Disclosed herein are embodiments of low temperature co-fireable scheelite 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. In some embodiments, the scheelite material can include aluminum oxide for temperature expansion regulation.

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.

A ferrite sintered magnet comprises a plurality of main phase grains containing a ferrite having a hexagonal structure, wherein at least some of the main phase grains are core-shell structure grains each having a core and a shell covering the core; and wherein the minimum value of the content of La in the core is [La]c atom %; the minimum value of the content of Co in the core is [Co]c atom %; the maximum value of the content of La in the shell is [La]s atom %; the maximum value of the content of Co in the shell is [Co]s atom %; [La]c+[Co]c is 3.08 atom % or more and 4.44 atom % or less; and [La]s+[Co]s is 7.60 atom % or more and 9.89 atom % or less.

Disclosed herein are ceramic materials, such as bismuth substituted garnets, which can have high curie temperatures and high dielectric constants. In certain implementations, indium can be incorporated into the ceramic to improve certain properties and to avoid calcium compensation. The ceramic materials disclosed herein can be particular advantageous for below resonance applications.

Embodiments of synthetic garnet materials having advantageous properties, especially for below resonance frequency applications, are disclosed herein. In particular, embodiments of the synthetic garnet materials can have high Curie temperatures and dielectric constants while maintaining low magnetization. These materials can be incorporated into isolators and circulators, such as for use in telecommunication base stations.

It is described a process for producing transparent ceramic bodies with at least two zones having different garnet composition, in particular in which one of said zones has composition Y.sub.3AI.sub.5O.sub.12. The invention is especially useful for the production of transparent ceramic bodies having preset complex shapes and/or a controlled complex distribution of doping ions.

Disclosed are embodiments of synthetic garnet materials for use in radiofrequency applications. In some embodiments, increased amounts of bismuth can be added into specific sites in the crystal structure of the synthetic garnet in order to boost certain properties, such as the dielectric constant and magnetization. Accordingly, embodiments of the disclosed materials can be used in high frequency applications, such as in base station antennas.

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.

Disclosed herein are embodiments of low temperature co-fireable scheelite 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. In some embodiments, the scheelite material can include aluminum oxide for temperature expansion regulation.

Disclosed herein are embodiments of low temperature co-fireable dielectric materials which can be used in conjunction with high dielectric materials to form composite structures, in particular for isolators and circulators for radiofrequency components. Embodiments of the low temperature co-fireable dielectric materials can be scheelite or garnet structures, for example barium tungstate. Adhesives and/or glue is not necessary for the formation of the isolators and circulators.