A kind of N 3- TiO2 doped microwave absorbing materials and their preparation methods
By controlling the oxygen vacancy concentration of TiO2 with N3-doping to form complex defect clusters, the polarization loss and electromagnetic wave dissipation capabilities are enhanced, solving the problem of weak polarization response of pure rutile TiO2 and achieving high-efficiency wave absorption performance.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- XIAN INT UNIV
- Filing Date
- 2026-03-25
- Publication Date
- 2026-06-26
Smart Images
Figure CN122294474A_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of microwave absorbing materials technology, and relates to polarization loss type microwave absorbing materials, specifically an N... 3- TiO2-doped microwave absorbing materials and their preparation methods. Background Technology
[0002] With the rapid development of modern electronic information technology, wireless communication, radar detection, and electromagnetic compatibility technology, electromagnetic waves are widely used in military, civilian, industrial, and consumer electronics fields. However, this has also led to increasingly prominent problems such as electromagnetic interference, electromagnetic radiation pollution, and radar detection and counter-detection. Traditional electromagnetic protection and stealth methods mainly rely on reflection and shielding, which can easily cause secondary electromagnetic pollution. This pollution can interfere with the normal operation of precision electronic equipment, threatening information security and biological health. Absorbing materials can convert the energy of incident electromagnetic waves into heat or other forms of energy dissipation through mechanisms such as dielectric loss, magnetic loss, interface polarization, and multiple scattering, thereby achieving efficient absorption and attenuation of electromagnetic waves. They have significant application value in stealth equipment, microwave anechoic chambers, 5G communication, and anti-interference of electronic equipment. Among these, TiO2 possesses advantages such as good chemical stability, high temperature resistance, corrosion resistance, low density, environmental friendliness, and low cost, making it more promising than traditional magnetic absorbing materials under harsh conditions such as high temperature and corrosion.
[0003] However, pure rutile TiO2 has a wide intrinsic bandgap (3.2 eV) and low carrier concentration, resulting in extremely weak polarization response in the microwave band and insufficient absorption performance when used alone as an absorbing material. Currently, although metal ion doping of TiO2 can improve its absorption performance to some extent, there are still significant shortcomings, such as the easy introduction of carrier recombination centers, easy segregation failure at high temperatures, and insufficient precision in the synergistic control of defect concentration and dielectric properties; it also generally suffers from problems such as difficulty in balancing impedance matching and high loss, and narrow effective absorption bandwidth, making it difficult to meet the application requirements of next-generation broadband, strong absorption, thin-layer, and high stability. Summary of the Invention
[0004] The purpose of this invention is to provide an N 3- TiO2-doped microwave absorbing materials and their preparation methods, using N 3- Doping with TiO2 achieves O 2 By replacing oxygen vacancy concentration, polarization loss and electromagnetic wave dissipation are enhanced, resulting in strong absorption and wide bandwidth, thus achieving high-efficiency wave absorption of a single TiO2-based material.
[0005] This invention is achieved through the following technical solution: A kind of N 3- The molar ratio of N to Ti in the TiO2 doped microwave absorbing material is (1.0~2.4):1.
[0006] This invention also protects a N described above. 3- The preparation method of TiO2-doped microwave absorbing material includes the following steps: Step 1: According to the stoichiometric ratio, measure out tetrabutyl titanate and ammonia water respectively. Add the measured amounts of the two raw materials to anhydrous ethanol in sequence, and then add deionized water dropwise. Stir until a wet gel is formed. The volume ratio of tetrabutyl titanate, anhydrous ethanol and deionized water is 1:(5~9):(0.2~0.9). Step 2: Aging the wet gel formed in Step 1 at room temperature for 6-15 hours, and then drying it in an oven to obtain dry gel powder; Step 3: The dry gel powder formed in Step 2 is pre-pressed into a cylindrical blank using a mold, placed in a tube furnace, and heated from room temperature to 1000~1150 ℃ under a nitrogen atmosphere, held at that temperature for 4~8 h, and then cooled to 500 ℃ at a cooling rate of 10 ℃ / min. It is then allowed to cool naturally to room temperature to obtain N. 3- TiO2-doped microwave absorbing material.
