Polycrystalline 18h hexaferrite, method for the production thereof and use thereof

Abstract

There remains a need for a ferrite material with low magnetic loss, high permeability, and low permittivity and dielectric loss in the gigahertz range, and a method of making the ferrite material.SOLUTION: The polycrystalline ferrite composition is represented by the M5Me2Ti3Fe12O31 formula, wherein M is Ba2 +, Sr2 +, or a combination thereof; Me is Mg2 +, Zn2 +, Cu2 +, Co2 +, or a combination thereof; and has an average grain size of 1 micrometer to 100 micrometers. The composite comprises a polymer matrix and the polycrystalline ferrite composition described above. Methods of making the polycrystalline ferrite compositions and composites thereof are also disclosed.SELECTED DRAWING: None

Description

[Technical Field]

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS This application claims the benefit of U.S. Application No. 62 / 972,116, filed February 10, 2020, which is incorporated herein by reference in its entirety. [Background technology]

[0002] FIELD OF THE DISCLOSURE This disclosure relates generally to polycrystalline 18H hexaferrite compositions, particularly those having high frequency magnetic permeability, composites (composite materials) including polycrystalline 18H hexaferrite compositions, methods of making same, and uses thereof.

[0003] Improved performance and miniaturization are needed to meet the ever-increasing demands of devices used in ultra-high frequency (UHF), L-band, and S-band applications, which are of particular interest to various commercial and defense industries. Compact-sized antenna elements are constantly being developed as key components of radar and modern wireless communication systems. However, developing ferrite materials for use in such high-frequency applications is challenging because most ferrite materials exhibit relatively high magnetic losses at high frequencies. Manufacturing methods for ferrite materials can affect the crystalline structure of the material and, therefore, improve performance. Summary of the Invention [Problem to be solved by the invention]

[0004] Therefore, there remains a need for ferrite materials with low magnetic loss, high magnetic permeability, and low permittivity and dielectric loss in the gigahertz range, as well as methods for making the same. [Means for solving the problem]

[0005] [Brief summary] The polycrystalline ferrite composition is M5Me2Ti3Fe12 O 31 wherein M is Ba 2+ , Sr 2+ or a combination thereof; Me is Mg 2+ , Zn 2+ , Cu 2+ , Co 2+ or a combination thereof; and having an average particle size of 1 micrometer to 100 micrometers.

[0006] The method for producing the polycrystalline ferrite composition includes the steps of calcinating blended metal raw material compounds for the polycrystalline ferrite composition; reducing the particle size of the calcined raw material compounds to obtain particles having an average particle size of 0.5 micrometers to 10 micrometers; granulating the mixture of particles and binder to obtain granules; compressing the granules into a green body; and sintering the green body to form the polycrystalline ferrite composition.

[0007] The composite includes a polymer matrix and the polycrystalline ferrite composition described above.

[0008] A method for making the composite includes mixing a polymer, the polycrystalline ferrite composition, optionally a solvent, and optionally an additive composition to form a composite; and optionally removing the solvent from the composite.

[0009] Articles comprising the polycrystalline ferrite composition or polycrystalline ferrite composite described above are also described, including antennas, inductors, transformers, or anti-electromagnetic interference materials.

[0010] The accompanying drawings are exemplary embodiments provided to illustrate the disclosure herein. The drawings are illustrative examples and are not intended to limit devices made in accordance with the present disclosure to the materials, conditions, or process parameters described herein. [Brief explanation of the drawings]

[0011] [Figure 1] Figure 1 is a schematic diagram of one half of an 18-layer stacking sequence of a unit cell of 18H hexaferrite BaTiMeFeO, showing three layers of half Y blocks, three layers of hexagonal barium titanate (HBT), and three layers of half Y blocks. The actual distribution of interstitial cations may vary to provide a path for magnetic coupling along the c axis. The HBT layers may also contain Fe ions and / or Me = Mg, Zn, Co, Cu. [Figure 2] FIG. 2 presents a graph showing magnetic hysteresis loop data for exemplary polycrystalline ferrites Ba5Mg2-xZnxTi3Fe12O31 (x varies from 0 to 2) disclosed in Table 1. [Figure 3] FIG. 3 shows the magnetic permeability spectra of samples of exemplary polycrystalline ferrite Ba5Mg2-xZnxTi3Fe12O31 (x=0 (#1-1), 0.25 (#2-1), 0.5 (#3-1), and 0.7 (#4-1)) sintered in O2 at 1150 °C for 4 hours. [Figure 4] FIG. 4 shows the magnetic permeability spectra of samples of exemplary polycrystalline ferrite Ba5Mg2-xZnxTi3Fe12O31 (x=0 (#1-2), 0.25 (#2-2), 0.5 (#3-2), and 0.7 (#4-2)) sintered in O2 at 1250 °C for 4 hours. [Figure 5] FIG. 5 shows the magnetic permeability spectrum of an exemplary polycrystalline ferrite sample Ba5Mg2-xZnxTi3Fe12O31 (x=0 (#1-3)) sintered in O2 at 1200 °C for 4 hours. DETAILED DESCRIPTION OF THE INVENTION

[0012] [Detailed explanation] We have discovered that polycrystalline 18H-type ferrite compositions having an average grain size of 1 micrometer to 100 micrometers exhibit low magnetic loss tangents and high permeabilities at high frequencies, while also exhibiting low dielectric loss tangents and high permittivity. Advantageously, the polycrystalline 18H-type ferrite compositions are cost-effective to manufacture because they do not require expensive elements, such as rare earths or precious elements. When compounded with polymers, the ferrite compositions result in composites with low magnetic loss, high permeability, low permittivity, and low dielectric loss. The ferrite compositions and composites described herein are particularly useful for applications such as antenna substrates, inductor cores, and EMI suppressors over a wide frequency range (0.5 to 10 GHz).

[0013] The polycrystalline ferrite composition is M5Me2Ti3Fe 12 O 31 where M is Ba 2+ , Sr 2+ or a combination thereof; and Me is Mg 2+ , Zn 2+ , Cu 2+ , Co 2+ or a combination thereof. The polycrystalline ferrite composition can have an 18H structure. The polycrystalline ferrite composition can have easy in-plane (basal c-plane) magnetization (also known as planar anisotropy).

