A rare earth neodymium / transition metal ion double-site substituted M-type barium ferrite wave-absorbing powder material and a preparation method thereof

Abstract

The application discloses a rare earth neodymium / transition metal ion double-site substituted M-type barium ferrite wave-absorbing powder material and a preparation method thereof. 1‑x Nd x Fe 12‑x A x O 19 , wherein A is Zn, Co, Ni, Ti or Zr, and x=0.02-0.3. The preparation method comprises the following steps: substituting a rare earth element neodymium and transition metal ions A into Ba 2+ and Fe 3+ sites of M-type barium ferrite respectively to simultaneously substitute different element sites in the M-type barium ferrite, and obtain the M-type barium ferrite wave-absorbing powder material substituted by the rare earth element neodymium ion and the transition metal ion, wherein the transition metal ion A is Zn 2+ , Co 2+ , Ni 2+ , Ti 4+ or Zr 4+ . The application can improve electromagnetic parameters of the M-type barium ferrite, and obtain a high-efficiency wave-absorbing powder material capable of being applied in double frequency bands.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of wave-absorbing materials, and particularly relates to a rare earth neodymium / transition metal ion double-site substituted M-type barium ferrite wave-absorbing powder material and a preparation method thereof. BACKGROUND

[0002] M-type barium ferrite is a hexagonal crystal structure ferrimagnetic oxide, has good chemical stability and corrosion resistance, and has high uniaxial magnetocrystalline anisotropy, easy magnetization axis parallel to the c-axis, large coercivity and magnetic energy product, and also has low cost and strong environmental adaptability. M-type barium ferrite has been widely used in many fields, such as aerospace, magnetic recording medium, weapon stealth, computer, electromagnetic radiation resistance and medical instrument, etc. With the rapid development of 5G technology and the iterative update of military defense equipment, M-type barium ferrite with good magnetism has important significance in the research and application of the electromagnetic wave absorption field.

[0003] However, the pure phase M-type barium ferrite has too high intrinsic resonance frequency (about 45 GHz), which is higher than the 35 GHz atmospheric window selected by the current mainstream armed helicopter airborne millimeter wave fire control radar. In addition, the pure phase M-type barium ferrite has a single resonance absorption characteristic, so that its effective absorption bandwidth is narrow (the effective absorption bandwidth usually refers to the frequency range of the wave absorption reflection loss RL < -10 dB), and it is difficult to meet the effective absorption and shielding of the 5G band. These parameters are difficult to meet the characteristics of "thin, wide, light and strong" that an ideal high-efficiency electromagnetic wave absorbing material should have. Therefore, reducing the natural resonance frequency and widening the effective absorption bandwidth are key problems that need to be solved to realize the wide application of M-type barium ferrite. Research shows that ion substitution is one of the effective and feasible strategies to improve its inherent defects. The natural resonance peak of M-type ferrite is proportional to the strength of the magnetocrystalline anisotropy field of the material. Non-magnetic or weakly magnetic cations can be substituted into Fe 3+ to reduce the magnetocrystalline anisotropy field and thus reduce the absorption peak frequency; through cation substitution, Fe 3+ can be converted into Fe 2+ or oxygen vacancies are introduced, thereby generating new exchange interaction, introducing new natural resonance peak, improving the concentration of dipoles in the system, optimizing the dielectric loss ability of the material, producing multi-resonance mechanism, and expanding the wave absorption spectrum.

[0004] At present, the ion substitution of M-type barium ferrite is mostly unit point substitution, that is, only Ba 2+ ions or Fe 3+ ions are substituted to improve its wave absorption performance. Non-magnetic / weakly magnetic ions or ion combinations, such as Al 3+ , Ti 4+ , Co 2+ -Ti4+ , La 3+ -Ce 3+ , etc. to substitute Fe in M-type barium ferrite 3+ ions to reduce the anisotropic field of barium ferrite, shift the natural resonance peak to low frequency, and improve the dielectric constant of barium ferrite; by changing the substitution amount of ions, such as Pb 2+ , La 3+ , Sr 2+ , Bi 3+ , etc., the magnetic properties of M-type barium ferrite can be optimized when Ba 2+ ions are substituted, so that the M-type barium ferrite can have good wave absorption performance in the required electromagnetic wave band. However, there are few studies on double-site substitution. SUMMARY

[0005] The present application aims to provide a rare earth neodymium / transition metal ion double-site substituted M-type barium ferrite wave-absorbing powder material and a preparation method thereof, which can improve the electromagnetic parameters of M-type barium ferrite and obtain a high-efficiency wave-absorbing powder material that can be applied in dual-frequency bands.

[0006] In one aspect of the present application, a rare earth neodymium / transition metal ion double-site substituted M-type barium ferrite wave-absorbing powder material is provided. According to an embodiment of the present application, the structure formula of the double-site substituted barium ferrite wave-absorbing powder material is Ba 1-x Nd x Fe 12-x A x O 19 , wherein A is Zn, Co, Ni, Ti or Zr, and in the formula, x = 0.02-0.3.

[0007] In another aspect of the present application, a preparation method of a rare earth neodymium / transition metal ion double-site substituted M-type barium ferrite wave-absorbing powder material is provided. According to an embodiment of the present application, a rare earth element neodymium and a transition metal ion A are respectively substituted for Ba 2+ and Fe 3+ sites in M-type barium ferrite to achieve simultaneous substitution of different element sites in M-type barium ferrite, thereby obtaining a rare earth element neodymium ion and transition metal ion double-site substituted M-type barium ferrite wave-absorbing powder material, wherein the transition metal ion A is Zn 2+ , Co 2+ , Ni 2+ , Ti 4+ , or Zr 4+ .

[0008] In addition, the preparation method of the rare earth neodymium / transition metal ion double-site substituted M-type barium ferrite wave-absorbing powder material according to the above-mentioned embodiments of the present application can further have the following additional technical features:

[0009] In some embodiments of the present application, the steps specifically include:

[0010] (1) Dissolve barium nitrate, neodymium nitrate, iron nitrate, transition metal source and citric acid monohydrate in a proper amount of deionized water to obtain a precursor, and stir until a transparent sol is obtained;

[0011] (2) Slowly add the transparent sol obtained in step (1) to a proper amount of ammonia water, adjust the pH value of the sol to 6.5-7.5, and after sufficient stirring, place the sol in a water bath at 80°C and continue stirring for 12-15 h to obtain a brownish wet gel;

[0012] (3) Dry the wet gel obtained in step (2) to obtain a black dry gel;

[0013] (4) Grind the dry gel obtained in step (3) and pre-calcine to fully burn the nitrate ions and ammonium ions in the system, thereby providing an effective chemical environment for obtaining high-purity M-type barium ferrite wave-absorbing powder material, and finally obtain a brick red pre-calcined sample;

[0014] (5) High-temperature calcine the pre-calcined sample obtained in step (4), cool the sample to room temperature, take out and grind, and finally obtain a rare earth element neodymium ion and transition metal ion double-site substituted M-type barium ferrite wave-absorbing powder material.

