Disclosed are a composite material and a method for preparing the same. The composite material is consisted of TiO.sub.2 and BaZn.sub.1.2Co.sub.0.8Fe.sub.16O.sub.27. The composite material of the invention has the advantages of high absorption frequency band, good compatibility and wide frequency band, and it is applicable for the shell protection material of a mobile phone or a TV set, thereby absorbing the electromagnetic wave band that is the most harmful to human bodies, without influencing the normal communication function of an electronic device, for example, a mobile phone.

A Co.sub.2Z hexaferrite composition is provided containing molybdenum and one or both of barium and strontium, having the formula (Ba.sub.2Sr.sub.(3-Z)Co.sub.(2+X))Mo.sub.xFe.sub.(y-2x)O.sub.41 where x=0.01 to 0.20; y=20 to 24; and z=0 to 3. The composition can exhibit high permeabilities and equal or substantially equal values of permeability and permittivity while retaining low magnetic and dielectric loss tangents and loss factors. The composition is suitable for high frequency applications such as ultrahigh frequency and microwave antennas and other devices.

A method for forming a positive electrode active material that can be used for a lithium ion battery having excellent discharge characteristics even in a low-temperature environment is provided. The method includes a first step in which lithium cobalt oxide with a median diameter (D50) of less than or equal to 10 m is heated at a temperature higher than or equal to 700 C. and lower than or equal to 1000 C. for longer than or equal to 1 hour and shorter than or equal to 5 hours, a second step in which a first mixture is formed by mixing a fluorine source and a magnesium source to the lithium cobalt oxide subjected to the first step, a third step in which the first mixture is heated at a temperature higher than or equal to 800 C. and lower than or equal to 1100 C. for longer than or equal to 1 hour and shorter than or equal to 10 hours, a fourth step in which a second mixture is formed by mixing a nickel source and an aluminum source to the first mixture subjected to the third step, and a fifth step in which the second mixture is heated at a temperature higher than or equal to 800 C. and lower than or equal to 950 C. for longer than or equal to 1 hour and shorter than or equal to 5 hours.

A positive electrode active material includes: a particle including a lithium composite oxide; a first layer that is provided on a surface of the particle and includes a lithium composite oxide; and a second layer that is provided on a surface of the first layer. The lithium composite oxide included in the particle and the lithium composite oxide included in the first layer have the same composition or almost the same composition, the second layer includes an oxide or a fluoride, and the lithium composite oxide included in the first layer has lower crystallinity than the lithium composite oxide included in the particle.

An electromagnetic effect material includes as a primary component, a polycrystalline oxide ceramic containing at least Sr, Co, and Fe. In the polycrystalline oxide ceramic, the crystal c-axis is oriented in a predetermined direction, and the degree of orientation of the c-axis is 0.2 or more by a Lotgering method. A component substrate is formed of this electromagnetic effect material.

A positive electrode active material has a small difference in a crystal structure between the charged state and the discharged state. For example, the crystal structure and volume of the positive electrode active material, which has a layered rock-salt crystal structure in the discharged state and a pseudo-spinel crystal structure in the charged state at a high voltage of approximately 4.6 V, are less likely to be changed by charging and discharging as compared with those of a known positive electrode active material. In order to form the positive electrode active material having the pseudo-spinel crystal structure in the charged state, it is preferable that a halogen source such as a fluorine and a magnesium source be mixed with particles of a composite oxide containing lithium, a transition metal, and oxygen, which is synthesized in advance, and then the mixture be heated at an appropriate temperature for an appropriate time.

A positive electrode active material has a small difference in a crystal structure between the charged state and the discharged state. For example, the crystal structure and volume of the positive electrode active material, which has a layered rock-salt crystal structure in the discharged state and a pseudo-spinel crystal structure in the charged state at a high voltage of approximately 4.6 V, are less likely to be changed by charging and discharging as compared with those of a known positive electrode active material. In order to form the positive electrode active material having the pseudo-spinel crystal structure in the charged state, it is preferable that a halogen source such as a fluorine and a magnesium source be mixed with particles of a composite oxide containing lithium, a transition metal, and oxygen, which is synthesized in advance, and then the mixture be heated at an appropriate temperature for an appropriate time.

A sodium-ion battery includes a cathode comprising sodium; and an anode composition comprising a material having the formula: A.sub.aB.sub.bC.sub.cD.sub.dO, where A is an alkali metal, alkaline earth metal, or a combination thereof, where B is titanium, C is vanadium, D is one or more transition metal element other than titanium or vanadium, a+b+c+d1, a0, b+c>0, b0, c0, d>0, and where the material comprises a ilmenite structure, triclinic VFeO.sub.4 structure, cubic Ca.sub.5Co.sub.4(VO.sub.4).sub.6 structure, dichromate structure, orthorhombic -CoV.sub.3O.sub.8 structure, brannerite structure, thortveitite structure, orthorhombic -CrPO.sub.4 structure, or the pseudo rutile structure.

Rapid, reversible redox activity may be accomplished at significantly reduced temperatures, as low as about 200 C., from epitaxially stabilized, oxygen vacancy ordered SrCoO.sub.2.5 and thermodynamically unfavorable perovskite SrCoO.sub.3-. The fast, low temperature redox activity in SrCoO.sub.3- may be attributed to a small Gibbs free energy difference between the two topotactic phases. Epitaxially stabilized thin films of strontium cobaltite provide a catalyst adapted to rapidly transition between oxidation states at substantially low temperatures. Methods of transitioning a strontium cobaltite catalyst from a first oxidation state to a second oxidation state are described.

In an aspect, a ferrite composition can comprise a SbCoM-type ferrite having the formula: Me.sub.1-xSb.sub.xCo.sub.y+xM.sub.yFe.sub.12-x-2yO.sub.19, wherein Me is at least one of Sr, Pb, or Ba; M is at least one of Ti, Zr, Ru, or Ir; x is 0.001 to 0.3; and y is 0.8 to 1.3. In another aspect, a method of making the ferrite composition comprises mixing ferrite precursor compounds comprising Me, Fe, Sb, Co, and M; and sintering the ferrite precursor compounds in an oxygen atmosphere to form the SbCoM-type ferrite. In yet another aspect, a composite comprises the ferrite composition and a polymer. In still another aspect, an article comprises the ferrite composition.