Radiofrequency and other electronic devices formed from enhanced resonant frequency hexaferrite materials
Radiofrequency and other electronic devices can be formed from textured hexaferrite materials, such as Z-phase barium cobalt ferrite Ba 3 Co 2 Fe 24 O 41 (Co 2 Z) 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.
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.