Pr and Dy co-doped M-type hexaferrite material, preparation method and application thereof

Abstract

This invention provides a praseodymium-dysprosium co-doped M-type hexagonal ferrite material, its preparation method, and its application. The chemical formula of the praseodymium-dysprosium co-doped M-type hexagonal ferrite material is A. y Fe 12‑2x Pr x Dy x O 19 Where A is strontium and / or barium, 0.05≤x≤1, 0.9≤y≤1.4. This invention incorporates praseodymium and dysprosium into M-type hexagonal ferrite, reducing grain size and forming polyhedral aggregates. Simultaneously, praseodymium-dysprosium co-doping can form various impurity phases, creating interfaces between the impurity phases and the main phase, effectively promoting interfacial polarization. Furthermore, Pr... 3+ To Pr 4+ The conversion favors oxygen vacancies and Fe 2+ The formation of praseodymium-dysprosium co-doped M-type hexagonal ferrite material improves the dielectric properties and microwave absorption properties of the material. Furthermore, the praseodymium-dysprosium co-doped M-type hexagonal ferrite material provided by this invention has advantages such as tunable absorption frequency band, high absorption intensity, and high operating temperature, exhibiting stable absorption performance and can be used as a base material for other composite materials.

Description

Technical Field

[0001] This invention belongs to the field of electromagnetic wave absorbing materials, specifically relating to a praseodymium-dysprosium co-doped M-type hexagonal ferrite material, its preparation method, and its application. Background Technology

[0002] In recent years, M-type hexagonal ferrite (MFe) has been widely used. 12 O 19 M-type hexagonal ferrites (Sr, Ba, Pb) have attracted widespread attention due to their relatively low price, high saturation magnetization (MS), high coercivity, high resistivity, corrosion resistance, and excellent chemical stability, and have been widely used in microwave devices, magneto-optics, magnetic recording media, and high-frequency devices in the form of permanent magnets. M-type hexagonal ferrites are widely used as microwave absorbing materials (EMWs), capable of absorbing microwaves and converting them into heat or other energy. According to physical principles, electromagnetic wave absorption typically includes magnetic loss and dielectric loss types, although researchers have synthesized various microwave absorbing materials over the years. However, ferrites, especially spinel and hexagonal ferrites, as traditional magnetic loss type microwave absorbing materials, remain the preferred choice for electromagnetic wave absorbing materials due to their strong magnetic loss, ease of synthesis, and low cost.

[0003] Ion doping is an important way to improve the microwave absorption performance of M-type ferrites. Sharbati et al. synthesized nanocrystalline SrFe. 12-2x Mg x Zr x O 19 Furthermore, by controlling the levels of substituted Zr and Mg elements in the strontium ferrite (x = 0.5, 1.0, and 1.5), satisfactory reflection loss was obtained in the 8 GHz range. Sriramulu et al. investigated Sr(Zr-Mn). x Fe 12-2x O 19 The electromagnetic properties of the six-ferrite material were studied, and it was observed that the minimum reflection loss was -27.68 dB in the 10.14-10.64 GHz frequency band when x = 0.6. However, the absorption intensity and bandwidth of the above-mentioned ferrites need to be improved. Chinese patent CN202211423723.3 discloses a cerium-doped barium ferrite absorbing material and its preparation method. The molecular formula of the cerium-doped barium ferrite material is BaCe. 0.2 Fe 11.8 O 19The material has a grain size of 2.43 μm and is prepared using the sol-gel method. With a matching thickness of 2.3 mm, the reflection loss at 10.35 GHz is -59.5 dB, and the effective bandwidth is 9.72 GHz. Chinese Invention Patent 202211607238.1 provides a Ku-band Zr-Co co-doped M-type barium ferrite absorbing material, its preparation method, and its application. The chemical formula is BaFe. 12-2x (CoZr) x O19, where x is 0.3-0.5. However, the above patent has drawbacks such as stringent requirements on ingredient ratios and preparation processes.

[0004] Therefore, there is an urgent need to develop a new M-type hexagonal ferrite material to solve the above problems. Summary of the Invention

[0005] To address the shortcomings of existing technologies, the present invention aims to provide a praseodymium-dysprosium co-doped M-type hexagonal ferrite material, its preparation method, and its applications. This invention incorporates praseodymium and dysprosium into M-type hexagonal ferrite, utilizing the variable valence and large ionic radius of praseodymium, combined with Fe deficiency... 3+ Hefu Sr 2+ Or Ba 2+ The environment makes Pr 4+ This process reduces grain size and forms polyhedral aggregates. Simultaneously, the co-doping of praseodymium and dysprosium can form various impurity phases, which interact with the main phase, effectively promoting interfacial polarization. Furthermore, Pr... 3+ To Pr 4+ The conversion favors oxygen vacancies and Fe 2+ The formation of this material significantly improves its dielectric properties and enhances its microwave absorption performance. Furthermore, the praseodymium-dysprosium co-doped M-type hexagonal ferrite material provided by this invention has advantages such as tunable absorption frequency band, high absorption intensity, and high operating temperature, exhibiting stable absorption performance and making it suitable as a base material for other composite materials.

[0006] To achieve this objective, the present invention adopts the following technical solution:

[0007] In a first aspect, the present invention provides a praseodymium-dysprosium co-doped M-type hexagonal ferrite material, wherein the chemical formula of the praseodymium-dysprosium co-doped M-type hexagonal ferrite material is A. y Fe 12-2x Pr x Dy x O 19 Where A is strontium and / or barium, 0.05≤x≤1, 0.9≤y≤1.4.

[0008] This invention incorporates praseodymium and dysprosium into M-type hexagonal ferrite, utilizing the variable valence and large ionic radius of praseodymium, combined with Fe deficiency. 3+ Hefu Sr2+ Or Ba 2+ The environment makes Pr 4+ This process reduces grain size and forms polyhedral aggregates. Simultaneously, the co-doping of praseodymium and dysprosium can form various impurity phases, which interact with the main phase, effectively promoting interfacial polarization. Furthermore, Pr... 3+ To Pr 4+ The conversion favors oxygen vacancies and Fe 2+ The formation of this material significantly improves its dielectric properties and enhances its microwave absorption performance. Furthermore, the praseodymium-dysprosium co-doped M-type hexagonal ferrite material provided by this invention has advantages such as tunable absorption frequency band, high absorption intensity, and high operating temperature, exhibiting stable absorption performance and making it suitable as a base material for other composite materials.

