Magnesium oxide-medium / high-entropy zirconate pyrochlore composite ceramic inert fuel base material and one-step preparation method

Abstract

The invention discloses a magnesium oxide-medium / high-entropy zirconate pyrochlore multiphase ceramic inert fuel base material and a one-step preparation method, the magnesium oxide-medium / high-entropy zirconate pyrochlore multiphase ceramic inert fuel base material has a chemical general formula of omega MgO-(1-omega) (A1 / n) 2Zr2O7, omega represents 30-80wt.%, (1-omega) (A1 / n) 2Zr2O7, (1-omega) (A1 / n) 2Zr2O7, (1-omega) (A1 / n) 2Zr2O7, (1-omega) (A1 / n) 2Zr2O7, (1-omega) (A1 / n) 2Zr2O7, (1-omega) (1 N represents the number of element types of A lattice sites in (A1 / n) 2Zr2O7 pyrochlore, and n is an integer and is greater than or equal to 3 and less than or equal to 5; meanwhile, the types of the elements are selected from La, Nd, Sm, Y and Er, and the types of the elements and the mass ratio of the two crystal phases in the composite ceramic can be regulated and controlled at will. The composition design and one-step preparation method of the MgO-medium / high-entropy (A1 / n) 2Zr2O7 composite ceramic inert fuel base material, provided by the invention, have the advantages of flexible composition design, simple preparation process flow, high product compactness, suitability for simultaneous transmutation treatment of Pu and various MA and the like.

Description

Technical Field

[0001] The invention belongs to the field of inert fuel substrates in nuclear reactors, and relates to a magnesium oxide-medium / high entropy zirconate pyrochlore composite ceramic inert fuel substrate and a one-step preparation method, which is suitable for simultaneous transmutation treatment of Pu and multiple MAs. Background Art

[0002] With the continuous increase in the number of commercial nuclear power plants around the world and the decommissioning of nuclear weapons, the global reserves of radioactive plutonium (Pu) and minor actinides (MA) have increased dramatically. It is difficult to fundamentally solve their radioactive hazards and potential threats by relying on traditional deep geological disposal methods. In order to reduce and make full use of the accumulated Pu, they can be made into MOX fuel (mixed oxidized fuel of PuO2 and UO2) and re-burned in light water reactors. However, due to the presence of Pu in MOX fuel, the amount of Pu in MOX fuel is very high. 238 U will form new Pu and MA after capturing neutrons, and Pu and MA cannot be eliminated from the source. Since the 1990s, the international community has been committed to using inert matrix fuel (IMF) to replace MOX in light water reactors, fast neutron reactors and accelerator-driven subcritical systems (ADS) to solve the problem of large Pu and MA stocks and difficulty in being digested by the environment in a short period of time. 238 U's IMF is made by dispersing PuO2 in an inert matrix (IM), which can eliminate the generation of Pu and MA from the source. In order to ensure the safe operation of the reactor, the selection conditions of IM are extremely stringent: such as 1) a small neutron absorption cross section; 2) good irradiation stability; 3) excellent physical and chemical properties, etc.

[0003] "MgO-Nd2Zr2O7" composite ceramics are considered to be one of the most promising IM candidate materials. The MgO phase and Nd2Zr2O7 pyrochlore phase are not only highly complementary in performance and can meet the performance requirements of the reactor; they can also make full use of the Nd and Zr lattice sites of the Nd2Zr2O7 pyrochlore phase to dissolve MA and Pu, thereby improving the burnup of Pu and MA. Therefore, based on the "MgO-Nd2Zr2O7" composite ceramics, the chemical composition of Nd2Zr2O7 pyrochlore in the composite ceramics can be designed to be medium / high entropy (A 1 / n )2Zr2O7 pyrochlore, preparation of "MgO-medium / high entropy (A)" capable of simultaneously transmuting Pu and various MA 1 / n )2Zr2O7" composite ceramic inert fuel substrate to achieve efficient transmutation treatment of Pu and various MAs.

[0004] The object of the present invention is to provide a kind of MgO containing only and medium / high entropy (A 1 / n)2Zr2O7 pyrochlore, two crystalline phases, can be used in the inert matrix fuel of the reactor, and can simultaneously transmute a variety of MA dense "MgO-medium / high entropy (A 1 / n )2Zr2O7" composite ceramic inert fuel matrix composition design and one-step preparation method. The existing "MgO-Nd2Zr2O7" composite ceramics have broken through the traditional two-step method (first synthesis and then composite sintering) in the preparation process, that is, the synthesis of Nd2Zr2O7 pyrochlore and its composite sintering with MgO to prepare "MgO-Nd2Zr2O7" composite ceramics by a one-step solid phase reaction method. However, for the simultaneous transmutation treatment of Pu and MA, the Nd in the "MgO-Nd2Zr2O7" composite ceramics only represents one MA simulation nuclide (usually the +3 valent Nd in the non-radioactive lanthanide elements is used to simulate the radioactive +3 valent Am in the actinide). Therefore, in order to be able to process multiple MAs at the same time, medium / high entropy ceramics (comparatively with high entropy effects and better stability) have gradually begun to enter the research field of nuclear materials in recent years, including medium / high entropy (A 1 / n )2Zr2O7 zirconate pyrochlore for simultaneous solidification treatment of multiple simulated MA. In view of this, the present invention aims at the deficiency that the existing "MgO-Nd2Zr2O7" composite ceramics can transmute a single type of MA, and in the "MgO-Nd2Zr2O7" composite ceramics and medium / high entropy (A 1 / n )2Zr2O7 pyrochlore, a "MgO-medium / high entropy (A)" process for simultaneous transmutation of Pu and various MAs is provided. 1 / n )2Zr2O7" composite ceramic composition design and one-step preparation method, and the prepared "MgO-medium / high entropy (A 1 / n )2Zr2O7" composite ceramics have high density, among which (A 1 / n The composition of )2Zr2O7 pyrochlore and the mass percentage of the two crystalline phases can be arbitrarily adjusted according to actual conditions. The present invention is a "MgO-medium / high entropy (A)" that can simultaneously transmute Pu and various MA in a nuclear reactor. 1 / n )2Zr2O7" composite ceramic inert fuel matrix provides composition design and a simple and effective one-step preparation method. Summary of the invention

[0005] The purpose of the present invention is to overcome the deficiency of the existing "MgO-Nd2Zr2O7" composite ceramics that can transmute a single type of MA, and to provide a "MgO-medium / high entropy (A)" composite ceramic that can transmute Pu and multiple MA simultaneously in a nuclear reactor. 1 / n )2Zr2O7" composite ceramic inert fuel substrate composition design and one-step preparation method.

[0006] 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.

[0007] In order to achieve these purposes and other advantages according to the present invention, a magnesium oxide-medium / high entropy zirconate pyrochlore composite ceramic inert fuel substrate is provided, characterized in that the magnesium oxide-medium / high entropy zirconate pyrochlore composite ceramic inert fuel substrate has a chemical formula of: ωMgO-(1-ω)(A 1 / n )2Zr2O7, where ω represents the mass percentage, ranging from 30 to 80wt.%; n represents (A 1 / n )The number of element types at the A lattice site in the 2Zr2O7 pyrochlore, n is an integer and 3≤n≤5; at the same time, the element types are selected from La, Nd, Sm, Y, and Er, and the element types and the mass ratio of the two crystalline phases in the composite ceramic can be arbitrarily controlled.

[0008] Preferably, when n is 3, (A 1 / n )2Zr2O7 is medium entropy pyrochlore, A=La 1 / 3 Nd 1 / 3 Sm 1 / 3 The general chemical formula of the magnesium oxide-medium / high entropy zirconate pyrochlore composite ceramic inert fuel substrate is: ωMgO-(1-ω)(La 1 / 3 Nd 1 / 3Sm 1 / 3 )2Zr2O7;

[0009] When n is 4, (A 1 / n )2Zr2O7 is medium entropy pyrochlore, A=La 1 / 4 Nd 1 / 4 Sm 1 / 4 Y 1 / 4 The general chemical formula of the magnesium oxide-medium / high entropy zirconate pyrochlore composite ceramic inert fuel substrate is: ωMgO-(1-ω)(La 1 / 4 Nd 1 / 4 Sm 1 / 4 Y 1 / 4 )2Zr2O7;

[0010] When n is 5, (A 1 / n )2Zr2O7 is a high entropy pyrochlore, A=La 1 / 5 Nd 1 / 5 Sm 1 / 5 Y 1 / 5 Er 1 / 5 The general chemical formula of the magnesium oxide-medium / high entropy zirconate pyrochlore composite ceramic inert fuel substrate is: ωMgO-(1-ω)(La 1 / 5 Nd 1 / 5 Sm 1 / 5 Y 1 / 5E 1 / 5 )2Zr2O7.

[0011] Preferably, the crystal phase composition of the magnesium oxide-medium / high entropy zirconate pyrochlore composite ceramic inert fuel substrate is a composite phase of two crystal phases, namely magnesium oxide and medium / high entropy zirconate pyrochlore.

[0012] Preferably, when n is 3, the crystal phase composition of the magnesium oxide-medium / high entropy zirconate pyrochlore composite ceramic inert fuel substrate is magnesium oxide and three components of medium entropy (La 1 / 3 Nd 1 / 3 Sm 1 / 3 )2Zr2O7 composite phase of two crystalline phases of pyrochlore;

[0013] When n is 4, the crystal phase composition of the magnesium oxide-medium / high entropy zirconate pyrochlore composite ceramic inert fuel substrate is magnesium oxide and four-component medium entropy (La 1 / 4 Nd 1 / 4 Sm 1 / 4 Y 1 / 4 )2Zr2O7 composite phase of two crystalline phases of pyrochlore;

[0014] When n is 5, the crystal phase composition of the magnesium oxide-medium / high entropy zirconate pyrochlore composite ceramic inert fuel substrate is magnesium oxide and five-component high entropy (La 1 / 5 Nd 1 / 5 Sm 1 / 5 Y 1 / 5 Er 1 / 5 )2Zr2O7 is a composite phase of two crystalline phases of pyrochlore.

