A cerium-doped tin oxide absorbing material with a single crystal / polycrystalline two-phase structure and a preparation method thereof

Abstract

The present invention discloses a cerium-doped tin oxide absorbing material with a single crystal / polycrystalline two-phase structure and a preparation method thereof, belonging to the technical field of electromagnetic wave absorbing materials. The absorbing material comprises SnO2 single crystal columns and Ce-SnO2 polycrystalline nanoparticles, forming a heterojunction structure between the Ce-SnO2 polycrystalline nanoparticles and the SnO2 single crystal columns. The absorbing material is prepared by the following method: mixing and stirring a cerium source and a tin source, adding ammonia water dropwise to adjust the pH to 7-9, forming a precipitate, standing the mixture, washing, and drying; further grinding, calcining in an air atmosphere, and cooling to obtain the single crystal / polycrystalline two-phase cerium-doped tin oxide absorbing material. The single crystal / polycrystalline two-phase cerium-doped tin oxide absorbing material mainly relies on optimized impedance matching, enhanced interface polarization, and multiple reflections to attenuate and absorb electromagnetic waves, and has good application prospects in the field of wave absorption.

Description

Technical Field

[0001] The present invention relates to the technical field of electromagnetic wave absorbing materials, and in particular to a cerium-doped tin oxide absorbing material with a single crystal / polycrystalline two-phase structure and a preparation method thereof. Background Art

[0002] Electromagnetic pollution refers to the interference and harmful electromagnetic radiation caused by various natural and man-made electromagnetic waves. The rapid development of electronic and electrical equipment in the information age has led to an increase in electromagnetic pollution. Electromagnetic interference can affect the normal operation of electronic equipment and pose potential risks to human health. Preventing electromagnetic interference has become a key topic in electromagnetic wave research. High-performance microwave absorbing materials can effectively address this electromagnetic interference problem. However, the development of high-performance electromagnetic wave absorbing materials that simultaneously meet the four requirements of thinness, low density, wide frequency range, and strong absorption remains a significant challenge.

[0003] SnO2 is a common wide-bandgap semiconductor material with many special physical and chemical properties, good chemical stability and thermal stability. It is widely used in gas sensors, catalysts, varistors, etc. However, when single SnO2 is used as an electromagnetic wave absorption material, it has problems such as high density, weak absorption intensity, and narrow absorption band, which limits its application in the field of electromagnetic wave absorption.

[0004] Rare earth elements, due to their unique 4f outer electron structure, large atomic magnetic moment, and strong spin-orbit coupling, possess a wealth of optical, electrical, and magnetic properties. As "vitamins of industry," rare earth elements often have unexpected effects in material applications. Prior art includes Chinese patent publication No. CN101571504A, which discloses a SnO2 composite material doped with a rare earth element. Ce can be selected as the rare earth element. Ce doping can reduce the adsorption activation energy of chemical gases, significantly improving the sensitivity and response time of the SnO2 material and enhancing its gas-sensing properties. Chinese patent publication No. CN107486194A also discloses a cerium-loaded tin oxide composite microsphere photocatalyst. Cerium doping enhances the interaction between atoms in the catalyst, narrowing the band gap. The composite microspheres also exhibit excellent catalytic degradation effects under visible light conditions. However, the application of Ce-doped SnO2 materials in the field of microwave absorption requires further research. Summary of the Invention

[0005] The present invention provides a cerium-doped tin oxide absorbing material with a single crystal / polycrystalline two-phase structure. The absorbing material includes SnO2 single crystal columns and Ce-SnO2 polycrystalline nanoparticles forming a heterojunction structure. It mainly relies on optimized impedance matching, enhanced interface polarization and multiple reflections to attenuate and absorb electromagnetic waves, and has good application prospects in the field of absorbing waves.

[0006] The specific technical solutions adopted are as follows:

[0007] A cerium-doped tin oxide wave absorbing material with a single crystal / polycrystalline two-phase structure comprises SnO2 single crystal columns and Ce-SnO2 polycrystalline nanoparticles. A heterojunction structure is formed between the Ce-SnO2 polycrystalline nanoparticles and the SnO2 single crystal columns.

