Abstract: In an aspect, a ferrite composition comprises a BiRuCo-M-type ferrite having the formula Me1-xBixCoyRuzFe12-tO19, wherein Me is at least one of Sr, Pb, or Ba; x is 0.01 to 0.5; y is 0.1 to 2; z is 0 to 4, and t is 0 to 4; wherein the Co can be at least partially replaced by at least one of Zn, Cu, or Mg by an amount of less than y, and the Ru can be at least partially replaced by at least one of Ti, Sn, or Zr, where the substitution amount is not more than z or is less than z.

Abstract: In an aspect, an R-type ferrite has the formula: Me?3Me2TiFe12O25, wherein Me? is at least one of Ba2+ or Sr2+ and Me is at least one of Co2+, Mg2+, Cu2+, or Zn2+. In another aspect, a composite or an article comprises the R-type ferrite. In yet another aspect, a method of making a R-type ferrite comprises milling ferrite precursor compounds comprising oxides of at least Fe, Ti, Me, and Me?, to form an oxide mixture; wherein Me? comprises at least one of Ba2+ or Sr2+; Me is at least one of Co2+, Mg2+, Cu2+, or Zn2+; and calcining the oxide mixture in an oxygen or air atmosphere to form the R-type ferrite.

Abstract: In an aspect, a multiphase ferrite comprises a Co2W phase that is optionally doped with Ru; a CFO phase having the formula Mer“Co1?rFe2+zO4, 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 BaCox+yRuyFe12?(2/3)x?2yO19, 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.

Abstract: In an aspect, a Co2Z-type ferrite comprises oxides of at least Me, Co, Mo, Li, and Fe; wherein Me is at least one of Ba or Sr. In another aspect, the Co2Z-type ferrite comprises a Z-type hexaferrite an amount of lithium molybdate. In another aspect, the Co2Z-type ferrite has a formula Li2MoO4.BaxSr3-xCo2+y?zMe?yMe?zFe24-2y-mO41, wherein Me? is at least one of Ti, Mo, Ru, Ir, Zr, or Sn; Me? is at least one of Zn, Mn, or Mg; x is 0 to 3; y is 0 to 1.8; z is 0 to 1.8; and m is ?4 to 4. In yet another aspect, a method of making a Co2Z-type ferrite comprises milling an initial Co2Z-type ferrite and Li2MoO4 to form a mixed ferrite; and calcining the mixed ferrite to form the Co2Z-type ferrite.

Abstract: In an aspect, a ferrite composition can comprise a SbCo—M-type ferrite having the formula: Me1-xSbxCoy+xM?yFe12-x-2yO19, 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 SbCo—M-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.

Abstract: In an aspect, a ferrite composition comprises a Ru—Co2Z ferrite having the formula: (Ba3-xMx)Co2(M?Ru)yFe24-2y-zO41, wherein M is at least one of Sr, Pb, or Ca; M? is at least one of Co, Zn, Mg, or Cu; x is 1 to 3; y is greater than 0 to 2; and z is ?4 to 4. In another aspect, an article comprises the ferrite composition. In yet another aspect, method of making the ferrite composition comprises mixing ferrite precursor compounds comprising Fe, Ba, Co, and Ru; and sintering the ferrite precursor compounds in an oxygen atmosphere to form the Ru—Co2Z ferrite.

Abstract: A polycrystalline ferrite composition comprises a formula of M5Me2Ti3Fe12O31, wherein M is Ba2+, Se+, or a combination thereof; and Me is Mg2+, Zn2+, Cu2+, Co2+, or a combination thereof; and has an average grain size of 1 micrometer to 100 micrometers. A composite comprises a polymer matrix; and the polycrystalline ferrite composition. Methods of making the polycrystalline ferrite composition and the composite are also disclosed.

Abstract: In an aspect, a ferrite composition comprises a BiRuCo-M-type ferrite having the formula Me1-xBixCoyRuzFe12-tO19, wherein Me is at least one of Sr, Pb, or Ba; x is 0.01 to 0.5; y is 0.1 to 2; z is 0 to 4, and t is 0 to 4; wherein the Co can be at least partially replaced by at least one of Zn, Cu, or Mg by an amount of less than y, and the Ru can be at least partially replaced by at least one of Ti, Sn, or Zr, where the substitution amount is not more than z or is less than z.

Abstract: In an aspect, a ferrite composition comprises a Ru—Co2Z ferrite having the formula: (Ba3-xMx)Co2(M?Ru)yFe24-2y-zO41, wherein M is at least one of Sr, Pb, or Ca; M? is at least one of Co, Zn, Mg, or Cu; x is 1 to 3; y is greater than 0 to 2; and z is ?4 to 4. In another aspect, an article comprises the ferrite composition. In yet another aspect, method of making the ferrite composition comprises mixing ferrite precursor compounds comprising Fe, Ba, Co, and Ru; and sintering the ferrite precursor compounds in an oxygen atmosphere to form the Ru—Co2Z ferrite.

Abstract: In an aspect, a multiphase ferrite comprises a Co2W phase that is optionally doped with Ru; a CFO phase having the formula Mer“Co1?rFe2+zO4, 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 BaCox+yRuyFe12?(2/3)x?2yO19, 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.