[0015] Preferably, the relative density of the magnesium oxide-medium / high entropy zirconate pyrochlore composite ceramic inert fuel substrate reaches 93-99%.

[0016] The present invention also provides a method for preparing the magnesium oxide-medium / high entropy zirconate pyrochlore composite ceramic inert fuel substrate as described above, comprising: mixing raw materials of magnesium oxide, zirconium oxide and a plurality of oxides, adding a binder, aging, molding and plastic removal, and then directly adopting a solid phase reaction one-step sintering method to prepare the magnesium oxide-medium / high entropy zirconate pyrochlore composite ceramic inert fuel substrate; wherein the plurality of oxides are at least three of the following five oxides, and the five oxides are: lanthanum oxide, neodymium oxide, samarium oxide, erbium oxide, and yttrium oxide.

[0017] Preferably, the mixing method is ball milling mixing, the ball milling mixing uses a planetary ball mill for wet ball milling, the ball milling time is 5 to 10 hours, the ball milling medium is zirconia balls, and the ball milling dispersant is alcohol, wherein the raw material: zirconia balls: alcohol = 1:1 to 2:1 to 3.

[0018] Preferably, the binder is a PVA solution with a concentration of 4 to 10 wt.%, and its usage is 5 to 7 wt.% of the total mass of the mixed raw materials.

[0019] Preferably, the molding is cold isostatic pressing, the molding pressure is 160-240 MPa, and the molding time is 2-5 min; the plastic discharge temperature is 550-850° C., and the insulation time is 0.5-2 h.

[0020] Preferably, the solid phase reaction one-step sintering is muffle furnace high temperature sintering, the heating rate is 3-6°C / min; the sintering temperature is 1400-1500°C, and the sintering time is 3-12h.

[0021] Preferably, the zirconium oxide is treated before use: ZrO2, H2O and H2O2 with a mass ratio of 1:2-4:3-6 are placed in a high-temperature and high-pressure reactor, i.e., a supercritical reactor, and stirred (speed 300-500r / min) for 5-20 minutes under a supercritical state (temperature 300-400°C, pressure 25-35Mpa), and filtered and vacuum dried to obtain pretreated zirconium oxide;

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

[0023] (1) The "MgO-medium / high entropy (A)" prepared by the present invention 1 / n )2Zr2O7" composite ceramic inert fuel matrix combines magnesium oxide and medium / high entropy (A 1 / n )2Zr2O7 pyrochlore has the following characteristics: on the one hand, MgO has high thermal conductivity and is easily soluble in acid, which is conducive to post-processing; on the other hand, medium / high entropy (A 1 / n )2Zr2O7 pyrochlore has excellent radiation resistance and chemical stability, which can effectively improve the poor water corrosion resistance of MgO under high temperature conditions. 1 / n )2Zr2O7 pyrochlore's A lattice site can simultaneously dissolve a variety of trivalent MAs and can be used in the reactor "MgO-medium / high entropy (A 1 / n Simultaneous transmutation of Pu and various MA in a composite ceramic inert matrix fuel.

[0024] (2) Based on the preparation process of "MgO-Nd2Zr2O7" composite ceramics, the present invention introduces a variety of rare earth oxides and transition metal oxides Y2O3, and adopts a one-step solid phase reaction method to prepare "MgO-medium / high entropy (A 1 / n )2Zr2O7" composite ceramic inert fuel matrix, achieving medium / high entropy (A 1 / nThe synthesis of )2Zr2O7 pyrochlore and its composite sintering integration with MgO provide a one-step preparation method that can simultaneously transmutate multiple MAs, is simple and energy-efficient. During the high-temperature sintering process, the rare earth oxide raw materials La2O3, Nd2O3, Sm2O3, Er2O3 and the transition metal oxide Y2O3 react with ZrO2 to generate three components of entropy (La 1 / 3 Nd 1 / 3 Sm 1 / 3 )2Zr2O7 pyrochlore, four-component intermediate entropy (La 1 / 4 Nd 1 / 4 Sm 1 / 4 Y 1 / 4 )2Zr2O7 pyrochlore and five-component high entropy (La 1 / 5 Nd 1 / 5 Sm 1 / 5 Y 1 / 5 Er 1 / 5 )2Zr2O7 pyrochlore, while MgO does not participate in the reaction to form new phases, and directly reacts with the generated medium / high entropy (A 1 / n )2Zr2O7 pyrochlore together form a dense "MgO-medium / high entropy (A 1 / n )2Zr2O7" composite ceramics, and the prepared composite ceramics have the advantages of high density and simple process;

[0025] (4) The present invention adopts a solid phase reaction one-step method to prepare "MgO-medium / high entropy (A) 1 / n )2Zr2O7" composite ceramic inert fuel substrate, the raw materials used are all oxides, the raw materials are easy to obtain, the preparation process is simple, which is conducive to engineering application and promotion;

[0026] (5) The present invention adopts a solid phase reaction one-step method to prepare "MgO-medium / high entropy (A) 1 / n )2Zr2O7" composite ceramic inert fuel matrix, which can adjust the medium / high entropy (A) according to the specific situation 1 / n )2Zr2O7 pyrochlore element types and the mass percentages of the two crystalline phases, which are practical for the simultaneous transmutation treatment of Pu and multiple MA elements;

[0027] In summary, the "MgO-medium / high entropy (A 1 / n The composition design and one-step preparation method of the ")2Zr2O7" composite ceramic inert fuel substrate have the advantages of flexible composition design, simple preparation process, high product density, and suitability for simultaneous transmutation treatment of Pu and multiple MAs.

[0028] 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

[0029] Figure 1 The "50wt.% MgO-50wt.% medium / high entropy (A)" prepared in Examples 1, 2 and 3 of the present invention 1 / n )2Zr2O7(n=3 / 4 / 5)” composite ceramic XRD pattern;

[0030] Figure 2 "50wt.%MgO-50wt.%Medium / High Entropy (A)" prepared in Examples 1, 2 and 3 1 / n )2Zr2O7(n=3 / 4 / 5)” cross-sectional scanning electron microscope image of the composite ceramic;

[0031] Figure 3 Part of the "ωMgO-(1-ω) high entropy (La 1 / 5 Nd 1 / 5 Sm 1 / 5 Y 1 / 5 Er 1 / 5 )2Zr2O7 (ω=30~70wt.%)” composite ceramics thermal expansion test process relative elongation variation curve with temperature;

[0032] Figure 4 Part of the "ωMgO-(1-ω) high entropy (La 1 / 5 Nd 1 / 5 Sm 1 / 5 Y 1 / 5 Er 1 / 5 )2Zr2O7 (ω=30~70wt.%)” thermal conductivity of composite ceramics changes with temperature;

[0033] Figure 5 The 500KeV He 2+ "50wt.%MgO-50wt.%High Entropy (La 1 / 5 Nd 1 / 5Sm 1 / 5 Y 1 / 5 Er 1 / 5 )GIXRD spectrum of the 2Zr2O7" composite ceramic (prepared in Example 3) at a grazing incidence angle γ = 1.0° (where the radiation damage is the largest);

[0034] Figure 6 Preparation of "50wt.% MgO-50wt.% medium / high entropy (A)" for Examples 1, 2, and 3 1 / n )2Zr2O7(n=3 / 4 / 5)” composite ceramics composite ceramics under the same irradiation conditions (500KeV He 2+ , 1×10 17 ions / cm 2)’s GIXRD spectrum. DETAILED DESCRIPTION

[0035] 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.

[0036] It should be understood that terms such as “having”, “including” and “comprising” used herein do not specify the existence or addition of one or more other elements or combinations thereof.

[0037] Embodiment 1:

[0038] In this example, the one-step preparation of "MgO-medium entropy (A 1 / n The chemical composition of the composite ceramic inert fuel matrix is ​​designed to be 50wt.%MgO-50wt.%(La 1 / 3 Nd 1 / 3 Sm 1 / 3 )2Zr2O7, the preparation process of which comprises the following steps:

[0039] (1) Ingredients: MgO, La2O3, Nd2O3, Sm2O3, and ZrO2 are used as raw materials and are prepared according to a stoichiometric ratio; wherein the following chemical reaction occurs between La2O3, Nd2O3, Sm2O3, and ZrO2: La2O3+Nd2O3+Sm2O3+6ZrO2=3(La 1 / 3 Nd 1 / 3 Sm 1 / 3 )2Zr2O7, MgO did not participate in the chemical reaction; according to their respective molecular weights and contents, the molar ratio of each raw material is: MgO: La2O3: Nd2O3: Sm2O3: ZrO2 = 43.43: 1: 1: 1: 6;

[0040] (2) Mixing: The raw materials were wet-milled for 10 h using a planetary ball mill and then dried in an oven at 60° C. Zirconia balls were used as the ball milling medium to avoid the introduction of impurities. The mass ratio of the raw materials, zirconia balls, and alcohol was as follows: raw materials: balls: alcohol = 1:1.5:2;

[0041] (3) Aging: Add 6 wt.% of PVA solution (concentration 6 wt.%) to the dried mixed raw material powder, disperse it evenly in a mortar, and then put it into a sealed bag and age it in a cool place for 1 day;

[0042] (4) Molding: The aged material is initially pressed into a disc blank with a thickness of 2-3 mm using a φ12 mm mold. The initial pressing pressure is 2 MPa and the pressure is maintained for 30 seconds. Subsequently, further isostatic pressing is performed at a pressure of 200 MPa for 3 minutes. The formed blank is then discharged in a resistance furnace at 700°C for 1 hour.

