The piezoelectric composition is represented by the following Chemical Formula (1):
x[Bi.sub.mFeO.sub.3]-y[Ba.sub.mTiO.sub.3]-z[Bi.sub.mAlO.sub.3](1)
wherein 0.5x0.7995, 0.2y0.4, 0.0005z0.1, x+y+z=1, 0.96m1.04.

Provided are: an Mn ferrite powder characterized by including a plurality of ferrite particles, having a volume-average particle diameter of 1-10 m, and having a 2.106 m volume-based cumulative distribution (sieved) of 0.1-50.0 vol %; and a resin composition characterized by including said powder and a resin material.

A method for producing a MnZn ferrite core used at a frequency of 1 MHz or more and an exciting magnetic flux density of 75 mT or less, the MnZn ferrite comprising 53-56% by mol of Fe (calculated as Fe.sub.2O.sub.3), and 3-9% by mol of Zn (calculated as ZnO), the balance being Mn (calculated as MnO), as main components, and 0.05-0.4 parts by mass of Co (calculated as Co.sub.3O.sub.4) as a sub-component, per 100 parts by mass in total of the main components (calculated as the oxides); comprising a step of molding a raw material powder for the MnZn ferrite to obtain a green body; a step of sintering the green body and cooling it to a temperature of lower than 150 C. to obtain a sintered body of MnZn ferrite; and a step of conducting a heat treatment comprising heating the sintered body of MnZn ferrite to a temperature meeting Condition 1 of 200 C. or higher, and Condition 2 of (Tc90) C. to (Tc+100) C., wherein Tc is a Curie temperature ( C.) calculated from the percentages by mol of Fe.sub.2O.sub.3 and ZnO contained in the main components of the MnZn ferrite, keeping the sintered body at the above temperature for a predetermined period of time, and then cooling the sintered body from the keeping temperature at a speed of 50 C./hour or less.

A method for producing a MnZn ferrite core used at a frequency of 1 MHz or more and an exciting magnetic flux density of 75 mT or less, the MnZn ferrite comprising 53-56% by mol of Fe (calculated as Fe.sub.2O.sub.3), and 3-9% by mol of Zn (calculated as ZnO), the balance being Mn (calculated as MnO), as main components, and 0.05-0.4 parts by mass of Co (calculated as Co.sub.3O.sub.4) as a sub-component, per 100 parts by mass in total of the main components (calculated as the oxides); comprising a step of molding a raw material powder for the MnZn ferrite to obtain a green body; a step of sintering the green body and cooling it to a temperature of lower than 150 C. to obtain a sintered body of MnZn ferrite; and a step of conducting a heat treatment comprising heating the sintered body of MnZn ferrite to a temperature meeting Condition 1 of 200 C. or higher, and Condition 2 of (Tc90) C. to (Tc+100) C., wherein Tc is a Curie temperature ( C.) calculated from the percentages by mol of Fe.sub.2O.sub.3 and ZnO contained in the main components of the MnZn ferrite, keeping the sintered body at the above temperature for a predetermined period of time, and then cooling the sintered body from the keeping temperature at a speed of 50 C./hour or less.

A piezoelectric composition comprises a plurality of crystal particles, wherein the piezoelectric composition includes bismuth, iron, barium, titanium, and oxygen; the crystal particle include a core and a shell having a contents of bismuth higher than that in the core and covering the core; and the total area of the cross sections of the cores exposed to the cross section of the piezoelectric composition is expressed as S.sub.CORE, the total area of the cross sections of the shells exposed to the cross section of the piezoelectric composition is expressed as S.sub.SHELL, and 100.Math.S.sub.CORE/(S.sub.CORE+S.sub.SHELL) is 50 to 90.

A carrier core material is represented by a composition formula M.sub.XFe.sub.3-XO.sub.4 (where M is at least one type of metal element selected from Mg, Mn, Ca, Ti, Cu, Zn and Ni, 0<X<1), in which part of M and/or Fe is substituted with Sr and formed of ferrite particles, and in the carrier core material, a Sr content is equal to or more than 2500 ppm but equal to or less than 12000 ppm, the amount of Sr eluted with pure water at a temperature of 25 C. is equal to or less than 50 ppm, an apparent density is equal to or more than 1.85 g/cm.sup.3 but equal to or less than 2.25 g/cm.sup.3 and magnetization .sub.1k when a magnetic field of 79.5810.sup.3 A/m (1000 oersteds) is applied is equal to or more than 63 Am.sup.2/kg but equal to or less than 75 Am.sup.2/kg.

A positive electrode active material for a sodium ion battery includes a sodium complex oxide of the formula Na.sub.4(M.sup.1.sub.aM.sup.2.sub.1a).sub.2O.sub.5 having an orthorhombic crystal structure, wherein M.sup.1 and M.sup.2 are each independently Ti, Cr, Fe, Co, Ni, Mn, V, or a combination there of provided that M.sup.1 and M.sup.2 are different from each other; and 0a1.

The invention relates to a method for producing magnetite with a purity of no less than 90% and higher than 98%, by oxidation of pulverized wustite (iron oxide), at temperatures ranging from 200 C. to 800 C., with the addition of water in liquid or steam form, in counter-current or concurrently, in an externally heated reaction chamber with a controlled atmosphere. The amount of water used to oxidize the wustite being 60 to 500 ml per kilogram of wustite, the grains of wustite powder are injected into the reaction chamber having a size no greater than 100 m for optimal reaction.

Cathode materials for lithium ion batteries, lithium ion batteries incorporating the cathode materials, and methods of operating the lithium ion batteries are provided. The materials are composed of lithium metal oxides that include two different metals.

In an aspect, a multiphase ferrite comprises a Co.sub.2W phase that is optionally doped with Ru; a CFO phase having the formula Me.sub.rCo.sub.1rFe.sub.2+zO.sub.4, wherein Me is at least one of Ni, Zn, or Mg, r is 0 to 0.5, and z is 0.5 to 6 0.5; and a CoRu-BaM phase having the formula BaCo.sub.x+yRu.sub.yFe.sub.12(2/3)x2yO.sub.19, wherein x is 0 to 2, y is 0.01 to 2; and the Ba can be partially replaced by at least one of Sr or Ca. In another aspect, a composite can comprise a polymer and the multiphase ferrite. In yet another aspect, a method of making a multiphase ferrite can comprise mixing and grinding a CoRu-BaM phase ferrite and a CFO phase ferrite to form a mixture; and sintering the mixture in an oxygen atmosphere to form the multiphase ferrite.