18H hexagonal ferrite and manufacturing method and application thereof

Abstract

A ferrite composition having the formula BaxNi2-yCuyTi3FezO31, where 4.5 < = x < = 5.5, 0 lt; yt; Yt; 2 or 0.05 < = y < = 1.5, and 11 < = z < = 13.

Description

Cross - Reference to Related Applications This application claims the benefit of U.S. Provisional Application Serial No. 63 / 424,616, filed on November 11, 2022, which is incorporated herein by reference in its entirety. BACKGROUND OF THE DISCLOSURE The present disclosure relates to 18H hexagonal ferrite compositions such as 18H hexagonal ferrite compositions having high - frequency permeability, composite materials containing the 18H hexagonal ferrite compositions, methods for manufacturing the same, and uses thereof. There is a need to improve performance and miniaturization to meet the growing demands of devices used in ultra - high - frequency, L - band, and S - band applications, which are of interest in a variety of commercial and defense - related industries. As important components in radar and modern wireless communication systems, antenna elements with compact sizes are being continuously developed. However, developing ferrite materials for such high - frequency applications is challenging because most ferrite materials exhibit high magnetic losses at high frequencies. The methods for manufacturing ferrite materials can affect the crystal structure of the materials, thereby improving performance. Therefore, there is still a need for ferrite materials having low magnetic losses, high magnetic permeability, and low dielectric constant and dielectric loss in the gigahertz range, and methods for manufacturing such ferrite materials. SUMMARY OF THE INVENTION The ferrite composition has the formula Ba x Ni 2-y Cu y Ti3Fe z O 31 , where 4.5 ≤ x ≤ 5.5, 0 < y < 2 or 0.05 ≤ y ≤ 1.5, and 11 ≤ z ≤ 13. The method for manufacturing a ferrite composition includes calcining the blended metal source compounds for the ferrite composition; reducing the particle size of the calcined source compounds to obtain particles having an average particle size of 0.5 micrometers to 100 micrometers or 0.5 micrometers to 10 micrometers; granulating a mixture of the particles and a binder to obtain granulated bodies; pressing the granulated bodies into green compacts; and sintering the green compacts to form the ferrite composition. The composite material includes a polymer matrix and a ferrite composition. Articles containing the ferrite composition or the composite material are also described, and the articles include antennas, inductors, transformers, or electromagnetic interference shielding materials. BRIEF DESCRIPTION OF THE DRAWINGS The following drawings are provided to illustrate exemplary embodiments of the present disclosure. The drawings are for illustrative purposes only and are not intended to limit the devices manufactured in accordance with the present disclosure to the materials, conditions, or process parameters set forth herein. Figure 1 There is presented 18H hexagonal ferrite Ba5Ti3Ni2-y Cu y Fe 12 O 31 (where 0 < y < 2) Schematic diagram of half of the 18 - layer stacking sequence of the unit cell; Figure 2 Is a graph of magnetization (emu / g) versus temperature (°C) for Examples 1 - 8; Figure 3 Is a graph of the real - part magnetic permeability μ' versus frequency (f) (gigahertz (GHz)) for Examples 1 - 8; Figure 4 Is a graph of the imaginary - part magnetic permeability μ” versus frequency (GHz) for Examples 1 - 8; Figure 5 Is a graph showing the real - part magnetic permeability μ' and the imaginary - part magnetic permeability μ” of the magnetic spectrum of the composite material of Example 9 versus frequency (f) (GHz); and Figure 6 Is a graph showing the real - part dielectric constant ε' and the imaginary - part dielectric constant ε” of the magnetic spectrum of the composite material of Example 9 versus frequency (f) (GHz). Detailed Description of the Invention It has been found that an 18H - type ferrite composition containing nickel and copper has a low magnetic loss tangent and a high magnetic permeability at high frequencies, while also exhibiting a low dielectric loss tangent and a high dielectric constant. It has also been found that the properties of the ferrite composition, such as magnetic permeability, saturation magnetization, coercivity, Curie temperature, cut - off frequency (resonance frequency), or combinations thereof, can be adjusted by changing the copper content (e.g., the molar ratio of copper to nickel) in the ferrite composition. Advantageously, the preparation of the 18H - type ferrite composition is cost - effective because it does not require expensive elements such as rare - earth or noble - metal elements. When mixed with a polymer, the ferrite composition provides a composite material having low magnetic loss, high magnetic permeability, low dielectric constant, and low dielectric loss. The ferrite compositions and composite materials described herein can be used in applications such as antenna substrates, inductor cores, and electromagnetic interference (EMI) suppressors in a wide frequency range (0.5 gigahertz (GHz) to 10 GHz). Figure 1 Presents the 18H hexagonal ferrite Ba5Ti3Ni 2-y Cu y Fe 12 O 31 (where 0 < y < 2) Schematic diagram of half of the 18 - layer stacking sequence of the unit cell, which shows a half - Y block of 3 layers, a hexagonal barium titanate (HBT) of 3 layers, and a half - Y block of 3 layers. The actual distribution of the interstitial cations can be different to provide a magnetic coupling path along the c - axis. The HBT layer can also contain iron ions; copper ions; nickel ions; or combinations thereof. The ferrite composition has the formula Bax Ni 2-y Cu y Ti3Fe z O 31 , where 4.5 ≤ x ≤ 5.5, 0 < y < 2 or 0.05 ≤ y ≤ 1.5, and 11 ≤ z ≤ 13. The ferrite composition may have a 18H structure. The ferrite composition may have in-plane (c basal plane) easy magnetization (also known as planar anisotropy). The ferrite composition may be a single-crystal or polycrystalline ferrite composition. The Curie temperature of the ferrite composition may be greater than or equal to 200 °C, greater than or equal to 210 °C, greater than or equal to 220 °C, greater than or equal to 230 °C, greater than or equal to 240 °C, or greater than or equal to 250 °C. The Curie temperature of the ferrite composition may be less than or equal to 300 °C. The Curie temperature of an 18H-type ferrite composition that does not contain nickel and copper may be less than 180 °C. The coercivity of the ferrite composition may be less than 50 Oersteds (Oe) (3.98 kiloamperes per meter (kA / m)), less than 30 Oe (2.39 kA / m), less than 15 Oe (1.19 kA / m), less than 5 Oe (0.40 kA / m), less than 4 Oe (0.32 kA / m), less than 3 Oe (0.24 kA / m), less than 2 Oe (0.16 kA / m), or less than 1 Oe (0.08 kA / m). The coercivity of the ferrite composition may be greater than 0 Oe (0 kA / m), greater than 0.01 Oe (0.80 amperes per meter (A / m)), or greater than 0.1 Oe (7.96 A / m). The coercivity of an 18H-type ferrite composition that does not contain nickel and copper may be greater than 50 Oe (3.98 kA / m). The grain size of the ferrite composition can be selected to provide a ferrite composition having magnetodielectric properties suitable for a given application. The grain size can be controlled by controlling ferrite synthesis conditions such as temperature, heating time, and heating rate or cooling rate. The average grain size of the ferrite composition can be from 1 μm to 100 μm, or from 5 μm to 50 μm. The average grain size can be determined, for example, by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), or a combination thereof. The ferrite composition may have the following formula Ba x Ni 2-y Cu y Ti3Fe z O 31 , where 5.0 ≤ x ≤ 5.1, 0.05 ≤ y ≤ 1.5, and 11.7 ≤ z ≤ 12.0. In one embodiment, the ferrite composition may have the formula Ba5.1 Ni 1.8 Cu 0.2 Ti3Fe 11.7 O 31 、Ba 5.1 Ni 1.6 Cu 0.4 Ti3Fe 11.7 O 31 、Ba 5.1 Ni 1.4 Cu 0.6 Ti3Fe 11.7 O 31 、Ba 5.1 Ni1Cu 1.0 Ti3Fe 11.7 O 31 、Ba 5.1 Ni 0.8 Cu 1.2 Ti3Fe 11.7 O 31 、Ba 5.1 Ni 1.7 Cu 1.3 Ti3Fe 11.7 O 31 、Ba 5.1 Ni 1.6 Cu 1.4 Ti3Fe 11.7 O 31 、 or Ba 5.1 Ni 0.5 Cu 1.5 Ti3Fe 11.7 O 31 。 The ferrite composition may have a permeability (μ) of 1.5 to 2 at a frequency of 1 GHz to 9 GHz; a magnetic loss tangent (tanδ μ ) of less than 0.05 at a frequency of 1 GHz to 9 GHz; a dielectric constant (ε) of 10 to 15 at a frequency of 1 GHz to 9 GHz; a dielectric loss tangent (tanδ ε ) of less than 0.004 at a frequency of 1 GHz to 3 GHz; a cut-off frequency (resonance frequency, f r ) greater than 10 GHz; or a combination of the foregoing. In one embodiment, the ferrite composition has both a permeability (μ) of 1.5 to 2 at a frequency of 1 GHz to 9 GHz and a magnetic loss tangent (tanδ μ ) of less than 0.05 at the same frequency. Hexagonal ferrite particles can be manufactured by any suitable method, such as ceramic processes, sol-gel processes, hydrothermal synthesis, co-precipitation methods, or thermal plasma sintering. Examples of methods for manufacturing ferrite compositions include one-step sintered ceramic processes and wet chemical processes. In one embodiment, a method for manufacturing a ferrite composition can include: calcining a blended metal source compound for the desired ferrite composition; reducing the particle size of the calcined source compound to obtain particles having an average particle size of from 0.5 μm to 100 μm or from 0.5 μm to 10 μm; granulating a mixture of the particles and a binder to obtain a granulated body; pressing the granulated body into a green body; and sintering the green body to form a ferrite composition. Metal source compounds are compounds required for synthesizing ferrites. Metal source compounds can be selected based on factors such as cost and availability. Exemplary source compounds for a given metal include oxides, carbonates, acetates, nitrates, sulfates, or chlorides of the metal. Exemplary precursors include barium carbonate (e.g., BaCO3), iron oxides (e.g., α-Fe2O3, Fe(NO3)3·9H2O, FeCl3·6H2O, or Fe2(SO4)3·H2O), nickel oxide (e.g., NiO), titanium oxide (e.g., TiO2), and copper oxide (e.g., CuO). Metal source compounds can be combined in amounts that achieve the desired metal stoichiometry. In one embodiment, the desired metal stoichiometry can be non-stoichiometric, such as iron-deficient (e.g., z in the formula Ba x Ni 2- y Cu y Ti3Fe z O 31 can be 11.7 instead of 12). Calcining the blended metal source compound can be carried out at a suitable temperature for a certain duration to synthesize the desired ferrite and achieve the desired grain size. For example, the temperature can be from 800 °C to 1,300 °C, or from 900 °C to 1,200 °C, or from 1,000 °C to 1,200 °C. The duration can be, for example, from 0.5 hour to 200 hours, or from 1 hour to 15 hours. The calcination is carried out in an atmosphere of air, nitrogen, oxygen, or a combination thereof. The heating rate or cooling rate for calcination in the furnace can also be selected to obtain the desired ferrite, grain size, or structural morphology. For example, the heating rate or cooling rate can be from 2 °C / minute to 3 °C / minute. The particle size of the calcined blend can be reduced by any suitable method. Examples of methods for reducing the particle size include crushing, grinding, milling, mechanical milling, and combinations thereof. Examples of apparatuses for reducing the particle size include media mills, ball mills, two-roll mills, three-roll mills, bead mills, jet mills, and cryogenic grinders. After reducing the particle size, the particles can be subjected to a sizing step such as sieving to alter the particle size distribution. Granulation of the mixture of ferrite particles and binder can be carried out by any suitable method, such as by spray drying granulation method or oscillating extrusion granulation method. For example, a slurry of ferrite particles, binder, and various additives as needed can be dispersed in a solvent such as water, and then the slurry can be spray dried using, for example, a spray dryer to produce particulate matter. In one embodiment, ferrite particles, binder, and various additives as needed can be mixed and granulated using a stirring granulator to produce granular powder. Then the granular powder can be extruded and granulated using an oscillating granulator to produce particulate matter. The binder is selected to be removable from the green body, optionally by heating for dissolution in a solvent. Examples of binders include polyvinylpyrrolidone, poly(vinyl alcohol), polyvinyl butyral, polyacrylamide, poly(acrylic acid), polyethylene glycol, poly(ethylene oxide), cellulose acetate, starch, poly(propylene carbonate), poly(vinyl acetate), and combinations thereof. In one embodiment, the binder is polyvinyl alcohol, polyvinyl butyral, or a combination thereof. In one embodiment, based on the total weight of the mixture, the particulate matter can be formed from a mixture comprising ferrite particles and 0.5 wt% to 5 wt% of polyvinyl alcohol. The particle size of the particulate matter can be, for example, 50 μm to 300 μm. The granulated ferrite composition is formed into a predetermined shape by, for example, injection molding, calendering lamination, extrusion molding, or compression molding methods such as single pressing method, double pressing method, floating die method, or withdrawal method to obtain a green body. A press is appropriately selected according to the selected size, shape, and quantity of the green body, such as a mechanical press, a hydraulic press, or a servo press. The molding pressure for forming the green body can be 0.3 metric tons per square centimeter (MT / cm 2 ) to 3 MT / cm 2 , or 0.5 MT / cm 2 to 2 MT / cm 2 . The green body can then be sintered in a suitable atmosphere to form a ferrite composition. The sintering can occur at a sintering temperature of 800 °C to 1,300 °C, 900 °C to 1,250 °C, or 1,000 °C to 1,200 °C. The sintering can be carried