26 results about "Hexagonal ferrite" patented technology

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.

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

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.

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.

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 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%.

To provide a magnetoplumbite-type hexagonal ferrite magnetic powder having electromagnetic wave absorbing capability in a 50 to 70 GHz band including a 60 GHz band, and having a small change in peak frequency of transmission attenuation over a wide temperature range, and a method for producing the same, and to provide an electromagnetic wave absorber using the magnetic powder and a method for producing the same.SOLUTION: This invention relates to a magnetoplumbite-type hexagonal ferrite magnetic powder, wherein a metallic element satisfies the general formula: A(1-x)RExFe(n-y-z)AlyCoz, indicating an atomic ratio (in the formula, A is one or more selected from the group consisting of Sr, Ba and Ca; RE is one or more of rare earth elements; 0.05≤x≤0.70; 0.01≤y<1.00; 0.00≤z≤1.00; 11.00≤n≤12.50).SELECTED DRAWING: Figure 1

Provided is an electromagnetic wave absorber which is capable of satisfactorily absorbing electromagnetic waves having a high frequency of at least a millimeter band, and which is also capable of satisfactorily absorbing electromagnetic waves having a desired frequency even when the ambient temperature changes. An electromagnetic wave absorber in which a magnetoplumbite-type hexagonal ferrite (1a) that performs magnetic resonance in a millimeter-band frequency band is contained in a binder (1b), said electromagnetic wave absorber being characterized in that: a part of metal sites of the magnetoplumbite-type hexagonal ferrite are substituted by La; in a graph representing the relationship between the frequency of the incident electromagnetic wave and the value of the imaginary part of the complex number relative permeability of the electromagnetic wave absorber, when the temperature of the electromagnetic wave absorber changes from 25 DEG C to 105 DEG C, the value of the frequency that becomes a positive peak shows a positive rate of change, and the value of the frequency that becomes a negative peak shows a positive rate of change. The ratio of the amount of change in the frequency of a positive peak when changed from 25 DEG C to 105 DEG C to the value of the frequency of a positive peak at 25 DEG C is 1.5% or less.

To provide a method for manufacturing a magnetoplumbite-type hexagonal ferrite magnetic powder capable of making a ferrite-based bond magnet exhibit excellent residual magnetization.SOLUTION: A first embodiment of the invention is a method of producing a magnetoplumbite-type hexagonal ferrite magnetic powder, including a firing step of firing a mixture containing a raw material powder and a metal chloride to obtain a fired product, and a pulverizing step of pulverizing the fired product to obtain a powder, in which a molar ratio of an amount of Cl contained in the metal chloride to an amount of Fe contained in the raw material powder is 0.002 or more and 0.020 or less.SELECTED DRAWING: None

The invention relates to a wide-frequency-band large-range adjustable equal-magnetic-dielectric hexagonal ferrite material and a preparation method thereof, and belongs to the technical field of advanced ferrite materials and preparation thereof. The chemical formula of the equimagnetic dielectric hexagonal ferrite material is Ba3xAxCo2 + xBxFe242xO41, A is one or more of Sr, Ca, Pb and other elements, B is one or more of Ti, Mo, Zr and other elements, and x is equal to 0.1-1. The magnetic conductivity and the dielectric constant of the material are cooperatively regulated and controlled through a multi-ion combined substitution technology, so that the material realizes large-range magnetic conductivity and dielectric constant matching in a wide frequency band, and the magnetic dielectric loss is relatively low. The method is based on a solid-phase reaction method, the process is mature and controllable, the production cost is low, and the method is suitable for large-scale industrial production.

