CN113264769B - High-entropy stable rare earth tantalate/niobate ceramic and preparation method thereof - Google Patents
High-entropy stable rare earth tantalate/niobate ceramic and preparation method thereof Download PDFInfo
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Abstract
The invention discloses a chairThe entropy stable rare earth tantalate/niobate ceramic and the preparation method thereof comprise the following steps: with rare earth oxide RE2O3Tantalum oxide Ta2O5Niobium oxide Nb2O5And MO2Oxide as raw material, A3BO7Type rare earth tantalum/niobate RE3Ta1‑ xNbxO7Ceramic as matrix, three or more kinds of MO are added2The oxides equally replace rare earth and tantalum/niobium elements at the A and B positions to obtain a novel high-entropy stable rare earth tantalate/niobate ceramic material RE3‑yTa1‑y/2‑xNbx‑y/2M2yO7. The ceramic material prepared by the invention has the characteristics of low thermal conductivity, high thermal expansion coefficient, high hardness, high fracture toughness, controllable crystal structure and the like, and can be used as high-temperature protective materials such as thermal barrier coatings, environmental barrier coatings, nuclear material reservoirs and the like.
Description
Technical Field
The invention relates to the technical field of high-temperature structural ceramic materials, in particular to a high-entropy stable rare earth tantalate/niobate ceramic and a preparation method thereof.
Background
The application environment of the thermal barrier coating and the environmental barrier coating requires that the ceramic has the characteristics of high melting point, excellent high-temperature stability, high hardness, high fracture toughness, low thermal conductivity, excellent heat radiation resistance, high thermal expansion coefficient and the like, and the advantages of low material preparation cost, simple preparation process, wide raw material source and the like under the condition of meeting the different conditions can promote the large-scale application of the material. A. the3BO7Type rare earth tantalate/niobate and A2B2O7The type rare earth zirconium/titanium/tin/hafnate ceramics (A site is all rare earth elements) have the advantages of low thermal conductivity, good high-temperature phase stability, high hardness and the like, but also have heatLow expansion coefficient, poor fracture toughness, insufficient heat radiation resistance and the like.
In order to solve the above problems, it is necessary to increase the concentration of lattice point defects in the material to further reduce the thermal conductivity, increase the thermal expansion coefficient by using the lattice relaxation principle, and solve the problems of poor fracture toughness, insufficient thermal radiation resistance, and the like.
Disclosure of Invention
In view of the above-mentioned shortcomings of the prior art, the present invention aims to provide a high entropy stable rare earth tantalate/niobate ceramic and a method for preparing the same, which are used to solve the problem of A in the prior art3BO7Type rare earth tantalate/niobate and A2B2O7The rare earth zirconium/titanium/tin/hafnate ceramic has the problems of low thermal expansion coefficient, poor fracture toughness, insufficient heat radiation resistance and the like.
In order to achieve the above objects and other related objects, the present invention provides, in one aspect, a method for preparing a high entropy stable rare earth tantalate/niobate ceramic, comprising the steps of:
with rare earth oxide RE2O3Tantalum oxide Ta2O5Niobium oxide Nb2O5And MO2Oxide as starting material, with A3BO7Type rare earth tantalum/niobate RE3Ta1-xNbxO7Ceramic as matrix, three or more different MOs are added2The oxides equally replace rare earth and tantalum/niobium elements at the A and B positions to obtain the compound high-entropy stable rare earth tantalate/niobate ceramic with the chemical formula of RE3-yTa1-y/2-xNbx-y/2M2yO7Wherein x is more than or equal to 1 and more than or equal to 0, and y is more than 1 and more than 0.1; wherein RE is rare earth element, M is at least one selected from Sn, Ti, Zr and Hf.
Further, by regulating the compound RE3-yTa1-y/2-xNbx-y/2M2yO7The value of x and y in the rare earth tantalum/niobate ceramic structure is realized by A3BO7Type direction A2B2O7Transformation of the form.
Further, the rare earth oxygenCompound RE2O3In the formula (I), RE is at least one selected from Y, La, Nd, Sm, Eu, Gd, Dy, Ho, Er, Tm, Yb and Lu.