[0014] The particle size of the polycrystalline ferrite composition is selected to provide the polycrystalline ferrite composition with magnetic and dielectric properties suitable for a given application. The particle size can be controlled by controlling the ferrite synthesis conditions, such as the temperature, heating time, and heating or cooling rate. The average particle size of the ferrite composition can be 1 micrometer to 100 micrometers, preferably 5 micrometers to 50 micrometers. The average particle size can be determined, for example, by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), or a combination thereof.

[0015] The polycrystalline ferrite composition may have the formula: (Ba 1-x Sr x )5Mg 2-y Me' y Ti3Fe 12-z O 31 In the formula, Me' is Zn 2+ , Cu 2+ , Co 2+ or combinations thereof, where x=0 to 1.5, y=0 to 1.8, and z=-4 to +4. Ferrite compositions of this formula advantageously exhibit very low losses combined with unique resonant peaks. In certain compositions, y=0 to 1.0 and / or x=0.

[0016] In one aspect, the polycrystalline ferrite composition has the formula Ba5Zn2Ti3Fe 12 O 31 , Ba5Mg2Ti3Fe 12 O 31 , Ba5Co2Ti3Fe 12 O 31 , Ba5Cu2Ti3Fe 12 O 31 , Ba 5.1 (Ni 1.1 Cu 0.4 )Ti 2.7 Fe 12.3 Mn 0.4 O 31 ], or Ba 5.4 (Mg 1.3 Zn 0.7 )Ti 2.9 Fe 11.7 O 31 can be excluded.

[0017] The polycrystalline ferrite composition has a magnetic permeability (μ) of at least 2 at frequencies between 1 and 4 GHz, preferably at least 5 at frequencies between 1 and 4 GHz; a magnetic loss tangent (tanδ) of less than 0.05 at frequencies between 1 and 4 GHz, preferably less than 0.02 at frequencies between 1 and 4 GHz; μ) (more preferably while simultaneously maintaining a high magnetic permeability of at least 2 at that frequency); a dielectric constant (ε) of at least 13-16 at frequencies from 1 to 4 GHz, preferably at least 13-15 at frequencies from 1 to 4 GHz; a dielectric loss tangent (tanδ) of less than 0.004 at frequencies from 1 to 3 GHz, preferably less than 0.003 at frequencies from 1 to 6 GHz. ε ); Magnetic loss coefficient (tanδ) of less than 0.02 at frequencies of 1 to 4 GHz or 2 to 6 GHz μ / μ'); cutoff frequency (resonance frequency, f r ); Snoek product greater than 9 GHz, preferably greater than 12 GHz (where Snoek product = u' x f r or a combination of the aforementioned properties.

[0018] The polycrystalline hexaferrite particles can be produced by any suitable method. Examples of methods for producing polycrystalline ferrite compositions include a single-fired ceramic method and a wet chemical method. Another example of a method for producing the polycrystalline ferrite composition can include calcining blended metal raw material compounds for a desired polycrystalline ferrite composition; reducing the particle size of the calcined raw material compounds to obtain particles having an average particle size of 0.5 micrometers to 10 micrometers; granulating a mixture of the particles and a binder to obtain granules; compressing the granules into a green body; and sintering the green body to form the polycrystalline ferrite composition.

[0019] Metal source compounds are compounds required for the synthesis of ferrite. Metal source compounds can be selected based on factors such as cost and availability. Examples of source compounds for a given metal include the oxide, carbonate, acetate, nitrate, sulfate, or chloride of that metal. Typical precursors include barium carbonate (e.g., BaCO), iron oxide (e.g., α-FeO), magnesium oxide (e.g., MgO), titanium oxide (e.g., TiO), and zinc oxide (e.g., ZnO). Additional iron precursors include Fe(NO3)3·9H2O, FeCl3·6H2O, and Fe2(SO4)3·H2O; possible cobalt precursors include cobalt oxide (Co3O4), Co(CH3COO)2·4H2O, Co(NO3)2·6H2O, and CoCl2·6H2O; and additional zinc precursors include Zn(NO3)2·6H2O, ZnCl2, and ZnSO4·7H2O. Metal source compounds can be combined in amounts to achieve the desired metal stoichiometry.

[0020] Calcining the blended metal raw compounds can be carried out at an appropriate temperature and for a time to synthesize the desired ferrite and achieve the desired particle size. For example, the temperature can be 800°C to 1300°C, or 900°C to 1200°C, or 1000°C to 1200°C. The time can be, for example, 0.5 hours to 200 hours, or 1 hour to 15 hours. Calcination is carried out in an atmosphere of air, nitrogen, oxygen, or a combination thereof. The heating or cooling rate for calcination in the furnace can also be selected to obtain the desired ferrite, particle size, or structural form (morphology). For example, the heating or cooling rate can be 2 to 3°C / min.

[0021] The particle size of the calcined blend can be reduced by any suitable method. Examples of particle size reduction methods include crushing, grinding, milling, mechanical pulverization, and combinations thereof. Examples of particle size reduction equipment include media mills, ball mills, two-roll mills, three-roll mills, bead mills, air jet mills, and cryogenic grinders. After particle size reduction, the particles can be subjected to a sizing procedure, such as sieving, to alter the particle size distribution.

[0022] The mixture of ferrite particles and binder can be granulated by any suitable method, such as spray-drying granulation or vibration extrusion granulation. For example, a slurry of ferrite particles, binder, and various additives, if desired, can be dispersed in a solvent, such as water, and then the slurry can be spray-dried using a spray dryer or the like to produce granules. Alternatively, the ferrite particles, binder, and various additives, if desired, can be mixed and granulated in an agitator granulator to produce a granulated powder. The granulated powder can then be extruded and granulated in a vibration granulator to produce granules.

