Two-dimensional perovskite structure oxide / carbon composite wave-absorbing material and preparation method thereof

Abstract

The invention discloses a preparation method of a two-dimensional perovskite structure oxide / carbon composite wave-absorbing material, which comprises the following steps: firstly, preparing a precursor containing La (NO3) 3.6 H2O, Fe (NO3) 3.9 H2O and a carbon source; then, dissolving the precursor in deionized water, and adding NaCl to prepare a precursor solution; and then, drying the solution in a drying oven until the product is completely dried and has a chapping phenomenon. And grinding and screening the dried product, calcining, and cooling along with the furnace. And respectively washing the calcined sample with deionized water and ethanol, drying again, and carrying out secondary grinding and screening. And finally, further drying the treated product in a drying oven, and cooling along with the furnace. The material shows excellent performance in the aspects of thinness, weight, absorption frequency band width and absorption strength, and effectively solves the problems of poor impedance matching and narrow frequency band of a traditional material, single La (NO3) 3 and a carbon absorbent.

Description

Technical Field

[0001] The present invention belongs to the technical field of absorbing materials, and in particular relates to a two-dimensional perovskite structure oxide / carbon composite absorbing material and a preparation method thereof. Background Art

[0002] As electronic devices gradually develop towards higher frequencies and smaller sizes, electromagnetic interference (EMI) is becoming increasingly prominent. While traditional microwave absorbing materials, such as ferrites and carbon-based composites, can address EMI to a certain extent, their application has several limitations: these materials are typically thick (typically >3mm), have a narrow effective absorption bandwidth (<4GHz, unable to cover the X-band), and are relatively complex to prepare.

[0003] Existing research reveals that perovskite oxides, due to their unique magnetoelectric coupling properties, show potential for application in microwave absorption. However, as single-phase materials, perovskite oxides exhibit low dielectric loss and insufficient magnetic loss capacity, which greatly limits their effectiveness when used alone for electromagnetic interference suppression. Furthermore, compared with traditional carbon-based absorbers, current perovskite oxide-based absorbers often suffer from poor impedance matching and a narrow effective absorption band. Therefore, further research on these materials is particularly important to overcome these shortcomings and expand their potential for application in high-frequency electromagnetic interference suppression. Summary of the Invention

[0004] The purpose of the embodiments of the present invention is to provide a two-dimensional perovskite structure oxide / carbon composite absorbing material to solve the problems of poor impedance matching and narrow bandwidth of single Fe(NO3)3 absorber and C absorber, and to achieve lightweight and wide-band microwave absorption.

[0005] A second object of the present invention is to provide a method for preparing a two-dimensional perovskite structured oxide / carbon composite absorbing material.

[0006] To solve the above technical problems, the technical solution adopted by the present invention is a method for preparing a two-dimensional perovskite structure oxide / carbon composite absorbing material, which is specifically carried out according to the following types:

[0007] S1. Preparing a precursor; the precursor includes La(NO3)3·6H2O, Fe(NO3)3·9H2O and a carbon source;

[0008] S2. Dissolve the precursor in deionized water and add NaCl to prepare a precursor solution;

[0009] S3. Place the precursor solution in an oven and dry it until the product is cracked and has no trace of moisture.

[0010] S4, grinding and sieving the dried product;

[0011] S5, calcining the sieved product and then cooling it in the furnace;

[0012] S6. Wash the calcined sample with deionized water and ethanol in sequence and dry it; then grind it a second time and sieve it;

[0013] S7. Drying in an oven and cooling with the oven to obtain a two-dimensional perovskite structure oxide / carbon composite absorbing material.

[0014] Furthermore, the molar ratio of La(NO3)3·6H2O, Fe(NO3)3·9H2O and carbon source in S1 is (0.75-1):1:1.

[0015] Furthermore, the carbon source includes one or more combinations of sucrose, glucose, fullerene, graphene, and biomass carbon.

[0016] Furthermore, in S2, after the precursor is dissolved in deionized water, La 3+ Concentration is 0.125~0.167mol·L -1 ; The mass ratio of NaCl to deionized water is (36~40):100.

[0017] Furthermore, in S4 and S6, sieving is performed using a sieve of 200 to 300 meshes.

[0018] Furthermore, the calcination parameters of S5 are: 5-10°C·min under inert atmosphere -1 The temperature is raised to 550-600°C at a heating rate and calcined for 2-2.5 hours.

