Rare earth neodymium and pentavalent ion double substitution M-type barium ferrite dual-band wave absorber and preparation method thereof

Abstract

The application discloses a rare earth neodymium and pentavalent ion double-site substituted M-type barium ferrite double-band wave absorber and a preparation method thereof. 1‑x Nd x Fe 12‑y A y O 19 , wherein A is a pentavalent transition metal ion Nb or Ta, x=0.05-0.3, and y=0.05-0.3. The application realizes double-site substitution of the M-type barium ferrite by using the rare earth element Nd 3+ and the non-magnetic ion A (Nb 5+ , Ta 5+ ) to respectively replace part of Ba 2+ ions and part of Fe 3+ ions of the M-type barium ferrite, so that the obtained wave absorbing material has the characteristics of strong reflection loss, wide effective absorption bandwidth and thin matching thickness.

Description

Technical Field

[0001] This invention relates to the field of microwave absorbing materials technology, specifically to a rare earth neodymium / pentavalent ion double-substituted M-type barium ferrite dual-band microwave absorbing agent and its preparation method. Background Technology

[0002] The Internet of Things (IoT) is one of the fastest-growing technologies in the modern world. To meet the development needs of IoT, the development and utilization of 5G technology is an urgent communication technology to be developed. The goal of 5G technology is to achieve higher data rates (>1Gb / s), machine-to-machine communication between different devices, minimal human intervention, high bandwidth, and low latency. In 5G NR, two frequency bands are defined: FR1 (410-7125MHz) and FR2 (24250-52600MHz) are defined. However, high-frequency electromagnetic waves cause more severe interference to electronic devices and also pose serious risks to the environment and human health. Furthermore, in the field of military stealth, radar remains a crucial means of capturing target information in modern warfare. Therefore, it is essential to minimize or eliminate reflected electromagnetic wave energy to avoid radar detection. Thus, whether for eliminating electromagnetic interference and protecting against electromagnetic radiation in civilian applications or improving the survivability of weapon systems in the military field, it is necessary to develop appropriate absorbing materials to absorb and attenuate unfavorable electromagnetic waves.

[0003] M-type barium ferrite has become a high-performance permanent magnet material due to its high uniaxial magnetocrystalline anisotropy, high coercivity, low cost, and high stability. However, its single resonant frequency and narrow effective absorption bandwidth limit its applications. Introducing suitable heteroions into the M-type barium ferrite matrix can effectively change its anisotropic field, thereby altering the natural resonant frequency of the M-type barium ferrite and shifting the peak of strong absorption to the ideal frequency band. The introduced heteroions may also introduce multiple Landé factors into the matrix, enabling multi-band absorption of the M-type barium ferrite and broadening its absorption bandwidth. The introduced heteroions interact with the Ba in the M-type barium ferrite... 2+ ions or Fe 3+ The ionic radii of the ions are not all the same, which causes distortion of the M-type barium ferrite lattice, which can change the dielectric properties of the M-type barium ferrite and introduce some dielectric loss for electromagnetic wave absorption.

[0004] Currently, when modifying M-type barium ferrite microwave absorbing materials by ion substitution, most methods choose to substitute only Ba with a single metal ion or a combination of multiple ions. 2+ ions or Fe 3+ Ions. For substituted Ba 2+ Research in this area, including many substituted ions such as Pb 2+ Ce 3+ La 3+、Sr 2+ Bi 3+ Ba has been extensively studied, and the results show that Ba 2+ Substitution of Fe in M-type barium ferrites can optimize their magnetic properties, enabling them to exhibit better absorption performance within the desired electromagnetic wave band. Furthermore, replacing Fe in M-type barium ferrites with non-magnetic or weakly magnetic ions and their combinations... 3+ The study of ions, such as Sc 3+ Ti 4+ Co 2+ -Ti 4+ La 3+ -Ce 3+ Zr 4+ -Ni 2+ Other studies have demonstrated that reducing the anisotropic field of M-type barium ferrite and enhancing the multiple magnetic resonances in the system can lower its natural resonant frequency and broaden its effective absorption bandwidth. However, there are few reports on microwave absorbing materials with dual-site substitution of M-type barium ferrite.

[0005] Rare earth elements generally possess characteristics such as unfilled 4f orbitals, large ionic radii, and a large number of electrons. Therefore, rare earth element substitution can interact with Fe in M-type barium ferrite. 3+ Ions generate magnetic interactions, causing lattice distortion and reducing the energy difference in the material's energy levels, thereby altering the dielectric magnetoelectric properties of M-type barium ferrite. Secondly, substitution with higher-valence ions in M-type barium ferrite easily induces ion displacement polarization in the lattice, improving the material's dielectric properties. Therefore, using rare-earth ions such as Nd... 3+ nonmagnetic ion Nb 5+ (Ta 5+ Replacing M-type barium ferrite with this technology is expected to improve the permeable magnetic properties of M-type barium ferrite, thereby obtaining a microwave absorbing agent with excellent microwave absorption performance. Summary of the Invention

[0006] The purpose of this invention is to provide a dual-substitute M-type barium ferrite absorbing agent and its preparation method for the frequency band corresponding to the prevention of 5G electromagnetic pollution and millimeter-wave radar stealth.

[0007] To achieve its objectives, the present invention employs the following technical solution:

[0008] This invention first proposes a rare-earth neodymium and pentavalent ion-disubstituted M-type barium ferrite dual-band absorbing agent, wherein the disubstituted M-type barium ferrite dual-band absorbing agent is Ba 1-x Nd x Fe 12-y A y O 19 Where A is at least one of pentavalent transition metal ions Nb and Ta ions, x = 0.05–0.3, y = 0.05–0.3.

[0009] This invention further proposes a method for preparing the rare earth neodymium and pentavalent ion dual-substituted M-type barium ferrite dual-band microwave absorber, characterized in that: rare earth element neodymium and pentavalent transition metal ion A(Nb) are used. 5+ Or Ta 5+ The Ba atoms that replace the M-type barium ferrite respectively 2+ Ions and some Fe 3+ The method involves simultaneously substituting two elements to obtain a rare-earth neodymium and pentavalent ion-substituted M-type barium ferrite dual-band microwave absorber. The method includes the following steps:

[0010] (1) Barium carbonate, neodymium oxide, iron oxide, oxide of A (at least one of niobium oxide and tantalum oxide) and boron oxide are mixed and ground in a preset ratio to obtain a premixed precursor;

[0011] (2) Place the premixed precursor obtained in step (1) into a zirconia ball mill jar, then add an appropriate amount of anhydrous ethanol for ball milling. After ball milling, dry to obtain ball milled powder.

[0012] (3) After grinding the ball mill powder obtained in step (2), it is calcined for the first time;

[0013] (4) After grinding the sample obtained in step (3), perform a second ball milling;

[0014] (5) The sample obtained in step (4) is calcined for the second time. After cooling to room temperature, the sample is thoroughly ground to finally obtain rare earth neodymium and pentavalent ion double-substituted M-type barium ferrite dual-band absorbing agent.