[0023] The binder is selected so that it can be removed from the green body by heating and, in some cases, dissolved in a solvent. Examples of binders include polyvinylpyrrolidone (PVP), poly(vinyl alcohol) (PVA), polyvinyl butyral (PVB), polyacrylamide (PAM), poly(acrylic acid) (PAA), polyethylene glycol (PEG), polyethylene oxide (PEO), cellulose acetate, starch, polypropylene carbonate, polyvinyl acetate (PVAc), and combinations thereof. Preferably, the binder is PVA, PVB, or a combination thereof.

[0024] The granulated ferrite composition is compressed into a predetermined shape by various compression molding methods, such as a single press, a double press, a floating die, or a drawing method, to obtain a green body. The compression machine is appropriately selected depending on the size, shape, and amount of the green body, and may be, for example, a mechanical press, a hydraulic press, or a servo press. The compression pressure for forming the green body is 0.3 to 3 metric tons per square centimeter (MT / cm). 2 ), or 0.5 to 2MT / cm 2 It can be.

[0025] The green body can then be sintered in a suitable atmosphere to form a polycrystalline ferrite composition. Sintering can occur at sintering temperatures of 800 to 1,300°C, 900 to 1,250°C, or 1,000 to 1,200°C. Sintering can occur for sintering times of 1 to 20 hours, or 2.55 to 12 hours. The atmosphere can be air, nitrogen, oxygen, or a combination thereof. Sintering can be performed at a heating rate of 1°C / min to 5°C / min and / or a cooling rate of 1°C / min to 5°C / min.

[0026] The composite may include a polycrystalline ferrite composition and a polymer matrix.

[0027] The composite can include 5 to 95 volume percent (vol%), 10 to 90 volume percent, 20 to 80 volume percent, or 30 to 70 volume percent of the polycrystalline ferrite composition, based on the total volume of the composite. The composite can include 5 to 95 volume percent, 10 to 90 volume percent, 20 to 80 volume percent, or 30 to 70 volume percent of the polymer, based on the total volume of the composite.

[0028] The 18H ferrite particles present in the composite have a particle size of 0.5 micrometers to 30 micrometers, preferably 1 micrometer to 10 micrometers. Particle size can be determined using a Horiba LA-910 laser light scattering PSD analyzer or equivalent, or in accordance with ASTM D4464-15. The reported particle size is the median D50 volumetric particle size. Appropriately sized 18H ferrite particles can be obtained by any suitable method. For example, any suitable ceramic or chemical process can be used to synthesize 18H ferrite particles of the desired size. Alternatively, 18H ferrite particles can be obtained by crushing and grinding sintered ferrite bulk material obtained by the methods described above.

[0029] The polymer matrix can comprise a thermosetting or thermoplastic polymer. As used herein, the term "thermoplastic" refers to a material that is plastic or deformable when heated, melts to a liquid, and cools to a brittle, glassy state when cooled sufficiently. Examples of thermoplastic polymers that can be used include cyclic olefin polymers (which include polynorbornenes and copolymers containing norbornenyl units, e.g., copolymers of a cyclic monomer such as norbornene with an acyclic olefin such as ethylene or propylene), fluoropolymers (e.g., polyvinyl fluoride (PVF), polyvinylidene fluoride (PVDF), fluorinated ethylene propylene (FEP), polytetrafluoroethylene (PTFE), poly(ethylene-tetrafluoroethylene) (PETFE), or perfluoroalkoxy (PFA)), polyacetals (e.g., polyoxyethylene and polyoxymethylene), poly(C 1-6 alkyl) acrylates, polyacrylamides (including unsubstituted and mono-N- or di-N-(C 1-8alkyl)acrylamides), polyacrylonitrile, polyamides (e.g., aliphatic polyamides, polyphthalamides, or polyaramids), polyamideimides, polyanhydrides, polyarylene ethers (e.g., polyphenylene ether), polyarylene ether ketones (e.g., polyetheretherketone (PEEK) and polyetherketoneketone (PEKK)), polyarylene ketones, polyarylene sulfides (e.g., polyphenylene sulfide (PPS)), polyarylene sulfones (e.g., polyethersulfone (PES), polyphenylene sulfone (PPS), etc.), polybenzothiazole, poly Examples of suitable polymers include tribenzoxazole, polybenzimidazole, polycarbonates (including homopolycarbonates or polycarbonate copolymers such as polycarbonate-siloxane, polycarbonate-ester, or polycarbonate-ester-siloxane), polyesters (e.g., polyethylene terephthalate, polybutylene terephthalate, polyarylate, or polyester copolymers such as polyester-ether), polyetherimides (e.g., copolymers such as polyetherimide-siloxane copolymers), polyimides (e.g., copolymers such as polyimide-siloxane copolymers), poly(C 1-6 alkyl) methacrylates, polyalkylacrylamides (e.g., unsubstituted and mono-N- or di-N-(C 1-8(alkyl)acrylamides), polyolefins (e.g., polyethylenes such as high density polyethylene (HDPE), low density polyethylene (LDPE), and linear low density polyethylene (LLDPE), polypropylenes and their halogenated derivatives (e.g., polytetrafluoroethylene), and copolymers thereof, e.g., ethylene-α-olefin copolymers), polyoxadiazoles, polyoxymethylenes, polyphthalides, polysilazanes, polysiloxanes (silicones), polystyrenes (e.g., copolymers such as acrylonitrile-butadiene-styrene (ABS)) or methyl methacrylate-butadiene-styrene (MBS)), polysulfides, polysulfonamides, polysulfonates, polysulfones, polythioesters, polytriazines, polyureas, polyurethanes, vinyl polymers (e.g., polyvinyl alcohol, polyvinyl esters, polyvinyl ethers, polyvinyl halides) (e.g., polyvinyl chloride), polyvinyl ketones, polyvinyl nitriles, or polyvinyl thioethers), paraffin waxes, and the like. Combinations comprising at least one of the foregoing thermoplastic polymers can be used.