[0019] Furthermore, it is prepared by the above-mentioned method for preparing a two-dimensional perovskite structure oxide / carbon composite absorbing material.

[0020] Compared to existing technologies, the present invention offers the advantage of overcoming the performance limitations of traditional absorbing materials by engineering defects in A-site cations and combining them with carbon materials. This method achieves a thinner, lighter-weight absorbing material with a wider absorption bandwidth and enhanced absorption capacity. Specifically, by precisely controlling the defect concentration of A-site cations and effectively combining them with the carbon material, the electromagnetic parameter matching within the material is improved, thereby optimizing the absorbing performance.

[0021] Furthermore, the present invention not only solves the impedance mismatch problem between single Fe(NO3)3 absorbers and carbon-based absorbers, but also broadens the absorption bandwidth. The two-dimensional structural design helps to reduce the material's interfacial polarization loss and enhance the electron scattering effect, further enhancing its absorption of electromagnetic waves. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. 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 paying any creative work.

[0023] Figure 1 is the XRD spectrum of the composite absorbing material prepared in Examples 1 to 5 of the present invention;

[0024] Figure 2 The SEM images of the composite absorbing materials prepared in Examples 1 to 5 of the present invention are shown in FIG. 1 , wherein (a) is LaFeO3 / C, and (b) is La 0.9 FeO3 / C, (c) is La 0.85 FeO3 / C, (d) is La 0.8 FeO3 / C, (e) is La 0.75 FeO3 / C;

[0025] Figure 3 is the reflection loss value of the composite absorbing material prepared in Example 4 of the present invention at different thicknesses;

[0026] Figure 4 is the reflection loss value of the composite absorbing material prepared in Comparative Example 1 of the present invention at different thicknesses;

[0027] Figure 5 is the reflection loss value of the composite absorbing material prepared in Comparative Example 2 of the present invention at different thicknesses;

[0028] Figure 6 is the reflection loss value of the composite absorbing material prepared in Comparative Example 3 of the present invention at different thicknesses;

[0029] Figure 7 is the reflection loss value of the composite absorbing material prepared in Comparative Example 4 of the present invention at different thicknesses;

[0030] Figure 8 is the reflection loss value of the composite absorbing material prepared in Comparative Example 5 of the present invention at different thicknesses;

[0031] Figure 9is the reflection loss value of the composite absorbing material prepared in Comparative Example 6 of the present invention at different thicknesses;

[0032] Figure 10 : is the reflection loss value of the composite absorbing material prepared in Comparative Example 7 of the present invention at different thicknesses. DETAILED DESCRIPTION

[0033] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0034] This embodiment provides a two-dimensional perovskite structure oxide / carbon composite absorbing material, specifically a two-dimensional perovskite structure oxide / carbon composite absorbing material with A-site vacancy regulation; through the A-site cation defect engineering and carbon material composite, it breaks through the performance bottleneck of traditional materials and achieves lightweight (thickness <3mm) and wide-band (covering the X-band) microwave absorption.

[0035] In some specific embodiments, the absorbing material is prepared by the following steps:

[0036] Step S1, weighing: La(NO3)3·6H2O, Fe(NO3)3·9H2O and a carbon source are weighed according to a molar ratio of (x:1:1) to (1:1:1), where 0.75≤x≤1, to obtain a precursor.

[0037] In some possible embodiments, the carbon source includes one or more combinations of glucose, graphene, and fullerene.

[0038] In this embodiment, the A-site vacancy regulation process is specifically three interrelated processes: first, the lattice distortion and local electron reconstruction process, the A-site cation (such as La 3+ ) causes lattice contraction (XRD refinement shows that the unit cell volume is reduced), forming local lattice distortion (Jahn-Teller effect). This structural change forms more defect sites (such as oxygen vacancies); the oxygen vacancies (V0) induced by the A-site defect and the B-site cations (such as Fe 3+ / Fe 4+) forms Fe-V0 dipole pairs, which enhances polarization losses. Secondly, the two-dimensional carbon network guides the conductive path, inducing eddy current losses by providing an efficient conductive path and extending the electromagnetic wave propagation path, thereby improving the electromagnetic shielding performance of the material. Finally, the complex dielectric constant (ε=ε'-jε”) and complex magnetic permeability (μ=μ'-jμ”) are adjusted to make the normalized input impedance (Zin) closer to the free space impedance (Z0), reducing surface reflections and improving electromagnetic wave absorption efficiency.