[0015] In some embodiments of the present application, in step (1), the transition metal source is zinc nitrate, cobalt nitrate, nickel nitrate, tetrabutyl titanate ethanol, or zirconium nitrate.

[0016] In some embodiments of the present application, in step (1), the molar ratio of barium nitrate, neodymium nitrate, iron nitrate, transition metal source and citric acid monohydrate is 0.7-1:0-0.3:11.7-12:0-0.3:19.

[0017] In some embodiments of the present application, in step (1), the mixing and stirring time of the precursor is 0.5-1.5 h, and the stirring speed is set to 450-650 rpm.

[0018] In some embodiments of the present application, in step (2), the stirring time after adjusting the pH of the sol is 30-60 min, the stirring speed is set to 450-650 rpm, the temperature of the water bath is 80°C, and the stirring time in the water bath is 12-15 h.

[0019] In some embodiments of the present application, in step (3), the drying temperature of the wet gel is 120-150°C, and the drying time is 24-48 h.

[0020] In some embodiments of the present application, in step (4), the pre-calcination is divided into two steps, first at 240-270℃ for 90-120 min, then heated to 400-500℃, and calcined for 1.5-3 h, with a heating rate of 3℃ / min.

[0021] In some embodiments of the present application, in step (5), the calcination temperature is 1200-1400℃, the calcination time is 3-6 h, and the heating rate is 10℃ / min.

[0022] Compared with the prior art, the present application has the following advantages:

[0023] 1) The present application uses a sol-gel synthesis method to substitute neodymium ions and transition metal ions into the M-type barium ferrite matrix, wherein the rare earth element Nd 3+ substitutes Ba 2+ ions, while the transition metal ions (Zn 2+ , Co 2+ , Ni 2+ , Ti 4+ , Zr 4+ ) substitute Fe 3+ ions, achieving simultaneous substitution of different lattice sites in M-type barium ferrite. As a light rare earth element, the substitution of neodymium can improve the grain boundary domain activity, improve the magnetic crystal anisotropy, cause lattice distortion, and ultimately enhance the domain wall resonance and natural resonance of M-type barium ferrite. This resonance loss mechanism is the main loss mechanism of M-type barium ferrite in the frequency range of 26.5-40 GHz. Substituting Fe 3+ ions with transition metal ions can reduce the magnetic crystal anisotropy of M-type barium ferrite, produce multiple natural resonance peaks, enhance the dielectric loss mechanism, and thus improve its wave absorption performance. In addition, the interaction between the rare earth element neodymium ions and the transition metal ions promotes the material to obtain a wider effective wave absorption bandwidth under the action of natural resonance and exchange coupling resonance, so that the material can have certain electromagnetic wave absorption performance in the two wave band ranges of 2-18 GHz and 26.5-40 GHz.

[0024] 2) The application can improve the wave-absorbing intensity, effective absorption bandwidth and electromagnetic wave absorption frequency band of the wave-absorbing material by adjusting the transition metal species substituted into the M-type barium ferrite, the calcination temperature and the doping content, and a more effective electromagnetic wave absorbing material can be obtained. The M-type barium ferrite with neodymium-nickel, neodymium-titanium and neodymium-zirconium double-site substitution has higher wave-absorbing performance, and the M-type barium ferrite with neodymium-zirconium double-site substitution is the best. The M-type barium ferrite with neodymium-nickel double-site substitution has higher wave-absorbing performance under the condition that x = 0.15, the matching thickness is reduced to about 2 mm, and the effective wave-absorbing bandwidth is close to 5 GHz. The M-type barium ferrite with neodymium-titanium double-site substitution has higher wave-absorbing performance under the condition that x = 0.12, the matching thickness is reduced to about 3 mm, and the effective wave-absorbing bandwidth is close to 4 GHz. The M-type barium ferrite with neodymium-zirconium double-site substitution has the optimal electromagnetic wave absorbing performance, has higher wave-absorbing performance under the condition that x = 0.125-0.2, the matching thickness is reduced to about 0.7 mm, the effective wave-absorbing bandwidth is close to 8 GHz, and the natural resonance frequency is reduced from more than 40 GHz to about 36 GHz. Through the comparative analysis of the wave-absorbing performance of the M-type barium ferrite with different transition metal ion substitution, it is shown that the wave-absorbing performance of the M-type barium ferrite is closely related to the valence state and ion radius of the doping ion.

[0025] 3) The wave-absorbing material has the characteristics of strong reflection loss. The sample doped with a certain amount has good reflection loss in the two wave band ranges of 2-18 GHz and 26.5-40 GHz. The M-type barium ferrite with neodymium-nickel double-site substitution has the best reflection loss value of-48.6 dB at a specific frequency under the condition that x = 0.15. The M-type barium ferrite with neodymium-titanium double-site substitution has the best reflection loss value of-48.2 dB at a specific frequency under the condition that x = 0.12. For the M-type barium ferrite with neodymium-zirconium double-site substitution, the best reflection loss value at a specific frequency can reach-49.2 dB when the doping amount x is 0.2.

[0026] 4) The wave-absorbing powder material in the application has simple preparation process, low raw material cost, safety, no pollution, conventional equipment and basic conditions required for large-scale production, and provides a reference for the research of cation-substituted modified M-type barium ferrite wave-absorbing material. BRIEF DESCRIPTION OF DRAWINGS

[0027] Figure 1 The wave-absorbing powder material Ba 0.9 Nd 0.1 Fe 11.9 Zn 0.1 O 19The curves of the change of the wave-absorbing performance with frequency in different frequency ranges: (a) 2-18 GHz, (b) 26.5-40 GHz;

[0028] Figure 2 The present application is a kind of neodymium zinc double site substitution M-type barium ferrite wave-absorbing powder material Ba 0.85 Nd 0.15 Fe 11.85 Zn 0.15 O 19 The curves of the change of the wave-absorbing performance with frequency in different frequency ranges: (a) 2-18 GHz, (b) 26.5-40 GHz;

[0029] Figure 3 The present application is a kind of neodymium zinc double site substitution M-type barium ferrite wave-absorbing powder material Ba 0.9 Nd 0.1 Fe 11.9 Co 0.1 O 19 The curves of the change of the wave-absorbing performance with frequency in different frequency ranges: (a) 2-18 GHz, (b) 26.5-40 GHz;