[0009] In this invention, 0.05 ≤ x ≤ 1, for example, it can be 0.05, 0.1, 0.2, 0.3, 0.4, 0.8, or 1.0, etc. However, it is not limited to the listed values, and other unlisted values ​​within the range are also applicable.

[0010] In this invention, if the value of x is too small, the lattice distortion caused by rare earth doping is not obvious, and the dielectric loss and magnetic loss are not significantly different compared with strontium ferrite, thus affecting the microwave absorption effect. If the value of x is too large, too many impurities that are detrimental to the microwave absorption effect are generated, the main phase that is beneficial to the microwave absorption effect is significantly reduced, and the overall microwave absorption effect is reduced.

[0011] In this invention, 0.9 ≤ y ≤ 1.4, and for example, it can be 0.9, 0.98, 1.0, 1.04, 1.3, or 1.4, etc. However, it is not limited to the listed values; other unlisted values ​​within the range are also applicable.

[0012] As a preferred technical solution of the present invention, the particle size D50 of the praseodymium-dysprosium co-doped M-type hexagonal ferrite material is 0.5 to 10 μm, for example, it can be 0.5 μm, 1.0 μm, 1.3 μm, 1.7 μm, 3.5 μm or 8.0 μm, etc., but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0013] Preferably, the praseodymium-dysprosium co-doped M-type hexagonal ferrite material has a spherical polyhedral structure.

[0014] As a preferred embodiment of the present invention, the praseodymium-dysprosium co-doped M-type hexagonal ferrite material absorbs simultaneously in both the C-band and the Ku-band.

[0015] Preferably, the praseodymium-dysprosium co-doped M-type hexagonal ferrite material exhibits strong absorption in the C-band and X-band.

[0016] In this invention, strong absorption refers to a reflection loss (RL) of less than -20dB, meaning that 99% of the microwaves are absorbed.

[0017] Preferably, the C-band is 4–8 GHz, for example, 4 GHz, 6 GHz, or 8 GHz; the X-band is 8–12 GHz, for example, 8 GHz, 10 GHz, or 12 GHz; and the Ku-band is 12–18 GHz, for example, 12 GHz, 14 GHz, 16 GHz, or 18 GHz.

[0018] As a preferred technical solution of the present invention, the effective temperature range of the praseodymium-dysprosium co-doped M-type hexagonal ferrite material is -40 to 400°C, for example, it can be -40°C, 0°C, 50°C, 100°C, 150°C, 200°C, 250°C, 300°C, 350°C or 400°C, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0019] In this invention, if the operating temperature of the praseodymium-dysprosium co-doped M-type hexagonal ferrite material is too high, it will result in the loss of magnetism, thus affecting the wave absorption effect.

[0020] In a second aspect, the present invention provides a method for preparing a praseodymium-dysprosium co-doped M-type hexagonal ferrite material as described in the first aspect, the method comprising the following steps:

[0021] (1) Mix source A, iron source, praseodymium source, dysprosium source, complexing agent and solvent to obtain a mixed solution;

[0022] (2) The mixed solution and pH adjuster are mixed to obtain a gel;

[0023] (3) The gel is calcined to obtain the praseodymium-dysprosium co-doped M-type hexagonal ferrite material.

[0024] The preparation method provided by this invention has low production cost and simple process.

[0025] As a preferred technical solution of the present invention, the ratio of the total molar amount of the iron source, praseodymium source and dysprosium source in step (1) to the molar amount of source A is (7.85~12):1, for example, it can be 7.85:1, 9:1, 10:1, 11.5:1, 11.8:1 or 12:1, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0026] Preferably, the molar ratio of the iron source, praseodymium source, and dysprosium source in step (1) is (10–11.9):(0.05–1):(0.05–1). The range of the iron source selection "10–11.9" can be, for example, 10, 10.2, 10.4, 10.6, 10.8, 11, 11.2, 11.4, 11.6, or 11.8, etc.; the range of the praseodymium source selection "0.05–1" can be, for example, 0.05, 0.06, 0.07, 0.08, 0.09, or 1, etc.; and the range of the dysprosium source selection "0.05–1" can be, for example, 0.05, 0.06, 0.07, 0.08, 0.09, or 1, etc. However, these values ​​are not limited to the listed values; other unlisted values ​​within the range are also applicable.

[0027] In this invention, by adjusting the molar ratio of praseodymium source, dysprosium source and iron source, the interchangeability of tetravalent praseodymium and trivalent praseodymium can be achieved, increasing oxygen vacancies and dielectric loss.

[0028] In this invention, if the molar ratio of iron source to praseodymium source is too small, the amount of magnetic phase M-phase strontium ferrite generated will be too small, which is not conducive to magnetic loss and will easily generate impurity phases that are unfavorable to microwave absorption, such as cubic Pr3Fe5O. 12 If the molar ratio of iron source to praseodymium source is too large, ferric oxide impurity phase is easily generated, and the presence of ferric oxide phase is not conducive to microwave absorption.

[0029] In this invention, if the molar ratio of the iron source to the dysprosium source is too small, the amount of magnetic M-type strontium ferrite generated will be insufficient, which is detrimental to magnetic loss and makes it easier to generate impurity phases that are unfavorable to microwave absorption, such as cubic Dy3Fe5O. 12 If the molar ratio of iron source to dysprosium source is too large, ferric oxide impurity phase is easily generated, and the presence of ferric oxide phase is not conducive to microwave absorption.

[0030] In this invention, if the molar ratio of praseodymium source to dysprosium source is too small, the dielectric and magnetic properties of M-phase strontium ferrite cannot be well controlled by praseodymium and dysprosium ions, and effective dielectric and magnetic losses cannot be formed; if the molar ratio of praseodymium source to dysprosium source is too large, the magnetic and dielectric properties of M-type strontium ferrite cannot be well controlled by the two ions, affecting the absorption effect.

[0031] Preferably, the molar ratio of the complexing agent in step (1) to the total molar ratio of the A source, iron source, praseodymium source and dysprosium source is (1-5):1. For example, it can be 1:1, 1.5:1, 2:1, 2.5:1, 3:1, 4:1 or 5:1, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable. Preferably, it is (1-3):1.

[0032] In this invention, the addition of a specific amount of complexing agent helps to disperse iron, strontium, and rare earth ions well, forming metal complexes.

[0033] Preferably, the A source, iron source, praseodymium source and dysprosium source in step (1) independently include any one or a combination of at least two of nitrates, acetates or chlorides.

