58 results about "Hexagonal ferrite" patented technology

The magnetic tape includes a non-magnetic support, and a magnetic layer containing a ferromagnetic powder. The ferromagnetic powder is a hexagonal ferrite powder, tilt cos θ of the hexagonal ferrite powder with respect to a surface of the magnetic layer, which is acquired by cross-sectional observation performed using a scanning transmission electron microscope, is 0.85 or more and 1.00 or less, and standard deviation σ of the cos θ in a width direction of the surface of the magnetic layer is 0.03 or less.

The invention discloses a Y-type hexagonal ferrite high-quality single crystal growth method, and belongs to the technical field of ferrite ceramic materials. The chemical expression of the Y-type hexagonal ferrite is Sr < 2 > Zn < 2-x > Ni < x > Fe < 12 > O < 22 >, wherein x is equal to 0 to 2; the method comprises the following steps: weighing SrCO3, ZnO, NiO and Fe2O3 according to the composition of the Y-type hexagonal ferrite, mixing the SrCO3, ZnO, NiO and Fe2O3 with a fluxing agent, and grinding to obtain precursor powder; carrying out temperature-changing staged sintering on the precursor powder, and carrying out 40-stage sintering in total; and after the staged sintering is finished, extracting a sintered product to obtain the Y-type hexagonal ferrite. The Y-type hexagonal ferrite high-quality single crystal material prepared by a fluxing agent method provides a material basis for further research on anisotropy of magnetism and ferroelectric properties of Y-type hexagonal ferrite and other potential application values.

A ferrite powder comprising, as a main component compound, a magnetoplumbite-type hexagonal ferrite having a composition represented by the formula Sr(FexAlyZrz)12O19+δ (where x, y, z, and δ satisfy 0.400≤x<1.000, 0.030≤y≤0.350, 0.001≤z≤0.040, 0.750≤x+y+z<1.000, and -5.00≤δ≤-0.200), and having a volume resistance of 1.0×109 Ω·cm or less. A ferrite resin composite material, ferrite resin composite, and electromagnetic wave absorber containing said ferrite powder.

A hexagonal ferrite magnetic powder is significantly more useful for achieving simultaneously both the enhancement of the recording density and the enhancement of the SNR of a magnetic recording medium. The hexagonal ferrite magnetic powder contains Bi at a Bi / Fe molar ratio in a range of 0.035 or less, has a saturation magnetization σs of 42.0 Am2 / kg or more and a Dx volume calculated based on the crystallite diameters of 1,800 nm3 or less. A method for producing hexagonal ferrite magnetic powder includes a step of performing a treatment of immersing hexagonal ferrite magnetic powder containing Bi in a solution having dissolved therein a compound X that forms a complex with Bi, so as to elute a part of Bi existing in the hexagonal ferrite magnetic powder into the solution.

Provided is an electromagnetic wave absorption sheet that has high electromagnetic wave absorption characteristics with respect to a wide frequency band of electromagnetic waves, and that has a small overall sheet thickness. This electromagnetic wave absorption sheet comprises: a magnetic layer 1 including a magnetic iron oxide 1a, a dielectric constant adjustment agent 1b, and a binder 1c; and an electromagnetic wave reflection layer 2. The magnetic iron oxide is hexagonal ferrite. The input impedance Z of the entire electromagnetic wave absorption sheet is 260 Ω or more and 610 Ω or less. A reflection attenuation curve representing the reflection attenuation characteristics of the sheet has a maximum absorption peak and at least one of a shoulder peak and a second absorption peak smaller than the maximum absorption peak in a frequency band in which the frequency of incident electromagnetic waves is 60 GHz or more and 90 GHz or less. A reflection attenuation amount at the maximum absorption peak is -15 dB or less, a reflection attenuation amount at the shoulder peak or the second peak is -10 dB or less, and a total film thickness of the electromagnetic wave absorption sheet is 500 μm or less.

