MnCo-based metal oxide electromagnetic wave absorbing material and preparation method and application thereof

Abstract

The invention relates to a MnCo-based metal oxide electromagnetic wave absorbing material as well as a preparation method and application thereof. The composition of the MnCo-based metal oxide electromagnetic wave absorbing material is Mn2. 05Co0. 91 O4, the preparation method comprises the following steps: preparing raw materials from a cobalt source, a manganese source, urea and ammonium persulfate according to a molar ratio, and dissolving the raw materials in deionized water to obtain a metal salt solution; carrying out hydrothermal reaction; centrifugally washing, drying and grinding; and calcining, and directly quenching after calcining to finally obtain the MnCo-based metal oxide electromagnetic wave absorbing material. The MnCo-based metal oxide electromagnetic wave absorbing material disclosed by the invention has excellent wave absorbing performance: by changing a quenching medium, customizing the lattice strain of the MnCo-based metal oxide, inducing the generation of unpaired electrons and optimizing the dielectric property of the MnCo-based metal oxide electromagnetic wave absorbing material, the wave absorbing performance of the MnCo-based metal oxide electromagnetic wave absorbing material is finally improved; the preparation process is simple and easy to implement, the metal oxide material with excellent and stable wave-absorbing performance is prepared through simple hydrothermal reaction, calcination and quenching processes, and the metal oxide material has great application prospects.

Description

Technical Field

[0001] The invention relates to the technical field of electromagnetic wave absorbing materials, and in particular to a MnCo-based metal oxide electromagnetic wave absorbing material and a preparation method and application thereof. Background Art

[0002] The increasing popularity of artificial intelligence (AI) technology and 5G / 6G devices has made electromagnetic compatibility issues more prominent, emphasizing the importance of studying and applying electromagnetic wave absorbing materials. In addition, the practical application of smart devices in multifunctional and wide-spectrum working environments has also posed new challenges to the absorption bandwidth of electromagnetic wave absorbing materials. In the past two decades, metal oxides have been a hot research topic in electromagnetic wave absorbing materials due to their abundant resources, long-term chemical stability, easy synthesis, large-scale production and low price. The key to achieving wide bandwidth lies in tailoring electromagnetic parameters and frequency stability, electronic band structure and charge behavior to adjust dielectric properties. However, existing methods rely on trial and error to generate complex dielectric loss sources and lack a direct connection between dielectric loss factors and effective absorption bandwidth (EAB). Therefore, researchers need to develop new methods to overcome these complex dielectric loss mechanisms to achieve electromagnetic wave absorbing materials with wide EAB.

[0003] Compared with traditional chemical doping or material interface engineering, strain engineering is considered to be a more stable and controllable method to adjust the electronic band structure of materials. However, the current methods for synthesizing strain-effect structures are complex and time-consuming, which complicates the understanding of how lattice strain affects electromagnetic properties and its corresponding intrinsic mechanisms, and limits the widespread application of strain engineering in broadening EABs. Therefore, exploring more effective synthesis methods is crucial to better understand the role of strain engineering in electromagnetic wave absorbing materials. Recently, quenching technology has shown great potential in ultrafast manufacturing of metal alloys, metallic glasses and metal oxides, and has made significant progress.

[0004] However, there has been no systematic study on the enhancement of EAB performance by quenching, and the mechanism by which the corresponding strain engineering broadens oxide EAB is not fully understood. Summary of the invention

[0005] The purpose of the present invention is to provide a MnCo-based metal oxide electromagnetic wave absorbing material and its preparation method and application in order to solve the above problems. Through simple hydrothermal reaction, annealing and quenching treatment process and grinding, an excellent and stable electromagnetic wave absorbing material is prepared to solve the problem of narrow EAB and low electromagnetic wave absorption performance of metal oxides.

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

[0007] The first object of the present invention is to provide a MnCo-based metal oxide electromagnetic wave absorbing material, wherein the composition of the MnCo-based metal oxide is Mn 2.05 Co 0.91 O4; This material has excellent electromagnetic wave absorption performance.

