NZP-high-entropy (Ln1 / n) PO4 monazite type multiphase ceramic solidified body and preparation method thereof

Abstract

The invention discloses an NZP-high-entropy (Ln1 / n) PO4 monazite type multiphase ceramic solidified body and a preparation method thereof, the chemical general formula of the NZP-high-entropy (Ln1 / n) PO4 monazite type multiphase ceramic solidified body is (1-x) Sr0. 5Zr2 (PO4) 3-x (Ln1 / n) PO4, x represents molar percentage, the value range is 0.1-0.9, x represents molar percentage, and the value range is 0.1-0.9. The NZP-high-entropy (Ln1 / n) PO4 monazite type multiphase ceramic solidified body is NZP-high-entropy (Ln1 / n) PO4 monazite type multiphase ceramic solidified body. N represents the number of element types of Ln lattice sites in the high-entropy (Ln1 / n) PO4 monazite type, and n is an integer and is larger than or equal to 5 and smaller than or equal to 7; the Ln element types comprise La, Nd, Sm, Eu, Gd, Ho, Er, Sr0. 5Zr2 (PO4) 3 and (Ln1 / n) PO4, and the molar ratio of the Ln element types to the Sr0. 5Zr2 (PO4) 3 to the (Ln1 / n) PO4 can be freely regulated and controlled. The NZP-high-entropy (Ln1 / n) PO4 monazite type multiphase ceramic solidified body adopts an in-situ preparation process, and integration of crystal phase synthesis and sintering densification can be realized. The preparation method comprises the following steps: uniformly mixing the raw materials, pretreating, adding a sintering aid, mixing again, granulating and aging the obtained powder, molding, removing plastic, and sintering to obtain the NZP-high-entropy (Ln1 / n) PO4 monazite type composite ceramic solidified body. The preparation process disclosed by the invention has the advantages of flexible composition design, capability of simultaneously curing various fission products and (sub) actinide series nuclides, short preparation period, low production energy consumption, high product compactness and the like.

Description

Technical Field

[0001] The present invention belongs to the technical field of high-level radioactive nuclear waste solidification substrates, and more specifically, the present invention relates to a NZP-high entropy (Ln 1 / n )PO4 monazite type composite ceramic solid body and preparation method thereof. Background Art

[0002] High-level waste (HLW) mainly refers to high-level waste liquid and its solidified bodies generated during the reprocessing of spent fuel, spent fuel to be directly disposed of, and other wastes of corresponding radioactive levels. HLW has a complex composition, contains a large number of (minor) actinide nuclides (Np, Am, Cm), fission products (Sr, Cs, I) and transuranic elements (Pu), is extremely radioactive, and is extremely difficult to handle and dispose of. my country's HLW disposal adopts the internationally recognized "solidification-deep geological disposal" technical route, that is, the radioactive nuclides are fixed or contained in the solidified matrix with the help of a solidified matrix, and then buried deep in an underground disposal repository to be isolated from the biosphere as completely as possible. The solidification of HLW includes glass solidification, glass-ceramic solidification and ceramic solidification. Among them, ceramic solidification is to fix the nuclides in a certain lattice position in the crystal structure of the ceramic component phase. Its solidified body has better anti-leaching, anti-irradiation damage and thermal stability, and is considered to be the second generation of HLW solidified body after the glass solidified body. However, due to the limitation of crystal structure, the single-phase ceramic solid body can only have a high inclusion capacity and adaptability to certain specific radionuclides, and the types of solid-solid nuclides are limited. It cannot simultaneously solidify and treat multiple fission and (minor) actinide nuclides in HLW, which greatly limits its application prospects. For example, ceramics such as monazite, perovskite, and pyrochlore are suitable for solidifying (minor) actinide nuclides in HLW; while ceramics such as sodium zirconium phosphate, alkali manganese ore, and perovskite are more suitable for solidifying fission nuclides Sr and Cs.

[0003] Sodium zirconium phosphate (NaZr2(PO4)3, abbreviated as NZP) and monazite (LnPO4, Ln=La, Ce, Pr, Nd, Sm, Eu, Gd) have rich ion substitution, and excellent hydrolysis stability, mechanical properties, anti-leaching performance and radiation stability, becoming the research hotspot of ceramic solidification substrates. In recent years, studies have shown that the crystal structure characteristics of NZP and monazite can be combined to prepare NZP-monazite type composite ceramic solid bodies that can simultaneously solidify fission products and (minor) actinides. In recent years, with the emergence of "high entropy ceramics", researchers have tried to use high entropy ceramics to simultaneously solidify more than 5 (minor) actinides in HLW. High entropy ceramics refer to ceramic solid solution materials with high configuration entropy and composed of at least five different cations and anions. Ceramic solid solutions formed by equimolar or nearly equimolar mixing of multiple components (five components or more) show a high degree of structural disorder, and the configuration entropy is significantly increased. This gives high entropy ceramics some unique effects, mainly including high entropy effect, lattice distortion effect, hysteresis diffusion effect and "cocktail" effect. These effects make high entropy ceramics have high melting point, high temperature mechanical properties, excellent chemical stability and irradiation stability, and good corrosion resistance, making it a candidate substrate for nuclear solidification substrate. Therefore, based on the concept of high entropy, if the crystal structure advantages of the above two or more ceramic crystalline phases suitable for solidifying fission and (minor) actinide nuclides can be combined to prepare high entropy composite ceramic solid bodies, and by regulating the phase composition of the solid body, the fission, Ln and (minor) actinide nuclides in HLW can be dissolved in the lattices of each crystalline phase of the composite ceramic solid body respectively. This will have important scientific and practical significance for the high inclusion solidification treatment of HLW with complex components, and it is also an important research direction of ceramic solidification.

[0004] The object of the present invention is to provide a "NZP-high entropy (Ln)" system capable of simultaneously solidifying fission products and different types of (minor) actinide nuclides in HLW. 1 / n )PO4 monazite-type composite ceramic solid body design composition and preparation method. In the selection of simulated nuclides, usually 88 Sr simulated fission products 90 Sr is dissolved into the NZP structure, Ln 3+ (Ln=La, Nd, Sm, Eu, Gd, Ho, Er) simulates the solid dissolution of (minor) actinide nuclides into the monazite structure. The in-situ preparation process is used to achieve the integration of phase synthesis and sintering densification of the composite ceramic solid body. Compared with the two-step process of first synthesizing the phase, then compounding and then sintering in the traditional composite ceramic preparation, this preparation process can greatly shorten the preparation cycle, reduce production energy consumption, and the prepared solid body has high density and excellent chemical stability. 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 advantages according to the present invention, a NZP-high entropy (Ln 1 / n )PO4 monazite type composite ceramic solid body, the NZP-high entropy (Ln 1 / n The chemical formula of the solidified composite ceramic body of )PO4 monazite is: (1-x)Sr 0.5 Zr2(PO4)3-x(Ln 1 / n )PO4, where x represents the molar percentage, ranging from 0.1 to 0.9; n represents the high entropy (Ln 1 / n ) The number of element types in the Ln lattice position in the PO4 monazite type, n is an integer and 5≤n≤7; at the same time, the Ln element types include La, Nd, Sm, Eu, Gd, Ho, Er, and Sr in the composite ceramic solid body 0.5 Zr2(PO4)3 and (Ln 1 / n )PO4 molar ratio can be adjusted arbitrarily.

[0007] Preferably, when n is 5, Ln 1 / 5 =La 1 / 5 Nd 1 / 5 Sm 1 / 5 Eu 1 / 5 G 1 / 5 ;

[0008] When n is 6, Ln 1 / 6 =La 1 / 6 Nd 1 / 6 Sm 1 / 6 Eu 1 / 6 G 1 / 6 Ho 1 / 6 ;

[0009] When n is 7, Ln 1 / 7 =La 1 / 7 Nd 1 / 7 Sm 1 / 7 Eu 1 / 7 G 1 / 7 Ho 1 / 7 Er 1 / 7 .