out for a sintering time of 1 hour to 20 hours, or 2.55 hours to 12 hours. The atmosphere can be air, nitrogen, oxygen, or a combination thereof. The sintering can be carried out at a heating rate of 1 °C / minute to 5 °C / minute, a cooling rate of 1 °C / minute to 5 °C / minute, or a combination thereof. The ferrite can be a bulk ceramic, or it can be present in a composite material such as a composite material comprising ferrite particles and a polymer. The composite material can comprise a ferrite composition and a polymer matrix. Based on the total volume of the composite material, the composite material can comprise 5 volume percent (vol%) to 95 vol%, 10 vol% to 90 vol%, 20 vol% to 80 vol%, or 30 vol% to 70 vol% of the ferrite composition. Based on the total volume of the composite material, the composite material can comprise 5 vol% to 95 vol%, 10 vol% to 90 vol%, 20 vol% to 80 vol%, or 30 vol% to 70 vol% of the polymer. The particle size of the ferrite composition present in the composite material is 0.5 μm to 100 μm, 0.5 μm to 30 μm, or 1 μm to 10 μm. The particle size can be determined using a Horiba LA-910 laser light scattering PSD analyzer or a similar instrument, or as determined in accordance with ASTM D4464-15. The reported particle size is the median D50 particle size by volume. Ferrite composition particles of suitable size can be obtained by any suitable method. For example, any suitable ceramic process or chemical process can be used to synthesize ferrite composition particles of the desired size. In one embodiment, the ferrite composition particles can be obtained by crushing and grinding the sintered green body obtained by the methods described herein. The polymer matrix can include a thermosetting polymer or a thermoplastic polymer. As used herein, the term "thermoplastic" refers to a material that is plastic or deformable, melts into a liquid when heated, and freezes into a brittle glassy state when sufficiently cooled. Examples of thermoplastic polymers that can be used include cycloolefin polymers (including polynorbornene and copolymers containing norbornenyl units, e.g., copolymers of cyclic polymers such as norbornene and acyclic olefins such as ethylene or propylene), fluoropolymers (e.g., polyvinyl fluoride, polyvinylidene fluoride, fluorinated ethylene-propylene, polytetrafluoroethylene, poly(ethylene-tetrafluoroethylene), or perfluoroalkoxy), polyacetals (e.g., polyoxymethylene and polyformaldehyde), polyacrylic (C 1-6 alkyl) esters, polyacrylamides (including unsubstituted and mono-N- or di-N-(C 1-8(alkyl)acrylamide), polyacrylonitrile, polyamide (e.g., aliphatic polyamide, polyphthalamide or polyaramide), polyamideimide, polyanhydride, polyarylene ether (e.g., polyphenylene ether), polyarylene ether ketone (e.g., polyetheretherketone and polyetherketoneketone), polyarylene ketone, polyarylene sulfide (e.g., polyphenylene sulfide), polyarylene sulfone (e.g., polyethersulfone or polysulfone), polybenzothiazole, polybenz oxazole, polybenzimidazole, polycarbonate (including homopolycarbonate or polycarbonate copolymer, e.g., polycarbonate - siloxane, polycarbonate - ester or polycarbonate - ester - siloxane), polyester (e.g., polyethylene terephthalate, polybutylene terephthalate, polyarylate or polyester copolymer such as polyester - ether), polyetherimide (e.g., copolymer such as polyetherimide - siloxane copolymer), polyimide (e.g., copolymer such as polyimide - siloxane copolymer), poly(C 1-6 (alkyl)methacrylate, polyalkylacrylamide (e.g., unsubstituted and mono - N - or di - N - (C 1-8 (alkyl)acrylamide), polyolefin (e.g., polyethylene, such as high - density polyethylene, low - density polyethylene and linear low - density polyethylene, polypropylene, and its halogenated derivatives (e.g., polytetrafluoroethylene), and its copolymers (e.g., ethylene - α - olefin copolymer)), poly oxadiazole, polyoxymethylene, polyphthalide, polysilazane, polysiloxane (silicone), polystyrene (e.g., copolymer such as acrylonitrile - butadiene - styrene or methyl methacrylate - butadiene - styrene), polysulfide, polysulfonamide, polysulfonate, polysulfone, polythioester, polytriazine, polyurea, polyurethane, vinyl polymer (e.g., polyvinyl alcohol, polyvinyl ester, polyvinyl ether, polyhaloethylene (e.g., polyvinyl chloride), polyvinyl ketone, polyvinyl cyanide, or polyvinyl sulfide), paraffin, or a combination thereof. Thermosetting polymers are derived from thermosetting monomers or prepolymers (resins) that can be irreversibly hardened and rendered insoluble upon polymerization or curing, and the polymerization or curing can be initiated by heat or exposure to radiation (e.g., ultraviolet light, visible light, infrared light, or electron beam (e - beam) radiation). Thermosetting polymers include alkyd resins, bismaleimide polymers, bismaleimide triazine polymers, cyanate ester polymers, benzocyclobutene polymers, benz azine polymers, diallyl phthalate polymers, epoxy resins, hydroxymethyl furan polymers, melamine - formaldehyde polymers, phenolic resins (including phenol - formaldehyde polymers, e.g., novolac and resole), benz azines, polydienes such as polybutadiene (including its homopolymers and copolymers, such as poly(butadiene-isoprene)), polyisocyanates, polyureas, polyurethanes, triallyl cyanurate polymers, triallyl isocyanurate polymers, certain silicones, or polymerizable prepolymers (e.g., prepolymers having ethylenic unsaturation, such as unsaturated polyesters, polyimides). The prepolymers can be polymerized, copolymerized, or crosslinked, for example, with reactive monomers such as: styrene, α-methylstyrene, vinyltoluene, chlorostyrene, acrylic acid, (meth)acrylic acid, acrylic (C 1-6 alkyl) esters, methacrylic (C 1-6 alkyl) esters, acrylonitrile, vinyl acetate, allyl acetate, triallyl cyanurate, triallyl isocyanurate, or acrylamide. The polymers can include fluoropolymers (e.g., polyvinylidene fluoride or polytetrafluoroethylene), polyolefins (e.g., polyethylene, high-density polyethylene, low-density polyethylene), poly(arylene ether ketones) (e.g., polyetheretherketone), poly(alkyl meth)acrylates (e.g., polymethyl methacrylate), poly(ethersulfone), or combinations thereof. The composite material can contain additional additives, such as dielectric fillers or flame retardants, provided that the additives are less than 5 volume % of the total volume of the composite material. Particle dielectric fillers can be used to adjust the dielectric constant, dissipation factor, coefficient of thermal expansion, and other properties of the composite material. Exemplary dielectric fillers include titanium dioxide (rutile and anatase), barium titanate, strontium titanate, silica (including fused amorphous silica), corundum, wollastonite, Ba2Ti9O 20 , solid glass spheres, synthetic glass or ceramic hollow spheres, quartz, boron nitride, aluminum nitride, silicon carbide, beryllium oxide, alumina, aluminum trihydroxide, magnesia, mica, talc, nanoclay, magnesium hydroxide, or combinations thereof.