[0008] The second object of the present invention is to provide a method for preparing the above-mentioned MnCo-based metal oxide electromagnetic wave absorbing material, the preparation method comprising the following steps:

[0009] S1: Cobalt source, manganese source, urea and ammonium persulfate are mixed according to the chemical formula Mn 2.05 Co 0.91 The raw materials are prepared in a molar ratio of 0.04; the raw materials are fully stirred in deionized water to obtain a metal salt solution;

[0010] S2: subjecting the prepared metal salt solution to a hydrothermal reaction to obtain a precursor solution;

[0011] S3: washing the prepared precursor solution by centrifugation, drying the obtained precipitate and grinding it to obtain a precursor metal oxide powder;

[0012] S4: The obtained precursor metal oxide powder is calcined and quenched to obtain a metal oxide powder, namely, a MnCo-based metal oxide electromagnetic wave absorbing material.

[0013] Preferably, in step S1, the cobalt source is cobalt nitrate hexahydrate with a purity of not less than 99.9%, the manganese source is manganese sulfate monohydrate with a purity of not less than 99.9%, and the purity of urea and ammonium persulfate are both not less than 99.9%. The higher purity of the raw materials can ensure that the performance of the final product is better.

[0014] Preferably, in step S1, the metal ions in the metal salt solution include cobalt in the cobalt source and manganese in the manganese source; the molar ratio of the total amount of metal ions (the total amount of cobalt in the cobalt source and the total amount of manganese in the manganese source): urea: ammonium persulfate is 5:3:1; the amount of deionized water is not limited, generally speaking, it is sufficient to ensure that the above-mentioned raw materials can be completely dissolved. In some specific embodiments, when the total amount of metal ions is 5 mmol, the amount of deionized water is 40 mL, and in other embodiments, it can be appropriately adjusted according to this ratio.

[0015] Preferably, in step S1, the metal salt solution is fully stirred for 20 to 40 minutes.

[0016] As a further preferred embodiment of the preparation method of the present invention, wherein: in step S1, the metal salt solution is obtained by magnetic stirring, and the stirring time is 30 minutes.

[0017] Preferably, in step S2, the hydrothermal reaction temperature is 160-180° C., and the reaction time is 180-240 min.

[0018] In some specific embodiments of the present application, in step S2, the hydrothermal reaction is carried out in a hydrothermal reactor with a capacity of 100 mL. In some embodiments not shown, the volume of the reactor can be selected according to the actual amount of raw materials, and the 100 mL mentioned here is not a limitation of the present application.

[0019] Preferably, in step S3, the centrifugal washing is washing three times with deionized water and ethanol solution respectively, the centrifugal speed is 4000 rpm, and the centrifugal time is 2 to 4 minutes.

[0020] Preferably, in step S3, the drying is preferably carried out in a vacuum drying oven for 12 to 14 hours at a temperature of 58 to 62°C.

[0021] Preferably, in step S4, the calcination temperature is 250-400° C., and the calcination time is 2-4 hours;

[0022] Preferably, in step S4, the quenching medium is any one of air, room temperature deionized water, and frozen deionized water. The quenching is: taking the calcined sample directly out of the highest temperature state and immersing it in a cooling medium.

[0023] The third object of the present invention is to provide an application of the above-mentioned MnCo-based metal oxide electromagnetic wave absorption material, and to use the MnCo-based metal oxide electromagnetic wave absorption material for electromagnetic wave absorption in the field of artificial intelligence and 5G / 6G equipment.

[0024] Compared with the prior art, the present invention has the following beneficial effects:

[0025] (1) The MnCo-based metal oxide prepared by the present invention has excellent electromagnetic wave absorption performance, and can be prepared by simple hydrothermal reaction, annealing and quenching process and grinding to obtain an excellent and stable electromagnetic wave absorption material. The preparation process is simple and easy, and a MnCo-based metal oxide electromagnetic wave absorption material with excellent and stable electromagnetic wave absorption performance can be prepared by simple hydrothermal reaction, annealing and quenching process and grinding technology, which has great application prospects.

[0026] (2) The present invention customizes the lattice strain of the MnCo-based metal oxide by changing the quenching medium, induces the generation of unpaired electrons, optimizes its dielectric properties, and ultimately adjusts its electromagnetic wave absorption performance.

[0027] (3) The absorber comprising the MnCo-based metal oxide electromagnetic wave absorbing material of the present invention has a wide EAB of 7.52 GHz when the thickness is only 2.47 mm, and the minimum reflection loss reaches -67.41 dB when the thickness is 3.14 mm, showing an extraordinary electromagnetic wave absorption ability.