[0034] It should be noted that the purity of nitrates, acetates, or chlorides is all above analytical grade.

[0035] Preferably, the complexing agent in step (1) includes citric acid.

[0036] The mixing method described in step (1) includes:

[0037] Mix source A, iron source, praseodymium source, dysprosium source and solvent, and then add complexing agent.

[0038] As a preferred technical solution of the present invention, the pH adjuster in step (2) includes ammonia.

[0039] Preferably, the concentration of the ammonia water is 25-50%, for example, it can be 25%, 30%, 35%, 40%, 45% or 50%, etc., but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0040] Preferably, the pH value of the mixed solution in step (2) is 5 to 8.5, for example, it can be 5, 5.5, 6, 6.5, 7, 7.5 or 8.5, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0041] Preferably, after the mixed solution and pH adjuster in step (2) are mixed, they are subjected to constant temperature stirring.

[0042] Preferably, the constant temperature stirring process includes a water bath or an oil bath.

[0043] Preferably, the temperature of the constant temperature stirring treatment is 75-95℃, for example, it can be 75℃, 77℃, 80℃, 84℃, 88℃ or 95℃, etc., but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0044] As a preferred technical solution of the present invention, the roasting method in step (3) includes microwave heating and / or electric heating.

[0045] Preferably, the roasting temperature in step (3) is 1000 to 1300°C, for example, it can be 1000°C, 1050°C, 1100°C, 1120°C, 1130°C, 1150°C, 1200°C, 1250°C or 1300°C, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable, preferably 1100 to 1300°C.

[0046] Preferably, the heating rate of the roasting in step (3) is 2 to 10 °C / min, for example, it can be 2 °C / min, 3 °C / min, 4 °C / min, 5 °C / min, 8 °C / min or 10 °C / min, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable, preferably 2 to 5 °C / min.

[0047] In this invention, by controlling the heating rate of calcination within a certain range, the crystal growth time can be increased, resulting in larger grains, increasing the dielectric loss of the material, and thus improving the wave absorption effect.

[0048] Preferably, the calcination holding time in step (3) is 2 to 24 hours, for example, it can be 2 hours, 4 hours, 6 hours, 8 hours, 10 hours, 12 hours, 18 hours, 21 hours or 24 hours, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0049] Preferably, before calcining the gel described in step (3), the gel is first dried and heat-treated.

[0050] Preferably, the drying temperature is 95-125°C, for example, 95°C, 97°C, 100°C, 104°C, 108°C, 110°C, 114°C, 118°C, or 125°C, and the drying time is 8-48 hours, for example, 8 hours, 10 hours, 14 hours, 18 hours, 20 hours, 25 hours, 30 hours, 35 hours, 40 hours, or 48 hours, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0051] Preferably, the heat treatment temperature is 100-350℃, for example, it can be 100℃, 120℃, 140℃, 160℃, 180℃, 200℃, 240℃, 280℃, 300℃ or 350℃, etc., and the time is 0.1-3h, for example, it can be 0.1h, 0.5h, 1h, 1.5h, 2h, 2.5h or 3h, etc., but is not limited to the listed values, and other unlisted values ​​within the range are also applicable.

[0052] As a preferred technical solution of the present invention, the preparation method includes the following steps:

[0053] (1) Mix source A, iron source, praseodymium source, dysprosium source and solvent, and then add complexing agent to mix to obtain a mixed solution;

[0054] The total molar amount of the iron source, praseodymium source, and dysprosium source is in the molar ratio of source A to source A (7.85-12):1, the molar ratio of the iron source, praseodymium source, and dysprosium source is (10-11.9):(0.05-1):(0.05-1), and the molar amount of the complexing agent is in the molar ratio of source A to source A, iron source, praseodymium source, and dysprosium source to source A (1-5):1.

[0055] (2) Mix the mixed solution with a pH adjuster to adjust the pH to 5-8.5, and then stir at a constant temperature of 75-95°C to obtain a gel;

[0056] (3) The gel is dried at 95-125℃ for 8-48h, then heat-treated at 100-350℃ for 0.1-3h, then heated to 1000-1300℃ at a heating rate of 2-10℃ / min and calcined and held for 2-24h. After the process, the praseodymium-dysprosium-doped M-type hexagonal ferrite material is obtained.

[0057] Thirdly, the present invention provides a microwave absorbing material, the microwave absorbing material comprising the praseodymium-dysprosium co-doped M-type hexagonal ferrite material as described in the first aspect.

[0058] The numerical range described in this invention includes not only the point values ​​listed above, but also any point values ​​within the numerical ranges not listed above. Due to space limitations and for the sake of brevity, this invention will not exhaustively list all the specific point values ​​included in the range.

[0059] Compared with the prior art, the present invention has the following beneficial effects:

[0060] (1) In this invention, praseodymium and dysprosium are incorporated into M-type hexagonal ferrite. The variable valence and large ionic radius of praseodymium are utilized, combined with the Fe deficiency. 3+ Hefu Sr 2+ Or Ba 2+ The environment makes Pr 4+ This process reduces grain size and forms polyhedral aggregates. Simultaneously, the co-doping of praseodymium and dysprosium can form various impurity phases, which interact with the main phase, effectively promoting interfacial polarization. Furthermore, Pr... 3+ To Pr 4+ The conversion favors oxygen vacancies and Fe 2+ The formation of this significantly improves the dielectric properties of the material and enhances its microwave absorption properties.

[0061] (2) The praseodymium-dysprosium co-doped M-type hexagonal ferrite material provided by the present invention has the advantages of adjustable absorption frequency band, large absorption intensity, and high operating temperature. Its absorption performance is stable and it can be used as a base material for other composite materials.

[0062] (3) The preparation method provided by the present invention has low production cost and simple process. Attached Figure Description

[0063] Figure 1 The X-ray diffraction patterns are shown for the M-type hexagonal ferrite materials prepared in Example 1 and Comparative Example 2.

[0064] Figure 2 The image shows the microwave absorption effect of the praseodymium-dysprosium co-doped M-type hexagonal ferrite material prepared in Example 1.

[0065] Figure 3 This is a scanning electron microscope image of the praseodymium-dysprosium co-doped M-type hexagonal ferrite material prepared in Example 2.

[0066] Figure 4 The image shows the microwave absorption effect of the praseodymium-dysprosium co-doped M-type hexagonal ferrite material prepared in Example 2.