[0043] (5) Sintering: The molded green body was placed in a muffle furnace and heated to 1500°C at a rate of 5°C / min for 6 h to obtain "50wt.%MgO-50wt.% medium entropy (La 1 / 3 Nd 1 / 3 Sm 1 / 3 )2Zr2O7" composite ceramics (50wt.% M-50wt.% LNSZO).

[0044] Embodiment 2:

[0045] In this example, the one-step preparation of "MgO-medium entropy (A 1 / n The chemical composition of the composite ceramic inert fuel matrix is ​​designed to be 50wt.%MgO-50wt.%(La 1 / 4 Nd 1 / 4 Sm 1 / 4 Y 1 / 4 )2Zr2O7, the preparation process of which comprises the following steps:

[0046] (1) Ingredients: MgO, La2O3, Nd2O3, Sm2O3, Y2O3, and ZrO2 are used as raw materials and are prepared according to a stoichiometric ratio; wherein the following chemical reaction occurs between La2O3, Nd2O3, Sm2O3, Y2O3, and ZrO2: La2O3+Nd2O3+Sm2O3+Y2O3+8ZrO2=4(La 1 / 4 Nd 1 / 4 Sm 1 / 4 Y 1 / 4 )2Zr2O7, MgO did not participate in the chemical reaction; according to their respective molecular weights and contents, the molar ratio of each raw material is: MgO: La2O3: Nd2O3: Sm2O3: Y2O3: ZrO2 = 55.15: 1: 1: 1: 8;

[0047] (2) Mixing: The raw materials were wet-milled for 10 h using a planetary ball mill and then dried in an oven at 60° C. Zirconia balls were used as the ball milling medium to avoid the introduction of impurities. The mass ratio of the raw materials, zirconia balls, and alcohol was as follows: raw materials: balls: alcohol = 1:1.5:2;

[0048] (3) Aging: Add 6 wt.% of PVA solution (concentration 6 wt.%) to the dried mixed raw material powder, disperse it evenly in a mortar, and then put it into a sealed bag and age it in a cool place for 1 day;

[0049] (4) Molding: The aged material is initially pressed into a disc blank with a thickness of 2-3 mm using a φ12 mm mold. The initial pressing pressure is 2 MPa and the pressure is maintained for 30 seconds. Subsequently, further isostatic pressing is performed at a pressure of 200 MPa for 3 minutes. The formed blank is then discharged in a resistance furnace at 700°C for 1 hour.

[0050] (5) Sintering: The molded green body was placed in a muffle furnace and heated to 1500°C at a rate of 5°C / min for 6 h to obtain "50wt.%MgO-50wt.% medium entropy (La 1 / 4 Nd 1 / 4 Sm 1 / 4 Y 1 / 4 )2Zr2O7" composite ceramics (50wt.% M-50wt.% LNSYZO).

[0051] Embodiment 3:

[0052] In this example, the one-step preparation of "MgO-high entropy (A 1 / n The chemical composition of the composite ceramic inert fuel matrix is ​​designed to be 50wt.%MgO-50wt.%(La 1 / 5 Nd 1 / 5 Sm 1 / 5 Y 1 / 5 Er 1 / 5 )2Zr2O7, the preparation process of which comprises the following steps:

[0053] (1) Ingredients: MgO, La2O3, Nd2O3, Sm2O3, Y2O3, Er2O3, and ZrO2 are used as raw materials and are prepared according to the stoichiometric ratio; the following chemical reactions occur between La2O3, Nd2O3, Sm2O3, Y2O3, Er2O3, and ZrO2:

[0054] La2O3+Nd2O3+Sm2O3+Y2O3+Er2O3+10ZrO2=5(La 1 / 5 Nd 1 / 5 Sm 1 / 5 Y 1 / 5 Er 1 / 5 )2Zr2O7,

[0055] MgO does not participate in the chemical reaction; according to their respective molecular weights and contents, the molar ratio of the raw materials is: MgO: La2O3: Nd2O3: Sm2O3: Y2O3: Er2O3: ZrO2 = 70.76: 1: 1: 1: 1: 1: 10;

[0056] (2) Mixing: The raw materials were wet-milled for 10 h using a planetary ball mill and then dried in an oven at 60° C. Zirconia balls were used as the ball milling medium to avoid the introduction of impurities. The mass ratio of the raw materials, zirconia balls, and alcohol was as follows: raw materials: balls: alcohol = 1:1.5:2;

[0057] (3) Aging: Add 6 wt.% of PVA solution (concentration 6 wt.%) to the dried mixed raw material powder, disperse it evenly in a mortar, and then put it into a sealed bag and age it in a cool place for 1 day;

[0058] (4) Molding: The aged material is initially pressed into a disc blank with a thickness of 2-3 mm using a φ12 mm mold. The initial pressing pressure is 2 MPa and the pressure is maintained for 30 seconds. Subsequently, further isostatic pressing is performed at a pressure of 200 MPa for 3 minutes. The formed blank is then discharged in a resistance furnace at 700°C for 1 hour.

[0059] (5) Sintering: The molded green body was placed in a muffle furnace and heated to 1500°C at a rate of 5°C / min for 6 h to obtain "50wt.% MgO-50wt.% high entropy (La 1 / 5 Nd 1 / 5 Sm 1 / 5 Y 1 / 5 )2Zr2O7" composite ceramics (50wt.% M-50wt.% LNSYEZO).

[0060] Embodiment 4:

[0061] In this example, the one-step preparation of "MgO-high entropy (A 1 / n The chemical composition of the composite ceramic inert fuel matrix is ​​designed to be 20wt.% MgO-80wt.% (La 1 / 5 Nd 1 / 5 Sm 1 / 5 Y 1 / 5 Er 1 / 5 )2Zr2O7, the preparation process of which comprises the following steps:

[0062] (1) Ingredients: MgO, La2O3, Nd2O3, Sm2O3, Y2O3, Er2O3, and ZrO2 are used as raw materials and are prepared according to the stoichiometric ratio; the following chemical reactions occur between La2O3, Nd2O3, Sm2O3, Y2O3, Er2O3, and ZrO2:

[0063] La2O3+Nd2O3+Sm2O3+Y2O3+Er2O3+10ZrO2=5(La 1 / 5 Nd 1 / 5 Sm 1 / 5 Y 1 / 5Er 1 / 5 )2Zr2O7,

[0064] MgO does not participate in the chemical reaction; according to their respective molecular weights and contents, the molar ratio of the raw materials is: MgO: La2O3: Nd2O3: Sm2O3: Y2O3: Er2O3: ZrO2 = 17.7: 1: 1: 1: 1: 1: 10;

[0065] (2) Mixing: The raw materials were wet-milled for 10 h using a planetary ball mill and then dried in an oven at 60° C. Zirconia balls were used as the ball milling medium to avoid the introduction of impurities. The mass ratio of the raw materials, zirconia balls, and alcohol was as follows: raw materials: balls: alcohol = 1:1.5:2;

[0066] (3) Aging: Add 6 wt.% of PVA solution (concentration 6 wt.%) to the dried mixed raw material powder, disperse it evenly in a mortar, and then put it into a sealed bag and age it in a cool place for 1 day;

[0067] (4) Molding: The aged material is initially pressed into a disc blank with a thickness of 2-3 mm using a φ12 mm mold. The initial pressing pressure is 2 MPa and the pressure is maintained for 30 seconds. Subsequently, further isostatic pressing is performed at a pressure of 200 MPa for 3 minutes. The formed blank is then discharged in a resistance furnace at 700°C for 1 hour.

[0068] (5) Sintering: The molded green body was placed in a muffle furnace and heated to 1500°C at a rate of 5°C / min for 6 h to obtain "20wt.% MgO-80wt.% high entropy (La 1 / 5 Nd 1 / 5 Sm 1 / 5 Y 1 / 5 Er 1 / 5 )2Zr2O7" composite ceramics (20wt.% M-80wt.% LNSYEZO).

[0069] Embodiment 5:

[0070] In this example, the one-step preparation of "MgO-high entropy (A 1 / n The chemical composition of the composite ceramic inert fuel matrix is ​​designed to be 30wt.%MgO-70wt.%(La 1 / 5 Nd 1 / 5 Sm 1 / 5 Y 1 / 5 Er 1 / 5 )2Zr2O7, the preparation process of which comprises the following steps:

[0071] (1) Ingredients: MgO, La2O3, Nd2O3, Sm2O3, Y2O3, Er2O3, and ZrO2 are used as raw materials and are prepared according to the stoichiometric ratio; the following chemical reactions occur between La2O3, Nd2O3, Sm2O3, Y2O3, Er2O3, and ZrO2:

[0072] La2O3+Nd2O3+Sm2O3+Y2O3+Er2O3+10ZrO2=5(La 1 / 5 Nd 1 / 5 Sm 1 / 5 Y 1 / 5 Er 1 / 5 )2Zr2O7,

[0073] MgO does not participate in the chemical reaction; according to their respective molecular weights and contents, the molar ratio of the raw materials is: MgO: La2O3: Nd2O3: Sm2O3: Y2O3: Er2O3: ZrO2 = 30.33: 1: 1: 1: 1: 1: 10;

[0074] (2) Mixing: The raw materials were wet-milled for 10 h using a planetary ball mill and then dried in an oven at 60° C. Zirconia balls were used as the ball milling medium to avoid the introduction of impurities. The mass ratio of the raw materials, zirconia balls, and alcohol was as follows: raw materials: balls: alcohol = 1:1.5:2;

[0075] (3) Aging: Add 6 wt.% of PVA solution (concentration 6 wt.%) to the dried mixed raw material powder, disperse it evenly in a mortar, and then put it into a sealed bag and age it in a cool place for 1 day;

[0076] (4) Molding: The aged material is initially pressed into a disc blank with a thickness of 2-3 mm using a φ12 mm mold. The initial pressing pressure is 2 MPa and the pressure is maintained for 30 seconds. Subsequently, further isostatic pressing is performed at a pressure of 200 MPa for 3 minutes. The formed blank is then discharged in a resistance furnace at 700°C for 1 hour.

