High-entropy garnet-based ceramic solidified body and method for manufacturing the same

Abstract

The application discloses a high-entropy garnet-based ceramic solidification body, which has a chemical formula of Y 0.6 Gd 0.6 Sm 0.6 Eu 0.6 Dy 0.6 Fe5O 12 , and a crystal grain size of 0.50-0.75 mu m and a compactness of more than 99%. A preparation method of the high-entropy garnet-based ceramic solidification body comprises the following steps: mixing oxide powders, ball milling, drying, sintering by using a discharge plasma sintering furnace, and annealing, so as to obtain the high-entropy garnet-based ceramic solidification body. Four kinds of simulated nuclides are successfully solid-solved into the high-entropy garnet, and the high-entropy garnet-based ceramic solidification body Y 0.6 Gd 0.6 Sm 0.6 Eu 0.6 Dy 0.6 Fe5O 12 is prepared, and the simultaneous solidification of multiple nuclides of different types is realized. The high-entropy garnet-based ceramic solidification body prepared by the application has fine and uniform crystal grains, high compactness, excellent chemical stability, and low nuclide leaching rate. In addition, the sintering of the application adopts the discharge plasma sintering furnace, so that the high-entropy garnet-based ceramic solidification body can be prepared at low temperature and quickly, and the problems of high sintering temperature and long sintering time required by the traditional solid-phase sintering method are avoided, and the production cost is reduced.

Description

Technical Field

[0001] The present invention belongs to the technical field of ceramic solid bodies, and more specifically, relates to a high-entropy garnet-based ceramic solid body and a preparation method thereof. Background Art

[0002] The application of nuclear fission technology will inevitably produce high-level radioactive waste, which will release α, β and γ unstable elements and pose a serious threat to the ecological environment. 12 Garnet is a promising element-immobilization matrix due to its multiple sites, topological structure, and good chemical tolerance. In the context of high-level radioactive waste (HLW), traditional garnet-based solidifiers often target only a single nuclide. However, real HLW contains a wide variety of actinides. Therefore, the development of a ceramic solidifier that can immobilize multiple nuclides and exhibits excellent chemical stability is highly desirable.

[0003] High-entropy ceramics are a new type of ceramic that has recently emerged, enriching the ceramic system. In the late 1990s, Professor Ye Junwei of National Tsing Hua University in Taiwan proposed the concept of high entropy, defining it as a material with ≥5 elements, no dominant element, and a total element content between 5% and 35%. High-entropy ceramic powders can be sintered to form stable single-phase solid solutions with advantages such as high thermal conductivity, high melting point, good corrosion resistance, excellent biocompatibility, and excellent electrochemical properties. High-entropy ceramics have great potential for development in ultrahigh temperature, biomedical, and energy fields. However, limited research has been conducted on combining high entropy with yttrium iron garnet (YIG).

[0004] The existing technology usually uses the traditional solid-phase method to sinter garnet. This method has high calcination temperature, long time and high energy consumption, which limits its large-scale production. For example, patent CN116514536A discloses a high-entropy YIG ferrite with high saturation magnetization and its preparation method, which adopts the method of ball milling, pre-calcination, secondary ball milling, granulation and sintering. The calcination temperature reaches 1400°C and the two calcination times reach 8 hours. The whole process is long and easy to mix during the process. It is difficult to obtain a high-purity powder, which will ultimately affect the performance of the material; patent CN116605915A discloses a high-entropy ceramic with a garnet structure and its preparation method and application. It adopts the method of ball milling, pre-calcination and sintering. The sintering temperature reaches 1350°C and the two calcination times reach 22 hours. The application of low-temperature rapid sintering technology in the field of ceramic solid bodies is particularly important. Therefore, it is of great significance to develop a method for preparing high-entropy garnet-based ceramic solid bodies at low temperature and quickly. Summary of the Invention

[0005] An object of the present invention is to solve at least the above problems and / or disadvantages and to provide at least the advantages which will be described hereinafter.

