Radiofrequency and other electronic devices formed from enhanced resonant frequency hexaferrite materials

Patent metadata

Field	Value
Publication number	US-11245169-B2
Application number	US-202017088422-A
Country	US
Kind code	B2
Filing date	Nov 3, 2020
Priority date	Dec 7, 2010
Publication date	Feb 8, 2022
Grant date	Feb 8, 2022

Abstract

Radiofrequency and other electronic devices can be formed from textured hexaferrite materials, such as Z-phase barium cobalt ferrite Ba3Co2Fe24O41 (Co2Z) having enhanced resonant frequency. The textured hexaferrite material can be formed by sintering fine grain hexaferrite powder at a lower temperature than conventional firing temperatures to inhibit reduction of iron. The textured hexaferrite material can be used in radiofrequency devices such as circulators or telecommunications systems.

First claim

What is claimed is:

1. A method of forming an enhanced resonant frequency ferrite material, the method comprising:
forming a fine gram hexagonal ferrite powder comprising a Z-phase barium cobalt hexagonal ferrite material having a formula Ba 3 Co 2 Fe 24 O 41 , the hexagonal ferrite powder having a surface area of greater than 8 m 2 /g, an average particle size of between 300-600 nm, and a grain size between about five micrometers and one millimeter in diameter; and
firing the hexagonal ferrite powder at a sintering temperature between 1100 and 1150° C.

2. The method of claim 1 wherein the hexagonal ferrite powder has a surface area of greater than about 15 m 2 /g.

3. The method of claim 1 wherein the hexagonal ferrite powder has a surface area of between 8 and about 15 m 2 /g.

4. The method of claim 1 further comprising magnetically texturing the barium cobalt hexagonal ferrite material.

5. The method of claim 4 wherein the magnetically texturing occurs in a rotating magnetic field.

6. The method of claim 1 wherein the forming comprises zeta-milling.

7. The method of claim 1 further comprising incorporating the enhanced resonant frequency ferrite material into a magnetic isolator.

8. The method of claim 7 further comprising incorporating the magnetic isolator into a radio-frequency communication system.

9. A method of forming a ferrite material, the method comprising:
forming a fine grain hexagonal ferrite powder comprising a Z-phase barium cobalt hexagonal ferrite material having a formula Ba 3 Co 2 Fe 24 O 41 , the hexagonal ferrite powder having a surface area of greater than 6 m 2 /g, an average particle size of less than 1 micron; and
firing the hexagonal ferrite powder at a sintering temperature between 1100 and 1150° C.

10. The method of claim 9 further comprising magnetically texturing the barium cobalt hexagonal ferrite material.

11. The method of claim 10 wherein the magnetically texturing occurs in a rotating magnetic field.

12. The method of claim 9 wherein the forming comprises zeta-milling.

13. The method of claim 9 wherein the hexagonal ferrite powder has an average particle size of between 0.2 to 0.9 micron.

14. The method of claim 9 wherein the hexagonal ferrite powder has a particle size of between 300-600 nm.

15. The method of claim 9 wherein the hexagonal ferrite powder has a grain size between about five micrometers and one millimeter in diameter.

16. The method of claim 9 wherein the hexagonal ferrite powder has an average surface area of greater than 8 m 2 /g.

17. The method of claim 9 wherein the hexagonal ferrite powder has a surface area of greater than 15 m 2 /g.

18. The method of claim 9 wherein the hexagonal ferrite powder has a surface area of between 8 and about 15 m 2 /g.

19. The method of claim 9 further comprising incorporating the enhanced resonant frequency ferrite material into a magnetic isolator.

20. The method of claim 19 further comprising incorporating the magnetic isolator into a radio-frequency communication system.

Assignees

• Skyworks Solutions Inc

Inventors

• Hill Michael David

Classifications

• C04B35/64 Primary

  Burning or sintering processes (C04B33/32 takes precedence {; powder metallurgy B22F}) · CPC title

• C04B35/624

  Sol-gel processing · CPC title

• C04B2235/3215

  Barium oxides or oxide-forming salts thereof · CPC title

• H01B1/08

  oxides · CPC title

• C01G49/0036

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