[0030] Thermoset polymers are derived from thermosetting monomers or prepolymers (resins), which can be polymerized or cured to become irreversibly hard and insoluble, and polymerization or curing can be induced by exposure to heat or radiation (e.g., ultraviolet light, visible light, infrared light, or electron beam (e-beam) radiation). Thermosetting polymers include alkyds, bismaleimide polymers, bismaleimide triazine polymers, cyanate ester polymers, benzocyclobutene polymers, benzoxazine polymers, diallyl phthalate polymers, epoxies, hydroxymethylfuran polymers, melamine-formaldehyde polymers, phenolic resins (including phenol-formaldehyde polymers such as novolacs and resols), benzoxazines, polydienes such as polybutadiene (including diene homopolymers and copolymers thereof, e.g., poly(butadiene-isoprene)), polyisocyanates, polyureas, polyurethanes, triallyl cyanurate polymers, triallyl isocyanurate polymers, certain silicones, and polymerizable prepolymers (e.g., prepolymers having ethylenic unsaturation, e.g., unsaturated polyesters, unsaturated polyimides). Prepolymers can be, for example, styrene, α-methylstyrene, vinyltoluene, chlorostyrene, acrylic acid, (meth)acrylic acid, (C 1-6 alkyl) acrylate, (C 1-6 It can be polymerized, copolymerized, or crosslinked with reactive monomers such as (alkyl)methacrylate, acrylonitrile, vinyl acetate, allyl acetate, triallyl cyanurate, triallyl isocyanurate, or acrylamide.

[0031] The polymer can include at least one of a fluoropolymer (e.g., polyvinylidene fluoride (PVDF) or polytetrafluoroethylene (PTFE)), a polyolefin (e.g., polyethylene (PE), high density polyethylene (HDPE), low density polyethylene (LDPE)), a poly(arylene ether ketone) (e.g., polyether ether ketone (PEEK)), a polyalkyl(meth)acrylate (e.g., polymethyl methacrylate (PMMA)), or a poly(ether sulfone).

[0032] The composite may contain additional additives such as dielectric fillers or flame retardants, so long as the additives are less than 5% by volume of the total volume of the composite.

[0033] Particulate dielectric fillers can be used to adjust the dielectric constant, dissipation factor, coefficient of thermal expansion, and other properties of the composite. Examples of 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, beryllia, alumina, alumina trihydrate, magnesia, mica, talc, nanoclay, magnesium hydroxide, and combinations comprising at least one of the foregoing.

[0034] Flame retardants can be halogenated or non-halogenated. Exemplary inorganic flame retardants are metal hydroxides, such as hydroxides of metals such as Mg, Ca, Al, Fe, Zn, Ba, Cu, Ni, etc., or combinations comprising at least one of these. Specific compounds include aluminum hydroxide, magnesium hydroxide, calcium hydroxide, iron hydroxide, zinc hydroxide, copper hydroxide, and nickel hydroxide; calcium aluminate hydrate, gypsum dihydrate, zinc borate, and barium metaborate. Organic flame retardants can be used instead of or in addition to inorganic flame retardants. Examples of inorganic flame retardants include melamine cyanurate, fine particle size melamine polyphosphate, various other phosphorus-containing compounds such as aromatic phosphinates, diphosphinates, phosphonates, and phosphates, certain polysilsesquioxanes, siloxanes, and halogenated compounds such as hexachloroendomethylenetetrahydrophthalic acid (HET acid), tetrabromophthalic acid, and dibromoneopentyl glycol, for example.

[0035] The composite (composite material) can have an operating frequency of 1 GHz to 10 GHz.

[0036] The composite has a magnetic loss tangent (tanδ) of less than 0.02 at frequencies between 1 and 8 GHz. μ Such a magnetic material having low magnetic loss can be advantageously used in high frequency applications such as antenna applications.

[0037] The composite may have a magnetic permeability (μ) of at least 1.5 at frequencies between 1 and 10 GHz.

[0038] The composite (composite material) may have a dielectric constant (ε) of 5 to 6 at frequencies of 1 to 10 GHz.

[0039] The composite has a dielectric loss tangent (tanδ) of less than 0.004 at frequencies between 1 and 10 GHz. ε ) can be included.

[0040] The composite (composite material) has a magnetic loss coefficient (tanδ) of less than 0.01 or less than 0.008 at a frequency of 1 to 8 GHz or at a frequency of 2 to 10 GHz. μ / μ′).

[0041] The composite (composite material) has a cutoff frequency (resonant frequency, f r ) can be included.

[0042] A method for making a composite (composite material) includes combining a polymer, a polycrystalline ferrite composition, optionally a solvent, and optionally an additive to form a composition. The polymer can be melted before or after being combined with the polycrystalline ferrite composition. Optionally, the method can further include removing the solvent. The combining can be by any suitable method, such as blending, mixing, or stirring. In one embodiment, the polymer is melted and the polycrystalline ferrite composition and optional additives are dissolved or suspended in the molten polymer. In one embodiment, the components used to form the composite (including the polymer, polycrystalline ferrite composition, and optional additives) can be combined by dissolving or suspending in a solvent to provide a mixture or solution.

[0043] The solvent, if included, is selected so as to dissolve the polymer, disperse the polycrystalline ferrite composition and any other additives that may be present, and have a convenient evaporation rate for molding and drying. A non-limiting list of possible solvents is xylene; toluene; methyl ethyl ketone; methyl isobutyl ketone; hexane and higher liquid linear alkanes such as heptane, octane, nonane, etc.; cyclohexane; isophorone; various terpene solvents; and mixed solvents. Specific exemplary solvents include xylene, toluene, methyl ethyl ketone, methyl isobutyl ketone, and hexane, and more particularly xylene and toluene.

[0044] 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 levels used, the method of application, and other factors. Generally, the solution will contain 10 to 80% by weight solids (all components other than solvent), more particularly 50 to 75% by weight solids, based on the total weight of the solution.

[0045] The solvent is evaporated under ambient conditions or by forced or heated air, and the composition is cooled to provide a composite. The composition can also be shaped by known methods, such as extrusion, molding, or casting.

[0046] The mixture can be molded to form a composite, for example, by compression molding, injection molding, reaction injection molding, etc. The mixture can alternatively be extruded or subjected to a rolling process to form a composite.