[0007] Preferably, the stirring in step one is performed at room temperature using a magnetic stirrer for 15-25 hours.
[0008] Preferably, the drying in step two involves drying in an oven at 50-80°C for 24-96 hours.
[0009] Compared with the prior art, the present invention has the following technical effects: This invention uses N 3- Doping achieves O in the TiO2 lattice 2- Replacement, low-valence state N 3- The introduction of N generates oxygen vacancies during charge compensation, with different molar ratios of N 3- Doping modulates the oxygen vacancy concentration and occupies O 2 and form Point defects and complex defect clusters: The coordinated construction of complex defect clusters by multiple point defects facilitates electron localization, constructs novel defect dipoles, and significantly enhances polarization loss and electromagnetic wave dissipation capability; When the N / Ti molar ratio is 1.7, the material achieves an optimal reflection loss (RL) of -37.5 dB and an effective absorption bandwidth (EAB) of 3.4 GHz with a thickness of 2.0 mm, exhibiting both strong absorption and wide bandwidth characteristics, thus solving the inherent defects of weak polarization response and poor wave absorption performance of pure rutile TiO2; This invention does not require compositing with carbon materials, magnetic materials, etc. It can obtain high reflection loss and wide absorption frequency range in a single TiO2 material by controlling the defect structure of TiO2 itself through anion doping. It provides a new method for the design and development of TiO2-based microwave absorbing materials and breaks through the technical limitations of existing TiO2-based microwave absorbing materials that rely on composite modification. This invention uses the sol-gel method for preparation, which is simple, convenient, and uses readily available and low-cost raw materials. It also has a high yield during preparation and is easy to scale up, thus having good prospects for industrial application. This invention enables continuous control of the oxygen vacancy concentration in TiO2 by adjusting the N / Ti molar ratio, thereby achieving directional control of the material's microwave absorption performance. The doping ratio can be adjusted according to actual application requirements to adapt to different electromagnetic protection, stealth and other application scenarios. This invention retains the stable physicochemical properties and environmentally friendly characteristics of TiO2 itself. After nitrogen heat treatment, the material has a rutile crystal phase and excellent structural stability, laying the foundation for its practical application. Attached Figure Description
[0010] Figure 1 The XRD patterns of the samples prepared in Examples 1 to 3 and Comparative Example 1; Figure 2 The RL values of the samples prepared in Examples 1 to 3 and Comparative Example 1 at different thicknesses (1.7 mm, 2.0 mm, 2.3 mm, 2.6 mm) as a function of frequency (2-18 GHz) are shown. Figure 3 The RL and EAB spectra of the samples prepared in Examples 1 to 3 and Comparative Example 1 at 2.0 mm are shown. Detailed Implementation
[0011] The present invention will be further described in detail below with reference to specific embodiments. These descriptions are for explanation purposes only and are not intended to limit the scope of the invention.
[0012] Example 1 This embodiment provides an N 3- The preparation method of the TiO2-doped microwave absorbing material, with a molar ratio of N to Ti of 1.0:1, includes the following steps: Step 1: According to the stoichiometric ratio, measure 7.0 mL of tetrabutyl titanate with a purity of 98.0%, 3 mL of ammonia with a purity of 28.0%, 45 mL of anhydrous ethanol with a purity of 99.5%, and 3.0 mL of deionized water. Using anhydrous ethanol as the solvent, stir continuously with a magnetic stirrer at room temperature for 25 h, then age for 15 h, transfer to an oven at 60 ℃ to dry for 24 h, and grind thoroughly with a mortar for 10 min to obtain dry gel powder. Step 2: The dry gel powder is pre-pressed into cylindrical blanks with a diameter of 8 mm using a mold. These blanks are then placed in a tube furnace and heated from room temperature to 1000 °C under a nitrogen atmosphere. The temperature is held for 8 hours, then reduced to 500 °C at a cooling rate of 10 °C / min. Finally, the powder is allowed to cool naturally to room temperature to obtain anionic (N...) gels. 3 TiO2-doped microwave absorbing material.
