Sheet branch type magnetic nano material as well as preparation and application thereof

Abstract

The invention relates to a sheet-branch type magnetic nano material and preparation and application thereof, the nano material is a CoNi alloy material, and the shape of the nano material is a sheet-branch type formed by combining a one-dimensional chain shape and a two-dimensional sheet shape. Compared with the prior art, the nano material has excellent saturation magnetization and electromagnetic wave absorption performance, the process is simple, the structure is controllable, and a new solution is provided for development of high-performance electromagnetic wave absorption materials.

Description

Technical Field

[0001] The present invention belongs to the technical field of magnetic nanomaterial preparation, and relates to a sheet-branch type magnetic nanomaterial and its preparation and application. Background Art

[0002] With the rapid development of electronic components and communication technologies, the operating frequency of devices continues to extend to the GHz range and even higher. In a high-frequency environment, the electromagnetic interference problem becomes increasingly serious, posing higher requirements for the performance stability and electromagnetic compatibility of electronic devices. To solve this problem, electromagnetic wave absorbing materials have gradually become a research hotspot, and among them, magnetic materials have attracted much attention due to their excellent magnetic loss ability and electromagnetic wave absorption performance.

[0003] Traditional magnetic materials (such as spherical, sheet-like, or simple chain-like structures) usually exhibit high magnetic permeability and saturation magnetization in the MHz frequency band, and can effectively shield and absorb electromagnetic waves. However, when the frequency rises to the GHz range, the performance of these materials is restricted by the Snoek limit, resulting in a sharp decline in magnetic permeability and wave absorption ability. The Snoek limit indicates that the magnetic permeability is proportional to the saturation magnetization and inversely proportional to the resonance frequency, and this inherent contradiction limits the comprehensive performance of traditional magnetic materials in the high-frequency band. In recent years, through the optimized design of the morphology of magnetic materials, researchers have tried to break through the Snoek limit to improve their high-frequency performance. For example, simple sheet-like materials and chain-like materials rely on their high specific surface area and one-dimensional continuity respectively, and can partially improve the magnetic loss ability, but the optimization of a single dimension is difficult to take into account both broadband wave absorption performance and magnetic stability.

[0004] For example, Chinese Patent CN202411595571.4 discloses a dielectric and magnetic loss coupling type multi-frequency high-absorption composite wave-absorbing material. This solution adopts a process path of vacuum atomization combined with repeated ball milling doping, and realizes the sheet-like formation of high-entropy alloys through multiple mechanical treatments (atomization → ball milling → doping → secondary ball milling). This multi-step process not only leads to an extended preparation cycle and increased energy consumption, but also the final obtained sheet-like morphology is single, and it is unable to effectively improve the high-frequency performance. Summary of the Invention

[0005] The purpose of the present invention is to provide a sheet-branch type magnetic nanomaterial and its preparation and application, by constructing a multi-dimensional composite structure combining the characteristics of one-dimensional chain-like and two-dimensional sheet-like, overcoming the limitations of traditional magnetic materials in high-frequency electromagnetic wave absorption performance, etc.

[0006] The purpose of the present invention can be achieved by the following technical solutions:

[0007] In the first aspect, the present invention provides a sheet-branch type magnetic nanomaterial, which is a CoNi alloy material, and its shape is a sheet-branch type formed by the combination of one-dimensional chain-like and two-dimensional sheet-like.

[0008] In a second aspect, the present invention provides a method for preparing a flake-branch type magnetic nanomaterial, comprising the following steps:

[0009] S1. Take cobalt acetate and nickel acetate and mix them, add a surfactant, dissolve them in an organic solvent, and stir evenly;

[0010] S2. Transfer the homogeneous solution obtained in S1 to a hydrothermal reaction kettle, carry out a solvothermal reaction to obtain a flake-branch type magnetic nanomaterial.

[0011] Further, in S1, the ratio of cobalt acetate to nickel acetate is 1:4 to 4:1.

[0012] Further, in S1, the organic solvent is ethylene glycol.

[0013] Further, in S1, the ratio of the total molar amount of cobalt acetate and nickel acetate to the addition amount of the organic solvent is (0.05 - 0.25) mol: 25 mL. Preferably, it is 0.1 - 0.2 mol: 25 mL.

