TiO2 rutile high-entropy ceramic materials with tunable dielectric absorption properties and their preparation methods

Abstract

The application belongs to the technical field of ceramic wave-absorbing materials, and relates to a TiO2 rutile high-entropy ceramic material with adjustable dielectric wave-absorbing performance and a preparation method thereof. x Fe y Nb z Cr m M n )O 2‑i , wherein M includes one or more of Al, Ta, V, Mg, Sn and Mn, the material has a wave-absorbing frequency band of 2-18 GHz, and the preparation method comprises the following steps: weighing and ball-milling component raw material oxides according to a molar ratio; drying the ball-milled mixed powder; and obtaining the high-entropy ceramic material by high-temperature sintering of the dried powder. The high-entropy ceramic material not only inherits the excellent high-temperature resistance, oxidation resistance and chemical stability of the rutile structure, but also can effectively enhance interface polarization relaxation and optimize electromagnetic parameters, thereby exhibiting excellent wide-frequency absorption performance in wave-absorbing applications.

Description

Technical Field

[0001] This invention belongs to the field of ceramic absorbing materials technology, specifically relating to TiO2 rutile high-entropy ceramic materials with tunable dielectric absorbing properties and their preparation methods. Background Technology

[0002] With the rapid development of modern radar detection technology and wireless communication systems, the use of the electromagnetic spectrum is becoming increasingly intensive, especially in the critical frequency band of 2-18 GHz (covering L, S, C, X, and Ku bands), where the electromagnetic environment has become extremely complex. In the defense and military field, to cope with multi-band radar detection, stealth materials not only need to possess strong absorption characteristics but also need to have wide-band response capabilities; while in civilian communication and electronic equipment, effective electromagnetic interference (EMI) shielding is crucial to ensuring equipment compatibility and data transmission accuracy.

[0003] Traditional microwave absorbing materials, such as ferrites and carbon-based materials, while exhibiting excellent performance at specific frequencies, often have significant limitations: ferrites have high density and poor temperature resistance, easily leading to the "Snoker limit" effect, which restricts their application in the high-frequency range; carbon materials, although lightweight, are difficult to control in terms of impedance matching, making it difficult to achieve efficient absorption over a wide frequency range. Existing research on high-entropy microwave absorbing materials largely focuses on optimizing the performance of single fixed components, lacking a universal material system that can flexibly address different frequency band requirements (from low-frequency L-band to high-frequency Ku-band) through fine-tuning of the components.

[0004] How to achieve precise adjustment of the absorption frequency band and cover a wide frequency range of 2-18 GHz by simply replacing elements while maintaining the excellent physicochemical properties of high-entropy ceramics is a technical bottleneck that urgently needs to be solved in the current research and development of high-performance absorbing materials. Summary of the Invention

[0005] This invention provides the following technical solution: a TiO2 rutile high-entropy ceramic material with tunable dielectric absorption properties, the chemical formula of which is (Ti x Fe y Nb z Cr m M n )O 2-i M includes one or more of Al, Ta, V, Mg, Sn, and Mn, where x, y, z, m, and n range from 0.01 to 0.90, the sum of x, y, z, m, and n is 1, and 0 < i < 0.15. The material is a solid solution formed by multiple elements in the redstone structure of titanium dioxide, exhibiting characteristics of high-entropy ceramics. The absorption frequency band of the material is 2-18 GHz.

[0006] Preferably, the metal ions in the material achieve complete solid solution in the crystal lattice to form a uniform high-entropy solid solution, and the material can improve its wave absorption performance across the entire frequency band of 2-18GHz by changing the element content of Al, Ta, V, Mg, Sn, and Mn.

[0007] This invention also discloses a method for preparing a TiO2 rutile high-entropy ceramic material with tunable dielectric absorption properties. This method, used to prepare the aforementioned high-entropy ceramic material, includes the following steps: Step 1: Weigh the raw material oxides of Ti, Fe, Nb, Cr and M components in molar ratio and then ball-mill them together.