[0067] Figure 5 This is a scanning electron microscope image of the praseodymium-dysprosium co-doped M-type hexagonal ferrite material prepared in Example 3.

[0068] Figure 6 The image shows the microwave absorption effect of the praseodymium-dysprosium co-doped M-type hexagonal ferrite material prepared in Example 3.

[0069] Figure 7 This is a scanning electron microscope image of the praseodymium-dysprosium co-doped M-type hexagonal ferrite material prepared in Example 4.

[0070] Figure 8 The image shows the microwave absorption effect of the praseodymium-dysprosium co-doped M-type hexagonal ferrite material prepared in Example 4.

[0071] Figure 9 This is a scanning electron microscope image of the praseodymium-dysprosium co-doped M-type hexagonal ferrite material prepared in Example 5.

[0072] Figure 10 The image shows the microwave absorption effect of the praseodymium-dysprosium co-doped M-type hexagonal ferrite material prepared in Example 5.

[0073] Figure 11 This is a scanning electron microscope image of the praseodymium-dysprosium co-doped M-type hexagonal ferrite material prepared in Example 6.

[0074] Figure 12 The image shows the microwave absorption effect of the praseodymium-dysprosium co-doped M-type hexagonal ferrite material prepared in Example 6.

[0075] Figure 13 This is a scanning electron microscope image of the praseodymium-dysprosium co-doped M-type hexagonal ferrite material prepared in Example 7.

[0076] Figure 14 The image shows the microwave absorption effect of the praseodymium-dysprosium co-doped M-type hexagonal ferrite material prepared in Example 7.

[0077] Figure 15 This is a scanning electron microscope image of the praseodymium-dysprosium co-doped M-type hexagonal ferrite material prepared in Example 9.

[0078] Figure 16 The image shows the microwave absorption effect of the praseodymium-dysprosium co-doped M-type hexagonal ferrite material prepared in Example 9.

[0079] Figure 17 The image shows the microwave absorption effect of the praseodymium-dysprosium co-doped M-type hexagonal ferrite material prepared in Example 12.

[0080] Figure 18 Scanning electron microscope image of the praseodymium-dysprosium co-doped M-type hexagonal ferrite material prepared in Example 13.

[0081] Figure 19 The image shows the microwave absorption effect of the praseodymium-dysprosium co-doped M-type hexagonal ferrite material prepared in Comparative Example 1. Detailed Implementation

[0082] The technical solution of the present invention will be further illustrated below through specific embodiments. Those skilled in the art should understand that the embodiments described are merely illustrative of the present invention and should not be construed as limiting the invention in any way.

[0083] Example 1

[0084] This embodiment provides a praseodymium-dysprosium co-doped M-type hexagonal ferrite material, the chemical formula of which is SrFe. 11.9 Pr 0.05 Dy 0.05 O 19 ;

[0085] The praseodymium-dysprosium co-doped M-type hexagonal ferrite material has a particle size D50 of 5 μm and a spherical polyhedral structure.

[0086] This embodiment also provides a method for preparing the above-mentioned praseodymium-dysprosium co-doped M-type hexagonal ferrite material, the preparation method comprising the following steps:

[0087] (1) Stir and mix the strontium source, iron source, praseodymium source, dysprosium source and deionized water, then add the complexing agent and mix. After stirring for 3 hours, a mixed solution is obtained.

[0088] The strontium source is strontium nitrate, the iron source is ferric nitrate nonahydrate, the praseodymium source is praseodymium nitrate hexahydrate, the dysprosium source is dysprosium nitrate hexahydrate, and the complexing agent is an aqueous solution of citric acid monohydrate. The total molar ratio of the iron source, praseodymium source, and dysprosium source to the strontium source is 12:1, the molar ratio of the iron source, praseodymium source, and dysprosium source is 11.9:0.05:0.05, and the molar ratio of the complexing agent to the total molar ratio of the strontium source, iron source, praseodymium source, and dysprosium source is 1:1.

[0089] (2) Mix the mixed solution with the pH adjuster, adjust the pH to 7.08, and then place it in an oil bath constant temperature bath and stir at 90°C for 8 hours to obtain a gel;

[0090] The pH adjuster is 25% ammonia solution;

[0091] (3) The gel was dried in a forced-air drying oven at 105°C for 24 hours, then heat-treated at 300°C for 0.3 hours, and then calcined at 1250°C at a heating rate of 4.58°C / min and held for 21 hours. After the calcination, the praseodymium-dysprosium-doped M-type hexagonal ferrite material was obtained.

[0092] Figure 2 The diagram shows the microwave absorption effect of the praseodymium-dysprosium co-doped M-type hexagonal ferrite material prepared in this embodiment. As can be seen from the figure, it exhibits strong absorption in the low-frequency range, and in the high-frequency range, the matching thickness is relatively small, reaching 2.0 mm.

[0093] Example 2

[0094] The difference between this embodiment and embodiment 1 is that the molar ratio of iron source, praseodymium source and dysprosium source in step (1) is adjusted to 11.8:0.1:0.1.

[0095] The remaining preparation methods and parameters are consistent with those in Example 1.

[0096] Figure 3 Scanning electron microscope (SEM) images of the praseodymium-dysprosium co-doped M-type hexagonal ferrite material prepared in this embodiment are shown, with the images magnified at 25,000x (left) and 10,000x (right). As can be seen from the images, the prepared material particles are mostly hexagonal, with a particle size range of approximately 0.5–8 μm.

[0097] Figure 4 The diagram shows the microwave absorption effect of the praseodymium-dysprosium co-doped M-type hexagonal ferrite material prepared in this embodiment. It has strong absorption in the low frequency range and a small matching thickness of 1.5 mm in the high frequency range.

[0098] Example 3

[0099] The difference between this embodiment and embodiment 1 is that the molar ratio of iron source, praseodymium source and dysprosium source in step (1) is adjusted to 11.6:0.2:0.2.

[0100] The remaining preparation methods and parameters are consistent with those in Example 1.

[0101] Figure 5 Scanning electron microscope (SEM) images of the praseodymium-dysprosium co-doped M-type hexagonal ferrite material prepared in this embodiment are shown, with the images magnified at 25,000x (left) and 10,000x (right), respectively. As can be seen from the images, the prepared material particles are mostly hexagonal, with a particle size range of approximately 0.5–6 μm.

