Patent Publication Number: US-2021179442-A1

Title: Bismuth ruthenium m-type hexaferrite

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application claims the benefit of U.S. Provisional Patent Application Ser. No. 62/904,903 filed Sep. 24, 2019. The related application is incorporated herein in its entirety by reference. 
    
    
     BACKGROUND 
     Improved performance and miniaturization are needed to meet the ever-increasing demands of devices used in ultrahigh frequency (UHF), L-band, and S-band applications, which are of particular interest in a variety of commercial and defense related industries. As an important component in radar and modern wireless communication systems, antenna elements with compact size are constantly being developed. It has been challenging, however, to develop ferrite materials for use in such high frequency applications as most ferrite materials exhibit relatively high magnetic loss at high frequencies. In general, hexagonal ferrites, or hexaferrites, are a type of iron-oxide ceramic compound that has a hexagonal crystal structure and exhibits magnetic properties. Several types of families of hexaferrites are known, including Z-type ferrites, Ba 3 Me 2 Fe 24 O 41 , and Y-type ferrites, Ba 2 Me 2 Fe 12 O 22 , where Me can be a small 2+ cation such as Co, Ni, or Zn, and Sr can be substituted for Ba. Other hexaferrite types include M-type ferrites ((Ba,Sr)Fe 12 O 19 ), W-type ferrites ((Ba,Sr)Me 2 Fe 16 O 27 ), X-type ferrites ((Ba,Sr) 2 Me 2 Fe 28 O 46 ), and U-type ferrites ((Ba,Sr) 4 Me 2 Fe 36 O 60 ). 
     Despite these improvements in ferrite composites, their use in high frequency and microwave devices is limited as these substitutions also result in an increase in the magnetic loss. Improved ferrite compositions are therefore desired. 
     BRIEF SUMMARY 
     Disclosed herein is a BiRuCo-M-type phase ferrite. 
     In an aspect, a ferrite composition comprises a BiRuCo-M-type ferrite having the formula Me 1-x Bi x Co y Ru z Fe 12-t O 19 , wherein Me is at least one of Sr, Pb, or Ba; x is 0.01 to 0.5; y is 0.1 to 2; z is 0 to 4, and t is 0 to 4; wherein the Co can be at least partially replaced by at least one of Zn, Cu, or Mg by an amount of less than y, and the Ru can be at least partially replaced by at least one of Ti, Sn, or Zr, where the substitution amount is not more than z or is less than z. 
     In another aspect, an article comprises at least one of the ferrite composition or a ferrite composite comprising the ferrite composition. 
     In yet another aspect, a method of making the ferrite composition comprises mixing ferrite precursor compounds comprising Me, Fe, Bi, Co, and Ru; and sintering the ferrite precursor compounds in an oxygen atmosphere to form the BiRuCo-M-type ferrite. 
     The above described and other features are exemplified by the following FIGURE, detailed description, and claims. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWING 
       The following FIGURE is an exemplary embodiment that is provided to illustrate the present disclosure. The FIGURE is illustrative of the example, which is not intended to limit devices made in accordance with the disclosure to the materials, conditions, or process parameters set forth herein. 
         FIG. 1  is a graphical illustration of the permeability and magnetic loss tangent with frequency for Example 1 and Example 2. 
     
    
    