[0014] Further, in S1, the surfactant is polyethylene glycol. Even further, in S1, the addition amount of the surfactant is 0.5 - 2% of the total mass of the reaction system including the solvent.

[0015] Further, in S2, the temperature of the solvothermal reaction is 150 - 250 °C.

[0016] Further, in S2, the time of the solvothermal reaction is 12 - 20 h.

[0017] In a third aspect, the present invention provides an application of the flake-branch type magnetic nanomaterial in radar stealth, electromagnetic wave absorption, and electromagnetic interference protection of electronic devices. During specific application, the minimum value of the reflection loss of the flake-branch type magnetic nanomaterial in the 8.4 GHz frequency band is -58.18 dB, and the effective absorption bandwidth (EAB) is 2.8 GHz (11.7 - 14.5 GHz).

[0018] Compared with the prior art, the present invention has the following advantages:

[0019] (1) The obtained flake-branch type magnetic nanomaterial has a multi-dimensional composite structure combining one-dimensional chain-like and two-dimensional flake-like characteristics, significantly improving the magnetic properties;

[0020] (2) The material exhibits high reflection loss and broadband wave absorption performance, and can be widely applied to radar stealth technology;

[0021] (3) The preparation method of the present invention has a simple process, strong controllability, and is suitable for large-scale industrial production;

[0022] (4) The materials of the present invention exhibit excellent performance in the field of high-frequency electromagnetic wave absorption, providing important technical support for the development of wave-absorbing materials. Description of the Drawings

[0023] Figure 1 SEM image of the prepared sheet-branched magnetic nanomaterials in Example 1;

[0024] Figure 2 X-ray diffraction spectrum of the prepared sheet-branched magnetic nanomaterials in Example 1;

[0025] Figure 3 Electrical parameters of the prepared sheet-branched magnetic nanomaterials in Example 1 in the 2-18 GHz band;

[0026] Figure 4 Magnetic parameters of the prepared sheet-branched magnetic nanomaterials in Example 1 in the 2-18 GHz band;

[0027] Figure 5 Reflection rate test chart of the prepared sheet-branched magnetic nanomaterials in Example 1 in the 2-18 GHz band;

[0028] Figure 6 SEM image of the prepared sheet-branched magnetic nanomaterials in Example 2;

[0029] Figure 7 SEM image of the product synthesized in Comparative Example 1;

[0030] Figure 8 SEM image of the product synthesized in Comparative Example 2;

[0031] Figure 9 SEM image of the product synthesized in Comparative Example 3. Detailed Description of the Invention

[0032] The present invention will be described in detail below with reference to the drawings and specific examples. This example is implemented on the premise of the technical solution of the present invention, and the detailed implementation manners and specific operation processes are given, but the protection scope of the present invention is not limited to the following examples.

[0033] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the technical field to which this application belongs. The terms used in the specification of this application herein are only for the purpose of describing specific embodiments and are not intended to limit this application.

[0034] As used herein, the selection scope of the terms "and / or", "or / and", "and / or" includes any one of two or more related listed items, and also includes any and all combinations of the related listed items. The any and all combinations include combinations of any two related listed items, any more related listed items, or all related listed items. It should be noted that when at least three items are connected by at least two conjunctions selected from "and / or", "or / and", "and / or", it should be understood that in this application, this technical solution undoubtedly includes the technical solution connected by "logical AND", and also undoubtedly includes the technical solution connected by "logical OR".

[0035] In this application, among the technical features described in an open-ended manner, it includes a closed technical solution composed of the listed features, and also includes an open technical solution containing the listed features.

[0036] In this application, regarding the numerical range, unless otherwise specified, the above numerical range is considered continuous, and includes the minimum value and the maximum value of this range, as well as each value between this minimum value and the maximum value. Further, when the range refers to an integer, it includes each integer between the minimum value and the maximum value of this range. In addition, when multiple ranges are provided to describe features or characteristics, these ranges can be combined. In other words, unless otherwise specified, all ranges disclosed herein should be understood to include any and all sub-ranges subsumed therein.

[0037] In this article, only some numerical ranges are specifically disclosed. However, any lower limit can be combined with any upper limit to form a range not explicitly recorded; and any lower limit can be combined with other lower limits to form a range not explicitly recorded. Similarly, any upper limit can be combined with any other upper limit to form a range not explicitly recorded. In addition, each separately disclosed point or single numerical value itself can be used as a lower limit or an upper limit and combined with any other point or single numerical value or combined with other lower limits or upper limits to form a range not explicitly recorded.

