High-entropy rare earth Fe-based garnet composite MXene material and preparation method thereof

Abstract

The invention belongs to the technical field of ceramic composite material preparation, and relates to a high-entropy rare earth Fe-based garnet composite MXene material and a preparation method thereof, the general formula of the material is (ErxGdyEuzSmmNdn) 3Fe5O12 (at) MXene, the preparation method comprises the following steps: 1, weighing rare earth oxide raw materials in proportion, and carrying out ball milling treatment to obtain mixed powder; 2, the mixed powder is dried; 3, sintering the dried mixed powder at high temperature, and cooling to obtain high-entropy ceramic powder; and 4, carrying out surface modification on the high-entropy ceramic powder by using a PDDA solution, mixing with single-layer MXene, and collecting to finally obtain the high-entropy ceramic material. The rare earth oxide and the iron oxide are adopted as raw materials, various metal elements are uniformly distributed in a garnet structure through high-temperature sintering, the ceramic material with high entropy stability is formed, the ceramic material has high specific surface area and good electromagnetic wave isolation characteristics, the wave absorbing treatment effect can be remarkably enhanced, and the application prospect is wide. The method has application potential in the fields of electromagnetic shielding, radar stealth and the like.

Description

Technical Field

[0001] The present invention belongs to the technical field of ceramic composite material preparation, and relates to a high-entropy rare-earth Fe-based garnet composite MXene material and a preparation method thereof. Background Art

[0002] With the increasingly strict requirements for the electromagnetic environment in modern electronic devices and military equipment, controlling and managing the propagation of electromagnetic waves has become an important means to improve the concealment and stability of the system. In the fields of national defense and civil use, designing efficient electromagnetic wave absorbing materials can not only weaken the electromagnetic characteristics of the target, but also effectively alleviate system failures caused by electromagnetic interference, ensuring the security and reliability of communication and signal transmission. In recent years, researchers have been exploring the use of new materials to break through the bottleneck of traditional electromagnetic wave absorbing technologies. Among them, high-entropy ceramics, with their solid solution structure composed of multiple elements, exhibit outstanding thermal stability, chemical corrosion resistance, and mechanical strength, and at the same time show unique advantages in the regulation of dielectric and magnetic losses. At the same time, MXene, this two-dimensional material, shows potential in electromagnetic energy conversion and absorption due to its ultra-large specific surface area and rich surface functional groups.

[0003] However, MXene often faces problems such as sheet agglomeration and uneven dispersion in practical applications, which makes it difficult to fully exert its electromagnetic absorption performance in the composite system.

[0004] Therefore, a ceramic material with a uniform distribution of multiple metal elements and high entropy stability is needed to solve the above technical problems. Summary of the Invention

[0005] To solve the above problems, the present invention combines high-entropy ceramics with MXene materials, and optimizes the microstructure of the composite material through a synergistic effect, which not only helps to improve the uniform distribution of MXene sheets, but also enhances the interfacial interaction, thereby improving the overall electromagnetic wave absorption efficiency and environmental stability.

[0006] The technical solution adopted by the present invention to solve the technical problems is: a high-entropy rare-earth Fe-based garnet composite MXene material, whose general formula is: (Er x Gd y Eu z Sm m Nd n )3Fe5O 12 @MXene; wherein, the value ranges of x, y, z, m, and n are 0.1 to 0.9 respectively.

[0007] Preferably, the high-entropy rare-earth Fe-based garnet composite MXene material is a solid solution formed by rare-earth elements Er, Gd, Eu, Sm, and Nd in the Fe-based garnet structure, featuring the characteristics of high-entropy ceramics. In the high-entropy rare-earth Fe-based garnet composite MXene material, rare-earth ions are completely solid-solved in the garnet lattice to form a homogeneous high-entropy solid solution, and the composite MXene material further enhances the wave-absorbing performance.

[0008] Preferably, the value ranges of x, y, z, m, and n are 0.3 to 0.7 respectively.