Further, three or more kinds of MO having the same content (or molar ratio) are added2An oxide.
Further, the preparation method comprises the following steps:
(1) weighing the raw material RE according to the required stoichiometric ratio2O3、Ta2O5、Nb2O5And three or more different MOs2Calcining the oxide, cooling, adding a ball milling medium and a ball milling auxiliary agent, performing ball milling, drying and sieving to obtain powder after the ball milling is finished;
(2) weighing the powder sieved in the step (1) and performing discharge plasma sintering to prepare blocky high-entropy stable rare earth tantalate/niobate ceramic;
(3) and carrying out heat preservation annealing and decarbonization on the sintered block ceramic to finally obtain the compact high-entropy stable rare earth tantalate/niobate ceramic.
In the step (1), the purpose of the calcination is to remove organic impurities contained in the powder and to reduce the reactivity of the raw material powder.
Further, in the step (1), the calcination temperature is 800-1200 ℃, and the calcination time is 2-5 hours.
Further, in the step (1), the ball milling time is 12-36 hours, and the rotation speed of the ball mill is 400-600 r/min.
Further, in the step (1), the ball milling medium is zirconia balls, and the ball-to-material ratio is 1 (2-3); the ball-milling auxiliary agent is absolute ethyl alcohol, and the mass ratio of the raw materials to the ball-milling auxiliary agent is 1 (2-3).
Further, in the step (1), the drying temperature is 90-100 ℃, and the drying time is 5-8 hours.
Further, in the step (1), the powder is sieved by a 200-400 mesh sieve.
Further, in the step (2), the discharge plasma sintering conditions are as follows: 1200 ℃ and 1400 ℃, 100MPa and 4-10 min.
Further, in the step (3), the conditions of heat preservation, annealing and carbon removal are as follows: after the sintered block ceramic is cooled, the block ceramic is insulated for 2 to 6 hours at the temperature of 1000-1400 ℃.
Another aspect of the present invention provides a high entropy stable rare earth tantalate/niobate ceramic having a chemical formula of RE prepared according to the above method3-yTa1-y/2-xNbx-y/2M2yO7Wherein x is more than or equal to 1 and more than or equal to 0, and y is more than 1 and more than 0.1.
As mentioned above, the high-entropy stable rare earth tantalate/niobate ceramic and the preparation method thereof have the following beneficial effects:
the invention takes improving the configuration entropy to stabilize the crystal lattice, scattering phonon by point defect to reduce the heat conductivity, solid solution strengthening, fine crystal strengthening and the like as theoretical bases, and takes A3BO7Type rare earth tantalum/niobate RE3Ta1-xNbxO7Ceramic as matrix, by adding three or more equal amounts of MO2The oxide realizes the simultaneous equivalent substitution of the rare earth elements of the A bit elements and the B bit elements and the tantalum/niobium elements to obtain the high-entropy stable rare earth tantalum/niobate ceramic material with controllable crystal structure, and the specific chemical formula is RE3-yTa1-y/2-xNbx-y/ 2M2yO7。
1. The purpose of the step (1) is to obtain the original powder material with uniform mixing and low chemical activity, and prevent the generation of a second phase/precipitated phase in the high-temperature and high-pressure sintering process, thereby obtaining the single-phase rare earth tantalum/niobate ceramic. By regulating RE3-yTa1-y/2-xNbx-y/2M2yO7The values of x and y in the alloy can realize that the rare earth tantalum/niobate is formed by A3BO7To A2B2O7And (4) transforming the structure.
2. The purpose of the step (2) is to combine the methods of high-temperature and high-pressure spark plasma sintering rapid preparation and entropy stable structure to prevent the generation of a second phase and prepare the single-phase high-purity high-density rare earth tantalum/niobate ceramic. The high-temperature high-pressure short-time sintering can inhibit the growth of crystal grains and the generation of precipitated phases, so that the material has excellent mechanical properties.