[0015] Further, in step (1), the molar ratio of barium carbonate, neodymium oxide, iron oxide, and niobium oxide (tantalum oxide) is preset according to the chemical formula of the product, and the amount of boron oxide added is 1 to 3% of the total mass of barium carbonate, neodymium oxide, iron oxide and oxide of A.

[0016] Furthermore, in step (2), the ball milling speed is 250-400 rpm, the ball milling time is 12-36 h, and the drying temperature is 60℃.

[0017] Furthermore, in step (3), the temperature of the first calcination is 1100-1400℃, the calcination time is 4-8h, and the heating rate is 10℃ / min.

[0018] Furthermore, in step (4), the second ball milling speed is 250-400 rpm, the ball milling time is 12-18 h, and the drying temperature is 60℃.

[0019] Furthermore, in step (5), the temperature of the second calcination is 1100-1400℃, the calcination time is 4-8h, and the heating rate is 10℃ / min.

[0020] The beneficial effects of this invention are reflected in:

[0021] 1. This invention introduces rare earth element neodymium ions and pentavalent transition metal element niobium (tantalum) ions into an M-type barium ferrite matrix via solid-state synthesis. The rare earth element Nd... 3+ Ba ion-substituted portion 2+ Ions, and Nb 5+ (Ta 5+ Fe ion-substituted portion 3+ The ion achieved the substitution of the di-site ion in the M-type barium ferrite. (Rare earth element Nd) 3+ Capable of reacting with Fe in M-type barium ferrite 3+ The magnetic interactions between ions cause lattice distortion, reducing the energy difference between material energy levels and thus altering the magnetoelectric properties of M-type barium ferrite. Simultaneously, the introduction of higher-valence ions, such as Nb, into the M-type barium ferrite... 5+ (Ta 5+ These elements readily induce ionic displacement polarization in the crystal lattice, thereby improving the dielectric properties of the material. Furthermore, increasing the proportion of high-valence substituted elements enhances the Fe... 3+ To Fe 2+ The transformation enhances Fe 3+ and Fe 2+ The exchange coupling between them. Nd 3+ Ions and Nb 5+ (Ta 5+ The simultaneous introduction of ions enables the material to exhibit electromagnetic wave absorption performance in both the 2–18 GHz and 26.5–40 GHz bands under the combined effect of natural resonance and exchange resonance.

[0022] 2. This invention adjusts the Nd content in M-type barium ferrite. 3+ Ions and Nb 5+ (Ta 5+ The substitution ratio of Nd ions can reduce the thickness of the absorbing agent and control the absorption frequency band of M-type barium ferrite, resulting in lighter and more effective absorbing materials. With the development of Nd... 3+ ions or Nb 5+ (Ta 5+ The introduction of Nd ions into M-type barium ferrite effectively improves the microwave absorption performance of the material. Substitution with high-valence ions can generate multiple magnetic resonances in the matrix, broadening its effective absorption bandwidth; by adjusting Nd... 3+ Ions and pentavalent metal Nb 5+ (Ta 5+The relative proportions of ions can achieve effective control of multiple magnetic resonances at a fixed frequency; pentavalent metal ions replacing Fe 3+ The ions effectively reduced the anisotropic field energy of the M-type barium ferrite, thereby gradually reducing the natural resonant frequency of the barium ferrite to within the 5G band range, and improving the matching thickness and effective bandwidth.

[0023] 3. The absorbing material of this invention features strong reflection loss, wide effective absorption bandwidth, and thin matching thickness. A sample with a certain amount of replacement exhibits good reflection loss in both frequency bands. For example, when the replacement amount x = y = 0.3, the optimal reflection loss value at a specific frequency can reach -47.08 dB (-34.84 dB). Furthermore, with a matching thickness of approximately 0.7 mm, effective electromagnetic wave absorption can fully cover the 26.5–40 GHz frequency band, i.e., an effective absorption bandwidth of 13.5 GHz.

[0024] 4. The preparation process of the microwave absorbing agent material in this invention is simple, the raw material cost is low, it is safe and pollution-free, the equipment is conventional, and it has the basic conditions required for large-scale production. At the same time, it provides a reference for the research of M-type barium ferrite microwave absorbing materials and magnetic materials. Attached Figure Description

[0025] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0026] Figure 1 This invention provides a neodymium-niobium dual-substituted M-type barium ferrite dual-band absorbing agent, Ba, obtained in Example 1 of this invention. 0.9 Nd 0.1 Fe 11.9 Nb 0.1 O 19 XRD patterns;

[0027] Figure 2 This invention provides a neodymium-niobium dual-substituted M-type barium ferrite dual-band absorbing agent, Ba, obtained in Example 1 of this invention. 0.9 Nd 0.1 Fe 11.9 Nb 0.1 O 19 XPS plot of Nb element;

[0028] Figure 3 This invention provides a neodymium-niobium dual-substituted M-type barium ferrite dual-band absorbing agent, Ba, obtained in Example 1 of this invention. 0.9 Nd 0.1 Fe 11.9 Nb0.1 O 19 Curves showing the relationship between absorption performance and frequency in the 2–18 GHz frequency range;

[0029] Figure 4 This invention provides a neodymium-niobium dual-substituted M-type barium ferrite dual-band absorbing agent, Ba, obtained in Example 1 of this invention. 0.9 Nd 0.1 Fe 11.9 Nb 0.1 O 19 The graph shows the relationship between absorption performance and frequency in the frequency range of 26.5 to 40 GHz.

[0030] Figure 5 This invention provides a neodymium-niobium dual-substituted M-type barium ferrite dual-band absorbing agent, Ba, obtained in Example 2 of this invention. 0.9 Nd 0.1 Fe 11.8 Nb 0.2 O 19 XRD patterns;

[0031] Figure 6 This invention provides a neodymium-niobium dual-substituted M-type barium ferrite dual-band absorbing agent, Ba, obtained in Example 2 of this invention. 0.9 Nd 0.1 Fe 11.8 Nb 0.2 O 19 Curves showing the relationship between absorption performance and frequency in the 2–18 GHz frequency range;

[0032] Figure 7 This invention provides a neodymium-niobium dual-substituted M-type barium ferrite dual-band absorbing agent, Ba, obtained in Example 2 of this invention. 0.9 Nd 0.1 Fe 11.8 Nb 0.2 O 19 The graph shows the relationship between absorption performance and frequency in the frequency range of 26.5 to 40 GHz.

[0033] Figure 8 This invention provides a neodymium-niobium dual-substituted M-type barium ferrite dual-band absorbing agent, Ba, obtained in Example 3 of this invention. 0.8 Nd 0.2 Fe 11.9 Nb 0.1 O 19 XRD patterns;

[0034] Figure 9 This invention provides a neodymium-niobium dual-substituted M-type barium ferrite dual-band absorbing agent, Ba, obtained in Example 3 of this invention. 0.8 Nd 0.2 Fe 11.9 Nb0.1 O 19 Curves showing the relationship between absorption performance and frequency in the 2–18 GHz frequency range;

[0035] Figure 10 This invention provides a neodymium-niobium dual-substituted M-type barium ferrite dual-band absorbing agent, Ba, obtained in Example 3 of this invention. 0.8 Nd 0.2 Fe 11.9 Nb 0.1 O 19 The graph shows the relationship between absorption performance and frequency in the frequency range of 26.5 to 40 GHz.