[0009] The present invention also discloses a preparation method of a high-entropy rare-earth Fe-based garnet composite MXene material, which is used to prepare the above-mentioned high-entropy rare-earth Fe-based garnet composite MXene material. The preparation method includes the following steps:

[0010] Step 1: After weighing the rare-earth oxide raw materials in proportion, perform ball milling treatment to fully mix the raw materials to obtain a mixed powder.

[0011] Step 2: After the ball milling is completed, dry the mixed powder obtained in Step 1.

[0012] Step 3: Perform high-temperature sintering on the dried mixed powder in Step 2, cool down after high-temperature sintering, and obtain high-entropy ceramic powder.

[0013] Step 4: Collect the high-entropy ceramic powder obtained in Step 3 after surface modification with PDDA solution and mixing with monolayer MXene to finally obtain a high-entropy ceramic material. Immerse the ceramic powder in PDDA (poly(diallyldimethylammonium chloride)) solution for surface modification. Since PDDA is a cationic polymer with a positive charge, it is adsorbed on the surface of the ceramic powder through electrostatic interaction, making its surface positively charged or enhancing its surface charge density, thereby improving the binding ability with other materials. Mix the surface-modified ceramic powder with monolayer MXene (two-dimensional transition metal carbides / nitrides nanosheets). Since MXene is usually negatively charged, the PDDA-modified ceramic powder can be tightly combined with MXene through electrostatic attraction to form a uniform composite structure.

[0014] Preferably, in Step 1, the rare-earth oxides include: Er2O3, Sm2O3, Gd2O3, Nd2O3, Eu2O3, and Fe2O3; the ratio in the proportional weighing is a molar ratio.

[0015] Preferably, in Step 1, the co-permeation medium for the ball milling treatment includes: ethanol, water; the volume ratio of ethanol to water in the co-permeation medium is 1:0.8 to 1.2.

[0016] Preferably, in step 1, during the ball milling process, the rotational speed of the ball milling machine is 200 - 800 rmp, and the ball milling time for the mixed raw materials is 3 - 8 hours.

[0017] More preferably, in step 3, during high-temperature sintering, the temperature is raised to 1200 - 1400 °C at a heating rate of 1 - 5 °C / min in the heating stage and held at this temperature for 3 - 5 hours; during cooling, the temperature is lowered to 600 - 700 °C at a cooling rate of 1 - 5 °C / min and then cooled naturally.

[0018] Preferably, in step 4, the PDDA solution is prepared from an aqueous solution, and the volume ratio of PDDA to water is (1 - 3):2000; the dosage ratio of monolayer MXene to high-entropy ceramic is 1 - 5 ml:1 mg; the dosage ratio of the PDDA solution to high-entropy ceramic is 1 ml:1 - 5 mg.

[0019] Preferably, in step 4, when the high-entropy ceramic is compounded with MXene, the stirring speed is 300 - 600 rpm, and the stirring time is 0.5 - 2 hours.

[0020] The beneficial effects of the present invention are as follows:

[0021] 1. The present invention uses rare earth oxides and iron oxides as raw materials, and through high-temperature sintering, a variety of metal elements are evenly distributed in the garnet structure to form a ceramic material with high entropy stability.

[0022] 2. During the sintering process of the present invention, due to the differences in the melting points and properties of each component, it can promote grain refinement and component homogenization, thereby improving the density and stability of the material. This high-entropy ceramic material not only exhibits strong high-temperature resistance and corrosion resistance, but also due to its special crystal structure, it can effectively scatter and absorb electromagnetic waves, thus having excellent performance in wave absorption applications. It has a high specific surface area with a combination of multiple metal elements and good electromagnetic wave isolation characteristics, which can significantly enhance the wave absorption treatment effect and has application potential in the fields of electromagnetic shielding and radar stealth.