3. The step (3) aims to remove carbon infiltrated into the ceramic material in the high-temperature sintering process, and simultaneously, the high-temperature heat-preservation annealing can eliminate internal stress, improve the purity of the ceramic material and reduce and release the internal stress.
The high-entropy stable rare earth tantalate/niobate ceramic crystal structure prepared by the invention is A3BO7Or A2B2O7Pyrochlore/fluorite type structure in RE3-yTa1-y/2-xNbx-y/2M2yO7The crystal lattice has high concentration of oxygen vacancy, density higher than 99%, and single-phase structure without generation of precipitated phase/second phase. A. the2B2O7Type rare earth zirconium/titanium/hafnium/stannate and A3BO7The crystal structures of the type rare earth tantalum/niobate ceramics are all AO2The fluorite structure is evolved, the crystal lattice can tolerate high-concentration point defects and has excellent high-temperature stability, the high-stability entropy-stable modified rare earth tantalum/niobate with a single crystal structure is obtained by utilizing a mode of simultaneously replacing the high-entropy-stable crystal lattice, the crystal structure similarity and the A site and the B site, and meanwhile, the RE is regulated and controlled3- yTa1-y/2-xNbx-y/2M2yO7The values of x and y in the alloy can realize that the rare earth tantalum/niobate is formed by A3BO7To A2B2O7And (4) transformation of the type structure. Three or more MOs added2The oxides have the same molar ratio, so that the maximization of the configuration entropy in the crystal lattice can be realized, the stabilization of the crystal lattice is further realized, the temperature and the time required by final sintering are reduced, the effects of inhibiting the growth of crystal grains and the generation of precipitated phases in quick short-time sintering are achieved, and the low-temperature quick sintering is ensured to obtain the high-density, fine-grain and single-phase rare earth tantalum/niobate ceramics. The ceramic material RE prepared by the invention3-yTa1-y/2-xNbx-y/2M2yO7The crystal lattice contains high-concentration point defects, obvious poor atomic mass, poor ionic radius and the like, phonons can be effectively scattered, the thermal conductivity can be reduced, and meanwhile, the fracture toughness of the material can be further improved by using a method of inhibiting the crystal grains from growing by solid solution strengthening and short-time sintering.
In conclusion, the ceramic material prepared by the invention has the characteristics of low thermal conductivity, high thermal expansion coefficient, high hardness, high fracture toughness, controllable crystal structure and the like, and can be used as high-temperature protection materials such as thermal barrier coatings, environmental barrier coatings, nuclear material storages and the like.
Drawings
FIG. 1 shows A obtained in examples 1 and 2 of the present invention3BO7And A2B2O7XRD diffraction pattern of type rare earth tantalum/niobate ceramic.
FIG. 2 shows A obtained in examples 1 and 2 of the present invention3BO7And A2B2O7The thermal conductivity of the rare earth tantalum/niobate ceramic has the trend of changing with temperature.
FIG. 3 shows A of different compositions3BO7And A2B2O7The type rare earth tantalum/niobate ceramic material has good fracture toughness.
Detailed Description
The following embodiments of the present invention are provided by way of specific examples, and other advantages and effects of the present invention will be readily apparent to those skilled in the art from the disclosure herein. The invention is capable of other and different embodiments and of being practiced or of being carried out in various ways, and its several details are capable of modification in various respects, all without departing from the spirit and scope of the present invention.
For the current A3BO7Type rare earth tantalate/niobate and A2B2O7The invention provides a preparation method of high-entropy stable rare earth tantalate/niobate ceramic, which comprises the following steps:
with rare earth oxide RE2O3(RE is rare earth element), tantalum oxide Ta2O5Niobium oxide Nb2O5And MO2Oxide (M is at least one selected from Sn, Ti, Zr and Hf) of (M ═ Sn, Ti, Zr and Hf) as raw material, and A3BO7Rare earth tantalum/niobateRE3Ta1-xNbxO7Ceramic as matrix, and three or more kinds of MO with same content (or molar ratio)2The oxide realizes the isometrical and equivalent substitution of the rare earth and tantalum/niobium elements at the A and B positions, and maintains the balance of the lattice electronegativity to obtain the compound high-entropy stable rare earth tantalate/niobate ceramic with the chemical formula of RE3-yTa1-y/2-xNbx-y/2M2yO7Wherein x is more than or equal to 1 and more than or equal to 0, and y is more than 1>0.1; further, by modulating the compound RE3-yTa1-y/2-xNbx-y/2M2yO7The value of x and y in the rare earth tantalum/niobate ceramic structure is realized by A3BO7Type direction A2B2O7Transformation of the form.