[0036] Figure 11 This invention provides a neodymium-niobium dual-substituted M-type barium ferrite dual-band absorber, Ba, obtained in Example 4 of this invention. 0.7 Nd 0.3 Fe 11.7 Nb 0.3 O 19 XRD patterns;

[0037] Figure 12 This invention provides a neodymium-niobium dual-substituted M-type barium ferrite dual-band absorber, Ba, obtained in Example 4 of this invention. 0.7 Nd 0.3 Fe 11.7 Nb 0.3 O 19 Curves showing the relationship between absorption performance and frequency in the 2–18 GHz frequency range;

[0038] Figure 13 This invention provides a neodymium-niobium dual-substituted M-type barium ferrite dual-band absorber, Ba, obtained in Example 4 of this invention. 0.7 Nd 0.3 Fe 11.7 Nb 0.3 O 19 The graph shows the relationship between absorption performance and frequency in the frequency range of 26.5 to 40 GHz.

[0039] Figure 14 This invention provides a neodymium-tantalum dual-substituted M-type barium ferrite dual-band absorbing agent, Ba, obtained in Example 5 of this invention. 0.9 Nd 0.1 Fe 11.9 Ta 0.1 O 19 XRD patterns;

[0040] Figure 15 This invention provides a neodymium-tantalum dual-substituted M-type barium ferrite dual-band absorbing agent, Ba, obtained in Example 5 of this invention. 0.9 Nd 0.1 Fe 11.9 Ta0.1 O 19 XPS plot of Nb element;

[0041] Figure 16 This invention provides a neodymium-tantalum dual-substituted M-type barium ferrite dual-band absorbing agent, Ba, obtained in Example 5 of this invention. 0.9 Nd 0.1 Fe 11.9 Ta 0.1 O 19 Curves showing the relationship between absorption performance and frequency in the 2–18 GHz frequency range;

[0042] Figure 17 This invention provides a neodymium-tantalum dual-substituted M-type barium ferrite dual-band absorbing agent, Ba, obtained in Example 5 of this invention. 0.9 Nd 0.1 Fe 11.9 Ta 0.1 O 19 The graph shows the relationship between absorption performance and frequency in the frequency range of 26.5 to 40 GHz.

[0043] Figure 18 This invention provides a neodymium-tantalum dual-substituted M-type barium ferrite dual-band absorbing agent, Ba, obtained in Example 6 of this invention. 0.9 Nd 0.1 Fe 11.8 Ta 0.2 O 19 XRD patterns;

[0044] Figure 19 This invention provides a neodymium-tantalum dual-substituted M-type barium ferrite dual-band absorbing agent, Ba, obtained in Example 6 of this invention. 0.9 Nd 0.1 Fe 11.8 Ta 0.2 O 19 Curves showing the relationship between absorption performance and frequency in the 2–18 GHz frequency range;

[0045] Figure 20 This invention provides a neodymium-tantalum dual-substituted M-type barium ferrite dual-band absorbing agent, Ba, obtained in Example 6 of this invention. 0.9 Nd 0.1 Fe 11.8 Ta 0.2 O 19 The graph shows the relationship between absorption performance and frequency in the frequency range of 26.5 to 40 GHz.

[0046] Figure 21 This invention provides a neodymium-tantalum dual-substituted M-type barium ferrite dual-band absorbing agent, Ba, obtained in Example 7 of this invention. 0.8 Nd 0.2 Fe 11.9Ta 0.1 O 19 XRD patterns;

[0047] Figure 22 This invention provides a neodymium-tantalum dual-substituted M-type barium ferrite dual-band absorbing agent, Ba, obtained in Example 7 of this invention. 0.8 Nd 0.2 Fe 11.9 Ta 0.1 O 19 Curves showing the relationship between absorption performance and frequency in the 2–18 GHz frequency range;

[0048] Figure 23 This invention provides a neodymium-tantalum dual-substituted M-type barium ferrite dual-band absorbing agent, Ba, obtained in Example 7 of this invention. 0.8 Nd 0.2 Fe 11.9 Ta 0.1 O 19 The graph shows the relationship between absorption performance and frequency in the frequency range of 26.5 to 40 GHz.

[0049] Figure 24 This invention provides a neodymium-tantalum dual-substituted M-type barium ferrite dual-band absorbing agent, Ba, obtained in Example 8 of this invention. 0.7 Nd 0.3 Fe 11.7 Ta 0.3 O 19 XRD patterns;

[0050] Figure 25 This invention provides a neodymium-tantalum dual-substituted M-type barium ferrite dual-band absorbing agent, Ba, obtained in Example 8 of this invention. 0.7 Nd 0.3 Fe 11.7 Ta 0.3 O 19 Curves showing the relationship between absorption performance and frequency in the 2–18 GHz frequency range;

[0051] Figure 26 This invention provides a neodymium-tantalum dual-substituted M-type barium ferrite dual-band absorbing agent, Ba, obtained in Example 8 of this invention. 0.7 Nd 0.3 Fe 11.7 Ta 0.3 O 19 The graph shows the relationship between absorption performance and frequency in the frequency range of 26.5 to 40 GHz.

[0052] Figure 27 This invention provides a neodymium-substituted M-type barium ferrite dual-band absorbing agent, Ba, obtained as Comparative Example 1. 0.8 Nd 0.2 Fe 12O 19 XRD patterns;

[0053] Figure 28 This invention provides a neodymium-substituted M-type barium ferrite dual-band absorbing agent, Ba, obtained as Comparative Example 1. 0.8 Nd 0.2 Fe 12 O 19 Curves showing the relationship between absorption performance and frequency in the 2–18 GHz frequency range;

[0054] Figure 29 This invention provides a neodymium-substituted M-type barium ferrite dual-band absorbing agent, Ba, obtained as Comparative Example 1. 0.8 Nd 0.2 Fe 12 O 19 The graph shows the relationship between absorption performance and frequency in the frequency range of 26.5 to 40 GHz. Detailed Implementation

[0055] The embodiments of the present invention will now be described in detail with reference to the accompanying drawings. Obviously, the embodiments shown in this invention are only some embodiments of the invention, and not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of this invention.

[0056] Example 1

[0057] A method for preparing a rare-earth neodymium and pentavalent ion-substituted M-type barium ferrite dual-band microwave absorber includes the following steps:

[0058] (1) Barium carbonate, neodymium oxide, iron oxide, and niobium oxide were placed in a mortar in a molar ratio of 0.9:0.05:5.45:0.05 and boron oxide accounting for 1% of the total mass of barium carbonate, neodymium oxide, iron oxide, and niobium oxide. The mixture was ground for 30 min to obtain a premixed precursor.

