Preparation method and application of SrFe12O19 / Ag3PO4 nano composite material

Abstract

The invention discloses a preparation method and application of a SrFe12O19 / Ag3PO4 nano composite material, and the preparation method comprises the following steps: 1) respectively weighing 0.50 g of SrFe12O19 powder and 0.20 g-0. 33g of AgNO3 powder, dissolving the SrFe12O19 powder and the AgNO3 powder in 50 mL of deionized water, uniformly mixing the SrFe12O19 powder and the AgNO3 powder, and then mechanically stirring the SrFe12O19 powder and the AgNO3 powder for 20-30 minutes; (2) adding 100mL of a Na2HPO4 solution with the concentration of 0.75 mol / mL drop by drop until the solution is completely precipitated; and 3) after the reaction is finished, alternately washing the product with deionized water and ethanol, then centrifugally separating with a centrifugal machine, and alternately carrying out the process for three times. And 4) washing with ethanol, then centrifugally separating with a centrifugal machine, and drying in a drying oven at 60 DEG C to obtain the SrFe12O19 / Ag3PO4 nano composite material. The composite material combines high dielectric loss of Ag3PO4 and high magnetic loss of SrFe12O19, realizes organic combination of dielectric loss and magnetic loss, and has light weight, broadband and efficient wave absorbing performance.

Description

Technical Field

[0001] The present invention relates to the technical field of preparation and application of absorbing materials, and specifically to a preparation method of a broadband, lightweight, and highly efficient absorbing material and a study of its performance, especially for SrFe 12 O 19 Preparation of / Ag3PO4 nanocomposites. Background Art

[0002] Since its breakthrough, electromagnetic technology has been widely used in many fields, such as 5G technology in the communication field, photovoltaic power generation and wind power generation in the new energy field, magnetic levitation trains in the transportation field, and magnetic resonance imaging in the medical field. Electromagnetic technology has not only had a profound impact on the fields of communication, energy, transportation, etc., but also promoted the process of industrialization and global development, greatly improving people's quality of life. However, with the popularity and increasing complexity of electromagnetic products, electromagnetic radiation and electromagnetic interference problems are becoming increasingly serious. The application of absorbing materials on electronic facilities can absorb or convert electromagnetic waves projected onto the surface, thereby weakening the reflected wave energy and reducing the harm of environmental electromagnetic pollution to the human body. Therefore, the research and development of absorbing materials is of great significance.

[0003] Ferrite is a ferromagnetic metal oxide composed of iron and other metal oxides. Its electromagnetic wave absorption mechanism is mainly polarization effect and natural resonance, among which natural resonance is its most important absorption mechanism. The magnetism of ferrite mainly comes from the electron spin magnetic moment. Under the action of an external magnetic field, forced precession is achieved when the alternating magnetic field frequency is equal to the precession frequency. The energy provided by the high-frequency alternating magnetic field finally achieves resonance absorption. At the same time, because of its low price, high saturation magnetization intensity, good low-frequency microwave absorption performance, high resistivity, it can effectively avoid the skin effect of metal conductors at high frequencies, and can be combined with other absorbing materials to adjust coating parameters. It has become one of the more popular absorbing materials in current research. However, a single ferrite absorbing material has the disadvantages of high density and narrow absorption bandwidth, which limits its wider application in the field of microwave absorption. Therefore, combining a single ferrite absorbing material with other absorbing materials has become a current research hotspot. Summary of the invention

[0004] The present invention aims to overcome the shortcomings of the prior art and provide a SrFe 12 O 19 / Ag3PO4 nanocomposite material and preparation method thereof. The composite material combines the high dielectric loss of Ag3PO4 and the 12 O 19 The high magnetic loss achieves the organic combination of dielectric and magnetic loss, and at the same time has light weight, broadband and high-efficiency wave absorbing performance.