[0077] (5) Sintering: The molded green body was placed in a muffle furnace and heated to 1500°C at a rate of 5°C / min for 6 h to obtain "30wt.%MgO-70wt.%High Entropy (La 1 / 5 Nd 1 / 5 Sm 1 / 5 Y 1 / 5 Er 1 / 5 )2Zr2O7" composite ceramics (30wt.% M-70wt.% LNSYEZO).

[0078] Embodiment 6:

[0079] In this example, the one-step preparation of "MgO-high entropy (A 1 / n The chemical composition of the composite ceramic inert fuel matrix is ​​designed to be 40wt.%MgO-60wt.%(La 1 / 5 Nd 1 / 5 Sm 1 / 5 Y 1 / 5 Er 1 / 5 )2Zr2O7, the preparation process of which comprises the following steps:

[0080] (1) Ingredients: MgO, La2O3, Nd2O3, Sm2O3, Y2O3, Er2O3, and ZrO2 are used as raw materials and are prepared according to the stoichiometric ratio; the following chemical reactions occur between La2O3, Nd2O3, Sm2O3, Y2O3, Er2O3, and ZrO2:

[0081] La2O3+Nd2O3+Sm2O3+Y2O3+Er2O3+10ZrO2=5(La 1 / 5 Nd 1 / 5 Sm 1 / 5 Y 1 / 5 Er 1 / 5 )2Zr2O7,

[0082] MgO does not participate in the chemical reaction; according to their respective molecular weights and contents, the molar ratio of the raw materials is: MgO: La2O3: Nd2O3: Sm2O3: Y2O3: Er2O3: ZrO2 = 47.17: 1: 1: 1: 1: 1: 10;

[0083] (2) Mixing: The raw materials were wet-milled for 10 h using a planetary ball mill and then dried in an oven at 60° C. Zirconia balls were used as the ball milling medium to avoid the introduction of impurities. The mass ratio of the raw materials, zirconia balls, and alcohol was as follows: raw materials: balls: alcohol = 1:1.5:2;

[0084] (3) Aging: Add 6 wt.% of PVA solution (concentration 6 wt.%) to the dried mixed raw material powder, disperse it evenly in a mortar, and then put it into a sealed bag and age it in a cool place for 1 day;

[0085] (4) Molding: The aged material is initially pressed into a disc blank with a thickness of 2-3 mm using a φ12 mm mold. The initial pressing pressure is 2 MPa and the pressure is maintained for 30 seconds. Subsequently, further isostatic pressing is performed at a pressure of 200 MPa for 3 minutes. The formed blank is then discharged in a resistance furnace at 700°C for 1 hour.

[0086] (5) Sintering: The molded green body was placed in a muffle furnace and heated to 1500°C at a rate of 5°C / min for 6 h to obtain "40wt.% MgO-60wt.% high entropy (La 1 / 5 Nd 1 / 5 Sm 1 / 5 Y 1 / 5 Er 1 / 5 )2Zr2O7" composite ceramics (40wt.%M-60wt.%LNSYEZO).

[0087] Embodiment 7:

[0088] In this example, the one-step preparation of "MgO-high entropy (A 1 / n The chemical composition of the composite ceramic inert fuel matrix is ​​designed to be 60wt.%MgO-40wt.%(La 1 / 5 Nd 1 / 5 Sm 1 / 5 Y 1 / 5 Er 1 / 5 )2Zr2O7, the preparation process of which comprises the following steps:

[0089] (1) Ingredients: MgO, La2O3, Nd2O3, Sm2O3, Y2O3, Er2O3, and ZrO2 are used as raw materials and are prepared according to the stoichiometric ratio; the following chemical reactions occur between La2O3, Nd2O3, Sm2O3, Y2O3, Er2O3, and ZrO2:

[0090] La2O3+Nd2O3+Sm2O3+Y2O3+Er2O3+10ZrO2=5(La 1 / 5 Nd 1 / 5 Sm 1 / 5 Y 1 / 5 Er 1 / 5 )2Zr2O7,

[0091] MgO does not participate in the chemical reaction; according to their respective molecular weights and contents, the molar ratio of the raw materials is: MgO: La2O3: Nd2O3: Sm2O3: Y2O3: Er2O3: ZrO2 = 106.14: 1: 1: 1: 1: 1: 10;

[0092] (2) Mixing: The raw materials were wet-milled for 10 h using a planetary ball mill and then dried in an oven at 60° C. Zirconia balls were used as the ball milling medium to avoid the introduction of impurities. The mass ratio of the raw materials, zirconia balls, and alcohol was as follows: raw materials: balls: alcohol = 1:1.5:2;

[0093] (3) Aging: Add 6 wt.% of PVA solution (concentration 6 wt.%) to the dried mixed raw material powder, disperse it evenly in a mortar, and then put it into a sealed bag and age it in a cool place for 1 day;

[0094] (4) Molding: The aged material is initially pressed into a disc blank with a thickness of 2-3 mm using a φ12 mm mold. The initial pressing pressure is 2 MPa and the pressure is maintained for 30 seconds. Subsequently, further isostatic pressing is performed at a pressure of 200 MPa for 3 minutes. The formed blank is then discharged in a resistance furnace at 700°C for 1 hour.

[0095] (5) Sintering: The molded green body was placed in a muffle furnace and heated to 1500°C at a rate of 5°C / min for 6 h to obtain "60wt.%MgO-40wt.%High Entropy (La 1 / 5 Nd 1 / 5 Sm 1 / 5 Y 1 / 5 Er 1 / 5 )2Zr2O7" composite ceramics (60wt.%M-40wt.%LNSYEZO).

[0096] Embodiment 8:

[0097] In this example, the one-step preparation of "MgO-high entropy (A 1 / n The chemical composition of the composite ceramic inert fuel matrix is ​​designed to be 70wt.%MgO-30wt.%(La 1 / 5 Nd 1 / 5 Sm 1 / 5 Y 1 / 5 Er 1 / 5 )2Zr2O7, the preparation process of which comprises the following steps:

[0098] (1) Ingredients: MgO, La2O3, Nd2O3, Sm2O3, Y2O3, Er2O3, and ZrO2 are used as raw materials and are prepared according to the stoichiometric ratio; the following chemical reactions occur between La2O3, Nd2O3, Sm2O3, Y2O3, Er2O3, and ZrO2:

[0099] La2O3+Nd2O3+Sm2O3+Y2O3+Er2O3+10ZrO2=5(La 1 / 5 Nd 1 / 5 Sm 1 / 5 Y 1 / 5 Er 1 / 5 )2Zr2O7,

[0100] MgO does not participate in the chemical reaction; according to their respective molecular weights and contents, the molar ratio of the raw materials is: MgO: La2O3: Nd2O3: Sm2O3: Y2O3: Er2O3: ZrO2 = 165.1: 1: 1: 1: 1: 1: 10;

[0101] (2) Mixing: The raw materials were wet-milled for 10 h using a planetary ball mill and then dried in an oven at 60° C. Zirconia balls were used as the ball milling medium to avoid the introduction of impurities. The mass ratio of the raw materials, zirconia balls, and alcohol was as follows: raw materials: balls: alcohol = 1:1.5:2;

[0102] (3) Aging: Add 6 wt.% of PVA solution (concentration 6 wt.%) to the dried mixed raw material powder, disperse it evenly in a mortar, and then put it into a sealed bag and age it in a cool place for 1 day;

[0103] (4) Molding: The aged material is initially pressed into a disc blank with a thickness of 2-3 mm using a φ12 mm mold. The initial pressing pressure is 2 MPa and the pressure is maintained for 30 seconds. Subsequently, further isostatic pressing is performed at a pressure of 200 MPa for 3 minutes. The formed blank is then discharged in a resistance furnace at 700°C for 1 hour.

[0104] (5) Sintering: The molded green body was placed in a muffle furnace and heated to 1500°C at a rate of 5°C / min for 6 h to obtain "70wt.% MgO-30wt.% high entropy (La 1 / 5 Nd 1 / 5 Sm 1 / 5 Y 1 / 5 Er 1 / 5 )2Zr2O7" composite ceramics (70wt.% M-30wt.% LNSYEZO).