[0059] (2) Place the fully premixed precursor obtained in step (1) into a zirconia ball mill jar, add an appropriate amount of anhydrous ethanol, then install the ball mill jar and ball mill at a speed of 300 rpm. After ball milling for 24 hours, take out the ball milled powder and dry it at 60°C for later use.

[0060] (3) Grind the ball mill powder obtained in step (2) for 10 min, take a sample for the first calcination, the calcination temperature is 1400℃, the calcination time is 4 h, and the heating rate is 10℃ / min.

[0061] (4) After grinding the sample obtained in step (3), a second ball milling is performed. The ball milling speed is also set to 300 rpm. After ball milling for 12 hours, the ball milled powder is taken out and dried at 60°C for later use.

[0062] (5) The sample obtained in step (4) is calcined for the second time at a temperature of 1400℃ for 4 hours and a heating rate of 10℃ / min. After cooling to room temperature, the sample is ground for 30 minutes to obtain rare earth neodymium and pentavalent niobium ion double-substituted M-type barium ferrite dual-band microwave absorber.

[0063] The microwave absorption performance of the rare-earth neodymium and pentavalent niobium ion-substituted M-type barium ferrite dual-band microwave absorber prepared in this embodiment was tested using a vector network analyzer. During testing, the microwave absorbing material powder of this invention was mixed with solid paraffin at a mass ratio of 8:2 to prepare cyclic and blocky paraffin samples, which were then tested in two wavelength ranges: 2–18 GHz and 26.5–40 GHz, respectively.

[0064] Figure 1 It is a neodymium-niobium dual-substituted M-type barium ferrite dual-band microwave absorber Ba 0.9 Nd 0.1 Fe 11.9 Nb 0.1 O 19 The XRD pattern shows that Example 1 obtained a high-purity M-type barium ferrite phase, indicating that the rare earth element Nd... 3+ Ionic and nonmagnetic Nb 5+ The ions successfully substituted into the M-type barium ferrite matrix. Figure 2 The exhibit is Ba 0.9 Nd 0.1 Fe 11.9 Nb 0.1 O 19 The XPS high-resolution spectrum of Nb was fitted with peaks to obtain two peaks at 206.64 eV and 209.47 eV, corresponding to Nb, respectively. 5+ 3D 5 / 2 and Nb 5+ 3D 3 / 2 This indicates that Nb is substituted in the form of pentavalent ions. Figure 3 and Figure 4 These are the microwave absorbing agents Ba obtained in Example 1. 0.9 Nd 0.1 Fe 11.9 Nb 0.1 O 19 The curves showing the relationship between absorption performance and frequency in the 2–18 GHz and 26.5–40 GHz frequency bands. Figure 3The absorption performance data obtained are for matching thicknesses of 1.3mm and 1.425mm. As shown in the figure, an effective absorption bandwidth of 3.8GHz can be obtained when the matching thickness is 1.425mm; while when the matching thickness is 1.3mm, the maximum reflection loss value of -14.98dB is obtained at 17.52GHz. Figure 4 The figure shows the high-frequency absorption performance obtained when the matching thickness is 0.55mm and 0.65mm. As can be seen from the figure, when the matching thickness is 0.65mm, an effective absorption bandwidth of 7.22GHz can be obtained; while when the matching thickness is 0.55mm, the maximum reflection loss value of -31.3dB is obtained at 38GHz.

[0065] Example 2

[0066] A method for preparing a rare-earth neodymium and pentavalent ion-substituted M-type barium ferrite dual-band microwave absorber includes the following steps:

[0067] (1) Barium carbonate, neodymium oxide, iron oxide, and niobium oxide were placed in a mortar in a molar ratio of 0.9:0.05:5.4:0.1 and boron oxide accounting for 1% of the total mass of barium carbonate, neodymium oxide, iron oxide, and niobium oxide was ground for 30 min to obtain a premixed precursor.

[0068] (2) Place the fully premixed precursor obtained in step (1) into a zirconia ball mill jar, add an appropriate amount of anhydrous ethanol, then install the ball mill jar and ball mill at a speed of 300 rpm. After ball milling for 24 hours, take out the ball milled powder and dry it at 60°C for later use.

[0069] (3) Grind the ball mill powder obtained in step (2) for 10 min, take a sample for the first calcination, the calcination temperature is 1400℃, the calcination time is 4 h, and the heating rate is 10℃ / min.

[0070] (4) After grinding the sample obtained in step (3), a second ball milling is performed. The ball milling speed is also set to 300 rpm. After ball milling for 12 hours, the ball milled powder is taken out and dried at 60°C for later use.

[0071] (5) The sample obtained in step (4) is calcined for the second time at a temperature of 1400℃ for 4 hours and a heating rate of 10℃ / min. After cooling to room temperature, the sample is ground for 30 minutes to obtain rare earth neodymium and pentavalent niobium ion double-substituted M-type barium ferrite dual-band microwave absorber.

[0072] The microwave absorption performance of the rare-earth neodymium and pentavalent niobium ion-substituted M-type barium ferrite dual-band microwave absorber prepared in this embodiment was tested using a vector network analyzer. During testing, the microwave absorbing material powder of this invention was mixed with solid paraffin at a mass ratio of 8:2 to prepare cyclic and blocky paraffin samples, which were then tested in two wavelength ranges: 2–18 GHz and 26.5–40 GHz, respectively.

[0073] Figure 5 It is a neodymium-niobium dual-substituted M-type barium ferrite dual-band microwave absorber Ba 0.9 Nd 0.1 Fe 11.8 Nb 0.2 O 19 The XRD pattern shows that Example 2 obtained a high-purity M-type barium ferrite phase, indicating that the rare earth element Nd... 3+ Ionic and nonmagnetic Nb 5+ The ions successfully substituted into the M-type barium ferrite matrix. Figure 6 and Figure 7 The absorbing agent Ba obtained in Example 2 is respectively 0.9 Nd 0.1 Fe 11.8 Nb 0.2 O 19 The curves showing the relationship between absorption performance and frequency in the 2–18 GHz and 26.5–40 GHz frequency bands. Figure 6 The absorption performance data obtained are for matching thicknesses of 1.25mm and 4.35mm. As shown in the figure, an effective absorption bandwidth of 1.96GHz can be obtained when the matching thickness is 1.25mm; while when the matching thickness is 4.35mm, the maximum reflection loss value of -14.9dB is obtained at 14.12GHz. Figure 7 The figure shows the high-frequency absorption performance obtained when the matching thickness is 0.65 mm and 0.725 mm. As can be seen from the figure, when the matching thickness is 0.725 mm, an effective absorption bandwidth of 12.52 GHz can be obtained; while when the matching thickness is 0.65 mm, the maximum reflection loss value of -35.33 dB is obtained at 31.5 GHz.