[0010] Preferably, wherein the NZP-high entropy (Ln 1 / n The crystal phase composition of the PO4 monazite composite ceramic solid body contains only Sr 0.5 Zr2(PO4)3 and (Ln 1 / n )PO4 two crystal phases.

[0011] Preferably, wherein the NZP-high entropy (Ln1 / n )The relative density of the PO4 monazite composite ceramic solid body reaches 95-98%.

[0012] A NZP-high entropy (Ln 1 / n The invention discloses a method for preparing a composite ceramic solid body of )PO4 monazite type, comprising: using strontium nitrate, ammonium dihydrogen phosphate, zirconium oxide and at least five of seven oxides of lanthanum oxide, neodymium oxide, samarium oxide, europium oxide, gadolinium oxide, holmium oxide and erbium oxide as raw materials, mixing the raw materials uniformly and then pre-treating them to obtain pre-treated powders, adding a sintering aid to the pre-treated powders and mixing them again, adding a binder to the obtained powders for granulation and aging, and then forming and discharging the powders, and finally preparing NZP-high entropy (Ln) in situ by sintering. 1 / n )PO4 monazite type composite ceramic solid body.

[0013] Preferably, the raw materials are mixed by mechanical mixing using any one of a ball mill and a jet mill, and the mixing time is 12 to 24 hours.

[0014] Preferably, the pretreatment process is: calcination pretreatment at 600-700° C. in a muffle furnace for 4-8 hours.

[0015] Preferably, the sintering aid is ZnO, and the added amount is 0.5-1.5wt.% of the mass of the pretreated powder; the binder is polyvinyl alcohol solution, the concentration of the polyvinyl alcohol solution is 6-8wt.%, and the amount of polyvinyl alcohol is 5-7wt.% of the mass of the raw material powder.

[0016] Preferably, the molding is isostatic pressing or dry pressing, the pressure is 200-250 MPa, and the holding time is 3-5 min. The plastic discharge process is: the plastic discharge temperature is 600-700° C., and the holding time is 0.5-1.5 h.

[0017] Preferably, the sintering is any one of conventional solid phase sintering and microwave sintering, the sintering temperature is 1050-1250° C., and the holding time is 1.5-2.5 h.

[0018] In order to improve the NZP-high entropy (Ln 1 / n ) The volume density and relative density of the PO4 monazite type composite ceramic solid body are obtained by replacing the polyvinyl alcohol solution with an equal mass of modified polyvinyl alcohol solution during granulation; wherein the preparation method of the modified polyvinyl alcohol solution comprises:

[0019] S1. Using dichloromethane as solvent, polyacrylic acid and polyethylene glycol are mixed uniformly in the solvent, and catalysts dicyclohexylcarbodiimide and 2,6-lutidine are added. After stirring and mixing, the mixture is heated in a water bath to 50-60° C. for reaction, and the reaction time is 12-24 hours; wherein the amount ratio of dichloromethane, polyacrylic acid, polyethylene glycol, dicyclohexylcarbodiimide and 2,6-lutidine is 5-15 mL: 2-5 g: 2-6 g: 0.1-1: 0.1 g-0.5 g;

[0020] S2, adding acetone in an equal volume to the dichloromethane to the reaction system after the reaction, mixing, and separating the solid and the liquid to obtain a polyacrylic acid-polyethylene glycol complex;

[0021] S3. After mixing the polyacrylic acid-polyethylene glycol complex and the polyvinyl alcohol powder, add them into water at 80-90° C. to prepare a mixed solution with a polyvinyl alcohol concentration of 6-8wt%; cool the mixed solution to 40-50° C. and keep warm, ultrasonically oscillate at 80-120 kHz for 30-50 min, and then cool to room temperature to obtain a modified polyvinyl alcohol solution; wherein the mass ratio of the polyvinyl alcohol powder to the polyacrylic acid-polyethylene glycol complex is 5-7:1-3.

[0022] The present invention has at least the following beneficial effects:

[0023] (1) NZP-high entropy (Ln) prepared by the present invention 1 / n The )PO4 monazite-type composite ceramic solid body, on the one hand, utilizes the crystal structure characteristics of NZP and monazite that can solidify fission products and (minor) actinides respectively, and on the other hand, relying on the performance advantages of high-entropy ceramics, by combining the crystal structure characteristics of NZP and monazite with the performance advantages of high-entropy ceramics, can solve the deficiency of a single type of solid-dissolved radioactive nuclides in single-phase ceramics and achieve the purpose of simultaneously solidifying more than 5 kinds of fission products and (minor) actinides in HLW. In addition, the prepared solid body has excellent chemical stability and irradiation stability, which will have important scientific and practical significance for the ceramic high-inclusion solidification treatment of HLW with complex components.

[0024] (2) NZP-high entropy (Ln) prepared by the present invention 1 / n )PO4 monazite composite ceramic solid body, the high entropy (Ln 1 / n )PO4 monazite and the molar ratio of the two constituent phases, which is practical for the simultaneous solidification treatment of multiple fission products and (minor) actinide nuclides in HLW of different source phases.

[0025] (3) The present invention adopts an in-situ preparation process to obtain NZP-high entropy (Ln 1 / n )PO4 monazite composite ceramic solid body, achieving the composition phase Sr 0.5The synthesis of Zr2(PO4)3 and high-entropy monazite is sintered densely and integratedly, and it can achieve simultaneous and precise solidification of 5 or more fission products and (secondary) actinide nuclides, providing a simple, efficient and energy-saving preparation method for HLW treatment using ceramic solidification.

[0026] (4) NZP-high entropy (Ln) prepared by the present invention 1 / n )PO4 monazite composite ceramic solid body has high density, the raw materials required for preparing the solid body are easy to obtain, the preparation process is simple, the production cycle is short, the sintering temperature is low, and it is highly efficient and energy-saving, which is conducive to practical engineering application and promotion.

[0027] In summary, the NZP-high entropy (Ln 1 / n )PO4 monazite-type composite ceramic solid body composition design and in-situ preparation method, which has the advantages of flexible composition design, wide waste adaptability, simple preparation process, energy saving and high efficiency, high density of solid body, excellent performance, and the ability to simultaneously solidify fission products and multiple (minor) actinide nuclides.

[0028] At the same time, the present invention uses polyvinyl alcohol solution and modified polyvinyl alcohol solution as binders respectively during granulation, wherein the modified polyvinyl alcohol solution first uses polyethylene glycol-600 and polyacrylic acid to react to obtain a polyacrylic acid-polyethylene glycol complex, and then the polyacrylic acid-polyethylene glycol complex is mixed with polyvinyl alcohol for dispersion and blending, and the carboxylic acid group (-COOH) of polyacrylic acid (PAA) and the hydrophilic long chain of polyethylene glycol-600 (PEG-600) are combined by chemical bonds to form a complex, which can improve the dispersibility and rheological properties of the polyvinyl alcohol (PVA) solution. After the modified polyvinyl alcohol solution is used as a binder, the agglomeration of ceramic powder particles is effectively reduced, the uniform distribution of particles is promoted, the fluidity and dispersibility of the raw material powder are significantly improved, the fluidity of the slurry is enhanced, the particles are arranged more closely during the molding process, the porosity is reduced, and the NZP-high entropy (Ln 1 / n )Sintered bulk density and relative density of PO4 monazite composite ceramic solid body.

[0029] Other advantages, objectives and features of the present invention will be embodied in part through the following description, and in part will be understood by those skilled in the art through study and practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 0.5Sr prepared in Example 1 and Example 2 of the present invention 0.5 Zr2(PO4)3-0.5(Ln 1 / 5 )XRD pattern of PO4 composite ceramic solid body.