The invention adds three or more MO with equal quantity at the same time2The oxide maximizes the configuration entropy and simultaneously reduces the temperature required by ceramic reaction sintering, realizes the technical effect of inhibiting the growth of crystal grains by combining sintering and densification at lower temperature with a short-time sintering process, and obtains the heterovalent metal ion high-entropy stable rare earth tantalum/niobate ceramic with high fracture toughness, low thermal conductivity, high thermal expansion coefficient and controllable structure by utilizing a solid solution strengthening and fine crystal strengthening mechanism.
Further, the rare earth oxide RE2O3In the formula (I), RE is at least one selected from Y, La, Nd, Sm, Eu, Gd, Dy, Ho, Er, Tm, Yb and Lu.
Further, the preparation method comprises the following steps:
(1) weighing the raw material RE according to the required stoichiometric ratio2O3、Ta2O5、Nb2O5And three or more different MOs2Calcining an oxide, cooling, adding a ball milling medium and a ball milling aid, performing ball milling, drying and sieving after ball milling to obtain powder;
(2) weighing the powder sieved in the step (1) and performing discharge plasma sintering to prepare blocky high-entropy stable rare earth tantalate/niobate ceramic;
(3) and carrying out heat preservation annealing and decarbonization on the sintered block ceramic to finally obtain the compact high-entropy stable rare earth tantalate/niobate ceramic.
In the step (1), the purpose of the calcination is to remove organic impurities contained in the powder and to reduce the reactivity of the raw material powder.
Further, in the step (1), the calcination temperature is 800-1200 ℃ and the calcination time is 2-5 hours.
Further, in the step (1), the ball milling time is 12-36 hours, and the rotation speed of the ball mill is 400-600 r/min.
Further, in the step (1), the ball milling medium is zirconia balls, and the ball-to-material ratio is 1 (2-3); the ball milling auxiliary agent is absolute ethyl alcohol, and the mass ratio of the raw materials to the ball milling auxiliary agent is 1 (2-3).
Further, in the step (1), the drying temperature is 90-100 ℃, and the drying time is 5-8 hours.
Further, in the step (1), the powder is sieved by a 200-400-mesh sieve.
Further, in the step (2), the spark plasma sintering conditions are as follows: 1200 ℃ and 1400 ℃, 100MPa and 4-10 min.
Further, in the step (3), the conditions of heat preservation, annealing and carbon removal are as follows: after the sintered block ceramic is cooled, the block ceramic is insulated for 2 to 6 hours at the temperature of 1000-1400 ℃.
Another aspect of the present invention provides a high entropy stable rare earth tantalate/niobate ceramic having a chemical formula of RE prepared according to the above method3-yTa1-y/2-xNbx-y/2M2yO7Wherein x is more than or equal to 1 and more than or equal to 0, and y is more than 1 and more than 0.1.
The following specific exemplary examples illustrate the invention in detail. It should also be understood that the following examples are illustrative only and are not to be construed as limiting the scope of the invention, and that numerous insubstantial modifications and adaptations of the invention described above will occur to those skilled in the art. The specific process parameters and the like of the following examples are also merely examples of suitable ranges, i.e., those skilled in the art can select from suitable ranges through the description herein and are not limited to the specific values of the following examples.