[0008] Step 2: Dry the mixed powder that was ball-milled in Step 1.

[0009] Step 3: Sinter the powder dried in Step 2 at 1000-1400°C to obtain high-entropy ceramic material.

[0010] Preferably, in step 1, the raw material oxides of Ti, Fe, Nb, and Cr components include: TiO2, Fe2O3, Nb2O5, and Cr2O3; when M is Al, Ta, V, Mg, Sn, or Mn, the raw material oxides include: Al2O3, Ta2O3, MgO, V2O5, SnO2, and MnO2.

[0011] More preferably, in step 1, the molar ratio of the oxide raw materials includes: Ti:Fe:Nb:Cr:Al = 0.28:0.18:0.28:0.12:0.14. Ti:Fe:Nb:Cr:Ta = 0.32:0.18:0.22:0.18:0.10, Ti:Fe:Nb:Cr:Mn = 0.28:0.12:0.28:0.16:0.16, Ti:Fe:Nb:Cr:V = 0.22:0.12:0.22:0.22:0.22, Ti:Fe:Nb:Cr:Sn = 0.18:0.18:0.28:0.18:0.18, Ti:Fe:Nb:Cr:Mg = 0.22:0.12:0.40:0.16:0.10.

[0012] Preferably, in step 1, the ball milling solution includes ethanol and water.

[0013] More preferably, the volume ratio of ethanol to water is 1:0.8-1.2.

[0014] Preferably, in step 1, the ball milling speed is 200-800 rpm and the ball milling mixing time is 3-8 hours.

[0015] Preferably, in step 3, the heating rate during the sintering heating stage is 1-5°C / min, and the temperature is held at 1000-1400°C for 3-5 hours; then the temperature is lowered to 600-700°C at a cooling rate of 1-5°C / min and then allowed to cool naturally.

[0016] Preferably, in step 3, the sintering atmosphere includes air.

[0017] The beneficial effects of this invention are: 1. This invention uses oxides of titanium, iron, niobium, and chromium, along with oxides of the fifth element M (one of Al, Ta, V, Mg, Sn, and Mn), as raw materials. High-temperature sintering allows multiple metal elements to be uniformly distributed within the rutile lattice sites, forming a single-phase solid solution ceramic material with high entropy stability. During sintering, the lattice distortion effect caused by differences in the radii and valence states of different metal ions promotes atomic-scale disordered arrangement and homogenization of the microstructure, thereby improving the material's density and phase structure stability.

[0018] 2. The high-entropy ceramic material of this invention not only inherits the excellent high-temperature resistance, oxidation resistance, and chemical stability of the rutile structure, but also, due to its complex internal electronic structure and abundant lattice defects, can effectively enhance interfacial polarization relaxation and optimize electromagnetic parameters, thus exhibiting excellent broadband absorption performance in microwave absorbing applications. This invention achieves directional optimization of impedance matching characteristics through flexible control of the fifth component, significantly enhancing the loss capability against electromagnetic waves of different frequency bands and exploring its application potential in complex electromagnetic environments and radar stealth applications.

[0019] 3. This invention uses TiO2, Fe2O3, Nb2O5, Cr2O3, and fifth-order oxides (such as Al2O3, Ta2O5, MgO, V2O5, SnO2, and MnO2) as raw materials. Through different molar ratios and ball milling pretreatment, the components are uniformly dispersed at the micrometer scale. During high-temperature sintering, precise control of the heating program and holding time promotes sufficient solid-phase reactions in the oxides, achieving multi-principal-element solid solution within the rutile crystal structure and forming a uniform and dense high-entropy ceramic matrix. This process utilizes the lattice distortion and nanoscale inhomogeneity introduced by the high-entropy effect to construct multiple scattering centers and polarization loss mechanisms within the material, effectively adjusting the complex permittivity, improving impedance matching, and significantly enhancing microwave absorption performance. This invention uses widely available raw materials, has a simple process flow without organic solvent pollution, and possesses good environmental friendliness, sustainability, and potential for large-scale production. Attached Figure Description

