# US 10,483,619 B2 · Modified Ni—Zn ferrites for radiofrequency applications

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- Number: US 10,483,619 B2
- Document ID: US10483619B2
- Status: Granted
- Kind: B2
- Application number: 15/333,569
- Filed: 2016-10-25
- Published: 2017-04-06
- Granted: 2019-11-19
- Earliest claimed: 2010-09-22
- Assignees: Skyworks Solutions, Inc.
- Applicants: Skyworks Solutions, Inc.
- Inventors: Michael David Hill; David Bowie Cruickshank; Kelvin Mitchell Anderson
- Web page: https://patentgrep.com/patent/US10483619B2

## CPC

- H01Q 1/24: with receiving set
- C01G 49/0018: {Mixed oxides or hydroxides, (C01G49/0009 takes precedence)}
- C01G 49/009: {Compounds containing iron, with or without oxygen or hydrogen, and containing two or more other elements}
- C04B 35/265: {Compositions containing one or more ferrites of the group comprising manganese or zinc and one or more ferrites of the group comprising nickel, copper or cobalt}
- C04B 35/6261: {Milling}
- C04B 35/62645: {Thermal treatment of powders or mixtures thereof other than sintering}
- C04B 35/62655: {Drying, e.g. freeze-drying, spray-drying, microwave or supercritical drying}
- C04B 35/645: Pressure sintering
- H01F 1/344: {Ferrites, e.g. having a cubic spinel structure (X2+O)(Y23+O3), e.g. magnetite Fe3O4}
- H01Q 17/004: {using non-directional dissipative particles, e.g. ferrite powders (H01Q17/005 takes precedence; flake-like H01Q17/002)}
- C01P 2002/32: spinel-type (AB2O4)
- C01P 2002/54: one element only
- C01P 2006/32: Thermal properties
- C01P 2006/40: Electric properties
- C01P 2006/42: Magnetic properties
- C04B 2235/3262: Manganese oxides, manganates, rhenium oxides or oxide-forming salts thereof, e.g. MnO
- C04B 2235/3274: Ferrites
- C04B 2235/3275: Cobalt oxides, cobaltates or cobaltites or oxide forming salts thereof, e.g. bismuth cobaltate, zinc cobaltite
- C04B 2235/3279: Nickel oxides, nickalates, or oxide-forming salts thereof
- C04B 2235/3281: Copper oxides, cuprates or oxide-forming salts thereof, e.g. CuO or Cu2O
- C04B 2235/3284: Zinc oxides, zincates, cadmium oxides, cadmiates, mercury oxides, mercurates or oxide forming salts thereof
- C04B 2235/606: Drying
- C04B 2235/656: characterised by specific heating conditions during heat treatment
- C04B 2235/6585: at an oxygen percentage above that of air
- C04B 2235/763: Spinel structure AB2O4
- C04B 2235/81: Materials characterised by the absence of phases other than the main phase, i.e. single phase materials
- C04B 2235/96: Properties of ceramic products, e.g. mechanical properties such as strength, toughness, wear resistance
- H01Q: ANTENNAS, i.e. RADIO AERIALS (radiators or antennas for microwave heating H05B6/72)
- C01G: COMPOUNDS CONTAINING METALS NOT COVERED BY SUBCLASSES C01D OR C01F (metal hydrides {monoborane, diborane or addition complexes thereof} C01B6/00; salts of oxyacids of halogens C01B11/00; peroxides, salts or peroxyacids C01B15/00; thiosulfates, dithionites, polythionates C01B17/64; compounds containing selenium, or tellurium C01B19/00; binary compounds of nitrogen with metals C01B21/06; azides C01B21/08; {compounds containing nitrogen, other non-metals and metal C01B21/082}; metal amides C01B21/092; nitrites C01B21/50; {compounds of noble gases C01B23/0005}; phosphides C01B25/08; salts of oxyacids of phosphorus C01B25/16; carbides C01B32/90; compounds containing silicon C01B33/00; compounds containing boron C01B35/00; compounds having molecular sieve properties but not having base-exchange properties C01B37/00; compounds having molecular sieve and base-exchange properties, e.g. crystalline zeolites, C01B39/00; cyanides C01C3/08; salts of cyanamide C01C3/16; thiocyanates C01C3/20)
- C04B: LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE {(roofing granules E04D7/005)}; CERAMICS (devitrified glass-ceramics C03C10/00); REFRACTORIES; TREATMENT OF NATURAL STONE
- H01F: MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
- C01P: INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS

## Abstract

Embodiments disclosed herein relate to using cobalt (Co) to fine tune the magnetic properties, such as permeability and magnetic loss, of nickel-zinc ferrites to improve the material performance in electronic applications. The method comprises replacing nickel (Ni) with sufficient Co+2 such that the relaxation peak associated with the Co+2 substitution and the relaxation peak associated with the nickel to zinc (Ni/Zn) ratio are into near coincidence. When the relaxation peaks overlap, the material permeability can be substantially maximized and magnetic loss substantially minimized. The resulting materials are useful and provide superior performance particularly for devices operating at the 13.56 MHz ISM band.