[0041] The flame retardants can be halogenated or non-halogenated. One exemplary inorganic flame retardant is a metal hydrate, such as a hydrate of a metal such as Mg, Ca, Al, Fe, Zn, Ba, Cu, Ni, or combinations thereof. In one embodiment, the hydrate can include: aluminum hydroxide, magnesium hydroxide, calcium hydroxide, iron hydroxide, zinc hydroxide, copper hydroxide, or nickel hydroxide; or a hydrate of calcium aluminate, gypsum dihydrate, zinc borate, or barium metaborate. Alternatively or in addition to the inorganic flame retardants, organic flame retardants can be used. Examples of inorganic flame retardants include, for example, melamine cyanurate / ester, fine particle size melamine polyphosphate / ester, various other phosphorus-containing compounds (e.g., aromatic hypophosphite / ester, secondary phosphite / ester, phosphite / ester, and phosphate / ester), certain polyhedral oligomeric silsesquioxanes, siloxanes, or halogenated compounds (e.g., hexachloronorbornene tetrahydrophthalic acid (HET acid), tetrabromophthalic acid, or dibromoneopentyl glycol).

[0042] The composite material can have an operating frequency of 0.5 GHz to 10 GHz.

[0043] The composite material can have a magnetic loss tangent (tanδ μ ) less than 0.08 at a frequency of 1 GHz to 10 GHz. A magnetic material with such low magnetic loss can be advantageously used in high-frequency applications such as antenna applications.

[0044] The composite material can have a magnetic permeability (μ) greater than or equal to 1.2 at a frequency of 1 GHz to 10 GHz.

[0045] The composite material can have a dielectric constant (ε) of 5 to 10 at a frequency of 1 GHz to 12 GHz.

[0046] The composite material can have a dielectric loss tangent (tanδ ε ) less than 0.005 at a frequency of 1 GHz to 12 GHz.

[0047] A method of manufacturing a composite material includes combining a polymer, a ferrite composition, an optional solvent, and any additives to form a composition. The polymer can be melted before or after being combined with the ferrite composition. Optionally, the method further includes removing the solvent. The combination can be carried out by any suitable method such as blending, mixing, or stirring. In one embodiment, the polymer is melted and the ferrite composition and optional additives are dissolved or suspended in the melted polymer. In one embodiment, the components (including the polymer and the ferrite composition and optional additives) used to form the composite material can be combined by dissolving or suspending in a solvent to provide a mixture or solution.

[0048] The solvent (when included) is selected to dissolve the polymer, disperse the ferrite composition and any optional additives that may be present, and have an evaporation rate appropriate for shaping and drying. A non-exclusive list of possible solvents is xylene; toluene; methyl ethyl ketone; methyl isobutyl ketone; hexane; higher liquid linear alkanes such as heptane, octane, or nonane; cyclohexane; isophorone; various terpene-based solvents; or blended solvents. Exemplary solvents include xylene, toluene, methyl ethyl ketone, methyl isobutyl ketone, or hexane. In one embodiment, the solvent is xylene or toluene.

