Magneto-dielectric material comprising hexaferrite fibers, methods of making, and uses thereof

Patent metadata

Field	Value
Publication number	US-2019013128-A1
Application number	US-201716067181-A
Country	US
Kind code	A1
Filing date	Jan 18, 2017
Priority date	Jan 18, 2016
Publication date	Jan 10, 2019
Grant date	—

Abstract

In an embodiment, a magneto-dielectric material comprises a polymer matrix; a plurality of hexaferrite microfibers; wherein the magneto-dielectric material has a permeability of 2.5 to 7, or 2.5 to 5 in an x-direction parallel to a broad surface of the magneto-dielectric material and a magnetic loss tangent of less than or equal to 0.03; as determined at 1 GHz, or 1 to 2 GHz.

First claim

1 . A magneto-dielectric material comprising:
a polymer matrix; and a plurality of hexaferrite microfibers; wherein the magneto-dielectric material has
a permeability of 2.5 to 7 in an x-direction parallel to a broad surface of the magneto-dielectric material, and
a magnetic loss tangent of less than or equal to 0.03; as determined at 1 GHz.

2 . The magneto-dielectric material of claim 1 , wherein the magneto-dielectric material comprises 10 to 60 vol % of the plurality of hexaferrite microfibers based on the total volume of the magneto-dielectric material.

3 . The magneto-dielectric material of claim 1 , wherein the plurality of hexaferrite microfibers comprises a Z-type hexaferrite, a W-type hexaferrite, a U-type hexaferrite, an X-type hexaferrite, a Y-type hexaferrite, or a combination comprising at least one of the foregoing; or wherein the plurality of hexaferrite microfibers comprises a Z-type hexaferrite.

4 . (canceled)

5 . The magneto-dielectric material of claim 1 , wherein the plurality hexaferrite microfibers comprise a cobalt Z-type hexaferrite having the formula:
(Ba z Sr (3-z) )Co (2+x) Mo x Fe (y-2x) O 41
wherein x is 0.01 to 0.2, y is 20 to 24, and z is 0 to 3.

6 . The magneto-dielectric material of claim 1 , wherein the plurality hexaferrite microfibers have an aspect ratio of greater than or equal to 10.

7 . The magneto-dielectric material of claim 1 , wherein the plurality of hexaferrite microfibers have one or both of
an average diameter of 0.3 to 10 micrometers or an average length of 100 to 5,000 micrometers.

8 . The magneto-dielectric material of claim 1 , wherein the plurality of hexaferrite microfibers comprise a plurality of grains having a grain size of 0.3 to 20 micrometers; wherein 50 to 100% by number of the grains are oriented along an x-y plane of the respective microfiber.

9 . (canceled)

10 . The magneto-dielectric material of claim 1 , wherein the plurality of hexaferrite microfibers are oriented parallel to an x-y plane of the magneto-dielectric material.

11 . (canceled)

12 . The magneto-dielectric material of claim 1 , wherein the permeability of the magneto-dielectric material in the x-direction is 0.75 to 2 times greater than the permeability in the z-direction that is perpendicular to the broad surface.

13 . (canceled)

14 . The magneto-dielectric material of claim 1 , having one or more of
an operating frequency of 1 GHz; a permittivity of less than or equal to 10 as determined at 1 GHz; and a dielectric loss tangent of less than or equal to 0.005 as determined at 1 GHz.

15 . The magneto-dielectric material of claim 1 , further comprising a conductive layer disposed on a surface of the magneto-dielectric material.

16 . The magneto-dielectric material of claim 1 , wherein the polymer matrix comprises a polyolefin, a polyurethane, a silicone, a polyether, poly(phenylene sulfide), or a combination comprising at least one of the foregoing.

17 . The magneto-dielectric material of claim 1 , wherein the polymer matrix comprises a thermoset polybutadiene or polyisoprene or a thermoset polynorbornene.

18 . A method of making the magneto-dielectric material of claim 1 , comprising:
injection molding the polymer matrix and the plurality of hexaferrite microfibers, wherein the polymer matrix comprises a thermoplastic polymer.

19 . A method of making the magneto-dielectric material of claim 1 , comprising:
reaction injection molding a thermosetting polymer precursor composition and the plurality of hexaferrite microfibers.

20 . The method of claim 1 , comprising injection molding or reaction injection molding the polymer matrix and the plurality of hexaferrite microfibers in the presence of a magnetic field.

21 . An article comprising the magneto-dielectric material of claim 1 .

22 . The article of claim 21 , wherein the article is an antenna, a transformer, an anti-electromagnetic interface material, or an inductor.

23 . The article of claim 22 , wherein the article is a microwave device.

24 . The article of claim 21 , comprising the magneto-dielectric material and a dielectric material that comprises 0 to 2 vol % of the plurality of hexaferrite microfibers based on the total volume of the dielectric material.

Assignees

• Rogers Corp

Inventors

• Chen Yajie
• Sprentall Karl Edward
• Sethumadhavan Murali

Classifications

• H01F1/15375

  using polymers · 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

• C08L47/00

  Compositions of homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, at least one having two or more carbon-to-carbon double bonds; Compositions of derivatives of such polymers (C08L45/00 takes precedence; of conjugated diene rubbers C08L9/00 - C08L21/00) · CPC title

• C04B35/26

  based on ferrites · CPC title

• C08G61/08

  of carbocyclic compounds containing one or more carbon-to-carbon double bonds in the ring · CPC title