[0006] In order to achieve these objects and other advantages of the present invention, a high entropy garnet-based ceramic solid body is provided. The chemical formula of the high entropy garnet-based ceramic solid body is: 0.6 Gd 0.6 Sm 0.6 Eu 0.6 Dy 0.6 Fe5O 12 .

[0007] Preferably, the crystal grain size of the high entropy garnet-based ceramic solidified body is 0.50-0.75 μm, and the density is greater than 99%.

[0008] A method for preparing the high-entropy garnet-based ceramic solid body as described above comprises the following steps:

[0009] Step 1: Y2O3 powder, Fe2O3 powder, Gd2O3 powder, Sm2O3 powder, Eu2O3 powder and Dy2O3 powder are mixed and then ball-milled to obtain a precursor;

[0010] Step 2: After drying the precursor, place it in a graphite mold, then place the graphite mold in a spark plasma sintering furnace for sintering, and cool it to room temperature to obtain a sintered product;

[0011] Step 3: annealing the sintered product and then cooling it to room temperature in the furnace to obtain a high-entropy garnet-based ceramic solid body.

[0012] Preferably, in step 1, the Y2O3 powder, Fe2O3 powder, Gd2O3 powder, Sm2O3 powder, Eu2O3 powder and Dy2O3 powder are all of analytical grade and have a particle size of less than 5 μm.

[0013] Preferably, in step 1, the molar ratio of Y2O3 powder, Fe2O3 powder, Gd2O3 powder, Sm2O3 powder, Eu2O3 powder and Dy2O3 powder is 2-4:25:2-4:2-4:2-4:2-4.

[0014] Preferably, in the step 1, the ball milling speed is 200-400 r / min, and the ball milling time is 9-11 h.

[0015] Preferably, in step 2, the drying temperature is 70-90° C., and the drying time is 11-13 hours.

[0016] Preferably, in the step 2, the specific method of sintering is: under a sintering pressure of 30-50 MPa, heating to 1050-1150° C. at a heating rate of 80-100° C. / min, and keeping the temperature for 4-8 minutes to obtain a sintered product.

[0017] Preferably, in the step 2, the cooling rate to room temperature is 30-50° C. / min.

[0018] Preferably, in step three, the specific method of annealing is: placing the sintered product in an annealing device, heating it to 1000-1300° C. at a heating rate of 3-7° C., and keeping it warm for 1-3 hours.

[0019] The present invention has at least the following beneficial effects: the present invention successfully dissolves four simulated nuclides into high entropy garnet to prepare a high entropy garnet-based ceramic solid body Y 0.6 Gd 0.6 Sm 0.6 Eu 0.6 Dy 0.6 Fe5O 12 , achieving the simultaneous solidification of Gd, Sm, Eu and Dy multiple nuclides. The present invention also provides a method for preparing a high-entropy garnet-based ceramic solid body. The prepared high-entropy garnet-based ceramic solid body has fine and uniform grains with a particle size of 0.50 to 0.75 μm and a density greater than 99%. It also has excellent chemical stability, with a normalized leaching rate of 10% for 42 days. -7 ~10 -8 g·m -2 ·d -1 In addition, the present invention adopts a spark plasma sintering furnace for sintering, which can quickly prepare a high-entropy garnet-based ceramic solid body at low temperature, avoiding the problems of traditional solid-phase sintering methods requiring high sintering temperatures and long sintering times, thereby reducing production costs.