     DETAILED DESCRIPTION 
     It was discovered that substituting at least a portion of the metal ion in an M-type hexaferrite with ruthenium and bismuth could result in a BiRuCo-M-type ferrite with improved properties. Specifically, the BiRuCo-M-type ferrite that can have the general formula: 
       Me 1-x Bi x Co y Ru z Fe 12-t O 19    
     wherein Me is at least one of Sr, Pb, or Ba; x is 0.01 to 0.5; y is 0.1 to 2; z is 0 to 4, t is 0 to 4, the Co can be at least partially replaced by at least one of Zn, Cu, or Mg by an amount of less than y, and the Ru can be at least partially replaced by at least one of Ti, Sn, or Zr, where the substitution amount is not more than z or is less than z. Me can be at least Ba. 
     The BiRuCo-M-type ferrite can have a planar easy magnetization (c-plane). The BiRuCo-M-type ferrite can have at least one of a high permeability, high operating frequency, or a low magnetic loss, making it suitable for use as an antenna or an inductor at S-L band frequency. The BiRuCo-M-type ferrite can have a permeability of greater than or equal to 2.5, or greater than or equal to 3, or 2.5 to 4 at a frequency of 1 to 2 gigahertz, or at 1 to 4 gigahertz in the form of a solid ceramic. The BiRuCo-M-type ferrite can have a magnetic loss tangent tan δ μ  of less than or equal to 0.2, less than or equal to 0.5, or less than or equal to 0.05, or 0.01 to 0.4 at a frequency of 1 to 2 gigahertz in the form of a solid ceramic. The BiRuCo-M-type ferrite can have a permittivity of 8 to 12, or 6 to 11 at a frequency of 1 to 2 gigahertz in the form of a solid ceramic. The BiRuCo-M-type ferrite can have a dielectric loss tangent tank of less than or equal to 0.02, less than or equal to 0.008, or 0.001 to 0.2 at a frequency of 1 to 2 gigahertz in the form of a solid ceramic. The BiRuCo-M-type ferrite can have an operating frequency of 0.1 to 4 gigahertz, or 0.5 to 2 gigahertz, or 1 to 2 gigahertz, in the form of a solid ceramic. 
     The BiRuCo-M-type ferrite can have at least one of a low dielectric loss tangent tank or a magnetic loss tangent tan N within the ultrahigh frequency range. For example, the BiRuCo-M-type ferrite can have at least one of a dielectric loss tangent tank of less than or equal to 0.01, or less than or equal to 0.008, or 0.006 to 0.01 or a magnetic loss tangent tan N of less than or equal to 0.12, or less than or equal to 0.08, or 0.05 to 0.12 at a frequency of 1 to 2 gigahertz, in the form of a solid ceramic. 
     As used herein, magnetic and dielectric properties are measured in coaxial airline by vector network analyzer (VNA) using the Nicholson-Ross-Weir (NRW) method and the permeability and permittivity values are the relative permeability and the relative permittivity, respectively. 
     The BiRuCo-M-type ferrite can be prepared using any suitable method. Generally, the BiRuCo-M-type ferrite can be formed by first forming a mixture comprising the precursor compounds including oxides of at least Me, Bi, Co, Ru, and Fe. For example, the mixture can comprise at least MeCO 3 , Bi 2 O 3 , Co 3 O 4 , RuO 2 , and Fe 2 O 3 . The mixture can comprise 5 to 20 weight percent of MeCO 3  based on the total weight of the precursor compounds. The mixture can comprise 0.01 to 20 weight percent, or 5 to 20 weight percent of Bi 2 O 3  based on the total weight of the precursor compounds. The mixture can comprise 1 to 15 weight percent of Co 3 O 4  based on the total weight of the precursor compounds. The mixture can comprise 0.1 to 10 weight percent of RuO 2  based on the total weight of the precursor compounds. The mixture can comprise 50 to 80 weight percent of Fe 2 O 3  based on the total weight of the precursor compounds. The mixture can further comprise an oxide of at least one of Zn, Mg, Ti, Zr, Sn, or Cu. 
     The mixture can be calcined in air to form a calcined ferrite comprising an M-type ferrite. The calcining can occur at a calcination temperature of 800 to 1,300 degrees Celsius (° C.). The calcining can occur for a calcination time of 0.5 to 20 hours, 1 to 10 hours, or 2 to 5 hours. It is noted that the calcination step is optional, and the only heating step can be the sintering. 
     The calcined ferrite can be crushed and optionally sieved to form particulates. The sieving can comprise sieving through a number 10 to 100 mesh screen. Coarse particles can be further ground to reduce the particle size. The particulates can have a median D50 particle size by volume of 0.5 to 50 micrometers, or 0.5 to 10 micrometers. The particle size can be determined using Horiba LA-910 laser light scattering PSD analyzer or as determined in accordance with ASTM D4464-15. The calcined ferrite can be mixed with a binder. The binder can comprise at least one of poly(vinyl alcohol), poly(vinyl butyral), methyl cellulose, poly(ethylene glycol), or poly(alkylene carbonate). The binder can be present in an amount of 8 to 12 weight percent based on the total amount of the calcined ferrite plus the binder. The binder can facilitate shaping of the calcined ferrite and can fully burn off during sintering. The bound calcined ferrite can have a median D50 particle size by volume of 10 to 300 micrometers, or 50 to 300 micrometers. 
