12 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 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.

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.

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

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