Provided is an electromagnetic wave absorber capable of effectively absorbing an electromagnetic wave of a high frequency of a millimeter wave band or above, and capable of effectively absorbing an electromagnetic wave of a desired frequency even when a surrounding temperature change occurs. The electromagnetic wave absorber comprises, in a binder 1b, a magnetoplumbite-type hexagonal ferrite 1a that magnetically resonates in a frequency band of a millimeter wave band. In the magnetoplumbite-type hexagonal ferrite, some of metal sites are replaced with La. In a graph showing the relationship between the frequency of an incoming electromagnetic wave and the value of the imaginary part of the complex relative permeability of the electromagnetic wave absorber, when the temperature of the electromagnetic wave absorber changes from 25°C to 105° C, the value of the frequency at which a positive peak occurs shows a positive rate of change, and the ratio of the amount of change in the frequency at which a positive peak occurs when the temperature changes from 25°C to 105° C to the value of the frequency at which a positive peak occurs at 25°C is 1.5% or less.

The invention discloses a multiphase soft magnetic BaFe2O4 hexagonal ferrite material as well as a preparation method and application thereof, and belongs to the technical field of ferrite materials. The method comprises the following steps: (1) treating raw materials including Fe2O3, BaCO3, Bi2O3 and Co3O4 by adopting wet ball milling, and then drying and sieving to obtain raw material powder; (2) pre-sintering the raw material powder, grinding and sieving the obtained pre-sintered powder, then carrying out secondary wet ball milling, and then drying and sieving to obtain granulated powder; (3) adding a binder into the granulated powder, granulating, and then preparing into a green body; and (4) sintering the green body to obtain the multiphase soft magnetic BaFe2O4 hexagonal ferrite material. The method adopts a solid phase method for reaction, and has the advantages of simple process and convenience in large-scale production. The multiphase soft magnetic BaFe2O4 hexagonal ferrite material improves the upper limit of resonant frequency and low-loss application frequency, can meet the performance requirements of ultrahigh-frequency application, and has wide application prospects in the fields of wireless communication and the like.

The present invention provides hexagonal ferrite magnetic powder which is extremely useful in achieving both an increase in recording density and an increase in SNR of a magnetic recording medium, is crystalline and has a high saturation magnetization. The hexagonal ferrite magnetic powder contains Bi in a range of a Bi / Fe molar ratio of 0.035 or less, has a saturation magnetization σs of 42.0 Am 2 / kg or more, and a Dx volume of 1800 nm 3 or less, based on a microcrystal diameter. The magnetic powder can be produced by a method for producing hexagonal ferrite magnetic powder, comprising a process of immersing hexagonal ferrite magnetic powder containing Bi in a solution in which a compound X that forms a complex with Bi is dissolved, thereby performing a treatment of dissolving a part of the Bi present in the hexagonal ferrite magnetic powder into the solution.

The invention discloses a multi-doped Z-type hexagonal ferrite magnetoelectric coupling ceramic and a preparation method thereof, and belongs to the technical field of functional ceramics. The invention aims to solve the problems of low magnetoelectric coupling coefficient and low magnetoelectric coupling temperature of the existing Z-type hexagonal ferrite ceramic. The chemical formula of the magnetoelectric coupling ceramic disclosed by the invention is Ba < 1.5 > Sr < 1.5 > Co < 1.25 > Cu < 0.75 > Fe < 24-x > Al < x > O < 41 >. The method comprises the following steps: weighing raw materials SrCO3, BaCO3, Co3O4, CuO, Al2O3 and Fe2O3 according to the chemical formula, adding absolute ethyl alcohol and polyvinyl alcohol, carrying out wet ball milling, drying, uniformly grinding, and carrying out compression molding to obtain a green body; and discharging rubber, sintering in an oxygen atmosphere, cooling to 500 DEG C at a certain rate, and finally naturally cooling to room temperature. The maximum magnetoelectric coupling coefficient can reach 17.30 mV / (cm.Oe), the maximum magnetoelectric coupling temperature of the magnetoelectric coupling ceramic can reach 400 K or above, and compared with the prior art, the maximum magnetoelectric coupling temperature is greatly improved.

