High-entropy ferrite rare earth-based perovskite ceramic solidified body and preparation method and application thereof

Abstract

The invention belongs to the technical field of high radioactive waste treatment, and relates to a high-entropy ferrite rare earth based perovskite ceramic solidified body and a preparation method and application thereof.The general formula of the solidified body is A1 / n (FexBy) O3, n represents the number of element types of the A lattice site of the high-entropy A1 / n (FexBy) O3 ferrite rare earth based perovskite ceramic solidified body, n is an integer and is larger than or equal to 3 and smaller than or equal to 7, and the A element types include Bi, Sc, La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Y, Ho, Er, Tm, Yb and Lu; m is at least three of transition metal elements including Cr, Mn, Co, Ni, Al, Ti, Zr, Hf, Nb, Ta and Ce, x is equal to 0.01 to 1.00, and x is equal to 0 to 0.99. According to the method, a high-entropy strategy is introduced into the ferrite rare earth perovskite ceramic solidified body, the ceramic solidified body not only can solidify various key high-radionuclides, but also has excellent chemical stability, low leaching rate and low preparation temperature, and the disadvantage that ceramic solidified nuclides are high in selectivity and single is effectively avoided. Due to the excellent performance of the ceramic solidified body, the ceramic solidified body has great application potential in the field of solidification treatment of high-radioactivity nuclear waste of a spent fuel reprocessing plant.

Description

Technical Field

[0001] This invention belongs to the field of high radioactive waste treatment technology, and relates to a high-entropy rare earth ferrite-based perovskite ceramic solidified body, its preparation method and application. Background Technology

[0002] With the continuous accumulation of large amounts of spent fuel containing uranium, plutonium, and fission products generated during nuclear power plant operations, my country has adopted a closed nuclear fuel cycle policy to ensure the safety of spent fuel and improve resource utilization. Therefore, the disposal of high-level radioactive waste containing actinides generated during spent fuel reprocessing has become a crucial aspect of spent fuel safety. High-level radioactive waste containing actinides (HLLW) is characterized by high radioactivity levels, strong radiation effects, complex composition, and high corrosiveness, posing a significant threat to the entire biosphere, especially the human living environment, and seriously affecting the sustainable development of nuclear energy.

[0003] For high-level radioactive waste, the main treatments include vitrification and the highly promising artificial rock ceramic solidification. Vitrification of high-level radioactive waste liquids is relatively mature and has already been applied in engineering. However, because glass is a thermodynamically metastable phase and an amorphous substance, it is easily affected by water or water vapor, which weakens the stability of the glass's network structure, leading to the destruction of the material's integrity and affecting the safety of long-term storage. Artificial rock solidification, on the other hand, can fix almost all the nuclides contained in high-level radioactive waste within the crystalline phase. It not only has the advantages of easy processing but also high mechanical strength, strong chemical stability, and good resistance to leaching, making it considered a more ideal solidification method for treating high-level radioactive waste liquids. Artificial rock ceramic solidification is based on isomorphism, mixing radionuclides with a solidification substrate and then sintering to prepare a ceramic solidified body, fixing the radionuclides in the ceramic phase lattice position. Ceramic solidification is currently in the research stage and has not yet been practically applied. Its advantages lie in its excellent physical and chemical properties, high safety factor, and promising engineering applications for long-term disposal. However, its disadvantages include high selectivity for solidified nuclides, a relatively singular nature, and a relatively complex process.

[0004] Lanthanum ferrite (LaFeO3, LFO), a type of ceramic material with an ABO3 perovskite structure, has been widely used in sensors, catalysts, and batteries due to its high stability and flexibility in composition and structure. Compared to the characteristics of high-level radioactive waste (HLLW) mentioned above and the high stability requirements of high-level radioactive waste solidification, these features of LFO materials make them a promising candidate as a ceramic solidification substrate. However, for homogeneous ceramic solidification matrices, the single-component perovskite structure exhibits radionuclide selectivity, which poses a challenge for the treatment of complex, multi-element high-level radioactive waste. Therefore, new systems need to be developed to address this problem.

