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.

Disclosed herein are embodiments of composite hexagonal ferrite materials formed from a combination of Y phase and Z phase hexagonal ferrite materials. Advantageously, embodiments of the material can have a high resonant frequency as well as a high permeability. In some embodiments, the materials can be useful for magnetodielectric antennas.

A ceramic composition contains Fe, Cu, Ni, Zn, Co, and Cr. When Fe, Cu, Ni, and Zn are converted to Fe.sub.2O.sub.3, CuO, NiO, and ZnO, respectively, and a total amount of Fe.sub.2O.sub.3, CuO, NiO, and ZnO is 100 parts by mole, the ceramic composition contains from 48.20 to 49.85 parts by mole Fe in terms of Fe.sub.2O.sub.3, from 2.00 parts to 8.00 parts by mole Cu in terms of CuO, from 11.90 to 18.70 parts by mole Ni in terms of NiO, and from 27.00 to 33.50 parts by mole Zn in terms of ZnO. When Fe, Cu, Ni, and Zn are converted to Fe.sub.2O.sub.3, CuO, NiO, and ZnO, respectively, and a total amount of Fe.sub.2O.sub.3, CuO, NiO, and ZnO is 100 parts by weight, the ceramic composition contains from 5 to 100 ppm Co in terms of CoO and from 10 to 400 ppm in terms of Cr.sub.2O.sub.3.

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.

When the porous ceramic structure contains Co together with Fe or Mn, the Co content is higher than or equal to 0.1 mass % and lower than or equal to 3.0 mass % in terms of Co.sub.3O.sub.4, and when the porous ceramic structure contains Co without containing Fe and Mn, the Co content is higher than or equal to 0.2 mass % and lower than or equal to 6.0 mass % in terms of Co.sub.3O.sub.4. The ratio of the sum of the Fe content in terms of Fe.sub.2O.sub.3, the Mn content in terms of Mn.sub.2O.sub.3, and the Co content in terms of Co.sub.3O.sub.4 to the Ce content in terms of CeO.sub.2 is higher than or equal to 0.8 and lower than or equal to 9.5.

Provided is a red mud-based composite calcium ferrite and a preparation method and use thereof. The preparation method of the red mud-based composite calcium ferrite includes the following steps: mixing red mud and a calcium source, and roasting an obtained mixture in an oxygen-containing atmosphere to obtain the red mud-based composite calcium ferrite; where the calcium source is selected from the group consisting of lime and calcium carbonate. In the present disclosure, the composite calcium ferrite is prepared using a solid waste red mud, with a greatly reduced cost of raw materials; on the other hand, compared with traditional calcium ferrite, the composite calcium ferrite mainly has phase structures of CaFe.sub.2O.sub.4, Ca.sub.2FeAlO.sub.5, and Ca.sub.2Fe.sub.2O.sub.5. Therefore, the composite calcium ferrite has a lower melting point, a higher lime dissolution efficiency, and better fluxing and dephosphorization effects during primary smelting and refining of molten steel, and has broad prospects for use in industry.

The present invention relates to a ferrite particle containing a crystal phase component containing a perovskite crystal represented by a compositional formula: RZrO.sub.3 (provided that R represents an alkaline earth metal element), having a surface roughness Rz of 0.8 .Math.m or more and 3.5 .Math.m or less, and having a standard deviation Rzσ of the surface roughness Rz falling in a range represented by the following formula 0.15 × Rz ≤ Rzσ ≤ 0.60 × Rz. The ferrite particle can be used as an electrophotographic developer carrier core material. In addition, an electrophotographic developer carrier and an electrophotographic developer can be obtained.

Provided is a ferrite sintered magnet including: magnetoplumbite type ferrite crystal grains; and a two-grain boundary interposed between the ferrite crystal grains. The two-grain boundary contains Ca and La, and an atomic ratio Ca/La at the two-grain boundary is 0.3 to 3.0.

Disclosed herein are doped perovskite oxides. The doped perovskite oxides may be used as a cathode material in an electrochemical cell to electrochemically generate ammonia from N.sub.2. The doped perovskite oxides may be combined with nitride compounds, for instance iron nitride, to further increase the efficiency of the ammonia production.

A glass-ceramic-ferrite composition containing a glass, a ferrite, and a ceramic filler, in which the glass contains, by weight, about 0.5% to about 5.0% R.sub.2O (R represents at least one selected from the group consisting of Li, Na, and K), about 5.0% or less Al.sub.2O.sub.3, about 10.0% to about 25.0% B.sub.2O.sub.3, and about 70.0% to 85.0% SiO.sub.2 with respect to the total weight of the glass, the percentage by weight of the ferrite is about 10% to 80% with respect to the total weight of the composition, the ceramic filler contains at least forsterite selected from forsterite and quartz, the percentage by weight of the forsterite is about 1% to about 10% with respect to the total weight of the composition, and the percentage by weight of the quartz is about 40% or less with respect to the total weight of the composition.