Mo-doped Co2Z-type ferrite composite material for use ultra-high frequency antennas

Patent metadata

Field	Value
Publication number	US-10766786-B2
Application number	US-201615546891-A
Country	US
Kind code	B2
Filing date	Feb 1, 2016
Priority date	Jan 30, 2015
Publication date	Sep 8, 2020
Grant date	Sep 8, 2020

Abstract

A Co2Z hexaferrite composition is provided containing molybdenum and one or both of barium and strontium, having the formula (Ba2Sr(3-Z)Co(2+X))MoxFe(y-2x)O41 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.

First claim

What is claimed is:

1. A hexaferrite composition comprising iron, cobalt, one or both of barium and strontium, and molybdenum, wherein said ferrite composition comprises a Z-type hexaferrite phase, having the formula
(Ba z Sr (3-z) )Co (2+x) Mo x Fe (y-2x) O 41

where x=0.01 to 0.20;
y=20 to 24; and
z=0 to 3.

2. The hexaferrite composition of claim 1 , wherein x=0.08 to 0.15.

3. The hexaferrite composition of claim 1 , wherein x=0.10 to 0.12.

4. The hexaferrite composition of claim 1 , wherein the hexaferrite composition has a real permeability at least 3.0 over a frequency range of 0.1 to 3.0 GHz.

5. The hexaferrite composition of claim 1 , wherein the hexaferrite composition has a real permeability at least 7.0 over a frequency range of 0.1 to 3.0 GHz.

6. The hexaferrite composition of claim 1 , wherein the hexaferrite composition has a real permeability ranging from 7.0 to 12.0 over a frequency range of 0.1 to 3.0 GHz.

7. The hexaferrite composition of claim 1 , wherein z=1.2 to 3.0, and the hexaferrite composition has a real permeability ranging from 8.0 to 12.0 over a frequency range of about 0.1 GHz to at least 1.0 GHz.

8. The hexaferrite composition of claim 1 , wherein z=0 to 0.5, and the hexaferrite composition has a real permeability ranging from 2.0 to 4.0 over a frequency range of about 0.1 GHz to about 3.0 GHz.

9. The hexaferrite composition of claim 1 , wherein the hexaferrite composition has a real permittivity at least 6.0 over a frequency range of 0.1 to 3.0 GHz.

10. The hexaferrite composition of claim 1 , wherein the hexaferrite composition has a real permittivity at least 8.0 over a frequency range of 0.1 to 3.0 GHz.

11. The hexaferrite composition of claim 1 , wherein the hexaferrite composition has a real permittivity ranging from 6.0 to 18.0 over a frequency range of 0.1 to 10.0 GHz.

12. The hexaferrite composition of claim 1 , wherein a real permittivity of the hexaferrite composition is equal to a real permeability of the hexaferrite composition within 10%.

13. The hexaferrite composition of claim 1 , wherein the hexaferrite composition has a characteristic impedance matching an impedance of free space within 3%.

14. The hexaferrite composition of claim 1 , wherein the hexaferrite composition has a dielectric loss tangent, tan δ ε , less than 0.02 at a frequency of 0.1 to 0.8 GHz.

15. The hexaferrite composition of claim 1 , wherein the hexaferrite composition has a dielectric loss tangent, tan δ ε , less than 0.16 at a frequency of 0.1 to 1.0 GHz.

16. The hexaferrite composition of claim 1 , wherein the hexaferrite composition has a magnetic loss tangent tan δ μ approximately 0.1 at 0.4 GHz.

17. The hexaferrite composition of claim 1 , wherein the hexaferrite composition has a magnetic loss tangent tan δ μ less than 0.3 at a frequency of 0.1 to 0.8 GHz.

18. The hexaferrite composition of claim 1 , wherein the hexaferrite composition has a magnetic loss tangent tanδ μ less than 0.95 at a frequency of 0.1 to 3.5 GHz.

19. The hexaferrite composition of claim 1 , wherein the hexaferrite composition has a magnetic loss tangent, tan δ μ , ranging from 0.1 to 1.0 over a frequency range of 0.1 to 1.0 GHz.

20. The hexaferrite composition of claim 1 , wherein the hexaferrite composition has a dielectric loss factor tan δ ε /ε′ less than 0.001 at a frequency of 0.8 GHz.