[0028] (4) The MnCo-based metal oxide electromagnetic wave absorbing material provided by the present invention is low-cost, eco-friendly, and can effectively reduce electromagnetic radiation interference / pollution. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for describing the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative labor. Among them:

[0030] Figure 1 It is the XRD spectrum of the MnCo-based metal oxide electromagnetic wave absorbing material prepared in Examples 1 to 3 and Comparative Example 1;

[0031] Figure 2 TEM images of the MnCo-based metal oxide electromagnetic wave absorbing materials prepared in Examples 1 to 3 and Comparative Example 1, wherein a, Comparative Example 1, b, Example 1, c, Example 2, d, Example 3;

[0032] Figure 3 It is a graph of the electromagnetic wave absorption performance of the MnCo-based metal oxide electromagnetic wave absorption material prepared in Examples 1 to 3 and Comparative Example 1, wherein a, Comparative Example 1, b, Example 1, c, Example 2, d, Example 3. DETAILED DESCRIPTION

[0033] In order to enable those skilled in the art to better understand the technical solution of the present invention, the present invention is described in detail below in conjunction with specific embodiments. It should be pointed out that the following embodiments will help those skilled in the art to further understand the present invention, but do not limit the present invention in any form. It should be pointed out that for those of ordinary skill in the art, several variations and improvements can also be made without departing from the concept of the present invention. These all belong to the protection scope of the present invention. In the following description, many specific details are set forth in order to fully understand the present invention, but the present invention can also be implemented in other ways different from those described herein, and those skilled in the art can make similar promotions without violating the connotation of the present invention, so the present invention is not limited by the specific embodiments disclosed below.

[0034] Secondly, the term "one embodiment" or "embodiment" as used herein refers to a specific feature, structure, or characteristic that may be included in at least one implementation of the present invention. The term "in one embodiment" that appears in different places in this specification does not necessarily refer to the same embodiment, nor does it refer to a separate or selective embodiment that is mutually exclusive with other embodiments.

[0035] All raw materials of the present invention have no particular limitation on their sources, and can be purchased from the market or prepared according to conventional methods known to those skilled in the art.

[0036] Example 1 A Mn 2.05 Co 0.91 O4 Metal Oxide Electromagnetic Wave Absorption Material

[0037] This embodiment provides a Mn 2.05 Co 0.91 The preparation method of O4 metal oxide electromagnetic wave absorbing material comprises the following steps:

[0038] (1) Cobalt nitrate hexahydrate, manganese sulfate monohydrate, urea and ammonium persulfate with a purity of not less than 99.9% are mixed with a nominal composition of Mn 2.05 Co 0.91 O4, a metal salt solution was prepared by fully magnetic stirring in deionized water for 30 min, wherein the molar ratio of the total amount of metal ions: urea: ammonium persulfate was 5:3:1, the total amount of metal ions was fixed at 5 mmol, and the amount of deionized water was 40 mL;

[0039] (2) placing the metal salt solution prepared in step (1) into the inner lining of a hydrothermal reactor, placing the high-pressure reactor in the center of a muffle furnace, heating the muffle furnace to 180° C. at a heating rate of 2.0° C. / min, and keeping the temperature for 240 min. After being fully cooled, taking out the metal salt solution, which is a precursor solution;

[0040] (3) washing the metal salt solution obtained in step (2) with deionized water and ethanol solution three times alternately to obtain a precipitated sample, and drying the precipitated sample in a vacuum drying oven at 60° C. for 12 h to obtain a metal oxide precursor powder;

[0041] (4) After the metal oxide precursor powder sample obtained in step (3) is fully ground, it is placed in a muffle furnace for calcination, and the temperature is increased from room temperature to 350°C at a heating rate of 5.0°C / min, and the temperature is kept for 3 hours. After the insulation is completed, it is directly taken out from the furnace and cooled in air to obtain a metal oxide powder sample after air quenching, i.e., a MnCo-based metal oxide electromagnetic wave absorbing material.

[0042] Example 2 A Mn 2.05 Co 0.91 O4 Metal Oxide Electromagnetic Wave Absorption Material

[0043] This embodiment provides a Mn 2.05 Co 0.91 Preparation method of O4 metal oxide electromagnetic wave absorbing material. The difference between Example 2 and Example 1 is that the quenching medium is different. The quenching medium of this example is deionized water at room temperature, and the other steps are the same as Example 1.

