Disclosed in the present disclosure are a positive electrode material precursor and a positive electrode material and preparation methods therefor, and a sodium-ion battery. The positive electrode material precursor comprises an inner core and a shell wrapping the periphery of the inner core, wherein the inner core is Ni.sub.xFe.sub.yMn.sub.1-x-y(OH).sub.2, where 0.2x0.7, and 0.2y0.5; the shell is M.sub.aMn.sub.1-a(OH).sub.2, where M is nickel or iron, and 0.05a0.7; and both the inner core and the shell are formed by stacking flaky primary particles. In the positive electrode material precursor provided in the present application, by controlling the components of the inner core and the shell and using a loose structure thereof formed by stacking flaky primary particles in combination, a heterostructure positive electrode material with an 03-phase inner core and a P2-phase shell can be obtained; and due to the synergistic effect of the two-phase structure, the heterostructure positive electrode material has both high capacity and high cycle stability, such that the electrochemical performance of a sodium-ion battery can be further improved. In addition, the preparation method for a positive electrode material provided in the present application is simple, has a relatively low cost, and is suitable for industrial large-scale production.

The present disclosure relates to magnetic nanoparticles having a core-multishell structure comprising at least two shells, and methods for their preparation.

A magnetic powder to be included in a cosmetic agent being removable by a magnetic attraction force from the cosmetic agent applied to the skin. The magnetic powder comprises a ferromagnetic ferrite, a mean volume particle diameter of 50 to 75 m when determined from a particle size distribution obtained by a laser diffraction scattering method, a content of particles with a particle diameter of less than 37 m of 15% by mass or less, and a content of particles with a particle diameter of 105 m or more of 5% by mass or less. The magnetic powder preferably has a saturation magnetization of 80 Am.sup.2/kg or more.

A ferrite sintered magnet includes a composition expressed by a formula (1) of Ca.sub.1-w-xLa.sub.wA.sub.xFe.sub.zCo.sub.mMn.sub.aO.sub.19. In the formula (1), w, x, z, m, and a satisfy a formula (2) of 0.21w0.62, a formula (3) of 0.02x0.46, a formula (4) of 7.43z11.03, a formula (5) of 0.18m0.41, and a formula (6) of 0.046a0.188. In the formula (1), A is at least one kind of element selected from a group consisting of Sr and Ba.

According to one embodiment, there is provided a positive electrode including a positive electrode active material-including layer including a positive electrode active material, which includes a lithium-manganese oxide LiMn.sub.2-xM.sub.xO.sub.4, and a conductive agent. In the positive electrode active material-including layer, an average particle diameter d.sub.50 is within 2 m to 5 m, a particle diameter d.sub.10 and a particle diameter d.sub.90, where a cumulative frequency from a smaller side is, respectively, 10% and 90%, is within 0.5 m to 3 m and within 4 m to 10 m, respectively, in a particle size distribution. X, represented by X=(d.sub.50d.sub.10) /d.sub.50 is within 0.4 to 0.8. Y, represented by Y=(d.sub.90d.sub.50)/d.sub.90 is within 0.2 to 0.6.

A set of spherical inorganic particles having the particular property of being spontaneously individualized, both in dry state in the form of a powder and when they are dispersed in a matrix. The method for producing the particles, and the materials produced by including the particles in the matrices are also described.

According to one embodiment, an active material is provided. The active material includes orthorhombic system oxide represented by the following formula: Li.sub.xM1M2.sub.2O.sub.6. In this formula, 0x5, M1 is at least one selected from the group consisting of Fe and Mn, and M2 is at least one selected from the group consisting of Nb, Ta and V.

Materials are presented of the formula:
A.sub.xM.sub.yM.sup.i.sub.ziO.sub.2d,
where A is sodium or a mixed alkali metal including sodium as a major constituent; x>0.5; M is a transition metal; y>0; M.sup.i, for i=1, 2, 3 . . . n, is a metal or germanium; z.sub.1>0 z.sub.i0 for each i=2, 3 . . . n; 0<d0.5;
the values of x, y, z.sub.i and d are such as to maintain charge neutrality; and the values of y, z.sub.i and d are such that y+z.sub.i>(2d). The formula includes compounds that are oxygen deficient. Further the oxidation states may or may not be integers i.e. they may be whole numbers or fractions or a combination of whole numbers and fractions and may be averaged over different crystallographic sites in the material. Such materials are useful, for example, as electrode materials in rechargeable battery applications.

A sintered ferrite magnet comprises a main phase of an M type Sr ferrite having a hexagonal crystal structure. An amount of Zn is 0.05 to 1.35 mass % in terms of ZnO and M1/M2 is 0.43 or less when an amount of a rare-earth element (R) is M1 in terms of mol and the amount of Zn is M2 in terms of mol.

Methods, systems, and devices are disclosed for fabricating and implementing optically absorbing coatings. In one aspect, an optically selective coating includes a substrate formed of a solar energy absorbing material, and a nanostructure material formed over the substrate as a coating capable of absorbing solar energy in a selected spectrum and reflecting the solar energy in another selected spectrum. A concentrating solar power (CSP) system includes heat transfer fluids (HTFs); thermal energy storage system (TES); and solar receivers in communication with HTFs and including a light absorbing coating layer based on cobalt oxide nanoparticles.