[0102] Figure 6 The diagram shows the microwave absorption effect of the praseodymium-dysprosium co-doped M-type hexagonal ferrite material prepared in this embodiment. It has strong absorption in the low frequency range and a small matching thickness of 1.5 mm in the high frequency range.

[0103] Example 4

[0104] The difference between this embodiment and embodiment 1 is that the molar ratio of iron source, praseodymium source and dysprosium source in step (1) is adjusted to 11.5:0.25:0.25.

[0105] The remaining preparation methods and parameters are consistent with those in Example 1.

[0106] Figure 7 Scanning electron microscope (SEM) images of the praseodymium-dysprosium co-doped M-type hexagonal ferrite material prepared in this embodiment are shown, with the images magnified at 25,000x (left) and 10,000x (right). As can be seen from the images, the prepared material particles are mostly hexagonal, with a particle size range of approximately 0.5–6 μm, and some "impure phase" particles begin to appear.

[0107] Figure 8 The diagram shows the microwave absorption effect of the praseodymium-dysprosium co-doped M-type hexagonal ferrite material prepared in this embodiment. It has strong absorption in the low frequency range and a small matching thickness of 2 mm in the high frequency range.

[0108] Example 5

[0109] The difference between this embodiment and embodiment 1 is that the molar ratio of iron source, praseodymium source and dysprosium source in step (1) is adjusted to 11.2:0.40:0.40.

[0110] The remaining preparation methods and parameters are consistent with those in Example 1.

[0111] Figure 9 The images show scanning electron microscope (SEM) images of the praseodymium-dysprosium co-doped M-type hexagonal ferrite material prepared in this embodiment, with the left image magnified at 25,000x and the right image magnified at 10,000x. As can be seen from the images, the prepared material particles are mostly hexagonal, with a particle size range of approximately 0.5–5 μm, and a large number of "impure phase" particles surround the main phase.

[0112] Figure 10 The diagram shows the microwave absorption effect of the praseodymium-dysprosium co-doped M-type hexagonal ferrite material prepared in this embodiment. It has strong absorption in the low frequency range and a small matching thickness of 2 mm in the high frequency range.

[0113] Example 6

[0114] The difference between this embodiment and embodiment 1 is that the molar ratio of iron source, praseodymium source and dysprosium source in step (1) is adjusted to 10.4:0.80:0.80.

[0115] The remaining preparation methods and parameters are consistent with those in Example 1.

[0116] Figure 11 The images show scanning electron microscope (SEM) images of the praseodymium-dysprosium co-doped M-type hexagonal ferrite material prepared in this embodiment, with the left image magnified at 25,000x and the right image magnified at 10,000x. As can be seen from the images, the prepared material particles are mostly hexagonal, with a particle size range of approximately 0.5–5 μm, and a large number of "impure phase" particles surround the main phase.

[0117] Figure 12 The diagram shows the microwave absorption effect of the praseodymium-dysprosium co-doped M-type hexagonal ferrite material prepared in this embodiment. It has strong absorption in the low frequency band, with the strongest absorption being -50.62dB, corresponding to an absorption frequency of 5.36GHz. In the high frequency band, the matching thickness is relatively small, reaching 1.5mm.

[0118] Example 7

[0119] The difference between this embodiment and embodiment 1 is that the molar ratio of iron source, praseodymium source and dysprosium source in step (1) is adjusted to 10:1:1.

[0120] The remaining preparation methods and parameters are consistent with those in Example 1.

[0121] Figure 13 The images show scanning electron microscope (SEM) images of the praseodymium-dysprosium co-doped M-type hexagonal ferrite material prepared in this embodiment, with the left image magnified at 25,000x and the right image magnified at 10,000x. As can be seen from the images, the prepared material particles are mostly hexagonal, with a particle size range of approximately 0.5–5 μm, and a large number of "impure phase" particles surround the main phase.

[0122] Figure 14 The diagram shows the microwave absorption effect of the praseodymium-dysprosium co-doped M-type hexagonal ferrite material prepared in this embodiment. It has strong absorption in the low frequency range and a small matching thickness of 1.5 mm in the high frequency range.

[0123] Example 8

[0124] This embodiment provides a praseodymium-dysprosium co-doped M-type hexagonal ferrite material, the chemical formula of which is SrFe. 11.8 Pr 0.10 Dy 0.10 O 19 ;

[0125] The praseodymium-dysprosium co-doped M-type hexagonal ferrite material has a particle size D50 of 5 μm and a spherical polyhedral structure.

[0126] This embodiment also provides a method for preparing the above-mentioned praseodymium-dysprosium co-doped M-type hexagonal ferrite material, the preparation method comprising the following steps:

[0127] (1) Stir and mix the strontium source, iron source, praseodymium source, dysprosium source and deionized water, then add the complexing agent and mix. After stirring for 3 hours, a mixed solution is obtained.

[0128] The strontium source is strontium nitrate, the iron source is ferric nitrate nonahydrate, the praseodymium source is praseodymium nitrate hexahydrate, the dysprosium source is dysprosium nitrate hexahydrate, and the complexing agent is an aqueous solution of citric acid monohydrate. The total molar ratio of the iron source, praseodymium source, and dysprosium source to the strontium source is 12:1, the molar ratio of the iron source, praseodymium source, and dysprosium source is 11.8:0.1:0.1, and the molar ratio of the complexing agent to the total molar ratio of the strontium source, iron source, praseodymium source, and dysprosium source is 1:1.

[0129] (2) Mix the mixed solution with the pH adjuster, adjust the pH to 7.1, and then place it in an oil bath constant temperature bath and stir at 90°C for 8 hours to obtain a gel;

[0130] The pH adjuster is 25% ammonia solution;

[0131] (3) The gel was dried in a forced-air drying oven at 105°C for 24 hours, then heat-treated at 200°C for 0.2 hours, and then heated to 1200°C at a heating rate of 5°C / min and calcined and held for 3 hours. After the process, the praseodymium-dysprosium-doped M-type hexagonal ferrite material was obtained.

[0132] Example 9

[0133] The difference between this embodiment and embodiment 8 is that the molar ratio of iron source, praseodymium source and dysprosium source in step (1) is adjusted to 10.8:0.6:0.6.

[0134] The remaining preparation methods and parameters are consistent with those in Example 8.

[0135] Figure 15 Scanning electron microscope (SEM) images of the praseodymium-dysprosium co-doped M-type hexagonal ferrite material prepared in this embodiment are shown, with the images magnified at 25,000x (left) and 10,000x (right). As can be seen from the images, the prepared material particles are mostly hexagonal, the M phase particles are relatively small, ranging from approximately 0.5 to 1 μm, and a large number of "impurity phase" particles surround the main phase.