21. The hexaferrite composition of claim 1 , wherein the hexaferrite composition has a magnetic loss factor tan δ μ /μ′ less than 0.03 at a frequency of 0.8 GHz.

22. An article comprising the hexaferrite composition of claim 1 .

23. The article of claim 22 , wherein the article is an antenna, filter, inductor, circulator, or phase shifter.

24. The article of claim 22 , wherein the article is a microwave antenna.

25. The article of claim 24 , wherein the article is an antenna operable at a frequency equal to or greater than 0.1 GHz.

26. The article of claim 24 , wherein the article is an antenna operable at a frequency equal to or greater than 0.3 GHz.

27. The article of claim 24 , wherein the article is an antenna operable at 0.1 to 1.5 GHz.

28. The article of claim 24 , wherein the article is an antenna operable at 0.3 to 1.0 GHz.

29. The article of claim 22 , further comprising a second hexaferrite composition comprising a Z-type hexaferrite phase having the formula
(Ba z Sr (3-z) )Co (2+x) Mo x Fe (y-2x) O 41

where x=0.01 to 0.20;
y=20 to 24; and
z=0 to 3; and

wherein the amount of Ba and the amount of Sr in the hexaferrite composition and the second hexaferrite composition differ.

30. The article of claim 29 , wherein a cutoff frequency of the second hexaferrite composition is higher than a cutoff frequency of the hexaferrite composition.

31. The article of claim 29 , wherein the hexaferrite composition has a real permeability ranging from 8.0 to 12.0 over a frequency range of about 0.1 GHz to at least 1.0 GHz, and the second hexaferrite composition has a real permeability ranging from 2.0 to 4.0 over a frequency range of about 0.1 GHz to about 3.0 GHz.

32. The article of claim 22 , wherein the article is a giant magnetoresistant device or a giant tunneling magnetoresistant device.

33. A method of making a hexaferrite composition comprising:
(a) providing hexaferrite phase precursor compounds comprising Fe, Ba, Co, and Mo,
(b) calcining the hexaferrite phase precursor compounds in air to form a material comprising a Z-type hexaferrite phase.

34. The method of claim 33 , wherein the hexaferrite phase precursor compounds comprise oxides of Fe, Ba, Co, and Mo.

35. The method of claim 33 , wherein the hexaferrite phase precursor compounds comprise MoO 2 , BaCO 3 , Co 3 O 4 , and Fe 2 O 3 .

36. The method of claim 33 , wherein the hexaferrite phase precursor compounds comprise 0 to 0.96 wt. % MoO 2 , 22.10 to 22.18 wt. % BaCO 3 , 6.02 to 6.59 wt. % Co 3 O 4 , and 70.35 to 71.8 wt. % Fe 2 O 3 .

37. The method of claim 33 , wherein in step (b), the precursor compounds are calcined at 1000 to 1300° C.

38. The method of claim 33 , further comprising:
(c) crushing the material formed in step (b) to form a powder mixture, and
(d) sintering the powder mixture.

39. The method of claim 38 , wherein the powder mixture is sintered at 1200 to 1280° C. for 4 to 20 hours in an oxygen atmosphere.

40. The method of claim 38 , further comprising forming the powder mixture into a compact prior to step (d).

41. The method of claim 38 , further comprising adding a binder to the powder mixture.

42. The method of claim 41 , wherein the binder is selected from the group consisting of a polyvinyl alcohol, methyl cellulose, polyethylene glycol, and poly(alkylene carbonate).

43. The method of claim 41 , wherein the binder is polyvinyl alcohol comprising 8% to 12% by weight of the powder mixture.

44. The method of claim 38 , further comprising:
(e) crushing the material formed in step (d) to form a powder mixture; and
(f) annealing the powder mixture formed in step (e).

45. The method of claim 44 , wherein the

Assignees

• Univ Northeastern
• Rogers Corp

Inventors

• Chen Yajie
• Harris Vincent

Classifications

• C01G51/82 Primary

  Compounds containing cobalt, with or without oxygen or hydrogen, and containing two or more other elements · CPC title

• C01G39/006 Primary

  Compounds containing molybdenum, with or without oxygen or hydrogen, and containing two or more other elements · CPC title

• C04B2235/6585

  at an oxygen percentage above that of air · CPC title

• C04B2235/767

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

• C01G49/0036

  containing one alkaline earth metal, magnesium or lead · CPC title