Magnetic hexagonal ferrites, in which ferrites the iron atom may be optionally substituted (substituted or unsubstituted barium hexaferrites, etc.), are prepared in high yields, and under non-corrosive conditions by a hydrothermal synthesis reaction between at least one alkali metal ferrite and a compound which releases an alkaline-earth metal ion in water (baryta, etc.) and optionally one or more alkali metal salt(s) of metal oxides. Magnetic hexagonal ferrites can be used as materials for perm...

The method for slip casting soft ferromagnetic ferrites includes forming a powder of soft ferromagnetic ferrite material, the powder having the formula MeO:Fe.sub.2 O.sub.3 with a molecular ratio of about 1:1. The powder is sized so that it consists of particles having a maximum diameter of about 20 .mu., at least about 5% and no more than about 70 percent by weight of the particles having a diameter smaller than about 2 .mu.. The ferrite powder is suspended in an aqueous solution, the solution ...

A discrete electromagnetic device in which the transformer/inductor function and a capacitive function are integrated is achieved by utilizing both the magnetic permeability and the dielectric constant of one or more soft ferrite layers. The device is comprised of a plurality of soft ferrite planar layers spaced apart in a stacked array. Between each soft ferrite layer is a metallic layer which forms one of the plates of the capacitor. A first and second set of apertures are defined through each...

An oxygen sensor made of alkaline-earth-doped perovskitic lanthanum ferrites with the general formula: where Me is one of the alkaline earth metals, Mg, Ca, Sr, and Ba and x is the degree of doping, and the oxygen deficit of anion .delta.=0 to 0.25. The degree of doping of the lanthanum ferrites is x=0.1 to 0.3 and resistance is measured in the lanthanum ferrites as a function of oxygen partial pressure.

Fire retardant compositions comprise at least one ammonium polyphosphate, at least one suspending agent, and at least one metal ferrite. In specific embodiments, the compositions of the invention comprise zinc ferrite or magnesium ferrite.

A process for the preparation of finely divided acicular hexagonal ferrites which have a high coercive force and are of the general formula MFe.sub.12 O.sub.19, where M is barium or strontium, and their use for the production of magnetic recording media and plastoferrites.

An adsorbent, which has been prepared by mixing (a) one part by weight of (i) at least one member selected from the group consisting of hydrated ferrites of titanium, zirconium and tin or (ii) a mixture of the said hydrated ferrites(s) and at least one member selected from the group consisting of hydrated oxides of titanium, zirconium, tin and iron with (b) about 1/10 to 3 parts by weight of a thermosetting resin showing resistance to acids and alkalis such as an unsaturated polyester or polyure...

By configuring a high impedance frequency selective surface (HZ-FSS) structure for the appropriate values of surface impedance (surface resistance and surface reactance), a high frequency artificial ferrite metamaterial can be synthesized with almost any desired value of real and imaginary permeability. Materials with these properties have not previously been physically realizable at frequencies above 1 GHz.

The invention describes a method of preparing magnetic ferrites from layered precursors in which Fe.sup.2+ is first introduced into the layers of layered double hydroxides (LDHs) in order to prepare Me-Fe.sup.2+--Fe.sup.3+ LDHs, and then by utilizing the easily oxidized nature of Fe.sup.2+, binary or multi-component ferrite materials containing Fe.sup.3+ in a single crystalline phase can be prepared. Values of the saturation magnetization of ferrites prepared by the method are significantly incr...

A hydrometallurgical process for the treatment of a raw material which contains iron and other metals, with a sulfuric acid solution, in order to dissolve the metals and to precipitate and separate the iron, the separated metal sulfate solution being exposed to evaporation in order to crystallize and separate the metal sulfates from the mother liquor, which is recycled to the treatment stage performed with sulfuric acid solution, and the separated metal sulfate being recovered.