Textured planar m-type hexagonal ferrites and methods of use thereof

Patent metadata

Field	Value
Publication number	US-11508503-B2
Application number	US-201916378676-A
Country	US
Kind code	B2
Filing date	Apr 9, 2019
Priority date	Apr 12, 2018
Publication date	Nov 22, 2022
Grant date	Nov 22, 2022

Abstract

A grain-oriented M-type hexagonal ferrite has the formula MeFe 12 O 19 , and a dopant effective to provide planar magnetic anisotropy and magnetization in a c-plane, or a cone anisotropy, in the hexagonal crystallographic structure wherein Me is Sr + , Ba 2+ or Pb 2+ , and wherein greater than 30%, preferably greater than 80%, of c-axes of the ferrite grains are aligned perpendicular to the c-plane.

First claim

The invention claimed is:

1. A grain-oriented M-type hexagonal ferrite having the formula
MeFe 12 O 19 ,

and a dopant effective to provide planar magnetic anisotropy and magnetization in a c-plane, or a cone anisotropy, in the hexagonal crystallographic structure, wherein Me is Sr + , Ba 2+ or Pb 2+ , and
wherein greater than 30% of grains of the ferrite are aligned along the c-axis of the crystal structure, perpendicular to the c-plane;
wherein the dopant comprisese Co 2+ /Ti 4+ , Co 2+ /Zr 4+ , Co 2+ /Sn 4+ , Co 2+ /Ir 4′ , Bi 2+ /Co 2+ /Ti 4+ , Bi 2+ /Co 2+ /Zr 4+ , Bi 2+ /Co 2+ /Sn 4+ , or a combination thereof.

2. The grain-oriented M-type hexagonal ferrite of claim 1 , having the formula Bi x —Ba 1−x (CoTi) y Fe 12−2y O 19 (x=0-0.8, y=0.5-1.5), Ba(CoTi) x Fe 12−2x O 19 (x=0.5-1.5), Ba(CoZr) x Fe 12−2x O 19 (x=0.5-1.5), Ba(CoSn) x Fe 12−2x O 19 (x=0.5-1.5), Ba(CoIr) x Fe 12−2x O 19 (x=0.5-1.5), Bi x Sr 1−x (CoTi) y —Fe 12−2y O 19 (x=0-0.8, y=0.5-1.5), Sr(CoTi) x Fe 12−2x O 19 (x=0.5-1.5), Sr(CoZr) x Fe 12−2x O 19 (x=0.5-1.5), Sr(CoSn) x Fe 12−2x O 19 (x=0.5-1.5), or Pb(CoTi) x Fe 12−2x O 19 (x=0.5-1.5).

3. The grain-oriented M-type hexagonal ferrite of claim 1 , having the formula Bi x Ba 1−x (CoTi) y Fe 12−2y O 19 (x=0-0.8, y=0.5-1.5), Ba(CoTi) x Fe 12−2x O 19 (x=0.5-1.5), Ba(CoZr) x Fe 12−2x O 19 (x=0.5-1.5), or Ba(CoSn) x Fe 12−2x O 19 (x=0.5-1.5).

4. The grain-oriented M-type hexagonal ferrite of claim 1 , wherein Me is Ba 2+ with substitution of Sr for Ba in part, and having the formula (Bi x Sr y Ba 1−x−y )(CoTi) z Fe 12−2z O 19 (x=0-0.8, y=0-1, z=0.5-2.0).

5. The grain-oriented M-type hexagonal ferrite having the formula
MeFe 12 O 19 ,

and a dopant effective to provide planar magnetic anisotropy and magnetization in a c-plane, or an easy cone anisotropy, in the hexagonal crystallographic structure, wherein Me is Sr 2+ , Ba 2+ or Pb 2+ , and
wherein greater than 30% of grains of the ferrite are aligned along the c-axis of the crystal structure, perpendicular to the c-plane,
wherein the grain-oriented M-type hexagonal ferrite has at least one of
an in-plane permeability of greater than 50 over an operating frequency of 50 MHz-300 MHz;
a magnetic loss tangent of less than 0.5 at 100 MHz;
a dielectric loss tangent of less than 0.02 over 0-300 MHz; or
a dielectric constant that is 10-30 over 30-300 MHz.