[0031] Figure 20.5Sr prepared in Examples 7 to 9 of the present invention 0.5 Zr2(PO4)3-0.5(Ln 1 / 6 )XRD pattern of PO4 composite ceramic solid body.

[0032] Figure 3 0.5Sr prepared in Examples 7 and 8 of the present invention 0.5 Zr2(PO4)3-0.5(Ln 1 / 6 )SEM image of PO4 composite ceramic solid body.

[0033] Figure 4 0.5Sr prepared in Example 7 of the present invention 0.5 Zr2(PO4)3-0.5(Ln 1 / 6 )EDS mapping of PO4 composite ceramic solid body.

[0034] Figure 5 0.5Sr prepared in Examples 7 to 9 of the present invention 0.5 Zr2(PO4)3-0.5(Ln 1 / 6 )The change of shrinkage rate and density of PO4 composite ceramic solid body.

[0035] Figure 6 The 0.5Sr prepared in Examples 4, 9 and 12 of the present invention 0.5 Zr2(PO4)3-0.5(Ln 1 / n )XRD pattern of PO4 composite ceramic solid body. DETAILED DESCRIPTION

[0036] The present invention is further described in detail below in conjunction with the accompanying drawings so that those skilled in the art can implement the invention with reference to the description.

[0037] It should be understood that the terms such as “having”, “including” and “comprising” used herein do not exclude the existence or addition of one or more other elements or combinations thereof.

[0038] Embodiment 1:

[0039] A NZP-high entropy (Ln 1 / 5 )PO4 monazite composite ceramic solid body, the chemical composition formula is (1-x)Sr 0.5 Zr2(PO4)3-x(La 1 / 5 Nd 1 / 5 Sm 1 / 5 Eu 1 / 5 G 1 / 5 )PO4, wherein x=0.5; the specific process flow comprises the following steps:

[0040] (1) Ingredients: Sr(NO3)2, ZrO2, NH4H2PO4, La2O3, Nd2O3, Sm2O3, Eu2O3, and Gd2O3 are used as raw materials and the ingredients are prepared according to the designed stoichiometric ratio.

[0041] (2) Mixing: The wet ball milling process is used to mix the raw materials in a planetary ball mill for 12 hours. After the mixture is evenly mixed, it is placed in an oven for drying. Zirconia balls are used as the ball milling medium, and anhydrous ethanol is used as the dispersant. The mass ratio of raw materials, zirconia balls, and alcohol is 1:2:1.75.

[0042] (3) Pretreatment: The dried powder is placed in a crucible and placed in a muffle furnace for pretreatment. The temperature is raised from room temperature to 600°C, kept at 600°C for 8 hours, and finally cooled naturally to room temperature.

[0043] (4) Secondary mixing: Add 1wt.% zinc oxide to the pretreated powder, and mill it in a planetary ball mill for 24 hours. After the mixture is evenly mixed, place it in an oven for drying. Zirconia balls are used as the milling medium, and anhydrous ethanol is used as the dispersant. The mass ratio of raw material: zirconium oxide balls: alcohol is 1:2:1.75.

[0044] (5) Granulation and aging: Add 7 wt.% of the total mass of the powder into the dried powder as a binder polyvinyl alcohol (PVA) solution (binder concentration is 6 wt.%) for granulation, and then age for 24 h.

[0045] (6) Molding and plastic removal: Isostatic pressing is used, the molding pressure is 200 MPa, and the holding time is 3 min. The molded green body is placed in a muffle furnace for plastic removal. The temperature is raised from room temperature to 700 °C, and kept at 700 °C for 1 h, and finally cooled naturally to room temperature.

[0046] (7) Sintering: The molded green body was placed in a microwave sintering furnace and heated to 1050°C at a rate of 5°C / min and kept at that temperature for 1.5 h to obtain 0.5Sr 0.5 Zr2(PO4)3-0.5(La 1 / 5 Nd 1 / 5 Sm 1 / 5 Eu 1 / 5 G 1 / 5 )PO4 composite ceramic solid body.

[0047] Embodiment 2:

[0048] A NZP-high entropy (Ln 1 / 5 )PO4 monazite composite ceramic solid body, the chemical composition formula is (1-x)Sr 0.5 Zr2(PO4)3-x(La 1 / 5 Nd1 / 5 Sm 1 / 5 Eu 1 / 5 G 1 / 5 )PO4, wherein x=0.5; the specific process flow comprises the following steps:

[0049] (1) Ingredients: Sr(NO3)2, ZrO2, NH4H2PO4, La2O3, Nd2O3, Sm2O3, Eu2O3, and Gd2O3 are used as raw materials and the ingredients are prepared according to the designed stoichiometric ratio.

[0050] (2) Mixing: The wet ball milling process was used to mix the raw materials in a planetary ball mill for 12 hours. After the mixture was evenly mixed, it was placed in an oven to dry at 60°C. Zirconia balls were used as the ball milling medium, and anhydrous ethanol was used as the dispersant. The mass ratio of raw materials: zirconium oxide balls: alcohol was 1:2:1.75.

[0051] (3) Pretreatment: The dried powder is placed in a crucible and then placed in a muffle furnace for pretreatment. The temperature is raised from room temperature to 600°C, kept at 600°C for 8 hours, and finally cooled naturally to room temperature.

[0052] (4) Secondary mixing: Add 1wt.% zinc oxide to the pretreated powder, and use a planetary ball mill for 24 hours to mix evenly and then place in an oven for drying. Zirconia balls are used as the ball milling medium, and anhydrous ethanol is used as the dispersant, wherein the mass ratio of raw material, zirconia balls, and alcohol is 1:2:1.75.

[0053] (5) Granulation and aging: Add 7 wt.% of the total mass of the powder to the dried powder (the binder concentration is 6 wt.%) for granulation, and then age for 24 hours.

[0054] (6) Molding and plastic removal: Isostatic pressing is used, the molding pressure is 200 MPa, and the holding time is 3 min. The molded green body is placed in a muffle furnace for plastic removal. The temperature is raised from room temperature to 700 °C, and kept at 700 °C for 1 h, and finally cooled naturally to room temperature.

[0055] (7) Sintering: The molded green body was placed in a microwave sintering furnace and heated to 1050°C at a rate of 5°C / min and kept at that temperature for 2 h to obtain 0.5Sr 0.5 Zr2(PO4)3-0.5(La 1 / 5 Nd 1 / 5 Sm 1 / 5 Eu 1 / 5 G 1 / 5 )PO4 composite ceramic solid body.

[0056] Embodiment 3:

[0057] A NZP-high entropy (Ln1 / 5 )PO4 monazite composite ceramic solid body, the chemical composition formula is (1-x)Sr 0.5 Zr2(PO4)3-x(La 1 / 5 Nd 1 / 5 Sm 1 / 5 Eu 1 / 5 G 1 / 5 )PO4, wherein x=0.5; the specific process flow comprises the following steps:

[0058] (1) Ingredients: Sr(NO3)2, ZrO2, NH4H2PO4, La2O3, Nd2O3, Sm2O3, Eu2O3, and Gd2O3 are used as raw materials and the ingredients are prepared according to the designed stoichiometric ratio.

[0059] (2) Mixing: The wet ball milling process was used to mix the raw materials in a planetary ball mill for 12 hours. After the mixture was evenly mixed, it was placed in an oven for drying. Zirconia balls were used as the ball milling medium, and anhydrous ethanol was used as the dispersant. The mass ratio of raw materials: zirconium oxide balls: alcohol was 1:2:1.75.

[0060] (3) Pretreatment: The dried powder is placed in a crucible and placed in a muffle furnace for pretreatment. The temperature is raised from room temperature to 600°C, kept at 600°C for 8 hours, and finally cooled naturally to room temperature.