[0136] Figure 16The diagram shows the absorption effect of the praseodymium-dysprosium co-doped M-type hexagonal ferrite material prepared in this embodiment. As can be seen from the figure, it has strong absorption in the low frequency band with a minimum reflection loss of -39.87dB, corresponding to a matching thickness of 4.0mm. In the high frequency band, the matching thickness is smaller, reaching 1.5mm.

[0137] Example 10

[0138] The difference between this embodiment and embodiment 8 is that the molar ratio of iron source, praseodymium source and dysprosium source in step (1) is adjusted to 11:0.5:0.5, and the total molar amount of iron source, praseodymium source and dysprosium source is in the molar ratio of the molar amount of strontium source to 12:1.3.

[0139] The remaining preparation methods and parameters are consistent with those in Example 8.

[0140] Example 11

[0141] The difference between this embodiment and embodiment 9 is that the molar ratio of iron source, praseodymium source and dysprosium source in step (1) is adjusted to 11.2:0.4:0.4, and the total molar amount of iron source, praseodymium source and dysprosium source is in the molar ratio of the molar amount of strontium source to 12:1.4.

[0142] The remaining preparation methods and parameters are consistent with those in Example 9.

[0143] Example 12

[0144] This embodiment provides a praseodymium-dysprosium co-doped M-type hexagonal ferrite material, the chemical formula of which is SrFe. 11.65 Pr 0.175 Dy 0.175 O 19 ;

[0145] The praseodymium-dysprosium co-doped M-type hexagonal ferrite material has a particle size D50 of 5 μm and a spherical polyhedral structure.

[0146] This embodiment also provides a method for preparing the above-mentioned praseodymium-dysprosium co-doped M-type hexagonal ferrite material, the preparation method comprising the following steps:

[0147] (1) Stir and mix the strontium source, iron source, praseodymium source, dysprosium source and deionized water, then add the complexing agent and mix. After stirring for 3 hours, a mixed solution is obtained.

[0148] The strontium source is strontium nitrate, the iron source is ferric nitrate nonahydrate, the praseodymium source is praseodymium nitrate hexahydrate, the dysprosium source is dysprosium nitrate hexahydrate, and the complexing agent is an aqueous solution of citric acid monohydrate. The molar ratio of the total molar amount of the iron source, praseodymium source, and dysprosium source to the molar amount of the strontium source is 12:1, the molar ratio of the iron source, praseodymium source, and dysprosium source is 11.65:0.175:0.175, and the molar ratio of the complexing agent to the total molar amount of the strontium source, iron source, praseodymium source, and dysprosium source is 1:1.

[0149] (2) Mix the mixed solution with the pH adjuster, adjust the pH to 7.22, and then place it in an oil bath constant temperature bath and stir at 90°C for 8 hours to obtain a gel;

[0150] The pH adjuster is 25% ammonia solution;

[0151] (3) The gel was dried in a forced-air drying oven at 105°C for 24 hours, then heat-treated at 200°C for 0.2 hours, and then heated to 1300°C at a heating rate of 5°C / min and calcined and held for 24 hours. After the heat treatment, the praseodymium-dysprosium-doped M-type hexagonal ferrite material was obtained.

[0152] Figure 17 The diagram shows the absorption effect of the praseodymium-dysprosium co-doped M-type hexagonal ferrite material prepared in this embodiment. As can be seen from the figure, it has strong absorption in the low frequency band with a minimum reflection loss of -52.30dB, corresponding to a matching thickness of 4.5mm. In the high frequency band, the matching thickness is smaller, and can reach a minimum of 1.5mm.

[0153] Example 13

[0154] The difference between this embodiment and embodiment 12 is that the molar ratio of iron source, praseodymium source and dysprosium source in step (1) is adjusted to 10.4:0.8:0.8.

[0155] The remaining preparation methods and parameters are consistent with those in Example 12.

[0156] Figure 18 The images show scanning electron microscope (SEM) images of the praseodymium-dysprosium co-doped M-type hexagonal ferrite material prepared in this embodiment, with the left image magnified at 10,000x and the right image magnified at 5,000x. As can be seen from the images, the prepared material particles are mostly hexagonal, the M-phase particles are relatively large, and the particles are tightly bound together, with a large number of "impurity phase" particles surrounding the main phase.

[0157] Example 14

[0158] The difference between this embodiment and embodiment 1 is that the molar ratio of iron source, praseodymium source and dysprosium source in step (1) is adjusted to 11.2:0.4:0.4, and Sr is replaced with Ba.

[0159] The remaining preparation methods and parameters are consistent with those in Example 1.

[0160] Example 15

[0161] The difference between this embodiment and embodiment 12 is that step (3) is adjusted as follows: the gel is dried in a forced-air drying oven at 105°C for 24 hours, then heat-treated at 200°C for 0.2 hours, then heated to 1250°C at a heating rate of 5°C / min and calcined and held for 12 hours. After the process, the praseodymium-dysprosium-doped M-type hexagonal ferrite material is obtained.

[0162] The remaining preparation methods and parameters are consistent with those in Example 12.

[0163] Example 16

[0164] The difference between this embodiment and embodiment 1 is that the molar ratio of iron source, praseodymium source and dysprosium source in step (1) is adjusted to 10:1.95:0.05.

[0165] The remaining preparation methods and parameters are consistent with those in Example 1.

[0166] Example 17

[0167] The difference between this embodiment and embodiment 1 is that the molar ratio of iron source, praseodymium source and dysprosium source in step (1) is adjusted to 10:0.05:1.95.

[0168] The remaining preparation methods and parameters are consistent with those in Example 1.

[0169] Example 18

[0170] The difference between this embodiment and embodiment 1 is that the molar ratio of iron source, praseodymium source and dysprosium source in step (1) is adjusted to 10.98:0.02:1.

[0171] The remaining preparation methods and parameters are consistent with those in Example 1.

[0172] Example 19

[0173] The difference between this embodiment and embodiment 1 is that the molar ratio of iron source, praseodymium source and dysprosium source in step (1) is adjusted to 10.98:1:0.02.

[0174] The remaining preparation methods and parameters are consistent with those in Example 1.

[0175] Comparative Example 1

[0176] The difference between this comparative example and Example 1 is that the molar ratio of iron source, praseodymium source and dysprosium source in step (1) is adjusted to 9:1.5:1.5.