[0105] Embodiment 9:

[0106] In this example, the one-step preparation of "MgO-high entropy (A 1 / n The chemical composition of the composite ceramic inert fuel matrix is ​​designed to be 80wt.%MgO-20wt.%(La 1 / 5 Nd 1 / 5 Sm 1 / 5 Y 1 / 5 Er 1 / 5 )2Zr2O7, the preparation process of which comprises the following steps:

[0107] (1) Ingredients: MgO, La2O3, Nd2O3, Sm2O3, Y2O3, Er2O3, and ZrO2 are used as raw materials and are prepared according to the stoichiometric ratio; the following chemical reactions occur between La2O3, Nd2O3, Sm2O3, Y2O3, Er2O3, and ZrO2:

[0108] La2O3+Nd2O3+Sm2O3+Y2O3+Er2O3+10ZrO2=5(La 1 / 5 Nd 1 / 5 Sm 1 / 5 Y 1 / 5 Er 1 / 5 )2Zr2O7,

[0109] MgO does not participate in the chemical reaction; according to their respective molecular weights and contents, the molar ratio of the raw materials is: MgO: La2O3: Nd2O3: Sm2O3: Y2O3: Er2O3: ZrO2 = 283.03: 1: 1: 1: 1: 1: 10;

[0110] (2) Mixing: The raw materials were wet-milled for 10 h using a planetary ball mill and then dried in an oven at 60° C. Zirconia balls were used as the ball milling medium to avoid the introduction of impurities. The mass ratio of the raw materials, zirconia balls, and alcohol was as follows: raw materials: balls: alcohol = 1:1.5:2;

[0111] (3) Aging: Add 6 wt.% of PVA solution (concentration 6 wt.%) to the dried mixed raw material powder, disperse it evenly in a mortar, and then put it into a sealed bag and age it in a cool place for 1 day;

[0112] (4) Molding: The aged material is initially pressed into a disc blank with a thickness of 2-3 mm using a φ12 mm mold. The initial pressing pressure is 2 MPa and the pressure is maintained for 30 seconds. Subsequently, further isostatic pressing is performed at a pressure of 200 MPa for 3 minutes. The formed blank is then discharged in a resistance furnace at 700°C for 1 hour.

[0113] (5) Sintering: The molded green body was placed in a muffle furnace and heated to 1500°C at a rate of 5°C / min for 6 h to obtain "80wt.%MgO-20wt.% high entropy (La 1 / 5 Nd 1 / 5 Sm 1 / 5 Y 1 / 5 Er 1 / 5 )2Zr2O7" composite ceramics (70wt.% M-30wt.% LNSYEZO).

[0114] Embodiment 10:

[0115] In this example, the one-step preparation of "MgO-high entropy (A 1 / n The chemical composition of the composite ceramic inert fuel matrix is ​​designed to be 50wt.%MgO-50wt.%(La 1 / 5 Nd 1 / 5 Sm 1 / 5 Y 1 / 5 Er 1 / 5 )2Zr2O7, the preparation process of which comprises the following steps:

[0116] (1) Ingredients: MgO, La2O3, Nd2O3, Sm2O3, Y2O3, Er2O3, and ZrO2 are used as raw materials and are prepared according to the stoichiometric ratio; the following chemical reactions occur between La2O3, Nd2O3, Sm2O3, Y2O3, Er2O3, and ZrO2:

[0117] La2O3+Nd2O3+Sm2O3+Y2O3+Er2O3+10ZrO2=5(La 1 / 5 Nd 1 / 5 Sm 1 / 5 Y 1 / 5 Er 1 / 5 )2Zr2O7,

[0118] MgO does not participate in the chemical reaction; according to their respective molecular weights and contents, the molar ratio of the raw materials is: MgO: La2O3: Nd2O3: Sm2O3: Y2O3: Er2O3: ZrO2 = 70.76: 1: 1: 1: 1: 1: 10;

[0119] (2) Mixing: The raw materials were wet-milled for 10 h using a planetary ball mill and then dried in an oven at 60° C. Zirconia balls were used as the ball milling medium to avoid the introduction of impurities. The mass ratio of the raw materials, zirconia balls, and alcohol was as follows: raw materials: balls: alcohol = 1:1.5:2;

[0120] (3) Aging: Add 6 wt.% of PVA solution (concentration 6 wt.%) to the dried mixed raw material powder, disperse it evenly in a mortar, and then put it into a sealed bag and age it in a cool place for 1 day;

[0121] (4) Molding: The aged material is initially pressed into a disc blank with a thickness of 2-3 mm using a φ12 mm mold. The initial pressing pressure is 2 MPa and the pressure is maintained for 30 seconds. Subsequently, further isostatic pressing is performed at a pressure of 200 MPa for 3 minutes. The formed blank is then discharged in a resistance furnace at 700°C for 1 hour.

[0122] (5) Sintering: The molded green body was placed in a muffle furnace and heated to 1400°C at a rate of 5°C / min for 6 h to obtain "50wt.%MgO-50wt.% high entropy (La 1 / 5 Nd 1 / 5 Sm 1 / 5 Y 1 / 5 Er 1 / 5 )2Zr2O7" composite ceramics (50wt.% M-50wt.% LNSYEZO).

[0123] Embodiment 11:

[0124] In this example, the one-step preparation of "MgO-high entropy (A 1 / n The chemical composition of the composite ceramic inert fuel matrix is ​​designed to be 50wt.%MgO-50wt.%(La 1 / 5 Nd 1 / 5 Sm 1 / 5 Y 1 / 5 Er 1 / 5 )2Zr2O7, the preparation process of which comprises the following steps:

[0125] (1) Ingredients: MgO, La2O3, Nd2O3, Sm2O3, Y2O3, Er2O3, and ZrO2 are used as raw materials and are prepared according to the stoichiometric ratio; the following chemical reactions occur between La2O3, Nd2O3, Sm2O3, Y2O3, Er2O3, and ZrO2:

[0126] La2O3+Nd2O3+Sm2O3+Y2O3+Er2O3+10ZrO2=5(La 1 / 5 Nd 1 / 5 Sm 1 / 5 Y 1 / 5 Er 1 / 5 )2Zr2O7,

[0127] MgO does not participate in the chemical reaction; according to their respective molecular weights and contents, the molar ratio of the raw materials is: MgO: La2O3: Nd2O3: Sm2O3: Y2O3: Er2O3: ZrO2 = 70.76: 1: 1: 1: 1: 1: 10;

[0128] (2) Mixing: The raw materials were wet-milled for 10 h using a planetary ball mill and then dried in an oven at 60° C. Zirconia balls were used as the ball milling medium to avoid the introduction of impurities. The mass ratio of the raw materials, zirconia balls, and alcohol was as follows: raw materials: balls: alcohol = 1:1.5:2;

[0129] (3) Aging: Add 6 wt.% of PVA solution (concentration 6 wt.%) to the dried mixed raw material powder, disperse it evenly in a mortar, and then put it into a sealed bag and age it in a cool place for 1 day;

[0130] (4) Molding: The aged material is initially pressed into a disc blank with a thickness of 2-3 mm using a φ12 mm mold. The initial pressing pressure is 2 MPa and the pressure is maintained for 30 seconds. Subsequently, further isostatic pressing is performed at a pressure of 200 MPa for 3 minutes. The formed blank is then discharged in a resistance furnace at 700°C for 1 hour.

[0131] (5) Sintering: The molded green body was placed in a muffle furnace and heated to 1450°C at a rate of 5°C / min and kept at that temperature for 6 h to obtain "50wt.%MgO-50wt.%High Entropy (La 1 / 5 Nd 1 / 5 Sm 1 / 5 Y 1 / 5 Er 1 / 5 )2Zr2O7" composite ceramics (50wt.% M-50wt.% LNSYEZO).

[0132] Embodiment 12:

[0133] In this example, the one-step preparation of "MgO-high entropy (A 1 / n The chemical composition of the composite ceramic inert fuel matrix is ​​designed to be 50wt.%MgO-50wt.%(La 1 / 5 Nd 1 / 5 Sm 1 / 5 Y 1 / 5 Er 1 / 5 )2Zr2O7, the preparation process of which comprises the following steps:

[0134] (1) Ingredients: MgO, La2O3, Nd2O3, Sm2O3, Y2O3, Er2O3, and ZrO2 are used as raw materials and are prepared according to the stoichiometric ratio; the following chemical reactions occur between La2O3, Nd2O3, Sm2O3, Y2O3, Er2O3, and ZrO2:

[0135] La2O3+Nd2O3+Sm2O3+Y2O3+Er2O3+10ZrO2=5(La 1 / 5 Nd 1 / 5 Sm 1 / 5 Y 1 / 5 Er 1 / 5 )2Zr2O7,

[0136] MgO does not participate in the chemical reaction; according to their respective molecular weights and contents, the molar ratio of the raw materials is: MgO: La2O3: Nd2O3: Sm2O3: Y2O3: Er2O3: ZrO2 = 70.76: 1: 1: 1: 1: 1: 10;

[0137] (2) Mixing: The raw materials were wet-milled for 10 h using a planetary ball mill and then dried in an oven at 60° C. Zirconia balls were used as the ball milling medium to avoid the introduction of impurities. The mass ratio of the raw materials, zirconia balls, and alcohol was as follows: raw materials: balls: alcohol = 1:1.5:2;

[0138] (3) Aging: Add 6 wt.% of PVA solution (concentration 6 wt.%) to the dried mixed raw material powder, disperse it evenly in a mortar, and then put it into a sealed bag and age it in a cool place for 1 day;

[0139] (4) Molding: The aged material is initially pressed into a disc blank with a thickness of 2-3 mm using a φ12 mm mold. The initial pressing pressure is 2 MPa and the pressure is maintained for 30 seconds. Subsequently, further isostatic pressing is performed at a pressure of 200 MPa for 3 minutes. The formed blank is then discharged in a resistance furnace at 700°C for 1 hour.

[0140] (5) Sintering: The molded green body was placed in a muffle furnace and heated to 1500°C at a rate of 5°C / min for 3 h to obtain "50wt.%MgO-50wt.% high entropy (La 1 / 5 Nd 1 / 5 Sm 1 / 5 Y 1 / 5 Er 1 / 5 )2Zr2O7" composite ceramics (50wt.% M-50wt.% LNSYEZO).