6. The grain-oriented M-type hexagonal ferrite of claim 5 , wherein the grain-oriented M-type hexagonal ferrite has
a magnetic loss tangent of less than 0.2 over 30-300 MHz; and
a dielectric loss tangent of less than 0.05 over 30-300 MHz.

7. The grain-oriented M-type hexagonal ferrite of claim 5 , wherein the grain-oriented M-type hexagonal ferrite has
an in-plane permeability of greater than 80 at an operating frequency over 50-300 MHz; and
a magnetic loss tangent of less than 0.2 at 100 MHz.

8. The grain-oriented M-type hexagonal ferrite of claim 1 , wherein the hexagonal ferrite has a sintered density of at least 85% of a theoretical density.

9. The grain-oriented M-type hexagonal ferrite of claim 1 , wherein the grain size in the c-plane is up to 300 μm.

10. An article comprising the grain-oriented M-type hexagonal ferrite of claim 1 .

11. The article of claim 10 , wherein the article is an inductor, a perpendicular magnetic record, an antenna, a microwave absorber, an electromagnetic interference suppressor, or a shielding material.

12. A wireless power device or near-field communication device comprising the shielding material of claim 11 .

13. A method of making a doped, grain-oriented M-type hexagonal ferrite of claim 1 , the method comprising
preparing a ferrite of the formula
MeFe 12 O 19

comprising a dopant effective to provide planar magnetic anisotropy and magnetization in the c-plane, or a cone anisotropy, wherein Me is Sr + , Ba 2+ or Pb 2+ ;
aligning the ferrite such that greater than 30% of grains of the ferrite are aligned along the c-axis of the crystal structure perpendicular to the c-plane, to provide the doped, grain-oriented M-type hexagonal ferrite; and
optionally sintering the doped, grain-oriented M-type hexagonal ferrite at a temperature of greater than 800° C. to provide a sintered material having a density of at least 85% of a theoretical density;
wherein the dopant comprises Co 2+ /Ti 4+ , Co 2+ /Zr 4+ , Co 2+ /Sn 4+ , Co 2+ /Ir 4+ , Bi 2+ /Co 2+ /Ti 4+ , Bi 2+ /Co 2+ /Zr 4+ , Bi 2+ /Co 2+ /Sn 4+ , or a combination thereof.

14. The method of claim 13 , wherein the dopant is provided by substituting a portion of the Fe with CoTi, CoZr, or CoSn.

15. The method of claim 13 , wherein preparing the ferrite comprises calcining a dry powder comprising a MeFe 12 O 19 precursor, a sol-gel process, a molten salt process, a co-precipitation process, a hydrothermal process, a sol gel hydrothermal process, or another chemical synthesis process.

16. The method of claim 13 , wherein aligning the ferrite comprises applying a rotating in-plane magnetic field to the ferrite while applying vertical mechanical pressure to the ferrite, applying a mechanical shearing force to the ferrite with or without applying a magnetic field applied, or a combination thereof.

17. The method of claim 16 , wherein aligning the ferrite comprises applying a rotating in-plane magnetic field having a magnetic field has a strength of greater than 2000 Oe.

18. The method of claim 13 , comprising, during aligning the ferrite, shaping the grain-oriented M-type hexagonal ferrite.

19. The method of claim 13 , comprising, prior to sintering, cutting the grain-oriented M-type hexagonal ferrite to a specified dimension.

Assignees

• Rogers Corp

Inventors

• Chen Yajie
• Ring Kevin
• Zhang Li
• White Michael S

Classifications

• H01F1/36

  in the form of particles {(H01F1/346, H01F1/348 and H01F1/38 take precedence)} · CPC title

• C04B2235/767

  Hexagonal symmetry, e.g. beta-Si3N4, beta-Sialon, alpha-SiC or hexa-ferrites · CPC title

• C04B2235/3289

  Noble metal oxides · CPC title

• C04B2235/3232

  Titanium oxides or titanates, e.g. rutile or anatase · CPC title

• C04B2235/3244

  Zirconium oxides, zirconates, hafnium oxides, hafnates, or oxide-forming salts thereof · CPC title