[0020] Other advantages, objectives and features of the present invention will be reflected in part from the following description and will be understood by those skilled in the art through study and practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 Flow chart of the preparation of the high entropy garnet-based ceramic solid body in Example 1;

[0022] Figure 2 XRD patterns of the high-entropy garnet-based ceramic solid body prepared in Example 1, the garnet-based ceramic solid bodies prepared in Comparative Examples 1 and 2, and the high-entropy garnet-based ceramic solid body prepared in Comparative Example 5;

[0023] Figure 3 XRD patterns of the high entropy garnet-based ceramic solid bodies prepared in Examples 1 and 2 and the garnet-based ceramic solid body prepared in Comparative Example 4;

[0024] Figure 4 This is an SEM image of the high-entropy garnet-based ceramic solid body prepared in Example 1;

[0025] Figure 5 The normalized leaching rate of each simulated nuclide in the high-entropy garnet-based ceramic solid body prepared in Example 1 in deionized water at 90°C for 42 days. DETAILED DESCRIPTION

[0026] The present invention will be described in further detail below in conjunction with the accompanying drawings so that those skilled in the art can implement the invention with reference to the description.

[0027] It should be understood that terms such as “having”, “including” and “comprising” used herein do not preclude the existence or addition of one or more other elements or combinations thereof.

[0028] Example 1

[0029] A method for preparing a high-entropy garnet-based ceramic solid body comprises the following steps:

[0030] Step 1: Y2O3 powder, Fe2O3 powder, Gd2O3 powder, Sm2O3 powder, Eu2O3 powder and Dy2O3 powder of analytical grade with a particle size of less than 5 μm are mixed, and the molar ratio of Y2O3 powder, Fe2O3 powder, Gd2O3 powder, Sm2O3 powder, Eu2O3 powder and Dy2O3 powder is 3:25:3:3:3:3, and then ball milled at a ball milling speed of 300 r / min and a ball milling time of 10 h to obtain a precursor;

[0031] Step 2: Place the precursor in an 80°C drying oven and dry it for 12 hours, then place it in a graphite mold, and then place the graphite mold in an electric spark plasma sintering furnace and heat it to a sintering temperature of 1100°C at a heating rate of 90°C / min and a sintering pressure of 40 MPa. Keep it warm for 5 minutes, and then cool it to room temperature at a cooling rate of 40°C / min to obtain a sintered product.

[0032] Step 3: Place the sintered product in a muffle furnace and heat it to an annealing temperature of 1200°C at a heating rate of 5°C / min, keep it warm for 2 hours, and then cool it to room temperature with the furnace to obtain a high-entropy garnet-based ceramic solid body.

[0033] According to tests, this embodiment forms a single-phase high-entropy garnet-based ceramic solid body, the grain size of which is 0.64±0.11 μm and the density is 99.31%.

[0034] The preparation flow chart of this embodiment is drawn, as shown in FIG. Figure 1 shown.

[0035] Example 2

[0036] The sintering time in this embodiment is 7 minutes, and the remaining steps are the same as those in Example 1.

[0037] The embodiment was tested to form a single-phase high-entropy garnet-based ceramic solidified body with a grain size of 0.63±0.08 μm and a density of 99.25%.

[0038] Comparative Example 1

[0039] The sintering temperature of the comparative example was 900°C, and the remaining steps were the same as those of Example 1.

[0040] The garnet-based ceramic solidified body of the comparative example was tested to have a ceramic structure of three phases (Fe2O3, perovskite, Y 0.6 Gd 0.6 Sm 0.6 Eu 0.6 Dy 0.6 Fe5O 12 ) coexisting, and was unable to form a single-phase high-entropy garnet-based ceramic solidified body.

[0041] Comparative Example 2

[0042] The sintering temperature of the comparative example was 1000°C, and the remaining steps were the same as those of Example 1.

[0043] The garnet-based ceramic solidified body of the comparative example was tested to have a ceramic structure of two phases (perovskite, Y 0.6 Gd 0.6 Sm 0.6 Eu 0.6 Dy 0.6 Fe5O 12 ) coexisting, and was unable to form a single-phase high-entropy garnet-based ceramic solidified body.

[0044] Comparative Example 3

[0045] The sintering temperature of the comparative example was 1200°C, and the remaining steps were the same as those of Example 1.

[0046] The sample of the comparative example was tested to have melted, and was unable to form a high-entropy garnet-based ceramic solidified body.