[0074] Example 3

[0075] A method for preparing a rare-earth neodymium and pentavalent ion-substituted M-type barium ferrite dual-band microwave absorber includes the following steps:

[0076] (1) Barium carbonate, neodymium oxide, iron oxide, and niobium oxide were placed in a mortar in a molar ratio of 0.8:0.1:5.45:0.05 and boron oxide accounting for 1% of the total mass of barium carbonate, neodymium oxide, iron oxide, and niobium oxide. The mixture was ground for 30 min to obtain a premixed precursor.

[0077] (2) Place the fully premixed precursor obtained in step (1) into a zirconia ball mill jar, add an appropriate amount of anhydrous ethanol, then install the ball mill jar and ball mill at a speed of 300 rpm. After ball milling for 24 hours, take out the ball milled powder and dry it at 60°C for later use.

[0078] (3) Grind the ball mill powder obtained in step (2) for 10 min, take a sample for the first calcination, the calcination temperature is 1400℃, the calcination time is 4 h, and the heating rate is 10℃ / min.

[0079] (4) After grinding the sample obtained in step (3), a second ball milling is performed. The ball milling speed is also set to 300 rpm. After ball milling for 12 hours, the ball milled powder is taken out and dried at 60°C for later use.

[0080] (5) The sample obtained in step (4) is calcined for the second time at a temperature of 1400℃ for 4 hours and a heating rate of 10℃ / min. After cooling to room temperature, the sample is ground for 30 minutes to obtain rare earth neodymium and pentavalent niobium ion double-substituted M-type barium ferrite dual-band microwave absorber.

[0081] The microwave absorption performance of the rare-earth neodymium and pentavalent niobium ion-substituted M-type barium ferrite dual-band microwave absorber prepared in this embodiment was tested using a vector network analyzer. During testing, the microwave absorbing material powder of this invention was mixed with solid paraffin at a mass ratio of 8:2 to prepare cyclic and blocky paraffin samples, which were then tested in two wavelength ranges: 2–18 GHz and 26.5–40 GHz, respectively.

[0082] Figure 8 It is a neodymium-niobium dual-substituted M-type barium ferrite dual-band microwave absorber Ba 0.8 Nd 0.2 Fe 11.9 Nb 0.1 O 19 The XRD pattern shows that Example 3 obtained a high-purity M-type barium ferrite phase, indicating that the rare earth element Nd... 3+ Ionic and nonmagnetic Nb 5+ The ions successfully substituted into the M-type barium ferrite matrix. Figure 9 and Figure 10 The absorbing agent Ba obtained in Example 3 is respectively 0.8 Nd 0.2 Fe 11.9 Nb 0.1 O 19 The curves showing the relationship between absorption performance and frequency in the 2–18 GHz and 26.5–40 GHz frequency bands. Figure 9The absorption performance data were obtained with matching thicknesses of 1.2mm and 1.3mm. As shown in the figure, an effective absorption bandwidth of 2.6GHz can be obtained when the matching thickness is 1.3mm; while the maximum reflection loss value of -13.16dB is obtained at 18GHz when the matching thickness is 1.2mm. Figure 10 The figure shows the high-frequency absorption performance obtained when the matching thickness is 0.575mm and 0.675mm. As can be seen from the figure, when the matching thickness is 0.675mm, an effective absorption bandwidth of 8.81GHz can be obtained; while when the matching thickness is 0.675mm, the maximum reflection loss value of -33.89dB is obtained at 36.96GHz.

[0083] Example 4

[0084] A method for preparing a rare-earth neodymium and pentavalent ion-substituted M-type barium ferrite dual-band microwave absorber includes the following steps:

[0085] (1) Barium carbonate, neodymium oxide, iron oxide, and niobium oxide were placed in a mortar in a molar ratio of 0.7:0.15:5.35:0.15 and boron oxide accounting for 1% of the total mass of barium carbonate, neodymium oxide, iron oxide, and niobium oxide. The mixture was ground for 30 min to obtain a premixed precursor.

[0086] (2) Place the fully premixed precursor obtained in step (1) into a zirconia ball mill jar, add an appropriate amount of anhydrous ethanol, then install the ball mill jar and ball mill at a speed of 300 rpm. After ball milling for 24 hours, take out the ball milled powder and dry it at 60°C for later use.

[0087] (3) Grind the ball mill powder obtained in step (2) for 10 min, take a sample for the first calcination, the calcination temperature is 1400℃, the calcination time is 4 h, and the heating rate is 10℃ / min.

[0088] (4) After grinding the sample obtained in step (3), a second ball milling is performed. The ball milling speed is also set to 300 rpm. After ball milling for 12 hours, the ball milled powder is taken out and dried at 60°C for later use.

[0089] (5) The sample obtained in step (4) is calcined for the second time at a temperature of 1400℃ for 4 hours and a heating rate of 10℃ / min. After cooling to room temperature, the sample is ground for 30 minutes to obtain rare earth neodymium and pentavalent niobium ion double-substituted M-type barium ferrite dual-band microwave absorber.

[0090] The microwave absorption performance of the rare-earth neodymium and pentavalent niobium ion-substituted M-type barium ferrite dual-band microwave absorber prepared in this embodiment was tested using a vector network analyzer. During testing, the microwave absorbing material powder of this invention was mixed with solid paraffin at a mass ratio of 8:2 to prepare cyclic and blocky paraffin samples, which were then tested in two wavelength ranges: 2–18 GHz and 26.5–40 GHz, respectively.

[0091] Figure 11 It is a neodymium-niobium dual-substituted M-type barium ferrite dual-band microwave absorber Ba 0.7 Nd 0.3 Fe 11.7 Nb 0.3 O 19 The XRD pattern indicates that the M-type barium ferrite phase was successfully obtained in Example 4, but small amounts of α-Fe2O3, BaFe2O4, and BaNb were present. m O n The phase composition indicates that although rare earth element Nd... 3+ Ionic and nonmagnetic Nb 5+ Ions can be substituted into the M-type barium ferrite, but in Example 4, the substitution ratio of neodymium and niobium was too high, and they could not be completely dissolved in the M-type barium ferrite phase. Figure 12 and Figure 13 The absorbing agent Ba obtained in Example 4 is respectively 0.7 Nd 0.3 Fe 11.7 Nb 0.3 O 19 The curves showing the relationship between absorption performance and frequency in the 2–18 GHz and 26.5–40 GHz frequency bands. Figure 12 The absorption performance data obtained are for matching thicknesses of 3.475mm and 4.55mm. As shown in the figure, an effective absorption bandwidth of 2GHz can be obtained when the matching thickness is 3.475mm; while when the matching thickness is 4.55mm, the maximum reflection loss value of -18.04dB is obtained at 12.84GHz. Figure 13 The figure shows the high-frequency absorption performance obtained when the matching thickness is 0.675 mm and 0.7 mm. As can be seen from the figure, both the matching thickness of 0.675 mm and 0.7 mm can effectively absorb electromagnetic waves in the entire 26.5-40 GHz band, i.e., the absorption bandwidth of 13.5 GHz. Furthermore, when the matching thickness is 0.7 mm, the maximum reflection loss value of -47.08 dB is obtained at 28.26 GHz.