     The calcined ferrite can be optionally shaped and sintered to form the BiRuCo-M-type ferrite. The method of shaping is not limited and can comprise at least one of uniaxial compression, isostatic pressing, casting, pressing, or the like. The pressing can occur at a pressure of 0.5 to 2 metric tons per centimeter squared. The sintering can occur at a sintering temperature of 1,000 to 1,300° C., or 1,200 to 1,250° C. The ramping temperature up to and down from the sintering temperature can each independently occur at a ramp rate of 1 to 5° C. per minute. The sintering can occur for a sintering time of 1 to 20 hours, or 5 to 12 hours. The sintering can be performed in an oxygen environment to help reduce the dielectric loss. Oxygen can be introduced to the sintering chamber at a flow rate of 0.1 to 10 liters per minute. The sintered BiRuCo-M-type ferrite can be finished in any desired manner, for example, by cutting or polishing, depending on the application. 
     Prior to the sintering, an additional amount of bismuth oxide can be added to the calcined ferrite. The bismuth oxide can be added in an amount of 0.01 to 5 weight percent based on the total weight of the calcined ferrite. Bi 2 O 3  can be added into a starting mixture or to the calcined ferrite powder, depending upon the desired distribution of Bi ions. Bi ions can be located in the crystalline lattice or can be at the grain boundaries. The addition of an additional amount of Bi 2 O 3 , which can be present at grain boundaries of the M-type ferrite phase, can aid in achieving a composition that has equal or substantially equal values of permeability and permittivity while retaining low magnetic and dielectric loss tangents. 
     The BiRuCo-M-type ferrite can have an average grain size of 1 to 100 micrometers, or 5 to 50 micrometers. 
     The BiRuCo-M-type ferrite can be a bulk ceramic or can be present in a composite, for example, comprising the BiRuCo-M-type ferrite and a polymer. The polymer can comprise a thermoplastic or a thermoset. As used herein, the term “thermoplastic” refers to a material that is plastic or deformable, melts to a liquid when heated, and freezes to a brittle, glassy state when cooled sufficiently. Examples of thermoplastic polymers that can be used include cyclic olefin polymers (including polynorbornenes and copolymers containing norbornenyl units, for example, copolymers of a cyclic polymer such as norbornene and an acyclic olefin such as ethylene or propylene), fluoropolymers (for example, polyvinyl fluoride (PVF), polyvinylidene fluoride (PVDF), fluorinated ethylene-propylene (FEP), polytetrafluoroethylene (PTFE), poly(ethylene-tetrafluoroethylene (PETFE), or perfluoroalkoxy (PFA)), polyacetals (for example, polyoxyethylene and polyoxymethylene), poly(C 1-6  alkyl)acrylates, polyacrylamides (including unsubstituted and mono-N- or di-N—(C 1-8  alkyl)acrylamides), polyacrylonitriles, polyamides (for example, aliphatic polyamides, polyphthalamides, or polyaramides), polyamideimides, polyanhydrides, polyarylene ethers (for example, polyphenylene ethers), polyarylene ether ketones (for example, polyether ether ketones (PEEK) and polyether ketone ketones (PEKK)), polyarylene ketones, polyarylene sulfides (for example, polyphenylene sulfides (PPS)), polyarylene sulfones (for example, polyethersulfones (PES), polyphenylene sulfones (PPS), and the like), polybenzothiazoles, polybenzoxazoles, polybenzimidazoles, polycarbonates (including homopolycarbonates or polycarbonate copolymers such as polycarbonate-siloxanes, polycarbonate-esters, or polycarbonate-ester-siloxanes), polyesters (for example, polyethylene terephthalates, polybutylene terephthalates, polyarylates, or polyester copolymers such as polyester-ethers), polyetherimides (for example, copolymers such as polyetherimide-siloxane copolymers), polyimides (for example, copolymers such as polyimide-siloxane copolymers), poly(C 1-6  alkyl)methacrylates, polyalkylacrylamides (for example, unsubstituted and mono-N- or di-N—(C 1-8  alkyl)acrylamides), polyolefins (for example, polyethylenes, such ashigh density polyethylene (HDPE), low density polyethylene (LDPE), and linear low density polyethylene (LLDPE), polypropylenes, and their halogenated derivatives (such as