W-type barium ferrite doped with rare earth cerium element and nickel element and its preparation method

Abstract

The present invention relates to a W-type barium ferrite doped with rare earth cerium element and nickel element and a preparation method thereof. The preparation method comprises the following steps: dissolving an iron salt, a barium salt, a nickel salt, a cerium salt and citric acid in water to obtain a precursor solution; then subjecting the solution to an oil bath to obtain a gel; and then calcining the dried gel at a high temperature to obtain a W-type barium ferrite doped with rare earth cerium element and nickel element. The W-type barium ferrite doped with rare earth cerium element and nickel element of the present invention has good impedance matching and strong loss ability, and has good wave absorption performance at a relatively thin thickness.

Description

Technical Field

[0001] The present invention belongs to the technical field of electromagnetic wave absorbing materials, and particularly relates to a W-type barium ferrite doped with rare earth cerium element and nickel element and a preparation method thereof. Background Art

[0002] The information disclosed in the background art of the present invention is only intended to increase the understanding of the overall background of the present invention, and is not necessarily regarded as an admission or an indication in any form that this information constitutes the prior art already known to those of ordinary skill in the art.

[0003] In recent years, with the rapid progress of science and technology and the continuous development of electronic information technology, people have entered an environment full of electromagnetic radiation. The bad electromagnetic environment not only causes interference and harm to people's daily communication and various electronic systems, but also poses a certain threat to people's physical health. The problem of electromagnetic radiation has gradually attracted people's attention. Among them, electromagnetic wave absorbing materials have become an important means to achieve electromagnetic protection due to their wide application range. W-type ferrite is a traditional electromagnetic wave absorbing material with excellent performance but a relatively large density.

[0004] Doping ferrite with rare earth elements can increase the loss intensity of the ferrite wave-absorbing material and broaden the effective absorption bandwidth. The reasons are as follows: on the one hand, rare earth elements will enhance the magnetocrystalline anisotropy field of the crystal, greatly increasing the resistance of domain wall displacement, which is conducive to the improvement of the magnetic hysteresis loss of the material; on the second hand, the average grain size of the crystal will increase due to the doping of rare earth elements, the resistivity of the grain boundary becomes smaller, and the resistivity of the whole crystal also decreases accordingly, thereby increasing the eddy current loss of the material. At the same time, it can also improve the multiple scattering loss and resonance loss to a certain extent; on the third hand, rare earth elements can improve the activity of grain boundary domain walls, increase the domain wall loss and natural resonance, and the interaction between rare earth elements and other elements makes the material more conducive to broadening the effective absorption frequency band under the action of natural resonance, domain wall resonance and exchange resonance; on the fourth hand, in the crystal, the rich rare earth energy levels are conducive to increasing the density of crystal energy levels, making it easier to occur energy level transitions, so that the energy conversion process between rare earth ions and other ions increases, enhancing the attenuation ability of electromagnetic waves, and realizing multi-band absorption of electromagnetic waves by the material. Summary of the Invention

[0005] The purpose of the present invention is to provide a W-type barium ferrite doped with rare earth cerium element and nickel element and a preparation method thereof, in order to endow the material with strong loss and good impedance matching. Because nickel element has paramagnetic behavior, the presence of nickel element can change the anisotropy of ferrite, reduce the magnetic flux and the coercivity, making it have good impedance matching and good wave-absorbing performance at a relatively thin thickness.

[0006] In the first aspect of the present invention, a method for preparing W-type barium ferrite doped with rare earth cerium element and nickel element is provided, including the following steps: dissolving iron salt, barium salt, nickel salt, cerium salt and citric acid in water to obtain a precursor solution; then performing an oil bath on the solution to obtain a gel; and then subjecting the dried gel to high-temperature calcination to obtain W-type barium ferrite doped with rare earth cerium element and nickel element.