[0092] Example 5

[0093] A method for preparing a rare-earth neodymium / pentavalent ion double-substituted M-type barium ferrite dual-band microwave absorber includes the following steps:

[0094] (1) Barium carbonate, neodymium oxide, iron oxide, and tantalum oxide were placed in a mortar in a molar ratio of 0.9:0.05:5.45:0.05 and boron oxide accounting for 1% of the total mass of barium carbonate, neodymium oxide, iron oxide, and tantalum oxide. The mixture was ground for 30 minutes to obtain a premixed precursor.

[0095] (2) Place the fully premixed precursor obtained in step (1) into a zirconia ball mill jar, add an appropriate amount of anhydrous ethanol, then install the ball mill jar and ball mill at a speed of 300 rpm. After ball milling for 24 hours, take out the ball milled powder and dry it at 60°C for later use.

[0096] (3) Grind the ball mill powder obtained in step (2) for 10 min, take a sample for the first calcination, the calcination temperature is 1400℃, the calcination time is 4 h, and the heating rate is 10℃ / min.

[0097] (4) After grinding the sample obtained in step (3), a second ball milling is performed. The ball milling speed is also set to 300 rpm. After ball milling for 12 hours, the ball milled powder is taken out and dried at 60°C for later use.

[0098] (5) The sample obtained in step (4) is calcined for the second time at a temperature of 1400℃ for 4 hours and a heating rate of 10℃ / min. After cooling to room temperature, the sample is ground for 30 minutes to obtain rare earth neodymium and pentavalent tantalum ion double-substituted M-type barium ferrite dual-band microwave absorber.

[0099] The microwave absorption performance of the rare-earth neodymium and pentavalent tantalum ion-substituted M-type barium ferrite dual-band microwave absorber prepared in this embodiment was tested using a vector network analyzer. During testing, the microwave absorbing material powder of this invention was mixed with solid paraffin at a mass ratio of 8:2 to prepare cyclic and blocky paraffin samples, which were then tested in two wavelength ranges: 2–18 GHz and 26.5–40 GHz, respectively.

[0100] Figure 14 It is a neodymium-tantalum dual-substituted M-type barium ferrite dual-band microwave absorber Ba 0.9 Nd 0.1 Fe 11.9 Ta 0.1 O 19 The XRD pattern shows that Example 5 obtained a high-purity M-type barium ferrite phase, indicating that the rare earth element Nd... 3+ Ionic and nonmagnetic Ta 5+ The ions successfully substituted into the M-type barium ferrite matrix. Figure 15 The exhibit is Ba 0.9 Nd 0.1 Fe 11.9 Ta 0.1 O 19The XPS high-resolution spectrum of Ta was obtained by peak fitting, yielding two peaks at 25.59 and 27.55 eV, corresponding to Ta, respectively. 5+ 4f 7 / 2 and Ta 5+ 4f 5 / 2 This indicates that the Ta element is substituted in the form of pentavalent ions. Figure 16 and Figure 17 The absorbing agent Ba obtained in Example 5 is respectively 0.9 Nd 0.1 Fe 11.9 Ta 0.1 O 19 The curves showing the relationship between absorption performance and frequency in the 2–18 GHz and 26.5–40 GHz frequency bands. Figure 16 The absorption performance data obtained are for matching thicknesses of 1.35mm and 1.85mm. As shown in the figure, an effective absorption bandwidth of 2.8GHz can be obtained when the matching thickness is 1.35mm; while when the matching thickness is 1.85mm, the maximum reflection loss value of -14.36dB is obtained at 11.8GHz. Figure 17 The figure shows the high-frequency absorption performance obtained when the matching thickness is 0.575mm and 0.675mm. As can be seen from the figure, when the matching thickness is 0.675mm, an effective absorption bandwidth of 9.11GHz can be obtained; while when the matching thickness is 0.575mm, the maximum reflection loss value of -32.02dB is obtained at 36.52GHz.

[0101] Example 6

[0102] A method for preparing a rare-earth neodymium and pentavalent ion-substituted M-type barium ferrite dual-band microwave absorber includes the following steps:

[0103] (1) Barium carbonate, neodymium oxide, iron oxide, and tantalum oxide were placed in a mortar in a molar ratio of 0.9:0.05:5.4:0.1 and boron oxide accounting for 1% of the total mass of barium carbonate, neodymium oxide, iron oxide, and tantalum oxide was ground for 30 min to obtain a premixed precursor.

[0104] (2) Place the fully premixed precursor obtained in step (1) into a zirconia ball mill jar, add an appropriate amount of anhydrous ethanol, then install the ball mill jar and ball mill at a speed of 300 rpm. After ball milling for 24 hours, take out the ball milled powder and dry it at 60°C for later use.

[0105] (3) Grind the ball mill powder obtained in step (2) for 10 min, take a sample for the first calcination, the calcination temperature is 1400℃, the calcination time is 4 h, and the heating rate is 10℃ / min.

[0106] (4) After grinding the sample obtained in step (3), a second ball milling is performed. The ball milling speed is also set to 300 rpm. After ball milling for 12 hours, the ball milled powder is taken out and dried at 60°C for later use.

[0107] (5) The sample obtained in step (4) is calcined for the second time at a temperature of 1400℃ for 4 hours and a heating rate of 10℃ / min. After cooling to room temperature, the sample is ground for 30 minutes to obtain rare earth neodymium and pentavalent tantalum ion double-substituted M-type barium ferrite dual-band microwave absorber.

[0108] The microwave absorption performance of the rare-earth neodymium and pentavalent tantalum ion-substituted M-type barium ferrite dual-band microwave absorber prepared in this embodiment was tested using a vector network analyzer. During testing, the microwave absorbing material powder of this invention was mixed with solid paraffin at a mass ratio of 8:2 to prepare cyclic and blocky paraffin samples, which were then tested in two wavelength ranges: 2–18 GHz and 26.5–40 GHz, respectively.

[0109] Figure 18 It is a neodymium-tantalum dual-substituted M-type barium ferrite dual-band microwave absorber Ba 0.9 Nd 0.1 Fe 11.8 Ta 0.2 O 19 The XRD pattern shows that Example 6 obtained a high-purity M-type barium ferrite phase, indicating that the rare earth element Nd... 3+ Ionic and nonmagnetic Ta 5+ The ions successfully substituted into the M-type barium ferrite matrix. Figure 19 and Figure 20 These are the microwave absorbing agents Ba obtained in Example 6. 0.9 Nd 0.1 Fe 11.8 Ta 0.2 O 19 The curves showing the relationship between absorption performance and frequency in the 2–18 GHz and 26.5–40 GHz frequency bands. Figure 19 The absorption performance data obtained are for matching thicknesses of 3.5mm and 3.775mm. As shown in the figure, an effective absorption bandwidth of 1.88GHz can be obtained when the matching thickness is 3.5mm; while when the matching thickness is 3.775mm, the maximum reflection loss value of -23.62dB is obtained at 15.76GHz. Figure 20 The figure shows the high-frequency absorption performance obtained when the matching thickness is 0.675mm and 0.75mm. As can be seen from the figure, when the matching thickness is 0.75mm, an effective absorption bandwidth of 13.23GHz can be obtained; while when the matching thickness is 0.675mm, the maximum reflection loss value of -38.99dB is obtained at 30.01GHz.