A low-loss hexagonal ferrite material in S and C bands and its preparation method, belonging to the technical field of ferrite material preparation. The hexagonal ferrite material includes a main phase and an additive. The main phase is Ba5Cu 2‑x Ni x Ti3Fe 12 O 31 , where x = 0.5 to 1, and the additive is SiO2; the additive accounts for 0.5 to 1.5 wt% of the mass of the main phase; by changing the ratios of Cu 2+ , Ni 2+ , the magnetocrystalline anisotropy, magnetic permeability and natural resonance frequency are regulated, and the real part of the magnetic permeability μ' ≥ 1.8, the magnetic loss tangent tanδ m ≤ 0.08, the real part of the dielectric constant ε' ≥ 10, and the dielectric loss tangent tanδ d ≤ 0.01 are achieved in the S and C bands. It can be used for the miniaturization of Sub-6GHz antennas, improving the antenna bandwidth and reducing the impedance mismatch.

The invention discloses a Z-type hexagonal ferrite magnetoelectric coupling ceramic material and a preparation method thereof. Belongs to the field of magnetoelectric coupling materials. The invention aims to solve the problems that the existing multiferroic material has ferroelectricity, has few ferromagnetism types, and is low in magnetoelectric coupling strength and low in magnetoelectric coupling tolerance temperature. The chemical formula of the material is Ba < x > Sr < 3-x > Co < 1.25 > Cu < 0.75 > Fe < 24 > O < 41 >, wherein x is equal to 0 to 3; the material is prepared by adopting a staged sintering method in an oxygen atmosphere. The product provided by the invention has both ferroelectricity and ferromagnetism and also has strong magnetoelectric coupling performance. The product can realize the performance of magnetoelectric coupling induced under the condition of externally applying a small magnetic field, the dynamic magnetoelectric coupling performance of the product can be regulated and controlled by the change of the directions of a pre-polarized electric field and an externally-applied sweep field, and the performance of the dynamic magnetoelectric coupling performance under the room temperature condition is broken through under the condition of a certain Ba doping ratio. The method can be applied to the field of magnetoelectric coupling. The application range of the magnetoelectric material is enriched and widened, and the material has potential application advantages.

The application discloses Y-type hexagonal ferrite material with dual magnetic heat effect and a preparation method and application thereof, belongs to the technical field of ferrite ceramic materials, and is denoted as Sr2Zn 2‑x Ni x Fe 12 O 22 (x=0.0, 0.8 or 2.0), and can be used as a heat sink composite material in the temperature range in which the inverse magnetic heat effect exists. For the Sr2Zn2Fe 12 O 22 material, a platform-shaped conventional magnetic heat effect exists near room temperature, is suitable for Ericsson magnetic refrigeration cycle, the magnetic entropy change and the relative refrigeration power gradually increase with the increase of the Ni ion doping amount, and reach the maximum when the doping amount is 0.8; under the condition that the magnetic field changes by 0-90kOe, the magnetic entropy change reaches 3.16J / kg K at 4K, -1.02J / kg K at 16K and 1.33J / kg K at 354K, and the corresponding relative refrigeration power is 358.68J / kg.

To provide a laminate having an epitaxial thin film of Y-type hexaferrite which can be formed without using a buffer layer, and to provide an element and a device.SOLUTION: The laminate includes a substrate and a film formed on the substrate. The film has an epitaxial layer comprising Y-type hexaferrite. The Y-type hexaferrite is represented by the general formula (Ba1 - xSrx) 2Co2Fe12 - y - δ AlyX δ O22. X is at least one element selected from the group consisting of Cr, Sb, In, and V. 0 ≤ x ≤ 1, 1 <y ≤ 6, and 0 ≤ δ ≤ 1.SELECTED DRAWING: Figure 1

A ferrite magnet includes: a hexagonal ferrite main phase; and a second phase. The second phase is an oxide phase containing: an element A which is at least one selected from the group consisting of Ca, Sr, Ba, Bi, and rare earth elements; a transition metal element T including at least Fe; and an element G which is at least one selected from the group consisting of Si, Al, B, F, K, Na, Li, P, and S. When the total number of atoms of the element A, the transition metal element T, and the element G in the second phase is set to 100 at %, the element A occupies 30 to 80 at %, the element G occupies 15 to 40 at %, and the transition metal element T occupies less than 4 at %.