[0039] Step S2, dissolution: The weighed precursors were fully mixed and dissolved in deionized water, and the La 3+ Concentration is 0.125-0.167 mol·L -1 , then add NaCl and stir for 30-40 minutes; wherein the mass ratio of NaCl to deionized water is 36gNaCl / 100g~40gNaCl / 100g.

[0040] In this embodiment, in the perovskite structure, La 3+ The proper doping of ions is crucial to optimizing material properties. 3+ When the ion content is appropriate, the integrity of the perovskite structure can be significantly improved, and oxygen vacancy defects and lattice distortion can be effectively reduced, thereby enhancing the polarization loss and impedance matching characteristics of the material. 3+ Excessive ion doping will inhibit the effective doping of other elements (such as C), hinder the formation of two-dimensional structure composite materials, and limit the expansion of multifunctional properties of materials. 3+ Although too little ion doping can improve the dielectric properties to a certain extent, it can easily lead to increased structural inhomogeneity due to the presence of impurities, thereby affecting the overall performance of the material.

[0041] In this embodiment, NaCl particles (cubes, with a side length of about 400 μm) serve as physical templates to form the precursor solution (containing La) during the drying process. 3+ 、Fe 3+ The precursor evenly coats the NaCl surface. After high-temperature calcination, the carbon source carbonizes to form a two-dimensional amorphous carbon matrix, within which the LaFeO3 nanoparticles are embedded. Finally, the NaCl is dissolved by water washing, yielding a LaFeO3 / C composite material with a two-dimensional lamellar structure.

[0042] Furthermore, the cubic morphology of NaCl is transformed into a two-dimensional carbon network through a "coating-carbonization-dissolution" process. Its high specific surface area and open structure facilitate multiple reflections and scattering of electromagnetic waves. During the subsequent calcination process, the NaCl template physically isolates the LaFeO3 nanoparticles, suppressing their aggregation and ensuring their uniform dispersion within the carbon matrix.

[0043] Furthermore, the close contact between the carbon matrix and the nanoparticles enhances interfacial polarization (Maxwell-Wagner effect), further increasing dielectric loss. The water solubility of NaCl also allows for its removal by simple washing in the later stages of synthesis, avoiding the introduction of impurities while preserving the intact two-dimensional porous structure. The pore structure formed by the dissolution of NaCl increases the specific surface area of the material, providing more reflection paths for electromagnetic waves and prolonging energy dissipation time.

[0044] Step S3, drying: After stirring, the precursor solution is placed in an oven and dried for 15-16 hours; specifically:

[0045] Pour the evenly stirred precursor into a clean stainless steel plate and place it in a fume hood. After the mixed solution becomes viscous, place the stainless steel plate containing the product in an oven at 85-95°C to form a NaCl template-loaded precursor. Take it out after the product cracks and there is no trace of moisture.

[0046] Step S4, grinding: the dried product was manually ground using an agate mortar and then sieved using a 200-300 mesh sieve;

[0047] Step S5: Calcination: The sieved product is heated to 550-600°C and kept at this temperature for 2-2.5 hours, and then cooled in the furnace; specifically:

[0048] First, the sieved NaCl template-loaded precursor is placed in a clean ceramic crucible and calcined in a high-temperature tube furnace at 5-10°C / min in an inert gas atmosphere such as argon or nitrogen. -1 The heating rate is increased to 550-600℃;

[0049] Step S6, washing: washing the calcined sample with deionized water and ethanol in sequence;

[0050] The product of S5 was washed with deionized water and ethanol several times in sequence and then dried; the obtained La x The FeO3 / C absorbent was completely dispersed and then sieved with a 200-mesh sieve.

[0051] Step S7, drying: finally drying in an oven at 55-60°C for 23-24 hours. Then cooling in the oven to obtain La x FeO3 / C absorbent.