[0008] Preferably, the SnO2 single crystal column is in the shape of a cuboid, with a length of 0.5-2 μm and a cross-sectional area of 0.02-0.25 μm. 2 ; The particle size of Ce-SnO2 polycrystalline nanoparticles is 10-30nm.

[0009] The electrical conductivity of SnO2 lies between that of conductors and insulators. Doping SnO2 with an appropriate amount of Ce ions can increase and control the carrier concentration of SnO2, effectively regulating its dielectric properties. Furthermore, Ce doping leads to a higher number of defects and oxygen vacancies, which is important for enhancing the material's interfacial and ionic polarization, thereby improving its microwave absorption performance.

[0010] The cerium-doped tin oxide absorbing material with a single crystal / polycrystalline two-phase structure provided by the present invention forms a large number of heterogeneous interfaces between the single crystal columns and the nanoparticles, thereby enhancing interfacial polarization. In addition, Ce doping improves the overall electrical conductivity of the absorbing material, which is conducive to improving impedance matching. Enhanced interfacial polarization and good impedance matching are key factors in improving microwave absorption performance. In addition, the composite structure between the single crystal columns and the nanoparticles can cause multiple internal reflections of electromagnetic waves, which is conducive to repeated attenuation of electromagnetic waves and further improves the material's absorbing performance.

[0011] The present invention also provides a method for preparing the single crystal / polycrystalline two-phase structure cerium-doped tin oxide wave absorbing material, comprising the following steps:

[0012] (1) Dispersing a cerium source Ce(NO3)3·6H2O and a tin source SnCl4·5H2O in deionized water to obtain a mixed solution, stirring, adding ammonia water dropwise to adjust the pH to 7-9, forming a precipitate and allowing it to stand, washing, and then drying;

[0013] (2) Grinding the dried product of step (1), calcining in an air atmosphere, and cooling to obtain the cerium-doped tin oxide absorbing material having a single crystal / polycrystalline two-phase structure.

[0014] The present invention utilizes a co-precipitation method, uses Ce(NO3)3·6H2O as a cerium source, and SnCl4·5H2O as a tin source, to form a doping environment under the action of ammonia water, and in particular, needs to regulate the pH of the system to be 7-9 to obtain cerium-doped tin hydroxide, and then undergoes a further calcination process to form the cerium-doped tin oxide absorbing material with a single crystal / polycrystalline two-phase structure.

[0015] Preferably, in the mixed solution, Ce 3+ and Sn 4+ The molar ratio is 1:12-100.

[0016] Further preferably, in the mixed solution, Ce 3+ and Sn 4+ The molar ratio of 1:12-35 is 1:12-35. The single crystal / polycrystalline two-phase structure cerium-doped tin oxide absorbing material prepared within the above preferred range has better performance.

[0017] Preferably, in the mixed solution, the ratio of Ce(NO3)3·6H2O to deionized water is 1-10 mmol:100 mL.

[0018] Preferably, the stirring is carried out at a speed of 300 to 500 r / min.

[0019] Preferably, in step (1), the standing time is 18-48 hours.

[0020] The calcination step can convert the cerium-doped tin hydroxide obtained in step (1) into an oxide. Preferably, the calcination conditions are: a heating rate of 4 to 10°C / min, a calcination temperature of 400 to 700°C, and a calcination time of 2 to 4 hours. If the calcination temperature is too high, the single crystal pillars will be destroyed, while if the calcination temperature is too low, no single crystal pillars will be formed. Under the above preferred calcination conditions, the rapid growth of grains is conducive to the formation of SnO2 single crystal pillars and Ce-SnO2 polycrystalline nanoparticle heterojunction structures.

[0021] The present invention also provides application of the cerium-doped tin oxide wave-absorbing material with a single crystal / polycrystalline two-phase structure in a wave-absorbing device.