[0007] For the W-type barium ferrite doped with rare earth cerium element prepared by the present invention, on the one hand, the rare earth element will enhance the magnetocrystalline anisotropy field of the crystal, greatly increasing the resistance to domain wall displacement, which is beneficial to the improvement of the magnetic hysteresis loss of the material; on the second hand, the average grain size of the crystal will increase due to the doping of the rare earth element, the resistivity of the grain boundary becomes smaller, and the resistivity of the whole crystal also decreases accordingly, thereby increasing the eddy current loss of the material. At the same time, the multiple scattering loss and resonance loss can also be increased to a certain extent; on the third hand, the rare earth element can improve the activity of the grain boundary domain wall, increase the domain wall loss and natural resonance, and the interaction between the rare earth element and other elements makes the material more conducive to broadening the effective absorption frequency band under the action of natural resonance, domain wall resonance and exchange resonance; on the fourth hand, in the crystal, the rich rare earth energy levels are beneficial to increasing the density of the crystal energy levels, making it easier to occur energy level transitions, so that the energy conversion process between rare earth ions and other ions increases, and the attenuation ability of electromagnetic waves is enhanced, and the multi-band absorption of electromagnetic waves by the material can be realized.

[0008] In the second aspect of the present invention, a W-type barium ferrite doped with rare earth cerium element and nickel element prepared by the above method.

[0009] In the third aspect of the present invention, a composite absorbing material is obtained by mixing W-type barium ferrite doped with rare earth cerium element and nickel element with paraffin.

[0010] In the fourth aspect of the present disclosure, the application of the above W-type barium ferrite doped with rare earth cerium element and nickel element or the composite absorbing material in the field of electromagnetic wave absorption.

[0011] The beneficial effects of the present invention are as follows:

[0012] (1) On the one hand, rare earth elements can enhance the magnetocrystalline anisotropy field of the crystal, greatly increasing the resistance to domain wall displacement, which is conducive to improving the magnetic hysteresis loss of the material; on the second hand, the average grain size of the crystal will increase due to the doping of rare earth elements, the resistivity of the grain boundary will decrease, and the resistivity of the whole crystal will also decrease accordingly, thus increasing the eddy current loss of the material. At the same time, the multiple scattering loss and resonance loss can also be increased to a certain extent; on the third hand, rare earth elements can improve the activity of grain boundary domain walls, increase the domain wall loss and natural resonance, and interact with other elements, making the material more conducive to broadening the effective absorption band under the action of natural resonance, domain wall resonance and exchange resonance; on the fourth hand, in the crystal, the rich rare earth energy levels are conducive to increasing the density of crystal energy levels, making it easier to have energy level transitions, thus increasing the energy conversion processes between rare earth ions and other ions, enhancing the attenuation ability of electromagnetic waves, and enabling the material to achieve multi-band absorption of electromagnetic waves.

[0013] (2) The added nickel element can reduce the magnetic flux of the ferrite and decrease the coercive force.

[0014] (3) The material prepared by the present invention has good wave absorption effect, and therefore is expected to be widely used in the preparation of electromagnetic wave absorbing materials.

[0015] (4) The W-type barium ferrite doped with rare earth cerium element (Ba 1-x Ce x Ni 2 Fe 15.4 O 27 ) and paraffin are compounded to obtain a wave absorbing material. When the doping amount x = 0.2, the absorption intensity is -42.799 dB, and the effective absorption bandwidth is 1.225 GHz; compared with the undoped W-type barium ferrite, the wave absorbing material of the W-type barium ferrite doped with rare earth cerium element has higher wave absorption performance and has wide application value. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] The specification drawings forming a part of the present invention are used to provide a further understanding of the present invention. The schematic embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention.

[0017] Figure 1 FIG. is the reflection loss diagram of the W-type barium ferrite doped with cerium element (Ba 0.8 Ce 0.2 Ni 2 Fe 15.4 O 27 ) for Example 1.

[0018] Figure 2 FIG. is the W-type barium ferrite doped with cerium element (Ba 0.9 Ce0.1 Ni 2 Fe 15.4 O 27 ) SEM image.

[0019] Figure 3 For the W-type barium ferrite (Ba 0.75 Ce 0.25 Ni 2 Fe 15.4 O 27 ) reflection loss graph.