[0052] Example 1

[0053] S1. Weighing: Weigh 1 mmol of La(NO3)3·6H2O, 1 mmol of Fe(NO3)3·9H2O, and 1 mmol of sucrose in sequence;

[0054] S2, fully mix the weighed La(NO3)3·6H2O, Fe(NO3)3·9H2O and carbon source and dissolve them in deionized water. 3+ The concentration is 0.167 mol·L -1 , the mass ratio of NaCl to deionized water is 38:100;

[0055] S3. Drying: Pour the stirred precursor into a clean stainless steel plate and place it in a fume hood. After the mixed solution becomes viscous, place the stainless steel plate containing the product in a 90°C oven and dry it for 15 hours to form a NaCl template-loaded precursor.

[0056] S4, grinding: the dried product was manually ground using an agate mortar and pestle, and then sieved using a 200-mesh sieve;

[0057] S5. Calcination: Place the sieved NaCl template-loaded precursor into a clean ceramic crucible and calcine it in a high-temperature tube furnace under N2 atmosphere at 5°C·min -1 The temperature was raised to 600 °C at a heating rate of 1000 °C and calcined for 2 h.

[0058] S6, washing: making La x After the FeO3 / C absorbent is applied, it is washed with deionized water and ethanol several times in sequence and then dried;

[0059] S7, use an agate mortar to grind manually for the second time, and completely disperse the obtained LaFeO3 / C absorbent, and then sieve it with a 200 mesh sieve. Finally, dry it in a 55℃ oven for 23 hours. Then cool it in the oven to obtain LaFeO3 / C. x FeO3 / C absorbent.

[0060] Example 2

[0061] S1. Weighing: Weigh 0.9 mmol of La(NO3)3·6H2O, 1 mmol of Fe(NO3)3·9H2O, and 1 mmol of fullerene in sequence;

[0062] S2, fully mix the weighed La(NO3)3·6H2O, Fe(NO3)3·9H2O and carbon source and dissolve them in deionized water. 3+ The concentration is 0.146 mol·L -1 , where the mass ratio of NaCl to deionized water is 36:100;

[0063] S3. Drying: Pour the stirred precursor into a clean stainless steel plate and place it in a fume hood. After the mixed solution becomes viscous, place the stainless steel plate containing the product in a 90°C oven and dry it for 16 hours to form a NaCl template-loaded precursor.

[0064] S4, grinding: the dried product was manually ground using an agate mortar and pestle, and then sieved using a 200-mesh sieve;

[0065] S5. Calcination: Place the sieved NaCl template-loaded precursor into a clean ceramic crucible and calcine it in a high-temperature tube furnace under an Ar atmosphere at 6°C min -1 The temperature was raised to 590°C at a heating rate of 1.5°C and calcined for 2.1h.

[0066] S6, washing: making La x After the FeO3 / C absorbent is applied, it is washed with deionized water and ethanol several times in sequence and then dried;

[0067] S7, use agate mortar to grind manually for the second time, and make the obtained La 0.9 The FeO3 / C absorbent was completely dispersed and then sieved with a 200-mesh sieve. Finally, it was dried in an oven at 56°C for 24 hours. Then it was cooled in the oven to obtain La 0.9 FeO3 / C absorbent.

[0068] Example 3

[0069] S1. Weighing: Weigh 0.85 mmol of La(NO3)3·6H2O, 1 mmol of Fe(NO3)3·9H2O, and 1 mmol of glucose in sequence;

[0070] S2, fully mix the weighed La(NO3)3·6H2O, Fe(NO3)3·9H2O and carbon source and dissolve them in deionized water. 3+ The concentration is 0.125 mol·L -1 ; Among them, the mass ratio of NaCl to deionized water is 40:100;

[0071] S3. Drying: Pour the stirred precursor into a clean stainless steel plate and place it in a fume hood. After the mixed solution becomes viscous, place the stainless steel plate containing the product in an 85°C oven and dry it for 16 hours to form a NaCl template-loaded precursor.

[0072] S4, grinding: the dried product was manually ground using an agate mortar and pestle, and then sieved using a 200-mesh sieve;

[0073] S5. Calcination: Place the sieved NaCl template-loaded precursor into a clean ceramic crucible and calcine it in a high-temperature tube furnace under an Ar atmosphere at 7°C min -1 The temperature was raised to 580°C at a heating rate of 1.5°C and calcined for 2.2 h.

[0074] S6, washing: making La x After the FeO3 / C absorbent is applied, it is washed with deionized water and ethanol several times in sequence and then dried;

[0075] S7, use agate mortar to grind manually for the second time, and make the obtained La 0.85 The FeO3 / C absorbent was completely dispersed and then sieved with a 200-mesh sieve. Finally, it was dried in an oven at 57°C for 23 hours. Then it was cooled in the oven to obtain La 0.85 FeO3 / C absorbent.