[0177] The remaining preparation methods and parameters are consistent with those in Example 1.

[0178] Figure 19 The diagram shows the microwave absorption effect of the praseodymium-dysprosium co-doped M-type hexagonal ferrite material prepared in this embodiment. As can be seen from the diagram, when the doping amount of praseodymium source or dysprosium source reaches 1.5, the microwave absorption effect decreases significantly.

[0179] Comparative Example 2

[0180] The difference between this comparative example and Example 1 is that no praseodymium source is added in step (1).

[0181] The remaining preparation methods and parameters are consistent with those in Example 1.

[0182] Comparative Example 3

[0183] The difference between this comparative example and Example 1 is that no praseodymium source and dysprosium source are added in step (1).

[0184] The remaining preparation methods and parameters are consistent with those in Example 1.

[0185] Figure 1 The X-ray diffraction patterns of the M-type hexagonal ferrite materials prepared in Example 1 and Comparative Example 3 are shown, where (a) represents Comparative Example 3 and (b) represents Example 1. As can be seen from the figure, a pure M phase can be formed when x = 0.05.

[0186] Comparative Example 4

[0187] This comparative example provides a praseodymium-dysprosium co-doped M-type hexagonal ferrite material, the chemical formula of which is Sr 0.6 Fe 12 Pr 0.2 y 0.2 O 19 ;

[0188] The particle size D50 of the praseodymium-dysprosium co-doped M-type hexagonal ferrite material is 0.5-10 μm, and the praseodymium-dysprosium co-doped M-type hexagonal ferrite material has a spherical polyhedral structure.

[0189] This embodiment also provides a method for preparing the above-mentioned praseodymium-dysprosium co-doped M-type hexagonal ferrite material, the preparation method comprising the following steps:

[0190] (1) Stir and mix the strontium source, iron source, praseodymium source, dysprosium source and deionized water, then add the complexing agent and mix. After stirring for 3 hours, a mixed solution is obtained.

[0191] The strontium source is strontium nitrate, the iron source is ferric nitrate nonahydrate, the praseodymium source is praseodymium nitrate hexahydrate, the dysprosium source is dysprosium nitrate hexahydrate, and the complexing agent is an aqueous solution of citric acid monohydrate. The molar ratio of the total molar amount of the iron source, praseodymium source, and dysprosium source to the molar amount of the strontium source is 12.4:0.6, the molar ratio of the iron source, praseodymium source, and dysprosium source is 12:0.2:0.2, and the molar ratio of the complexing agent to the total molar amount of the strontium source, iron source, praseodymium source, and dysprosium source is 1:1.

[0192] (2) The mixed solution was placed in an oil bath constant temperature bath and stirred at 90°C for 8 hours to obtain a gel;

[0193] (3) The gel was dried in a forced-air drying oven at 105°C for 24 hours, then heat-treated at 250°C for 2 hours, and then calcined at 1200°C at a heating rate of 3.75°C / min and held for 3 hours. After the calcination, the praseodymium-dysprosium-doped M-type hexagonal ferrite material was obtained.

[0194] Performance testing

[0195] The materials prepared in the above embodiments and comparative examples were subjected to performance tests. Specific testing methods included: mixing the above materials with 20 wt% paraffin wax, pressing them into a ring-shaped device with an inner / outer diameter of 3 / 7 mm and a thickness of approximately 2 mm. Then, a vector network analyzer was used to measure the dynamic electromagnetic parameters using the transmission-reflection coaxial line method within a frequency range of 2-18 GHz, and the reflection loss at a certain thickness was calculated based on transmission line theory. The test results are shown in Table 1.

[0196] Table 1

[0197]

[0198]

[0199]

[0200] Note: " / " indicates that when the thickness is less than 6mm, the strongest absorption of 90% is not met.

[0201] analyze:

[0202] As shown in the table above, the praseodymium-dysprosium co-doped M-type hexagonal ferrite material prepared by this invention is a spherical polyhedron with uniform particle size distribution. It has high coercivity and saturation magnetization, strong absorption in the C-band and X-band, and can achieve simultaneous absorption in the C-band and Ku-band, thus broadening the absorption frequency band.

[0203] The data from Examples 1 and 16-17 show that if the molar ratio of iron source to praseodymium source is too small, it is difficult to generate the impurity phase SrFe that is beneficial for microwave absorption. y Pr 1-yO3 can affect the microwave absorption effect; if the molar ratio of iron source to dysprosium source is too small, there will be too little M-type strontium ferrite magnetic phase generated, which is not conducive to magnetic loss and is prone to generating impurity phases that are not conducive to microwave absorption, such as cubic Dy3Fe5O. 12 .

[0204] The data results from Examples 1 and 18-19 show that if the molar ratio of praseodymium source to dysprosium source is too small or too large, the magnetic and dielectric properties of the two ions on the M-type strontium ferrite cannot be well controlled, thus affecting the absorption effect.

[0205] The data results from Example 1 and Comparative Example 1 show that if the value of x is too large, then due to Pr 3+ To Pr 4+ Less conversion is needed, which is unfavorable for oxygen vacancies and Fe. 2+ The formation of this leads to a decrease in wave absorption performance, making it impossible for coatings with a thickness of less than 6 mm to effectively absorb electromagnetic waves (meeting the 90% absorption requirement).

[0206] The data results from Example 1 and Comparative Example 2 show that if no praseodymium source is added, the dielectric loss of the material is low, resulting in poor absorption performance. That is, coatings with a thickness of less than 6 mm cannot effectively absorb electromagnetic waves (meeting 90% absorption).

[0207] The data results from Example 1 and Comparative Example 3 show that if neither praseodymium nor dysprosium source is added, the dielectric loss of the material is significantly reduced, the absorption performance is poor, and the coating with a thickness of less than 6 mm cannot effectively absorb electromagnetic waves (meeting 90% absorption).

[0208] The applicant declares that the present invention is illustrated by the above embodiments, but the present invention is not limited to the above process steps, that is, it does not mean that the present invention must rely on the above process steps to be implemented. Those skilled in the art should understand that any improvements to the present invention, equivalent substitutions of the raw materials used in the present invention, addition of auxiliary components, selection of specific methods, etc., all fall within the protection scope and disclosure scope of the present invention.