[0013] Nitrogen heat-treated anions (N) 3- TiO2-doped microwave absorbing material was then thoroughly ground in a mortar. The microwave absorbing material was then thoroughly mixed with molten paraffin at a filling ratio of 4:6 and pressed into hollow ring-shaped samples with an outer diameter of 7.0 mm, an inner diameter of 3.04 mm, and thicknesses of 1.7 mm, 2.0 mm, 2.3 mm, and 2.6 mm, respectively.
[0014] Example 2 This embodiment provides an N 3- The preparation method of the TiO2-doped microwave absorbing material, with a molar ratio of N to Ti of 1.7:1, includes the following steps: Step 1: According to the stoichiometric ratio, measure 7.0 mL of tetrabutyl titanate with a purity of 98.0%, 5 mL of ammonia with a purity of 28.0%, 52 mL of anhydrous ethanol with a purity of 99.5%, and 3.5 mL of deionized water. Using anhydrous ethanol as the solvent, stir continuously with a magnetic stirrer at room temperature for 25 h, then age for 15 h, transfer to an oven at 60 ℃ to dry for 24 h, and grind thoroughly with a mortar for 10 min to obtain dry gel powder. Step 2: The dry gel powder is pre-pressed into cylindrical blanks with a diameter of 8 mm using a mold. These blanks are then placed in a tube furnace and heated from room temperature to 1150 °C under a nitrogen atmosphere. The temperature is held for 4 hours, then reduced to 500 °C at a cooling rate of 10 °C / min. Finally, the powder is allowed to cool naturally to room temperature to obtain anionic (N...) gels. 3- TiO2-doped microwave absorbing material.
[0015] Nitrogen heat-treated anions (N) 3- TiO2-doped microwave absorbing material was then thoroughly ground in a mortar. The microwave absorbing material was then thoroughly mixed with molten paraffin at a filling ratio of 4:6 and pressed into hollow ring-shaped samples with an outer diameter of 7.0 mm, an inner diameter of 3.04 mm, and thicknesses of 1.7 mm, 2.0 mm, 2.3 mm, and 2.6 mm, respectively.
[0016] Example 3 This embodiment provides an N 3- The preparation method of the TiO2-doped microwave absorbing material, with a molar ratio of N to Ti of 2.4:1, includes the following steps: Step 1: According to the stoichiometric ratio, measure 7.0 mL of tetrabutyl titanate with a purity of 98.0%, 7 mL of ammonia with a purity of 27.0%, 59 mL of anhydrous ethanol with a purity of 99.5%, and 4.0 mL of deionized water. Using anhydrous ethanol as the solvent, stir continuously with a magnetic stirrer at room temperature for 25 h, then age for 15 h, transfer to an oven at 60 ℃ to dry for 24 h, and grind thoroughly with a mortar for 10 min to obtain dry gel powder. Step 2: The dry gel powder is pre-pressed into cylindrical blanks with a diameter of 8 mm using a mold. These blanks are then placed in a tube furnace and heated from room temperature to 1100 °C under a nitrogen atmosphere. The temperature is held for 6 hours, then reduced to 500 °C at a cooling rate of 10 °C / min. Finally, the powder is allowed to cool naturally to room temperature to obtain anionic (N...) gels. 3- TiO2-doped microwave absorbing material.
[0017] Nitrogen heat-treated anions (N) 3- TiO2-doped microwave absorbing material was then thoroughly ground in a mortar. The microwave absorbing material was then thoroughly mixed with molten paraffin at a filling ratio of 4:6 and pressed into hollow ring-shaped samples with an outer diameter of 7.0 mm, an inner diameter of 3.04 mm, and thicknesses of 1.7 mm, 2.0 mm, 2.3 mm, and 2.6 mm, respectively.