[0020] Figure 4 For the W-type barium ferrite (Ba 0.85 Ce 0.15 Ni 2 Fe 15.4 O 27 ) SEM image.

[0021] Figure 5 For the XRD graph of the W-type barium ferrite (BaNi 2 Fe 15.4 O 27 ) prepared in the comparative example.

[0022] Figure 6 For the reflection loss graph of the undoped W-type barium ferrite (BaNi 2 Fe 15.4 O 27 ) prepared in the comparative example. Detailed implementation manners

[0023] It should be noted that the following detailed description is exemplary and is intended to provide further illustration of the present invention. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by those of ordinary skill in the technical field to which the present invention belongs.

[0024] Currently, for undoped W-type ferrite microwave absorbing materials, their loss mechanisms are single, and it is difficult to achieve both strong loss and impedance matching simultaneously. Therefore, by reasonably designing the composition of the material to form a multi-component composite material and utilizing the synergistic effect to improve the electromagnetic parameters of the material, the present invention provides a W-type barium ferrite doped with rare earth cerium element, its preparation method and application.

[0025] In one embodiment of the present invention, a preparation method of a W-type barium ferrite doped with rare earth cerium element and nickel element includes dissolving iron salt, barium salt, nickel salt, cerium salt and citric acid in water to obtain a precursor solution; then performing an oil bath on the solution to obtain a gel; and then performing high-temperature calcination on the dried gel to obtain a W-type barium ferrite doped with rare earth cerium element and nickel element.

[0026] In some embodiments of the present invention, the iron salt is selected from one or more of iron nitrate, iron sulfate, and iron chloride.

[0027] In some embodiments of the present invention, the barium salt is selected from one or two of barium nitrate and barium chloride.

[0028] In some embodiments of the present invention, the nickel salt is selected from one or more of nickel nitrate, nickel sulfate, and nickel chloride.

[0029] In some embodiments of the present invention, the cerium salt is selected from cerium nitrate.

[0030] In some embodiments of the present invention, the molar ratio of the addition of iron salt, barium salt, nickel salt, cerium salt, and citric acid is 15.4:1 - x:2:x:18.4, where x is 0 - 0.25; further, x = (0.00, 0.01, 0.10, 0.15, 0.20, 0.25).

[0031] In some embodiments of the present invention, the reaction temperature of the oil bath is (50 - 100) °C, and the reaction time is (10 - 15) h; citric acid plays a complexing role, and the above addition ratio, temperature, and time contribute to the formation of a gel doped with cerium elements.

[0032] In some embodiments of the present invention, the calcination temperature of the gel doped with cerium elements is (1000 - 1400) °C, the heating rate is (3 - 5) °C / min, and the reaction time is 3 h.

[0033] In one embodiment of the present invention, for the W-type barium ferrite obtained by the method for preparing a W-type barium ferrite doped with rare earth cerium and nickel elements, the ferrite contains Fe, Ba, Ce, Ni, and O elements.

[0034] In one embodiment of the present invention, a composite absorbing material, characterized in that the composite absorbing material comprises the W-type barium ferrite doped with rare earth cerium and nickel elements and paraffin wax. Further, the mass ratio of the W-type barium ferrite doped with rare earth cerium and nickel elements to paraffin wax is 0.144 g:0.056 g.

[0035] The paraffin wax is solid paraffin wax. The solid paraffin wax and the W-type barium ferrite powder are mixed by stirring or other means, rather than the paraffin wax being on the surface of the W-type barium ferrite material doped with cerium elements.

[0036] In one embodiment of the present invention, the method for preparing the composite absorbing material comprises the following steps: mixing the W-type barium ferrite doped with rare earth cerium and nickel elements and paraffin wax to obtain the composite absorbing material;

[0037] Furthermore, the temperature for mixing the W-type barium ferrite doped with rare earth cerium element and nickel element with paraffin is 30-60 °C.

[0038] After the W-type barium ferrite doped with rare earth cerium element and nickel element and paraffin are uniformly mixed, the barium ferrite and paraffin form a basically uniform distribution in the microwave absorbing material. The effect of mixing at a certain high temperature is to enhance the fluidity of paraffin, which helps the paraffin to be uniformly mixed with the W-type barium ferrite doped with cerium element.