[0141] Embodiment 13:

[0142] In this example, the one-step preparation of "MgO-high entropy (A 1 / n The chemical composition of the composite ceramic inert fuel matrix is ​​designed to be 50wt.%MgO-50wt.%(La 1 / 5 Nd 1 / 5 Sm 1 / 5 Y 1 / 5 Er 1 / 5 )2Zr2O7, the preparation process of which comprises the following steps:

[0143] (1) Ingredients: MgO, La2O3, Nd2O3, Sm2O3, Y2O3, Er2O3, and ZrO2 are used as raw materials and are prepared according to the stoichiometric ratio; the following chemical reactions occur between La2O3, Nd2O3, Sm2O3, Y2O3, Er2O3, and ZrO2:

[0144] La2O3+Nd2O3+Sm2O3+Y2O3+Er2O3+10ZrO2=5(La 1 / 5 Nd 1 / 5 Sm 1 / 5 Y 1 / 5 Er 1 / 5 )2Zr2O7,

[0145] MgO does not participate in the chemical reaction; according to their respective molecular weights and contents, the molar ratio of the raw materials is: MgO: La2O3: Nd2O3: Sm2O3: Y2O3: Er2O3: ZrO2 = 70.76: 1: 1: 1: 1: 1: 10;

[0146] (2) Mixing: The raw materials were wet-milled for 10 h using a planetary ball mill and then dried in an oven at 60° C. Zirconia balls were used as the ball milling medium to avoid the introduction of impurities. The mass ratio of the raw materials, zirconia balls, and alcohol was as follows: raw materials: balls: alcohol = 1:1.5:2;

[0147] (3) Aging: Add 6 wt.% of PVA solution (concentration 6 wt.%) to the dried mixed raw material powder, disperse it evenly in a mortar, and then put it into a sealed bag and age it in a cool place for 1 day;

[0148] (4) Molding: The aged material is initially pressed into a disc blank with a thickness of 2-3 mm using a φ12 mm mold. The initial pressing pressure is 2 MPa and the pressure is maintained for 30 seconds. Subsequently, further isostatic pressing is performed at a pressure of 200 MPa for 3 minutes. The formed blank is then discharged in a resistance furnace at 700°C for 1 hour.

[0149] (5) Sintering: The molded green body was placed in a muffle furnace and heated to 1500°C at a rate of 5°C / min for 9 hours to obtain "50wt.%MgO-50wt.% high entropy (La 1 / 5 Nd 1 / 5 Sm 1 / 5 Y 1 / 5 Er 1 / 5 )2Zr2O7" composite ceramics (50wt.% M-50wt.% LNSYEZO).

[0150] Embodiment 14:

[0151] In this example, the one-step preparation of "MgO-high entropy (A 1 / n The chemical composition of the composite ceramic inert fuel matrix is ​​designed to be 50wt.%MgO-50wt.%(La 1 / 5 Nd 1 / 5 Sm 1 / 5 Y 1 / 5 Er 1 / 5 )2Zr2O7, the preparation process of which comprises the following steps:

[0152] (1) Ingredients: MgO, La2O3, Nd2O3, Sm2O3, Y2O3, Er2O3, and ZrO2 are used as raw materials and are prepared according to the stoichiometric ratio; the following chemical reactions occur between La2O3, Nd2O3, Sm2O3, Y2O3, Er2O3, and ZrO2:

[0153] La2O3+Nd2O3+Sm2O3+Y2O3+Er2O3+10ZrO2=5(La 1 / 5 Nd 1 / 5 Sm 1 / 5 Y 1 / 5 Er 1 / 5 )2Zr2O7,

[0154] MgO does not participate in the chemical reaction; according to their respective molecular weights and contents, the molar ratio of the raw materials is: MgO: La2O3: Nd2O3: Sm2O3: Y2O3: Er2O3: ZrO2 = 70.76: 1: 1: 1: 1: 1: 10;

[0155] (2) Mixing: The raw materials were wet-milled for 10 h using a planetary ball mill and then dried in an oven at 60° C. Zirconia balls were used as the ball milling medium to avoid the introduction of impurities. The mass ratio of the raw materials, zirconia balls, and alcohol was as follows: raw materials: balls: alcohol = 1:1.5:2;

[0156] (3) Aging: Add 6 wt.% of PVA solution (concentration 6 wt.%) to the dried mixed raw material powder, disperse it evenly in a mortar, and then put it into a sealed bag and age it in a cool place for 1 day;

[0157] (4) Molding: The aged material is initially pressed into a disc blank with a thickness of 2-3 mm using a φ12 mm mold. The initial pressing pressure is 2 MPa and the pressure is maintained for 30 seconds. Subsequently, further isostatic pressing is performed at a pressure of 200 MPa for 3 minutes. The formed blank is then discharged in a resistance furnace at 700°C for 1 hour.

[0158] (5) Sintering: Place the molded green body in a muffle furnace and heat it to a temperature of 5°C / min.

[0159] Keep at 1500℃ for 12h to obtain "50wt.%MgO-50wt.%High Entropy (La 1 / 5 Nd 1 / 5 Sm 1 / 5 Y 1 / 5 Er 1 / 5 )2Zr2O7" composite ceramics (50wt.% M-50wt.% LNSYEZO).

[0160] Embodiment 15:

[0161] In this example, the one-step preparation of "MgO-medium entropy (A 1 / n The chemical composition of the composite ceramic inert fuel matrix is ​​designed to be 50wt.%MgO-50wt.%(La 1 / 3 Nd 1 / 3 Sm 1 / 3 )2Zr2O7, the preparation process of which comprises the following steps:

[0162] (1) ZrO2 treatment: ZrO2, H2O and H2O2 with a mass ratio of 1:3:5 were placed in a high-temperature and high-pressure reactor, i.e., a supercritical reactor, and stirred (speed 350 r / min) for 10 minutes under a supercritical state (temperature 350°C, pressure 30 MPa), and filtered and vacuum dried to obtain pretreated ZrO2;

[0163] (2) Ingredients: MgO, La2O3, Nd2O3, Sm2O3, and pretreated ZrO2 are used as raw materials and are prepared according to a stoichiometric ratio; wherein the following chemical reaction occurs between La2O3, Nd2O3, Sm2O3, and ZrO2: La2O3+Nd2O3+Sm2O3+6ZrO2=3(La 1 / 3 Nd 1 / 3Sm 1 / 3 )2Zr2O7, MgO did not participate in the chemical reaction; according to their respective molecular weights and contents, the molar ratio of each raw material is: MgO: La2O3: Nd2O3: Sm2O3: ZrO2 = 43.43: 1: 1: 1: 6;

[0164] (3) Mixing: The raw materials were wet-milled for 10 h using a planetary ball mill and then dried in an oven at 60° C. Zirconia balls were used as the ball milling medium to avoid the introduction of impurities. The mass ratio of the raw materials, zirconia balls, and alcohol was as follows: raw materials: balls: alcohol = 1:1.5:2;

[0165] (4) Aging: Add 6 wt.% of PVA solution (concentration: 6 wt.%) to the dried mixed raw material powder, disperse it evenly in a mortar, and then put it into a sealed bag and age it in a cool place for 1 day;

[0166] (5) Molding: The aged material is initially pressed into a disc blank with a thickness of 2-3 mm using a φ12 mm mold. The initial pressing pressure is 2 MPa and the pressure is maintained for 30 seconds. Subsequently, further isostatic pressing is performed at a pressure of 200 MPa for 3 minutes. The formed blank is then discharged in a resistance furnace at 700°C for 1 hour.

[0167] (6) Sintering: The molded green body was placed in a muffle furnace and heated to 1500°C at a rate of 5°C / min for 6 h to obtain "50wt.%MgO-50wt.% medium entropy (La 1 / 3 Nd 1 / 3 Sm 1 / 3 )2Zr2O7" composite ceramics (50wt.% M-50wt.% LNSZO).

[0168] Embodiment 16:

[0169] In this example, the one-step preparation of "MgO-medium entropy (A 1 / n The chemical composition of the composite ceramic inert fuel matrix is ​​designed to be 50wt.%MgO-50wt.%(La 1 / 4 Nd 1 / 4 Sm 1 / 4 Y 1 / 4 )2Zr2O7, the preparation process of which comprises the following steps:

[0170] (1) ZrO2 treatment: ZrO2, H2O and H2O2 with a mass ratio of 1:3:5 were placed in a high-temperature and high-pressure reactor, i.e., a supercritical reactor, and stirred (speed 350 r / min) for 10 minutes under a supercritical state (temperature 350°C, pressure 30 MPa), and filtered and vacuum dried to obtain pretreated ZrO2;

[0171] (2) Ingredients: MgO, La2O3, Nd2O3, Sm2O3, Y2O3, and pretreated ZrO2 are used as raw materials and are prepared according to the stoichiometric ratio; the following chemical reactions occur between La2O3, Nd2O3, Sm2O3, Y2O3, and ZrO2:

[0172] La2O3+Nd2O3+Sm2O3+Y2O3+8ZrO2=4(La 1 / 4 Nd 1 / 4 Sm 1 / 4 Y 1 / 4 )2Zr2O7,MgO

[0173] No chemical reaction was performed; according to their respective molecular weights and contents, the molar ratio of the raw materials was: MgO: La2O3: Nd2O3: Sm2O3: Y2O3: ZrO2 = 55.15: 1: 1: 1: 1: 8;

[0174] (3) Mixing: The raw materials were wet-milled for 10 h using a planetary ball mill and then dried in an oven at 60° C. Zirconia balls were used as the ball milling medium to avoid the introduction of impurities. The mass ratio of the raw materials, zirconia balls, and alcohol was as follows: raw materials: balls: alcohol = 1:1.5:2;

[0175] (4) Aging: Add 6 wt.% of PVA solution (concentration 6 wt.%) to the dried mixed raw material powder, disperse it evenly in a mortar, and then put it into a sealed bag and age it in a cool place for 1 day;

[0176] (5) Molding: The aged material is initially pressed into a disc blank with a thickness of 2-3 mm using a φ12 mm mold. The initial pressing pressure is 2 MPa and the pressure is maintained for 30 seconds. Subsequently, further isostatic pressing is performed at a pressure of 200 MPa for 3 minutes. The formed blank is then discharged in a resistance furnace at 700°C for 1 hour.