[0047] The composite material can be prepared by reaction injection molding 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 a first stream can include a catalyst and a second stream can include an activator. One or both of the first and second streams, or a third stream, can include a monomer. One or both of the first and second streams, or a third stream can include at least one of a crosslinker, a polycrystalline ferrite composition, and an additive. One or both of the polycrystalline ferrite composition and the additive can be added to the mold before injecting the thermosetting composition.

[0048] The mixing can occur in the headspace of an injection molding machine. The mixing can occur in an in-line mixer. The mixing can occur during injection into the mold. The mixing can occur at temperatures from 0 to 200°C or higher, or from 15 to 130°C or higher, or from 0 to 45°C or higher, or from 23 to 45°C or higher.

[0049] The mold (die) can be maintained at a temperature of 0°C to 250°C, 23 to 200°C, 45 to 250°C, 30 to 130°C, or 50 to 70°C. Filling the mold can take 0.25 to 0.5 minutes, during which time the mold temperature can decrease. After the mold is filled, the temperature of the thermosetting composition can be increased, for example, from a first temperature of 0 to 45°C to a second temperature of 45 to 250°C. Molding can be performed at a pressure of 65 to 350 kilopascals (kPa). Molding can be performed for 5 minutes or less, 2 minutes or less, or 2 to 30 seconds. After polymerization is complete, the composite can be removed from the mold at the temperature or at a reduced mold temperature. For example, at a release temperature T r is the molding temperature T m It may be 10°C or even lower than r ≦T m -10℃).

[0050] After the composite is removed from the mold, it can be post-cured at a temperature of 100 to 150°C, or 140 to 200°C, for 5 minutes or more.

[0051] Also included herein are articles containing the polycrystalline ferrite composition or composite described above. The article can be a microwave device, such as an antenna or inductor. The article can be a transformer, inductor, or anti-electromagnetic interference material. The article can be an antenna, such as a patch antenna, an inverted-F antenna, or a planar inverted-F antenna. The article can be a magnetic busbar, such as a magnetic busbar for wireless charging; an NFC shielding material; or an electronic bandgap metamaterial. The article can be intended for use at frequencies in the 0.1 to 4 gigahertz range, or in the 0.5 to 2 gigahertz range. The article can be used in various devices operating in the ultra-high frequency range, such as radio frequency or microwave antennas, filters, inductors, circulators, or phase shifters. The article can be operated at frequencies above 1 GHz, or at frequencies between 1 and 6 GHz. Such articles can be used in commercial and military applications, weather radar, scientific communications, wireless communications, autonomous vehicles, aircraft communications, space communications, satellite communications, or surveillance.

[0052] The following examples are provided to illustrate the present disclosure. The following examples are for illustrative purposes only and are not intended to limit the scope of the present invention. [Example]

[0053] A series of 18H hexaferrite compositions have been prepared, the chemical formulas of which are shown in Table 1 below.

[0054] [Table 1]

[0055] Each of these eight hexaferrite compositions is generally made according to the following procedure.

[0056] The metal source compounds used are BaCO3 (>99.5%), MgO (>99.5%), ZnO (>99.5%), TiO2 (>99.5%), and Fe2O3 (>99.2%).

[0057] The metal source compounds are mixed in a wet planetary mill in proportions to give the desired blend.

[0058] The mixture of metal source compounds is calcined by heating up to 1100° C. in air for a heating time of 4 hours.

[0059] The calcined ferrite material is then crushed and sieved through a 40# sieve. The sieved ferrite particles are then ground in a wet planetary mill to achieve a particle size of 0.5 to 10 microns.

[0060] The above fine ferrite particles are mixed with 0.5-5 weight percent (wt%) polyvinyl alcohol (PVA) and then granulated into granules by sieving through a 40# sieve.

[0061] The granules were mixed at 1MT / cm 2 The ferrite green bodies are compressed under a pressure of 0.05 MPa to form two different shapes of green bodies: toroids (OD = 7 mm, ID = 3 mm, thickness = 3-3.5 mm) for permeability and permittivity measurements, or disks (6 mm diameter) for magnetic hysteresis measurements.

[0062] The PVA 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 1150°C or 1250°C for 4 hours to obtain a polycrystalline ferrite composition. The oxygen gas flow rate is 0.5 L / min, the heating rate is 3°C / min, and the cooling rate is 3°C / min. Sintering at lower temperatures results in smaller particle sizes in the final ferrite composition compared to sintering at higher temperatures.

[0063] Magnetic hysteresis measurements are carried out using a Vibrating Sample Magnetometer (VSM) at room temperature with an applied magnetic field of 20 kOe.

[0064] Figure 2 shows the magnetic hysteresis loops determined for each of the eight ferrite compositions in Table 1. Table 2 below tabulates the saturation magnetization and coercivity for each of the ferrite compositions in Table 1. It has been observed that Zn dopants can maximize the saturation magnetization (~1300-1350 G), particularly at x = 1.0-1.2, while resulting in a minimum coercivity of 14 Oe. This means that Zn ions can actually tune the intrinsic properties of 18H ferrite, such as magnetization, anisotropy field, etc.

[0065] [Table 2]

[0066] The permeability / permittivity of ferrite samples is measured over a coaxial airline by a vector network analyzer (VNA) using the Nicholson-Ross-Ware (NRW) method over the frequency range of 0.1 to 10 GHz. Baker-Jarvis, J. et al., "Measuring the Permittivity and Permeability of Lossy Materials: Solids, Liquids, Metals, Building Materials, and Negative-index Materials," National Institute of Standards and Technology Technical Note 1536, p. 172 (February 2005). , U.S. Government Printing Office, 1999.