Claims

1. A praseodymium-dysprosium co-doped M-type hexagonal ferrite material, characterized in that, The chemical formula of the praseodymium-dysprosium co-doped M-type hexagonal ferrite material is A y Fe 12-2x Pr x Dy x O 19 Where A is strontium and / or barium, 0.175≤x≤1, 0.9≤y≤1.4; The preparation method of the praseodymium-dysprosium co-doped M-type hexagonal ferrite material includes the following steps: (1) Mix source A, iron source, praseodymium source, dysprosium source, complexing agent and solvent to obtain a mixed solution; (2) The mixed solution and pH adjuster are mixed to obtain a gel; (3) The gel is calcined to obtain the praseodymium-dysprosium co-doped M-type hexagonal ferrite material; The molar ratio of the iron source, praseodymium source and dysprosium source in step (1) is (10~11.65):(0.175~1):(0.175~1).

2. The praseodymium-dysprosium co-doped M-type hexagonal ferrite material according to claim 1, characterized in that, The particle size D50 of the praseodymium-dysprosium co-doped M-type hexagonal ferrite material is 0.5~10μm; The praseodymium-dysprosium co-doped M-type hexagonal ferrite material has a spherical polyhedral structure.

3. The praseodymium-dysprosium co-doped M-type hexagonal ferrite material according to claim 1, characterized in that, The praseodymium-dysprosium co-doped M-type hexagonal ferrite material absorbs simultaneously in the C-band and Ku-band; The praseodymium-dysprosium co-doped M-type hexagonal ferrite material exhibits strong absorption in the C-band and X-band. The C-band is 4~8GHz, the X-band is 8~12GHz, and the Ku-band is 12~18GHz.

4. The praseodymium-dysprosium co-doped M-type hexagonal ferrite material according to claim 1, characterized in that, The effective temperature range of the praseodymium-dysprosium co-doped M-type hexagonal ferrite material is -40~400℃.

5. The praseodymium-dysprosium co-doped M-type hexagonal ferrite material according to claim 1, characterized in that, The ratio of the total molar amount of the iron source, praseodymium source and dysprosium source in step (1) to the molar amount of source A is (7.85~12):

1.

6. The praseodymium-dysprosium co-doped M-type hexagonal ferrite material according to claim 1, characterized in that, The molar ratio of the complexing agent in step (1) to the total molar ratio of the A source, iron source, praseodymium source and dysprosium source is (1-5):

1.

7. The praseodymium-dysprosium co-doped M-type hexagonal ferrite material according to claim 6, characterized in that, The molar ratio of the complexing agent in step (1) to the total molar ratio of the A source, iron source, praseodymium source and dysprosium source is (1-3):

1.

8. The praseodymium-dysprosium co-doped M-type hexagonal ferrite material according to claim 1, characterized in that, The A source, iron source, praseodymium source and dysprosium source mentioned in step (1) independently include any one or a combination of at least two of nitrates, acetates or chlorides; The complexing agent in step (1) includes citric acid.

9. The praseodymium-dysprosium co-doped M-type hexagonal ferrite material according to claim 1, characterized in that, The mixing method described in step (1) includes: Mix source A, iron source, praseodymium source, dysprosium source and solvent, and then add complexing agent.

10. The praseodymium-dysprosium co-doped M-type hexagonal ferrite material according to claim 1, characterized in that, The pH adjuster in step (2) includes ammonia.

11. The praseodymium-dysprosium co-doped M-type hexagonal ferrite material according to claim 10, characterized in that, The concentration of the ammonia water is 25-50%.

12. The praseodymium-dysprosium co-doped M-type hexagonal ferrite material according to claim 1, characterized in that, The pH value of the mixed solution in step (2) is 5~8.

5.

13. The praseodymium-dysprosium co-doped M-type hexagonal ferrite material according to claim 1, characterized in that, The roasting method described in step (3) includes microwave heating and / or electric heating.

14. The praseodymium-dysprosium co-doped M-type hexagonal ferrite material according to claim 1, characterized in that, The roasting temperature in step (3) is 1000~1300℃.

15. The praseodymium-dysprosium co-doped M-type hexagonal ferrite material according to claim 14, characterized in that, The roasting temperature in step (3) is 1100~1300℃.

16. The praseodymium-dysprosium co-doped M-type hexagonal ferrite material according to claim 1, characterized in that, The heating rate of the roasting in step (3) is 2~10℃ / min.

17. The praseodymium-dysprosium co-doped M-type hexagonal ferrite material according to claim 16, characterized in that, The heating rate of the roasting in step (3) is 2~5℃ / min.

18. The praseodymium-dysprosium co-doped M-type hexagonal ferrite material according to claim 1, characterized in that, The roasting time in step (3) is 2 to 24 hours.

19. The praseodymium-dysprosium co-doped M-type hexagonal ferrite material according to claim 1, characterized in that, Before calcining the gel in step (3), the gel is first dried and heat-treated.

20. The praseodymium-dysprosium co-doped M-type hexagonal ferrite material according to claim 19, characterized in that, The drying temperature is 95~125℃, and the time is 8~48h.

21. The praseodymium-dysprosium co-doped M-type hexagonal ferrite material according to claim 19, characterized in that, The heat treatment temperature is 100~350℃ and the time is 0.1~3h.

22. The praseodymium-dysprosium co-doped M-type hexagonal ferrite material according to claim 1, characterized in that, The preparation method includes the following steps: (1) Mix source A, iron source, praseodymium source, dysprosium source and solvent, and then add complexing agent to mix to obtain a mixed solution; The total molar amount of iron source, praseodymium source and dysprosium source is in the molar ratio of source A to source A (7.85~12):1, the molar ratio of iron source, praseodymium source and dysprosium source is (10~11.65):(0.175~1):(0.175~1), and the molar amount of complexing agent is in the molar ratio of source A, iron source, praseodymium source and dysprosium source to source A to source A:

1. (2) Mix the mixed solution with a pH adjuster to adjust the pH to 5~8.5, and then stir at a constant temperature of 75~95℃ to obtain a gel; (3) The gel is dried at 95~125℃ for 8-48h, then heat-treated at 100~350℃ for 0.1-3h, then heated to 1000~1300℃ at a heating rate of 2~10℃ / min and calcined and held for 2~24h. After the heat treatment, the praseodymium-dysprosium-doped M-type hexagonal ferrite material is obtained.

23. A microwave absorbing material, characterized in that, The microwave absorbing material includes the praseodymium-dysprosium co-doped M-type hexagonal ferrite material as described in any one of claims 1-22.

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