Layered high-entropy MBene material, preparation method and application thereof

Abstract

This invention belongs to the field of electromagnetic absorbing materials technology. It relates to a layered high-entropy MBene material, its preparation method, and its applications. This invention utilizes high-temperature Joule heating to prepare the layered high-entropy MBene material. This layered high-entropy MBene material possesses many significant advantages, such as abundant defect density, good conductivity loss, high specific surface area, a large number of exposed surface atoms, and excellent mechanical and electronic properties. It can effectively control electromagnetic parameters and achieve excellent electromagnetic absorption performance. Furthermore, it exhibits nanoscale effects, which can induce lattice distortion, defects, and microstrain, significantly optimizing impedance matching and enhancing dipole polarization and conductivity loss, thus demonstrating outstanding microwave absorption performance. The high-temperature Joule heating synthesis strategy proposed in this invention provides a new approach for the development of advanced high-entropy electromagnetic absorbing materials and offers a general method for the development of other layered materials with tunable structures.

Description

Technical Field

[0001] This invention belongs to the field of electromagnetic wave absorbing materials technology, and specifically relates to a layered high-entropy MBene material, its preparation method, and its application. Background Technology

[0002] The widespread adoption of radio electromagnetic wave communication technology and electronic devices has significantly improved the quality of human life, but it has also inevitably brought about environmental problems such as electromagnetic radiation pollution and electromagnetic interference. These phenomena not only pose potential hazards to human health but also threaten the secure operation of critical information systems. In response to this situation, the development of novel electromagnetic wave absorbing materials with comprehensive performance indicators of "thinness, lightness, wide coverage, and strength" is considered the most promising solution. In the design process of absorbing materials, multi-scale structural control plays a crucial role, encompassing micrometer-scale heterostructure construction, nanometer-scale multiphase structure design, and atomic-level lattice defect control. Although significant progress has been made in micro- and nano-scale structural design, exploration in the innovative field of atomic-scale defect engineering remains insufficient. It is worth noting that the unique severe lattice distortion effect in high-entropy ceramic materials can induce a rich variety of atomic-scale defects. This characteristic opens up a new research path for developing high-performance single-phase absorbing materials through precise control of lattice distortion.

[0003] In recent years, two-dimensional transition metal borides (MBene) have emerged as a novel class of two-dimensional materials. Their metallic conductivity and excellent mechanical, optical, and electronic properties have garnered significant attention in optoelectronic devices, catalysis, and energy fields. Furthermore, due to their high composite dielectric constant, MBene is a dielectric material with excellent electrical storage and dissipation capabilities, and is considered a promising electromagnetic absorption material. Combining different two-dimensional materials can provide numerous interfaces conducive to electromagnetic wave absorption. High-entropy materials (HEMs), due to their diverse compositions and unexpected physicochemical properties, possess great potential for energy storage and conversion. However, high-entropy atomic layers with fully exposed active sites are difficult to synthesize due to their tendency to phase segregate. Therefore, this invention proposes a novel strategy for preparing high-entropy materials. Summary of the Invention

[0004] To address the shortcomings of the existing technologies, the present invention aims to provide a layered high-entropy MBene material, its preparation method, and its applications. This invention solves the problem that preparing high-entropy atomic layers with fully exposed active sites is difficult due to easy phase separation. The present invention utilizes a high-temperature Joule heating method to prepare layered high-entropy MBene material in one step. This layered high-entropy MBene material exhibits excellent microwave absorption performance, with a minimum reflection loss of -48.2 dB (2.50 mm) and an effective absorption bandwidth of 4.8 GHz, surpassing the performance of traditional MAX phases and most commercial materials.

[0005] To address the aforementioned technical problems, this invention provides a method for preparing layered high-entropy MBene materials, comprising the following steps: A mixture is prepared by mixing transition metal oxides with amorphous B4C powder. The mixture is then pressed into a block under a pressure of 5 MPa to 20 MPa to obtain a sample. The sample was subjected to high-temperature Joule heating at 1500℃~2500℃ under an argon atmosphere. After heating for 20s~40s, it was naturally cooled to room temperature and the MBene precursor powder was obtained. The MBene precursor powder was ground and sieved to obtain layered high-entropy MBene material, wherein the mass of amorphous B4C powder was 1.1 to 1.5 times the total mass of transition metal oxides. The transition metal oxides were at least five of the following: HfO2, Ta2O5, Nb2O5, ZrO2, TiO2, V2O5, MoO3, WO3, Cr2O3, Fe2O3, or Co2O3, and the various metal oxides were weighed according to the equimolar ratio of metal atoms.