[0022] Preferably, the surface of the absorbing device is coated with an absorbing layer, and the absorbing material in the absorbing layer includes the cerium-doped tin oxide absorbing material with a single crystal / polycrystalline two-phase structure.

[0023] Compared with the prior art, the present invention has the following beneficial effects:

[0024] (1) The present invention prepares an absorbing material having a two-phase structure of SnO2 single crystal columns and Ce-SnO2 polycrystalline nanoparticles by doping Ce into SnO2 using a specific preparation method. The preparation method is simple and is conducive to large-scale application.

[0025] (2) The method of the present invention is easy to control. The length and cross-sectional dimensions of the obtained SnO2 single crystal column can be changed by adjusting the input amount of cerium source. Increasing the input amount of cerium source can improve the overall dielectric parameters of the material. At the same time, increasing the input amount of cerium source can optimize the impedance matching of the material, thereby improving the overall absorption performance of the material.

[0026] (3) The present invention adjusts the carrier concentration of SnO2 by doping with Ce. During the doping process, Ce ions replace Sn ions, generating a large number of oxygen vacancy defects on the surface and inside of the material, which will cause electromagnetic waves to be repeatedly refracted on the surface and inside of the material, which is beneficial to the overall loss of electromagnetic waves by the material.

[0027] (4) The cerium-doped tin oxide absorbing material with a single crystal / polycrystalline two-phase structure provided by the present invention forms a large number of heterogeneous interfaces between the single crystal columns and the nanoparticles, thereby enhancing the interface polarization. In addition, Ce doping improves the overall conductivity of the absorbing material, which is beneficial to improving impedance matching. Enhanced interface polarization and good impedance matching are key factors in improving microwave absorption performance. In addition, the composite structure between the single crystal columns and the nanoparticles can cause multiple reflections of electromagnetic waves inside, which is beneficial to repeatedly attenuate electromagnetic waves and further improve the absorbing performance of the material. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 This is an SEM image of the cerium-doped tin oxide absorbing material with a single crystal / polycrystalline two-phase structure in Example 1.

[0029] Figure 2 This is a TEM morphology image of the cerium-doped tin oxide absorbing material with a single crystal / polycrystalline two-phase structure in Example 1.

[0030] Figure 3 This is the TEM diffraction pattern of the cerium-doped tin oxide absorbing material with a single crystal / polycrystalline two-phase structure in Example 1.

[0031] Figure 4 This is the element distribution diagram of the cerium-doped tin oxide absorbing material with a single crystal / polycrystalline two-phase structure in Example 1, wherein h1 is the morphology diagram of the single crystal column, h2 is the Sn element distribution diagram in the single crystal column, h3 is the O element distribution diagram in the single crystal column, h4 is the Ce element distribution diagram in the single crystal column, i1 is the morphology diagram of the nanoparticles, i2 is the Sn element distribution diagram in the nanoparticles, i3 is the O element distribution diagram in the nanoparticles, and i4 is the Ce element distribution diagram in the nanoparticles.

[0032] Figure 5 1 is the XRD pattern of the absorbing materials prepared in Examples 1-3 and Comparative Example 1.

[0033] Figure 6 This is a dielectric constant curve of the single crystal / polycrystalline two-phase structure cerium-doped tin oxide absorbing material in Example 1.

[0034] Figure 7 This is a graph showing the magnetic permeability of the cerium-doped tin oxide absorbing material with a single crystal / polycrystalline two-phase structure in Example 1.

[0035] Figure 8This is the optimal reflection loss RL diagram of the single crystal / polycrystalline two-phase structure cerium-doped tin oxide absorbing material in Example 1. DETAILED DESCRIPTION

[0036] The present invention will be further described below in conjunction with the examples and accompanying drawings. It should be understood that these examples are intended to illustrate the present invention only and are not intended to limit the scope of the invention. The operating methods in the following examples where no specific conditions are specified are generally performed under conventional conditions or as recommended by the manufacturer.