[0020] Figure 1 The image shows a comparison of XRD patterns of six types of tunable rutile high-entropy ceramic materials prepared in Example 1 of the present invention, which describes the tunable dielectric absorption properties of TiO2 rutile high-entropy ceramic materials and their preparation method. Figure 2 The images show the SEM images of the microstructure of the high-entropy ceramic material prepared in Example 1 of this invention and the corresponding EDS surface scan images of the elements. Figure 3 The images shown are HRTEM high-resolution transmission electron microscope images and lattice stress-strain analysis diagrams of the high-entropy ceramic material prepared in Example 1 of this invention. Figure 4 This is a waveform absorption performance diagram of the optimal high-entropy ceramic material prepared in Example 1 of the present invention; Figure 5 This is a comparison chart of the microwave absorption performance of six different high-entropy ceramic materials with different compositions in Example 1 of the present invention; Figure 6 The above are simulation diagrams of the radar cross section (RCS) of the high-entropy ceramic material prepared in Example 1 of the present invention at different angles. Detailed Implementation

[0021] The relevant technologies of this invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of this invention, and not all embodiments. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this invention.

[0022] like Figures 1-6 As shown, in the TiO2 rutile high-entropy ceramic material with tunable dielectric absorption properties and its preparation method in this embodiment, the preparation method of the high-entropy rutile ceramic material includes the following steps: To prepare compositionally tunable rutile high-entropy ceramic microwave absorbing materials (Ti x Fe y Nb z Cr m M n )O 2-i(Where M is selected from Al, Ta, V, Mg, Sn, and Mn), firstly, the oxide raw materials are weighed according to an appropriate molar ratio and added to a ball mill jar for ball milling to ensure thorough mixing of the powder. After ball milling, the mixed powder is transferred to an oven for drying. The dried powder is then transferred to a crucible for high-temperature sintering to induce a solid-state reaction. After cooling, high-entropy ceramic powder is obtained. By changing the type of the fifth element M, the electromagnetic parameters of the material can be effectively controlled. This invention enables a single material system to flexibly move its optimal absorption peak within a wide frequency range of 2-18 GHz, thereby achieving efficient absorption of electromagnetic waves in different bands. It has the advantages of stable preparation process, strong environmental adaptability, and customizable absorption frequency band.

[0023] Furthermore, the volume ratio of ethanol to water in the ball mill jar is 1:1.

[0024] Furthermore, the range of the elements x, y, z, m, n is 0.01 ≤ x, y, z, m, n ≤ 0.90, and 0 < i < 0.15.

[0025] Furthermore, the ball mill speed is 200–800 rpm during the raw material mixing process.

[0026] Furthermore, the raw material mixing time is 3–8 hours.

[0027] Furthermore, the temperature inside the muffle furnace is 1000–1400℃, the heating rate is 1–5℃ / min, the cooling rate is 1–5℃ / min to 600–700℃, and then it is allowed to cool naturally.

[0028] Example Example 1 This embodiment (Ti) 0.28 Fe 0.18 Nb 0.28 Cr 0.12 Al 0.14 The preparation method of O2 high-entropy ceramic materials includes the following steps: First, the oxide raw materials TiO2, Fe2O3, Nb2O5, and Cr2O3 were accurately weighed according to the molar ratio of each cation in their chemical formulas (Ti:Fe:Nb:Cr:Al = 0.28:0.18:0.28:0.12:0.14) and added to a ball mill jar. The volume ratio of ethanol to water in the ball mill jar was 1:1. Then, the mixture was ball-milled at 200 rpm for 3 hours to ensure thorough mixing. After ball milling, the mixed powder was transferred to an oven for drying. The dried powder was then transferred to a crucible and placed in a muffle furnace. During the heating phase, the temperature was increased to 1200°C at a rate of 1°C / min and held at this temperature for 3 hours for high-temperature sintering. Afterward, the temperature was decreased to 600°C at a rate of 1°C / min and then allowed to cool naturally to room temperature with the furnace. The resulting product was then ground to obtain the final product.