[0006] Preferably, the purity of both the amorphous B4C powder and the transition metal oxide is 99.5%~99.9%, the particle size of the amorphous B4C powder is 100 mesh~200 mesh, and the particle size of the transition metal oxide is 200 mesh~300 mesh.

[0007] Preferably, the heating rate of the high-temperature Joule heating is 50 K s. -1 ~100K s -1 .

[0008] Preferably, the heating rate of the high-temperature Joule heating is 50 K s. -1 ~80K s -1 .

[0009] Preferably, the grinding time of the MBene precursor powder is 30 min to 60 min, and the sieve mesh size is 200 mesh to 300 mesh.

[0010] The layered high-entropy MBene material prepared by the method provided in this invention yields a layered high-entropy MBene material.

[0011] This invention presents the application of layered high-entropy MBene materials in 5G / 6G base stations, EMC protection of electronic devices, high-end transportation equipment, and integrated stealth and thermal protection for aircraft.

[0012] Preferably, the layered high-entropy MBene material and paraffin are weighed at a weight ratio of 1~8:2~9, mixed uniformly at 70°C for 30 minutes, and after natural cooling, the sample is processed into a central ring with an inner diameter of 3.04 mm, an outer diameter of 7.00 mm, and a thickness of 3 mm.

[0013] Compared with the prior art, the beneficial effects of the present invention are as follows: The method for preparing layered high-entropy MBene materials provided in this invention uses transition metal oxides and amorphous B4C powder as raw materials. Layered high-entropy MBene materials are prepared in one step by Joule heating under an argon atmosphere. At a Joule heating temperature of 1500℃~2500℃, amorphous B4C powder is not only a boron source but also a strong reducing agent. The carbon and boron in amorphous B4C react with oxygen in transition metal oxides to generate metal borides and CO gas or metal borides and CO2 gas. This one-step Joule heating method directly reduces the metal in the transition metal oxide from a high-valence oxide state and carbonizes / borides into the target boride phase, skipping the step of first synthesizing the metal element or intermediate alloy, thus reducing the reaction steps. Furthermore, since this method utilizes Joule heating, it boasts an extremely high heating rate, rapidly raising the reaction system to the reaction temperature. This suppresses potential side reactions or phase separation that might occur in the low and medium temperature ranges during the reaction, forcing the reaction to proceed rapidly in the thermodynamically most favorable high-temperature region, which is conducive to the formation of metastable or high-entropy phases. Simultaneously, the short reaction time of the Joule heating method also limits excessive grain growth. After the atoms have fully diffused and mixed to form the high-entropy phase, rapid cooling can freeze this high-entropy state and layered morphology, preventing elemental segregation, phase decomposition, or grain coarsening at prolonged high temperatures, thus facilitating the acquisition of nanoscale / submicron-scale layered structures. This preparation method also provides the necessary thermodynamic conditions for the formation of high-entropy alloys. The extremely fast atomic diffusion rate at high temperatures allows metal atoms from five or more different transition metal oxides to overcome diffusion barriers and achieve uniform mixing in the boride lattice, thereby forming a single-phase solid solution, i.e., generating high-entropy borides. This layered high-entropy MBene material exhibits excellent microwave absorption performance, with a minimum reflection loss of -48.2dB (2.50mm) and an effective absorption bandwidth of 4.8GHz, surpassing the performance of traditional MAX phase and most commercial materials.