[0044] Example 3 A Mn 2.05 Co 0.91 O4 Metal Oxide Electromagnetic Wave Absorption Material

[0045] This embodiment provides a Mn 2.05 Co 0.91 Preparation method of O4 metal oxide electromagnetic wave absorbing material. The difference between Example 3 and Example 1 is that the quenching medium is different. The quenching medium of this example is frozen deionized water, and the other steps are the same as Example 1.

[0046] Comparative Example 1 A Mn 2.05 Co 0.91 O4 Metal Oxide Electromagnetic Wave Absorption Material

[0047] This comparative example provides a Mn 2.05 Co 0.91 Preparation method of O4 metal oxide electromagnetic wave absorbing material. The difference between this comparative example and Example 1 is that no quenching is performed. After the furnace reaches the highest temperature, this comparative example slowly cools to room temperature in the furnace. The other steps are the same as Example 1.

[0048] For the above Mn 2.05 Co 0.91 Performance testing of O4 metal oxide electromagnetic wave absorbing materials:

[0049] (I) Phase Analysis: In order to illustrate the effect of changing the quenching medium on the phase content of the MnCo-based metal oxide and observe the change in the phase content of the MnCo-based metal oxide, the electromagnetic wave absorbing materials prepared in Examples 1 to 3 and Comparative Example 1 were subjected to XRD tests. The results are as follows: Figure 1 As shown in the figure, it can be seen that the electromagnetic wave absorbing materials prepared in Comparative Example 1 and Examples 1 to 3 are all [I 41 / amd:1] type intermetallic phase (Co,Mn)(Co,Mn)2O4 and [I 41 / amd:1] type intermetallic phase (Co,Mn)2O4.

[0050] Table 1 is based on Figure 1 The results show the phase content and lattice constant of the MnCo-based metal oxide electromagnetic wave absorbing materials prepared in Examples 1 to 3 and Comparative Example 1.2.05 Co 0.91 The contents of O4 were 98.89wt.%, 99.00wt.%, 98.12wt.% and 99.99% respectively. 2.05 Co 0.91 O4 will not affect the significant change of the phase, while Mn after quenching 2.05 Co 0.91 The unit cell parameters of O4 (a, b, c in the table are the unit cell axis lengths in three directions, and V represents the size of the unit cell) have increased significantly, indicating that a large amount of lattice tensile strain can be induced in the sample through quenching treatment.

[0051] Table 1 Phase content and lattice constant of MnCo-based metal oxide electromagnetic wave absorbing materials prepared in Examples 1 to 3 and Comparative Example 1

[0052]

[0053] (II) Morphology Analysis: In addition, in order to illustrate the effect of changing the quenching medium on the surface morphology of the MnCo-based oxide, the electromagnetic wave absorbing materials prepared in Examples 1 to 3 and Comparative Example 1 were observed under a transmission electron microscope (TEM). The results are as follows: Figure 2 As shown, it can be observed that there is no significant difference in morphology between Comparative Example 1 and Examples 1 to 3. The MnCo-based metal oxides prepared in Comparative Example 1 and Examples 1 to 3 are all composed of nanospheres with a diameter of about 200nm and nanowires with a length of about 300nm. These findings further prove that quenching does not affect the Mn 2.05 Co 0.91 The process of O4 crystal growth is analyzed to determine whether the change in absorption performance is caused by the introduced strain.

[0054] (III) Analysis of wave absorption performance: The MnCo-based metal oxide electromagnetic wave absorbing materials prepared in Comparative Example 1 and Examples 1 to 3 were mixed with paraffin wax in a mass ratio of 33.3%:66.7% and pressed into ring-shaped absorber samples (D) of different thicknesses (2.0 to 2.5 mm). 外 =(7.00)mm,d 内 =(3.04)mm), and the electromagnetic wave absorption performance was tested. The results are as follows Figure 3 As shown in the figure, it can be seen that a Mn 2.05 Co 0.91The O4 metal oxide electromagnetic wave absorbing material exhibits extraordinary absorption capacity. With a thickness of only 2.47 mm, a relatively wide EAB of 7.52 GHz was observed. In contrast, the narrowest EAB was observed in Comparative Example 1, and relatively narrow EAB was observed in Examples 2 and 3, and the electromagnetic wave absorption performance was not high. 2.05 Co 0.91 O4 absorber samples were compared and the EAB value was observed. It was found that the Mn 2.05 Co 0.91 O4 has a broader EAB than the quenched sample, highlighting the strong correlation between quenching and introduced strain.