[0005] The technical solution of the present invention is as follows:

[0006] A SrFe 12 O 19 The preparation method of the Ag3PO4 nanocomposite material comprises the following steps:

[0007] (1) Weigh SrFe 12 O 19 powder and AgNO3 powder, dissolved in deionized water, mixed evenly and stirred for 20 to 30 minutes, mixed evenly and mechanically stirred, wherein SrFe 12 O 19 The mass ratio of SrFe powder to AgNO3 powder is 5:2~3.3. 12 O 19 The mass ratio of powder to deionized water is 1-5:100-500

[0008] (2) Add a 0.75 mol / mL Na2HPO4 solution dropwise until complete precipitation, with the volume ratio of Na2HPO4 solution to deionized water being 2 to 3:1;

[0009] (3) After the reaction is completed, the product is washed alternately with deionized water and ethanol, and then centrifuged using a centrifuge. The washing and centrifugation process is alternately performed three times;

[0010] (4) Wash the product with ethanol, centrifuge it again, and finally dry it in an oven to obtain SrFe 12 O 19 / Ag3PO4 nanocomposite materials.

[0011] Preferably, the oven in the above step (4) is an oven at 60° C., and the drying time is 24 hours.

[0012] Preferably, the SrFe 12 O 19 The specific preparation method of the powder is:

[0013] a) Weigh Sr(NO3)2 and Fe(NO3)3·9H2O respectively, add them into 30 mL of distilled water and stir magnetically for 30 minutes until they are evenly mixed; the mass ratio of Sr(NO3)2 to Fe(NO3)3·9H2O is 0.4232:3.2309, and the mass ratio of Sr(NO3)2 to distilled water is 0.4232:30;

[0014] b) weighing NaOH and adding it to distilled water, and shaking it evenly in an ultrasonic cleaner; wherein the mass ratio of Sr(NO3)2 to NaOH is 0.4232:3.3591, and the volume ratio of distilled water in step a) to that in step b) is 3:2;

[0015] c) slowly dripping the uniformly shaken NaOH solution into the mixed solution drop by drop until a layer of floccules is observed in the mixed solution;

[0016] d) After the NaOH solution is dripped, stirring is continued until the reaction is complete, and the resulting solution is transferred into a polytetrafluoroethylene hydrothermal reactor and reacted at 220° C. for 5 hours;

[0017] e) Wash the product, centrifuge it, and dry it at 80°C for later use, including 4 acid washes, 4 water washes, and 1 alcohol wash, with a drying time of 12 to 24 hours.

[0018] The present invention also provides a SrFe 12 O 19 Application of / Ag3PO4 nanocomposites as absorbers in microwave absorbing materials.

[0019] The beneficial effects of the present invention are:

[0020] 1. The hydrothermal method and ion exchange method adopted in the present invention have the advantages of simple process, easy operation and low energy consumption.

[0021] 2. The present invention can achieve dielectric and magnetic loss (Ag3PO4 is a high dielectric loss material, SrFe 12 O 19 Ag3PO4 is a semiconductor material, which can achieve the purpose of lightweight materials.

[0022] 3. The ferrite-based composite absorber used in the present invention has the advantages of wide bandwidth, light weight and high efficiency compared with single ferrite.

[0023] 4. The present invention provides a new modification method with simple process and low cost, which is suitable for preparing composite absorbing materials with excellent absorbing performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 The SrFe prepared in Example 1 of the present invention 12 O 19 / Ag3PO4 composite material sample SEM image.

[0025] Figure 2 SrFe prepared in Examples 1 to 3 12 O 19 / Ag3PO4 nanocomposite material sample.

[0026] Figure 3 SrFe was prepared for different mass ratios 12 O 19Distribution curve of reflection loss (RL) and frequency (f) of Ag3PO4-paraffin mixed sample in the frequency range of 2 to 18 GHz and given absorbing coating thickness (1.0 to 5.5 mm).