[0067] Figure 3 shows the Ba5Mg sintered at 1150°C. 2-x Zn x Ti3Fe 12 O 31(x=0 (#1-1), 0.25 (#2-1), 0.5 (#3-1), and 0.7 (#4-1)) samples, while Fig. 4 shows the magnetic permeability spectra of Ba5Mg sintered at 1250 °C. 2-x Zn x Ti3Fe 12 O 31 Figure 5 shows the permeability spectra of samples with x = 0 (#1-2), 0.25 (#2-2), 0.5 (#3-2), and 0.7 (#4-2). Tables 3 and 4 below tabulate the permeability, cutoff frequency, and Snoek's product from 1 to 3 GHz determined for each of these ferrite samples. Figure 5 and Table 5 show the permeability spectra of samples Ba5Mg sintered at 1200°C. 2-x Zn x Ti3Fe 12 O 31 (The magnetic permeability spectra and data summary for x = 0 (#1-3) are shown. The samples exhibit very low magnetic loss tangents (0.05-0.07), while the permeability remains higher than 2 or 4 over a wide frequency range from 1 to 4 GHz. Correspondingly, the specific loss (also called loss factor) ranges from 0.02 to 0.03. The magnetic loss, permeability, or cutoff frequency can be easily adjusted by changing the ratio of Mg and Zn ions to meet the needs of various applications.

[0068] [Table 3]

[0069] [Table 4]

[0070] [Table 5]

[0071] Described below are non-limiting aspects of the present disclosure.

[0072] Aspect 1: M5Me2Ti3Fe 12 O 31 (Wherein, M is Ba 2+ , Sr 2+ or a combination thereof; and Me is Mg 2+ , Zn 2+ , Cu 2+ , Co 2+ or a combination thereof); and having an average grain size of 1 micrometer to 100 micrometers, preferably 5 micrometers to 50 micrometers.

[0073] Aspect 2: (Ba 1-x Sr x )5Mg 2-y Me' y Ti3Fe 12-z O 31 (wherein Me' is Zn 2+ , Cu 2+ , Co 2+ or a combination thereof, wherein X=0 to 1.5, Y=0 to 1.8, and Z=-4 to +4.

[0074] Aspect 3: The polycrystalline ferrite composition of Aspect 2, wherein Y=0 to 1.0.

[0075] Embodiment 4: The polycrystalline ferrite composition of embodiment 2 or 3, wherein X=0.

[0076] Aspect 5: A magnetic permeability (μ) of at least 2 at a frequency of 1 to 4 GHz, preferably at least 5 at a frequency of 1 to 4 GHz; a magnetic loss tangent (tanδμ) of less than 0.05 at a frequency of 1 to 4 GHz, preferably less than 0.02 at a frequency of 1 to 4 GHz (more preferably, simultaneously maintaining a high magnetic permeability of at least 2 at said frequencies); a dielectric constant (ε) of at least 13 to 16 at a frequency of 1 to 4 GHz, preferably at least 13 to 15 at a frequency of 1 to 4 GHz; a dielectric loss tangent (tanδε) of less than 0.004 at a frequency of 1 to 4 GHz, preferably less than 0.003 at a frequency of 1 to 6 GHz; a magnetic loss coefficient (tanδμ / μ') of less than 0.02 at a frequency of 1 to 4 GHz or at a frequency of 2 to 6 GHz; a cutoff frequency (resonance frequency, f) of greater than 4 GHz, preferably greater than 6 GHz. r 5. The polycrystalline ferrite composition of any one of Aspects 1-4, having a Snoek product (where Snoek product = u' x fr) greater than 9 GHz, preferably greater than 12 GHz; or a combination of the foregoing properties.

[0077] Embodiment 6: The polycrystalline ferrite composition of any one of Embodiments 1-5, having easy in-plane (basal c-plane) magnetization.

[0078] Embodiment 7: The polycrystalline ferrite composition of any one of Embodiments 1-6, having an 18H structure.

[0079] Embodiment 8: A method for producing a polycrystalline ferrite composition, the method comprising the steps of calcining blended metal raw compounds for the polycrystalline ferrite composition of any one of Embodiments 1-7; reducing the particle size of the calcined raw compounds to obtain particles having an average particle size of 0.5 micrometers to 10 micrometers; granulating a mixture of the particles and a binder to obtain granules; compressing the granules into a green body; and sintering the green body to form the polycrystalline ferrite composition.

[0080] Aspect 9: The method of aspect 8, wherein the calcination is carried out at 900 to 1200° C. for 0.5 to 20 hours.

[0081] Embodiment 10: The method of embodiment 9, wherein the calcination is carried out in an atmosphere of air, nitrogen, oxygen, or a combination thereof.

[0082] Embodiment 11: The method of any one of Embodiments 8 to 10, wherein the sintering is carried out at 1000 to 1300° C. for 1 to 20 hours.

[0083] Embodiment 12: The method of any one of embodiments 8-11, wherein the sintering occurs in an atmosphere of air, nitrogen, oxygen, or a combination thereof.

[0084] Embodiment 13: The method of any one of embodiments 8 to 12, wherein the sintering is performed at a temperature heating rate of from 1° C. / min to 5° C. / min and / or a cooling rate of from 1° C. / min to 5° C. / min.

[0085] Embodiment 14: The method of any one of embodiments 8-13, wherein the particle size reduction step comprises crushing and / or grinding the calcined precursor compounds.

[0086] Embodiment 15: The method of any one of embodiments 8-14, further comprising sizing the particles.

[0087] Embodiment 16: The method of any one of embodiments 8-15, further comprising blending metal source compounds.

[0088] Embodiment 17: The method of any one of embodiments 8 to 16, wherein the binder is polyvinylpyrrolidone (PVP), poly(vinyl alcohol) (PVA), polyacrylamide (PAM), poly(acrylic acid) (PAA), polyethylene glycol (PEG), polyethylene oxide (PEO), cellulose acetate, starch, polypropylene carbonate, polyvinyl butyral (PVB), or a combination thereof; preferably, the binder is PVA, PVB, or a combination thereof.

[0089] Aspect 18: A composite (composite material) comprising: a polymer matrix; and the polycrystalline ferrite composition of any one of Aspects 1-7, wherein the ferrite composition has a particle size of 0.5-30 μm, preferably 1-10 μm.

