Disclosed are a mixed oxide composition based on zirconium and cerium exhibiting a high reducibility, the process for preparing it and its use in the field of catalysis.

A hexagonal strontium ferrite powder, in which an average particle size is 10.0 to 25.0 nm, a content of one or more kinds of atom selected from the group consisting of a gallium atom, a scandium atom, an indium atom, and an antimony atom is 1.0 to 15.0 atom % with respect to 100.0 atom % of an iron atom, and a coercivity Hc is greater than 2,000 Oe and smaller than 4,000 Oe. A magnetic recording medium including: a non-magnetic support; and a magnetic layer including a ferromagnetic powder and a binding agent on the non-magnetic support, in which the ferromagnetic powder is the hexagonal strontium ferrite powder. A magnetic recording and reproducing apparatus including this magnetic recording medium.

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.

A sintered ferrite magnet having a composition of metal elements of Ca, R, A, Fe and Co, which is represented by the general formula of Ca.sub.1−x−yR.sub.xA.sub.yFe.sub.2n−zCo.sub.z, wherein R is at least one of rare earth elements indispensably including La; A is Sr and/or Ba; x, y, z and n represent the atomic ratios of Ca, R, A, Fe and Co; 2n represents a molar ratio expressed by 2n=(Fe+Co)/(Ca+R+A); and x, y, z and n meet the conditions of 0.15≤x≤0.35, 0.05≤y≤0.40, (1−x−y)>y, 0<z≤0.18, and 7.5≤(2n−z)<11.0.

Disclosed are embodiments of synthetic garnet materials for use in radiofrequency applications. In some embodiments, increased amounts of gadolinium can be added into specific sites in the crystal structure of the synthetic garnet by incorporating indium, a trivalent element. By including both indium and increased amounts of gadolinium, the dielectric constant can be improved. Thus, embodiments of the disclosed material can be advantageous in both above and below resonance applications, such as for isolators and circulators.

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.

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.

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.

The present invention relates to a method of preparation of a garnet-type inorganic material. It also relates to the garnet-type inorganic material itself. The process comprises the following steps: (1) bringing an aqueous solution S comprising (i) a salt of zirconium, (ii) a salt of lanthanum and (iii) a salt of the element A or a precursor of an oxide of element A into contact with an aqueous solution of a basic compound, as a result of which a precipitate suspended in the reaction medium is obtained; (2) stirring the reaction medium obtained at the end of step (1) for at least 30 min; (3) bringing the precipitate obtained at the end of step (2) into contact with an additive selected in the group consisting of: anionic surfactants; nonionic surfactants; polyethylene glycols; carboxylic acids and their salts; and surfactants of the carboxymethylated fatty alcohol ethoxylate type; (4) calcining in air the precipitate recovered at the end of the previous step at a temperature which is at least 400° C.; (5) bringing into contact the product obtained at the end of step (4) with a salt of lithium; (6) calcining in air the product obtained at the end of step (5) at a temperature between 700° C. and 1100° C.; 20 the inorganic compound M comprising or consisting essentially of a garnet oxide or garnet-type oxide containing, as constituent elements, the elements Li, La, Zr and at least one element A selected in the group consisting of Al, Ga, Nb, Fe, W, Ta, or a mixture thereof.

The invention relates to a method for preparing a composite metal oxide hollow fibre. A certain stoichiometry of composite metal oxide raw material and a polymer binding agent are added to an organic solvent, and mixed mechanically to obtain an evenly dispersed spinning solution having a suitable viscosity. After defoaming treatment, the spinning solution is extruded through a spinneret and, after undergoing a certain dry spinning process, enters an external coagulation bath; during this period, a phase inversion process occurs and composite metal oxide hollow fibre blanks are formed. The blanks are immersed in the external coagulation bath and the organic solvent is displaced; after natural drying, the blanks undergo a heat treatment process; during this period, polymer burn off, in situ reaction, and in situ sintering processes occur to obtain the composite metal oxide hollow fibre.