polytetrafluoroethylenes), and their copolymers, for example, ethylene-alpha-olefin copolymers), polyoxadiazoles, polyoxymethylenes, polyphthalides, polysilazanes, polysiloxanes (silicones), polystyrenes (for example, copolymers such as acrylonitrile-butadiene-styrene (ABS) or methyl methacrylate-butadiene-styrene (MBS)), polysulfides, polysulfonamides, polysulfonates, polysulfones, polythioesters, polytriazines, polyureas, polyurethanes, vinyl polymers (for example, polyvinyl alcohols, polyvinyl esters, polyvinyl ethers, polyvinyl halides (for example, polyvinyl chloride), polyvinyl ketones, polyvinyl nitriles, or polyvinyl thioethers), a paraffin wax, or the like. A combination comprising at least one of the foregoing thermoplastic polymers can be used. 
     Thermoset polymers are derived from thermosetting monomers or prepolymers (resins) that can irreversibly harden and become insoluble with polymerization or cure, which can be induced by heat or exposure to radiation (e.g., ultraviolet light, visible light, infrared light, or electron beam (e-beam) radiation). Thermoset polymers include alkyds, bismaleimide polymers, bismaleimide triazine polymers, cyanate ester polymers, benzocyclobutene polymers, benzoxazine polymers, diallyl phthalate polymers, epoxies, hydroxymethylfuran polymers, melamine-formaldehyde polymers, phenolics (including phenol-formaldehyde polymers such as novolacs and resoles), benzoxazines, polydienes such as polybutadienes (including 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, such as unsaturated polyesters or polyimides), or the like. The prepolymers can be polymerized, copolymerized, or crosslinked, e.g., with a reactive monomer such as styrene, alpha-methylstyrene, vinyltoluene, chlorostyrene, acrylic acid, (meth)acrylic acid, a (C 1-6  alkyl)acrylate, a (C 1-6  alkyl) methacrylate, acrylonitrile, vinyl acetate, allyl acetate, triallyl cyanurate, triallyl isocyanurate, or acrylamide. 
     The BiRuCo-M-type ferrite can be mixed with a polymer to form the composite. The mixing can comprise mixing at a temperature of a melting point of the polymer. The mixing can comprise mixing a polymer precursor with the BiRu-Co 2 M ferrite and reacting the polymer precursor to form the polymer. Methods of forming the composite are not limited and can comprise injection molding, reaction injection molding, laminating, extruding, compression molding, calendering, casting, and the like. The composite can be free of a void space. 
     The BiRuCo-M-type ferrite can be surface-treated (also referred to herein as coated) to aid dispersion into the polymer or polymer precursor, for example, with at least one of a surfactant (such as oleylamine oleic acid), an inorganic material (such as SiO 2 , Al 2 O 3 , or MgO), a silane, a titanate, or a zirconate. 
     The coating can comprise at least one of a silane coating, a titanate coating, or a zirconate coating. The coating can comprise at least one of phenyltrimethoxysilane, p-chloromethylphenyltrimethoxy silane, aminoethylaminotrimethoxy silane, aminoethylaminopropyltrimethoxy silane, phenyltriethoxysilane, 3,3,3-trifluoropropyl trimethoxysilane, (tridecafluoro-1,1,2,2-tetrahydrodecyl)-1-triethoxysilane, neopentyl(diallyl)oxytrineodecanoyl titanate, neopentyl(diallyl)oxytri(dioctyl)phosphate titanate, neopentyl(diallyl)oxytri(dioctyl)pyrophosphate zirconate, or neopentyl(diallyl) oxytri(N-ethylenediamino)ethyl zirconate. The coating can comprise a silane coating comprising at least one of an aromatic silane such as phenyltrimethoxysilane or a fluorinated aliphatic alkoxy silane such as (tridecafluoro-1,1,2,2-tetrahydrooctyl)triethoxy silane. 
     An article can comprise the BiRuCo-M-type ferrite. The article can be an antenna or an inductor core. The article can be for use in the frequency range of 0.1 to 4 gigahertz, or 0.5 to 2 gigahertz. The article can be used for a variety of devices operable within the ultrahigh frequency range, such as a high frequency or microwave antenna, filter, inductor, circulator, or phase shifter. The article can be operable at frequencies greater than or equal to 0.1 GHz, or at frequencies greater than or equal to 0.3 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. 
     A ferrite composition comprising a BiRuCo-M-type ferrite can have the formula Me 1-x Bi x Co y Ru z Fe 12-t O 19 . Me can comprise at least one of Sr, Pb, or Ba. Me can comprise at least Ba. x can be 0.01 to 0.5, or 0.01 to 0.5. y can be 0.1 to 2, or 1 to 2. z can be 0 to 4. t can be 0 to 4. The Co can be at least partially replaced by at least one of Zn, Cu, or Mg by an amount of less than y. The Ru can be at least partially replaced by at least one of Ti, Sn, or Zr, where the substitution amount is not more than z or is less than z. The BiRuCo-M-type ferrite can have the formula Ba 1-x Bi x Co y Ru z Fe 12-t O 19 . 
