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.

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.

The present invention provides a ferrite sintered magnet comprising (1) main phase grains containing a ferrite having a hexagonal structure, (2) two-grain boundaries formed between two of the main phase grains, and (3) multi-grain boundaries surrounded by three or more of the main phase grains. The above ferrite sintered magnet comprises Ca, R, Sr, Fe and Co, with R being at least one element selected from the group consisting of rare earth elements and Bi, and comprising at least La. The number Nm of the above main phase grains and the number Ng of the above multi-grain boundaries in the cross section including the direction of the easy magnetization axis of the above ferrite sintered magnet satisfy the formula (1A):
50%≤Nm/(Nm+Ng)≤65%  (1A).

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.

Some variations provide a magnetically anisotropic structure comprising a magnetically anisotropic film on a substrate, wherein the magnetically anisotropic film contains a plurality of discrete magnetic hexaferrite particles, wherein the film is characterized by an average film thickness from 1 micron to 5 millimeters, and wherein the magnetically anisotropic film contains from 2 wt % to 75 wt % organic matter. Some variations provide a magnetically anisotropic structure comprising an out-of-plane magnetically anisotropic film on a substrate, wherein the magnetically anisotropic film contains a plurality of discrete magnetic hexaferrite particles, wherein the film is characterized by an average film thickness from 1 micron to 5 millimeters, and wherein the magnetically anisotropic film contains a concentration of hexaferrite particles of at least 40 vol %. The magnetically anisotropic structures are fabricated at low temperatures so that the magnetically anisotropic film may be monolithically integrated into an integrated-circuit fabrication process.

A ferrite magnet includes: a hexagonal ferrite main phase; and a second phase. The second phase is an oxide phase containing: an element A which is at least one selected from the group consisting of Ca, Sr, Ba, Bi, and rare earth elements; a transition metal element T including at least Fe; and an element G which is at least one selected from the group consisting of Si, Al, B, F, K, Na, Li, P, and S. When the total number of atoms of the element A, the transition metal element T, and the element G in the second phase is set to 100 at %, the element A occupies 30 to 80 at %, the element G occupies 15 to 40 at %, and the transition metal element T occupies less than 4 at %.

The present invention provides: a ferrite particle containing a crystal phase component containing a perovskite crystal represented by the compositional formula RZrO.sub.3 (where R is an alkaline earth metal element); and an electrophotographic developer carrier core material, an electrophotographic developer carrier, and an electrophotographic developer containing the ferrite particles.

The present invention provides: a ferrite particle containing a crystal phase component containing a perovskite crystal represented by the compositional formula RZrO.sub.3 (where R is an alkaline earth metal element); and an electrophotographic developer carrier core material, an electrophotographic developer carrier, and an electrophotographic developer containing the ferrite particles.