[0030] Figure 4 The present application is a kind of neodymium zinc double site substitution M-type barium ferrite wave-absorbing powder material Ba 0.85 Nd 0.15 Fe 11.85 Co 0.15 O 19 The curves of the change of the wave-absorbing performance with frequency in different frequency ranges: (a) 2-18 GHz, (b) 26.5-40 GHz;

[0031] Figure 5 The present application is a kind of neodymium zinc double site substitution M-type barium ferrite wave-absorbing powder material Ba 0.9 Nd 0.1 Fe 11.9 Ni 0.1 O 19 The curves of the change of the wave-absorbing performance with frequency in different frequency ranges: (a) 2-18 GHz, (b) 26.5-40 GHz;

[0032] Figure 6 The present application is a kind of neodymium zinc double site substitution M-type barium ferrite wave-absorbing powder material Ba 0.85 Nd 0.15 Fe 11.85 Ni 0.15 O 19The curves of the change of the wave-absorbing performance with frequency in different frequency ranges: (a) 2-18 GHz, (b) 26.5-40 GHz;

[0033] Figure 7 A neodymium-zinc double-site substituted M-type barium ferrite wave-absorbing powder material Ba 0.98 Nd 0.02 Fe 11.98 Ti 0.02 O 19 The curves of the change of the wave-absorbing performance with frequency in different frequency ranges: (a) 2-18 GHz, (b) 26.5-40 GHz;

[0034] Figure 8 A neodymium-zinc double-site substituted M-type barium ferrite wave-absorbing powder material Ba 0.92 Nd 0.08 Fe 11.92 Ti 0.08 O 19 The curves of the change of the wave-absorbing performance with frequency in different frequency ranges: (a) 2-18 GHz, (b) 26.5-40 GHz;

[0035] Figure 9 A neodymium-zinc double-site substituted M-type barium ferrite wave-absorbing powder material Ba 0.975 Nd 0.025 Fe 11.975 Zr 0.025 O 19 The curves of the change of the wave-absorbing performance with frequency in different frequency ranges: (a) 2-18 GHz, (b) 26.5-40 GHz;

[0036] Figure 10 A neodymium-zinc double-site substituted M-type barium ferrite wave-absorbing powder material Ba 0.8 Nd 0.2 Fe 11.8 Zr 0.2 O 19 The curves of the change of the wave-absorbing performance with frequency in different frequency ranges: (a) 2-18 GHz, (b) 26.5-40 GHz. DETAILED DESCRIPTION

[0037] The technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative work fall within the protection scope of the present application.

[0038] Example 1

[0039] A preparation method of a rare earth neodymium / transition metal ion double-site substituted M-type barium ferrite wave-absorbing powder material, comprising the following steps:

[0040] (1) A proper amount of deionized water is added to dissolve barium nitrate, neodymium nitrate, iron nitrate, zinc nitrate and citric acid monohydrate mixed precursors, and the molar ratio of them is 0.9:0.1:11.9:0.1:19, and the stirring is continued for 1 h until a transparent sol is obtained;

[0041] (2) A proper amount of ammonia water is slowly added to the transparent sol obtained in step (1), the pH value of the sol is adjusted to 7, and after fully stirring for 45 min, the sol is placed in a water bath at 80℃ and then continuously stirred for 15 h to obtain a brownish wet gel;

[0042] (3) The wet gel obtained in step (2) is dried at 120℃ for 36 h to obtain a fully dried black dry gel;

[0043] (4) After the dry gel obtained in step (3) is fully ground, it is heated at 250℃ for 90 min, then heated to 450℃, and calcined for 2 h at the heating rate of 3℃ / min to obtain a brick red pre-fired sample;

[0044] (5) The pre-fired sample obtained in step (4) is subjected to high-temperature calcination, the calcination temperature is 1400℃, the calcination time is 3h, the heating rate is 10℃ / min, and after the sample is cooled to room temperature, the sample is fully ground for 30 min to finally obtain a zinc double-site substituted M-type barium ferrite wave-absorbing powder material Ba 0.9 Nd 0.1 Fe 11.9 Zn 0.1 O 19 .

[0045] The wave-absorbing performance of the rare earth neodymium / zinc ion double-site substituted M-type barium ferrite wave-absorbing powder material prepared in this example is tested by using a vector network analyzer. When testing, the wave-absorbing material powder of the present application is mixed with solid paraffin at a mass ratio of 8:2 to prepare ring-shaped and block-shaped paraffin samples, and the testing is carried out in two wave band ranges of 2-18 GHz and 26.5-40 GHz, respectively.

[0046] Figure 1 is a wave-absorbing performance data graph of the neodymium and zinc double-site substituted M-type barium ferrite wave-absorbing powder material Ba 0.9 Nd 0.1 Fe 11.9 Zn 0.1 O 19 . Figure 1(a) and Figure 1 (b) are wave-absorbing agent Ba 0.9 Nd 0.1 Fe 11.9 Zn 0.1 O 19 The relationship between the wave-absorbing performance and the frequency in the frequency range of 2-18 GHz and 26.5-40 GHz. Figure 1 (a) are the wave-absorbing performance data obtained at the matching thicknesses of 4.725 and 4.875 mm, both of which have two absorption peaks, showing a double-resonance loss mechanism. As can be seen from the figure, at the matching thickness of 4.875 mm, two effective wave-absorbing bandwidths of 1.12 and 2.6 GHz can be obtained. At the matching thickness of 4.725 mm, the maximum reflection loss value of-18.42 dB is obtained at 17.08 GHz. Figure 1 (b) are the high-frequency wave-absorbing performance obtained at the matching thicknesses of 2.05 and 2.475 mm. As can be seen from the figure, at the matching thickness of 2.05 mm, an effective wave-absorbing bandwidth of 4.8 GHz can be obtained. At the matching thickness of 2.475 mm, the maximum reflection loss value of-30.64 dB is obtained at 31.33 GHz.

[0047] Example 2

[0048] A preparation method of a rare earth neodymium / transition metal ion double-site substituted M-type barium ferrite wave-absorbing powder material, comprising the following steps:

[0049] (1) A proper amount of deionized water is added to dissolve barium nitrate, neodymium nitrate, iron nitrate, zinc nitrate and citric acid monohydrate mixed precursors, and their molar ratio is 0.85:0.15:11.85:0.15:19, and stirring is continued for 1 h until a transparent sol is obtained;

[0050] (2) A proper amount of ammonia water is slowly added to the transparent sol obtained in step (1), the pH value of the sol is adjusted to 7, and after sufficient stirring for 60 min, the sol is placed in a water bath at 80℃ and then continuously stirred for 15 h to obtain a brownish wet gel;

[0051] (3) The wet gel obtained in step (2) is dried at 120℃ for 36 h to obtain a fully dried black dry gel;

[0052] (4) The dry gel obtained in step (3) is fully ground, and then a calcination program of 250℃ for 90 min, followed by heating to 450℃ and holding for 2 h at a heating rate of 3℃ / min is performed to obtain a brick red pre-fired sample;

[0053] (5) The pre-sintered sample obtained in step (4) is subjected to high-temperature calcination, the calcination temperature is 1350°C, the calcination time is 3h, the temperature rising rate is 10°C / min, the sample is cooled to room temperature, and the sample is fully ground for 30 min to obtain a neodymium and zinc ion double-substituted M-type barium ferrite wave-absorbing powder material Ba 0.85 Nd 0.15 Fe 11.85 Zn 0.15 O 19 .