[0005] In recent years, high entropy has become a new strategy for regulating material properties. It has theoretical advantages in the preparation of solidified high-level radioactive waste. As the entropy value increases, the Gibbs free energy decreases, which promotes the formation of single-phase solid solutions and lowers the preparation temperature. Compared with the selective solidification of radionuclides by traditional single-component ceramic solidification substrates, high-entropy ceramics have five or more elements occupying lattice positions, thus allowing the addition of multiple solidification elements from high-strength materials. High-entropy ceramics can not only simultaneously solidify multiple different radionuclides, but also have excellent chemical stability (Ceramics International, 2024, (50)4: 5955-5961), but there is limited research on its radiation resistance and mechanical properties. Summary of the Invention

[0006] In view of this, the present invention addresses the limitations of existing ceramic curing bodies, which have strong but relatively singular curing nuclide selectivity and complex process flow. It provides a high-entropy strategy to develop high-entropy rare earth ferrite-based perovskite ceramic curing bodies with excellent curing performance.

[0007] It should be noted that, similar to high-entropy alloys, high-entropy ceramic materials contain a variety of randomly distributed elements within their unit cells, significantly increasing the material's entropy value. This also exhibits the four major effects of high entropy: the thermodynamic high-entropy effect, the kinetic hysteresis diffusion effect, the structural lattice distortion effect, and the performance cocktail effect. Compared to traditional ceramics, high-entropy ceramics, due to their complex composition and significant lattice distortion, exhibit superior thermal and mechanical properties.

[0008] The first technical objective of this invention is to provide a high-entropy rare-earth ferrite-based perovskite ceramic solidified body, wherein the general chemical formula of the high-entropy rare-earth ferrite-based perovskite ceramic solidified body is: A 1 / n (Fe x B y O3; where n represents high entropy A 1 / n (Fe x B y The number of element types in lattice sites A of the O3 rare earth ferrite-based perovskite ceramic solidified body, where n is an integer and 3≤n≤7; element A includes at least three of Bi, Sc, La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Y, Ho, Er, Tm, Yb, and Lu; element B is at least three of transition metal elements Cr, Mn, Co, Ni, Al, Ti, Zr, Hf, Nb, Ta, and Ce, and x=0.01~1.00, y=0~0.99.

[0009] The second technical objective of this invention is to provide a method for preparing a high-entropy rare-earth ferrite-based perovskite ceramic solidified body as described above, comprising the following steps: (1) Mix and dissolve source A, source Fe and source B in deionized water, and stir magnetically for 2 min to 180 min. Then add chelating agent and stir for another 2 min to 180 min. (2) Transfer the solution obtained in step (1) to a stainless steel autoclave, seal it, and perform a hydrothermal reaction; then, allow the autoclave to cool naturally to room temperature, centrifuge to separate the brown precipitate, and wash it with deionized water and ethanol at 40°C. o C~80 o Drying at C; (3) The precipitate obtained in step (2) is heat-treated in a muffle furnace and then ground and sieved in an agate mortar to obtain A. 1 / n (Fe x B y )O3 powder; (4) Take the A obtained in step (3) 1 / n (Fe x B y O3 powder is ball-milled and ready for use; (5) Grind A obtained in step (4) 1 / n (Fe x B y O3 powder is pressed into discs under a pressure of 1~120MPa and then sintered in a muffle furnace. (6) Repeat steps (4) and (5) 1 to 5 times to obtain a high-entropy rare earth ferrite-based perovskite ceramic solidified body, A 1 / n (Fe x B y )O3.

[0010] Optionally, source A is at least one of oxides, nitrates, chlorides, carbonates, and acetates; source Fe is at least one of Fe powder, Fe oxides, nitrates, chlorides, carbonates, and acetates; and source B is at least one of oxides, nitrates, chlorides, carbonates, and acetates.

[0011] Furthermore, the molar ratio of source A to the sum of source Fe and source B is 0.4 to 1:1.