[0090] Embodiment 19: The composite of embodiment 18, comprising 5 to 95 volume percent polycrystalline hexaferrite, based on the total volume of the composite.

[0091] Aspect 20: The polymer matrix is ​​selected from the group consisting of polycarbonate, polystyrene, polyphenylene ether, polyimide (e.g., polyetherimide), polybutadiene, polyacrylonitrile, poly((C1-12 alkyl)methacrylate) (e.g., polymethyl methacrylate (PMMA)), polyester (e.g., poly(ethylene terephthalate)), poly(butylene terephthalate), or polythioester), polyolefin (e.g., polypropylene (PP), high density polyethylene (HDPE), low density polyethylene (LDPE), or linear low density polyethylene (LLDPE)), polyamide (e.g., polyamideimide), polyarylate, polysulfone (e.g., polyarylsulfone or polysulfonamide), poly(phenylene sulfide), poly(phenylene oxide), polyether (e.g., poly(ether ketone) (PEK), poly(ether ether ketone) (PE EK), polyethersulfone (PES), polyacrylic, polyacetal, polybenzoxazole (e.g., polybenzothiazole or polybenzothiazinophenothiazine), polyoxadiazole, polypyrazinoquinoxaline, polypyromellitimide, polyquinoxaline, polybenzimidazole, polyoxindole, polyoxoisoindoline (e.g., polydioxoisoindoline), polytriazine, polypyridazine, polypiperazine, polypyridine, polypiperidine, polytriazole, polypyrazole, polypyrrolidine, polycarborane, polyoxabicyclononane, polydibenzofuran, polyphthalide, polyacetal, polyanhydride, vinyl polymer (e.g., poly(vinyl ether), poly(vinyl thioether), poly(vinyl alcohol), poly(vinyl ketone), poly(vinyl halides) (e.g., polyvinyl chloride). , poly(vinyl nitrile), or poly(vinyl ester)), polysulfonates, polysulfides, polyureas, polyphosphazenes, polysilazanes, polysiloxanes, fluoropolymers (e.g., poly(vinyl fluoride) (PVF20. The composite of any one of embodiments 18-19, wherein the polymer matrix comprises polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), polyethylene (PE), high density polyethylene (HDPE), low density polyethylene (LDPE), polymethyl methacrylate (PMMA), polyetheretherketone (PEEK), polyethersulfone (PES), or a combination thereof.

[0092] Aspect 21: A drive frequency of 1 GHz to 10 GHz; a magnetic permeability (μ) of at least 1.5 at frequencies of 1 to 10 GHz; a magnetic loss tangent (tanδ) of less than 0.02 at frequencies of 1 to 8 GHz. μ ); Dielectric constant (ε) of 5 to 6 at frequencies from 1 to 10 GHz; Dielectric loss tangent (tanδ) of less than 0.004 at frequencies from 1 to 10 GHz ε ); a magnetic loss coefficient (tanδ) of less than 0.01 or less than 0.008 at a frequency of 1 to 8 GHz or at a frequency of 2 to 10 GHz; μ / μ'); cutoff frequency (resonance frequency, f r 21. The conjugate of any one of embodiments 18 to 20, having:

[0093] Embodiment 22: A method of making the composite of any one of embodiments 18 to 21, comprising combining a polymer, a polycrystalline ferrite composition, optionally an optional solvent, and optionally an optional additive composition to form a composite, and optionally optionally removing the solvent from the composite.

[0094] Embodiment 23. The method of embodiment 22, further comprising molding the composite.

[0095] Embodiment 24: The method of embodiment 23, wherein forming the composite comprises compression molding, injection molding, reaction injection molding, extrusion, rolling, casting, or impregnating or laminating onto a reinforcing medium.

[0096] Embodiment 25: An article comprising the polycrystalline ferrite composition of any one of embodiments 1-7, or a polycrystalline ferrite composition produced by the method of any one of embodiments 8-17, or a composite of any one of embodiments 18-21, or a composite produced by the method of any one of embodiments 22-24.

[0097] Embodiment 26: The article of embodiment 25, wherein the article is an antenna, an inductor, a transformer, or an anti-electromagnetic interference material.

[0098] Embodiment 27: The article of embodiment 25 or 26, wherein the article is a microwave device.

[0099] In general, the above compositions, methods, and articles can alternatively comprise, consist of, or consist essentially of any component, step, or ingredient disclosed herein. The above compositions, methods, and articles can additionally or alternatively be formulated, performed, or manufactured to be devoid of, or substantially free of, any component, step, or ingredient that is not necessary to achieve the function or purpose of the invention.

[0100] The use of singular nouns does not denote a limitation of quantity, but rather denotes the presence of at least one of the referenced item. The term "or" means "and / or" unless the context clearly indicates otherwise. The endpoints of all ranges directed to the same component or property are inclusive of the endpoints, independently combinable, and include all intermediate points. The disclosure of a narrower range or more specific group in addition to a broader range does not disclaim that broader range or larger group. "Combinations thereof" is open-ended and includes one or more combinations of the referenced elements, optionally with one or more similar elements not referenced.

[0101] 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 belongs. The term "combination" is inclusive of blends, mixtures, alloys, reaction products, and the like. The permittivity and permeability used herein can be measured at a temperature of 23°C.

[0102] References throughout this specification to "aspects," "aspects," "embodiments," etc. mean that the particular element (e.g., feature, structure, step, or characteristic) described in connection with that aspect is included in at least one aspect described herein and may or may not be present in other aspects. Thus, although particular combinations of features have been described, it is understood that these combinations are for illustrative purposes only, and that any combination of these features may be employed, explicitly or equivalently, individually or in combination with any other feature disclosed herein, in any combination, and all features according to an aspect. All such combinations are contemplated herein and are considered to be within the scope of the disclosure.

[0103] While the disclosure has been described with reference to exemplary embodiments, those skilled in the art will recognize that various changes can be made and equivalents substituted for elements thereof without departing from the scope of the disclosure. In addition, many modifications can be made to adapt a particular situation or material to the teachings without departing from essential scope thereof. Therefore, the disclosure herein is not intended to be limited to the particular embodiment disclosed as the best or only mode contemplated for carrying out the invention, but the disclosure herein is intended to include all aspects falling within the scope of the appended claims.

