High saturation magnetization and high dielectric constant ferrites
The disclosed technology relates to a ceramic composition and an article formed therefrom. A ceramic article for radio frequency applications is formed of a ceramic material having a chemical formula represented by: Bi 1.0+a Y 2.0−a−x−2y Ca x+2y Fe 5−x−y M IV x V y O 12 or Bi 1.0+a Y 2.0−a−2y Ca 2y Fe 5−y−z V y In z O 12 . The ceramic material has a composition such that a normalized change in saturation magnetization (Δ4πMs), defined as Δ4πMs=[(4πMs at 20° C.)−(4πMs at 120° C.)]/(4πMs at 20° C.), is less than about 0.35.
1. A ceramic article for radio frequency applications, the ceramic article being formed of a ceramic material having a chemical formula represented by:
Bi 1.0+a Y 2.0−a−x−2y Ca x+2y Fe 5−x−y M IV x V y O 12 , and M IV =Zr, Sn or Ti, 0<x<0.5, 0≤y≤0.25, and 0≤ a≤0.5.
2. The ceramic article of claim 1 , wherein 0.3≤a≤0.5.
3. The ceramic article of claim 2 , wherein a is about 0.4.
4. The ceramic article of claim 1 , wherein 0.3≤x<0.5.
5. The ceramic article of claim 1 , wherein y>0.
6. The ceramic article of claim 5 , wherein 0.14≤y≤0.25.
7. The ceramic article of claim 1 , wherein the ceramic material consists essentially of Bi, Y, Ca, Fe, M IV , V and O.
8. A ceramic article for radio frequency applications, the ceramic article being formed of a ceramic material having a chemical formula represented by Bi 1.0+a Y 2.0−a−x−2y Ca x+2y Fe 5−x−y M IV x V y O 12 , M IV being Zr, Sn or Ti, Sn or Ti, 0<x<0.5, 0≤y≤0.25, and 0≤a≤0.5, and the ceramic material having a composition such that a normalized change (Δ4πMs) in saturation magnetization (Ms), defined as Δ4πMs=[(4πMs at 20° C.)−(4πMs at 120° C.)]/(4πMs at 20° C.), is less than about 0.35.
9. The ceramic article of claim 8 , wherein the ceramic material has a dielectric constant greater than 28.
10. The ceramic article of claim 8 , wherein the ceramic material has a saturation magnetization of 1550-1850 Gauss.
11. The ceramic article of claim 8 , wherein the ceramic material has a dielectric loss tangent less than 0.001.
12. The ceramic article of claim 8 , wherein the ceramic material has a 3 dB linewidth of less than 50 Oe.
13. The ceramic article of claim 8 , wherein the ceramic material has a Curie Temperature between 200° C. and 300° C.
14. The ceramic article of claim 8 , wherein the ceramic article is an isolator or a circulator.
15. The ceramic article of claim 14 , wherein the isolator or the circulator is a single piece article having a disc shape without being attached to a dielectric ring.
16. A radio frequency (RF) circulator comprising:
a ceramic disk formed of a ceramic material having a chemical formula represented by Bi 1.0+a Y 2.0−a−x−2y Ca x+2y Fe 5−x−y M IV y O 12 , M IV being Zr, Sn or Ti, 0<x<0.5, 0≤y≤0.25, and 0≤a≤0.5, and the ceramic material has a composition such that a normalized change (Δ4πMs) in saturation magnetization (Ms), defined as Δ4πMs=[(4πMs at 20° C.)−(4πMs at 120° C.)]/(4πMs at 20° C.), is less than about 0.35.
17. The RF circulator of claim 16 , wherein:
0<x<5,
0≤y≤0.25, and
0≤a≤0.5.
18. The RF circulator of claim 16 , wherein the circulator is a single piece article having a disc shape without being attached to a dielectric ring.
19. The RF circulator of claim 16 , wherein the ceramic material has a dielectric constant greater than 28.
20. The RF circulator of claim 16 , wherein the ceramic material has a saturation magnetization of 1550-1850 Gauss.