[0029] Example 2 This embodiment (Ti) 0.32 Fe 0.18 Nb 0.22 Cr 0.18 Ta 0.10 )O 1.98 The preparation method of high-entropy ceramic materials includes the following steps: First, the oxide raw materials TiO2, Fe2O3, Nb2O5, Cr2O3, and Ta2O5 were accurately weighed according to the molar ratio of each cation in their chemical formulas (Ti:Fe:Nb:Cr:Ta = 0.32:0.18:0.22:0.18:0.10) and added to a ball mill jar. The volume ratio of ethanol to water in the ball mill jar was 1:1. Then, the mixture was ball-milled at 350 rpm for 4 hours to ensure thorough mixing. After ball milling, the mixed powder was transferred to an oven for drying. The dried powder was then transferred to a crucible and placed in a muffle furnace. During the heating phase, the temperature was increased to 1250°C at a rate of 2°C / min and held at this temperature for 4 hours for high-temperature sintering. Afterward, the temperature was decreased to 650°C at a rate of 2°C / min and then allowed to cool naturally to room temperature in the furnace. The resulting product was then ground to obtain the final product.

[0030] Example 3 This embodiment (Ti) 0.28 Fe 0.12 Nb 0.28 Cr 0.16 Mn 0.16 )O 1.85 The preparation method of high-entropy ceramic materials includes the following steps: First, the oxide raw materials TiO2, Fe2O3, Nb2O5, Cr2O3, and MnO2 were accurately weighed according to the molar ratio of each cation in their chemical formulas (Ti:Fe:Nb:Cr:Mn = 0.28:0.12:0.28:0.16:0.16) and added to a ball mill jar. The volume ratio of ethanol to water in the ball mill jar was 1:1. Subsequently, the mixture was ball-milled at 450 rpm for 5 hours to ensure thorough mixing of the powder. After ball milling, the mixed powder was transferred to an oven for drying. The dried powder was then transferred to a crucible and placed in a muffle furnace. During the heating phase, the temperature was raised to 1300°C at a rate of 3°C / min and held at this temperature for 4 hours for high-temperature sintering. Afterward, the temperature was lowered to 650°C at a rate of 3°C / min and then allowed to cool naturally to room temperature in the furnace. The final product was obtained after grinding.

[0031] Example 4 This embodiment (Ti) 0.22 Fe 0.12 Nb 0.22 Cr 0.22 V 0.22 )O 1.96 The preparation method of high-entropy ceramic materials includes the following steps: First, the oxide raw materials TiO2, Fe2O3, Nb2O5, Cr2O3, and V2O5 were accurately weighed according to the molar ratio of each cation in their chemical formulas (Ti:Fe:Nb:Cr:V = 0.22:0.12:0.22:0.22:0.22) and added to a ball mill jar. The volume ratio of ethanol to water in the ball mill jar was 1:1. Then, the mixture was ball-milled at 550 rpm for 6 hours to ensure thorough mixing. After ball milling, the mixed powder was transferred to an oven for drying. The dried powder was then transferred to a crucible and placed in a muffle furnace. During the heating phase, the temperature was increased to 1350°C at a rate of 4°C / min and held at this temperature for 5 hours for high-temperature sintering. Afterward, the temperature was decreased to 700°C at a rate of 4°C / min and then allowed to cool naturally to room temperature in the furnace. The resulting product was then ground to obtain the final product.