[0014] The layered high-entropy MBene material prepared in this invention possesses many significant advantages, such as abundant defect density, good conductivity loss, high specific surface area, a large number of exposed surface atoms, and excellent mechanical and electronic properties. It can effectively control electromagnetic parameters and achieve superior electromagnetic absorption performance. Simultaneously, this layered high-entropy MBene material exhibits a nanoscale effect, which can simultaneously induce lattice distortion, defects, and microstrain, significantly optimizing impedance matching and enhancing dipole polarization and conductivity loss, thus demonstrating outstanding microwave absorption performance. Furthermore, thanks to the high-entropy structural effect of the layered high-entropy MBene material, it achieves excellent electromagnetic properties, making it a promising candidate for electromagnetic protection applications and expanding its application boundaries. It can be widely used in 5G / 6G base stations, EMC protection of electronic equipment, high-end transportation equipment, and integrated stealth and thermal protection for aircraft. Attached Figure Description

[0015] Figure 1 The image shows the SEM morphology of the layered high-entropy MBene material prepared in Example 1 of this invention.

[0016] Figure 2 The image shows the XRD pattern of the layered high-entropy MBene material prepared in Example 1 of this invention.

[0017] Figure 3 The image shows the EPR test results of the layered high-entropy MBene material prepared in Example 1 of this invention.

[0018] Figure 4 The electromagnetic absorption performance diagram of the layered high-entropy MBene material prepared in Example 1 of the present invention is shown. Detailed Implementation

[0019] The specific embodiments of the present invention are described in detail below, but it should be understood that the scope of protection of the present invention is not limited to the specific embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention. Unless otherwise specified, the experimental methods described in the embodiments of the present invention are conventional methods.

[0020] It should be noted that when numerical ranges are involved in this invention, it should be understood that the two endpoints of each numerical range and any value between the two endpoints can be selected. Since the steps and methods used are the same as in Examples 1 to 10, preferred embodiments are described in this invention to avoid redundancy. However, this invention is not limited to these, but can be implemented in other ways within the scope of the technical solutions defined in the appended claims. All raw materials, reagents, instruments, and equipment used in the following embodiments of this invention can be purchased from the market or prepared by existing methods.

[0021] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention, the preferred embodiments, and the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0022] Example 1 A method for preparing a layered high-entropy MBene material includes the following steps: A mixture was prepared by mixing transition metal oxides HfO2, Ta2O5, Nb2O5, ZrO2, TiO2, V2O5, MoO3, WO3, Cr2O3, Fe2O3, and Co2O3 with a purity of 99.9% and a particle size of 300 mesh with amorphous B4C powder with a purity of 99.9% and a particle size of 100 mesh. The mass of the amorphous B4C powder was 1.3 times the total mass of the transition metal oxides. The mixture was pressed into a block with a size of 16 mm × 16 mm × 5 mm and held under a pressure of 10 MPa for 3 min to obtain a sample. The sample was placed in a Joule furnace under an argon atmosphere and heated at 80 K s. -1 The temperature was increased from room temperature to 2000℃ at a heating rate of 0.5, and then held at 2000℃ for 30 seconds under high-temperature Joule heating. After natural cooling to room temperature, the MBene precursor powder was obtained. The MBene precursor powder was then ground for 30 minutes and sieved through a 300-mesh sieve to obtain layered high-entropy MBene material.

[0023] Example 2 A method for preparing a layered high-entropy MBene material includes the following steps: A mixture was prepared by mixing transition metal oxides HfO2, Ta2O5, Nb2O5, ZrO2, TiO2, V2O5, MoO3, WO3, Cr2O3, Fe2O3, and Co2O3 with a purity of 99.9% and a particle size of 200 mesh with amorphous B4C powder with a purity of 99.99% and a particle size of 150 mesh. The mass of the amorphous B4C powder was 1.1 times the total mass of the transition metal oxides. The mixture was pressed into a block with a size of 16 mm × 16 mm × 5 mm and held at a pressure of 5 MPa for 3 min to obtain a sample. The sample was placed in a Joule furnace under an argon atmosphere and heated at 50 K s. -1The temperature was increased from room temperature to 1500℃ at a heating rate of 1500℃, and then held at 1500℃ for 20 seconds. After natural cooling to room temperature, the MBene precursor powder was obtained. The MBene precursor powder was then ground for 60 minutes and sieved through a 200-mesh sieve to obtain layered high-entropy MBene material.