[0054] The wave-absorbing performance of the rare earth neodymium / zinc ion double-substituted M-type barium ferrite wave-absorbing powder material prepared in this example is tested by using a vector network analyzer. In the test, the wave-absorbing material powder of the present application is mixed with solid paraffin at a mass ratio of 8:2 to prepare ring-shaped and block-shaped paraffin samples, and the samples are tested in two wave band ranges of 2-18 GHz and 26.5-40 GHz, respectively.

[0055] Figure 2 is a wave-absorbing performance data graph of the neodymium and zinc ion double-substituted M-type barium ferrite wave-absorbing powder material Ba 0.85 Nd 0.15 Fe 11.85 Zn 0.15 O 19 . Figure 2 (a) and Figure 2 (b) are the wave-absorbing performance curves of the wave-absorbing agent Ba 0.85 Nd 0.15 Fe 11.85 Zn 0.15 O 19 obtained in Example 2 in the frequency ranges of 2-18 GHz and 26.5-40 GHz. Figure 2 (a) is the wave-absorbing performance data obtained at a matching thickness of 4.7 and 5 mm, and there are two absorption peaks, showing a double-resonance loss mechanism. As can be seen from the graph, at a matching thickness of 4.7 mm, two effective wave-absorbing bandwidths of 1.56 and 2.48 GHz can be obtained. And at 16.6 GHz, the maximum reflection loss value of -19.45 dB is obtained. Figure 2 (b) is the high-frequency wave-absorbing performance obtained at a matching thickness of 2.1 and 2.125 mm. As can be seen from the graph, at a matching thickness of 2.1 mm, an effective wave-absorbing bandwidth of 5.1 GHz can be obtained. And at a matching thickness of 2.125 mm, the maximum reflection loss value of -56.95 dB is obtained at 36.35 GHz.

[0056] Example 3

[0057] A preparation method of a rare earth neodymium / transition metal ion double-site substituted M-type barium ferrite wave-absorbing powder material, comprising the following steps:

[0058] (1) A proper amount of deionized water is added to dissolve barium nitrate, neodymium nitrate, iron nitrate, cobalt nitrate and citric acid monohydrate mixed precursors, and the molar ratio of the precursors is 0.9:0.1:11.9:0.1:19, and the stirring is continued for 1 h until a transparent sol is obtained;

[0059] (2) A proper amount of ammonia water is slowly added to the transparent sol obtained in step (1), the pH value of the sol is adjusted to 7, and after sufficient stirring for 45 min, the sol is placed in a water bath at 80℃ and then continuously stirred for 15 h to obtain a brownish wet gel;

[0060] (3) The wet gel obtained in step (2) is dried at 120℃ for 36 h to obtain a fully dried black dry gel;

[0061] (4) After the dry gel obtained in step (3) is fully ground, a calcination procedure is performed at 250℃ for 90 min, then the temperature is increased to 450℃ and the sample is calcined for 2 h at the temperature, and the heating rate is 3℃ / min, to obtain a brick red pre-fired sample;

[0062] (5) The pre-fired sample obtained in step (4) is subjected to high-temperature calcination, the calcination temperature is 1400℃, the calcination time is 3 h, and the heating rate is 10℃ / min, and after the sample is cooled to room temperature, the sample is fully ground for 30 min, and finally a neodymium and cobalt double-site substituted M-type barium ferrite wave-absorbing powder material Ba 0.9 Nd 0.1 Fe 11.9 Co 0.1 O 19 .

[0063] The wave-absorbing performance of the rare earth neodymium / cobalt ion double-site substituted M-type barium ferrite wave-absorbing powder material prepared in the example is tested by using a vector network analyzer. When testing, the wave-absorbing material powder of the application is mixed with solid paraffin at a mass ratio of 8:2 to prepare ring-shaped and block-shaped paraffin samples, and the testing is performed in two wave band ranges of 2-18 GHz and 26.5-40 GHz, respectively.

[0064] Figure 3 is a wave-absorbing performance data graph of the neodymium and cobalt double-site substituted M-type barium ferrite wave-absorbing powder material Ba 0.9 Nd 0.1 Fe 11.9 Co 0.1 O 19 . Figure 3 (a) and Figure 3 (b) are respectively wave-absorbing agents Ba 0.9 Nd0.1 Fe 11.9 Co 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 3 (a) shows the absorption performance data obtained at matching thicknesses of 4.7 and 5 mm. Both data exhibit two absorption peaks, demonstrating a double resonant loss mechanism. As shown in the figure, an effective absorption bandwidth of 1.88 GHz can be obtained at a matching thickness of 4.875 mm. However, at a matching thickness of 5 mm, the maximum reflection loss value of -23.28 dB is obtained at 16.04 GHz. Figure 3 (b) shows the high-frequency absorption performance obtained with matching thicknesses of 3.55 mm and 3.575 mm. As can be seen from the figure, an effective absorption bandwidth of 2.6 GHz can be obtained with a matching thickness of 3.55 mm. However, with a matching thickness of 3.575 mm, the maximum reflection loss of -26.71 dB is obtained at 38.35 GHz.

[0065] Example 4

[0066] A method for preparing a rare-earth neodymium / transition metal ion dual-substituted M-type barium ferrite microwave absorbing powder material includes the following steps:

[0067] (1) Add an appropriate amount of deionized water to dissolve the mixed precursors of barium nitrate, neodymium nitrate, ferric nitrate, cobalt nitrate and citric acid monohydrate, with a molar ratio of 0.85:0.15:11.85:0.15:19. Stir continuously for 1 h until a transparent sol is obtained.

[0068] (2) Slowly add an appropriate amount of ammonia to the transparent sol obtained in step (1), adjust the pH of the sol to 7, stir thoroughly for 45 min, place the sol in a water bath at 80°C and continue stirring for 15 h to obtain a brown wet gel.