[0012] Optionally, the chelating agent is one or a combination of citric acid, oxalic acid, tannic acid, glycyrrhizic acid, caffeic acid, and tartaric acid, and the mass ratio of the chelating agent to the total mass of source A, source Fe, and source B is 1 to 20:1.

[0013] Optionally, in step (2), the temperature of the hydrothermal reaction is 100°C. o C~180 o C, the reaction time is 1h~48h.

[0014] Optionally, the heat treatment in step (3) is: at 300 oC~1200 o Keep warm at C for 1 to 48 hours.

[0015] Optionally, in step (4), the ball milling operation is as follows: The A obtained in step (3) 1 / n (Fe x B y O3 powder is added to a ball mill and ground at a ball-to-material mass ratio of 1:1 to 200:1, a grinding speed of 100 rpm to 2000 rpm, and a grinding time of 0.2 h to 12 h.

[0016] Optionally, in step (5), the sintering process is 10... o Increase the temperature by 300~700 C / min. o C, then 5 o Increase the temperature by 800~1400 °C / min o C, keep warm for 0.5~48h.

[0017] The third technical objective of this invention is to provide a high-entropy rare-earth ferrite-based perovskite ceramic solidified body prepared by the method described above for solidification treatment of highly radioactive nuclear waste in spent fuel reprocessing plants.

[0018] Compared with the prior art, the beneficial effects of the present invention are as follows: This invention introduces a high-entropy strategy into rare-earth ferrite perovskite ceramic solidification bodies. These solidified ceramic bodies not only solidify a variety of key high-level radionuclides but also possess excellent chemical stability, low leaching rate, and low preparation temperature, effectively avoiding the disadvantages of ceramic solidification's high selectivity and limited range of radionuclides. The superior performance of this ceramic solidification body makes it highly promising for the solidification and treatment of high-level radioactive waste in spent fuel reprocessing plants. Attached Figure Description

[0019] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.

[0020] Figure 1 The X-ray diffraction pattern of the high-entropy rare earth ferrite perovskite ceramic solidified body prepared in this invention is shown.

[0021] Figure 2 Scanning electron microscope (SEM) image of the high-entropy rare-earth ferrite perovskite ceramic solidified body prepared according to the present invention. Detailed Implementation

[0022] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0023] The term "embodiment" used herein, as an example, is not necessarily to be construed as superior to or better than other embodiments. Performance testing in the embodiments of this application, unless otherwise specified, employs conventional testing methods in the art. It should be understood that the terminology used in this application is merely for describing particular implementations and is not intended to limit the scope of this disclosure.

[0024] Unless otherwise stated, the technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains; other experimental methods and technical means not specifically mentioned herein refer to experimental methods and technical means commonly used by one of ordinary skill in the art.

[0025] To better illustrate the content of this application, numerous specific details are provided in the following detailed embodiments. Those skilled in the art should understand that this application can be implemented even without certain specific details. In the embodiments, some methods, means, instruments, and devices well known to those skilled in the art are not described in detail in order to highlight the main points of this application.

[0026] Without conflict, the technical features disclosed in the embodiments of this application can be combined arbitrarily, and the resulting technical solution belongs to the content disclosed in the embodiments of this application.

[0027] This invention discloses a high-entropy rare earth ferrite-based perovskite ceramic solidified body and its preparation method.

[0028] The preparation and properties of the high-entropy rare earth ferrite perovskite ceramic solidified body of the present invention will be further illustrated below through specific embodiments.