[0024] Example 3 A method for preparing a layered high-entropy MBene material includes the following steps: A mixture was prepared by mixing transition metal oxides HfO2, Ta2O5, Nb2O5, ZrO2, TiO2, V2O5, MoO3, WO3, Cr2O3, Fe2O3, and Co2O3 with a purity of 99.6% and a particle size of 250 mesh with amorphous B4C powder with a purity of 99.6% and a particle size of 150 mesh. The mass of the amorphous B4C powder was 1.5 times the total mass of the transition metal oxides. The mixture was pressed into a block with a size of 16 mm × 16 mm × 5 mm and held under a pressure of 20 MPa for 3 min to obtain a sample. The sample was placed in a Joule furnace under an argon atmosphere and heated at 100 K s. -1 The temperature was increased from room temperature to 2500℃ at a heating rate of 0.5%, and then held at 2500℃ for 40 seconds under high-temperature Joule heating. After natural cooling to room temperature, the MBene precursor powder was obtained. The MBene precursor powder was then ground for 50 minutes and sieved through a 250-mesh sieve to obtain layered high-entropy MBene material.

[0025] Example 4 A method for preparing a layered high-entropy MBene material includes the following steps: A mixture was prepared by mixing transition metal oxides HfO2, Ta2O5, Nb2O5, ZrO2, and TiO2 with a purity of 99.9% and a particle size of 300 mesh with amorphous B4C powder with a purity of 99.9% and a particle size of 100 mesh, wherein the mass of amorphous B4C powder was 1.3 times the total mass of the transition metal oxides; the mixture was pressed into a block with a size of 16 mm × 16 mm × 5 mm and held under a pressure of 10 MPa for 3 min to obtain a sample; The sample was placed in a Joule furnace under an argon atmosphere and heated at 80 K s. -1 The temperature was increased from room temperature to 2000℃ at a heating rate of 0.5, and then held at 2000℃ for 30 seconds under high-temperature Joule heating. After natural cooling to room temperature, the MBene precursor powder was obtained. The MBene precursor powder was then ground for 30 minutes and sieved through a 300-mesh sieve to obtain layered high-entropy MBene material.

[0026] Example 5 A method for preparing a layered high-entropy MBene material includes the following steps: A mixture was prepared by mixing transition metal oxides HfO2, Ta2O5, Nb2O5, V2O5, MoO3, WO3, Cr2O3, Fe2O3, and Co2O3 with a purity of 99.9% and a particle size of 300 mesh with amorphous B4C powder with a purity of 99.9% and a particle size of 100 mesh. The mass of the amorphous B4C powder was 1.3 times the total mass of the transition metal oxides. The mixture was pressed into a block with a size of 16 mm × 16 mm × 5 mm and held under a pressure of 10 MPa for 3 min to obtain a sample. The sample was placed in a Joule furnace under an argon atmosphere and heated at 80 K s. -1 The temperature was increased from room temperature to 2000℃ at a heating rate of 0.5, and then held at 2000℃ for 30 seconds under high-temperature Joule heating. After natural cooling to room temperature, the MBene precursor powder was obtained. The MBene precursor powder was then ground for 30 minutes and sieved through a 300-mesh sieve to obtain layered high-entropy MBene material.

[0027] Example 6 A method for preparing a layered high-entropy MBene material includes the following steps: A mixture was prepared by mixing transition metal oxides HfO2, Ta2O5, Nb2O5, ZrO2, TiO2, V2O5, MoO3, WO3, Cr2O3, and Co2O3 with a purity of 99.9% and a particle size of 300 mesh with amorphous B4C powder with a purity of 99.9% and a particle size of 100 mesh. The mass of the amorphous B4C powder was 1.3 times the total mass of the transition metal oxides. The mixture was pressed into a block with a size of 16 mm × 16 mm × 5 mm and held under a pressure of 10 MPa for 3 min to obtain a sample. The sample was placed in a Joule furnace under an argon atmosphere and heated at 80 K s. -1 The temperature was increased from room temperature to 2000℃ at a heating rate of 0.5, and then held at 2000℃ for 30 seconds under high-temperature Joule heating. After natural cooling to room temperature, the MBene precursor powder was obtained. The MBene precursor powder was then ground for 30 minutes and sieved through a 300-mesh sieve to obtain layered high-entropy MBene material.