[0038] For the temperature parameter in this application, unless otherwise specifically limited, it allows both constant temperature treatment and treatment within a certain temperature range. The constant temperature treatment allows the temperature to fluctuate within the accuracy range controlled by the instrument. It is allowed to fluctuate within a range such as ±5°C, ±4°C, ±3°C, ±2°C, ±1°C.

[0039] In this article, the "suitable" in "suitable combination method", "suitable method", "any suitable method", etc. is subject to being able to implement the technical solution of this application, solve the technical problems of this application, and achieve the expected technical effects of this application.

[0040] In this application, words such as "further", "even further", and "especially" are used for descriptive purposes to indicate differences in content, but should not be construed as limiting the scope of protection of this application.

[0041] In this application, "optionally", "optional", and "option" mean that something is either present or absent, that is, it refers to either one of two alternative scenarios: "present" or "absent". If the term "optional" appears multiple times in a technical solution, and there is no special instruction, no contradiction, or no mutual restriction relationship, then each "optional" is independent of the others.

[0042] In the description of the application, the meaning of "a plurality of" is at least two, such as two, three, etc., unless otherwise specifically defined.

[0043] Unless otherwise specified, all formulations and tests in this article are carried out in an environment of 25°C.

[0044] In this article, "comprising", "including", "containing", "having", or other variants are intended to cover non-exclusive inclusion, and no distinction is made between these terms. The term "including" means that other steps and components can be added without affecting the final result. The compositions and methods / processes of the present invention comprise, consist of, and consist essentially of the essential elements and limitations described herein, as well as any additional or optional components, ingredients, steps, or limitations described herein. In this article, no distinction is made between the terms "efficacy", "performance", "effect", and "function".

[0045] If there is no special instruction, all embodiments and optional embodiments of this application can be combined with each other to form a new technical solution. If there is no special instruction, all technical features and optional technical features of this application can be combined with each other to form a new technical solution.

[0046] If there is no special instruction, all steps of this application can be carried out sequentially or randomly, preferably sequentially.

[0047] Example 1

[0048] Preparation of sheet-branch type magnetic nanomaterials:

[0049] First, cobalt acetate and nickel acetate are weighed in a molar ratio of 4:1, with a total addition amount of 0.1 mol, and dissolved in 25 mL of ethylene glycol, and stirred for 15 minutes to form a homogeneous solution; then, polyethylene glycol (PEG2000) is added to the solution, with an addition amount of 1% of the total mass of the reaction system, and stirring is continued until completely mixed; then, the obtained solution is transferred to a hydrothermal reaction kettle and reacted at 180°C for 12 hours; finally, the reaction product is cooled to room temperature, and the sheet-branch type magnetic nanomaterials are collected.

[0050] Example 2

[0051] Compared with Example 1, most of them are the same, except that the molar ratio of cobalt acetate and nickel acetate is changed to 1:4, the total addition amount is changed to 0.2 mol, the hydrothermal reaction temperature is 220 °C, and the reaction time is 24 hours.

[0052] The microstructure of the sheet-branch type magnetic nanomaterials obtained in the above examples was characterized by scanning tunneling microscopy (SEM, Hitachi S-4800); the X-ray diffraction spectrum was measured using a Bruker D8 Advance instrument; the complex relative permittivity and permeability were tested in the frequency range of 2.0–18.0 GHz using a vector network analyzer of model N5230C.

[0053] Figure 1 Figure 9 is a scanning electron microscope image of the sheet-branch type magnetic nanomaterials prepared in Example 1. It can be seen from the microscopic morphology that the whole is randomly covered with sheet structures on the magnetic chains, and the chain diameter is 3 microns.

[0054] Figure 2 Figure 13 is the X-ray diffraction (XRD) analysis of the sheet-branch type magnetic nanomaterials prepared in Example 1 above. In the figure, the material of Example 1 shows a face-centered cubic alloy peak type.

[0055] Figure 3 Figure 17 is the complex dielectric parameter of the sheet-branch type magnetic nanomaterials prepared in Example 1. At 2 GHz, the real part is 32.4 and the imaginary part is 0.38.

[0056] Figure 4 Figure 21 is the complex permeability of the sheet-branch type magnetic nanomaterials prepared in Example 1. At 2 GHz, the real part is 1.42 and the imaginary part is 0.42.