     The ferrite composition can have a permeability of greater than or equal to 2.5, or greater than or equal to 3, or 2.5 to 4 at a frequency of 1 to 2 gigahertz in the form of a solid ceramic. The ferrite composition can have a permittivity of 8 to 12, or 6 to 11 at a frequency of 1 to 2 gigahertz in the form of a solid ceramic. The ferrite composition can have a magnetic loss tangent tan δ μ  of less than or equal to 0.2, less than or equal to 0.5, or less than or equal to 0.05, or 0.01 to 0.4 at a frequency of 1 to 2 gigahertz in the form of a solid ceramic. The ferrite composition can have a dielectric loss tangent tank of less than or equal to 0.02, less than or equal to 0.008, or 0.001 to 0.2 at a frequency of 1 to 2 gigahertz in the form of a solid ceramic. A composite can comprise the ferrite composition and a polymer. An article can comprise the ferrite composition. An article can comprise the ferrite composite. The article can be an antenna, filter, inductor, circulator, or phase shifter. The article can be a microwave antenna. The antenna can be operable at a frequency of greater than or equal to 0.1 gigahertz, or greater than or equal to 0.3 gigahertz, or 0.1 to 4 gigahertz. 
     A method of making a ferrite composition can comprise mixing ferrite precursor compounds comprising Me, Fe, Bi, Co, and Ru; and sintering the ferrite precursor compounds in an oxygen atmosphere to form the BiRuCo-M-type ferrite. The ferrite precursor compounds can comprise MeCO 3 , Bi 2 O 3 , Co 3 O 4 , RuO 2 , and Fe 2 O 3 . The ferrite precursor compounds can comprise 5 to 20 weight percent of MeCO 3 , 0.01 to 20 weight percent of Bi 2 O 3 , 1 to 15 weight percent of Co 3 O 4 , 0.1 to 10 weight percent of RuO 2 , and 50 to 80 weight percent of Fe 2 O 3 ; all based on the total weight of the precursor compounds. The sintering can occur at a sintering temperature of 1,000 to 1,300° C., or 1,200 to 1,250° C. for a sintering time of 1 to 20 hours, or 5 to 12 hours. The method can further comprise calcining the ferrite precursor compounds in air prior to the sintering. The method can further comprise mixing the ferrite precursor compounds with a binder prior to the sintering. The method can further comprise forming the ferrite precursor compounds prior to the sintering. 
     The following examples are provided to illustrate the present disclosure. The examples are merely illustrative and are not intended to limit devices made in accordance with the disclosure to the materials, conditions, or process parameters set forth therein. 
     EXAMPLES 
     In the examples, the magnetic permeability of the resulting ferrite samples was measured in coaxial airline by vector network analyzer (VNA) using the Nicholson-Ross-Weir (NRW) method over a frequency of 0.1 to 10 GHz. 
     The particle sizes were determined using Horiba LA-910 laser light scattering PSD analyzer or as determined in accordance with ASTM D4464-15. The reported particle size is the median D50 particle size by volume. 
     Examples 1 and 2: Effect of Bismuth on the BiRuCo-M-Type Phase Ferrite 
     Two samples of the RuCo-M-type phase ferrite with and without bismuth were formed by mixing appropriate amounts of BaCO 3 , Bi 2 O 3 , Co 3 O 4 , RuO 2 , and Fe 2 O 3  in a wet planetary mill to form a mixture. The mixtures were calcined to a calcination temperature of 1,200° C. for a soak time of 4 hours in air. The calcined ferrite was crushed and sieved through a 40 mesh screen. The coarse particles were ground to form particulates having a median D50 particle size by volume of 0.5 to 10 micrometers in a wet planetary mill. A granulate mixture was formed by mixing the particulates with 0.5 to 5 weight percent of poly(vinyl alcohol) based the total amount of the granulate mixture. The granulate mixture was then compressed to form toroid granules having an outer diameter of 7 millimeters, an inner diameter of 3 millimeters, and a thickness of 3 to 3.5 millimeters at a pressure of 1 metric tons per centimeter squared. The toroid granules were sintered at a sintering temperature of 1,200° C. for 10 hours in atmosphere of oxygen by flowing oxygen gas at a rate of 0.5 liters per minute, using a ramp rate: 3° C. per minute and a cooling rate of −3° C. per minute. The RuCo-M-type phase ferrites with and without bismuth had formulae BaCo 1.2 Ru 0.2 Fe 10.93 O 19  and Ba 0.95 Bi 0.05 Co 1.2 Ru 0.2 Fe 10.93 O 19 , respectively. 
     The permeability (solid lines) and the magnetic loss tangent (dashed lines) are shown in  FIG. 1  as a function of frequency and specific values of the different compositions are shown in Table 1. 
     