[0047] Comparative Example 4

[0048] The sintering time of the comparative example was 3 min, and the remaining steps were the same as those of Example 1.

[0049] The garnet-based ceramic solidified body of the comparative example was tested to have a ceramic structure of two phases (perovskite, Y 0.6 Gd 0.6 Sm 0.6 Eu 0.6 Dy 0.6 Fe5O 12 ) coexisting, and was unable to form a single-phase high-entropy garnet-based ceramic solidified body.

[0050] Comparative Example 5

[0051] The high-entropy garnet-based ceramic solidified body is prepared by a conventional solid-phase sintering method, comprising the following steps:

[0052] Step one, the Y2O3 powder, Fe2O3 powder, Gd2O3 powder, Sm2O3 powder, Eu2O3 powder and Dy2O3 powder with a particle size of less than 5 μm and an analytical grade are mixed, the molar ratio of the Y2O3 powder, Fe2O3 powder, Gd2O3 powder, Sm2O3 powder, Eu2O3 powder and Dy2O3 powder is 3:25:3:3:3:3, then ball milling is performed, the ball milling speed is 300 r / min, and the ball milling time is 10 h, to obtain a precursor;

[0053] Step two, the precursor is dried in a 80℃ drying box for 12 h, then is pressed into a cylindrical sheet with a height of 2 mm and a diameter of 12 mm under a pressure of 12 Mpa, is placed in a muffle furnace, is heated to a sintering temperature of 1300℃ at a heating rate of 5℃ / min, is kept for 24 h, and is cooled to room temperature with the furnace, to obtain a high-entropy garnet-based ceramic solidified body.

[0054] It is tested that the grain size of the high-entropy garnet-based ceramic solidified body of the comparative example is 2.89±0.29 μm, and the density is 96.5%.

[0055] Figure 2 The XRD patterns of the high-entropy garnet-based ceramic solidified body prepared in Example 1 and the garnet-based ceramic solidified bodies prepared in Comparative Examples 1-2 and Comparative Example 5 can be seen that, the garnet-based ceramic solidified body prepared in Comparative Example 1 exists a large amount of Y 0.6 Gd 0.6 Sm 0.6 Eu 0.6 Dy 0.6 Fe5O 12 phase, but also exists a perovskite phase and a Fe2O3 raw material phase; the main phase of the garnet-based ceramic solidified body prepared in Comparative Example 2 is Y 0.6 Gd 0.6 Sm 0.6 Eu 0.6 Dy 0.6 Fe5O 12 , the Fe2O3 raw material phase disappears, but a small amount of perovskite phase still exists; the phase of the high-entropy garnet-based ceramic solidified body prepared in Example 1 is Y 0.6 Gd 0.6 Sm 0.6 Eu 0.6 Dy 0.6 Fe5O 12, and a high-entropy garnet-based ceramic solid body with higher density can be obtained at 1100°C than that of the traditional solid-phase sintering at a higher sintering temperature (1300°C) and a longer sintering time (24h) in Comparative Example 5. Figure 3 The XRD patterns of the high entropy garnet-based ceramic solid bodies prepared in Examples 1 and 2 and the garnet-based ceramic solid bodies prepared in Comparative Example 4 show that the main phase of the garnet-based ceramic solid body prepared in Comparative Example 4 is Y 0.6 Gd 0.6 Sm 0.6 Eu 0.6 Dy 0.6 Fe5O 12 , and there is a small amount of perovskite phase; the phase of the high entropy garnet-based ceramic solid body prepared in Examples 1 and 2 is Y 0.6 Gd 0.6 Sm 0.6 Eu 0.6 Dy 0.6 Fe5O 12 Therefore, the preparation method of the present invention can quickly prepare a high-density high-entropy garnet-based ceramic solid body at a relatively low temperature.