[0027] Where: a, b, c, d are SrFe 12 O 19 - Paraffin mixed sample and preparation of SrFe in Examples 1 to 3 12 O 19 / Ag3PO4-paraffin mixed sample. DETAILED DESCRIPTION

[0028] The present invention will be further described below in conjunction with the accompanying drawings. The following embodiments are only used to more clearly illustrate the technical solution of the present invention, and cannot be used to limit the protection scope of the present invention.

[0029] Example 1

[0030] First, install a 200 mL beaker on a magnetic stirrer, then add 50 mL of deionized water, 0.50 g of SrFe 12 O 19 The powder and 0.20g AgNO3 were mixed evenly and magnetically stirred for 30 minutes. Then 100mL 0.75mol / mL Na2HPO4 solution was added dropwise until complete precipitation. After the reaction was completed, the product was washed with deionized water and centrifuged three times, then washed with ethanol and centrifuged, and dried in a 60℃ oven to obtain SrFe with an Ag3PO4 attachment of 3%. 12 O 19 / Ag3PO4 nanocomposite materials.

[0031] The prepared nanocomposite material was mixed with paraffin (mass fraction of the sample was 40%) and pressed into a ring with an outer diameter of 7.00 mm, an inner diameter of 3.04 mm and a thickness of 2 mm. Its electromagnetic parameters were tested using a vector network analyzer, and the reflection loss of the sample was calculated based on the electromagnetic parameters.

[0032] Example 2

[0033] First, install a 200 mL beaker on a magnetic stirrer, then add 50 mL of deionized water, 0.50 g of SrFe 12 O 19 The powder and 0.27g AgNO3 were mixed evenly and stirred magnetically for 30 minutes. Then 100mL 0.75mol / mL Na2HPO4 solution was added dropwise until complete precipitation. After the reaction was completed, the product was washed with deionized water and centrifuged three times, then washed with ethanol and centrifuged, and dried in a 60℃ oven to obtain SrFe with an Ag3PO4 attachment of 4%. 12 O19 / Ag3PO4 nanocomposite materials.

[0034] The prepared nanocomposite material was mixed with paraffin (mass fraction of the sample was 40%) and pressed into a ring with an outer diameter of 7.00 mm, an inner diameter of 3.04 mm and a thickness of 2 mm. Its electromagnetic parameters were tested using a vector network analyzer, and the reflection loss of the sample was calculated based on the electromagnetic parameters.

[0035] Example 3

[0036] First, install a 200 mL beaker on a magnetic stirrer, then add 50 mL of deionized water, 0.50 g of SrFe 12 O 19 The powder and 0.33g AgNO3 were mixed evenly and magnetically stirred for 30 minutes. Then 100mL 0.75mol / mL Na2HPO4 solution was added dropwise until complete precipitation. After the reaction was completed, the product was washed with deionized water and centrifuged three times, then washed with ethanol and centrifuged, and dried in a 60℃ oven to obtain SrFe with an Ag3PO4 attachment amount of 5%. 12 O 19 / Ag3PO4 nanocomposite materials.

[0037] The nanocomposite powder prepared above was mixed with paraffin (the mass fraction of the sample was 40%) and pressed into a ring with an outer diameter of 7.00 mm, an inner diameter of 3.04 mm, and a thickness of 2 mm. Its electromagnetic parameters were tested using a vector network analyzer, and the reflection loss of the sample was calculated based on the electromagnetic parameters.