       
         
           
               
               
               
               
             
               
                   
                 TABLE 1 
               
               
                   
                   
               
               
                   
                 Ferrite Sample 
                 1 
                 2 
               
               
                   
                   
               
             
            
               
                   
                 Bismuth 
                 N 
                 Y 
               
               
                   
                 μ′ at 1 GHz 
                 3.37 
                 2.90 
               
               
                   
                 μ′ at 1.6 GHz 
                 3.31 
                 2.98 
               
               
                   
                 μ′ at 2 GHz 
                 3.21 
                 3.02 
               
               
                   
                 tanδ μ  at 1 GHz 
                 0.10 
                 0.05 
               
               
                   
                 tanδ μ  at 1.6 
                 0.20 
                 0.09 
               
               
                   
                 GHz 
                   
                   
               
               
                   
                 tanδ μ  at 2 GHz 
                 0.25 
                 0.16 
               
               
                   
                 ε′ at 1 GHz 
                 11.3 
                 10.9 
               
               
                   
                 ε′ at 1.6 GHz 
                 11.2 
                 10.8 
               
               
                   
                 ε′ at 2 GHz 
                 11.3 
                 10.8 
               
               
                   
                 tanδ ε  at 1 GHz 
                 0.052 
                 0.017 
               
               
                   
                 tanδ ε  at 1.6 
                 0.040 
                 0.013 
               
               
                   