[0023] 3. The present invention uses Er2O3, Sm2O3, Gd2O3, Nd2O3, Eu2O3 and Fe2O3 as raw materials. Through molar ratio measurement and ball milling for pretreatment, the components are uniformly dispersed at the micron scale. During the high-temperature sintering process, by precisely controlling the heating rate, solid-phase reactions occur among the oxides, and they are fully dissolved in the garnet crystal structure to form a uniform high-entropy ceramic matrix. Subsequently, the sintered product is surface-modified with PDDA solution, enabling a modified layer with abundant active functional groups to be generated on the material surface, thereby effectively enhancing the interaction between the interface and electromagnetic waves, improving impedance matching, and significantly enhancing the wave absorption performance. The method has a wide range of raw material sources, a simple process, and is environmentally friendly, with good sustainability and potential for large-scale production. Description of the Drawings

[0024] Figure 1 is the XRD patterns of MXene, (Er x Gd y Eu z Sm m Nd n )3Fe5O 12 @MXene and MAX materials before and after sintering and the XRD pattern of the raw material MAX;

[0025] Figure 2 is the SEM image of the high-entropy ceramic material prepared in Example 1 of the present invention;

[0026] Figure 3 is the EDS image of the high-entropy ceramic material prepared in Example 1 of the present invention;

[0027] Figure 4 is the SEM image of the MXene material prepared in Example 1 of the present invention;

[0028] Figure 5 is the SEM image of the high-entropy ceramic @MXene composite material prepared in Example 1 of the present invention;

[0029] Figure 6 is the HRTEM image of the MXene prepared in Example 1 of the present invention;

[0030] Figure 7 is the HRTEM image of the high-entropy ceramic material prepared in Example 1 of the present invention;

[0031] Figure 8 is the schematic diagram of the reflection loss of the high-entropy ceramic @MXene composite material prepared in Example 1 of the present invention;

[0032] Figure 9Electromagnetic parameter diagram of the high-entropy ceramic@MXene composite material prepared in the first embodiment of the present invention;

[0033] Figure 10 RCS simulation diagram of the high-entropy ceramic@MXene composite material prepared in the first embodiment of the present invention. Specific implementation manners

[0034] The following will clearly and completely describe the related technologies in the present invention with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0035] Reference Figures 1 to 10 As shown, the high-entropy rare-earth Fe-based garnet composite MXene material and its preparation method in this specific implementation manner. To prepare the high-entropy rare-earth Fe-based garnet material (Er x Gd y Eu z Sm m Nd n )3Fe5O 12 , first, the oxide raw materials are weighed according to an appropriate molar ratio and added to a ball mill tank for ball milling to ensure sufficient mixing of the powders. After ball milling, the mixed powders are transferred to an oven for drying. The dried powders are then transferred to a crucible for high-temperature sintering, and after cooling, high-entropy ceramic powders are obtained. The obtained high-entropy ceramics are surface-modified with PDDA solution and then mixed with monolayer MXene and collected.

[0036] The volume ratio of ethanol to water in the ball mill tank is 1:1; the compositional ranges of x, y, z, m, and n are 0.10 to 0.90; during the mixing of the raw materials, the rotation speed of the ball mill machine is 200 to 800 rmp, and the mixing time of the raw materials is 3 to 8 hours; the temperature in the muffle furnace is 1200 to 1400 °C, the heating rate is 1 to 5 °C / min, and the cooling rate is 1 to 5 °C / min until it reaches 600 to 700 °C and then cools naturally. The dosage of monolayer MXene is in the range of 1 to 5 ml; the volume ratio of PDDA to water is (1 to 3):2000; each 1 ml of PDDA solution contains 1 to 5 mg of high-entropy ceramic; in the step of compounding high-entropy ceramic and MXene, the stirring speed is 300 to 600 rpm, and the stirring time is 0.5 to 2 hours.

[0037] Examples

[0038] The preparation method of the high-entropy rare-earth Fe-based garnet material and its composite material in this example includes the following steps:

[0039] After weighing the oxide raw materials in appropriate molar ratios, they are added to a ball milling jar and ball milled to be fully mixed. After drying in an oven, they are removed and transferred to a muffle furnace for high-temperature heating to undergo solid-state reactions to obtain high-entropy ceramic materials. After mixing and reacting the single-layer MXene material with PDDA surface-modified high-entropy ceramics, a high-entropy rare-earth Fe-based garnet MXene composite material is obtained.