[0029] Example 1: La 1 / 5 Y 1 / 5 Sm 1 / 5 Nd 1 / 5 Gd 1 / 5 FeO3 1.30 g lanthanum nitrate, 0.78 g yttrium chloride, 0.70 g samarium oxide, 1.32 g neodymium nitrate, 1.34 g gadolinium acetate, and 4.83 g ferric nitrate were mixed and dissolved in deionized water. The mixture was magnetically stirred for 180 min, then 10 g citric acid was added, and the mixture was stirred for another 180 min. The resulting solution was transferred to a stainless steel autoclave, sealed, and sterilized at 100 °C. oThe hydrothermal reaction was carried out at C for 48 hours. Afterwards, the autoclave was allowed to cool naturally to room temperature, the brown precipitate was separated by centrifugation, and washed with deionized water and ethanol. The precipitate was then subjected to a hydrothermal reaction at 40°C. o Dry at C. The resulting precipitate is then heated in a muffle furnace at 1200 °C. o After being kept at C for 1 hour, La was obtained by grinding and sieving in an agate mortar. 1 / 5 Y 1 / 5 Sm 1 / 5 Nd 1 / 5 Gd 1 / 5 FeO3 powder was then added to a ball mill and ground at a ball-to-powder mass ratio of 1:1 at a speed of 100 rpm / min for 12 hours. After grinding, the powder was pressed into discs under a pressure of 50 MPa and then placed in a muffle furnace at 100 rpm / min. o Temperature increased to 700 °C / min o C, then 5 o Temperature increased to 1400 °C / min o C, hold at this temperature for 0.5 h. Repeat the ball milling, pressing, and sintering process three times to obtain high-entropy rare earth ferrite-based perovskite ceramic La. 1 / 5 Y 1 / 5 Sm 1 / 5 Nd 1 / 5 Gd 1 / 5 FeO3 solidified body.

[0030] Example 2: Bi 1 / 7 Sc 1 / 7 La 1 / 7 Eu 1 / 7 Sm 1 / 7 Nd 1 / 7 Gd 1 / 7 (Fe 0.9 Ni 0.1 O3 1.13g bismuth nitrate, 0.43g scandium chloride, 1.31g lanthanum carbonate, 0.97g europium nitrate, 0.94g samarium acetate, 4.35g ferric nitrate, and 0.26g nickel chloride were mixed and dissolved in deionized water. The mixture was magnetically stirred for 20 minutes, then 188g tartaric acid was added, and the mixture was stirred for another 20 minutes. The resulting solution was transferred to a stainless steel autoclave, sealed, and sterilized at 150°C. o The hydrothermal reaction was carried out at C for 24 hours. Afterwards, the autoclave was allowed to cool naturally to room temperature, the brown precipitate was separated by centrifugation, and washed with deionized water and ethanol. The precipitate was then subjected to a hydrothermal reaction at 60°C. o Dry at C. The resulting precipitate is then heated in a muffle furnace at 1000 °C. o Bi was obtained by heating at C for 15 hours and grinding and sieving in an agate mortar. 1 / 7 Sc 1 / 7La 1 / 7 Eu 1 / 7 Sm 1 / 7 Nd1 / 7 Gd 1 / 7 Fe 0.9 Ni 0.1 O3 powder was then added to a ball mill and ground at a ball-to-powder mass ratio of 200:1 for 12 hours at a speed of 500 rpm / min. The ground powder was then pressed into discs under 100 MPa pressure and placed in a muffle furnace at 100 rpm. o Heat up to 500 °C / min o C, then 5 o Temperature increased to 1200 °C / min o C, hold at this temperature for 24 hours. Repeat the ball milling, pressing, and sintering process once to obtain high-entropy rare earth ferrite-based perovskite ceramic Bi. 1 / 7 Sc 1 / 7 La 1 / 7 Eu 1 / 7 Sm 1 / 7 Nd 1 / 7 Gd 1 / 7 Fe 0.9 Ni 0.1 O3 solidified body.

