Provided is a material that can be used as a potassium secondary battery positive electrode active material (particularly a potassium ion secondary battery positive electrode active material), other than Prussian blue, by using a potassium compound and a potassium ion secondary battery positive electrode active material comprising the potassium compound, the potassium compound being represented by general formula (1):
K.sub.nA.sub.kBO.sub.m,
wherein A is a positive divalent element in groups 7 to 11 of the periodic table; B is positive tetravalent silicon, germanium, titanium or manganese, excluding a case in which A is manganese and B is titanium, and a case in which A is cobalt and B is silicon; n is 1.5 to 2.5; and m is 3.5 to 4.5.

Thermochemical storage materials having the general formula A.sub.xA.sub.1-xB.sub.yB.sub.1-yO.sub.3-, where A=La, Sr, K, Ca, Ba, Y and B=Mn, Fe, Co, Ti, Ni, Cu, Zr, Al, Y, Cr, V, Nb, Mo, are disclosed. These materials have improved thermal storage energy density and reaction kinetics compared to previous materials. Concentrating solar power thermochemical systems and methods capable of storing heat energy by using these thermochemical storage materials are also disclosed.

A ferrite sintered magnet comprising an M type Sr ferrite having a hexagonal structure as a main phase, wherein the ferrite sintered magnet does not substantially comprise a rare earth element and Co, a content of B is 0.005 to 0.9% by mass in terms of B.sub.2O.sub.3, and a content of Zn is 0.01 to 1.2% by mass in terms of ZnO.

An object of the present invention is to provide a ferrite carrier core material for an electrophotographic developer having desired resistance properties and charging properties with small environmental variation of resistivity and charge amount while maintaining the advantages of ferrite carriers, a ferrite carrier for an electrophotographic developer, an electrophotographic developer using the ferrite carrier, and a method for manufacturing the ferrite carrier core material for an electrophotographic developer. In order to solve the problem, a ferrite carrier core material comprising ferrite particles containing 15 mass % or more and 25 mass % or less of Mn, 0.5 mass % or more and 5.0 mass % or less of Mg, 0.05 mass % or more and 4.0 mass % of Sr, and 45 mass % or more and 55 mass % or less of Fe, with Si localized in the surface thereof is used.

A method for the rapid and controlled synthesis of mixed metal oxide nanoparticles using relatively low temperature plasma oxidation of liquid droplets of predetermined mixed metal precursors is disclosed. The resulting nanoparticles reflect the metal precursor stoichiometries and the mixed metal oxide's metastable phase can be controlled. The synthesis of mixed transition metal oxide comprising binary metal oxides, ternary mixed metal oxides, quaternary mixed metal oxides and pentanary mixed metal oxides are demonstrated herein.

Provided is a novel positive electrode active material capable of suppressing resistance and improving rate characteristics and cycle characteristics while enhancing lithium ionic conductivity, wherein the surface of particles composed of a spinel-type composite oxide containing Li, Mn, O, and two or more other elements is coated with a lithium ion conductive oxide such as LiNbO.sub.3. Proposed is a positive electrode active material for an all-solid-type lithium secondary battery, wherein the surface of present core particles composed of a spinel-type composite oxide containing Li, Mn, O, and two or more other elements is coated with an amorphous compound containing Li, A (A represents one or more elements selected from the group consisting of Ti, Zr, Ta, Nb, and Al), and O; and the molar ratio (Li/A) of Li relative to the A element in the surface, as obtained by XPS, is 1.0 to 3.5.

Embodiments of a method for synthesizing water-soluble metal oxide nanoparticles are disclosed. In one embodiment, the method includes heating a first reaction mixture at a predetermined temperature for a predetermined time duration with continuous stirring to obtain a second reaction mixture that comprises water-soluble metal oxide nanoparticles of a first size. The first reaction mixture includes a reactant and a polyol. The method further includes adding a first predetermined amount of the reactant to the second reaction mixture to obtain a third reaction mixture. The method further includes heating the third reaction mixture at the predetermined temperature for the predetermined time duration with continuous stirring to obtain a fourth reaction mixture comprising water-soluble metal oxide nanoparticles of a second size. The reactant is Fe(acac).sub.3 and the polyol is diethylene glycol (DEG) for synthesizing water-soluble iron oxide nanoparticles.

MnZn ferrite particles according to the present invention contain 44-60% by mass of Fe, 10-16% by mass of Mn and 1-11% by mass of Zn. The ferrite particles are single crystal bodies having an average particle diameter of 1-2,000 nm, and have polyhedral particle shapes, while having an average sphericity of 0.85 or more but less than 0.95.

Disclosed herein are magnetic nanoparticles, compositions and kits comprising the magnetic nanoparticles, methods of making the magnetic nanoparticles, and methods of using the magnetic nanoparticles to enrich biological targets.

Magnetodielectric (MD) metamaterials have a magnetodielectric (MD) substrate of a ferrite composition or composite having a characteristic impedance matching an impedance of free space and at least one frequency selective surface (FSS). The FSS has a plurality of frequency selective surface elements disposed in a pattern and supported on the MD substrate. The FSS has a conducting composition and is configured to permit one or more of transmission, reflection, or absorption at a selected resonant frequency or selected frequency band. Articles incorporating magnetodielectric metamaterials are provided.