Claims

1. M ５ Me ２ Till ３ Fe １２ Oh ３１ (In the formula, M is Ba ２＋ , Sr ２＋ or a combination thereof; and Me is Mg ２＋ , Zn ２＋ , Cu ２＋ , Co ２＋ , or a combination thereof) and having an average grain size of 1 micrometer to 100 micrometers.

2. (BL １－ｘ Sr ｘ ) ５ MM ２－ｙ Me' ｙ Ti ３ Fe １２－ｚ O ３１ (In the formula, Me' is Zn ２＋ , Cu ２＋ , Co ２＋ or a combination thereof, x=0 to 1.5; y=0 to 1.8, and z = -4 to +4) 2. The polycrystalline ferrite composition of claim 1 having the formula:

3. The polycrystalline ferrite composition according to claim 2, wherein y=0 to 1.

0.

4. 4. The polycrystalline ferrite composition according to claim 2 or 3, wherein x=0.

5. A magnetic permeability (μ) of at least 2 at frequencies between 1 and 4 GHz; A magnetic loss tangent (tanδ) of less than 0.05 at frequencies between 1 and 4 GHz μ ); a dielectric constant (ε) of at least 13-16 at frequencies between 1 and 4 GHz; A dielectric loss tangent (tanδ) of less than 0.004 at frequencies between 1 and 4 GHz ε ); A magnetic loss coefficient (tanδ) of less than 0.02 at frequencies of 1 to 4 GHz μ / μ′); A cutoff frequency greater than 4 GHz (resonant frequency, f ｒ ); Snoek product greater than 9 GHz (where Snoek product = u' x f ｒ is) or a combination of the aforementioned properties.

6. 6. The polycrystalline ferrite composition of claim 1, having easy in-plane (basal c-plane) magnetization and / or having an 18H structure.

7. calcining the mixed metal source compounds for the polycrystalline ferrite composition of any one of claims 1 to 6; reducing the particle size of the calcined precursor compound to obtain particles having an average particle size of 0.5 micrometers to 10 micrometers; granulating the mixture of the particles and a binder to obtain granules; compressing the granules into a green body; and sintering the green body to form a polycrystalline ferrite composition; A method for producing a polycrystalline ferrite composition, comprising:

8. The method according to claim 7, wherein the calcination is carried out at 900 to 1200°C for 0.5 to 20 hours.

9. 9. The method of claim 8, wherein the calcination is carried out in an atmosphere of air, nitrogen, oxygen, or a combination thereof.

10. The method according to any one of claims 7 to 9, wherein sintering is carried out at 1000 to 1300°C for 1 to 20 hours.

11. The method according to any one of claims 7 to 10, wherein the sintering is carried out in an atmosphere of air, nitrogen, oxygen, or a combination thereof.

12. The method according to any one of claims 7 to 11, wherein the sintering is carried out at a temperature heating rate of 1°C / min to 5°C / min and / or a cooling rate of 1°C / min to 5°C / min.

13. A process according to any one of claims 7 to 12, wherein the particle size reduction step comprises grinding and / or milling the calcined raw compound.

14. The method of any one of claims 7 to 13, further comprising sizing the particles.

15. The method of any one of claims 7 to 14, further comprising blending metal source compounds.

16. 16. The method of any one of claims 7 to 15, wherein the binder is polyvinylpyrrolidone (PVP), poly(vinyl alcohol) (PVA), polyacrylamide (PAM), poly(acrylic acid) (PAA), polyethylene glycol (PEG), polyethylene oxide (PEO), cellulose acetate, starch, polypropylene carbonate, polyvinyl butyral (PVB), or a combination thereof.

17. A composite comprising: a polymer matrix; and the polycrystalline ferrite composition of any one of claims 1 to 6, said ferrite composition having a grain size of 0.5 to 30 micrometers.

18. 18. The composite of claim 17, comprising 5 to 95 volume percent polycrystalline hexaferrite, based on the total volume of the composite.

19. 19. The composite of claim 17 or 18, wherein the polymer matrix comprises polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), polyethylene (PE), high density polyethylene (HDPE), low density polyethylene (LDPE), polymethyl methacrylate (PMMA), polyetheretherketone (PEEK), polyethersulfone (PES), or a combination thereof.

20. a driving frequency of 1 GHz to 10 GHz; a magnetic permeability (μ) of at least 1.5 at frequencies between 1 and 10 GHz; A magnetic loss tangent (tanδ) of less than 0.02 at frequencies between 1 and 8 GHz μ ); a dielectric constant (ε) of 5-6 at frequencies between 1 and 10 GHz; A dielectric loss tangent (tanδ) of less than 0.004 at frequencies between 1 and 10 GHz ε ); A magnetic loss coefficient (tanδ) of less than 0.01 or less than 0.008 at a frequency of 1 to 10 GHz. μ / μ′); A cutoff frequency (resonance frequency, f) greater than 8 GHz ｒ ); or 20. The composite of any one of claims 17 to 19, having a combination of the aforementioned properties.

21. combining the polymer, the polycrystalline ferrite composition, optionally optionally a solvent, and optionally optionally an additive composition to form a composite; and A method for producing a composite according to any one of claims 17 to 20, optionally including the step of removing the solvent from said composite.

22. The method of claim 21 further comprising molding the composite.

23. 23. The method of claim 22, wherein forming the composite comprises compression molding, injection molding, reaction injection molding, extrusion, rolling, casting, or impregnating or laminating onto a reinforcing medium.

24. An article comprising the polycrystalline ferrite composition according to any one of claims 1 to 6, or a polycrystalline ferrite composition produced by the manufacturing method according to any one of claims 7 to 16, or the composite according to any one of claims 17 to 20, or a composite produced by the manufacturing method according to any one of claims 21 to 23.

25. 25. The article of claim 24, wherein the article is an antenna, an inductor, a transformer, or an anti-electromagnetic interference material.

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