[0049] The concentration of the components of the composition in the solution or dispersion is not critical and will depend on the solubility of the components, the additive content used, the method of application, and other factors. Based on the total weight of the solution, the solution can contain 10 weight percent to 80 weight percent solids (all components except the solvent), or 50 weight percent to 75 weight percent solids.

[0050] Evaporate any solvent under ambient conditions or by forced or heated air, and cool the composition to provide a composite material. The composition can also be shaped, for example, by extrusion, molding, or casting.

[0051] The mixture can be molded, for example, by compression molding, injection molding, or reaction injection molding to form a composite material. In one embodiment, the mixture can be extruded or subjected to roll pressing techniques to form a composite material.

[0052] The composite material can be prepared by reaction injection molding of a thermosetting composition. Reaction injection molding can include mixing at least two streams to form a thermosetting composition and injecting the thermosetting composition into a mold, where the first stream can contain a catalyst and the second stream can contain an activator. One or both of the first and second streams or a third stream can contain monomers. One or both of the first and second streams or a third stream can contain a crosslinking agent, a ferrite composition, an additive, or a combination thereof. One or both of the ferrite composition and the additive can be added to the mold before injecting the thermosetting composition.

[0053] Mixing can be carried out in the top space of an injection molding machine. Mixing can be carried out in an in-line mixer. Mixing can be carried out during injection into the mold. Mixing can be carried out at a temperature greater than or equal to 0 °C to 200 °C, or 15 °C to 130 °C, or 0 °C to 45 °C, or 23 °C to 45 °C.

[0054] The mold can be maintained at a temperature greater than or equal to 0 °C to 250 °C, or 23 °C to 200 °C, or 45 °C to 250 °C, or 30 °C to 130 °C, or 50 °C to 70 °C. Filling the mold may take 0.25 minutes to 0.5 minutes, during which time the mold temperature may decrease. After the mold is filled, the temperature of the thermosetting composition may increase, for example, from a first temperature of 0 °C to 45 °C to a second temperature of 45 °C to 250 °C. Molding can be carried out at a pressure of 65 kPa to 350 kPa. Molding can be carried out for less than or equal to 5 minutes, or less than or equal to 2 minutes, or 2 seconds to 30 seconds. After polymerization is complete, the composite material can be removed at the mold temperature or at a reduced mold temperature. For example, the demolding temperature (T r ) can be less than or equal to 10 °C lower than the molding temperature (T m ) (T r ≤T m - 10 °C).

[0055] After removing the composite material from the mold, it can be post-cured. Post-curing can be carried out at a temperature of 100 °C to 150 °C, or 140 °C to 200 °C for greater than or equal to 5 minutes.

[0056] Also included herein are articles comprising a ferrite composition or composite material. The article can be a microwave device, such as an antenna or inductor. The article can be a transformer, inductor, or electromagnetic interference resistant material. The article can be an antenna such as a patch antenna, inverted-F antenna, or planar inverted-F antenna. The article can be a magnetic bus bar, such as a magnetic bus bar for wireless charging; NFC shielding material; or an electronic bandgap metamaterial. The article can be used in a frequency range of 1 GHz to 10 GHz, or 2 GHz to 12 GHz. The article can be used in a variety of devices that can operate in the ultra-high frequency range, such as high-frequency or microwave antennas, filters, inductors, circulators, or phase shifters. The article can be operable at a frequency greater than or equal to 1 GHz, or for ceramics such as bulk ceramics operable at a frequency of 1 GHz to 10 GHz, or for composite materials operable at a frequency of 2 GHz to 12 GHz. Such articles can be used in commercial and military applications, weather radar, scientific communication, wireless communication, autonomous vehicles, aircraft communication, space communication, satellite communication, or monitoring.

[0057] The following examples are provided to illustrate the present disclosure. The examples are illustrative only and are not intended to limit its scope. Examples

[0058] A series of 18H hexagonal ferrite compositions were fabricated. The chemical formula of the hexagonal ferrite is provided in Table 1. Table 1. Hexagonal ferrite Ba s Mg 2-x Zn x Ti3Fe 12 O 31 of the formula Embodiment x Formula 1 0.2 <![CDATA[Ba 5.1 Ni 1.8 Cu 0.2 Ti3Fe 11.7 O 31 > 2 0.4 <![CDATA[Ba 5.1 Ni 1.6 Cu 0.4 Ti3Fe 11.7 O 31 > 3 0.6 <![CDATA[Ba 5.1 Ni 1.4 Cu 0.6 Ti3Fe 11.7 O 31 > 4 1.0 <![CDATA[Ba 5.1 Ni 1.0 Cu 1.0 Ti3Fe 11.7 O 31 > 5 1.2 <![CDATA[Ba 5.1 Ni 0.8 Cu 1.2 Ti3Fe 11.7 O 31 > 6 1.3 <![CDATA[Ba 5.1 Ni 1.7 Cu 1.3 Ti3Fe 11.7 O 31 > 7 1.4 <![CDATA[Ba 5.1 Ni 1.6 Cu 1.4 Ti3Fe 11.7 O 31 > 8 1.5 <![CDATA[Ba 5.1 Ni 0.5 Cu 1.5 Ti3Fe 11.7 O 31 >

[0059] Each of these eight hexaferrite compositions is generally manufactured according to the following steps. The metal source compounds used are BaCO3 (>99.5%), NiO (>99.5%), CuO (>99.5%), TiO2 (>99.5%), and Fe2O3 (>99.2%). The metal source compounds are blended together in a wet planetary mill at a ratio to provide the desired formula. The mixture of metal source compounds is calcined by heating in air to 1,100 °C for a holding time of 4 hours. The calcined ferrite material is then crushed and screened through a 40# sieve. Then, the screened ferrite particles are subjected to grinding in a wet planetary mill to achieve a size of 0.5 micrometers to 10 micrometers. The ground ferrite particles are mixed with 0.5 weight percent to 5 weight percent of polyvinyl alcohol and then granulated into granules by screening through a 40# sieve. The granules are pressed at a pressure of 1 metric ton per square centimeter to form a green ferrite body. Two different shaped green bodies are formed: a ring for permeability and permittivity measurement (outer diameter of 7 millimeters (mm), inner diameter of 3 mm, and thickness of 3 mm to 3.5 mm) or a disk for hysteresis measurement (diameter of 6 mm).