[0061] (4) Secondary mixing: Add 1wt.% zinc oxide to the pretreated powder, and use a planetary ball mill for 24 hours to mix evenly and then place in an oven for drying. Zirconia balls are used as the ball milling medium, and anhydrous ethanol is used as the dispersant, wherein the mass ratio of raw material, zirconia balls, and alcohol is 1:2:1.75.

[0062] (5) Granulation and aging: Add 7 wt.% of the total mass of the powder to the dried powder (the binder concentration is 6 wt.%) for granulation, and then age for 24 hours.

[0063] (6) Molding and plastic removal: Isostatic pressing is used, the molding pressure is 200 MPa, and the holding time is 3 min. The molded green body is placed in a muffle furnace for plastic removal. The temperature is raised from room temperature to 700 °C, and kept at 700 °C for 1 h, and finally cooled naturally to room temperature.

[0064] (7) Sintering: The molded green body was placed in a microwave sintering furnace and heated to 1100°C at a rate of 5°C / min and kept at that temperature for 2 h to obtain 0.5Sr 0.5 Zr2(PO4)3-0.5(La 1 / 5 Nd 1 / 5 Sm 1 / 5 Eu 1 / 5 G 1 / 5)PO4 composite ceramic solid body.

[0065] Embodiment 4:

[0066] A NZP-high entropy (Ln 1 / 5 )PO4 monazite composite ceramic solid body, the chemical composition formula is (1-x)Sr 0.5 Zr2(PO4)3-x(La 1 / 5 Nd 1 / 5 Sm 1 / 5 Eu 1 / 5 G 1 / 5 )PO4, wherein x=0.5; the specific process flow comprises the following steps:

[0067] (1) Ingredients: Sr(NO3)2, ZrO2, NH4H2PO4, La2O3, Nd2O3, Sm2O3, Eu2O3, and Gd2O3 are used as raw materials and the ingredients are prepared according to the designed stoichiometric ratio.

[0068] (2) Mixing: The wet ball milling process is used to mix the raw materials in a planetary ball mill for 12 hours. After the mixture is evenly mixed, it is placed in an oven for drying. Zirconia balls are used as the ball milling medium, and anhydrous ethanol is used as the dispersant. The mass ratio of raw materials, zirconia balls, and alcohol is 1:2:1.75.

[0069] (3) Pretreatment: The dried powder is placed in a crucible and placed in a muffle furnace for pretreatment. The temperature is raised from room temperature to 600°C, kept at 600°C for 8 hours, and finally cooled naturally to room temperature.

[0070] (4) Secondary mixing: Add 1wt.% zinc oxide to the pretreated powder, and mill it in a planetary ball mill for 24 hours. After the mixture is evenly mixed, place it in an oven for drying. Zirconia balls are used as the milling medium, and anhydrous ethanol is used as the dispersant. The mass ratio of raw materials, zirconium oxide balls, and alcohol is 1:2:1.75.

[0071] (5) Granulation and aging: Add 7 wt.% of the total mass of the powder to the dried powder (the binder concentration is 6 wt.%) for granulation, and then age for 24 hours.

[0072] (6) Molding and plastic removal: Isostatic pressing is used, the molding pressure is 200 MPa, and the holding time is 3 min. The molded green body is placed in a muffle furnace for plastic removal. The temperature is raised from room temperature to 700 °C, and kept at 700 °C for 1 h, and finally cooled naturally to room temperature.

[0073] (7) Sintering: The molded green body was placed in a microwave sintering furnace and heated to 1150°C at a rate of 5°C / min and kept at that temperature for 2 h to obtain 0.5Sr 0.5Zr2(PO4)3-0.5(La 1 / 5 Nd 1 / 5 Sm 1 / 5 Eu 1 / 5 G 1 / 5 )PO4 composite ceramic solid body.

[0074] Embodiment 5:

[0075] A NZP-high entropy (Ln 1 / 5 )PO4 monazite composite ceramic solid body, the chemical composition formula is (1-x)Sr 0.5 Zr2(PO4)3-x(La 1 / 5 Nd 1 / 5 Sm 1 / 5 Eu 1 / 5 G 1 / 5 )PO4, wherein x=0.2; the specific process flow comprises the following steps:

[0076] (1) Ingredients: Sr(NO3)2, ZrO2, NH4H2PO4, La2O3, Nd2O3, Sm2O3, Eu2O3, and Gd2O3 are used as raw materials and the ingredients are prepared according to the designed stoichiometric ratio.

[0077] (2) Mixing: The wet ball milling process was used to mix the raw materials in a planetary ball mill for 12 hours. After the mixture was evenly mixed, it was placed in an oven to dry at 60°C. Zirconia balls were used as the ball milling medium, and anhydrous ethanol was used as the dispersant. The mass ratio of raw materials, zirconia balls, and alcohol was 1:2:1.75.

[0078] (3) Pretreatment: The dried powder is placed in a crucible and then placed in a muffle furnace for pretreatment. The temperature is raised from room temperature to 600°C, kept at 600°C for 8 hours, and finally cooled naturally to room temperature.

[0079] (4) Secondary mixing: Add 1wt.% zinc oxide to the pretreated powder, and use a planetary ball mill for 24 hours to mix evenly and then place in an oven for drying. Zirconia balls are used as the ball milling medium, and anhydrous ethanol is used as the dispersant, wherein the mass ratio of raw material, zirconia balls, and alcohol is 1:2:1.75.

[0080] (5) Granulation and aging: Add 7 wt.% of the total mass of the powder to the dried powder (the binder concentration is 6 wt.%) for granulation, and then age for 24 hours.

[0081] (6) Molding and plastic removal: Isostatic pressing is used, the molding pressure is 200 MPa, and the holding time is 3 min. The molded green body is placed in a muffle furnace for plastic removal. The temperature is raised from room temperature to 700 °C, and kept at 700 °C for 1 h, and finally cooled naturally to room temperature.

[0082] (7) Sintering: The molded green body was placed in a microwave sintering furnace and heated to 1050°C at a rate of 5°C / min and kept at that temperature for 2 h to obtain 0.8Sr 0.5 Zr2(PO4)3-0.2(La 1 / 5 Nd 1 / 5 Sm 1 / 5 Eu 1 / 5 G 1 / 5 )PO4 composite ceramic solid body.

[0083] Embodiment 6:

[0084] A NZP-high entropy (Ln 1 / 5 )PO4 monazite composite ceramic solid body, the chemical composition formula is (1-x)Sr 0.5 Zr2(PO4)3-x(La 1 / 5 Nd 1 / 5 Sm 1 / 5 Eu 1 / 5 G 1 / 5 )PO4, wherein x=0.8; the specific process flow comprises the following steps:

[0085] (1) Ingredients: Sr(NO3)2, ZrO2, NH4H2PO4, La2O3, Nd2O3, Sm2O3, Eu2O3, and Gd2O3 are used as raw materials and the ingredients are prepared according to the designed stoichiometric ratio.

[0086] (2) Mixing: The wet ball milling process was used to mix the raw materials in a planetary ball mill for 12 hours. After the mixture was evenly mixed, it was placed in an oven to dry at 60°C. Zirconia balls were used as the ball milling medium, and anhydrous ethanol was used as the dispersant. The mass ratio of raw materials, zirconia balls, and alcohol was 1:2:1.75.

[0087] (3) Pretreatment: The dried powder is placed in a crucible and then placed in a muffle furnace for pretreatment. The temperature is raised from room temperature to 600°C, kept at 600°C for 8 hours, and finally cooled naturally to room temperature.

[0088] (4) Secondary mixing: Add 1wt.% zinc oxide to the pretreated powder, and mill it in a planetary ball mill for 24 hours. After the mixture is evenly mixed, place it in an oven for drying. Zirconia balls are used as the milling medium, and anhydrous ethanol is used as the dispersant. The mass ratio of raw materials, zirconium oxide balls, and alcohol is 1:2:1.75.

