Mn-Zn Based Ferrite Material

Abstract
For the purpose of providing a Mn—Zn based ferrite material that is small in magnetic field degradation in high frequency bands of 1 MHz or more, the Mn—Zn based ferrite material includes: as main constituents, Fe2O3: 53 to 56 mol %, ZnO: 7 mol % or less (inclusive of 0 mol %), and the balance: MnO; and as additives, Co: 0.15 to 0.65% by weight in terms of Co3O4, Si: 0.01 to 0.045% by weight in terms of SiO2 and Ca: 0.05 to 0.40% by weight in terms of CaCO3; wherein the δ value (the cation defect amount) defined in the present specification satisfies the relation 3×10−3≦δ≦7×10−3; and the mean grain size is larger than 8 μm and 15 μm or less.
Description

BRIEF DESCRIPTION OF THE DRAWINGS


FIG. 1 is a graph showing a relation between a cation defect amount δ and a magnetic field degradation rate;



FIG. 2 is a graph showing a relation between a mean grain size and the magnetic field degradation rate;



FIG. 3 is a graph showing a relation between the amount of Fe2O3 and the magnetic field degradation rate;



FIG. 4 is a graph showing a relation between the amount of ZnO and the magnetic field degradation rate;



FIG. 5 is a graph showing a relation between the amount of Co3O4 and the magnetic field degradation rate;



FIG. 6 is a graph showing a relation between the amount of SiO2 and the magnetic field degradation rate; and



FIG. 7 is a graph showing a relation between the amount of CaCO3 and the magnetic field degradation rate.


Claims
  • 1. A Mn—Zn based ferrite material comprising: as main constituents,Fe2O3: 53 to 56 mol %;ZnO: 7 mol % or less (inclusive of 0 mol %); andthe balance: MnO; andas additives,Co: 0.15 to 0.65% by weight in terms of CO3O4;Si: 0.01 to 0.045% by weight in terms of SiO2; andCa: 0.05 to 0.40% by weight in terms of CaCO3;wherein:the δ value (the cation defect amount) in the following ferrite composition formula (1) satisfies the relation 3×10−3≦δ≦7×10−3; andthe mean grain size is larger than 8 μm and 15 μm or less;the composition formula (1) being represented as follows: (Zna2+, Tib4+, Mnc2+, Mnd3+, Fee2+, Fef3+, Cog2+, Coh3+)3O4+δ  Formula (1)wherein a+b+c+d+e+f+g+h=3, and δ=a+2b+c+(3/2)d+e+(3/2)f+g+(3/2)h−4 with the proviso that g:h=1:2.
  • 2. The Mn—Zn based ferrite material according to claim 1, wherein the δ value satisfies the relation 3×10−3≦δ≦5×10−3.
  • 3. The Mn—Zn based ferrite material according to claim 1, wherein the δ value satisfies the relation 3×10−3≦δ≦4.5×10−3.
  • 4. The Mn—Zn based ferrite material according to claim 1, wherein: the power loss thereof is 3200 [kW/m3] or less in the temperature range from room temperature to 125° C. at an excitation magnetic flux density of 50 mT and a measurement frequency of 2 MHz; anda magnetic field degradation rate is 100% or less wherein the magnetic field degradation rate is the rate of the increase of the power loss immediately after the excitation approximately up to the saturation magnetic flux density relative to the power loss before the excitation.
  • 5. The Mn—Zn based ferrite material according to claim 1, wherein the amount of ZnO is 2 to 7 mol %.
  • 6. The Mn—Zn based ferrite material according to claim 1, wherein the amount of Co is 0.15 to 0.50% by weight in terms of Co3O4.
  • 7. The Mn—Zn based ferrite material according to claim 1, wherein the amount of Si is 0.01 to 0.03% by weight in terms of SiO2.
  • 8. The Mn—Zn based ferrite material according to claim 1, wherein the amount of Ca is 0.10 to 0.30% by weight in terms of CaCO3.
  • 9. The Mn—Zn based ferrite material according to claim 1, wherein the amount of Co is 0.15 to 0.30% by weight in terms of CO3O4, the amount of Si is 0.01 to 0.02% by weight in terms of SiO2, and the amount of Ca is 0.1 to 0.2% by weight in terms of CaCO3.
  • 10. The Mn—Zn based ferrite material according to claim 9, wherein the δ value satisfies the relation 3×10−3≦δ≦5×10−3.
  • 11. The Mn—Zn based ferrite material according to claim 2, wherein: the power loss thereof is 3200 [kW/m3] or less in the temperature range from room temperature to 125° C. at an excitation magnetic flux density of 50 mT and a measurement frequency of 2 MHz; anda magnetic field degradation rate is 100% or less wherein the magnetic field degradation rate is the rate of the increase of the power loss immediately after the excitation approximately up to the saturation magnetic flux density relative to the power loss before the excitation.
Priority Claims (1)
Number Date Country Kind
2006-093716 Mar 2006 JP national