[0177] (6) Sintering: The molded green body was placed in a muffle furnace and heated to 1500°C at a rate of 5°C / min for 6 h to obtain "50wt.%MgO-50wt.% medium entropy (La 1 / 4 Nd 1 / 4 Sm 1 / 4 Y 1 / 4 )2Zr2O7" composite ceramics (50wt.% M-50wt.% LNSYZO).

[0178] Embodiment 17:

[0179] In this example, the one-step preparation of "MgO-high entropy (A 1 / n The chemical composition of the composite ceramic inert fuel matrix is ​​designed to be 50wt.%MgO-50wt.%(La 1 / 5 Nd 1 / 5 Sm 1 / 5 Y 1 / 5 Er 1 / 5 )2Zr2O7, the preparation process of which comprises the following steps:

[0180] (1) ZrO2 treatment: ZrO2, H2O and H2O2 with a mass ratio of 1:3:5 were placed in a high-temperature and high-pressure reactor, i.e., a supercritical reactor, and stirred (speed 350 r / min) for 10 minutes under a supercritical state (temperature 350°C, pressure 30 MPa), and filtered and vacuum dried to obtain pretreated ZrO2;

[0181] (2) Ingredients: MgO, La2O3, Nd2O3, Sm2O3, Y2O3, Er2O3, and pretreated ZrO2 are used as raw materials and are prepared according to the stoichiometric ratio; the following chemical reactions occur between La2O3, Nd2O3, Sm2O3, Y2O3, Er2O3, and ZrO2:

[0182] La2O3+Nd2O3+Sm2O3+Y2O3+Er2O3+10ZrO2=5(La 1 / 5 Nd 1 / 5 Sm 1 / 5 Y 1 / 5 Er 1 / 5 )2Zr2O7,

[0183] MgO does not participate in the chemical reaction; according to their respective molecular weights and contents, the molar ratio of the raw materials is: MgO: La2O3: Nd2O3: Sm2O3: Y2O3: Er2O3: ZrO2 = 70.76: 1: 1: 1: 1: 1: 10;

[0184] (3) Mixing: The raw materials were wet-milled for 10 h using a planetary ball mill and then dried in an oven at 60° C. Zirconia balls were used as the ball milling medium to avoid the introduction of impurities. The mass ratio of the raw materials, zirconia balls, and alcohol was as follows: raw materials: balls: alcohol = 1:1.5:2;

[0185] (4) Aging: Add 6 wt.% of PVA solution (concentration: 6 wt.%) to the dried mixed raw material powder, disperse it evenly in a mortar, and then put it into a sealed bag and age it in a cool place for 1 day;

[0186] (5) Molding: The aged material is initially pressed into a disc blank with a thickness of 2-3 mm using a φ12 mm mold. The initial pressing pressure is 2 MPa and the pressure is maintained for 30 seconds. Subsequently, further isostatic pressing is performed at a pressure of 200 MPa for 3 minutes. The formed blank is then discharged in a resistance furnace at 700°C for 1 hour.

[0187] (6) Sintering: The molded green body was placed in a muffle furnace and heated to 1500°C at a rate of 5°C / min for 6 h to obtain "50wt.%MgO-50wt.% high entropy (La 1 / 5 Nd 1 / 5 Sm 1 / 5 Y 1 / 5 )2Zr2O7" composite ceramics (50wt.% M-50wt.% LNSYEZO).

[0188] The "MgO-medium / high entropy (A)" obtained in Examples 1-17 above were respectively1 / n )2Zr2O7" composite ceramics were tested for relative density, and the results are shown in Table 1. It can be seen from Table 1 that the relative density of the prepared composite ceramics is higher than 96%, and the relative density of the composite ceramics obtained by using the pretreated zirconia is better, indicating that the pretreated zirconia can better react with the rare earth oxide raw materials and the transition metal oxides, and thus make the relative density of the prepared composite ceramics higher.

[0189] Table 1 "MgO-medium / high entropy (A 1 / n Relative density of 2Zr2O7" composite ceramics

[0190] Chemical composition of sample Sintering conditions Relative density Example 1 50wt.%M-50wt.%LNSZO 1500℃, keep warm for 6h 96.1％ Example 2 50wt.%M-50wt.%LNSYZO 1500℃, keep warm for 6h 98.0％ Example 3 50wt.%M-50wt.%LNSYEZO 1500℃, keep warm for 6h 99.0％ Example 4 20wt.%M-80wt.%LNSYEZO 1500℃, keep warm for 6h 98.3％ Example 5 30wt.%M-70wt.%LNSYEZO 1500℃, keep warm for 6h 94.4％ Example 6 40wt.%M-60wt.%LNSYEZO 1500℃, keep warm for 6h 97.0％ Example 7 60wt.%M-40wt.%LNSYEZO 1500℃, keep warm for 6h 97.6％ Example 8 70wt.%M-30wt.%LNSYEZO 1500℃, keep warm for 6h 97.6％ Example 9 80wt.%M-20wt.%LNSYEZO 1500℃, keep warm for 6h 98.1％ Example 10 50wt.%M-50wt.%LNSYEZO 1400℃, keep warm for 6h 92.9％ Embodiment 11 50wt.%M-50wt.%LNSYEZO 1450℃, keep warm for 6h 98.1％ Example 12 50wt.%M-50wt.%LNSYEZO 1500℃, keep warm for 3h 93.1％ Example 13 50wt.%M-50wt.%LNSYEZO 1500℃, keep warm for 6h 99.0％ Embodiment 14 50wt.%M-50wt.%LNSYEZO 1500℃, keep warm for 9h 99.9％ Embodiment 15 50wt.%M-50wt.%LNSZO 1500℃, keep warm for 6h 98.5％ Example 16 50wt.%M-50wt.%LNSYZO 1500℃, keep warm for 6h 99.1％ Embodiment 17 50wt.%M-50wt.%LNSYEZO 1500℃, keep warm for 6h 99.6％

[0191] In addition, all prepared “MgO-medium / high entropy (A 1 / n )2Zr2O7" composite ceramics consist of only MgO and medium / high entropy (A 1 / n )2Zr2O7 pyrochlore has two crystalline phases, typically "50wt.%MgO-50wt.%medium / high entropy (A 1 / n The phase compositions of the composite ceramic samples (n=3 / 4 / 5, referred to as 50wt.%M-50wt.%LNSZO, 50wt.%M-50wt.%LNSYZO and 50wt.%M-50wt.%LNSYEZO, prepared in Examples 1, 2 and 3) were determined by X-ray diffractometer and compared with the standard PDF cards of MgO and Nd2Zr2O7 pyrochlore. The results are shown in the attached figure. Figure 1 shown. Figure 2 For a typical "50wt.%MgO-50wt.%medium / high entropy (A 1 / n )2Zr2O7" (n=3 / 4 / 5, referred to as 50wt.%M-50wt.%LNSZO, 50wt.%M-50wt.%LNSYZO and 50wt.%M-50wt.%LNSYEZO, prepared in Examples 1, 2 and 3) cross-sectional scanning electron micrographs of composite ceramic samples, used to evaluate the "MgO-high entropy (A)" prepared by the one-step method of the present invention. 1 / n )2Zr2O7" composite ceramics and the uniformity of the two-phase distribution.

[0192] Figure 3 is part of the “ωMgO-(1-ω) high entropy (La 1 / 5 Nd 1 / 5 Sm 1 / 5 Y 1 / 5 Er 1 / 5)2Zr2O7 pyrochlore" (ω = 30 ~ 70wt.%, prepared in Examples 5, 6, 3, 7, 8) composite ceramics in the thermal expansion test process relative elongation versus temperature. The sintering conditions are 1500℃ / 6h. Figure 3 It can be seen that during the heating process from 25 to 1350 °C, "MgO-high entropy (La 1 / 5N 1 / 5 Sm 1 / 5 Y 1 / 5 Er 1 / 5 The relative elongation of the 2Zr2O7" composite ceramics is linearly related to the temperature, indicating that within this temperature range, the structure of all composite ceramic samples is stable and no phase transformation occurs. In addition, the thermal expansion coefficient of the composite ceramics is calculated according to the change curve in the figure. Table 2 lists the calculation results. It can be seen from Table 2 that with the decrease of MgO content, the thermal expansion coefficient of the composite ceramics also decreases. At 13.2×10 -6 ~14.7×10 -6 K -1 This shows that high entropy (La 1 / 5N 1 / 5 Sm 1 / 5 Y 1 / 5 Er 1 / 5 )2Zr2O7 pyrochlore effectively reduces the “MgO-high entropy (La 1 / 5 Nd 1 / 5 Sm 1 / 5 Y 1 / 5 Er 1 / 5 )2Zr2O7” composite ceramics with thermal expansion coefficient.

[0193] Figure 4 is part of the “ωMgO-(1-ω) high entropy (La 1 / 5 Nd 1 / 5 Sm 1 / 5 Y 1 / 5 Er 1 / 5 )2Zr2O7 pyrochlore" (ω=30, 50 and 70wt.%) composite ceramics prepared in Examples 5, 3 and 8. The sintering conditions are 1500℃ / 6h. Figure 4 It can be seen that in the temperature range of 25 to 1400 ° C, "MgO-high entropy (La 1 / 5 Nd 1 / 5 Sm 1 / 5 Y 1 / 5 Er 1 / 5)2Zr2O7" composite ceramics have a linear relationship with temperature; in addition, the higher the MgO content in the composite ceramics, the greater the thermal conductivity of the sample, indicating that MgO contributes more to the thermal conductivity of the composite ceramics than high-entropy pyrochlore. But in general, within this temperature range, the thermal conductivity of all composite ceramic samples exceeds the thermal conductivity of UO2 fuel and UO2-PuO2 mixed oxide fuel under the same temperature conditions.