The application relates to a preparation method of a high-coercivity high-remanence-ratio composite ferrite film material, which comprises the following steps: (1) preparing a BaFe9Al3O 19 ferrite target material;(2) depositing an amorphous BaFe9Al3O 19 ferrite film on an Al2O3 (000l) substrate by a pulse laser deposition method;(3) placing the grown amorphous BaFe9Al3O 19 ferrite film in a muffle furnace to perform annealing, so as to form BaFe2O4 and BaFe9Al3O 19 composite ferrite films.The application prepares a hexagonal ferrite target material with good compactness by solid-phase method and Al ion doping, and selects a pulse laser deposition technology to deposit a film; BaFe2O4 and BaFe9Al3O 19 composite films are formed by controlling the growth conditions of the film, the characteristics of soft and hard magnetic composite are fully exerted, the magnetic performance of the ferrite film is improved, and finally, the composite ferrite film material with the c-axis out-of-plane orientation and the high-coercivity characteristic is prepared.The application has the characteristics that the coercivity is greater than 1.83T, the remanence ratio reaches 93%, and the application has a good application prospect in the fields of self-biased microwave devices and magnetic recording.

Provided is a magnetic recording medium capable of suppressing recording speed dependency of electromagnetic conversion characteristics.　The magnetic recording medium is tape-shaped and includes a base body, a base layer, and a magnetic layer in this order. The average thickness of the magnetic recording medium is 4.40-5.40 μm, and the average thickness of the magnetic layer is 0.07 μm or less. The magnetic layer contains hexagonal ferrite particles containing barium (Ba) and strontium (Sr). The average particle volume of the hexagonal ferrite particles is 1.60 x 103 nm3 or less. The magnetic recording medium has an average value of a standardized SFD curve in the vertical direction thereof over a magnetic field range from 11,500-14,000 Oe of 0.013 or less, and demonstrates an average hardness H50, which is obtained by pushing a triangular pyramid diamond indenter having a ridge angle of 142.3° into the surface on the magnetic layer side at a right angle with a load of 50 μN, of 0.72 GPa or more.

The present application belongs to the field of ferrite thick film preparation, and particularly relates to a high orientation degree hexagonal ferrite thick film and a hot-pressing preparation method thereof. The present application aims at the problem that high orientation degree and high density of the hexagonal ferrite thick film are difficult to be realized simultaneously, and proposes a two-step hot-pressing sintering method to improve the orientation degree of the thick film. The low-temperature hot-pressing magnetic field orientation process and the high-temperature hot-pressing sintering process are organically combined to form a two-step hot-pressing sintering method for preparing the high-orientation and dense BaFe 12 O 19 thick film. The electromagnet and the heating plate in the low-temperature hot-pressing magnetic field orientation equipment are combined in a discrete manner, which effectively improves the stability of the magnetic field and is beneficial to the improvement of the orientation degree of the thick film.

There is provided a radio wave absorbing composition containing a magnetic powder and a binder. There is also provided a radio wave absorber containing a magnetic powder and a binder. The magnetic powder is a powder of a substitution-type hexagonal ferrite subjected to surface treatment with a surface treatment agent, and the binder is a polyamide.

Provided is a method for producing a magnetic powder, wherein degradation of magnetic characteristics can be suppressed.　This method for producing a magnetic powder includes: a step for cooling a melt of a granluar raw material to form amorphous bodies including crystal nuclei; a step for classifying the amorphous bodies; and a step for firing the classified amorphous bodies to precipitate hexagonal ferrite particles.