[0032] Example 5 This embodiment (Ti) 0.18 Fe 0.18 Nb 0.28 Cr 0.18 Sn 0.18 The preparation method of O2 high-entropy ceramic materials includes the following steps: First, the oxide raw materials TiO2, Fe2O3, Nb2O5, Cr2O3, and SnO2 were accurately weighed according to the molar ratio of each cation in their chemical formulas (Ti:Fe:Nb:Cr:Sn = 0.18:0.18:0.28:0.18:0.18) and added to a ball mill jar. The volume ratio of ethanol to water in the ball mill jar was 1:1. Then, the mixture was ball-milled at 650 rpm for 7 hours to ensure thorough mixing. After ball milling, the mixed powder was transferred to an oven for drying. The dried powder was then transferred to a crucible and placed in a muffle furnace. During the heating phase, the temperature was increased to 1400°C at a rate of 5°C / min and held at this temperature for 6 hours for high-temperature sintering. Afterward, the temperature was decreased to 700°C at a rate of 5°C / min and then allowed to cool naturally to room temperature in the furnace. The resulting product was then ground to obtain the final product.

[0033] Example 6 This embodiment (Ti) 0.22 Fe 0.12 Nb 0.40 Cr 0.16 Mg 0.10 The preparation method of O2 high-entropy ceramic materials includes the following steps: First, the oxide raw materials TiO2, Fe2O3, Nb2O5, Cr2O3, and MgO were accurately weighed according to the molar ratio of each cation in their chemical formulas (Ti:Fe:Nb:Cr:Mg = 0.22:0.12:0.40:0.16:0.10) and added to a ball mill jar. The volume ratio of ethanol to water in the ball mill jar was 1:1. Then, the mixture was ball-milled at 800 rpm for 8 hours to ensure thorough mixing. After ball milling, the mixed powder was transferred to an oven for drying. The dried powder was then transferred to a crucible and placed in a muffle furnace. During the heating phase, the temperature was increased to 1320°C at a rate of 3°C / min and held at this temperature for 5 hours for high-temperature sintering. Afterward, the temperature was decreased to 600°C at a rate of 3°C / min and then allowed to cool naturally to room temperature in the furnace. The resulting product was then ground to obtain the final product.

[0034] In summary, this invention provides a TiO2 rutile high-entropy ceramic material with tunable dielectric absorption properties and its preparation method, effectively solving the problem that existing absorbing materials cannot flexibly meet the needs of different frequency bands by fine-tuning the composition. By flexibly selecting the fifth component and precisely controlling the preparation process, the absorption frequency band can be accurately tunable in a wide frequency range of 2-18 GHz.

[0035] The high-entropy ceramic material of this invention has many advantages. From a microstructural perspective, its single-phase solid solution structure is uniform and stable. The lattice distortion effect not only improves the material's density and phase structure stability but also lays the foundation for optimizing its microwave absorption performance. In terms of microwave absorption performance, thanks to its complex electronic structure and abundant lattice defects, it can efficiently enhance interfacial polarization relaxation and optimize electromagnetic parameters, thereby achieving efficient absorption of electromagnetic waves in different frequency bands.

[0036] In practical applications, the material of this invention exhibits excellent adaptability and customizability. Whether in complex electromagnetic environments or in fields with high requirements for radar stealth, different radar absorption needs can be met by adjusting the type of the fifth component. Furthermore, its raw materials are widely available, its preparation process is simple, and it is free of organic solvent pollution. This gives the material significant advantages in large-scale production and practical applications, providing new ideas and methods for the development of high-performance radar absorbing materials, and possessing broad application prospects and market potential.

[0037] It should be emphasized that the above are merely preferred embodiments of the present invention and are not intended to limit the present invention in any way. Any simple modifications, equivalent changes and alterations made to the above embodiments based on the technical essence of the present invention shall still fall within the scope of the technical solution of the present invention.