[0055] In summary, the present invention optimizes the dielectric properties of MnCo-based metal oxides by changing the quenching medium, customizes the lattice strain of the MnCo-based metal oxides, induces the generation of unpaired electrons, and finally adjusts the electromagnetic wave absorption performance, which is of great significance to the further development and wide application of MnCo-based metal oxide absorbing materials.

[0056] The above description of the embodiments is to facilitate the understanding and use of the invention by those skilled in the art. 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 work. Therefore, the present invention is not limited to the above embodiments, and improvements and modifications made by those skilled in the art based on the disclosure of the present invention without departing from the scope of the present invention should be within the scope of protection of the present invention.

Claims

1. A MnCo-based metal oxide electromagnetic wave absorbing material, characterized in that: The composition of the MnCo-based metal oxide is Mn 2.05 Co 0.91 O4.

2. The method for preparing a MnCo-based metal oxide electromagnetic wave absorbing material according to claim 1, characterized in that: The preparation method comprises the following steps: S1. Cobalt source, manganese source, urea and ammonium persulfate are mixed according to the chemical formula Mn 2.05 Co 0.91 The raw materials are prepared in a molar ratio of 0.04; the raw materials are fully stirred in deionized water to obtain a metal salt solution; S2. subjecting the obtained metal salt solution to a hydrothermal reaction to obtain a precursor solution; S3. The obtained precursor solution is centrifuged and washed, and the obtained precipitate is dried and ground to obtain a precursor metal oxide powder; S4. The obtained precursor metal oxide powder is calcined and quenched to obtain a metal oxide powder, namely, a MnCo-based metal oxide electromagnetic wave absorbing material.

3. The method for preparing a MnCo-based metal oxide electromagnetic wave absorbing material according to claim 2, characterized in that: In step S1, the cobalt source is cobalt nitrate hexahydrate with a purity of not less than 99.9%, the manganese source is manganese sulfate monohydrate with a purity of not less than 99.9%, and the purities of urea and ammonium persulfate are both not less than 99.9%; the molar ratio of the total amount of metal ions in the metal salt solution: urea: ammonium persulfate is 5:3:1; the total amount of metal ions in the metal salt solution is the total amount of cobalt in the cobalt source and manganese in the manganese source.

4. The method for preparing a MnCo-based metal oxide electromagnetic wave absorbing material according to claim 2, characterized in that: In step S1, the metal salt solution is fully stirred for 20 to 40 minutes.

5. The method for preparing a MnCo-based metal oxide electromagnetic wave absorbing material according to claim 2, characterized in that: In step S2, the hydrothermal reaction temperature is 160-180°C, and the reaction time is 180-240 minutes.

6. The method for preparing a MnCo-based metal oxide electromagnetic wave absorbing material according to claim 2, characterized in that: In step S3, the centrifugal washing is performed by washing alternately three times with deionized water and ethanol solution.

7. The method for preparing a MnCo-based metal oxide electromagnetic wave absorbing material according to claim 2, characterized in that: In step S3, the drying is preferably carried out in a vacuum drying oven for 12 to 14 hours at a temperature of 58 to 62°C.

8. The method for preparing a MnCo-based metal oxide electromagnetic wave absorbing material according to claim 2, characterized in that: In step S4, the calcination temperature is 250-400° C., and the calcination time is 2-4 hours.

9. The method for preparing a MnCo-based metal oxide electromagnetic wave absorbing material according to claim 2, characterized in that: In step S4, the quenching medium is any one of air, room temperature deionized water, and frozen deionized water; the quenching is: taking the calcined sample directly out of the highest temperature state and immersing it in a cooling medium.

10. The use of a MnCo-based metal oxide electromagnetic wave absorbing material as claimed in claim 1, characterized in that: The MnCo-based metal oxide electromagnetic wave absorption material is used for electromagnetic wave absorption in the field of artificial intelligence and 5G / 6G equipment.

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