[0040] It should be noted that in the present invention, various rare-earth oxides and Fe2O3 are used as raw materials, and through ball milling treatment, the components are uniformly dispersed at the atomic scale; during the high-temperature sintering process, solid-state reactions occur among the components to form high-entropy ceramic powders with a garnet structure. Subsequently, the surface of the ceramics is modified with a PDDA solution to endow it with abundant functional functional groups, which is conducive to the interfacial composite with single-layer MXene. This composite process helps to construct a composite material with a tightly bonded interface and excellent wave-absorbing performance.

[0041] Example 1

[0042] Weigh the oxide raw materials Er2O3, Sm2O3, Gd2O3, Nd2O3, Eu2O3 and Fe2O3 in appropriate molar ratios (x:y:z:m:n = 0.3:0.7:0.5:0.6:0.4), and add them to a ball milling jar. The volume ratio of ethanol to water in the ball milling jar is 1:1. Subsequently, carry out ball milling treatment at a rotation speed of 200 rpm for 3 h to ensure that the powders are fully mixed. After the ball milling is completed, transfer the mixed powders to an oven for drying treatment; transfer the dried powders to a crucible and place it in a muffle furnace. During the heating-up stage, raise the temperature to 1200 °C at a rate of 1 °C / min, and keep it at this temperature for 3 h for high-temperature sintering. Then, cool it to 600 °C at a rate of 1 °C / min and then cool it naturally. Prepare an aqueous PDDA solution with a volume ratio of PDDA to water of 1:2000. Modify the surface of the obtained high-entropy ceramics with the aqueous PDDA solution: suck 1 ml of the single-layer MXene solution and add it to the aqueous solution of the modified high-entropy ceramics and stir at a stirring speed of 300 rpm for 0.5 h. Finally, centrifuge and collect the reactants, and then dry them in vacuum for 4 h and store them after drying.

[0043] Example 2

[0044] Weigh the oxide raw materials Er2O3, Sm2O3, Gd2O3, Nd2O3, Eu2O3 and Fe2O3 in appropriate molar ratios (x:y:z:m:n = 0.8:0.2:0.6:0.4:0.5), and add them to a ball milling jar. The volume ratio of ethanol to water in the ball milling jar is 1:1. Subsequently, carry out ball milling treatment at a speed of 400 rpm for 5 h to ensure that the powders are fully mixed. After ball milling is completed, transfer the mixed powders to an oven for drying treatment; transfer the dried powders to a crucible, place it in a muffle furnace, and raise the temperature to 1300 °C at a rate of 3 °C / min during the heating stage, and keep it at this temperature for 4 h for high-temperature sintering, and then cool it to 650 °C at a rate of 3 °C / min and then cool it naturally. Prepare an aqueous PDDA solution with a volume ratio of PDDA to water of 2:2000. Carry out surface modification on the obtained high-entropy ceramic with the aqueous PDDA solution: suck 3 ml of monolayer MXene solution, add it to the aqueous solution of the modified high-entropy ceramic and stir at a stirring speed of 400 rpm for 1 h. Finally, centrifuge and collect the reactants, and dry them in vacuum for 6 h and then store them after drying.