[0069] (3) The wet gel obtained in step (2) is dried at 120°C for 36 h to obtain a fully dried black gel;

[0070] (4) After grinding the dry gel obtained in step (3), keep it at 250℃ for 90 min, then raise the temperature to 450℃ and keep it at calcined for 2 h with a heating rate of 3℃ / min to obtain a brick red pre-calcined sample.

[0071] (5) The pre-sintered sample obtained in step (4) is subjected to high-temperature calcination, the calcination temperature is 1350°C, the calcination time is 3h, the temperature rising rate is 10°C / min, the sample is cooled to room temperature, and the sample is fully ground for 30 min to obtain the neodymium and cobalt double-site substituted M-type barium ferrite wave-absorbing powder material Ba 0.85 Nd 0.15 Fe 11.85 Co 0.15 O 19 .

[0072] The wave-absorbing performance of the rare earth neodymium / cobalt ion double-site substituted M-type barium ferrite wave-absorbing powder material prepared in the embodiment is tested by using a vector network analyzer. In the test, the wave-absorbing material powder of the present application is mixed with solid paraffin at a mass ratio of 8:2 to prepare ring-shaped and block-shaped paraffin samples, and the test is performed in two wave band ranges of 2-18 GHz and 26.5-40 GHz, respectively.

[0073] Figure 4 is the wave-absorbing performance data graph of the neodymium and cobalt double-site substituted M-type barium ferrite wave-absorbing powder material Ba 0.85 Nd 0.15 Fe 11.85 Co 0.15 O 19 . Figure 4 (a) and Figure 4 (b) are the wave-absorbing performance curves of the wave-absorbing agent Ba 0.85 Nd 0.15 Fe 11.85 Co 0.15 O 19 obtained in Example 4 in the frequency ranges of 2-18 GHz and 26.5-40 GHz. Figure 4 (a) is the wave-absorbing performance data obtained at a matching thickness of 4.35 and 4.575 mm, both of which have two absorption peaks, showing a double-resonance loss mechanism. As can be seen from the graph, at a matching thickness of 4.575 mm, two effective wave-absorbing bandwidths of 1.6 and 2.32 GHz can be obtained. At a matching thickness of 4.575 mm, the maximum reflection loss value of 17.6 GHz is -25.38 dB. Figure 4 (b) is the high-frequency wave-absorbing performance obtained at a matching thickness of 2.15 and 2.275 mm. As can be seen from the graph, at a matching thickness of 2.15 mm, an effective wave-absorbing bandwidth of 4 GHz can be obtained. At a matching thickness of 2.275 mm, the maximum reflection loss value of 36.02 GHz is -20.9 dB.

[0074] Example 5

[0075] A preparation method of a rare earth neodymium / transition metal ion double-site substituted M-type barium ferrite wave-absorbing powder material, comprising the following steps:

[0076] (1) A proper amount of deionized water is added to dissolve barium nitrate, neodymium nitrate, iron nitrate, nickel nitrate and citric acid monohydrate mixed precursors, and the molar ratio of the precursors is 0.9:0.1:11.9:0.1:19, and the stirring is continued for 1 h until a transparent sol is obtained;

[0077] (2) A proper amount of ammonia water is slowly added to the transparent sol obtained in step (1), the pH value of the sol is adjusted to 7, and after sufficient stirring for 45 min, the sol is placed in a water bath at 80℃ and then continuously stirred for 15 h to obtain a brownish wet gel;

[0078] (3) The wet gel obtained in step (2) is dried at 120℃ for 36 h to obtain a fully dried black dry gel;

[0079] (4) After the dry gel obtained in step (3) is fully ground, a calcination procedure is carried out at 250℃ for 90 min, then the temperature is raised to 450℃ and the sample is calcined for 2 h at the temperature, and the heating rate is 3℃ / min, to obtain a brick red pre-fired sample;

[0080] (5) The pre-fired sample obtained in step (4) is subjected to high-temperature calcination, the calcination temperature is 1400℃, the calcination time is 3 h, and the heating rate is 10℃ / min, and after the sample is cooled to room temperature, the sample is fully ground for 30 min, and finally a neodymium and nickel double-site substituted M-type barium ferrite wave-absorbing powder material Ba 0.9 Nd 0.1 Fe 11.9 Ni 0.1 O 19 .

[0081] The wave-absorbing performance of the rare earth neodymium / nickel ion double-site substituted M-type barium ferrite wave-absorbing powder material prepared in the example is tested by using a vector network analyzer. When testing, the wave-absorbing material powder of the application is mixed with solid paraffin at a mass ratio of 8:2 to prepare ring-shaped and block-shaped paraffin samples, and the testing is carried out in two wave band ranges of 2-18 GHz and 26.5-40 GHz, respectively.

[0082] Figure 5 is a wave-absorbing performance data graph of the neodymium and nickel double-site substituted M-type barium ferrite wave-absorbing powder material Ba 0.9 Nd 0.1 Fe 11.9 Ni 0.1 O 19 . Figure 5 (a) and Figure 5 (b) are respectively wave-absorbing agents Ba 0.9 Nd0.1 Fe 11.9 Ni 0.1 O 19 The relationship curve between the wave absorption performance and the frequency in the frequency range of 2-18 GHz and 26.5-40 GHz. Figure 5 (a) The wave absorption performance data obtained at the matching thicknesses of 4.425 and 4.675 mm, both of which have two absorption peaks, showing a double-resonance loss mechanism. As can be seen from the figure, at the matching thickness of 4.675 mm, two effective wave absorption bandwidths of 1.2 and 2.44 GHz can be obtained. At the matching thickness of 4.425 mm, the maximum reflection loss value of 17.6 GHz is-18.43 dB. Figure 5 (b) The high-frequency wave absorption performance obtained at the matching thicknesses of 2.125 and 2.9 mm. As can be seen from the figure, at the matching thickness of 2.125 mm, an effective wave absorption bandwidth of 4.3 GHz can be obtained, and the best reflection loss value of 37.6 GHz is-43.32 dB. At the matching thickness of 2.9 mm, an effective wave absorption bandwidth of 3.41 GHz is obtained, and the strongest reflection loss value of 28.05 GHz is-38.28 dB.