To provide a hexagonal crystal ferrite magnetic powder for a bond magnet capable of obtaining a high residual magnetic flux density Br in the case of use for the bond magnet, a manufacturing method thereof, a bond magnet having a high residual magnetic flux density Br and a manufacturing method thereof.SOLUTION: The present invention relates to a manufacturing method of a hexagonal crystal ferrite magnetic powder for a bond magnet including the steps of: obtaining a mixed powder on which pulverization processing is performed by performing mixing pulverization of a coarse powder of hexagonal crystal ferrite and a fine powder of hexagonal crystal ferrite; and annealing the mixed powder on which the mixing pulverization processing is performed. Regarding the fine powder of hexagonal crystal ferrite, after a cylindrical die of which the inner diameter is 2.54 cmφ is filled with 10 g of the fine powder of hexagonal crystal ferrite, the relationship between a compression density X(g / cm3) of a mold compressed with a pressure of 1000 kg / cm2 and a specific surface area Y(m3 / g) of the fine powder of hexagonal crystal ferrite satisfies a relational expression of X>-0.03×Y+3.27.SELECTED DRAWING: Figure 1

The invention discloses an Mg-Zn < 18 > H hexagonal ferrite, the chemical formula of the Mg-Zn < 18 > H hexagonal ferrite is Ba < 5 > Mg < 2-x > Zn < x > Ti < 3 > Fe < 12 > O < 31 >, and x is more than 0 and less than 2. The invention also discloses a preparation method of the Mg-Zn 18H hexagonal ferrite, which comprises the following steps: S1, taking Fe2O3, MgO, ZnO, BaCO3 and TiO2 as raw materials, weighing the raw materials according to the atomic molar ratio in the chemical formula, putting the raw materials into a ball mill, carrying out wet ball milling, drying, and crushing to obtain a mixture; s2, the mixture is placed in a high-temperature furnace to be pre-sintered in a segmented mode; s3, taking out the mixture subjected to segmented pre-sintering, and cooling, grinding and screening the mixture to obtain precursor powder; and S4, putting the precursor powder into a discharge plasma sintering furnace, and sintering, so as to obtain the Mg-Zn 18H hexagonal ferrite. The Mg-Zn < 18 > H hexagonal ferrite disclosed by the invention has high density, fine and uniform grain structure and optimized magnetic performance.

This invention provides a praseodymium-dysprosium co-doped M-type hexagonal ferrite material, its preparation method, and its application. The chemical formula of the praseodymium-dysprosium co-doped M-type hexagonal ferrite material is A. y Fe 12‑2x Pr x Dy x O 19 Where A is strontium and / or barium, 0.05≤x≤1, 0.9≤y≤1.4. This invention incorporates praseodymium and dysprosium into M-type hexagonal ferrite, reducing grain size and forming polyhedral aggregates. Simultaneously, praseodymium-dysprosium co-doping can form various impurity phases, creating interfaces between the impurity phases and the main phase, effectively promoting interfacial polarization. Furthermore, Pr... 3+ To Pr 4+ The conversion favors oxygen vacancies and Fe 2+ The formation of praseodymium-dysprosium co-doped M-type hexagonal ferrite material improves the dielectric properties and microwave absorption properties of the material. Furthermore, the praseodymium-dysprosium co-doped M-type hexagonal ferrite material provided by this invention has advantages such as tunable absorption frequency band, high absorption intensity, and high operating temperature, exhibiting stable absorption performance and can be used as a base material for other composite materials.

The application provides a praseodymium-yttrium co-doped M-type hexagonal ferrite material and a preparation method and application thereof. z Fe 12‑x‑ y Pr x Y y O 19 , wherein 0.05<=x<=2.0, 0.05<=y<=1.5, 0.9<=z<=1.4, and x / y>1 / 7. The praseodymium and yttrium are doped into the M-type hexagonal ferrite, the characteristics of variable valence and large ion radius of praseodymium are utilized, and the Fe-deficient 3+ and Sr-rich 2+ environments are combined, so that Pr 4+ is formed, thereby reducing the grain size and forming a polyhedral aggregate, and meanwhile, the praseodymium-yttrium doping forms multiple impurities, interfaces are formed between the impurities and the main phase, and the interface polarization is promoted. The conversion of Pr 3+ to Pr 4+ is beneficial to the formation of oxygen vacancies and Fe 2+ , thereby significantly improving the dielectric properties of the material and enhancing the microwave absorption performance, and the material can be applied as a wave-absorbing material.