                 GHz 
                   
                   
               
               
                   
                 tanδ ε  at 2 GHz 
                 0.040 
                 0.015 
               
               
                   
                   
               
            
           
         
       
     
     The results show that incorporating an amount of bismuth in the ruthenium ferrite, results in a significant decrease in the magnetic loss tangent, while still maintaining a permeability, μ′, of greater than or equal to 2.5 from 1 to 2 gigahertz. 
     Set forth below are non-limiting aspects of the present disclosure. 
     Aspect 1: A ferrite composition comprising a BiRuCo-M-type ferrite having the formula Me 1-x Bi x Co y Ru z Fe 12-t O 19 , wherein Me is at least one of Sr, Pb, or Ba; x is 0.01 to 0.5; y is 0.1 to 2; z is 0 to 4, and t is 0 to 4; wherein the Co can be at least partially replaced by at least one of Zn, Cu, or Mg by an amount of less than y, and the Ru can be at least partially replaced by at least one of Ti, Sn, or Zr, where the substitution amount is not more than z or is less than z. 
     Aspect 2: The ferrite composition of aspect 1, wherein y is 1 to 2. 
     Aspect 3: The ferrite composition of any one or more of the preceding aspects, wherein Me is at least Ba. 
     Aspect 4: The ferrite composition of any one or more of the preceding aspects, wherein x is 0.01 to 0.5. 
     Aspect 5: The ferrite composition of any one or more of the preceding aspects, wherein the ferrite composition has a permeability of greater than or equal to 2.5, or greater than or equal to 3, or 2.5 to 4 at a frequency of 1 to 2 gigahertz in the form of a solid ceramic. 
     Aspect 6: The ferrite composition of any one or more of the preceding aspects, wherein the ferrite composition has a permittivity of 8 to 12, or 6 to 11 at a frequency of 1 to 2 gigahertz in the form of a solid ceramic. 
     Aspect 7: The ferrite composition of any one or more of the preceding aspects, wherein the ferrite composition has a magnetic loss tangent tan N of less than or equal to 0.2, less than or equal to 0.5, or less than or equal to 0.05, or 0.01 to 0.4 at a frequency of 1 to 2 gigahertz in the form of a solid ceramic. 
     Aspect 8: The ferrite composition of any one or more of the preceding aspects, wherein the ferrite composition has a dielectric loss tangent tank of less than or equal to 0.02, less than or equal to 0.008, or 0.001 to 0.2 at a frequency of 1 to 2 gigahertz in the form of a solid ceramic. 
     Aspect 9: A composite comprising the ferrite composition of any one or more of the preceding aspects and a polymer. 
     Aspect 10: An article comprising the ferrite composition of any one or more of Aspects 1 to 9 or the composite of Aspect 9. 
     Aspect 11: The article of aspect 10, wherein the article is an antenna, filter, inductor, circulator, or phase shifter. 
     Aspect 12: The article of any one or more of Aspects 10 to 11, wherein the article is a microwave antenna. 
     Aspect 13: The article of any one or more of Aspects 10 to 12, wherein the article is an antenna operable at a frequency of greater than or equal to 0.1 gigahertz, or greater than or equal to 0.3 gigahertz, or 0.1 to 4 gigahertz. 
     Aspect 14: A method of making a ferrite composition, for example, of any one or more of the preceding aspects comprising: mixing ferrite precursor compounds comprising Me, Fe, Bi, Co, and Ru; and sintering the ferrite precursor compounds in an oxygen atmosphere to form the BiRuCo-M-type ferrite. 
     Aspect 15: The method of Aspect 14, wherein the ferrite precursor compounds comprise MeCO 3 , Bi 2 O 3 , Co 3 O 4 , RuO 2 , and Fe 2 O 3 . 
     Aspect 16: The method of Aspect 15, wherein the ferrite precursor compounds comprise 5 to 20 weight percent of MeCO 3 , 0.01 to 20 weight percent of Bi 2 O 3 , 1 to 15 weight percent of Co 3 O 4 , 0.1 to 10 weight percent of RuO 2 , and 50 to 80 weight percent of Fe 2 O 3 ; all based on the total weight of the precursor compounds. 
     Aspect 17: The method of any one or more of Aspects 14 to 16, wherein the sintering occurs at a sintering temperature of 1,000 to 1,300° C., or 1,200 to 1,250° C. for a sintering time of 1 to 20 hours, or 5 to 12 hours. 