[0083] Example 6

[0084] A preparation method of a rare earth neodymium / transition metal ion double-site substituted M-type barium ferrite wave absorption powder material, comprising the following steps:

[0085] (1) A proper amount of deionized water is added to dissolve barium nitrate, neodymium nitrate, iron nitrate, nickel nitrate and citric acid monohydrate mixed precursors, and their molar ratio is 0.85:0.15:11.85:0.15:19, and stirring is continued for 1 h until a transparent sol is obtained;

[0086] (2) A proper amount of ammonia water is slowly added to the transparent sol obtained in step (1), the pH value of the sol is adjusted to 7, and after fully stirring for 45 min, the sol is placed in a water bath at 80℃ and then continuously stirred for 15 h to obtain a brownish wet gel;

[0087] (3) The wet gel obtained in step (2) is dried at 120℃ for 36 h to obtain a fully dried black dry gel;

[0088] (4) The dry gel obtained in step (3) is fully ground, and then a calcination program of 250℃ for 90 min, followed by heating to 450℃ and holding for 2 h at a heating rate of 3℃ / min is carried out to obtain a brick red pre-fired sample;

[0089] (5) The pre-sintered sample obtained in step (4) is subjected to high-temperature calcination, the calcination temperature is 1350°C, the calcination time is 3h, the temperature rising rate is 10°C / min, the sample is cooled to room temperature, the sample is fully ground for 30 min, and finally the neodymium and nickel double-site substituted M-type barium ferrite wave-absorbing powder material Ba 0.85 Nd 0.15 Fe 11.85 Ni 0.15 O 19 .

[0090] The wave-absorbing performance of the rare earth neodymium / nickel ion double-site substituted M-type barium ferrite wave-absorbing powder material prepared in this example is tested by using a vector network analyzer. When testing, the wave-absorbing material powder of the application is mixed with solid paraffin at a mass ratio of 8:2 to prepare ring-shaped and block-shaped paraffin samples, and the testing is performed in two wave band ranges of 2-18 GHz and 26.5-40 GHz, respectively.

[0091] Figure 6 is the wave-absorbing performance data graph of the neodymium and nickel double-site substituted M-type barium ferrite wave-absorbing powder material Ba 0.85 Nd 0.15 Fe 11.85 Ni 0.15 O 19 . Figure 6 (a) and Figure 6 (b) are the wave-absorbing performance curves of the wave-absorbing agent Ba 0.85 Nd 0.15 Fe 11.85 Ni 0.15 O 19 obtained in Example 6 in the frequency ranges of 2-18 GHz and 26.5-40 GHz. Figure 6 (a) is the wave-absorbing performance data obtained at matching thicknesses of 4.275 and 4.525 mm, both of which have two absorption peaks, showing a double-resonance loss mechanism. As can be seen from the graph, at a matching thickness of 4.525 mm, two effective wave-absorbing bandwidths of 1.96 and 2.4 GHz can be obtained. At a matching thickness of 4.275 mm, the maximum reflection loss value of 5.6 GHz is -56.28 dB. Figure 6 (b) is the high-frequency wave-absorbing performance obtained at matching thicknesses of 1.975 and 2.1 mm. As can be seen from the graph, at a matching thickness of 2.1 mm, an effective wave-absorbing bandwidth of 3.85 GHz can be obtained. At a matching thickness of 1.975 mm, the maximum reflection loss value of 39.36 GHz is -39.7 dB.

[0092] Example 7

[0093] A preparation method of a rare earth neodymium / transition metal ion double-site substituted M-type barium ferrite wave-absorbing powder material, comprising the following steps:

[0094] (1) A proper amount of deionized water is added to dissolve barium nitrate, neodymium nitrate, iron nitrate, tetrabutyl titanate (dissolved in anhydrous ethanol) and citric acid monohydrate mixed precursors, and the molar ratio of the above-mentioned substances is 0.98:0.02:11.98:0.02:19, and the stirring is continued for 1.5 h until a transparent sol is obtained;

[0095] (2) A proper amount of ammonia water is slowly added to the transparent sol obtained in step (1), the pH value of the sol is adjusted to 7, and after the sol is fully stirred for 45 min, the sol is placed in a water bath at 80℃ and then continuously stirred for 15 h to obtain a brownish wet gel;

[0096] (3) The wet gel obtained in step (2) is dried at 120℃ for 36 h to obtain a fully dried black dry gel;

[0097] (4) After the dry gel obtained in step (3) is fully ground, a calcination procedure is carried out, in which the temperature is kept at 250℃ for 90 min, then the temperature is increased to 450℃ and kept for 2 h, and the heating rate is 3℃ / min, to obtain a brick red pre-fired sample;

[0098] (5) The pre-fired sample obtained in step (4) is subjected to high-temperature calcination, the calcination temperature is 1400℃, the calcination time is 3 h, the heating rate is 10℃ / min, and after the sample is cooled to room temperature, the sample is fully ground for 30 min, and finally a neodymium and titanium double-site substituted M-type barium ferrite wave-absorbing powder material Ba 0.98 Nd 0.02 Fe 11.98 Ti 0.02 O 19 is obtained.

[0099] The wave-absorbing performance of the rare earth neodymium / titanium ion double-site substituted M-type barium ferrite wave-absorbing powder material prepared in the example is tested by using a vector network analyzer. When testing, the wave-absorbing material powder of the application is mixed with solid paraffin at a mass ratio of 8:2 to prepare ring-shaped and block-shaped paraffin samples, and the testing is carried out in two wave band ranges of 2-18 GHz and 26.5-40 GHz, respectively.

[0100] Figure 7 is the wave-absorbing performance data graph of the neodymium and titanium double-site substituted M-type barium ferrite wave-absorbing powder material Ba 0.98 Nd 0.02 Fe 11.98 Ti 0.02 O 19 . Figure 7 (a) and Figure 7(b) are wave-absorbing agents Ba 0.98 Nd 0.02 Fe 11.98 Ti 0.02 O 19 The relationship between the wave-absorbing performance and the frequency in the frequency range of 2-18 GHz and 26.5-40 GHz. Figure 7 (a) are the wave-absorbing performance data obtained at the matching thicknesses of 4.5 and 4.925 mm, both of which have two absorption peaks, showing a double-resonance loss mechanism. As can be seen from the figure, at the matching thickness of 4.5 mm, two effective wave-absorbing bandwidths of 1.74 and 2.2 GHz can be obtained. At the matching thickness of 4.925 mm, the maximum reflection loss value of-30.38 dB is obtained at 4.56 GHz. Figure 7 (b) are the high-frequency wave-absorbing performance obtained at the matching thicknesses of 1.9, 1.925 and 2.8 mm. As can be seen from the figure, at the matching thicknesses of 1.925 and 2.8 mm, good effective wave-absorbing bandwidths of 3.61 and 3.34 GHz can be obtained, respectively. At the matching thickness of 1.925 mm, the strongest reflection loss value of-49 dB is obtained at 38.58 GHz.