Example 1
Preparation A3BO7Type Gd2.6Ta0.3Nb0.3Ti0.2Zr0.2Hf0.2Sn0.2O7The high-entropy ceramic comprises the following specific steps:
gd is taken as a raw material2O3、Ta2O5、Nb2O5And MO2Weighing the (M ═ Sn, Ti, Zr and Hf) according to a stoichiometric ratio, and then placing the weighed mixture in a high-temperature furnace for heat preservation at 1200 ℃ for 5 hours to remove organic impurities contained in the raw material powder and reduce the reactivity of the raw material powder; and then cooling the raw material powder to room temperature, placing the cooled raw material powder, alcohol and zirconia grinding balls in a ball milling tank according to the mass ratio of 1:2:3 for ball milling and mixing, wherein the rotation speed is 600 revolutions per minute and the ball milling time is 36 hours, then preserving the temperature of the uniformly mixed powder at 100 ℃ for 5 hours for drying treatment, and finally sieving the powder with 400 meshes to obtain fine powder. Weighing about 2.0g of sieved powder, placing the powder in a graphite grinding tool for development and forming, and then placing the powder in a discharge plasma sintering system for high-temperature high-pressure sintering under the sintering condition of 1400-120 MPa-10 min; after sintering, cooling, taking out the material, and carrying out annealing decarbonization treatment at 1400 ℃ for 2 hours to finally obtain the compact material A3BO7Type Gd2.6Ta0.3Nb0.3Ti0.2Zr0.2Hf0.2Sn0.2O7The high-entropy ceramic of (2).
Example 2
Preparation A2B2O7Type Yb2.5Ta0.25Nb0.25Ti0.25Zr0.25Hf0.25Sn0.25O7The method comprises the following specific steps:
mixing the raw material Yb2O3、Ta2O5、Nb2O5And MO2(M ═ Sn, Ti, Zr, Hf) was weighed in a stoichiometric ratio, and then placed in a high temperature furnace at 800 ℃ for 2 hours to remove impurities contained in the raw material powderOrganic impurities and reduces the reactivity of the raw material powder; then cooling the raw material powder to room temperature, placing the cooled and cooled raw material powder, alcohol and zirconia grinding balls in a ball milling tank according to the mass ratio of 1:2:2 for ball milling and mixing, wherein the rotating speed during ball milling is 300 revolutions per minute, the ball milling time is 12 hours, then preserving the heat of the uniformly mixed powder at 90 ℃ for 8 hours for drying treatment, and finally sieving the uniformly mixed powder by 200 meshes to obtain fine powder. Weighing about 2.0g of sieved powder, placing the powder in a graphite grinding tool for development and forming, and then placing the powder in a spark plasma sintering system for high-temperature high-pressure sintering under the sintering condition of 1200-100 MPa-4 min; after sintering, taking out the material after cooling, and carrying out annealing and carbon removal treatment at 1000 ℃ for 6 hours to finally obtain compact material A2B2O7Yb of type structure2.5Ta0.25Nb0.25Ti0.25Zr0.25Hf0.25Sn0.25O7High entropy ceramics.
FIG. 1 shows A prepared for example 13BO7Type rare earth tantalum/niobate ceramic (Gd)2.6Ta0.3Nb0.3Ti0.2Zr0.2Hf0.2Sn0.2O7) And A prepared in example 22B2O7Type rare earth tantalum/niobate ceramic (Gd)2.6Ta0.3Nb0.3Ti0.2Zr0.2Hf0.2Sn0.2O7) XRD diffractogram of (a). As is clear from FIG. 1, Gd was prepared2.6Ta0.3Nb0.3Ti0.2Zr0.2Hf0.2Sn0.2O7XRD diffraction peak of (1) and3BO7RE rare earth tantalate/niobate RE3Ta/NbO7The standard cards of the ceramics are consistent, no precipitated phase or diffraction peaks of other second phases exist, and the crystal structure of the prepared material is A3BO7And is a single-phase structure with high purity; gd (Gd)2.6Ta0. 3Nb0.3Ti0.2Zr0.2Hf0.2Sn0.2O7XRD diffraction peak of (1) and2B2O7rare earth zirconate/hafnate RE2Zr2/Hf2O7No other precipitated phase or second phase diffraction peak exists, and the crystal structure of the prepared material is A2B2O7And is a single-phase structure with high purity.