     Aspect 18: The method of any one or more of Aspects 14 to 17, further comprising calcining the ferrite precursor compounds in air prior to the sintering. 
     Aspect 19: The method of any one or more of Aspects 14 to 18, further comprising mixing the ferrite precursor compounds with a binder prior to the sintering. 
     Aspect 20: The method of any one or more of Aspects 14 to 19, further comprising forming the ferrite precursor compounds prior to the sintering. 
     Aspect 21: The ferrite composition or method of any one or more of the preceding aspects, wherein the Co is at least partially replaced by Zn, Cu, or Mg by an amount of less than y. 
     Aspect 22: The ferrite composition or method of any one or more of the preceding aspects, wherein the Ru is at least partially replaced by at least one of Ti, Sn, or Zr, where the substitution amount is not more than z or is less than z. 
     Aspect 23: The ferrite composition or method of any one or more of the preceding aspects, wherein the Ru is not at least partially replaced and/or the Co is not at least partially replaced. 
     The compositions, methods, and articles can alternatively comprise, consist of, or consist essentially of, any appropriate materials, steps, or components herein disclosed. The compositions, methods, and articles can additionally, or alternatively, be formulated so as to be devoid, or substantially free, of any materials (or species), steps, or components, that are otherwise not necessary to the achievement of the function or objectives of the compositions, methods, and articles. 
     As used herein, “a,” “an,” “the,” and “at least one” do not denote a limitation of quantity, and are intended to cover both the singular and plural, unless the context clearly indicates otherwise. For example, “an element” has the same meaning as “at least one element,” unless the context clearly indicates otherwise. The term “at least one of” means that the list is inclusive of each element individually, as well as combinations of two or more elements of the list, and combinations of at least one element of the list with like elements not named. Also, the term “combination” is inclusive of blends, mixtures, alloys, reaction products, and the like. The term “or” means “and/or” unless clearly indicated otherwise by context. Reference throughout the specification to “an aspect”, “an embodiment”, “another embodiment”, “some embodiments”, and so forth, means that a particular element (e.g., feature, structure, step, or characteristic) described in connection with the embodiment is included in at least one embodiment described herein, and may or may not be present in other embodiments. In addition, it is to be understood that the described elements may be combined in any suitable manner in the various embodiments. 
     Unless specified to the contrary herein, all test standards are the most recent standard in effect as of the filing date of this application, or, if priority is claimed, the filing date of the earliest priority application in which the test standard appears. 
     The endpoints of all ranges directed to the same component or property are inclusive of the endpoints, are independently combinable, and include all intermediate points and ranges. For example, ranges of “up to 25 wt %, or 5 to 20 wt %” is inclusive of the endpoints and all intermediate values of the ranges of “5 to 25 wt %,” such as 10 to 23 wt %, etc. 
     Unless defined otherwise, technical and scientific terms used herein have the same meaning as is commonly understood by one of skill in the art to which this disclosure belongs. 
     All cited patents, patent applications, and other references are incorporated herein by reference in their entirety. However, if a term in the present application contradicts or conflicts with a term in the incorporated reference, the term from the present application takes precedence over the conflicting term from the incorporated reference. 
     While particular embodiments have been described, alternatives, modifications, variations, improvements, and substantial equivalents that are or may be presently unforeseen may arise to applicants or others skilled in the art. Accordingly, the appended claims as filed and as they may be amended are intended to embrace all such alternatives, modifications variations, improvements, and substantial equivalents.