[0031] Example 3: Eu 1 / 3 Gd 1 / 3 Ho 1 / 3 (Fe 0.6 Ni 0.2 Co 0.2 O3 Dissolve 3.23g europium carbonate, 1.76g gadolinium chloride, 10.20g holmium carbonate, 1.95g ferric chloride, 0.73g nickel nitrate, and 0.48g cobalt carbonate in deionized water. Add 184g tartaric acid. Transfer the resulting solution to a stainless steel autoclave, seal it, and autoclave at 180°C. o The hydrothermal reaction was carried out at C for 1 hour. Afterwards, the autoclave was allowed to cool naturally to room temperature, the brown precipitate was separated by centrifugation, and washed with deionized water and ethanol. The precipitate was then subjected to a final reaction at 80°C. o Dry at C. The resulting precipitate is then heated in a muffle furnace at 1000 °C. o Eu was obtained by heating at C for 10 hours and grinding and sieving in an agate mortar. 1 / 3 Gd 1 / 3 Ho 1 / 3 (Fe 0.6 Ni 0.2 Co 0.2 O3 powder was then added to a ball mill and ground at a ball-to-powder mass ratio of 100:1 for 10 hours at a speed of 800 rpm / min. The ground powder was then pressed into discs under 120 MPa pressure and placed in a muffle furnace at 100 rpm / min. o Heat to 600 °C / min o C, then 5 oTemperature increased to 800 °C / min o C, hold at this temperature for 48 hours. Repeat the ball milling, pressing, and sintering process five times to obtain high-entropy rare-earth ferrite-based perovskite ceramic Eu. 1 / 3 Gd 1 / 3 Ho 1 / 3 (Fe 0.6 Ni 0.2 Co 0.2 )O3 solidified body.

[0032] Example 4: La 1 / 6 Pr 1 / 6 Nd 1 / 6 Sm 1 / 6 Dy 1 / 6 Lu 1 / 6 (Fe 0.99 Mn 0.01 O3 A mixture of 1.53 g lanthanum carbonate, 0.82 g praseodymium chloride, 1.62 g neodymium carbonate, 0.86 g samarium chloride, 1.16 g dysprosium nitrate, 1.26 g lutetium nitrate, 1.58 g ferric oxide, and 0.04 g manganese nitrate was dissolved in deionized water. 45 g tannic acid was added, and the resulting solution was transferred to a stainless steel autoclave, sealed, and sterilized at 150 °C. o The hydrothermal reaction was carried out at C for 10 hours. Afterwards, the autoclave was allowed to cool naturally to room temperature, the brown precipitate was separated by centrifugation, and washed with deionized water and ethanol. The precipitate was then subjected to a final reaction at 80°C. o Dry at C. The resulting precipitate is then heated in a muffle furnace at 1100 °C. o La was obtained by heating at C for 8 hours and then grinding and sieving in an agate mortar. 1 / 6 Pr 1 / 6 Nd 1 / 6 Sm 1 / 6 Dy 1 / 6 Lu 1 / 6 (Fe 0.99 Mn 0.01 O3 powder was then added to a ball mill and ground at a ball-to-powder mass ratio of 80:1 for 5 hours at a speed of 1200 rpm / min. The ground powder was then pressed into discs under 20 MPa pressure and placed in a muffle furnace at 10... o Heat up to 400 °C / min o C, then 5 o Temperature increased to 1200 °C / min o C, hold at this temperature for 36 hours. Repeat the ball milling, pressing, and sintering process twice to obtain high-entropy rare-earth ferrite-based perovskite ceramic La. 1 / 6 Pr 1 / 6 Nd 1 / 6 Sm 1 / 6 Dy 1 / 6 Lu 1 / 6 (Fe 0.99Mn 0.01 )O3 solidified body.

[0033] To further demonstrate the beneficial effects of the present invention and to better understand it, the following experimental examples and comparative examples further illustrate the technical features disclosed in the present invention, but should not be construed as limiting the present invention. Other improvements made by those skilled in the art based on the above-described invention, without inventive effort, are also considered to fall within the protection scope of the present invention.