FIG. 2 shows A prepared for example 13BO7Type rare earth tantalum/niobate ceramic (Gd)2.6Ta0.3Nb0.3Ti0.2Zr0.2Hf0.2Sn0.2O7) And A prepared in example 22B2O7Type rare earth tantalum/niobate ceramic (Gd)2.6Ta0.3Nb0.3Ti0.2Zr0.2Hf0.2Sn0.2O7) The trend of thermal conductivity with temperature. As can be seen from FIG. 2, A2B2O7The thermal conductivity of the ceramic material with the structure is obviously lower than A3BO7Type A is due to3BO7The type structure is an ordered phase, and A2B2O7The structure is a long-range ordered short-range disordered phase, which shows that the effective control of the thermal conductivity of the material can be realized through component regulation, so that the material meets the performance requirements of different service environments.
Example 3
Preparation A3BO7Type Dy2.5Ta0.25Nb0.25Ti0.25Zr0.25Hf0.25Sn0.25O7The high-entropy ceramic comprises the following specific steps:
dy is taken as a raw material2O3、Ta2O5、Nb2O5And MO2(M ═ Sn, Ti, Zr, Hf) was weighed in a stoichiometric ratio, and then placed in a high temperature furnace at 1100 ℃ for 3 hours to remove organic impurities contained in the raw material powder and reduce the reactivity of the raw material powder; then cooling the raw material powder to room temperature, placing the cooled and cooled raw material powder, alcohol and zirconia grinding balls in a ball milling tank according to the mass ratio of 1:2:2 for ball milling and mixing, wherein the rotating speed during ball milling is 450 revolutions per minute, the ball milling time is 20 hours, and then preserving the heat of the uniformly mixed powder at 95 DEG CDrying for 5 hr, and sieving with 300 mesh sieve to obtain fine powder. Weighing about 2.5g of sieved powder, placing the powder in a graphite grinding tool for development and forming, and then placing the powder in a spark plasma sintering system for high-temperature high-pressure sintering under the sintering condition of 1300-110 MPa-8 min; after sintering, taking out the material after cooling, and carrying out annealing decarbonization treatment at 1200 ℃ for 4 hours to finally obtain the compact material A3BO7Dy of type2.5Ta0.25Nb0.2 5Ti0.25Zr0.25Hf0.25Sn0.25O7The high-entropy ceramics of (2).
Example 4
Preparation A2B2O7Type La2.1Ta0.25Nb0.25Ti0.35Zr0.35Hf0.35Sn0.35O7The method comprises the following specific steps:
the raw material La is added2O3、Ta2O5、Nb2O5And MO2(M ═ Sn, Ti, Zr, Hf) was weighed in a stoichiometric ratio, and then placed in a high temperature furnace at 1050 ℃ for 4 hours to remove organic impurities contained in the raw material powder and reduce the reactivity of the raw material powder; and then cooling the raw material powder to room temperature, placing the cooled raw material powder, alcohol and zirconia grinding balls in a ball milling tank according to a mass ratio of 1:2:2 for ball milling and mixing, wherein the rotation speed during ball milling is 300 revolutions per minute, the ball milling time is 30 hours, then, preserving the heat of the uniformly mixed powder at 98 ℃ for 6 hours, drying, and finally, sieving through 350 meshes to obtain fine powder. Weighing about 2.3g of sieved powder, placing the powder in a graphite grinding tool for development and forming, and then placing the powder in a spark plasma sintering system for high-temperature high-pressure sintering under the sintering condition of 1350-105 MPa-8 min; after sintering, taking out the material after cooling, and carrying out annealing and carbon removal treatment at 1300 ℃ for 4 hours to finally obtain compact material A2B2O7La of type structure2.1Ta0.25Nb0.25Ti0.35Zr0.35Hf0.35Sn0.35O7High entropy ceramics.