[0076] Example 4

[0077] S1. Weighing: Weigh 0.8 mmol of La(NO3)3·6H2O, 1 mmol of Fe(NO3)3·9H2O, 0.5 mmol of sucrose, and 0.5 mmol of glucose in sequence;

[0078] S2, fully mix the weighed La(NO3)3·6H2O, Fe(NO3)3·9H2O and carbon source and dissolve them in deionized water. 3+ The concentration is 0.167 mol·L -1 , where the mass ratio of NaCl to deionized water is 40:100;

[0079] S3. Drying: Pour the stirred precursor into a clean stainless steel plate and place it in a fume hood. After the mixed solution becomes viscous, place the stainless steel plate containing the product in a 95°C oven and dry it for 16 hours to form a NaCl template-loaded precursor.

[0080] S4, grinding: the dried product was manually ground using an agate mortar and pestle, and then sieved using a 200-mesh sieve;

[0081] S5. Calcination: Place the sieved NaCl template-loaded precursor into a clean ceramic crucible and calcine it in a high-temperature tube furnace under a nitrogen atmosphere at 8°C·min -1 The temperature was raised to 570°C at a heating rate of 1.5°C and calcined for 2.3 h.

[0082] S6, washing: making La x After the FeO3 / C absorbent is applied, it is washed with deionized water and ethanol several times in sequence and then dried;

[0083] S7, use agate mortar to grind manually for the second time, and make the obtained La 0.8 The FeO3 / C absorbent was completely dispersed and then sieved with a 200-mesh sieve. Finally, it was dried in an oven at 58°C for 24 hours. Then it was cooled in the oven to obtain La 0.8 FeO3 / C absorbent.

[0084] The reflection loss RL of the material is calculated according to the transmission line theory formula, and La is explained by analyzing the reflection loss of the material. x The overall absorption performance of FeO3 / C material for electromagnetic waves. x The reflection loss of FeO3 / C (x=0.8) is as follows Figure 3 As shown, at a relatively thin thickness, the minimum reflection loss value exceeds -40dB, the maximum bandwidth is close to 7.9GHz (2.4mm), and the wave absorption performance is excellent.

[0085] like Figure 1 The lattice constant of LaxFeO3 / C (x=1, 0.9, 0.85, 0.8, 0.75) does not change significantly, which is consistent with the main diffraction peaks of LaFeO3 standard PDF card at 22.6°, 32.3°, 39.6°, 46.3°, 52.3° and 57.6°, corresponding to the (100), (110), (111), (200), (210) and (211) crystal planes, respectively.

[0086] like Figure 2 (a) The gaps between LaFeO3 / C particles are unclear and there is a certain amount of agglomeration, but the performance is acceptable. Figure 2 (b)La 0.9 The SEM image of the FeO3 / C sample shows obvious interface gaps, forming a two-dimensional lamellar structure. Figure 2 (c)La 0.85 FeO3 / C, the gaps between the two-dimensional lamellar shapes formed are clearer and the lamellar surface is smoother. Figure 2 (d)La 0.8 An obvious two-dimensional lamellar structure can be observed in FeO3 / C. Figure 2 (e)La 0.75 A two-dimensional lamellar structure can be clearly observed in FeO3 / C.

[0087] Example 5

[0088] S1. Weighing: Weigh 0.75 mmol of La(NO3)3·6H2O, 1 mmol of Fe(NO3)3·9H2O, 0.5 mmol of graphene, and 0.5 mmol of sucrose in sequence;

[0089] S2, fully mix the weighed La(NO3)3·6H2O, Fe(NO3)3·9H2O and carbon source and dissolve them in deionized water. 3+ The concentration is 0.167 mol·L -1 , where the mass ratio of NaCl to deionized water is 40:100;

[0090] S3. Drying: Pour the stirred precursor into a clean stainless steel plate and place it in a fume hood. After the mixed solution becomes viscous, place the stainless steel plate containing the product in a 95°C oven and dry it for 16 hours to form a NaCl template-loaded precursor.

