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EP-4739641-A1 - TEMPERATURE COMPENSATED HIGH DIELECTRIC CONSTANT FERRITES CONTAINING GADOLINIUM AND BISMUTH

EP4739641A1EP 4739641 A1EP4739641 A1EP 4739641A1EP-4739641-A1

Abstract

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 Y 3-y-y-b-2c -Bi x Gd y Ca b+2c Fe 5-a-b-c In a Zr b V c O 12 , wherein 1.0 ≤ x ≤ 1.6, 0.5 ≤ y ≤ 1.0, 0 ≤ a ≤ 0.7, 0.0 ≤ b ≤ 0.7, 0.4 ≤ a + b ≤ 0.7, 0 ≤ c ≤ 0.4, a + c > 0, and x + y + b +2c ≤ 3.

Inventors

  • CRUICKSHANK, DAVID, BOWIE
  • HILL, Michael, David
  • MACFARLANE, Iain, Alexander
  • POLISETTY, SRINIVAS
  • O'DONOVAN, Rickard, Paul

Assignees

  • Allumax TTI, LLC

Dates

Publication Date
20260513
Application Date
20240829

Claims (20)

  1. 1 . A ceramic article for radio frequency applications, the ceramic article being formed of a ceramic material having a chemical formula represented by: Y 3-x-y-b-2c B ixG dyCab+2c F 65-a-b-c I I aZ f bV c012 wherein 1 .0 < x < 1 .6, 0.5 < y < 1 .0, 0 < a < 0.7, 0 < b < 0.7, 0.4 < a + b < 0.7, 0 < c < 0.4, a + c > 0, and x + y + b +2c < 3.
  2. 2. The ceramic article of claim 1 , wherein x + y + b + 2c = 3, such that essentially no Y is present.
  3. 3. The ceramic article of claim 2, wherein 0.6 < y < 1 .0.
  4. 4. The ceramic article of claim 3, wherein 1 .4 < x < 1 .6.
  5. 5. The ceramic article of claim 4, wherein a = 0.
  6. 6. The ceramic article of claim 5, wherein the ceramic material has a dielectric constant greater than 30.
  7. 7. The ceramic article of claim 6, wherein the ceramic material has a Curie temperature of 210 - 260°C.
  8. 8. The ceramic article of claim 1 , wherein the ceramic material has a saturation magnetization of 1350 - 1550 Gauss.
  9. 9. A ceramic article for radio frequency applications, the ceramic article being formed of a ceramic material having a chemical formula represented by Y3-x-y-b-2cBixGdyCab + 2cFe5-a-b-clnaZrbVcOl 2, wherein 1 .0 < x < 1 .6 and 0.5 < y < 1 .0, such that a normalized change (A4KMS) in saturation magnetization (Ms), defined as A4KMS = [(4TIMS at 20°C) - (4JIMS at 120°C)] / (4nMs at 20°C), is about 0.20 - 0.35.
  10. 10. The ceramic article of claim 9, wherein 0.6 < y < 1 .0, 0 < a < 0.7, 0 < b < 0.7, 0.4 < a + b < 0.7, 0 < c < 0.4, a + c > 0, and x + y + b + 2c < 3.
  11. 11. The ceramic article of claim 10, wherein x + y + b + 2c = 3, such that essentially no Y is present.
  12. 12. The ceramic article of claim 11 , wherein 1.4 < x < 1.6.
  13. 13. The ceramic article of claim 10, wherein the ceramic material has a dielectric constant greater than 30.
  14. 14. The ceramic article of claim 10, wherein the ceramic material has a Curie temperature of 210 - 260°C.
  15. 15. The ceramic article of claim 10, wherein the ceramic article is an isolator or a circulator.
  16. 16. The ceramic article of claim 15, wherein the isolator or the circulator is a single piece article having a disc shape without being attached to a dielectric ring.
  17. 17. A radio frequency (RF) circulator comprising a ceramic disk formed of a ceramic material having a chemical formula represented by Y3-x-y-b-2cBixGdyCab+2cFes-a-b- dn a ZrbVcOi2, wherein 1 .0 < x < 1.6 and 0.5 < y < 1 .0, such that a dielectric constant of the ceramic material is greater than 30 and a normalized change (A4TIMS) in saturation magnetization (Ms) of the ceramic material, defined as A4TIMS = [(4KMS at 20°C) - (4TIMS at 120°C)] / (4 Ms at 20°C), is less than about 0.35.
  18. 18. The RF circulator of claim 17, wherein 0.6 < y < 1 .0, 0 < a < 0.7, 0 < b < 0.7, 0.4 < a + b < 0.7, 0 < c < 0.4, a + c > 0, and x + y + b + 2c < 3.
  19. 19. The RF circulator of claim 18, wherein x + y + b + 2c = 3 such that essentially no Y is present.
  20. 20. The RF circulator of claim 19, wherein 1 .4 < x < 1 .6.