[0101] Example 8

[0102] A preparation method of a rare earth neodymium / transition metal ion double-site substituted M-type barium ferrite wave-absorbing powder material, comprising the following steps:

[0103] (1) A proper amount of deionized water is added to dissolve barium nitrate, neodymium nitrate, iron nitrate, tetrabutyl titanate (which has been dissolved in anhydrous ethanol) and citric acid monohydrate mixed precursors, and their molar ratio is 0.85:0.15:11.85:0.15:19. Stir for 0.5-1.5 h until a transparent sol is obtained;

[0104] (2) A proper amount of ammonia water is slowly added to the transparent sol obtained in step (1) to adjust the pH value of the sol to 7. After stirring for 45 min, the sol is placed in a water bath at 80°C and then continuously stirred for 15 h to obtain a brownish wet gel;

[0105] (3) The wet gel obtained in step (2) is dried at 120°C for 36 h to obtain a fully dried black dry gel;

[0106] (4) The dry gel obtained in step (3) is fully ground, and then a calcination program of 250°C for 90 min, followed by heating to 450°C and holding for 2 h at a heating rate of 3°C / min is performed to obtain a brick red pre-fired sample;

[0107] (5) The pre-sintered sample obtained in step (4) is subjected to high-temperature calcination, the calcination temperature is 1350°C, the calcination time is 3h, the temperature rising rate is 10°C / min, the sample is cooled to room temperature, and the sample is fully ground for 30 min to obtain a neodymium and titanium double-site substituted M-type barium ferrite wave-absorbing powder material Ba 0.92 Nd 0.08 Fe 11.92 Ti 0.08 O 19 .

[0108] The wave-absorbing performance of the rare earth neodymium / titanium ion double-site substituted M-type barium ferrite wave-absorbing powder material prepared in this example is tested by using a vector network analyzer. In the test, the wave-absorbing material powder of the application is mixed with solid paraffin at a mass ratio of 8:2 to prepare ring-shaped and block-shaped paraffin samples, and the test is performed in two wave band ranges of 2-18 GHz and 26.5-40 GHz, respectively.

[0109] Figure 8 is a wave-absorbing performance data graph of the neodymium and titanium double-site substituted M-type barium ferrite wave-absorbing powder material Ba 0.92 Nd 0.08 Fe 11.92 Ti 0.08 O 19 . Figure 8 (a) and Figure 8 (b) are the wave-absorbing performance curves of the wave-absorbing agent Ba 0.92 Nd 0.08 Fe 11.92 Ti 0.08 O 19 obtained in Example 8 in the frequency ranges of 2-18 GHz and 26.5-40 GHz. Figure 8 (a) is the wave-absorbing performance data obtained at matching thicknesses of 3.525 and 4.35 mm. As can be seen from the graph, at a matching thickness of 4.35 mm, there are two absorption peaks, showing a double-resonance loss mechanism, and two effective wave-absorbing bandwidths are obtained, which are 1.96 and 2.12 GHz, respectively. At a matching thickness of 3.525 mm, the maximum reflection loss value of 6.64 GHz is-56.36 dB. Figure 8 (b) is the high-frequency wave-absorbing performance obtained at matching thicknesses of 1.95, 2.075 and 2.925 mm. As can be seen from the graph, at matching thicknesses of 2.075 and 2.925 mm, good effective wave-absorbing bandwidths of 3.48 and 3.38 GHz, respectively, can be obtained. At a matching thickness of 1.95 mm, the strongest reflection loss value of 39.56 GHz is-41.37 dB.

[0110] Example 9

[0111] A preparation method of a rare earth neodymium / transition metal ion double-site substituted M-type barium ferrite wave-absorbing powder material, comprising the following steps:

[0112] (1) A proper amount of deionized water is added to dissolve barium nitrate, neodymium nitrate, iron nitrate, zirconium nitrate and citric acid monohydrate mixed precursors, and the molar ratio of the precursors is 0.975:0.025:11.975:0.025:19, and the stirring is continued for 1 h until a transparent sol is obtained;

[0113] (2) A proper amount of ammonia water is slowly added to the transparent sol obtained in step (1), the pH value of the sol is adjusted to 7, and after sufficient stirring for 45 min, the sol is placed in a water bath at 80℃ and then continuously stirred for 15 h to obtain a brownish wet gel;

[0114] (3) The wet gel obtained in step (2) is dried at 120℃ for 36 h to obtain a fully dried black dry gel;

[0115] (4) After the dry gel obtained in step (3) is fully ground, a calcination procedure is carried out at 250℃ for 90 min, then the temperature is raised to 450℃ and the sample is calcined for 2 h at the temperature, and the heating rate is 3℃ / min, to obtain a brick red pre-fired sample;

[0116] (5) The pre-fired sample obtained in step (4) is subjected to high-temperature calcination, the calcination temperature is 1350℃, the calcination time is 3 h, and the heating rate is 10℃ / min, and after the sample is cooled to room temperature, the sample is fully ground for 30 min, and finally a neodymium and zirconium double-site substituted M-type barium ferrite wave-absorbing powder material Ba 0.975 Nd 0.025 Fe 11.975 Zr 0.025 O 19 .

[0117] The wave-absorbing performance of the rare earth neodymium / zirconium ion double-site substituted M-type barium ferrite wave-absorbing powder material prepared in this example is tested by using a vector network analyzer. When testing, the wave-absorbing material powder of the present application is mixed with solid paraffin at a mass ratio of 8:2 to prepare ring-shaped and block-shaped paraffin samples, and the testing is carried out in two wave band ranges of 2-18 GHz and 26.5-40 GHz, respectively.

[0118] Figure 9 is a wave-absorbing performance data graph of the neodymium and zirconium double-site substituted M-type barium ferrite wave-absorbing powder material Ba 0.975 Nd 0.025 Fe 11.975 Zr 0.025 O 19 . Figure 9 (a) and Figure 9(b) Absorber Ba obtained from Example 7 0.975 Nd 0.025 Zr 11.975 Ti 0.02 5O 19 The relationship between the microwave absorbing performance and the frequency in the frequency range of 2-18 GHz and 26.5-40 GHz. Figure 9 (a) Absorbing performance data obtained at the matching thickness of 1.3 and 1.5 mm. As can be seen from the figure, at the matching thickness of 1.5 mm, a better effective absorbing bandwidth of 5.16 GHz is obtained. At the matching thickness of 1.3 mm, the maximum reflection loss value of -22 dB is obtained at 17.4 GHz. Figure 9 (b) High-frequency absorbing performance obtained at the matching thickness of 0.75, 0.825 and 0.925 mm. As can be seen from the figure, at the matching thickness of 0.75 and 0.825 mm, a better effective absorbing bandwidth of 9.82 and 10.29 GHz can be obtained respectively. At the matching thickness of 0.925 mm, the strongest reflection loss value of -26.1 dB is obtained at 27.28 GHz.