[0060] The polyvinyl alcohol is first removed from the green body by heating in air at 600 °C for 2 hours, and then the green body is sintered in an oxygen atmosphere at 1,000 °C or 1,250 °C for 4 hours to obtain the hexaferrite composition. The oxygen flow rate is 0.5 liters per minute, the heating rate is 1 °C per minute to 5 °C per minute, and the cooling rate is 1 °C per minute to 5 °C per minute.

[0061] Hysteresis measurements are performed by a Vibrating Sample Magnetometer (VSM). The variation of magnetization with temperature is measured by a Physical Property Measurement System (PPMS) from Quantum Design at 50 Oe (3.98 kiloamperes per meter (kA / m)). The permeability / permittivity is measured in a coaxial air line by a vector network analyzer (VNA) at frequencies from 0.1 gigahertz (GHz) to 10 gigahertz (GHz) using the Nicholson-Ross-Weir (NRW) method.

[0062] Figure 2 Graph of magnetization (emu / g) versus temperature (°C) for Examples 1 to 8. Figure 2 Indicates that at temperatures from about 100 °C to 250 °C, it exhibits a magnetization greater than or equal to 1.5 (emu / g) (1.5 amperes square meter per kilogram (A·m 2Examples 6 to 8 of the magnetization intensity (in A / kg) can provide more desirable results than Examples 1 to 5, for example, in terms of magnetization intensity.

[0063] Figure 3 Graph of the real part of the permeability μ' versus the frequency (f) (in gigahertz (GHz)) for Examples 1 to 8. Figure 3 Indicates that Examples 6 to 8, which exhibit a maximum real part of the permeability less than 1.9 in the range of 0.1 GHz to 10 GHz, can provide more desirable results than Examples 1 to 5, for example, in terms of the real part of the permeability.

[0064] Figure 4 Graph of the imaginary part of the permeability μ'' versus the frequency (in GHz) for Examples 1 to 8. Figure 4 Indicates that Examples 6 to 8, which exhibit a maximum imaginary part of the permeability less than 1 in the range of 0.1 GHz to 10 GHz, can provide more desirable results than Examples 1 to 5, for example, in terms of the imaginary part of the permeability.

[0065] Table 2 provides the saturation magnetization intensity, coercivity, and Curie temperature for each of the ferrite compositions in Table 1. The saturation magnetization intensity, coercivity, and Curie temperature vary with the copper content (e.g., the molar ratio of copper to nickel in the ferrite composition). Table 2. Saturation Magnetization Intensity, Coercivity, and Curie Temperature

[0066] Tables 3 to 5 provide the real part of the permeability, magnetic loss tangent, dielectric constant, and dielectric loss tangent for each of the ferrite compositions in Table 1 at different frequencies. Example 2 exhibits a desirable combination of a high real part of the permeability and a low magnetic loss tangent at 4 GHz (1.50 and 0.04, respectively) and 5 GHz (1.67 and 0.04, respectively); and Example 3 exhibits a desirable combination of a high real part of the permeability and a low magnetic loss tangent at 4 GHz (1.52 and 0.04, respectively) and 5 GHz (1.76 and 0.04, respectively). The desirable combination of a high real part of the permeability and a low magnetic loss tangent can be, for example, greater than or equal to 1.50 and less than 0.05 (see Example 2 at 4 GHz or 5 GHz; and Example 3 at 4 GHz or 5 GHz), or greater than or equal to 1.50 and less than or equal to 0.04 (see Example 2 at 4 GHz or 5 GHz; and Example 3 at 4 GHz or 5 GHz). The dielectric constant (dielectric constant (ε')) of Examples 1 to 4 and 6 to 8 is 10 to 15 in the frequency band of 1 GHz to 9 GHz, and the dielectric loss tangent (ε'' / ε') is 0.0002 to 0.01 in the frequency band of 1 GHz to 5 GHz (except for Example 4 at 5 GHz, Example 6, and Example 8). Table 3 Table 4 Table 5 Example 9

[0067] A polymer-ferrite composite is manufactured using the hexagonal ferrite composition of Example 4. The calcined ferrite material of Example 4 is crushed and ground into a powder having an average particle size of 4 to 6 microns and then mixed with paraffin having different ferrite contents. The composite is formed into an annulus having an outer diameter of 7 mm, an inner diameter of 3 mm, and a thickness of 3 to 4 mm for magnetic and dielectric spectroscopy measurements by a vector network analyzer (VNA) using the Nicholson-Ross-Weir (NRW) method within a frequency range of 0.1 GHz to 18 GHz.

[0068] The results are provided in Table 6 and plotted in Figure 5 and Figure 6 respectively. Figure 5 is a plot of the real part of the magnetic permeability μ' and the imaginary part of the magnetic permeability μ'' versus frequency, and Figure 6 is a plot of the real part of the dielectric constant ε' and the imaginary part of the dielectric constant ε'' versus frequency. The polymer-ferrite composite can be used at frequencies from 1 GHz to 3 GHz and has a magnetic permeability of 1.2 to 1.5, a magnetic loss tangent of 0.06 to 0.08, a dielectric constant of 6 to 8, and a dielectric loss tangent of 0.002 to 0.006. Table 6

[0069] The following are non-limiting aspects of the present disclosure.

[0070] Aspect 1: A ferrite composition having the formula Ba x Ni 2-y Cu y Ti3Fe z O 31 where 4.5 ≤ x ≤ 5.5, 0 < y < 2 or 0.05 ≤ y ≤ 1.5, and 11 ≤ z ≤ 13.