[0028] Example 7 A method for preparing a layered high-entropy MBene material includes the following steps: A mixture was prepared by mixing transition metal oxides V2O5, MoO3, WO3, Cr2O3 and Co2O3 with a purity of 99.9% and a particle size of 300 mesh with amorphous B4C powder with a purity of 99.9% and a particle size of 100 mesh, wherein the mass of amorphous B4C powder was 1.3 times the total mass of transition metal oxides. The mixture was pressed into a block with dimensions of 16mm × 16mm × 5mm and held under a pressure of 10MPa for 3 minutes to obtain a sample. The sample was placed in a Joule furnace under an argon atmosphere and heated at 80 K s. -1 The temperature was increased from room temperature to 2000℃ at a heating rate of 0.5, and then held at 2000℃ for 30 seconds under high-temperature Joule heating. After natural cooling to room temperature, the MBene precursor powder was obtained. The MBene precursor powder was then ground for 30 minutes and sieved through a 300-mesh sieve to obtain layered high-entropy MBene material.

[0029] Example 8 A method for preparing a layered high-entropy MBene material includes the following steps: Transition metal oxides with a purity of 99.9% and a particle size of 300 mesh, namely ZrO2, TiO2, V2O5, MoO3, WO3, and Cr2O3, were mixed with amorphous B4C powder with a purity of 99.9% and a particle size of 100 mesh to obtain a mixture, wherein the mass of amorphous B4C powder was 1.3 times the total mass of the transition metal oxides; the mixture was pressed into a block with a size of 16mm × 16mm × 5mm and held under a pressure of 10MPa for 3min to obtain a sample; The sample was placed in a Joule furnace under an argon atmosphere and heated at 80 K s. -1 The temperature was increased from room temperature to 2000℃ at a heating rate of 0.5, and then held at 2000℃ for 30 seconds under high-temperature Joule heating. After natural cooling to room temperature, the MBene precursor powder was obtained. The MBene precursor powder was then ground for 30 minutes and sieved through a 300-mesh sieve to obtain layered high-entropy MBene material.

[0030] Example 9 A method for preparing a layered high-entropy MBene material includes the following steps: A mixture was prepared by mixing transition metal oxides HfO2, Ta2O5, Nb2O5, ZrO2, TiO2, V2O5, and MoO3 with a purity of 99.9% and a particle size of 300 mesh with amorphous B4C powder with a purity of 99.9% and a particle size of 100 mesh. The mass of the amorphous B4C powder was 1.3 times the total mass of the transition metal oxides. The mixture was pressed into a block with a size of 16 mm × 16 mm × 5 mm and held under a pressure of 10 MPa for 3 min to obtain a sample. The sample was placed in a Joule furnace under an argon atmosphere and heated at 80 K s. -1 The temperature was increased from room temperature to 2000℃ at a heating rate of 0.5, and then held at 2000℃ for 30 seconds under high-temperature Joule heating. After natural cooling to room temperature, the MBene precursor powder was obtained. The MBene precursor powder was then ground for 30 minutes and sieved through a 300-mesh sieve to obtain layered high-entropy MBene material.

[0031] Example 10 A method for preparing a layered high-entropy MBene material includes the following steps: A mixture was prepared by mixing transition metal oxides HfO2, Ta2O5, Nb2O5, ZrO2, Cr2O3, and Co2O3 with a purity of 99.9% and a particle size of 300 mesh with amorphous B4C powder with a purity of 99.9% and a particle size of 100 mesh. The mass of the amorphous B4C powder was 1.3 times the total mass of the transition metal oxides. The mixture was pressed into a block with a size of 16 mm × 16 mm × 5 mm and held under a pressure of 10 MPa for 3 min to obtain a sample. The sample was placed in a Joule furnace under an argon atmosphere and heated at 80 K s. -1 The temperature was increased from room temperature to 2000℃ at a heating rate of 0.5, and then held at 2000℃ for 30 seconds under high-temperature Joule heating. After natural cooling to room temperature, the MBene precursor powder was obtained. The MBene precursor powder was then ground for 30 minutes and sieved through a 300-mesh sieve to obtain layered high-entropy MBene material.

[0032] Layered high-entropy MBene materials can be prepared using Examples 1 to 10. The layered high-entropy MBene materials prepared in Examples 1 and 2 are preferred for efficacy verification.

[0033] Experimental verification (a) Structural confirmation (1) SEM Figure 1 This is a SEM morphology image of the layered high-entropy MBene material prepared in Example 1 of this invention. Figure 1 It can be seen that there is a distinct two-dimensional layered structure.