[0038] Attached Figure 3 SrFe was prepared for different mass ratios 12 O 19 The distribution curve of reflection loss (RL) and frequency (f) of the mixed sample of / Ag3PO4-paraffin in the frequency range of 2 to 18 GHz and a given absorbing coating thickness (1.0 to 5.5 mm). A, B, C, and D are SrFe 12 O 19 , SrFe with Ag3PO4 attachment of 3%, 4%, and 5% 12 O 19Wave absorbing performance of the mixed sample of / Ag3PO4 composite material powder and paraffin. As can be seen from the figure, when the thickness of the wave absorbing coating of sample A is 5.0mm, the minimum reflection loss is only -10.1dB, the effective absorption frequency band below -5dB is 5.4-7.5GHz, and the effective absorption bandwidth is 2.1GHz. When the thickness of the wave absorbing coating of sample B is 5.0mm, the minimum reflection loss reaches -23.6dB, the effective absorption frequency band below -5dB is 3.9~7.9GHz, and the effective absorption bandwidth is 4.0GHz. When the thickness of the wave absorbing coating of sample C is 5.0mm, the minimum reflection loss reaches -16.1dB, the effective absorption frequency band below -5dB is 5.4-7.8GHz, and the effective absorption bandwidth is 2.4GHz. When the thickness of the absorbing coating of sample D is 5.0mm, the minimum reflection loss at 7.3GHz is -12.4dB, the effective absorption frequency band below -5dB is 5.4-7.9GHz, and the effective absorption bandwidth is 2.5GHz. Compared with the absorption performance of sample A, samples B, C, and D not only have improved absorption performance, but also have wider bandwidth.

[0039] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the technical principles of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A SrFe 12 O 19 A method for preparing a / Ag3PO4 nanocomposite material, characterized in that: The following steps are involved: (1) Weigh SrFe 12 O 19 powder and AgNO3 powder, dissolved in deionized water, mixed evenly and stirred for 20 to 30 minutes, and mechanically stirred after mixing evenly. 12 O 19 The mass ratio of SrFe powder to AgNO3 powder is 5:2~3.

3. 12 O 19 The mass ratio of powder to deionized water is 1-5:100-500; (2) Add 0.75 mol / mL Na2HPO4 solution dropwise until complete precipitation, with the volume ratio of Na2HPO4 solution to deionized water being 2-3:1; (3) After the reaction is completed, the product is washed alternately with deionized water and ethanol, and then centrifuged using a centrifuge. The washing and centrifugation process is alternately performed three times; (4) Wash the product with deionized water and ethanol, centrifuge it, and finally dry it in an oven to obtain SrFe 12 O 19 / Ag3PO4 nanocomposite materials.

2. A SrFe according to claim 1 12 O 19 A method for preparing a / Ag3PO4 nanocomposite material, characterized in that: The oven in step (4) is a 60° C. oven, and the drying time is 24 hours.

3. A SrFe according to claim 1 12 O 19 A method for preparing a / Ag3PO4 nanocomposite material, characterized in that: The SrFe 12 O 19 The specific preparation method of the powder is: a) Weigh Sr(NO3)2 and Fe(NO3)3·9H2O respectively, add them into 30 mL of distilled water and stir magnetically for 30 minutes until they are evenly mixed; the mass ratio of Sr(NO3)2 to Fe(NO3)3·9H2O is 0.4232:3.2309, and the mass ratio of Sr(NO3)2 to distilled water is 0.4232:30; b) weighing NaOH and adding it to distilled water, and shaking it evenly in an ultrasonic cleaner; wherein the mass ratio of Sr(NO3)2 to NaOH is 0.4232:3.3591, and the volume ratio of distilled water in step a) to that in step b) is 3:2; c) slowly dripping the uniformly shaken NaOH solution into the mixed solution drop by drop until a layer of floccules is observed in the mixed solution; d) After the NaOH solution is dripped, stirring is continued until the reaction is complete, and the resulting solution is transferred into a polytetrafluoroethylene hydrothermal reactor and reacted at 220° C. for 5 hours; e) Wash the product, centrifuge it, and dry it at 80°C for later use, including 4 acid washes, 4 water washes, and 1 alcohol wash, with a drying time of 12 to 24 hours.

4. A SrFe prepared by the method according to any one of claims 1 to 3 12 O 19 Application of / Ag3PO4 nanocomposites as absorbers in microwave absorbing materials.

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