[0091] S4, grinding: the dried product was manually ground using an agate mortar and pestle, and then sieved using a 200-mesh sieve;

[0092] S5. Calcination: Place the sieved NaCl template-loaded precursor into a clean ceramic crucible and calcine it in a high-temperature tube furnace under a nitrogen atmosphere at 9°C·min -1 The temperature was raised to 560°C at a heating rate of 1.5°C and calcined for 2.4 h.

[0093] S6, washing: making La x After the FeO3 / C absorbent is applied, it is washed with deionized water and ethanol several times in sequence and then dried;

[0094] S7, use agate mortar to grind manually for the second time, and make the obtained La 0.75 The FeO3 / C absorbent was completely dispersed and then sieved with a 200-mesh sieve. Finally, it was dried in an oven at 59°C for 23 hours. Then it was cooled in the oven to obtain La 0.75 FeO3 / C absorbent.

[0095] Example 6

[0096] S1. Weighing: Weigh 0.75 mmol of La(NO3)3·6H2O, 1 mmol of Fe(NO3)3·9H2O, 0.5 mmol of fullerene, and 0.5 mmol of glucose in sequence;

[0097] S2, fully mix the weighed La(NO3)3·6H2O, Fe(NO3)3·9H2O and carbon source and dissolve them in deionized water. 3+ The concentration is 0.167 mol·L -1 , where the mass ratio of NaCl to deionized water is 40:100;

[0098] S3. Drying: Pour the stirred precursor into a clean stainless steel plate and place it in a fume hood. After the mixed solution becomes viscous, place the stainless steel plate containing the product in a 95°C oven and dry it for 16 hours to form a NaCl template-loaded precursor.

[0099] S4, grinding: the dried product was manually ground using an agate mortar and pestle, and then sieved using a 200-mesh sieve;

[0100] S5. Calcination: Place the sieved NaCl template-loaded precursor into a clean ceramic crucible and calcine it in a high-temperature tube furnace under a nitrogen atmosphere at 10°C / min. -1 The temperature was raised to 550 °C at a heating rate of 1000 ℃ and calcined for 2.5 h.

[0101] S6, washing: making La x After the FeO3 / C absorbent is applied, it is washed with deionized water and ethanol several times in sequence and then dried;

[0102] S7, use agate mortar to grind manually for the second time, and make the obtained La 0.75 The FeO3 / C absorbent was completely dispersed and then sieved with a 200-mesh sieve. Finally, it was dried in an oven at 60°C for 24 hours. Then it was cooled in the oven to obtain La 0.75 FeO3 / C absorbent.

[0103] Comparative Example 1

[0104] The difference from Example 4 is that the amount of La(NO3)3·6H2O in S1 is 2 mmol; the remaining steps are the same as Example 4.

[0105] like Figure 4 As shown, the maximum absorption peak of Comparative Example 1 occurs when the matching thickness is 3.4 mm, and the corresponding reflection loss is -15.5 dB. This absorption performance is relatively weak and significantly lower than that of the embodiment.

[0106] Comparative Example 2

[0107] The difference from Example 4 is that the amount of La(NO3)3·6H2O in S1 is 0.1 mmol; the remaining steps are the same as those in Example 4.

[0108] according to Figure 5 As described above, the absorbing material in Comparative Example 2 reaches the maximum absorption peak when the thickness is 5.9 mm, and its reflection loss value is -13.4 dB, which is relatively poor compared with the embodiment.

[0109] Comparative Example 3

[0110] The difference from Example 4 is that NaCl is not introduced into S2, and the remaining steps are the same as those in Example 4.

[0111] like Figure 6 As shown, the overall reflection loss of the absorbing material prepared in Comparative Example 3 exceeded -10 dB under all 10 matching thickness conditions, indicating that the material exhibited poor absorbing performance. This result suggests that compared with the examples, its efficiency in absorbing electromagnetic waves is lower and fails to achieve the ideal absorbing effect.

[0112] Comparative Example 4

[0113] The difference from Example 4 is that in S2, La is controlled 3+ The concentration is 1.25 mol·L -1 , the remaining steps are the same as those in Example 4.

[0114] according to Figure 7 As shown, when the simulated thickness of the absorbing material prepared in Comparative Example 4 exceeds 6.5 mm, the overall reflection loss is higher than -10 dB in 10 tests with different matching thicknesses. The absorbing performance of the material prepared in Comparative Example 4 is not ideal, and the overall absorbing effect is poor.