[0039] In an embodiment of the present invention, the application of the W-type barium ferrite and / or the composite microwave absorbing material in the field of electromagnetic wave absorption.

[0040] The following combines specific embodiments to further elaborate on the present invention. It should be noted that the specific embodiments are explanations rather than limitations of the present invention.

[0041] Example 1

[0042] (1) Dissolve 0.9515 g of barium salt, 1.6630 g of nickel salt, 28.3156 g of iron salt, 0.3952 g of cerium salt, and 13.2688 g of citric acid in 30 mL of water. After stirring for 20 min, transfer it to an oil bath at 80 °C and react for 12 h. After the reaction is completed, put the obtained gel into an oven and dry it at 90 °C.

[0043] (2) Put the dry gel obtained in (1) into a crucible and place it in a tube furnace. Heat it to 1280 °C at a rate of 5 °C / min and calcine for 3 h. First, cool it to 400 °C at a rate of 5 °C / min, and then naturally cool it to room temperature to obtain black powder. Mix the black powder and paraffin according to a filling amount of 80% and press them into a ring structure.

[0044] Figure 1 The reflection loss diagram of the W-type barium ferrite doped with rare earth cerium element and nickel element prepared for Example 1, the loss intensity can reach 42.799 dB, and the effective absorption bandwidth can reach 1.225 GHz.

[0045] Example 2

[0046] (1) Dissolve 0.9515 g of barium salt, 1.4782 g of nickel salt, 25.1694 g of iron salt, 0.1757 g of cerium salt, and 13.2688 g of citric acid in 30 mL of water. After stirring for 20 min, transfer it to an oil bath at 80 °C and react for 12 h. After the reaction is completed, put the obtained gel into an oven and dry it at 90 °C.

[0047] (2) Put the xerogel obtained in (1) into a crucible and place it in a tube furnace. Heat it to 1280 °C at a rate of 5 °C / min and calcine for 3 h. First, cool it to 400 °C at a rate of 5 °C / min, and then let it cool naturally to room temperature to obtain black powder.

[0048] Figure 2 SEM image of the W-type barium ferrite doped with rare earth cerium and nickel elements prepared in Example 2, which determines that the prepared ferrite is a hexagonal flake structure.

[0049] Example 3

[0050] (1) Dissolve 0.9515 g of barium salt, 1.7739 g of nickel salt, 30.2033 g of iron salt, 0.5270 g of cerium salt, and 13.2688 g of citric acid in 30 mL of water. After stirring for 20 min, transfer it to an oil bath at 80 °C and react for 12 h. After the reaction is completed, put the obtained gel into an oven and dry it at 90 °C.

[0051] (2) Put the xerogel obtained in (1) into a crucible and place it in a tube furnace. Heat it to 1280 °C at a rate of 5 °C / min and calcine for 3 h. First, cool it to 400 °C at a rate of 5 °C / min, and then let it cool naturally to room temperature to obtain black powder. Mix the black powder and paraffin according to a filling amount of 80% and press them into a ring structure.

[0052] Figure 3 Reflection loss diagram of the W-type barium ferrite doped with rare earth cerium and nickel elements prepared in Example 3. The loss intensity can reach 36.4007 dB, and the effective absorption bandwidth can reach 0.875 GHz.

[0053] Example 4

[0054] (1) Dissolve 0.9515 g of barium salt, 1.4004 g of nickel salt, 23.8447 g of iron salt, 0.0832 g of cerium salt, and 13.2688 g of citric acid in 30 mL of water. After stirring for 20 min, transfer it to an oil bath at 80 °C and react for 12 h. After the reaction is completed, put the obtained gel into an oven and dry it at 90 °C.

[0055] (2) Put the xerogel obtained in (1) into a crucible and place it in a tube furnace. Heat it to 1280 °C at a rate of 5 °C / min and calcine for 3 h. First, cool it to 400 °C at a rate of 5 °C / min, and then let it cool naturally to room temperature to obtain black powder.