[0045] Example 3

[0046] Weigh the oxide raw materials Er2O3, Sm2O3, Gd2O3, Nd2O3, Eu2O3 and Fe2O3 in appropriate molar ratios (x:y:z:m:n = 0.5:0.3:0.7:0.6:0.2), and add them to a ball milling jar. The volume ratio of ethanol to water in the ball milling jar is 1:1. Subsequently, carry out ball milling treatment at a speed of 600 rpm for 8 h to ensure that the powders are fully mixed. After ball milling is completed, transfer the mixed powders to an oven for drying treatment; transfer the dried powders to a crucible, place it in a muffle furnace, and raise the temperature to 1400 °C at a rate of 5 °C / min during the heating stage, and keep it at this temperature for 5 h for high-temperature sintering, and then cool it to 700 °C at a rate of 5 °C / min and then cool it naturally. Prepare an aqueous PDDA solution with a volume ratio of PDDA to water of 3:2000. Carry out surface modification on the obtained high-entropy ceramic with the aqueous PDDA solution: suck 5 ml of monolayer MXene solution, add it to the aqueous solution of the modified high-entropy ceramic and stir at a stirring speed of 600 rpm for 2 h. Finally, centrifuge and collect the reactants, and dry them in vacuum for 8 h and then store them after drying.

[0047] Example 4

[0048] Weigh the oxide raw materials Er2O3, Sm2O3, Gd2O3, Nd2O3, Eu2O3 and Fe2O3 in appropriate molar ratios (x:y:z:m:n = 0.4:0.5:0.8:0.3:0.6), and add them to a ball milling jar. The volume ratio of ethanol to water in the ball milling jar is 1:1. Subsequently, carry out ball milling treatment at a speed of 250 rpm for 4 h to ensure that the powders are fully mixed. After ball milling is completed, transfer the mixed powder to an oven for drying treatment; transfer the dried powder to a crucible, place it in a muffle furnace, and raise the temperature to 1250 °C at a rate of 2 °C / min during the heating stage, and hold at this temperature for 3.5 h for high-temperature sintering, and then cool down to 650 °C at a rate of 2 °C / min and then cool naturally. Prepare an aqueous PDDA solution with a volume ratio of PDDA to water of 2:2000. Carry out surface modification of the obtained high-entropy ceramic with the aqueous PDDA solution: suck 2 ml of monolayer MXene solution, add it to the modified high-entropy ceramic aqueous solution and stir, with a stirring speed of 350 rpm and a stirring time of 1.5 h. Finally, centrifuge and collect the reactants, and dry them in vacuum for 5 h and then store them dry.

[0049] Example Five

[0050] Weigh the oxide raw materials Er2O3, Sm2O3, Gd2O3, Nd2O3, Eu2O3 and Fe2O3 in appropriate molar ratios (x:y:z:m:n = 0.7:0.6:0.4:0.5:0.3), and add them to a ball milling jar. The volume ratio of ethanol to water in the ball milling jar is 1:1. Subsequently, carry out ball milling treatment at a speed of 800 rpm for 7 h to ensure that the powders are fully mixed. After ball milling is completed, transfer the mixed powder to an oven for drying treatment; transfer the dried powder to a crucible, place it in a muffle furnace, and raise the temperature to 1350 °C at a rate of 4 °C / min during the heating stage, and hold at this temperature for 4.5 h for high-temperature sintering, and then cool down to 700 °C at a rate of 4 °C / min and then cool naturally. Prepare an aqueous PDDA solution with a volume ratio of PDDA to water of 1:2000. Carry out surface modification of the obtained high-entropy ceramic with the aqueous PDDA solution: suck 4 ml of monolayer MXene solution, add it to the modified high-entropy ceramic aqueous solution and stir, with a stirring speed of 500 rpm and a stirring time of 1 h. Finally, centrifuge and collect the reactants, and dry them in vacuum for 7 h and then store them dry.

[0051] In summary, the present invention uses rare earth oxides and iron oxides as raw materials, and through high-temperature sintering, multiple metal elements are evenly distributed in the garnet structure to form a ceramic material with high entropy stability. It has a high specific surface area of multiple metal element combinations and good electromagnetic wave isolation characteristics, which can significantly enhance the wave absorption treatment effect and has application potential in the fields of electromagnetic shielding and radar stealth.

[0052] It should be emphasized that the above are only the preferred embodiments of the present invention, and there is no limitation in any form to the present invention. Any simple modification, equivalent change and modification made to the above embodiments based on the technical essence of the present invention still fall within the scope of the technical solution of the present invention.