[0037] Example 1

[0038] (1) Ce(NO3)3·6H2O and SnCl4·5H2O were dispersed in 100 mL of deionized water at a molar ratio of 7:93 to form a solution with a total concentration of 1 mol / L. The solution was magnetically stirred at a rate of 400 r / min. Ammonia was added dropwise to adjust the pH to 9. After the precipitate formed, it was allowed to stand for 24 h, washed alternately with water and ethanol, and dried at 85°C for 6 h.

[0039] (2) The dried product was ground into powder, and calcined in a KSL-1750X muffle furnace at a calcination temperature of 500°C, a heating rate of 5°C / min, and calcined for 2 hours. The product was cooled in the furnace to finally produce the single crystal / polycrystalline two-phase structure of cerium-doped tin oxide absorbing material.

[0040] The absorbing material was characterized and the results were as follows Figure 1-5 As shown, Figure 1 and Figure 2 The results show that the absorbing material prepared in this embodiment includes rectangular nanorods and nanoparticles, and a heterojunction structure is formed between the nanorods and the nanoparticles. The cross-sectional area of the nanorods is about 0.2-0.25 μm. 2 , the length is about 1-2μm, and the size of the nanoparticles is 10-30nm, Figure 3 The array diffraction pattern shows that the nanorods are single crystal columns. Figure 4 Figures h1-h4, i1-i4 show that the single crystal columns are composed of Sn and O elements, and the nanoparticles are composed of Ce, Sn, and O elements; Figure 5 It shows that the composition of the absorbing material is Ce-doped SnO2.

[0041] The microwave absorption performance of the absorbing material mixed with paraffin was tested by vector network analyzer. When the filling amount of the absorbing material was 80wt.%, the results were as follows: Figure 6-8 As shown, Figure 6 The real part of the dielectric constant of the mixture is in the range of 14-20, and the imaginary part of the dielectric constant is in the range of 3-6. Figure 7 The real part of the magnetic permeability of the mixture is in the range of 1.0-1.1, and the imaginary part of the magnetic permeability is in the range of 0-0.2. Figure 8It shows that when the thickness is 1-2 mm, the optimal reflection loss of the mixture reaches -30 to -40 dB in the 2-18 GHz electromagnetic band, and the effective absorption bandwidth can reach 4.5-7 GHz.

[0042] Example 2

[0043] The preparation method of the single crystal / polycrystalline two-phase structure cerium-doped tin oxide absorbing material in Example 2 differs from that in Example 1 only in that the molar ratio of Ce(NO3)3·6H2O and SnCl4·5H2O is changed to 5:95; ammonia water is added dropwise to adjust the pH to 7; and the standing time is 18 hours.

[0044] In this embodiment, in the cerium-doped tin oxide absorbing material with a single crystal / polycrystalline two-phase structure, the length of the single crystal column is smaller than that in Example 1, and the cross-sectional area of the single crystal column is about 0.1-0.2 μm 2 , length is about 0.6-1.4 μm, and the size of polycrystalline nanoparticles is 10-30 nm;

[0045] The microwave absorption performance of the absorbing material was tested using a vector network analyzer. When the filling amount of the absorbing material was 80wt.% and the thickness was 1-2mm, the optimal reflection loss of the mixture in the 2-18GHz electromagnetic band reached -25 to -35dB, and the effective absorption bandwidth could reach 3-5GHz.

[0046] Example 3

[0047] The preparation method of the single crystal / polycrystalline two-phase structure cerium-doped tin oxide absorbing material in Example 3 differs from that in Example 1 only in that the molar ratio of Ce(NO3)3·6H2O and SnCl4·5H2O is 3:97; the calcination conditions are: heating rate 6°C / min, calcination temperature 450°C, and calcination for 3 hours.

[0048] In this embodiment, in the cerium-doped tin oxide absorbing material with a single crystal / polycrystalline two-phase structure, the length of the single crystal column is smaller than that in Example 1, and the cross-sectional area of the single crystal column is about 0.02-0.1 μm 2 , length is about 0.6-1 μm, and the size of polycrystalline nanoparticles is 10-30 nm;

[0049] The microwave absorption performance of the obtained powder was tested by a vector network analyzer. When the filling amount of the absorbing material was 80wt.% and the thickness was 1-2mm, the optimal reflection loss of the mixture in the 2-18GHz electromagnetic band reached -35 to -50dB, and the effective absorption bandwidth could reach 4-6GHz.