[0057] Figure 5 Figure 25 is the reflection loss value of the sample pressed from the sheet-branch type magnetic nanomaterials prepared in Example 1 at a thickness of 1.0–5.0 mm in the frequency range of 2.0–18.0 GHz. It can be seen from the figure that the material has the significant advantage of high reflection loss: it shows excellent electromagnetic wave loss ability in the frequency range of 2.0–18.0 GHz. Among them, at a frequency of 8.4 GHz, the maximum reflection loss reaches -58.2 dB, achieving an effective absorption level of 99.9999%, showing the potential application value as a high-performance microwave absorbing material.

[0058] Figure 6 Figure 29 is a scanning electron microscope image of the sheet-branch type magnetic nanomaterials prepared in Example 2. It can be seen from the microscopic morphology that the whole is randomly covered with sheet structures on the magnetic chains, and the chain diameter is 5 microns.

[0059] Comparative Example 1:

[0060] Compared with Example 1, most of them are the same, except that the addition of the surfactant is omitted.

[0061] Comparative Example 2:

[0062] Compared with Example 1, most of them are the same, except that the addition of cobalt element is omitted.

[0063] Comparative Example 3:

[0064] Compared with Example 1, most of them are the same, except that the surfactant is changed to an equal mass of PVP (K30).

[0065] Figure 7 The SEM image of the product synthesized in Comparative Example 1. Compared with Example 1, the flaky structure cannot grow, resulting in a decrease in the surface area of the sample and a single magnetic structure.

[0066] Figure 8 The SEM image of the product synthesized in Comparative Example 2. Compared with Example 1, the chain-like structure cannot grow, lacking magnetic anisotropy.

[0067] Figure 9 The SEM image of the product synthesized in Comparative Example 3. Compared with Example 1, the flaky structure cannot grow, showing a wrinkled surface and a single magnetic structure.

[0068] The above description of the embodiments is for those of ordinary skill in the art to understand and use the invention. It is obvious that those skilled in the art can easily make various modifications to these embodiments and apply the general principles described herein to other embodiments without creative labor. Therefore, the present invention is not limited to the above embodiments, and the improvements and modifications made by those skilled in the art without departing from the scope of the present invention should be within the protection scope of the present invention.

Claims

1. A dendrite-type magnetic nanomaterial, characterized in that: It is a CoNi alloy material, and its shape is a branch-shaped structure formed by the combination of one-dimensional chain and two-dimensional sheet.

2. The method for preparing a dendrite-type magnetic nanomaterial according to claim 1, characterized in that: The following steps are involved: S1, mix cobalt acetate and nickel acetate, add surfactant, dissolve in organic solvent, and stir evenly; S2. The uniform solution obtained in S1 is transferred to a hydrothermal reactor to carry out a solvothermal reaction to obtain a dendritic magnetic nanomaterial.

3. The method for preparing a dendrite-type magnetic nanomaterial according to claim 2, characterized in that: In S1, the ratio of cobalt acetate to nickel acetate is 1:4 to 4:

1.

4. The method for preparing a dendrite-type magnetic nanomaterial according to claim 2, characterized in that: In S1, the organic solvent is ethylene glycol.

5. The method for preparing a dendrite-type magnetic nanomaterial according to claim 2, characterized in that: In S1, the ratio of the total molar amount of cobalt acetate and nickel acetate to the added amount of the organic solvent is (0.05-0.25) mol:25 mL.

6. The method for preparing a dendrite-type magnetic nanomaterial according to claim 2, characterized in that: In S1, the surfactant is polyethylene glycol.

7. The method for preparing a dendrite-type magnetic nanomaterial according to claim 6, characterized in that: In S1, the added amount of the surfactant is 0.5-2% of the total mass of the reaction system including the solvent.

8. The method for preparing a dendrite-type magnetic nanomaterial according to claim 2, characterized in that: In S2, the temperature of the solvothermal reaction is 150-250°C.

9. The method for preparing a dendrite-type magnetic nanomaterial according to claim 2, characterized in that: In S2, the solvent thermal reaction time is 12 to 20 hours.

10. Application of the dendritic magnetic nanomaterial as claimed in claim 1 in radar stealth, electromagnetic wave absorption, and electromagnetic interference protection of electronic devices.

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