[0119] Example 10

[0120] A preparation method of a rare earth neodymium / transition metal ion double-site substituted M-type barium ferrite microwave absorbing powder material, comprising the following steps:

[0121] (1) A certain amount of deionized water is added to dissolve barium nitrate, neodymium nitrate, iron nitrate, zirconium nitrate and citric acid monohydrate mixed precursors, and their molar ratio is 0.8:0.2:11.8:0.2:19. Stir continuously for 1 h until a transparent sol is obtained;

[0122] (2) A certain amount of ammonia water is slowly added to the transparent sol obtained in step (1) to adjust the pH value of the sol to 7. After sufficient stirring for 45 min, the sol is placed in a water bath at 80°C and then continuously stirred for 15 h to obtain a brownish wet gel;

[0123] (3) The wet gel obtained in step (2) is dried at 120°C for 36 h to obtain a fully dried black dry gel;

[0124] (4) The dry gel obtained in step (3) is fully ground, and then calcined according to the calcination procedure of 250°C for 90 min, then heated to 450°C and kept for 2 h, with a heating rate of 3°C / min, to obtain a brick red pre-fired sample;

[0125] (5) The pre-sintered sample obtained in step (4) is subjected to high-temperature calcination, the calcination temperature is 1400°C, the calcination time is 3h, the temperature rising rate is 10°C / min, the sample is cooled to room temperature, the sample is fully ground for 30 min, and finally the neodymium and zirconium double-site substituted M-type barium ferrite wave-absorbing powder material Ba 0.8 Nd 0.2 Fe 11.8 Zr 0.2 O 19 .

[0126] The wave-absorbing performance of the rare earth neodymium / zirconium ion double-site substituted M-type barium ferrite wave-absorbing powder material prepared in the embodiment is tested by using a vector network analyzer. When testing, the wave-absorbing material powder of the present application is mixed with solid paraffin at a mass ratio of 8:2 to prepare ring-shaped and block-shaped paraffin samples, and the testing is performed in two wave band ranges of 2-18 GHz and 26.5-40 GHz, respectively.

[0127] Figure 10 is a wave-absorbing performance data graph of the neodymium and zirconium double-site substituted M-type barium ferrite wave-absorbing powder material Ba 0.8 Nd 0.2 Fe 11.8 Zr 0.2 O 19 . Figure 10 (a) and Figure 10 (b) are respectively the wave-absorbing performance curves of the wave-absorbing agent Ba 0.8 Nd 0.2 Fe 11.8 Zr 0.2 O 19 obtained in Example 10 in the frequency ranges of 2-18 GHz and 26.5-40 GHz. Figure 10 (a) is the wave-absorbing performance data obtained at matching thicknesses of 1.525 and 3.975 mm. As can be seen from the graph, at the matching thickness of 1.525 mm, a wider effective wave-absorbing bandwidth of 4.36 GHz is obtained. At the matching thickness of 3.975 mm, the maximum reflection loss value of -29.17 dB is obtained at 5.2 GHz. Figure 10 (b) is the high-frequency wave-absorbing performance obtained at matching thicknesses of 0.575 and 0.725 mm. As can be seen from the graph, at the matching thickness of 0.725 mm, a better effective wave-absorbing bandwidth of 8.17 GHz can be obtained. At the matching thickness of 0.575 mm, the strongest reflection loss value of -49.15 dB is obtained at 36.29 GHz.

[0128] The above examples are more typical embodiments of the present application, and are not any limitation on the present application, for example, water bath temperature, wet gel drying temperature, pre-calcination temperature, calcination temperature, calcination time, etc. can be further adjusted. Therefore, according to the general idea of the present application, the process parameters described by the skilled in the art are adjusted and modified, as long as it does not deviate from the concept of the application or beyond the scope defined by the present claims, it shall belong to the protection scope of the present application.

[0129] The above content is only an example and description of the structure of the present application, and the skilled in the art can make various modifications or supplements or replace with similar ways, as long as it does not deviate from the structure of the present application or beyond the scope defined by the present claims, it shall belong to the protection scope of the present application.

Claims

1. A method for preparing a rare-earth neodymium / transition metal ion dual-substituted M-type barium ferrite microwave absorbing powder material, characterized in that, Specifically, the following steps are included: (1) Add an appropriate amount of deionized water to dissolve barium nitrate, neodymium nitrate, ferric nitrate, transition metal source and citric acid monohydrate to obtain a precursor, and stir until a transparent sol is obtained; (2) Slowly add an appropriate amount of ammonia water to the transparent sol obtained in step (1), adjust the pH value of the sol to 6.5-7.5, stir thoroughly, place the sol in a water bath at 80°C and continue stirring for 12-15 h to obtain a brown wet gel. (3) Dry the wet gel obtained in step (2) thoroughly to obtain a black dry gel; (4) The dry gel obtained in step (3) is thoroughly ground and pre-calcined to obtain a brick-red pre-calcined sample. The pre-calcination is divided into two steps: first, the sample is kept at 240-270℃ for 90-120 min, then the temperature is raised to 400-500℃ and kept at calcined for 1.5-3 h. The heating rate is 3℃ / min. (5) The pre-calcined sample obtained in step (4) is subjected to high-temperature calcination. After the sample is cooled to room temperature, it is taken out and ground to finally obtain a rare earth element neodymium ion and transition metal ion double-substituted M-type barium ferrite microwave absorbing powder material. The structural formula of the double-substituted barium ferrite microwave absorbing powder material is Ba 1-x Nd x Fe 12-x A x O 19 Where A is Ni, Ti or Zr, and x = 0.02-0.

3.

2. The preparation method of a rare earth neodymium / transition metal ion dual-substituted M-type barium ferrite microwave absorbing powder material according to claim 1, characterized in that: In step (1), the transition metal source is nickel nitrate, tetrabutyl titanate ethanol, or zirconium nitrate.

3. The preparation method of a rare earth neodymium / transition metal ion dual-substituted M-type barium ferrite microwave absorbing powder material according to claim 1, characterized in that: In step (1), the precursor mixing and stirring time is 0.5-1.5 h, and the stirring speed is 450-650 rpm.

4. The preparation method of a rare earth neodymium / transition metal ion dual-substituted M-type barium ferrite microwave absorbing powder material according to claim 1, characterized in that: In step (2), the stirring time after adjusting the pH of the sol is 30-60 min, and the stirring speed is 450-650 rpm.

5. The preparation method of a rare earth neodymium / transition metal ion dual-substituted M-type barium ferrite microwave absorbing powder material according to claim 1, characterized in that: In step (3), the drying temperature of the wet gel is 120-150℃ and the drying time is 24-48 h.

6. The preparation method of a rare earth neodymium / transition metal ion dual-substituted M-type barium ferrite microwave absorbing powder material according to claim 1, characterized in that: In step (5), the calcination temperature is 1200-1400℃, the calcination time is 3-6 h, and the heating rate is 10℃ / min.

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