Claims

1. A high-entropy rare-earth Fe-based garnet composite MXene material, characterized in that, The general formula of the high-entropy rare-earth Fe-based garnet composite MXene material is: (Er x Gd y Eu z Sm m Nd n )3Fe5O 12 @MXene; where the value ranges of x, y, z, m, and n are 0.1 to 0.9, respectively.

2. The high-entropy rare-earth Fe-based garnet composite MXene material according to claim 1, wherein The high-entropy rare-earth Fe-based garnet composite MXene material is a solid solution formed by rare-earth elements Er, Gd, Eu, Sm, and Nd in the Fe-based garnet structure, with the characteristics of high-entropy ceramics; in the high-entropy rare-earth Fe-based garnet composite MXene material, rare-earth ions are completely solid-solved in the garnet lattice to form a homogeneous high-entropy solid solution, and the composite MXene material further improves the wave-absorbing performance.

3. The high-entropy rare-earth Fe-based garnet composite MXene material according to claim 1, wherein The value ranges of x, y, z, m, and n are 0.3 to 0.7 respectively.

4. A preparation method of a high-entropy rare-earth Fe-based garnet composite MXene material, characterized in that, The preparation method is used to prepare the high-entropy rare-earth Fe-based garnet composite MXene material described in any one of claims 1 to 3; the preparation method includes the following steps: Step 1: Weigh the rare-earth oxide raw materials according to the ratio, and perform ball milling treatment to fully mix the raw materials to obtain a mixed powder; Step 2: After the ball milling is completed, dry the mixed powder obtained in Step 1; Step 3: Perform high-temperature sintering on the dried mixed powder in Step 2, cool down after high-temperature sintering, and obtain high-entropy ceramic powder; Step 4: Surface-modify the high-entropy ceramic powder obtained in Step 3 with PDDA solution, mix it with monolayer MXene, and collect it to finally obtain the high-entropy ceramic material.

5. The preparation method of a high-entropy rare-earth Fe-based garnet composite MXene material according to claim 4, characterized in that, In Step 1, the rare-earth oxides include: Er2O3, Sm2O3, Gd2O3, Nd2O3, Eu2O3, and Fe2O3; the ratio in the proportional weighing is the molar ratio.

6. The preparation method of a high-entropy rare-earth Fe-based garnet composite MXene material according to claim 4, characterized in that, In Step 1, the co-permeation medium for the ball milling treatment includes: ethanol and water; the volume ratio of ethanol to water in the co-permeation medium is 1:0.8 to 1.

2.

7. The preparation method of a high-entropy rare-earth Fe-based garnet composite MXene material according to claim 4, characterized in that, In Step 1, during the ball milling treatment, the rotation speed of the ball milling machine is 200 to 800 rmp, and the mixing time of the raw materials by ball milling is 3 to 8 hours.

8. The preparation method of a high-entropy rare-earth Fe-based garnet composite MXene material according to claim 7, characterized in that, In Step 3, during the high-temperature sintering, the temperature is raised to 1200 to 1400 °C at a heating rate of 1 to 5 °C / min in the heating stage, and held at this temperature for 3 to 5 hours; during the cooling, the temperature is cooled down to 600 to 700 °C at a cooling rate of 1 to 5 °C / min and then naturally cooled.

9. The preparation method of a high-entropy rare-earth Fe-based garnet composite MXene material according to claim 4, characterized in that, In Step 4, the PDDA solution is prepared from an aqueous solution, and the volume ratio of PDDA to water is: (1 to 3):2000; The dosage ratio of the monolayer MXene to the high-entropy ceramic is: 1 to 5 ml:1 mg; The dosage ratio of the PDDA solution to the high-entropy ceramic is: 1 ml:1 to 5 mg.

10. The preparation method of a high-entropy rare-earth Fe-based garnet composite MXene material according to claim 4, characterized in that, In Step 4, when the high-entropy ceramic is compounded with MXene, the stirring speed is 300 to 600 rpm, and the stirring time is 0.5 to 2 hours.

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