[0056] Figure 4 This is an SEM image of the high-entropy garnet-based ceramic solid body prepared in Example 1. It can be seen that the high-entropy garnet-based ceramic solid body prepared in Example 1 has good crystallinity and fine and uniform grains, indicating that the preparation method of the present invention can obtain a high-entropy garnet-based ceramic solid body with high crystallinity and fine and uniform grains.

[0057] Figure 5 is the normalized leaching rate of each simulated nuclide in the high-entropy garnet-based ceramic solid body prepared in Example 1 in deionized water at 90°C for 42 days. It can be seen that the initial value of the leaching rate of each simulated nuclide in the high-entropy garnet-based ceramic solid body prepared in Example 1 is relatively high, and it decreases rapidly and tends to be stable over time. Among them, Y 3+ Stable at ~10 -8 g·m -2 ·d -1 Order of magnitude, Sm 3+ , Eu 3+ , Gd 3+ and Dy 3+ Stable at ~10 -7 g·m -2 ·d -1 This indicates that the high-entropy garnet-based ceramic solid body prepared by the preparation method of the present invention can not only solidify multiple nuclides at the same time, but also maintain excellent chemical stability.

[0058] Although the embodiments of the present invention have been disclosed above, they are not limited to the applications listed in the description and implementation methods. They can be fully applied to various fields suitable for the present invention. For those familiar with the art, additional modifications can be easily implemented. Therefore, without departing from the general concept defined by the claims and the scope of equivalents, the present invention is not limited to the specific details and illustrations shown and described herein.

Claims

1. A method for preparing a high-entropy garnet-based ceramic solid body, characterized in that: The chemical formula of the high entropy garnet-based ceramic solidified body is: 0.6 Gd 0.6 Sm 0.6 Eu 0.6 Dy 0.6 Fe5O 12 ; The method for preparing the high-entropy garnet-based ceramic solidified body comprises the following steps: Step 1: Y2O3 powder, Fe2O3 powder, Gd2O3 powder, Sm2O3 powder, Eu2O3 powder and Dy2O3 powder are mixed and then ball-milled to obtain a precursor; Step 2: After drying the precursor, place it in a graphite mold, then place the graphite mold in a spark plasma sintering furnace for sintering, and cool to room temperature to obtain a sintered product; wherein the specific method of the sintering is: under a sintering pressure of 30-50 MPa, heat up to 1050-1150°C at a heating rate of 80-100°C / min, keep warm for 4-8 minutes, and obtain a sintered product; the cooling rate to room temperature is 30-50°C / min; Step 3: annealing the sintered product and then cooling it to room temperature in the furnace to obtain a high-entropy garnet-based ceramic solid body; the specific method of annealing is: placing the sintered product in an annealing device, heating it to 1000-1300°C at a heating rate of 3-7°C, and keeping it warm for 1-3 hours.

2. The method for preparing a high-entropy garnet-based ceramic solidified body according to claim 1, wherein: The high-entropy garnet-based ceramic solidified body has a crystal particle size of 0.50-0.75 μm and a density greater than 99%.

3. The method for preparing a high-entropy garnet-based ceramic solidified body according to claim 1, wherein: In the step 1, the Y2O3 powder, Fe2O3 powder, Gd2O3 powder, Sm2O3 powder, Eu2O3 powder and Dy2O3 powder are all of analytical grade and have a particle size of less than 5 μm.

4. The method for preparing a high-entropy garnet-based ceramic solidified body according to claim 1, wherein: In the step 1, the molar ratio of Y2O3 powder, Fe2O3 powder, Gd2O3 powder, Sm2O3 powder, Eu2O3 powder and Dy2O3 powder is 2~4:25:2~4:2~4:2~4:2~4.

5. The method for preparing a high-entropy garnet-based ceramic solidified body according to claim 1, wherein: In the step 1, the ball milling speed is 200-400 r / min, and the ball milling time is 9-11 h.

6. The method for preparing a high-entropy garnet-based ceramic solidified body according to claim 1, wherein: In the step 2, the drying temperature is 70-90° C., and the drying time is 11-13 hours.

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