[0050] Comparative Example 1

[0051] In Comparative Example 1, the preparation method of the absorbing material is different from that of Example 1 only in that the molar ratio of Ce(NO3)3·6H2O and SnCl4·5H2O is changed to 9:91, and Ce(NO3)3·6H2O is not within the scope of the invention. 3+ and Sn 4+ When the molar ratio is in the range of 1:12-100, the microwave absorption performance of the sample is poor. When the filling amount of the absorbing material is 80wt.% and the thickness is 1-2mm, the optimal reflection loss of the mixture in the 2-18GHz electromagnetic band is only -15 to -22dB, and the effective absorption bandwidth is 2-3GHz.

[0052] Comparative Example 2

[0053] In Comparative Example 2, the preparation method of the absorbing material differs from that of Example 1 only in that the calcination temperature is changed to 800° C. The results show that the calcination temperature is too high and no single crystal columns are produced.

[0054] The embodiments described above provide a detailed description of the technical solutions of the present invention. It should be understood that the above are only specific embodiments of the present invention and are not intended to limit the present invention. Any modifications, supplements or similar substitutions made within the scope of the principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A cerium-doped tin oxide absorbing material with a single crystal / polycrystalline two-phase structure, characterized in that: It includes SnO2 single crystal columns and Ce-SnO2 polycrystalline nanoparticles, and a heterojunction structure is formed between the Ce-SnO2 polycrystalline nanoparticles and the SnO2 single crystal columns.

2. The single crystal / polycrystalline two-phase structure cerium-doped tin oxide absorbing material according to claim 1, characterized in that: The SnO2 single crystal column is rectangular, with a length of 0.5-2 μm and a cross-sectional area of 0.02-0.25 μm. 2 .

3. The single crystal / polycrystalline two-phase structure cerium-doped tin oxide absorbing material according to claim 1, characterized in that: The particle size of Ce-SnO2 polycrystalline nanoparticles is 10-30 nm.

4. The method for preparing the single crystal / polycrystalline two-phase structure cerium-doped tin oxide absorbing material according to any one of claims 1 to 3, characterized in that: The following steps are involved: (1) Disperse the cerium source Ce(NO3)3·6H2O and the tin source SnCl4·5H2O in deionized water to obtain a mixed solution, stir, add ammonia water dropwise to adjust the pH to 7-9, form a precipitate, let it stand, wash and dry; (2) grinding the dried product of step (1), calcining it in an air atmosphere, and cooling it to obtain the cerium-doped tin oxide absorbing material having a single crystal / polycrystalline two-phase structure; In the mixed solution, Ce 3+ and Sn 4+ The molar ratio is 1:12-100; The calcination conditions are: heating rate 4-10°C / min, calcination temperature 400-700°C, and calcination 2-4 h.

5. The method for preparing the single crystal / polycrystalline two-phase structure cerium-doped tin oxide absorbing material according to claim 4, characterized in that: In the mixed solution, the ratio of Ce(NO3)3·6H2O to deionized water is 1-10 mmol: 100 mL.

6. The method for preparing the single crystal / polycrystalline two-phase structure cerium-doped tin oxide absorbing material according to claim 4, characterized in that: In step (1), the standing time is 18-48 h.

7. Use of the cerium-doped tin oxide absorbing material with a single crystal / polycrystalline two-phase structure according to any one of claims 1 to 3 in an absorbing device.

8. Use of the single crystal / polycrystalline two-phase structured cerium-doped tin oxide absorbing material in an absorbing device according to claim 7, characterized in that: The surface of the wave absorbing device is coated with a wave absorbing layer, and the wave absorbing material in the wave absorbing layer includes the cerium-doped tin oxide wave absorbing material with a single crystal / polycrystalline two-phase structure.

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