An effective and easily scaled-up chemical synthesis route to obtain L10 Iron-Nickel alloy from cyano / nitrosyl-metal complex precursor salts, for sustainable permanent magnets free of critical rare-earth elements, with a (BH)max ranging in between that 5 of hexaferrites (up tO~45 kJ / m3) and rare-earth-based permanent magnets (up to ~500 kJ / m3).

The application belongs to the technical field of ferrite material preparation, and specifically provides an X-band self-biased hexagonal gyromagnetic ferrite material based on Cr substitution and a preparation method thereof, so as to meet the engineering needs of X-band miniature integrated devices; the X-band self-biased hexagonal gyromagnetic ferrite material in the application comprises: a BaM hexagonal ferrite and an additive, wherein the chemical formula of the BaM hexagonal ferrite is BaCr x Fe 11.2‑x O 19‑δ , 0

The invention provides M-type hexagonal ferrite powder and a hydrothermal-precipitation preparation method thereof, and belongs to the technical field of magnetic ferrite preparation. The chemical composition of the M-type hexagonal ferrite powder is (BaxSryCaz) (Fe12-a-bCoaZnb) O19, x + y + z = 1, x, y and z are all larger than or equal to 0 and are not 0 at the same time, a + b is smaller than or equal to 12, a and b are both larger than or equal to 0, a hydrothermal-precipitation method is adopted for preparation, and precipitation liquid in the precipitation method is NaOH solution. The hydrothermal-precipitation preparation method developed by the invention is simple and convenient to operate, simple in process flow and high in adaptability, and the obtained M-type ferrite is stable in structure and good in performance.

This invention discloses a Z-type hexagonal ferrite magnetoelectric coupling ceramic material and its preparation method; belonging to the field of magnetoelectric coupling materials. This invention aims to solve the problems of existing multiferroic materials having limited ferroelectric and ferromagnetic properties, low magnetoelectric coupling strength, and low magnetoelectric coupling tolerance temperature. The chemical formula of the material of this invention is: Ba. x Sr 3‑x Co 1.25 Cu 0.75 Fe 24 O 41 Where x = 0 to 3; prepared by a staged sintering method under an oxygen atmosphere. The product of this invention possesses both ferroelectric and ferromagnetic properties, along with strong magnetoelectric coupling performance. This product can achieve magnetoelectric coupling performance induced under a small external magnetic field, and its dynamic magnetoelectric coupling performance can be controlled by changing the direction of the pre-polarized electric field and the applied sweep field. Furthermore, under a certain Ba doping ratio, it surpasses the dynamic magnetoelectric coupling performance at room temperature, and can be applied in the field of magnetoelectric coupling. This enriches and broadens the application range of magnetoelectric materials, possessing potential application advantages.

[Problem] A hexagonal barium ferrite magnetic powder formed of fine particles, wherein the anisotropic magnetic field distribution of a magnetic recording medium can be made to fall within a range effective in both improving the recording density and improving the SNR is provided.[Solution] A magnetic powder for a magnetic recording medium including magnetic particles in which Ba in hexagonal barium ferrite is partially substituted with Sr, wherein a Dx volume represented by the following formula (1) is 2,200 nm3 or less, an Sr / (Ba+Sr) molar ratio is 0.01 to 0.30, and an anisotropic magnetic field distribution is 1.00 or less.Dx volume (nm3)=Dxc×π×(Dxa / 2)2  (1)Here, Dxc is a crystallite diameter (nm) in a c-axis direction of a hexagonal ferrite crystal lattice, Dxa is a crystallite diameter (nm) in an a-axis direction of the same crystal lattice, and π is a circular constant.