Description

TEMPERATURE COMPENSATED HIGH DIELECTRIC CONSTANT FERRITES CONTAINING GADOLINIUM AND BISMUTH David Bowie Cruickshank Michael David Hill lain Alexander Macfarlane Srinivas Polisetty Rickard Paul O’Donovan Field [0001] The present disclosure generally relates to modified garnets having an ultra-high dielectric constant, and applications of such modified garnets. Background [0002] The statements in this section merely provide background information related to the present disclosure and may not constitute prior art. [0003] Various crystalline materials with magnetic properties have been used as components in electronic devices such as cellular phones, biomedical devices, and RFID sensors. Garnets are crystalline materials with ferrimagnetic properties that are particularly useful in RF electronics operating in the lower frequency portions of the microwave region. Many microwave magnetic materials are derivatives of yttrium iron garnet (YIG), a synthetic form of garnet widely used in various telecommunication devices largely because of its favorable magnetic properties, such as narrow linewidth at its ferromagnetic resonance frequency. YIG is generally composed of yttrium, iron, and oxygen, and may be possibly doped with one or more other rare earth metals, such as lanthanides or scandium. Summary [0004] According to one aspect of the present disclosure, a ceramic article for radio frequency applications is formed of a ceramic material having a chemical formula represented by: Y 3-x-y-b-2c B ixG d yCSb+2c F Cs-a-b-c I D aZ f bV c012 wherein 1 .0 < x < 1 .6, 0.5 < y < 1 .0, 0 < a < 0.7, 0 < b < 0.7, 0.4 < a + b < 0.7, 0 < c < 0.4, a + c > 0, and x + y + b + 2c < 3. [0005] According to another aspect of the present disclosure, a ceramic article comprises a ceramic disk formed of a ceramic material having a chemical formula represented by Y3-x-y-b-2cBixGdyCab+2cFe5-a-b-c lnaZrb cOi2, wherein 1 .0 < x < 1 .6 and 0.5 < y < 1 .0, such that a normalized change (A4TIMS) in saturation magnetization (Ms) is about 0.20 - 0.35. This normalized change in saturation magnetization is defined as the following: A4nMs = [(4 MS at 20°C) - (4nMs at 120°C)] I (4 MS at 20°C). [0006] According to yet another aspect of the present disclosure, a radio frequency (RF) circulator comprises a ceramic disk formed of a ceramic material having a chemical formula represented by Bii.o+aY2.o-a-2y Ca2yFe5-y-zVylnzOi2, wherein 1 .0 < x < 1.6 and 0.5 < y < 1.0, such that a dielectric constant of the ceramic material is greater than 30 and a normalized change (A4TCMS) in saturation magnetization (Ms) of the ceramic material is less than about 0.35. [0007] Further areas of applicability will become apparent from the description provided herein. It should be understood that the description and specific examples are intended for purposes of illustration only and are not intended to limit the scope of the present disclosure. Drawings [0008] In order that the disclosure may be well understood, there will now be described various forms thereof, given by way of example, reference being made to the accompanying drawings. [0009] Figure 1 schematically shows how materials having one or more features described herein can be designed, fabricated, and used. [0010] Figure 2 illustrates a magnetic field v. loss chart. [0011] Figure 3 depicts an yttrium-based garnet crystal lattice structure. [0012] Figure 4 is a graph of saturation magnetization as a function of temperature for an yttrium gadolinium iron garnet. [0013] Figure 5A is a graph of normalized change in saturation magnetization (A4KMS) versus Curie temperature of various ferrites including ferrites according to embodiments. [0014] Figure 5B is a graph of normalized change in saturation magnetization ( 4TIMS) versus line width of the various ferrites illustrated in Figure 5A. [0015] Figure 6A is a graph of experimental measurements of a normalized change (A4 MS) in saturation magnetization (Ms) versus temperature of some ferrites according to embodiments. [0016] Figure 6B is an expanded view of the graph shown in FIG. 6A of experimental measurements of the normalized change ( 4TCMS) in saturation magnetization (Ms) versus temperature of the example ferrites according to embodiments. [0017] Figure 6C is a graph of experimental measurements of the normalized change (A4KMS) in saturation magnetization (Ms) of the example ferrites shown in Figure 6A as a function of Curie temperature. [0018] Figure 7A is a graph of experimental measurements of a normalized change ( 4JIMS) in saturation magnetization (Ms) versus temperature of some ferrites according to embodiments. [0019] Figure 7B is an expanded view of the graph shown in FIG. 7A of experimental measurements of the normalized change ( 4TIMS) in saturation magnetization (Ms) versus temperature of the example ferries according to embodiments. [0020] Figure 7C is a graph of experimental measurements of the normalized change ( 4TCMS) in saturation magnetizati