Z-type hexaferrite having a nanocrystalline structure

Patent metadata

Field	Value
Publication number	US-11691892-B2
Application number	US-202117166352-A
Country	US
Kind code	B2
Filing date	Feb 3, 2021
Priority date	Feb 21, 2020
Publication date	Jul 4, 2023
Grant date	Jul 4, 2023

Abstract

In an aspect, a Co2Z ferrite has the formula: (Ba1-xSrx)3Co2+yMyFe24-2y-zO41. M is at least one of Mo, Ir, or Ru. The variable x can be 0 to 0.8, or 0.1 to 0.8. The variable y can be 0 to 0.8, or 0.01 to 0.8. The variable z can be −2 to 2. The Co2Z ferrite can have an average grain size of 5 to 100 nanometers, or 30 to 80, or 10 to 40 nanometers as measured using at least one of transmission electron microscopy, field emission scanning electron microscopy, or x-ray diffraction.

First claim

What is claimed is:

1. A Co 2 Z ferrite having the formula:
(Ba 1-x Sr x ) 3 Co 2+y M y Fe 24-2y-z O 41
wherein M is at least one of Mo, Ir, or Ru; x is 0 to 0.8; y is 0 to 0.8; and z is −2 to 2; and
wherein the Co 2 Z ferrite has an average grain size of 5 to 100 nanometers as measured using at least one of transmission electron microscopy, field emission scanning electron microscopy, or x-ray diffraction; and
wherein
y is 0.01 to 0.8, or
x is 0.1 to 0.8, or
M is present and is at least one of Ru or Mo, or
the Co 2 Z ferrite has a median D50 particle size by volume of 1 to 30 micrometers as measured using Horiba LA-910 laser light scattering PSD analyzer or as determined in accordance with ASTM D4464-15, or
a combination thereof.

2. The Co 2 Z ferrite of claim 1 , wherein y is 0.01 to 0.8.

3. The Co 2 Z ferrite of claim 1 , wherein x is 0.1 to 0.8.

4. The Co 2 Z ferrite of claim 1 , M is at least one of Ru or Mo.

5. The Co 2 Z ferrite of claim 1 , wherein the Co 2 Z ferrite has a median D50 particle size by volume of 1 to 30 micrometers as measured using Horiba LA-910 laser light scattering PSD analyzer or as determined in accordance with ASTM D4464-15.

6. A composite comprising a polymer and the ferrite composition of claim 1 .

7. The composite of claim 6 , wherein the composite has a permeability of greater than or equal to 1.5 at a frequency of 0.5 to 5 gigahertz.

8. The composite of claim 6 , wherein the composite has a permittivity of 6 to 15 at a frequency of 0.5 to 5 gigahertz.

9. The composite of claim 6 , wherein the composite has a magnetic loss tangent tan δ μ of less than or equal to 0.04 at a frequency of 0.5 to 5 gigahertz.

10. The composite of claim 6 , wherein the composite has a dielectric loss tangent tan δ ε of less than or equal to 0.04 at a frequency of 0.5 to 5 gigahertz.

11. The composite of claim 6 , wherein the polymer comprises at least one of polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), polyethylene (PE), high density polyethylene (HDPE), low density polyethylene (LDPE), polymethylmethacrylate (PMMA), polyether ether ketone (PEEK), or polyethersulfone (PES).

12. A composite comprising:
a polymer comprising at least one of polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), polyethylene (PE), high density polyethylene (HDPE), low density polyethylene (LDPE), polymethylmethacrylate (PMMA), polyether ether ketone (PEEK), or polyethersulfone (PES); and
a ferrite composition of having the formula:
(Ba 1-x Sr x ) 3 Co 2+y M y Fe 24-2y-z O 41

wherein M is at least one of Mo or Ru; x is 0.1 to 0.8; y is 0.01 to 0.8; and z is −2 to 2; and
wherein the Co 2 Z ferrite has an average grain size of 5 to 100 nanometers as measured using at least one of transmission electron microscopy, field emission scanning electron microscopy, or x-ray diffraction.

13. An article comprising the ferrite composition of claim 1 .

14. The article of claim 13 , wherein the article is an antenna, a filter, an inductor, a circulator, or an EMI suppressor.

15. A method of making a Co 2 Z ferrite comprising:
milling ferrite precursor compounds comprising Fe, Co, Ba, and M, wherein M is at least one of Mo, Ir, or Ru to form an oxide mixture;
calcining the oxide mixture in an oxygen or air atmosphere to form a calcined ferrite;
high energy milling the calcined ferrite at an energy sufficient to form the Co 2 Z ferrite having a nanocrystalline structure having an average grain size of 5 to 100 nm as measured using at least one of transmission electron microscopy, field emission scanning electron microscopy, or x-ray diffraction.

16. The method of claim 15 , wherein the high energy milling comprises milling in at least one of a high energy ball mill, a vibrating mill, a cryogenic grinder, or an attrition mill.

17. The method of claim 15 , wherein the high energy milling comprises milling in a high energy ball mill; wherein at least one of:
a ratio of the calcined ferrite to the balls is greater than or equal to 15:1;
an average diameter of the balls is 5 to 20 millimeters; or
the balls comprise steel balls.

18. The method of claim 15 , wherein the high energy milling occurs for greater than or equal to 4 hours; or at a mixing speed of greater than or equal to 300 revolutions per minute.

19. The method of claim 15 , further comprising post-annealing the Co 2 Z ferrite in an oxygen or air atmosphere after the high energy milling; optionally at an annealing temperature of 900 to 1,300° C. for an annealing time of 1 to 20 hours; or wherein the calcining the oxide mixture occurs at a calcining temperature of 1,000 to 1,300° C. for a calcining time of 1 to 20 hours.

20. The method of claim 15 , further comprising forming a composite comprising the Co 2 Z ferrite and a polymer.

Assignees

• Rogers Corp

Inventors

• Chen Yajie
• Zhang Li
• Williams Shawn

Classifications

• C01P2004/64

  Nanometer sized, i.e. from 1-100 nanometer · CPC title

• C01P2004/04

  obtained by TEM, STEM, STM or AFM · CPC title

• C08K2201/01

  Magnetic additives · CPC title

• H01F1/348 Primary

  Hexaferrites with decreased hardness or anisotropy, i.e. with increased permeability in the microwave (GHz) range, e.g. having a hexagonal crystallographic structure · CPC title

• C08K3/22

  of metals · CPC title