[0071] Aspect 2: The ferrite composition according to Aspect 1, having the formula Ba x Ni 2-y Cu y Ti3Fe z O 31 where 5.0 ≤ x ≤ 5.1, 0.05 ≤ y ≤ 1.5, and 11.7 ≤ z ≤ 12.0.

[0072] Aspect 3: The ferrite composition according to Aspect 2, wherein x = 5.1.

[0073] Aspect 4: The ferrite composition according to Aspect 2 or 3, wherein z = 11.7.

[0074] Aspect 5: The ferrite composition according to any one of the foregoing aspects, having a Curie temperature greater than or equal to 200 °C, greater than or equal to 210 °C, greater than or equal to 220 °C, greater than or equal to 230 °C, greater than or equal to 240 °C, or greater than or equal to 250 °C.

[0075] Aspect 6: The ferrite composition according to any one of the foregoing aspects, having a coercivity less than 50 Oersteds (Oe) (3.98 kiloamperes per meter), less than 30 Oe (2.39 kiloamperes per meter), less than 15 Oe (1.19 kiloamperes per meter), less than 5 Oe (0.40 kiloamperes per meter), less than 4 Oe (0.32 kiloamperes per meter), less than 3 Oe (0.24 kiloamperes per meter), less than 2 Oe (0.16 kiloamperes per meter), or less than 1 Oe (0.08 kiloamperes per meter).

[0076] Aspect 7: The ferrite composition according to any one of the foregoing aspects, having an average particle size of 1 micrometer to 100 micrometers.

[0077] Aspect 8: The ferrite composition according to any one of the foregoing aspects, having a magnetic permeability (μ) of 1.5 to 2 at a frequency of 1 GHz to 9 GHz; a magnetic loss tangent (tanδ μ ) of less than 0.05 at a frequency of 1 GHz to 9 GHz; a dielectric constant (ε) of 10 to 15 at a frequency of 1 GHz to 9 GHz; a dielectric loss tangent (tanδ ε ) of less than 0.01, less than 0.08, or less than 0.004 at a frequency of 1 GHz to 9 GHz; a cut-off frequency (resonance frequency, f r ) greater than 10 GHz; or a combination of the foregoing.

[0078] Aspect 9: The ferrite composition according to any one of the foregoing aspects, having in-plane easy magnetization, an 18H structure, or a combination thereof.

[0079] Aspect 10: A method of manufacturing a ferrite composition, comprising calcining a blended metal source compound for the ferrite composition according to any one of the foregoing aspects; reducing the particle size of the calcined source compound to obtain particles having an average particle size of 0.5 micrometers to 100 micrometers or 0.5 micrometers to 10 micrometers; granulating a mixture of the particles and a binder to obtain a granulated body; pressing the granulated body into a green compact; and sintering the green compact to form the ferrite composition.

[0080] Aspect 11: The method according to aspect 10, wherein the calcination is carried out at 900 °C to 1,200 °C for 0.5 hour to 20 hours; the calcination is carried out in an atmosphere of air, nitrogen, oxygen, or a combination thereof; the sintering is carried out at 1,000 °C to 1,300 °C for 1 hour to 20 hours; the sintering is carried out in an atmosphere of air, nitrogen, oxygen, or a combination thereof; the sintering is carried out at a heating rate of 1 °C / minute to 5 °C / minute, a cooling rate of 1 °C / minute to 5 °C / minute, or a combination thereof; reducing the particle size includes crushing the calcined source compound, grinding the calcined source compound, or a combination thereof; or a combination of the foregoing.

[0081] Aspect 12: The method according to aspect 10 or 11, further comprising classifying the particles by size.

[0082] Aspect 13: The method according to any one of aspects 10 to 12, further comprising blending the metal source compounds.

[0083] Aspect 14: The method according to any one of aspects 10 to 13, wherein the binder is polyvinylpyrrolidone, poly(vinyl alcohol), polyacrylamide, poly(acrylic acid), polyethylene glycol, poly(ethylene oxide), cellulose acetate, starch, poly(propylene carbonate), poly(vinyl butyral), or a combination thereof.

[0084] Aspect 15: A composite material, comprising a polymer matrix and a ferrite composition according to any one of aspects 1 to 9, wherein the particle size of the ferrite composition is 0.5 micrometers to 30 micrometers.

[0085] Aspect 16: The composite material according to aspect 15, comprising 5 volume percent to 95 volume percent of hexagonal ferrite based on the total volume of the composite material.

[0086] Aspect 17: The composite material according to aspect 15 or 16, wherein the polymer matrix comprises poly(vinylidene fluoride), polytetrafluoroethylene, polyethylene, high-density polyethylene, low-density polyethylene, polymethyl methacrylate, poly(ether ether ketone), poly(ether sulfone), or a combination thereof.

[0087] Aspect 18: An article comprising a ferrite composition according to any one of Aspects 1 to 9.

[0088] Aspect 19: The article according to Aspect 18, wherein the article is an antenna, inductor, transformer, or electromagnetic interference resistant material.

[0089] Aspect 20: The article according to Aspect 18 or 19, wherein the article is a microwave device.

[0090] Generally, the compositions, methods, and articles may alternatively include any of the ingredients, steps, or components disclosed herein, consist of any of the ingredients, steps, or components disclosed herein, or consist essentially of any of the ingredients, steps, or components disclosed herein. The compositions, methods, and articles may additionally or alternatively be formulated, practiced, or manufactured without or substantially without any ingredient, step, or component that is not necessary for the achievement of the functions or purposes of the present claims.

[0091] Terms without an explicit quantifier do not denote a limitation in quantity but rather the presence of at least one of the items mentioned. Unless otherwise explicitly indicated by context, the term "or" means "and / or". Endpoints of a full range of the same component or property include the endpoints, may be combined independently, and include all intermediate points. The disclosure of a narrower range or a more specific group in addition to a broader range is not a disclaimer of the broader range or larger group. "A combination thereof" is open-ended and includes combinations of one or more of the specified elements optionally together with one or more similar unspecified elements.