## Claims

### Claim 1

A material for radiofrequency applications, the material comprising:
a single-phase modified Ni—Zn ferrite formed from a base Ni—Zn ferrite, the single-phase modified Ni—Zn ferrite including elements Ni, Zn, Co, Fe, and O with a composition Ni0.5725Co0.0275Zn0.4Fe2O4, and having a spinel crystal structure and magnetic Q of greater than 100.

### Claim 2 (depends on 1)

The material of claim 1 wherein the single-phase modified Ni—Zn ferrite has a permeability of 54 at 1 MHz.

### Claim 3 (depends on 1)

The material of claim 1 wherein the base Ni—Zn ferrite has the formula Ni0.5Zn0.5Fe2O4.

### Claim 4 (depends on 1)

The material of claim 1 wherein the single-phase modified Ni—Zn ferrite is sintered at a temperature range of 1100° C.-1400° C. in air or in oxygen.

### Claim 5 (depends on 1)

A radiofrequency device selected from the group consisting of radio-frequency identification tags, biomedical sensors, and radiofrequency antennas including the radiofrequency material of claim 1.

### Claim 6 (depends on 5)

The radiofrequency device of claim 5 wherein the radiofrequency device is a biomedical sensor.

### Claim 7 (depends on 5)

The radiofrequency device of claim 5 wherein the radiofrequency device is a radiofrequency identification tag.

### Claim 8

A radiofrequency antenna, the antenna being formed from a nickel zinc ferrite comprising:
a single-phase modified Ni—Zn ferrite, the single-phase modified Ni—Zn ferrite including elements Ni, Zn, Co, Fe, and O with a composition Ni0.5725Co0.0275Zn0.4Fe2O4, having a spinel crystal structure, and having a magnetic Q of greater than 100.

### Claim 9 (depends on 8)

The radiofrequency antenna of claim 8 wherein the single-phase modified Ni—Zn ferrite is sintered at a temperature range of 1100° C.-1400° C. in air or in oxygen.

### Claim 10 (depends on 8)

The radiofrequency antenna of claim 8 wherein the single-phase modified Ni—Zn ferrite has a permeability of 54 at 1 MHz.

### Claim 11

A method of forming an improved nickel zinc ferrite for radiofrequency applications, the method comprising:
blending raw oxides having nickel, iron, cobalt, and zinc, and;
calcining the blended material;
milling the calcined material; and
spray drying the material with a binder to form a single-phase modified Ni—Zn ferrite powder including elements Ni, Zn, Co, Fe, and O having a composition Ni0.5725Co0.0275Zn0.4Fe2O4, and having a spinel crystal structure a magnetic Q of greater than 100.

### Claim 12 (depends on 11)

The method of claim 11 wherein the calcining is performed at a temperature range of 900° C.-1200° C.

### Claim 13 (depends on 11)

The method of claim 11 further comprising:
pressing the single-phase modified Ni—Zn ferrite powder into a form of a part; and
sintering the part to form a sintered part.

### Claim 14 (depends on 13)

The method of claim 13 wherein the sintering is performed at a temperature range of 1100° C.-1400° C. in air or in oxygen.

### Claim 15 (depends on 13)

The method of claim 13 wherein the sintered part is a radiofrequency antenna.

### Claim 16 (depends on 11)

The method of claim 11, wherein the single-phase modified Ni—Zn ferrite has a permeability of 54 at 1 MHz.

### Claim 17 (depends on 11)

The method of claim 11 wherein the blending is shear mixing.

### Claim 18 (depends on 11)

The method of claim 11 wherein the blending is vibratory mill blending.

### Claim 19 (depends on 11)

The method of claim 11 wherein the milling includes milling the calcined material to a particle size between 1 to 10 microns.

### Claim 20 (depends on 11)

The method of claim 11 wherein the pressing is isostatic pressing.