Claims

1. A TiO2 rutile high-entropy ceramic material with tunable dielectric absorption properties, characterized in that, The chemical formula of the material is (Ti) x Fe y Nb z Cr m M n )O 2-i M includes one or more of Al, Ta, V, Mg, Sn, and Mn, where the values ​​of x, y, z, m, and n range from 0.01 to 0.90, the sum of x, y, z, m, and n is 1, and 0 < i < 0.

15. The material is a solid solution formed by multiple elements in the titanium dioxide-based redstone structure. The material also has the characteristics of high-entropy ceramics, and the absorption frequency band of the material is 2-18 GHz.

2. The TiO2 rutile high-entropy ceramic material with tunable dielectric absorption properties according to claim 1, characterized in that, The metal ions in the material achieve complete solid solution in the crystal lattice to form a uniform high-entropy solid solution. The material can improve its microwave absorption performance across the entire frequency band from 2 to 18 GHz by changing the element content of Al, Ta, V, Mg, Sn, and Mn.

3. A method for preparing a TiO2 rutile high-entropy ceramic material with tunable dielectric absorption properties, characterized in that, The preparation method is used to prepare the high-entropy ceramic material according to claim 1 or 2, and the preparation method includes the following steps: Step 1: Weigh the raw material oxides of Ti, Fe, Nb, Cr, and M components in molar ratio and then ball-mill them together. Step 2: Dry the mixed powder that was ball-milled in Step 1; Step 3: Sinter the powder dried in Step 2 at 1000-1400°C to obtain high-entropy ceramic material.

4. The method for preparing a TiO2 rutile high-entropy ceramic material with tunable dielectric absorption properties according to claim 3, characterized in that, In step 1, the raw material oxides of Ti, Fe, Nb, and Cr components include: TiO2, Fe2O3, Nb2O5, and Cr2O3; the raw material oxides of M when they are Al, Ta, V, Mg, Sn, and Mn include: Al2O3, Ta2O3, MgO, V2O5, SnO2, and MnO2.

5. The method for preparing a TiO2 rutile high-entropy ceramic material with tunable dielectric absorption properties according to claim 4, characterized in that, In step 1, the molar ratio of the oxide raw materials includes: Ti:Fe:Nb:Cr:Al = 0.28:0.18:0.28:0.12:0.

14. Ti:Fe:Nb:Cr:Ta = 0.32:0.18:0.22:0.18:0.10, Ti:Fe:Nb:Cr:Mn = 0.28:0.12:0.28:0.16:0.16, Ti:Fe:Nb:Cr:V = 0.22:0.12:0.22:0.22:0.22, Ti:Fe:Nb:Cr:Sn = 0.18:0.18:0.28:0.18:0.18, Ti:Fe:Nb:Cr:Mg = 0.22:0.12:0.40:0.16:0.

10.

6. The method for preparing a TiO2 rutile high-entropy ceramic material with tunable dielectric absorption properties according to claim 3, characterized in that, In step 1, the ball milling solution includes ethanol and water.

7. The method for preparing a TiO2 rutile high-entropy ceramic material with tunable dielectric absorption properties according to claim 6, characterized in that, The volume ratio of ethanol to water is 1:0.8-1.

2.

8. The method for preparing a TiO2 rutile high-entropy ceramic material with tunable dielectric absorption properties according to claim 3, characterized in that, In step 1, the ball milling speed is 200-800 rpm, and the ball milling mixing time is 3-8 hours.

9. The method for preparing a TiO2 rutile high-entropy ceramic material with tunable dielectric absorption properties according to claim 3, characterized in that, In step 3, the heating rate during the sintering heating stage is 1-5°C / min, and the temperature is held at 1000-1400°C for 3-8 hours; then the temperature is lowered to 600-700°C at a cooling rate of 1-5°C / min and then naturally cooled.

10. The method for preparing a TiO2 rutile high-entropy ceramic material with tunable dielectric absorption properties according to claim 3, characterized in that, In step 3, the sintering atmosphere includes air.

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