to 2%.

A magnetic material which is likely to be cracked or chipped. The magnetic material is a magnetic material including ferrite particles and segregated particles containing Bi and Si, and characteristically, the magnetic material contains, as a main constituent, 46.0 mol % to 50.0 mol % Fe.sub.2O.sub.3, 0.4 mol % to 8.0 mol % CuO, 23.0 mol % to 32.0 mol % ZnO, and 18.0 mol % to 22.0 mol % NiO, and the ratio of the average particle size of the segregated particles to the average particle size of the ferrite particles is 0.04 or more and 0.19 or less (i.e., 0.04 to 0.19).

This ferrite sintered magnet comprises metallic elements at an atomic ratio represented by formula (1):
Ca.sub.1-w-xR.sub.wSr.sub.xFe.sub.zCo.sub.m  (1) in formula (1), R is at least one element selected from the group consisting of rare-earth elements and Bi, and R comprises at least La, in formula (1), w, x, z and m satisfy formulae (2) to (5):
0.360≤w≤0.420  (2)
0.110≤x≤0.173  (3)
8.51≤z≤9.71  (4)
0.208≤m≤0.269  (5), and in a section parallel to an axis of easy magnetization, when the number of total ferrite grains is N and the number of ferrite grains having a stacking fault is n, 0≤n/N≤0.20 is satisfied.

This ferrite magnet has a ferrite phase having a magnetoplumbite structure, and an orthoferrite phase, and is characterized in that the composition ratios of the total of each metal element A, R, Fe and Me is represented by expression (1) A.sub.1-xR.sub.x(Fe.sub.12-yMe.sub.y).sub.z, (in expression (1), A is at least one element selected from Sr, Ba, Ca and Pb; R is at least one element selected from the rare-earth elements (including Y) and Bi, and includes at least La, and Me is Co, or Co and Zn) and in that the content (m) of the orthoferrite phase is 0<m<28.0 in mol %. The invention makes it possible to achieve a ferrite magnet with increased Br.

The electrochemical cell has an anode, a cathode, and a solid electrolyte layer. The cathode contains a perovskite oxide expressed by the general formula ABO.sub.3 and includes at least one of Sr and La at the A site as a main component. The solid electrolyte layer is disposed between the anode and the cathode. The cathode includes a solid electrolyte layer-side region within 3 μm from a surface of the solid electrolyte layer side. The solid electrolyte layer-side region includes a main phase which is configured by the perovskite oxide and a second phase which is configured by Co.sub.3O.sub.4 and (Co, Fe).sub.3O.sub.4. An occupied surface area ratio of the second phase in a cross section of the solid electrolyte layer-side region is less than or equal to 10.5%.

A coil device comprising a coil, and a ferrite core arranged in a hollow portion of the coil, and a resin covering them; the ferrite core being a Ni ferrite core having initial permeability μi of 450 or more at a frequency of 100 kHz and a temperature of 20° C., and an average crystal grain size of 5-9 μm, both of temperature-dependent inductance change ratios TLa and TLb and stress-dependent inductance change ratios PLa and PLb being −0.6% to +0.6%, and both of the sum of TLa and PLa and the sum of TLb and PLb being more than −1.0% and less than +1.0%; and an antenna comprising it.

A ferrite composition includes main-phase particles, first sub-phase particles, second sub-phase particles, and a grain boundary. At least 10% or more of the main-phase particles contain a portion whose Zn concentrations monotonously decrease from a particle surface toward a particle central part along a length of 50 nm or more. The first sub-phase particles contain Zn.sub.2SiO.sub.4. The second sub-phase particles contain SiO.sub.2. A total area ratio of the first sub-phase particles and the second sub-phase particles is 30.5% or more.