[0194] In summary, the "MgO-high entropy (La 1 / 5 Nd 1 / 5 Sm 1 / 5 Y 1 / 5 Er 1 / 5 )2Zr2O7" composite ceramics have low thermal expansion coefficient, excellent thermal stability and thermal conductivity, and fully meet the thermal physical property requirements of inert fuel substrates.

[0195] Table 2 Components "MgO-High Entropy (La 1 / 5 Nd 1 / 5 Sm 1 / 5 Y 1 / 5 Er 1 / 5 Thermal expansion coefficient of 2Zr2O7" composite ceramics

[0196]

[0197]

[0198] Figure 4 The 500KeV He 2+ "50wt.%MgO-50wt.%High Entropy (La 1 / 5 Nd 1 / 5Sm 1 / 5 Y 1 / 5 Er 1 / 5 The GIXRD spectrum of the 2Zr2O7" composite ceramic (Example 3) at a grazing incidence angle of γ = 1.0° (where the radiation damage is the largest) is shown in Figure 2. When the radiation dose is increased from 1.0×10 16 ions / cm 2 Increase to 1.0×10 17 ions / cm 2 The corresponding dpa value increased from 0.16 to 1.55. The results show that only MgO phase and high entropy (La 1 / 5 Nd 1 / 5 Sm 1 / 5 Y 1 / 5E 1 / 5 )2Zr2O7 pyrochlore phase, and there is no obvious shift of the characteristic peaks before and after irradiation; the high entropy (La 1 / 5Nd 1 / 5 Sm 1 / 5 Y 1 / 5 Er 1 / 5 )2Zr2O7 pyrochlore phase is an ordered pyrochlore structure, and the high entropy (La 1 / 5 Nd 1 / 5 Sm 1 / 5 Y 1 / 5 Er 1 / 5 )2Zr2O7 pyrochlore phases are defective fluorite structures, and their diffraction peak intensity decreases with the increase of irradiation dose. That is, "50wt.%MgO-50wt.%High Entropy (La 1 / 5 Nd 1 / 5 Sm 1 / 5 Y 1 / 5 Er 1 / 5 )2Zr2O7" composite ceramics at several dpa doses of He 2+ Under ion irradiation, only high entropy (La 1 / 5 Nd 1 / 5 Sm 1 / 5 Y 1 / 5 Er 1 / 5 )2Zr2O7 pyrochlore phase order-disordered structural transition, and no obvious lattice expansion and amorphization occurred, indicating that the one-step preparation of the "MgO-high entropy (La 1 / 5 Nd 1 / 5 Sm 1 / 5 Y 1 / 5 Er 1 / 5 )2Zr2O7" composite ceramics have excellent radiation stability.

[0199] Figure 6 "50wt.%MgO-50wt.%Medium / High Entropy (A 1 / n )2Zr2O7(n=3 / 4 / 5)” composite ceramics composite ceramics under the same irradiation conditions (500KeV He 2+ , 1×10 17 ions / cm 2 ) and the corresponding dpa values ​​are 1.55, 1.60, and 1.62, respectively. From the characterization results, it can be found that the MgO phase and high entropy (La 1 / 5 Nd 1 / 5 Sm 1 / 5 Y 1 / 5 Er 1 / 5 )2Zr2O7 pyrochlore has no relative shift in its corresponding characteristic peaks. 2+ Under irradiation, the "MgO-medium / high entropy (A 1 / nBoth crystalline phases in the ")2Zr2O7(n=3 / 4 / 5)" composite ceramics show good radiation stability, and the relative contents of the two phases do not affect the macroscopic radiation stability of the composite ceramics.

[0200] 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 magnesium oxide-medium / high entropy zirconate pyrochlore composite ceramic inert fuel substrate, characterized in that: The general chemical formula of the magnesium oxide-medium / high entropy zirconate pyrochlore composite ceramic inert fuel substrate is: ωMgO-(1-ω)(A 1 / n )2Zr2O7, where ω represents the mass percentage, ranging from 30 to 80wt.%; n represents (A 1 / n )The number of element types at the A lattice site in the 2Zr2O7 pyrochlore, n is an integer and 3≤n≤5; at the same time, the element types are selected from La, Nd, Sm, Y, and Er, and the element types and the mass ratio of the two crystalline phases in the composite ceramic can be arbitrarily controlled.

2. The magnesium oxide-medium / high entropy zirconate pyrochlore composite ceramic inert fuel substrate according to claim 1, characterized in that: When n is 3, (A 1 / n )2Zr2O7 is medium entropy pyrochlore, A=La 1 / 3 Nd 1 / 3 Sm 1 / 3 The general chemical formula of the magnesium oxide-medium / high entropy zirconate pyrochlore composite ceramic inert fuel substrate is: ωMgO-(1-ω)(La 1 / 3 Nd 1 / 3 Sm 1 / 3 )2Zr2O7; When n is 4, (A 1 / n )2Zr2O7 is medium entropy pyrochlore, A=La 1 / 4 Nd 1 / 4 Sm 1 / 4 Y 1 / 4 The general chemical formula of the magnesium oxide-medium / high entropy zirconate pyrochlore composite ceramic inert fuel substrate is: ωMgO-(1-ω)(La 1 / 4 Nd 1 / 4 Sm 1 / 4 Y 1 / 4 )2Zr2O7; When n is 5, (A 1 / n )2Zr2O7 is a high entropy pyrochlore, A=La 1 / 5 Nd 1 / 5 Sm 1 / 5 Y 1 / 5 Er 1 / 5 The general chemical formula of the magnesium oxide-medium / high entropy zirconate pyrochlore composite ceramic inert fuel substrate is: ωMgO-(1-ω)(La 1 / 5 Nd 1 / 5 Sm 1 / 5 Y 1 / 5E 1 / 5 )2Zr2O7.

3. The magnesium oxide-medium / high entropy zirconate pyrochlore composite ceramic inert fuel substrate according to claim 2, characterized in that: The crystal phase composition of the magnesium oxide-medium / high entropy zirconate pyrochlore composite ceramic inert fuel substrate is a composite phase of two crystal phases: magnesium oxide and medium / high entropy zirconate pyrochlore.

4. The magnesium oxide-medium / high entropy zirconate pyrochlore composite ceramic inert fuel substrate according to claim 3, characterized in that: When n is 3, the crystal phase composition of the magnesium oxide-medium / high entropy zirconate pyrochlore composite ceramic inert fuel substrate is magnesium oxide and three components of medium entropy (La 1 / 3 Nd 1 / 3 Sm 1 / 3 )2Zr2O7 composite phase of two crystalline phases of pyrochlore; When n is 4, the crystal phase composition of the magnesium oxide-medium / high entropy zirconate pyrochlore composite ceramic inert fuel substrate is magnesium oxide and four-component medium entropy (La 1 / 4 Nd 1 / 4 Sm 1 / 4 Y 1 / 4 )2Zr2O7 composite phase of two crystalline phases of pyrochlore; When n is 5, the crystal phase composition of the magnesium oxide-medium / high entropy zirconate pyrochlore composite ceramic inert fuel substrate is magnesium oxide and five-component high entropy (La 1 / 5 Nd 1 / 5 Sm 1 / 5 Y 1 / 5 Er 1 / 5 )2Zr2O7 is a composite phase of two crystalline phases of pyrochlore.

5. The magnesium oxide-medium / high entropy zirconate pyrochlore composite ceramic inert fuel substrate according to claim 1, characterized in that: The relative density of the magnesium oxide-medium / high entropy zirconate pyrochlore composite ceramic inert fuel substrate reaches 93-99%.

6. A method for preparing the magnesium oxide-medium / high entropy zirconate pyrochlore composite ceramic inert fuel substrate according to any one of claims 1 to 5, characterized in that: include: The raw materials of magnesium oxide, zirconium oxide and various oxides are mixed, a binder is added, aged, formed and discharged, and then directly sintered by a solid phase reaction one-step method to prepare a magnesium oxide-medium / high entropy zirconate pyrochlore composite ceramic inert fuel substrate; wherein the various oxides are at least three of the following five oxides, and the five oxides are: lanthanum oxide, neodymium oxide, samarium oxide, erbium oxide, and yttrium oxide.

7. The method for preparing the magnesium oxide-medium / high entropy zirconate pyrochlore composite ceramic inert fuel substrate according to claim 6, characterized in that: The mixing method is ball milling mixing, and the ball milling mixing uses a planetary ball mill for wet ball milling. The ball milling time is 5 to 10 hours. The ball milling medium is zirconia balls, and the ball milling dispersant is alcohol, wherein the raw material: zirconia balls: alcohol = 1:1 to 2:1 to 3.

8. The method for preparing the magnesium oxide-medium / high entropy zirconate pyrochlore composite ceramic inert fuel substrate according to claim 6, characterized in that: The binder is a PVA solution with a concentration of 4-10 wt.%, and its usage is 5-7 wt.% of the total mass of the mixed raw materials.

9. The method for preparing the magnesium oxide-medium / high entropy zirconate pyrochlore composite ceramic inert fuel substrate as claimed in claim 6, wherein the molding is cold isostatic pressing, the molding pressure is 160-240 MPa, and the molding time is 2-5 min; the plastic discharge temperature is 550-850°C, and the insulation time is 0.5-2 h.

10. The method for preparing the magnesium oxide-medium / high entropy zirconate pyrochlore composite ceramic inert fuel substrate according to claim 6, characterized in that: The solid phase reaction one-step sintering is muffle furnace high temperature sintering, the heating rate is 3-6°C / min; the sintering temperature is 1400-1500°C, and the sintering time is 3-12h.

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