The application discloses a water-based tape casting slurry of a magnetoelectric composite ceramic sheet and a method for preparing the magnetoelectric composite ceramic sheet by water-based tape casting. 0.5 Na 0.4 K 0.1 TiO3, magnetic powder hexaferrite BaFe 12 O 19 , polyacrylic acid, polyurethane emulsion and polyacrylic acid emulsion mixture, polyethylene glycol and deionized water. The water-based tape casting process for preparing the magnetoelectric composite ceramic sheet comprises slurry preparation, tape casting, drying and sintering into a film, wherein a magnetic field is applied during the drying process of the wet film, and a composite structure of the magnetic powder oriented in the ferroelectric matrix is constructed. The magnetoelectric composite ceramic sheet prepared by the application has ferroelectricity and ferromagnetism, has a high magnetoelectric voltage coefficient and a magnetic dielectric response, and can be used in the fields of functional devices such as magnetoelectric sensors and energy converters; meanwhile, the ceramic sheet preparation process is simple, the conditions are easy to control, is environment-friendly and is suitable for batch production.

To provide a technique of producing magnetic powder of hexagonal ferrite, excellent in the effect of reducing the composition variation among production batches, relative to a conventional one.SOLUTION: A method of producing amorphous material for use in synthesizing hexagonal ferrite, comprises a mixing step of mixing raw material powder including a component for forming an amorphous body for use in synthesizing hexagonal ferrite and water, to obtain a mixture thereof, a granulation step of granulating the mixture to obtain a granular molding material, a heating / melting step of heating the granular molding material to obtain a molten body, and a rapid cooling step of rapidly cooling the molten body to obtain an amorphous body.SELECTED DRAWING: Figure 2

One embodiment of the present invention provides a method for manufacturing an electromagnetic wave absorbing material, the method comprising: a step of mixing a powder containing at least one selected from the group consisting of a Ca precursor, a Ba precursor, a Sr precursor, an Re precursor, an Me precursor, a Co precursor, and an Fe precursor; a step for performing a first heat treatment on the mixed powder; a step of ball-milling the powder after the heat treatment; and a step of performing a second heat treatment on the powder after the ball milling, thereby manufacturing an electromagnetic wave absorbing material including W-type hexagonal ferrite represented by the chemical formula 1. The present invention is a research result of a development subject of a microwave absorber for 5G communication (28GHz), which is supported by the Chang star (strain) and is executed by a first university production and study association group.

The magnetic powder for a radio wave absorber is a powder of a hexagonal ferrite having a composition represented by Formula 1, a region B is present on the particle surface of the powder, and Expression 2: 0.3≤content of A atom in region B / content of Al atom in region B≤23.0 and Expression 3: 1.2≤total of content of A atom and content of Al atom in region B / total of content of A atom and content of Al atom in entire powder≤2.5 are satisfied. The region B is a region that is observed as a bright region having a long side diameter of 0.1 μm to 0.6 μm in an image subjected to binarization processing. A represents one or more kinds of atoms (A atom) selected from the group consisting of Sr, Ba, Ca, and Pb, and x satisfies 0.10≤x≤5.00.AFe(12-x)AlxO19  (Formula 1)

The application discloses a preparation process of high-resistance M-type hexagonal ferrite and a prepared product, and belongs to the technical field of permanent magnet ferrite. The method comprises the following steps: step a, dosing: dosing pre-sintered materials and auxiliary materials according to a weight ratio, wherein the auxiliary materials include SiO2 0.05%-0.2%, CaCO3 0.5%, Al2O3 0.14% and HBO3 0.3% according to the mass percentage of the pre-sintered materials; step b, ball milling: putting the dosed materials and water in the step a into a ball mill and ball milling; and step c, sintering: sintering the mixture after the ball milling in the step b at 1175 DEG C.-1235 DEG C. The high-resistance M-type hexagonal ferrite prepared by the method has the following performances: Br 390-420 mT, Hcb 270-300 KA / m, Hcj 240-380 KA / m, (BH) max 31-33 kJ / m 3 , and the resistance is greater than 21 MΩ.

The ferrite magnet has a hexagonal ferrite main phase and a second phase. The second phase is an oxide phase containing: element A which is at least one selected from Ca, Sr, Ba, Bi, and a rare earth element; a transition metal element T which contains at least Fe; and element G which is at least one selected from Si, Al, B, F, K, Na, Li, P, and S. When the total atomic number of element A, the transition metal element T, and element G of the second phase is set to 100 at%, element A accounts for 30 to 80 at%, element G accounts for 15 to 40 at%, and the transition metal element T accounts for less than 4 at%.