[0034] (2) XRD Figure 2 The image shows the XRD pattern of the layered high-entropy MBene material prepared in Example 1 of this invention. Figure 2 It can be seen that the obtained material has a relatively stable crystal form and exhibits a polycrystalline structure.

[0035] (0) Performance Analysis (1) EPR test Figure 3 The EPR test image of the layered high-entropy MBene material prepared in Example 1 of this invention is obtained through... Figure 3 It can be seen that the EPR curve shows a clear signal peak, indicating that the material has abundant oxygen vacancy defects.

[0036] (2) Electromagnetic absorption performance The layered high-entropy MBene material obtained in Example 1 was weighed with paraffin at a ratio of 1~8:2~9. Preferably, the layered high-entropy MBene material was weighed with paraffin at a weight ratio of 3:7. The mixture was then uniformly mixed at 70°C for 30 minutes and allowed to cool naturally. The sample was then processed into a central ring with an inner diameter of 3.04 mm, an outer diameter of 7.00 mm, and thicknesses of 1 mm, 1.5 mm, 2.0 mm, 2.5 mm, 3 mm, 3.5 mm, and 4 mm. The electromagnetic absorption performance of the central rings with different thicknesses was then tested. Figure 4 The electromagnetic absorption performance diagram of the layered high-entropy MBene material prepared in Example 1 of the present invention is shown below. Figure 4 It is known that the strongest absorption reaches -48.2dB and the effective absorption bandwidth is 4.8GHz, making it an electromagnetic absorption material with excellent performance.

[0037] Obviously, those skilled in the art can make various modifications and variations to this invention without departing from its spirit and scope. Therefore, if these modifications and variations fall within the scope of the claims of this invention and their equivalents, this invention also intends to include these modifications and variations.

Claims

1. A method for preparing a layered high-entropy MBene material, characterized in that, Includes the following steps: A mixture of transition metal oxide and amorphous B4C powder was obtained, and the mixture was pressed into a block under a pressure of 5 MPa to 20 MPa to obtain a sample. The sample was subjected to high-temperature Joule heating at 1500℃~2500℃ under an argon atmosphere. After heating for 20s~40s, it was naturally cooled to room temperature and the MBene precursor powder was obtained. The MBene precursor powder was ground and sieved to obtain layered high-entropy MBene material, wherein the mass of amorphous B4C powder was 1.1 to 1.5 times the total mass of transition metal oxides. The transition metal oxides were at least five of the following: HfO2, Ta2O5, Nb2O5, ZrO2, TiO2, V2O5, MoO3, WO3, Cr2O3, Fe2O3, or Co2O3, and the various metal oxides were weighed according to the equimolar ratio of metal atoms.

2. The method for preparing layered high-entropy MBene material according to claim 1, characterized in that, The purity of both the amorphous B4C powder and the transition metal oxide is 99.5%~99.9%, the particle size of the amorphous B4C powder is 100 mesh~200 mesh, and the particle size of the transition metal oxide is 200 mesh~300 mesh.

3. The method for preparing layered high-entropy MBene material according to claim 1, characterized in that, The heating rate of the high-temperature Joule heating is 50 K s. -1 ~100K s -1 .

4. The method for preparing layered high-entropy MBene material according to claim 3, characterized in that, The heating rate of the high-temperature Joule heating is 50 K s. -1 ~80K s -1 .

5. The method for preparing layered high-entropy MBene material according to claim 1, characterized in that, The grinding time for MBene precursor powder is 30 min to 60 min, and the sieve mesh size is 200 mesh to 300 mesh.

6. The layered high-entropy MBene material prepared by the preparation method according to any one of claims 1 to 5.

7. The application of the layered high-entropy MBene material according to claim 6 in 5G / 6G base stations, EMC protection of electronic devices, high-end transportation equipment, and integrated stealth and thermal protection of aircraft.

8. The application according to claim 8, characterized in that, The layered high-entropy MBene material and paraffin were weighed at a weight ratio of 1~8:2~9, and then mixed uniformly at 70℃ for 30 minutes. After natural cooling, the sample was processed into a central ring with an inner diameter of 3.04 mm, an outer diameter of 7.00 mm, and a thickness of 3 mm.

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