[0092] Unless otherwise defined, technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure pertains. The term "combination" includes blends, mixtures, alloys, reaction products, etc. Dielectric constant and magnetic permeability as used herein may be determined at a temperature of 23 °C.

[0093] Throughout the specification, reference to "one aspect", "some aspects", "one embodiment", etc. means that a particular element (e.g., a feature, structure, step, or property) described in connection with the aspect is included in at least one aspect described herein and may or may not be present in other aspects. Thus, while certain combinations of features have been described, it will be understood that these combinations are for illustrative purposes only and that any combination of any of these features may be explicitly or equivalently employed alone in any combination and in full accordance with one aspect, or in combination with any other of the features disclosed herein. Any and all such combinations are contemplated herein and are considered to be within the scope of this disclosure.

[0094] Although the present disclosure has been described with reference to exemplary aspects, those skilled in the art will understand that various changes can be made and equivalents can replace its elements without departing from the scope of the present disclosure. In addition, many modifications can be made to adapt a particular situation or material to the teachings without departing from its essential scope. Therefore, it is intended that the present disclosure not be limited to the particular aspects disclosed as the best mode or the only mode contemplated for carrying out the invention, but that the present disclosure will include all aspects falling within the scope of the appended claims.

Claims

1. A ferrite composition having the following formula Ba x Ni 2-y Cu y Ti3Fe z O 31 , wherein 4.5 ≤ x ≤ 5.5, 0 < y < 2 or 0.05 ≤ y ≤ 1.5, and 11 ≤ z ≤ 13.

2. The ferrite composition according to claim 1, having the following formula Ba x Ni 2-y Cu y Ti3Fe z O 31 , wherein 5.0 ≤ x ≤ 5.1, 0.05 ≤ y ≤ 1.5, and 11.7 ≤ z ≤ 12.

0.

3. The ferrite composition according to claim 2, wherein x = 5.

1.

4. The ferrite composition according to claim 2 or 3, wherein z = 11.

7.

5. The ferrite composition according to any one of the preceding claims, having a Curie temperature greater than or equal to 200 °C, greater than or equal to 210 °C, greater than or equal to 220 °C, greater than or equal to 230 °C, greater than or equal to 240 °C, or greater than or equal to 250 °C.

6. The ferrite composition according to any one of the preceding claims, having a coercivity less than 50 Oe (3.98 kA / m), less than 30 Oe (2.39 kA / m), less than 15 Oe (1.19 kA / m), less than 5 Oe (0.40 kA / m), less than 4 Oe (0.32 kA / m), less than 3 Oe (0.24 kA / m), less than 2 Oe (0.16 kA / m), or less than 1 Oe (0.08 kA / m).

7. The ferrite composition according to any one of the preceding claims, having an average grain size of 1 to 100 microns.

8. The ferrite composition according to any one of the preceding claims, having a magnetic permeability (μ) of 1.5 to 2 at a frequency of 1 GHz to 9 GHz; a magnetic loss tangent (tanδ μ ) less than 0.05 at a frequency of 1 GHz to 9 GHz; A dielectric constant (ε) of 10 to 15 at frequencies from 1 GHz to 9 GHz; A dielectric loss tangent (tanδ) of less than 0.01, less than 0.08, or less than 0.004 at frequencies from 1 GHz to 9 GHz ε ); A cut-off frequency (resonance frequency, f r ) greater than 10 GHz; or The foregoing combination.

9. The ferrite composition according to any one of the foregoing claims, having in-plane easy magnetization, a 18H structure, or a combination thereof.

10. A method of manufacturing a ferrite composition, comprising: Calcine the blended metal source compound for the ferrite composition described in any one of the foregoing claims; Reduce the particle size of the calcined source compound to obtain particles having an average particle size of 0.5 micrometers to 100 micrometers or 0.5 micrometers to 10 micrometers; Granulate the mixture of the particles and the binder to obtain a granulated body; Press the granulated body into a green compact; and Sinter the green compact to form the ferrite composition.

11. The method according to claim 10, wherein The calcination is carried out at 900 °C to 1,200 °C for 0.5 hours to 20 hours; The calcination is carried out in an atmosphere of air, nitrogen, oxygen, or a combination thereof; The sintering is carried out at 1,000 °C to 1,300 °C for 1 hour to 20 hours; The sintering is carried out in an atmosphere of air, nitrogen, oxygen, or a combination thereof; The sintering is carried out at a heating rate of 1 °C / minute to 5 °C / minute, a cooling rate of 1 °C / minute to 5 °C / minute, or a combination thereof; Reducing the particle size includes crushing the calcined source compound, grinding the calcined source compound, or a combination thereof; or The foregoing combination.

12. The method according to claim 10 or 11, further comprising classifying the particles by size.

13. The method according to any one of claims 10 to 12, further comprising blending the metal source compounds.

14. The method according to any one of claims 10 to 13, wherein the binder is polyvinylpyrrolidone, poly(vinyl alcohol), polyacrylamide, poly(acrylic acid), polyethylene glycol, poly(ethylene oxide), cellulose acetate, starch, poly(propylene carbonate), poly(vinyl butyral), or a combination thereof.

15. A composite material, comprising: A polymer matrix; and The ferrite composition according to any one of claims 1 to 9, wherein the particle size of the ferrite composition is from 0.5 micrometers to 30 micrometers.

16. The composite material according to claim 15, comprising 5 vol% to 95 vol% of hexagonal ferrite based on the total volume of the composite material.

17. The composite material according to claim 15 or 16, wherein the polymer matrix comprises polyvinylidene fluoride, polytetrafluoroethylene, polyethylene, high density polyethylene, low density polyethylene, polymethyl methacrylate, polyether ether ketone, polyether sulfone, or a combination thereof.

18. An article comprising the ferrite composition according to any one of claims 1 to 9.

19. The article according to claim 18, wherein the article is an antenna, an inductor, a transformer, or an electromagnetic interference resistant material.

20. The article according to claim 18 or 19, wherein the article is a microwave device.

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