[0034] Comparative example: LaFeO3 cured body Dissolve 6.49 g of lanthanum nitrate and 4.83 g of ferric nitrate in deionized water, add 45 g of tannic acid, transfer the resulting solution to a stainless steel autoclave, seal, and autoclave at 150 °C. o The hydrothermal reaction was carried out at C for 10 hours. Afterwards, the autoclave was allowed to cool naturally to room temperature, the brown precipitate was separated by centrifugation, and washed with deionized water and ethanol. The precipitate was then subjected to a final reaction at 80°C. o Dry at C. The resulting precipitate was then heated in a muffle furnace at 1300 °C. o The mixture was kept at a temperature of 8°C for 8 hours and then ground and sieved in an agate mortar to obtain LaFeO3 powder. The powder was then added to a ball mill and ground at a ball-to-powder mass ratio of 80:1 at a speed of 1200 rpm / min for 5 hours. After grinding, the powder was pressed into discs under a pressure of 20 MPa and placed in a muffle furnace at 10... o Heat up to 400 °C / min o C, then 5 o Temperature increased to 1300 °C / min o C, heat for 36 hours. Repeat the ball milling, pressing, and sintering process 5 times to obtain the LaFeO3 ceramic cured body. Compared with Examples 1-4, the leaching rate of La in the LaFeO3 cured body reached 7×10⁻⁶ after 28 days. -3 ~10×10 -3 g / m 2 ·d, which is significantly higher than that of high-entropy rare earth ferrite-based perovskite ceramic solidified bodies.

[0035] Experimental Example: Structural and Property Characterization of High-Entropy Rare Earth Ferrate-Based Perovskite Ceramic Solids 1. X-ray diffraction pattern Figure 1The X-ray diffraction pattern of the high-entropy rare earth ferrite perovskite ceramic solidified body prepared in this invention is shown. As shown in the figure, the prepared samples H1 (comparative example) and H2 (Example 1) correspond to the standard cards of perovskite lanthanum ferrite and perovskite neodymium ferrite, respectively, and the diffraction peaks at 22.87º, 25.63º, 32.07º, 32.62º, 32.99º, 34.16º, 38.67º, 39.81º, 40.58º and 41.99º, 46.66º, 46.93º, 47.59º, 48.18º, 52.79º, 53.67º, 57.51º and 58.10º correspond to the (020), (111), (200), (121), (020), (210), (201), (112), (220) and (022) crystal planes of perovskite.

[0036] 2. Scanning electron microscopy analysis Figure 2 SEM surface morphology images of the high-entropy rare-earth ferrite perovskite ceramic solidified body prepared according to the present invention (Example 1). The results show that the sintered high-entropy ceramic solidified body is a dense ceramic block with few pores. The average grain size of the high-entropy ceramic is 2~5μm, exhibiting regular polygonal grains and clear grain boundaries.

[0037] 3. PCT leaching rate According to ASTM and current WTP standards, the leaching test of the cured body was conducted using the MCC-1 method. The specific steps are as follows: The entire leaching test was carried out in a PTFE hydrothermal tank with a stainless steel outer shell. First, the cylindrical ceramic sample prepared in Example 1 was tied and fixed with a fishhook line and suspended in deionized water, maintaining the ratio of leachate volume to sample surface area at approximately 1:1. The hydrothermal tank was placed in a 90°C oven, and the leachate was sampled on days 0, 7, 14, and 28. After obtaining all samples, the content of rare earth elements (La, Y, Gd, Nd, and Sm) in the leachate was determined and estimated by inductively coupled plasma optical emission spectrometry (ICP-OES) or inductively coupled plasma mass spectrometry (ICP-MS). The results are listed in Table 1 below: The concentrations of rare earth ions in the leached sample filtrate were all on the order of 10. -6 ~10 -4 All are within the limits, therefore the curing performance of the cured body meets the requirements.

[0038] Table 1 shows the normalized leaching rates (g / m³) of La, Y, Sm, Nd, and Gd. 2 ·d)

[0039] In summary, this invention prepares a high-entropy rare-earth ferrite perovskite ceramic solidified body. Through the high-entropy material constructed by the entropy strategy, the simulated solidification of various actinide nuclides in highly radioactive waste is achieved.