[0056] Example 5

[0057] (1) Dissolve 0.9515 g of barium salt, 1.5652 g of nickel salt, 26.6500 g of iron salt, 0.2790 g of cerium salt, and 13.2688 g of citric acid in 30 mL of water. After stirring for 20 min, transfer it to an oil bath and react at 80 °C for 12 h. After the reaction is completed, put the obtained gel into an oven and dry it at 90 °C.

[0058] (2) Put the dry gel obtained in (1) into a crucible and place it in a tube furnace. Heat it to 1280 °C at a rate of 5 °C / min and calcine for 3 h. First, cool it to 400 °C at a rate of 5 °C / min, and then cool it naturally to room temperature to obtain black powder.

[0059] Figure 4 It is the SEM image of the W-type barium ferrite doped with rare earth cerium element and nickel element prepared in Example 5, and the crystallinity of the prepared ferrite is good.

[0060] Comparative Example

[0061] (1) Dissolve 0.9515 g of barium salt, 1.3304 g of nickel salt, 22.6525 g of iron salt, and 13.2688 g of citric acid in 30 mL of water. After stirring for 20 min, transfer it to an oil bath and react at 80 °C for 12 h. After the reaction is completed, put the obtained gel into an oven and dry it at 90 °C.

[0062] (2) Put the dry gel obtained in (1) into a crucible and place it in a tube furnace. Heat it to 1280 °C at a rate of 5 °C / min and calcine for 3 h. First, cool it to 400 °C at a rate of 5 °C / min, and then cool it naturally to room temperature to obtain black powder. Mix the black powder and paraffin according to a filling amount of 80% and press them into a ring structure.

[0063] Figure 5 It is the XRD pattern of the prepared W-type barium ferrite, and it is determined that the prepared is W-type barium ferrite.

[0064] Figure 6 It is the reflection loss diagram of the prepared undoped W-type barium ferrite. It can be seen that the reflection loss is not as good as that in Example 1, and the wave absorption performance is poor.

[0065] The above are only the preferred embodiments of the present invention and are not used to limit the present invention. For those skilled in the art, the present invention can have various modifications and changes. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A composite wave-absorbing material, characterized in that, the composite wave-absorbing material comprises W-type barium ferrite doped with rare earth cerium element and nickel element and paraffin; the mass ratio of the W-type barium ferrite doped with rare earth cerium element and nickel element to paraffin is 0.144 g: 0.056 g; the preparation method of the W-type barium ferrite doped with rare earth cerium element and nickel element comprises the following steps: dissolving iron salt, barium salt, nickel salt, cerium salt and citric acid in water to obtain a precursor solution; then carrying out an oil bath on the precursor solution to obtain a gel; then calcining the dried gel at a high temperature, raising the temperature to 1280 °C at 5 °C / min and calcining for 3 h, first cooling to 400 °C at 5 °C / min, and then naturally cooling to room temperature to obtain the W-type barium ferrite doped with rare earth cerium element and nickel element; the molar ratio of the iron salt, barium salt, nickel salt, cerium salt and citric acid is 15.4: 1 - x: 2: x: 18.4, where x is 0.01, 0.10, 0.15, 0.20 or 0.25; the reaction temperature of the oil bath is 80 °C and the reaction time is 12 h.

2. The composite wave-absorbing material according to claim 1, characterized in that, its preparation method comprises the following steps: mixing the W-type barium ferrite doped with rare earth cerium element and nickel element and paraffin to obtain a composite wave-absorbing material; the mixing temperature of the W-type barium ferrite doped with rare earth cerium element and nickel element and paraffin is 30 - 60 °C.

3. The composite wave-absorbing material according to claim 1, characterized in that, the iron salt is selected from one or more of iron nitrate, iron sulfate, and iron chloride; the barium salt is selected from one or two of barium nitrate and barium chloride; the nickel salt is selected from one or more of nickel nitrate, nickel sulfate, and nickel chloride; the cerium salt is selected from cerium nitrate.

4. The application of the composite wave-absorbing material according to any one of claims 1 - 3 in the field of electromagnetic wave absorption.

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