[0018] Example 4 This embodiment provides an N 3- The preparation method of the TiO2-doped microwave absorbing material, with a molar ratio of N to Ti of 1.7:1, includes the following steps: Step 1: According to the stoichiometric ratio, measure 7.0 mL of tetrabutyl titanate with a purity of 98.0%, 5 mL of ammonia with a purity of 28.0%, 63 mL of anhydrous ethanol with a purity of 99.5%, and 4.2 mL of deionized water. Using anhydrous ethanol as the solvent, stir continuously with a magnetic stirrer at room temperature for 20 h, then age for 10 h, transfer to an oven at 80 ℃ to dry for 48 h, and grind thoroughly with a mortar for 10 min to obtain dry gel powder. Step 2: The dry gel powder is pre-pressed into cylindrical blanks with a diameter of 8 mm using a mold. These blanks are then placed in a tube furnace and heated from room temperature to 1150 °C under a nitrogen atmosphere. The temperature is held for 4 hours, then reduced to 500 °C at a cooling rate of 10 °C / min. Finally, the powder is allowed to cool naturally to room temperature to obtain anionic (N...) gels. 3- TiO2-doped microwave absorbing material.
[0019] Nitrogen heat-treated anions (N) 3-TiO2-doped microwave absorbing material was then thoroughly ground in a mortar. The microwave absorbing material was then thoroughly mixed with molten paraffin at a filling ratio of 4:6 and pressed into hollow ring-shaped samples with an outer diameter of 7.0 mm, an inner diameter of 3.04 mm, and thicknesses of 1.7 mm, 2.0 mm, 2.3 mm, and 2.6 mm, respectively.
[0020] Example 5 This embodiment provides an N 3- The preparation method of the TiO2-doped microwave absorbing material, with a molar ratio of N to Ti of 1.7:1, includes the following steps: Step 1: According to the stoichiometric ratio, measure 7.0 mL of tetrabutyl titanate with a purity of 98.0%, 5 mL of ammonia with a purity of 28.0%, 35 mL of anhydrous ethanol with a purity of 99.5%, and 2.3 mL of deionized water. Using anhydrous ethanol as the solvent, stir continuously with a magnetic stirrer at room temperature for 25 h, then age for 15 h, transfer to an oven at 60 ℃ to dry for 24 h, and grind thoroughly with a mortar for 10 min to obtain dry gel powder. Step 2: The dry gel powder is pre-pressed into cylindrical blanks with a diameter of 8 mm using a mold. These blanks are then placed in a tube furnace and heated from room temperature to 1150 °C under a nitrogen atmosphere. The temperature is held for 4 hours, then reduced to 500 °C at a cooling rate of 10 °C / min. Finally, the powder is allowed to cool naturally to room temperature to obtain anionic (N...) gels. 3- TiO2-doped microwave absorbing material.
[0021] Nitrogen heat-treated anions (N) 3- TiO2-doped microwave absorbing material was then thoroughly ground in a mortar. The microwave absorbing material was then thoroughly mixed with molten paraffin at a filling ratio of 4:6 and pressed into hollow ring-shaped samples with an outer diameter of 7.0 mm, an inner diameter of 3.04 mm, and thicknesses of 1.7 mm, 2.0 mm, 2.3 mm, and 2.6 mm, respectively.
[0022] Comparative Example 1 This embodiment provides an N 3- The preparation method of the TiO2-doped microwave absorbing material, with a molar ratio of N to Ti of 0.3:1, includes the following steps: Step 1: According to the stoichiometric ratio, measure 7.0 mL of tetrabutyl titanate with a purity of 98.0%, 1 mL of ammonia with a purity of 25.0%, 38 mL of anhydrous ethanol with a purity of 99.5%, and 2.5 mL of deionized water. Using anhydrous ethanol as the solvent, stir continuously with a magnetic stirrer at room temperature for 25 h, then age for 15 h, transfer to an oven at 60 ℃ to dry for 24 h, and grind thoroughly with a mortar for 10 min to obtain dry gel powder. Step 2: The dry gel powder is pre-pressed into cylindrical blanks with a diameter of 8 mm using a mold. These blanks are then placed in a tube furnace and heated from room temperature to 1000 °C under a nitrogen atmosphere. The temperature is held for 8 hours, then reduced to 500 °C at a cooling rate of 10 °C / min. Finally, the powder is allowed to cool naturally to room temperature to obtain anionic (N...) gels. 3- TiO2-doped microwave absorbing material.