[0110] Example 7

[0111] A method for preparing a rare-earth neodymium and pentavalent ion-substituted M-type barium ferrite dual-band microwave absorber includes the following steps:

[0112] (1) Barium carbonate, neodymium oxide, iron oxide, and tantalum oxide were placed in a mortar in a molar ratio of 0.8:0.1:5.45:0.05 and boron oxide accounting for 1% of the total mass of barium carbonate, neodymium oxide, iron oxide, and tantalum oxide. The mixture was ground for 30 minutes to obtain a premixed precursor.

[0113] (2) Place the fully premixed precursor obtained in step (1) into a zirconia ball mill jar, add an appropriate amount of anhydrous ethanol, then install the ball mill jar and ball mill at a speed of 300 rpm. After ball milling for 24 hours, take out the ball milled powder and dry it at 60°C for later use.

[0114] (3) Grind the ball mill powder obtained in step (2) for 10 min, take a sample for the first calcination, the calcination temperature is 1400℃, the calcination time is 4 h, and the heating rate is 10℃ / min.

[0115] (4) After grinding the sample obtained in step (3), a second ball milling is performed. The ball milling speed is also set to 300 rpm. After ball milling for 12 hours, the ball milled powder is taken out and dried at 60°C for later use.

[0116] (5) The sample obtained in step (4) is calcined for the second time at a temperature of 1400℃ for 4 hours and a heating rate of 10℃ / min. After cooling to room temperature, the sample is ground for 30 minutes to obtain rare earth neodymium and pentavalent tantalum ion double-substituted M-type barium ferrite dual-band microwave absorber.

[0117] The microwave absorption performance of the rare-earth neodymium and pentavalent tantalum ion-substituted M-type barium ferrite dual-band microwave absorber prepared in this embodiment was tested using a vector network analyzer. During testing, the microwave absorbing material powder of this invention was mixed with solid paraffin at a mass ratio of 8:2 to prepare cyclic and blocky paraffin samples, which were then tested in two wavelength ranges: 2–18 GHz and 26.5–40 GHz, respectively.

[0118] Figure 21 It is a neodymium-tantalum dual-substituted M-type barium ferrite dual-band microwave absorber Ba 0.8 Nd 0.2 Fe 11.9 Ta 0.1 O 19 The XRD pattern shows that Example 7 obtained a high-purity M-type barium ferrite phase, indicating that the rare earth element Nd... 3+ Ionic and nonmagnetic Ta 5+The ions successfully substituted into the M-type barium ferrite matrix. Figure 22 and Figure 23 The absorbing agent Ba obtained in Example 7 is respectively 0.8 Nd 0.2 Fe 11.9 Ta 0.1 O 19 The curves showing the relationship between absorption performance and frequency in the 2–18 GHz and 26.5–40 GHz frequency bands. Figure 22 The absorption performance data were obtained with matching thicknesses of 1.275mm and 1.625mm. As shown in the figure, an effective absorption bandwidth of 2.32GHz can be obtained when the matching thickness is 1.275mm; while the maximum reflection loss value of -13.12dB is obtained at 13.16GHz when the matching thickness is 1.625mm. Figure 23 The figure shows the high-frequency absorption performance obtained when the matching thickness is 0.575mm and 0.675mm. As can be seen from the figure, when the matching thickness is 0.675mm, an effective absorption bandwidth of 9.42GHz can be obtained; while when the matching thickness is 0.575mm, the maximum reflection loss value of -35.11dB is obtained at 35.95GHz.

[0119] Example 8

[0120] A method for preparing a rare-earth neodymium and pentavalent ion-substituted M-type barium ferrite dual-band microwave absorber includes the following steps:

[0121] (1) Barium carbonate, neodymium oxide, iron oxide, and tantalum oxide were placed in a mortar in a molar ratio of 0.7:0.15:5.35:0.15 and boron oxide accounting for 1% of the total mass of barium carbonate, neodymium oxide, iron oxide, and tantalum oxide. The mixture was ground for 30 minutes to obtain a premixed precursor.

[0122] (2) Place the fully premixed precursor obtained in step (1) into a zirconia ball mill jar, add an appropriate amount of anhydrous ethanol, then install the ball mill jar and ball mill at a speed of 300 rpm. After ball milling for 24 hours, take out the ball milled powder and dry it at 60°C for later use.

[0123] (3) Grind the ball mill powder obtained in step (2) for 10 min, take a sample for the first calcination, the calcination temperature is 1400℃, the calcination time is 4 h, and the heating rate is 10℃ / min;

[0124] (4) After grinding the sample obtained in step (3), a second ball milling is performed. The ball milling speed is also set to 300 rpm. After ball milling for 12 hours, the ball milled powder is taken out and dried at 60°C for later use.

[0125] (5) The sample obtained in step (4) is calcined for the second time at a temperature of 1400℃ for 4 hours and a heating rate of 10℃ / min. After cooling to room temperature, the sample is ground for 30 minutes to obtain rare earth neodymium and pentavalent tantalum ion double-substituted M-type barium ferrite dual-band microwave absorber.

[0126] The microwave absorption performance of the rare earth element neodymium and pentavalent tantalum ion-substituted M-type barium ferrite dual-band microwave absorber prepared in this embodiment was tested using a vector network analyzer. During testing, the microwave absorbing material powder of this invention was mixed with solid paraffin at a mass ratio of 8:2 to prepare cyclic and blocky paraffin samples, which were then tested in two wavelength ranges: 2–18 GHz and 26.5–40 GHz, respectively.

[0127] Figure 24 It is a neodymium-tantalum dual-substituted M-type barium ferrite dual-band microwave absorber Ba 0.7 Nd 0.3 Fe 11.7 Ta 0.3 O 19 The XRD pattern indicates that Example 8 successfully obtained the M-type barium ferrite phase, but there were small amounts of α-Fe2O3, BaFe2O4, and BaTa4O. 11 This indicates that although rare earth element Nd 3+ Ionic and nonmagnetic Ta 5+ Ions can be substituted into the M-type barium ferrite, but in Example 8, the substitution of neodymium and tantalum elements was too high, and they could not be completely dissolved by the M-type barium ferrite phase. Figure 25 and Figure 26 The absorbing agent Ba obtained in Example 8 is respectively 0.7 Nd 0.3 Fe 11.7 Ta 0.3 O 19 The curves showing the relationship between absorption performance and frequency in the 2–18 GHz and 26.5–40 GHz frequency bands. Figure 25 The absorption performance data obtained are for matching thicknesses of 3.425mm and 4.55mm. As shown in the figure, an effective absorption bandwidth of 1.84GHz can be obtained when the matching thickness is 3.425mm; while the maximum reflection loss value of -19.27dB is obtained at 12.84GHz when the matching thickness is 4.55mm. Figure 26The figure shows the high-frequency absorption performance obtained when the matching thickness is 0.65mm and 0.725mm. As can be seen from the figure, both 0.65mm and 0.725mm can effectively absorb electromagnetic waves in the entire 26.5~40GHz band, i.e., the absorption bandwidth is 13.5GHz. When the matching thickness is 0.725mm, the maximum reflection loss value of -34.84dB is obtained at 26.64GHz.