[0089] (5) Granulation and aging: Add 7 wt.% of the total mass of the powder to the dried powder (the binder concentration is 6 wt.%) for granulation, and then age for 24 hours.

[0090] (6) Molding and plastic removal: Isostatic pressing is used, the molding pressure is 200 MPa, and the holding time is 3 min. The molded green body is placed in a muffle furnace for plastic removal. The temperature is raised from room temperature to 700 °C, and kept at 700 °C for 1 h, and finally cooled naturally to room temperature.

[0091] (7) Sintering: The molded green body was placed in a microwave sintering furnace and heated to 1050°C at a rate of 5°C / min and kept at that temperature for 2 h to obtain 0.2Sr 0.5 Zr2(PO4)3-0.8(La 1 / 5 Nd 1 / 5 Sm 1 / 5 Eu 1 / 5 G 1 / 5 )PO4 composite ceramic solid body.

[0092] Embodiment 7:

[0093] A NZP-high entropy (Ln 1 / 6 )PO4 monazite composite ceramic solid body, the chemical composition formula is (1-x)Sr 0.5 Zr2(PO4)3-x(La 1 / 6 Nd 1 / 6 Sm 1 / 6 Eu 1 / 6 G 1 / 6 Ho 1 / 6 )PO4, wherein x=0.5; the specific process flow comprises the following steps:

[0094] (1) Ingredients: Sr(NO3)2, ZrO2, NH4H2PO4, La2O3, Nd2O3, Sm2O3, Eu2O3, Gd2O3, Ho2O3 are used as raw materials and the ingredients are prepared according to the designed stoichiometric ratio.

[0095] (2) Mixing: The wet ball milling process is used to mix the raw materials in a planetary ball mill for 12 hours. After the mixture is evenly mixed, it is placed in an oven for drying. Zirconia balls are used as the ball milling medium, and anhydrous ethanol is used as the dispersant. The mass ratio of raw materials, zirconia balls, and alcohol is 1:2:1.75.

[0096] (3) Pretreatment: The dried powder is placed in a crucible and placed in a muffle furnace for pretreatment. The temperature is raised from room temperature to 600°C, kept at 600°C for 8 hours, and finally cooled naturally to room temperature.

[0097] (4) Secondary mixing: Add 1wt.% zinc oxide to the pretreated powder, and use a planetary ball mill for 24 hours to mix evenly and then place in an oven for drying. Zirconia balls are used as the ball milling medium, and anhydrous ethanol is used as the dispersant, wherein the mass ratio of raw material, zirconia balls, and alcohol is 1:2:1.75.

[0098] (5) Granulation and aging: Add 7 wt.% of the total mass of the powder to the dried powder (the binder concentration is 6 wt.%) for granulation, and then age for 24 hours.

[0099] (6) Molding and plastic removal: Isostatic pressing is used, the molding pressure is 200 MPa, and the holding time is 3 min. The molded green body is placed in a muffle furnace for plastic removal. The temperature is raised from room temperature to 700 °C, and kept at 700 °C for 1 h, and finally cooled naturally to room temperature.

[0100] (7) Sintering: The molded green body was placed in a microwave sintering furnace and heated to 1050°C at a rate of 5°C / min and kept at that temperature for 2 h to obtain 0.5Sr 0.5 Zr2(PO4)3-0.5(La 1 / 6 Nd 1 / 6 Sm 1 / 6 Eu 1 / 6 G 1 / 6 Ho 1 / 6 )PO4 composite ceramic solid body.

[0101] Embodiment 8:

[0102] A NZP-high entropy (Ln 1 / 6 )PO4 monazite composite ceramic solid body, the chemical composition formula is (1-x)Sr 0.5 Zr2(PO4)3-x(La 1 / 6 Nd 1 / 6 Sm 1 / 6 Eu 1 / 6 G 1 / 6 Ho 1 / 6 )PO4, wherein x=0.5; the specific process flow comprises the following steps:

[0103] (1) Ingredients: Sr(NO3)2, ZrO2, NH4H2PO4, La2O3, Nd2O3, Sm2O3, Eu2O3, Gd2O3, Ho2O3 are used as raw materials and the ingredients are prepared according to the designed stoichiometric ratio.

[0104] (2) Mixing: The wet ball milling process was used to mix the raw materials in a planetary ball mill for 12 hours. After the mixture was evenly mixed, it was placed in an oven for drying. Zirconia balls were used as the ball milling medium, and anhydrous ethanol was used as the dispersant. The mass ratio of raw materials: zirconium oxide balls: alcohol was 1:2:1.75.

[0105] (3) Pretreatment: The dried powder is placed in a crucible and placed in a muffle furnace for pretreatment. The temperature is raised from room temperature to 600°C, kept at 600°C for 8 hours, and finally cooled naturally to room temperature.

[0106] (4) Secondary mixing: Add 1wt.% zinc oxide to the pretreated powder, and mill it in a planetary ball mill for 24 hours. After the mixture is evenly mixed, place it in an oven for drying. Zirconia balls are used as the milling medium, and anhydrous ethanol is used as the dispersant. The mass ratio of raw material: zirconium oxide balls: alcohol is 1:2:1.75.

[0107] (5) Granulation and aging: Add 7 wt.% of the total mass of the powder to the dried powder (the binder concentration is 6 wt.%) for granulation, and then age for 24 hours.

[0108] (6) Molding and plastic removal: Isostatic pressing is used, the molding pressure is 200 MPa, and the holding time is 3 min. The molded green body is placed in a muffle furnace for plastic removal. The temperature is raised from room temperature to 700 °C, and kept at 700 °C for 1 h, and finally cooled naturally to room temperature.

[0109] (7) Sintering: The molded green body was placed in a microwave sintering furnace and heated to 1100°C at a rate of 5°C / min and kept at that temperature for 2 h to obtain 0.5Sr 0.5 Zr2(PO4)3-0.5(La 1 / 6 Nd 1 / 6 Sm 1 / 6 Eu 1 / 6 G 1 / 6 Ho 1 / 6 )PO4 composite ceramics.

[0110] Embodiment 9:

[0111] A NZP-high entropy (Ln 1 / 6 )PO4 monazite composite ceramic solid body, the chemical composition formula is (1-x)Sr 0.5 Zr2(PO4)3-x(La 1 / 6 Nd 1 / 6 Sm 1 / 6 Eu 1 / 6 G 1 / 6 Ho 1 / 6 )PO4, wherein x=0.5; the specific process flow comprises the following steps:

[0112] (1) Ingredients: Sr(NO3)2, ZrO2, NH4H2PO4, La2O3, Nd2O3, Sm2O3, Eu2O3, Gd2O3, Ho2O3 are used as raw materials and the ingredients are prepared according to the designed stoichiometric ratio.

[0113] (2) Mixing: The wet ball milling process is used to mix the raw materials in a planetary ball mill for 12 hours. After the mixture is evenly mixed, it is placed in an oven for drying. Zirconia balls are used as the ball milling medium, and anhydrous ethanol is used as the dispersant. The mass ratio of raw materials, zirconia balls, and alcohol is 1:2:1.75.

[0114] (3) Pretreatment: The dried powder is placed in a crucible and placed in a muffle furnace for pretreatment. The temperature is raised from room temperature to 600°C, kept at 600°C for 8 hours, and finally cooled naturally to room temperature.

[0115] (4) Secondary mixing: Add 1wt.% zinc oxide to the pretreated powder, and use a planetary ball mill for 24 hours to mix evenly and then place in an oven for drying. Zirconia balls are used as the ball milling medium, and anhydrous ethanol is used as the dispersant, wherein the mass ratio of raw material, zirconia balls, and alcohol is 1:2:1.75.

[0116] (5) Granulation and aging: Add 7 wt.% of the total mass of the powder to the dried powder (the binder concentration is 6 wt.%) for granulation, and then age for 24 hours.