FIG. 3 shows A as different components3BO7And A2B2O7The type rare earth tantalum/niobate ceramic material has good fracture toughness. The samples numbered 1 and 2 on the abscissa in FIG. 3 are A of examples 2 and 4, respectively2B2O7Type structural ceramics, samples No. 3 and 4 are A of examples 1 and 3, respectively3BO7Ceramics of type structure, both of which have a fracture toughness higher than that of A of a single rare earth element3BO7Rare earth tantalate/niobate (RE) type3Ta/NbO7RE is any of rare earth elements) and A2B2O7Rare earth zirconate (RE)2Zr2O7RE is any one of rare earth elements) ceramic (1-2MPa · m)1/2) It is thus understood that ceramic materials having higher fracture toughness can be prepared by the method of the present invention, which is caused by grain refinement and solid solution strengthening effects produced during the preparation process.
The foregoing embodiments are merely illustrative of the principles and utilities of the present invention and are not intended to limit the invention. Those skilled in the art can modify or change the above-described embodiments without departing from the spirit and scope of the present invention. Accordingly, it is intended that all equivalent modifications or changes which may be made by those skilled in the art without departing from the spirit and scope of the present invention as defined in the appended claims.
Claims (5)
1. The preparation method of the high-entropy stable rare earth tantalate/niobate ceramic is characterized in that rare earth oxide RE is used2O3Tantalum oxide Ta2O5Niobium oxide Nb2O5And MO2Oxide as starting material, with A3BO7Rare earth tantalum/niobate RE3Ta1- xNbxO7Ceramic as matrix, and three or more different MOs2The oxides substitute the rare earth and tantalum/niobium elements at the A and B positions in equal quantity to obtain the compound high-entropy stable rare earth tantalate/niobate ceramic with the chemical formula of RE3-yTa1-y/2- xNbx-y/2M2yO7Wherein x is more than 0 and more than 1 and y is more than 0.1; wherein RE is rare earth element, M is selected from at least three of Sn, Ti, Zr and Hf; the preparation method comprises the following specific steps:
(1) weighing the raw material RE according to the required stoichiometric ratio2O3、Ta2O5、Nb2O5And three or more different MOs2Calcining the oxide at 800-1200 ℃ for 2-5 h; then cooling, adding a ball milling medium and a ball milling auxiliary agent, and carrying out ball milling, wherein the ball milling time is 12-36 hours, and the rotating speed of the ball mill is 400-600 r/min; after the ball milling is finished, drying the mixture for 5 to 8 hours at the temperature of between 90 and 100 ℃, and then sieving the dried mixture through a 200-400-mesh sieve to obtain powder;
the ball-milling medium is zirconia balls, and the ball-material ratio is 1 (2-3); the ball-milling auxiliary agent is absolute ethyl alcohol, and the mass ratio of the raw materials to the ball-milling auxiliary agent is 1 (2-3);
(2) weighing the powder sieved in the step (1) and performing spark plasma sintering, wherein the spark plasma sintering conditions are as follows: preparing the blocky high-entropy stable rare earth tantalate/niobate ceramic at the temperature of 1200 ℃ and 1400 ℃ and the pressure of 100MPa for 4-10 min;
(3) and carrying out heat preservation annealing and carbon removal on the sintered block ceramic, wherein the heat preservation annealing and carbon removal conditions are as follows: after the sintered block ceramic is cooled, the temperature is preserved for 2 to 6 hours at the temperature of 1000-1400 ℃, and finally the compact high-entropy stable rare earth tantalate/niobate ceramic is obtained.
2. The production method according to claim 1, characterized in that: by regulating the compound RE3-yTa1-y/2-xNbx-y/ 2M2yO7The value of x and y in the rare earth tantalum/niobate ceramic structure is realized by A3BO7Type direction A2B2O7A transformation of the form.
3. The production method according to claim 1, characterized in that: the rare earth oxide RE2O3In the formula, RE is selected from Y, La, Nd, Sm, Eu, Gd and Dy, Ho, Er, Tm, Yb and Lu.
4. The production method according to claim 1, characterized in that: adding three or more kinds of MO with the same content2An oxide.
5. A high entropy stable rare earth tantalate/niobate ceramic prepared by the method according to any one of claims 1 to 4, wherein the chemical formula is RE3-yTa1-y/2-xNbx-y/2M2yO7Wherein x is more than 0 and more than 1 and y is more than 0.1.
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