[0128] Comparative Example 1

[0129] A method for preparing a rare-earth neodymium unit-substituted M-type barium ferrite dual-band microwave absorber includes the following steps:

[0130] (1) Barium carbonate, neodymium oxide, and iron oxide were placed in a mortar with a molar ratio of 0.8:0.1:5.5 and boron oxide accounting for 1% of the total mass of barium carbonate, neodymium oxide, and iron oxide. The mixture was ground for 30 minutes to obtain a premixed precursor.

[0131] (2) Place the fully premixed precursor obtained in step (1) into a zirconia ball mill jar, add an appropriate amount of anhydrous ethanol, then install the ball mill jar and ball mill at a speed of 300 rpm. After ball milling for 24 hours, take out the ball milled powder and dry it at 60°C for later use.

[0132] (3) Grind the ball mill powder obtained in step (2) for 10 min, take a sample for the first calcination, the calcination temperature is 1400℃, the calcination time is 4 h, and the heating rate is 10℃ / min.

[0133] (4) After grinding the sample obtained in step (3), a second ball milling is performed. The ball milling speed is also set to 300 rpm. After ball milling for 12 hours, the ball milled powder is taken out and dried at 60°C for later use.

[0134] (5) The sample obtained in step (4) is calcined for the second time at a temperature of 1400℃ for 4 hours and a heating rate of 10℃ / min. After cooling to room temperature, the sample is ground for 30 minutes to obtain rare earth neodymium unit-substituted M-type barium ferrite dual-band microwave absorber.

[0135] The microwave absorption performance of the rare-earth element neodymium-substituted M-type barium ferrite dual-band microwave absorber prepared in this embodiment was tested using a vector network analyzer. During testing, the microwave absorbing material powder of this invention was mixed with solid paraffin at a mass ratio of 8:2 to prepare cyclic and blocky paraffin samples, which were then tested in two wavelength ranges: 2–18 GHz and 26.5–40 GHz, respectively.

[0136] Figure 27 It is a neodymium-substituted M-type barium ferrite dual-band absorbing agent Ba. 0.8 Nd0.2 Fe 12 O 19 The XRD pattern shows that Comparative Example 1 obtained a high-purity M-type barium ferrite phase, indicating that the rare earth element Nd... 3+ The ions successfully substituted into the M-type barium ferrite matrix. Figure 28 and Figure 29 These are the microwave absorbing agents Ba obtained in Comparative Example 1. 0.8 Nd 0.2 Fe 12 O 19 The curves showing the relationship between absorption performance and frequency in the 2–18 GHz and 26.5–40 GHz frequency bands. Figure 28 The absorption performance data obtained are for matching thicknesses of 1.7mm and 3.95mm. As shown in the figure, an effective absorption bandwidth of 2.04GHz can be obtained when the matching thickness is 3.95mm; while when the matching thickness is 1.7mm, the maximum reflection loss value of -13.32dB is obtained at 13.44GHz. Figure 29 The figure shows the high-frequency absorption performance obtained when the matching thickness is 0.625mm and 0.725mm. As can be seen from the figure, when the matching thickness is 0.725mm, an effective absorption bandwidth of 6.78GHz can be obtained; while when the matching thickness is 0.625mm, the maximum reflection loss value of -16.55dB is obtained at 40GHz.

[0137] The above embodiments are typical examples of the present invention and are not intended to limit the invention in any way. For example, the ball milling speed, ball milling time, calcination temperature, calcination time, and boron oxide content can all be further adjusted. Therefore, based on the overall concept of the present invention, any adjustments or modifications to the process parameters described by those skilled in the art, as long as they do not deviate from the inventive concept or exceed the scope defined in these claims, should fall within the protection scope of the present invention.

[0138] The above description is merely an example and illustration of the structure of the present invention. Those skilled in the art can make various modifications or additions to the specific embodiments described, or use similar methods to replace them, as long as they do not deviate from the structure of the present invention or exceed the scope defined in the claims, all of which should fall within the protection scope of the present invention.

Claims

1. A rare-earth neodymium and pentavalent ion-substituted M-type barium ferrite dual-band microwave absorber, characterized in that: The aforementioned dual-substituted M-type barium ferrite dual-band absorbing agent is Ba 1-x Nd x Fe 12-y A y O 19 Where A is at least one of the pentavalent transition metal ions Nb and Ta, x = 0.05–0.3, y = 0.05–0.3, and the rare earth element neodymium and the pentavalent transition metal ion A respectively replace part of the Ba in the M-type barium ferrite. 2+ Ions and some Fe 3+ Ions enable the simultaneous substitution of two elements.

2. A method for preparing the rare-earth neodymium and pentavalent ion-substituted M-type barium ferrite dual-band microwave absorber according to claim 1, characterized in that, Includes the following steps: (1) Barium carbonate, neodymium oxide, iron oxide, oxide of A and boron oxide are mixed and ground in a preset ratio to obtain a premixed precursor; (2) The premixed precursor obtained in step (1) is placed in a zirconia ball mill jar, and then an appropriate amount of anhydrous ethanol is added for ball milling. After ball milling, the powder is dried to obtain the ball milled powder. (3) After grinding the ball mill powder obtained in step (2), it is subjected to the first calcination; (4) After grinding the sample obtained in step (3), perform a second ball milling; (5) The sample obtained in step (4) is calcined for the second time. After cooling to room temperature, the sample is thoroughly ground to finally obtain rare earth neodymium and pentavalent ion double-substituted M-type barium ferrite dual-band absorbing agent.

3. The preparation method according to claim 2, characterized in that: In step (1), the amount of boron oxide added is 1 to 3% of the total mass of barium carbonate, neodymium oxide, iron oxide and oxide of A.

4. The preparation method according to claim 2, characterized in that: In step (2), the ball milling speed is 250-400 rpm, the ball milling time is 12-36 h, and the drying temperature is 60℃.

5. The preparation method according to claim 2, characterized in that: In step (3), the temperature of the first calcination is 1100-1400℃, the calcination time is 4-8 h, and the heating rate is 10℃ / min.

6. The preparation method according to claim 2, characterized in that: In step (4), the second ball milling speed is 250-400 rpm, the ball milling time is 12-18 h, and the drying temperature is 60℃.

7. The preparation method according to claim 2, characterized in that: In step (5), the temperature of the second calcination is 1100 to 1400℃, the calcination time is 4 to 8 h, and the heating rate is 10℃ / min.

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