[0117] (6) Molding and plastic removal: Isostatic pressing is used, the molding pressure is 200 MPa, and the holding time is 3 min. The molded green body is placed in a muffle furnace for plastic removal. The temperature is raised from room temperature to 700 °C, and kept at 700 °C for 1 h, and finally cooled naturally to room temperature.

[0118] (7) Sintering: The molded green body was placed in a microwave sintering furnace and heated to 1150°C at a rate of 5°C / min and kept at that temperature for 2 h to obtain 0.5Sr 0.5 Zr2(PO4)3-0.5(La 1 / 6 Nd 1 / 6 Sm 1 / 6 Eu 1 / 6 G 1 / 6 Ho 1 / 6 )PO4 composite ceramic solid body.

[0119] Embodiment 10:

[0120] A NZP-high entropy (Ln 1 / 6 )PO4 monazite composite ceramic solid body, the chemical composition formula is (1-x)Sr 0.5 Zr2(PO4)3-x(La 1 / 6 Nd 1 / 6 Sm 1 / 6 Eu 1 / 6 G 1 / 6 Ho 1 / 6 )PO4, wherein x=0.5; the specific process flow comprises the following steps:

[0121] (1) Ingredients: Sr(NO3)2, ZrO2, NH4H2PO4, La2O3, Nd2O3, Sm2O3, Eu2O3, Gd2O3, Ho2O3 are used as raw materials and the ingredients are prepared according to the designed stoichiometric ratio.

[0122] (2) Mixing: The wet ball milling process is used to mix the raw materials in a planetary ball mill for 12 hours. After the mixture is evenly mixed, it is placed in an oven for drying. Zirconia balls are used as the ball milling medium, and anhydrous ethanol is used as the dispersant. The mass ratio of raw materials, zirconia balls, and alcohol is 1:2:1.75.

[0123] (3) Pretreatment: The dried powder is placed in a crucible and placed in a muffle furnace for pretreatment. The temperature is raised from room temperature to 600°C, kept at 600°C for 8 hours, and finally cooled naturally to room temperature.

[0124] (4) Secondary mixing: Add 1wt.% zinc oxide to the pretreated powder, and use a planetary ball mill for 24 hours to mix evenly and then place in an oven for drying. Zirconia balls are used as the ball milling medium, and anhydrous ethanol is used as the dispersant, wherein the mass ratio of raw material, zirconia balls, and alcohol is 1:2:1.75.

[0125] (5) Granulation and aging: Add 7 wt.% of the total mass of the powder to the dried powder (the binder concentration is 6 wt.%) for granulation, and then age for 24 hours.

[0126] (6) Molding and plastic removal: Isostatic pressing is used, the molding pressure is 200 MPa, and the holding time is 3 min. The molded green body is placed in a muffle furnace for plastic removal. The temperature is raised from room temperature to 700 °C, and kept at 700 °C for 1 h, and finally cooled naturally to room temperature.

[0127] (7) Sintering: The molded green body was placed in a muffle furnace and heated to 1150°C at a rate of 5°C / min and kept at that temperature for 2 h to obtain 0.5Sr 0.5 Zr2(PO4)3-0.5(La 1 / 6 Nd 1 / 6 Sm 1 / 6 Eu 1 / 6 G 1 / 6 Ho 1 / 6 )PO4 composite ceramic solid body.

[0128] Embodiment 11:

[0129] A NZP-high entropy (Ln 1 / 6 )PO4 monazite composite ceramic solid body, the chemical composition formula is (1-x)Sr 0.5 Zr2(PO4)3-x(La 1 / 6 Nd 1 / 6 Sm 1 / 6 Eu 1 / 6 G 1 / 6 Ho 1 / 6)PO4, wherein x=0.5; the specific process flow comprises the following steps:

[0130] (1) Ingredients: Sr(NO3)2, ZrO2, NH4H2PO4, La2O3, Nd2O3, Sm2O3, Eu2O3, Gd2O3, Ho2O3 are used as raw materials and the ingredients are prepared according to the designed stoichiometric ratio.

[0131] (2) Mixing: The wet ball milling process is used to mix the raw materials in a planetary ball mill for 12 hours. After the mixture is evenly mixed, it is placed in an oven for drying. Zirconia balls are used as the ball milling medium, and anhydrous ethanol is used as the dispersant. The mass ratio of raw materials, zirconia balls, and alcohol is 1:2:1.75.

[0132] (3) Pretreatment: The dried powder is placed in a crucible and placed in a muffle furnace for pretreatment. The temperature is raised from room temperature to 600°C, kept at 600°C for 8 hours, and finally cooled naturally to room temperature.

[0133] (4) Secondary mixing: Add 1wt.% zinc oxide to the pretreated powder, and use a planetary ball mill for 24 hours to mix evenly and then place in an oven for drying. Zirconia balls are used as the ball milling medium, and anhydrous ethanol is used as the dispersant, wherein the mass ratio of raw material, zirconia balls, and alcohol is 1:2:1.75.

[0134] (5) Granulation and aging: Add 7 wt.% of the total mass of the powder to the dried powder (the binder concentration is 6 wt.%) for granulation, and then age for 24 hours.

[0135] (6) Molding and plastic removal: Dry pressing is used, the molding pressure is 200 MPa, and the holding time is 3 min. The molded green body is placed in a muffle furnace for plastic removal. The temperature is raised from room temperature to 700 °C, and kept at 700 °C for 1 h, and finally cooled naturally to room temperature.

[0136] (7) Sintering: The molded green body was placed in a muffle furnace and heated to 1150°C at a rate of 5°C / min and kept at that temperature for 2 h to obtain 0.5Sr 0.5 Zr2(PO4)3-0.5(La 1 / 6 Nd 1 / 6 Sm 1 / 6 Eu 1 / 6 G 1 / 6 Ho 1 / 6 )PO4 composite ceramic solid body.

[0137] Embodiment 12:

[0138] A NZP-high entropy (Ln 1 / 7 )PO4 monazite composite ceramic solid body, the chemical composition formula is (1-x)Sr0.5 Zr2(PO4)3-x(La 1 / 7 Nd 1 / 7 Sm 1 / 7 Eu 1 / 7 G 1 / 7 Ho 1 / 7 Er 1 / 7 )PO4, wherein x=0.5; the specific process flow comprises the following steps:

[0139] (1) Ingredients: Sr(NO3)2, ZrO2, NH4H2PO4, La2O3, Nd2O3, Sm2O3, Eu2O3, Gd2O3, Ho2O3, Er2O3 are used as raw materials and the ingredients are prepared according to the designed stoichiometric ratio.

[0140] (2) Mixing: The wet ball milling process is used to mix the raw materials in a planetary ball mill for 12 hours. After the mixture is evenly mixed, it is placed in an oven for drying. Zirconia balls are used as the ball milling medium, and anhydrous ethanol is used as the dispersant. The mass ratio of raw materials, zirconia balls, and alcohol is 1:2:1.75.

[0141] (3) Pretreatment: The dried powder is placed in a crucible and placed in a muffle furnace for pretreatment. The temperature is raised from room temperature to 600°C, kept at 600°C for 8 hours, and finally cooled naturally to room temperature.

[0142] (4) Secondary mixing: Add 1wt.% zinc oxide to the pretreated powder, and use a planetary ball mill for 24 hours to mix evenly and then place in an oven for drying. Zirconia balls are used as the ball milling medium, and anhydrous ethanol is used as the dispersant, wherein the mass ratio of raw material, zirconia balls, and alcohol is 1:2:1.75.

[0143] (5) Granulation and aging: Add 7 wt.% of the total mass of the powder to the dried powder (the binder concentration is 6 wt.%) for granulation, and then age for 24 hours.