[0023] Nitrogen heat-treated anions (N) 3- TiO2-doped microwave absorbing material was then thoroughly ground in a mortar. The microwave absorbing material was then thoroughly mixed with molten paraffin at a filling ratio of 4:6 and pressed into hollow ring-shaped samples with an outer diameter of 7.0 mm, an inner diameter of 3.04 mm, and thicknesses of 1.7 mm, 2.0 mm, 2.3 mm, and 2.6 mm, respectively.
[0024] Figure 1 The XRD patterns of the samples prepared in Examples 1 to 3 and Comparative Example 1 are shown. The diffraction peaks of the samples in the patterns highly match the standard PDF card #21-1276 for rutile TiO2, and no obvious impurity phase peaks appear, indicating that four TiO2 microwave absorbing materials with rutile as the main phase have been prepared, and N 3- The doping did not change the rutile crystal structure of TiO2, but only achieved lattice substitution of anions.
[0025] Figure 2 The graphs show the variation of RL (Rapid Reduction) with frequency (2-18 GHz) for samples prepared in Examples 1 to 3 and Comparative Example 1 at different thicknesses (1.7 mm, 2.0 mm, 2.3 mm, 2.6 mm). (a), (b), (c), and (d) are four sub-graphs, corresponding to the molar ratio of N to Ti, respectively. x The RL values for samples with N = 0.3, 1.0, 1.7, and 2.4 at thicknesses of 1.7 mm, 2.0 mm, 2.3 mm, and 2.6 mm were calculated. When the molar ratio of N to Ti was 0.3, 1.0, 1.7, and 2.4, the optimal RL values at a 2.0 mm thickness were -4.3 dB, -39.5 dB, -37.5 dB, and -32.3 dB, respectively. x When the doping concentration is 0.3, the sample has no absorption properties (RL = -4.3 dB), indicating that low doping concentration cannot form effective defect clusters and polarization loss. x When the ≥ 1.0, the sample exhibits good absorption performance, with RL values all below -30 dB. x When the ratio is 1.0, the RL reaches -39.5 dB, which is the optimal absorption intensity. x When the value is further increased to 1.7 and 2.4, although the RL decreases slightly, it indicates that N doping can effectively improve the microwave absorption performance of rutile TiO2.
[0026] Figure 3 The EAB spectra of the samples prepared in Examples 1 to 3 and Comparative Example 1 at 2.0 mm are shown. The EAB values are 0 GHz, 2.6 GHz, 3.4 GHz, and 3.2 GHz, respectively. Wherein, when x At a value of 1.7, the absorbing material has both -37.5 dB RL and 3.4 GHz EAB, balancing absorption intensity and effective bandwidth.
[0027] It should be noted that the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.
Claims
1. A kind of N 3- TiO2-doped microwave absorbing material, characterized in that, The molar ratio of N to Ti is (1.0~2.4):
1.
2. A method for applying N according to claim 1 3- The method for preparing TiO2-doped microwave absorbing materials is characterized by, Includes the following steps: Step 1: According to the stoichiometric ratio, measure out tetrabutyl titanate and ammonia water respectively. Add the measured amounts of the two raw materials to anhydrous ethanol in sequence, and then add deionized water dropwise. Stir until a wet gel is formed. The volume ratio of tetrabutyl titanate, anhydrous ethanol and deionized water is 1:(5~9):(0.2~0.9). Step 2: Aging the wet gel formed in Step 1 at room temperature for 6-15 hours, and then drying it in an oven to obtain dry gel powder; Step 3: The dry gel powder formed in Step 2 is pre-pressed into a cylindrical blank using a mold, placed in a tube furnace, and heated from room temperature to 1000~1150 ℃ under a nitrogen atmosphere, held at that temperature for 4~8 h, and then cooled to 500 ℃ at a cooling rate of 10 ℃ / min. It is then allowed to cool naturally to room temperature to obtain N. 3- TiO2-doped microwave absorbing material.
3. The N according to claim 2 3- The method for preparing TiO2-doped microwave absorbing materials is characterized by, The stirring described in step one involves stirring at room temperature using a magnetic stirrer for 15-25 hours.
4. The N according to claim 2 3- The method for preparing TiO2-doped microwave absorbing materials is characterized by, The drying process described in step two involves drying the food in an oven at 50-80°C for 24-96 hours.