[0115] Comparative Example 5

[0116] The difference from Example 4 is that in S2, La is controlled 3+ The concentration is 0.025 mol·L -1 , the remaining steps are the same as those in Example 4.

[0117] like Figure 8 As shown, the reflection loss of the absorbing material prepared in Comparative Example 5 under 10 different matching thickness conditions generally failed to exceed -10dB. When the matching thickness was 2.9mm, the material showed the maximum absorption peak, with a reflection loss peak of only -12.7dB, indicating that its absorbing performance was relatively limited and its overall performance was poor.

[0118] Comparative Example 6

[0119] The difference from Example 4 is that the calcination temperature in S5 is 1000° C., and the remaining steps are the same as Example 4.

[0120] like Figure 9 As shown, the reflection loss values of the absorbing material prepared in Comparative Example 6 at 10 different matching thicknesses are all lower than -10dB. The maximum absorption peaks appear only when the thickness is 3.1mm and 3.2mm, and the reflection losses are -12.9dB respectively, indicating that its absorbing performance is relatively weak and the overall absorption characteristics are poor.

[0121] Comparative Example 7

[0122] The difference from Example 4 is that the calcination temperature in S5 is 400° C., and the remaining steps are the same as Example 1.

[0123] like Figure 10 As shown, when the matching thickness of the absorbing material prepared in Comparative Example 7 is 3.5 mm, its minimum reflection loss is -24.8 dB and its effective absorption bandwidth is 5.1 GHz, which is significantly lower than that of the embodiment, indicating that its absorbing performance is relatively poor.

[0124] Each embodiment in this specification is described in a related manner. Similar parts between the various embodiments can be referred to in conjunction with each other. Each embodiment focuses on the differences between the other embodiments. In particular, the system embodiment is generally similar to the method embodiment, so the description is relatively simple. For related parts, refer to the description of the method embodiment.

[0125] The above description is only a preferred embodiment of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention are included in the scope of protection of the present invention.

Claims

1. A method for preparing a two-dimensional perovskite structure oxide / carbon composite absorbing material, characterized in that: Specifically according to the following types: S1. Preparing a precursor; the precursor includes La(NO3)3·6H2O, Fe(NO3)3·9H2O and a carbon source; S2. Dissolve the precursor in deionized water and add NaCl to prepare a precursor solution; S3. Place the precursor solution in an oven and dry it until the product is cracked and has no trace of moisture. S4, grinding and sieving the dried product; S5, calcining the sieved product and then cooling it in the furnace; S6. Wash the calcined sample with deionized water and ethanol in sequence and dry it; then grind it a second time and sieve it; S7. Drying in an oven and cooling with the oven to obtain a two-dimensional perovskite structure oxide / carbon composite absorbing material.

2. The method for preparing a two-dimensional perovskite structure oxide / carbon composite absorbing material according to claim 1, characterized in that: The molar ratio of La(NO3)3·6H2O, Fe(NO3)3·9H2O and carbon source described in S1 is (0.75~1):1:

1.

3. The method for preparing a two-dimensional perovskite structure oxide / carbon composite absorbing material according to claim 2, characterized in that: The carbon source includes one or more combinations of sucrose, glucose, fullerene, graphene, and biomass carbon.

4. The method for preparing a two-dimensional perovskite structure oxide / carbon composite absorbing material according to claim 1, characterized in that: In the S2, the precursor is dissolved in deionized water, La 3+ Concentration is 0.125~0.167mol·L -1 ; The mass ratio of NaCl to deionized water is (36~40):

100.

5. The method for preparing a two-dimensional perovskite structure oxide / carbon composite absorbing material according to claim 1, characterized in that: In the above-mentioned S4 and S6, the sieve is sieved using a sieve of 200 to 300 meshes.

6. The method for preparing a two-dimensional perovskite structure oxide / carbon composite absorbing material according to claim 1, characterized in that: The calcination parameters of S5 are: 5-10°C·min under inert atmosphere. -1 The temperature is raised to 550-600°C at a heating rate and calcined for 2-2.5 hours.

7. A two-dimensional perovskite structure oxide / carbon composite absorbing material, characterized in that: The material is prepared according to the method for preparing a two-dimensional perovskite structure oxide / carbon composite absorbing material as claimed in any one of claims 1 to 6.

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