[0144] (6) Molding and plastic removal: Isostatic pressing is used, the molding pressure is 200 MPa, and the holding time is 3 min. The molded green body is placed in a muffle furnace for plastic removal. The temperature is raised from room temperature to 700 °C, and kept at 700 °C for 1 h, and finally cooled naturally to room temperature.

[0145] (7) Sintering: The molded green body was placed in a microwave sintering furnace and heated to 1150°C at a rate of 5°C / min and kept at that temperature for 2 h to obtain 0.5Sr 0.5 Zr2(PO4)3-0.5(La 1 / 7 Nd 1 / 7 Sm 1 / 7 Eu 1 / 7 G 1 / 7 Ho1 / 7 Er 1 / 7 )PO4 composite ceramic solid body.

[0146] Embodiment 13:

[0147] A NZP-high entropy (Ln 1 / 7 )PO4 monazite composite ceramic solid body, the chemical composition formula is (1-x)Sr 0.5 Zr2(PO4)3-x(La 1 / 7 Nd 1 / 7 Sm 1 / 7 Eu 1 / 7 G 1 / 7 Ho 1 / 7 Er 1 / 7 )PO4, wherein x=0.5; the specific process flow comprises the following steps:

[0148] (1) Ingredients: Sr(NO3)2, ZrO2, NH4H2PO4, La2O3, Nd2O3, Sm2O3, Eu2O3, Gd2O3, Ho2O3, Er2O3 are used as raw materials and the ingredients are prepared according to the designed stoichiometric ratio.

[0149] (2) Mixing: The wet ball milling process is used to mix the raw materials in a planetary ball mill for 12 hours. After the mixture is evenly mixed, it is placed in an oven for drying. Zirconia balls are used as the ball milling medium, and anhydrous ethanol is used as the dispersant. The mass ratio of raw materials, zirconia balls, and alcohol is 1:2:1.75.

[0150] (3) Pretreatment: The dried powder is placed in a crucible and placed in a muffle furnace for pretreatment. The temperature is raised from room temperature to 600°C, kept at 600°C for 8 hours, and finally cooled naturally to room temperature.

[0151] (4) Secondary mixing: Add 1wt.% zinc oxide to the pretreated powder, and use a planetary ball mill for 24 hours to mix evenly and then place in an oven for drying. Zirconia balls are used as the ball milling medium, and anhydrous ethanol is used as the dispersant, wherein the mass ratio of raw material, zirconia balls, and alcohol is 1:2:1.75.

[0152] (5) Granulation and aging: Add 7 wt.% of the total mass of the powder to the dried powder (the binder concentration is 6 wt.%) for granulation, and then age for 24 hours.

[0153] (6) Molding and plastic removal: Isostatic pressing is used, the molding pressure is 200 MPa, and the holding time is 3 min. The molded green body is placed in a muffle furnace for plastic removal. The temperature is raised from room temperature to 700 °C, and kept at 700 °C for 1 h, and finally cooled naturally to room temperature.

[0154] (7) Sintering: The molded green body was placed in a microwave sintering furnace and heated to 1200°C at a rate of 5°C / min and kept at that temperature for 2 h to obtain 0.5Sr 0.5 Zr2(PO4)3-0.5(La 1 / 7 Nd 1 / 7 Sm 1 / 7 Eu 1 / 7 G 1 / 7 Ho 1 / 7 Er 1 / 7 )PO4 composite ceramic solid body.

[0155] Embodiment 14:

[0156] A NZP-high entropy (Ln 1 / 7 )PO4 monazite composite ceramic solid body, the chemical composition formula is (1-x)Sr 0.5 Zr2(PO4)3-x(La 1 / 7 Nd 1 / 7 Sm 1 / 7 Eu 1 / 7 G 1 / 7 Ho 1 / 7 Er 1 / 7 )PO4, wherein x=0.5; the specific process flow comprises the following steps:

[0157] (1) Ingredients: Sr(NO3)2, ZrO2, NH4H2PO4, La2O3, Nd2O3, Sm2O3, Eu2O3, Gd2O3, Ho2O3, Er2O3 are used as raw materials and the ingredients are prepared according to the designed stoichiometric ratio.

[0158] (2) Mixing: The wet ball milling process is used to mix the raw materials in a planetary ball mill for 12 hours. After the mixture is evenly mixed, it is placed in an oven for drying. Zirconia balls are used as the ball milling medium, and anhydrous ethanol is used as the dispersant. The mass ratio of raw materials, zirconia balls, and alcohol is 1:2:1.75.

[0159] (3) Pretreatment: The dried powder is placed in a crucible and placed in a muffle furnace for pretreatment. The temperature is raised from room temperature to 600°C, kept at 600°C for 8 hours, and finally cooled naturally to room temperature.

[0160] (4) Secondary mixing: Add 1wt.% zinc oxide to the pretreated powder, and use a planetary ball mill for 24 hours to mix evenly and then place in an oven for drying. Zirconia balls are used as the ball milling medium, and anhydrous ethanol is used as the dispersant, wherein the mass ratio of raw material, zirconia balls, and alcohol is 1:2:1.75.

[0161] (5) Granulation and aging: Add 7 wt.% of the total mass of the powder to the dried powder (the binder concentration is 6 wt.%) for granulation, and then age for 24 hours.

[0162] (6) Molding and plastic removal: Isostatic pressing is used, the molding pressure is 200 MPa, and the holding time is 3 min. The molded green body is placed in a muffle furnace for plastic removal. The temperature is raised from room temperature to 700 °C, and kept at 700 °C for 1 h, and finally cooled naturally to room temperature.

[0163] (7) Sintering: The molded green body was placed in a microwave sintering furnace and heated to 1250°C at a rate of 5°C / min and kept at that temperature for 2 h to obtain 0.5Sr 0.5 Zr2(PO4)3-0.5(La 1 / 7 Nd 1 / 7 Sm 1 / 7 Eu 1 / 7 G 1 / 7 Ho 1 / 7 Er 1 / 7 )PO4 composite ceramic solid body.

[0164] Embodiment 15:

[0165] A NZP-high entropy (Ln 1 / 6 )PO4 monazite composite ceramic solid body, the chemical composition formula is (1-x)Sr 0.5 Zr2(PO4)3-x(La 1 / 6 Nd 1 / 6 Sm 1 / 6 Eu 1 / 6 G 1 / 6 Ho 1 / 6 )PO4, wherein x=0.5; the difference between this embodiment and embodiment 7 is that during granulation in this embodiment, a modified polyvinyl alcohol solution of equal mass is used to replace the polyvinyl alcohol solution; wherein the preparation method of the modified polyvinyl alcohol solution comprises:

[0166] S1. Using 150 mL of dichloromethane as solvent, mix 50 g of polyacrylic acid and 60 g of polyethylene glycol in the solvent, add 2 g of dicyclohexylcarbodiimide and 3 g of 2,6-lutidine, stir and mix, and heat in a water bath to 60°C for reaction. The reaction time is 24 h.

[0167] S2, adding acetone in an equal volume to the dichloromethane to the reaction system after the reaction, mixing, and separating the solid and the liquid to obtain a polyacrylic acid-polyethylene glycol complex;

[0168] S3. After mixing 1 g of polyacrylic acid-polyethylene glycol complex with 5 g of polyvinyl alcohol powder, add 94 mL of 90° C. water to obtain a mixed solution with a total concentration of polyacrylic acid-polyethylene glycol complex and polyvinyl alcohol of 6 wt %; cool the mixed solution to 50° C. and keep warm, ultrasonically oscillate at 120 kHz for 40 min, and then cool to room temperature to obtain a modified polyvinyl alcohol solution.

[0169] The methods and process parameters of the remaining steps of this embodiment are the same as those of Embodiment 7.

[0170] The NZP-high entropy (Ln 1 / n The specific chemical composition and main preparation process parameters of )PO4 composite ceramics are shown in Table 1.