[0040] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A high-entropy rare-earth ferrite-based perovskite ceramic solidified body, characterized in that, The general chemical formula of the high-entropy rare-earth ferrite-based perovskite ceramic solidified body is: A 1 / n (Fe x B y O3; where n represents high entropy A 1 / n (Fe x B y The number of element types in lattice sites A of the O3 rare earth ferrite-based perovskite ceramic solidified body, where n is an integer and 3≤n≤7; element A includes at least three of Bi, Sc, La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Y, Ho, Er, Tm, Yb, and Lu; element B is at least three of transition metal elements Cr, Mn, Co, Ni, Al, Ti, Zr, Hf, Nb, Ta, and Ce, and x=0.01~1.00, y=0~0.

99.

2. A method for preparing a high-entropy rare-earth ferrite-based perovskite ceramic solidified body as described in claim 1, characterized in that, Includes the following steps: (1) Mix and dissolve source A, source Fe and source B in deionized water, stir and then add chelating agent; (2) Transfer the solution obtained in step (1) to a stainless steel autoclave, seal it, and perform a hydrothermal reaction; then, allow the autoclave to cool naturally to room temperature, centrifuge to separate the brown precipitate, wash it with deionized water and ethanol, and dry it. (3) The precipitate obtained in step (2) is heat-treated in a muffle furnace and then ground and sieved in an agate mortar to obtain A. 1 / n (Fe x B y )O3 powder; (4) Take the A obtained in step (3) 1 / n (Fe x B y O3 powder is ball-milled and ready for use; (5) Grind A obtained in step (4) 1 / n (Fe x B y O3 powder is pressed into discs and sintered in a muffle furnace. (6) Repeat steps (4) and (5) 1 to 5 times to obtain a high-entropy rare earth ferrite-based perovskite ceramic solidified body, A 1 / n (Fe x B y )O3.

3. The method for preparing the high-entropy rare-earth ferrite-based perovskite ceramic solidified body as described in claim 2, characterized in that, Source A is at least one of oxides, nitrates, chlorides, carbonates, and acetates; source Fe is at least one of Fe powder, Fe oxides, nitrates, chlorides, carbonates, and acetates; source B is at least one of oxides, nitrates, chlorides, carbonates, and acetates.

4. The method for preparing the high-entropy rare-earth ferrite-based perovskite ceramic solidified body as described in claim 2 or 3, characterized in that, The molar ratio of source A to the sum of source Fe and source B is 0.4 to 1:

1.

5. The method for preparing the high-entropy rare-earth ferrite-based perovskite ceramic solidified body as described in claim 2, characterized in that, The chelating agent is one or a combination of several of citric acid, oxalic acid, tannic acid, glycyrrhizic acid, caffeic acid, and tartaric acid, and the mass ratio of the chelating agent to the total mass of source A, source Fe, and source B is 1 to 20:

1.

6. The method for preparing the high-entropy rare-earth ferrite-based perovskite ceramic solidified body as described in claim 2, characterized in that, In step (2), the temperature of the hydrothermal reaction is 100°C. o C~180 o C, the reaction time is 1h~48h.

7. The method for preparing the high-entropy rare-earth ferrite-based perovskite ceramic solidified body as described in claim 2, characterized in that, The heat treatment in step (3) is as follows: at 300 o C~1200 o Keep warm at C for 1 to 48 hours.

8. The method for preparing the high-entropy rare-earth ferrite-based perovskite ceramic solidified body as described in claim 2, characterized in that, In step (4), the ball milling operation is as follows: The A obtained in step (3) 1 / n (Fe x B y O3 powder is added to a ball mill and ground at a ball-to-material mass ratio of 1:1 to 200:1, a grinding speed of 100 rpm to 2000 rpm, and a grinding time of 0.2 h to 12 h.

9. The method for preparing the high-entropy rare-earth ferrite-based perovskite ceramic solidified body as described in claim 2, characterized in that, In step (5), the sintering process is 10 o Increase the temperature by 300~700 C / min. o C, then 5 o Increase the temperature by 800~1400 °C / min o C, keep warm for 0.5~48h.

10. A high-entropy rare-earth ferrite-based perovskite ceramic solidified body as described in claim 1 or a high-entropy rare-earth ferrite-based perovskite ceramic solidified body prepared by the method described in claim 2 is applied to the field of solidification treatment of high-level radioactive nuclear waste.

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