[0171] Table 1 NZP-High Entropy (Ln 1 / 5 Chemical composition and main preparation process parameters of PO4 monazite composite ceramic solidification body

[0172]

[0173]

[0174] The above typical embodiments were tested by XRD, SEM, shrinkage, density and element distribution. The specific results are shown in Figure 1 to Figure 6 , Figure 1 , Figure 2 and Figure 5 The REE in is Ln. Figure 1 0.5Sr prepared in Example 1 and Example 2 respectively 0.5 Zr2(PO4)3-0.5(Ln 1 / 5 )PO4 composite ceramic solid body XRD spectrum. As shown in the figure, 0.5Sr prepared at 1050℃ for different time 0.5 Zr2(PO4)3-0.5(Ln 1 / 5 The XRD patterns of the PO4 composite ceramics are well matched with the corresponding phase standard cards, and the diffraction peaks are sharp, indicating that the phase composition contains only Sr 0.5 Zr2(PO4)3 and monazite crystal phases, and the crystallinity of the phase is relatively high.

[0175] Figure 2 0.5Sr as described in Examples 7 to 9 0.5 Zr2(PO4)3-0.5(Ln 1 / 6 ) XRD spectrum of PO4 composite ceramic solid. It was found that composite ceramic solid with expected phase composition could be successfully prepared at different sintering temperatures (1050~1150℃). Figure 3 0.5Sr prepared as described in Examples 7 and 80.5 Zr2(PO4)3-0.5(Ln 1 / 6 )PO4 composite ceramic solid body SEM image. It can be seen that the sample has high density and the two phases are evenly distributed. And from the EDSmapping image of the solid body sample of Example 7, it can also be seen that the element composition in the sample is evenly distributed (see Figure 4 ).in addition, Figure 5 0.5Sr prepared as described in Examples 7 to 9 0.5 Zr2(PO4)3-0.5(Ln 1 / 6 )PO4 composite ceramic solid body shrinkage, volume density and relative density change trend diagram. As shown in the figure, 0.5Sr prepared at different sintering temperatures 0.5 Zr2(PO4)3-0.5(Ln 1 / 6 )PO4 composite ceramics have high density, and the relative density is higher than 97%; among them, the NZP-high entropy (Ln 1 / 6 )PO4 monazite composite ceramic solid body, its volume density is 4.61g / cm 3 The relative density reached 98.65%, which is significantly higher than 3.75 g / cm in Example 7. 3 and 97.49%.

[0176] Figure 6 0.5Sr as described in Examples 4, 9 and 12 0.5 Zr2(PO4)3-0.5(Ln 1 / n )PO4 composite ceramic solid body. It can be seen that by changing the element type (n) of the solid body and keeping it at 1150℃ for 2h, 0.5Sr can be successfully prepared. 0.5 Zr2(PO4)3-0.5(Ln 1 / n )PO4 composite ceramic solid body, the sample phase composition only contains Sr 0.5 Zr2(PO4)3 and monazite crystal phases, and the crystallinity of the phase is relatively high.

[0177] The number of devices and processing scales described here are used to simplify the description of the present invention. Applications, modifications and variations of the present invention will be obvious to those skilled in the art.

[0178] Although the embodiments of the present invention have been disclosed as above, they are not limited to the applications listed in the specification and the implementation modes, and 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 the illustrations shown and described herein.

Claims

1. A NZP-high entropy (Ln 1 / n )PO4 monazite type composite ceramic solid body, characterized in that: The NZP-high entropy (Ln 1 / n The chemical formula of the solidified composite ceramic body of )PO4 monazite is: (1-x)Sr 0.5 Zr2(PO4)3-x(Ln 1 / n )PO4, where x represents the molar percentage, ranging from 0.1 to 0.9; n represents the high entropy (Ln 1 / n )PO4 monazite type Ln lattice element number, n is an integer and 5≤n≤7; at the same time, the Ln element types include La, Nd, Sm, Eu, Gd, Ho, Er, Sr in the composite ceramic solid body 0.5 Zr2(PO4)3 and (Ln 1 / n )PO4 molar ratio can be adjusted arbitrarily.

2. NZP-high entropy (Ln) as claimed in claim 1 1 / n )PO4 monazite type composite ceramic solid body, characterized in that: When n is 5, Ln 1 / 5 =La 1 / 5 Nd 1 / 5 Sm 1 / 5 Eu 1 / 5 G 1 / 5 ; When n is 6, Ln 1 / 6 =La 1 / 6 Nd 1 / 6 Sm 1 / 6 Eu 1 / 6 G 1 / 6 Ho 1 / 6 ; When n is 7, Ln 1 / 7 =La 1 / 7 Nd 1 / 7 Sm 1 / 7 Eu 1 / 7 G 1 / 7 Ho 1 / 7 Er 1 / 7 .

3. NZP-high entropy (Ln) as claimed in claim 1 1 / n )PO4 monazite type composite ceramic solid body, characterized in that: The NZP-high entropy (Ln 1 / n The crystal phase composition of the PO4 monazite composite ceramic solid body contains only Sr 0.5 Zr2(PO4)3 and (Ln 1 / n )PO4 two crystal phases.

4. NZP-high entropy (Ln) as claimed in claim 1 1 / n )PO4 monazite type composite ceramic solid body, characterized in that: The NZP-high entropy (Ln 1 / n )The relative density of the PO4 monazite composite ceramic solid body reaches 95-98%.

5. A NZP-high entropy (Ln) according to any one of claims 1 to 4 1 / n ) A method for preparing a PO4 monazite type composite ceramic solid body, characterized in that: include: Strontium nitrate, ammonium dihydrogen phosphate, zirconium oxide and at least five of the seven oxides of lanthanum oxide, neodymium oxide, samarium oxide, europium oxide, gadolinium oxide, holmium oxide and erbium oxide are used as raw materials, the raw materials are mixed evenly and then pretreated to obtain pretreated powder, a sintering aid is added to the pretreated powder and mixed again, a binder is added to the obtained powder for granulation and aging, and then molding and plastic removal are performed, and finally NZP-high entropy (LnO2) is prepared in situ by sintering. 1 / n )PO4 monazite type composite ceramic solid body.

6. NZP-high entropy (Ln) as claimed in claim 5 1 / n ) A method for preparing a PO4 monazite type composite ceramic solid body, characterized in that: The raw materials are mixed by mechanical mixing, using any one of a ball mill and a jet mill, and the mixing time is 12 to 24 hours.

7. NZP-high entropy (Ln) as claimed in claim 5 1 / n ) A method for preparing a PO4 monazite type composite ceramic solid body, characterized in that: The pretreatment process is: calcining pretreatment at 600-700° C. in a muffle furnace for 4-8 hours.

8. NZP-high entropy (Ln) as claimed in claim 5 1 / n ) A method for preparing a PO4 monazite type composite ceramic solid body, characterized in that: The sintering aid is ZnO, and the added amount is 0.5-1.5wt.% of the mass of the pretreated powder; the binder is a polyvinyl alcohol solution, and the concentration of the polyvinyl alcohol solution is 6-8wt.%, and the amount of polyvinyl alcohol is 5-7wt.% of the mass of the raw material powder.

9. NZP-high entropy (Ln) as claimed in claim 5 1 / n ) A method for preparing a PO4 monazite type composite ceramic solid body, characterized in that: The molding is isostatic pressing or dry pressing, the pressure is 200-250 MPa, and the holding time is 3-5 minutes. The plastic discharge process is: the plastic discharge temperature is 600-700°C, and the holding time is 0.5-1.5 hours.

10. NZP-high entropy (Ln) as claimed in claim 5 1 / n ) A method for preparing a PO4 monazite type composite ceramic solid body, characterized in that: The sintering is any one of conventional solid phase sintering and microwave sintering, the sintering temperature is 1050-1250° C., and the holding time is 1.5-2.5 hours.

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