Non-equi-molar ratio high-entropy thermoelectric ceramic and preparation method thereof

Abstract

A non-equal molar ratio high-entropy thermoelectric ceramic and a preparation method thereof, chemical formula is (Ca 1 / 3 Sr 1 / 3 Ba 1 / 3 ) 1‑x La x TiO3 (x=0.1~0.4). Through pre-sintering, discharge plasma sintering and reduction annealing process, the phase composition of A-site high-entropy perovskite thermoelectric ceramic is single-phase perovskite structure, and the inside of the ceramic is equiaxed grain, which is consistent with the cubic perovskite structure grain morphology. The elements Ca, Sr, Ba, La, Ti and O in the ceramic are uniformly distributed in the ceramic, and there is no agglomeration phenomenon. The A-site non-equal molar ratio high-entropy perovskite thermoelectric ceramic (Ca 1 / 3 Sr 1 / 3 Ba 1 / 3 ) 1‑x La x TiO3 obtained by the application has low thermal conductivity, high electrical conductivity and Seebeck coefficient, and further exhibits high thermoelectric ZT value, and the operation is simple, the time period is short, and an effective path is provided for preparing high-temperature thermoelectric materials.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of high-entropy ceramics, and particularly relates to a kind of A-site non-equal-molar ratio high-entropy perovskite thermoelectric ceramic (Ca 1 / 3Sr 1 / 3 Ba 1 / 3 ) 1-x La x TiO3 and a preparation method thereof. BACKGROUND

[0002] Thermoelectric materials are a kind of functional materials that can realize the mutual conversion of heat and electricity, and have been widely used in deep space exploration, communication equipment and other fields. In order to achieve higher thermoelectric conversion efficiency, thermoelectric materials need to have high electrical conductivity, high Seebeck coefficient and low thermal conductivity. Thermoelectric ceramics have the advantages of good high-temperature stability, simple preparation process, wide variety, low cost and environmental friendliness, and have attracted widespread attention from scholars. Cubic perovskite SrTiO3 has a high melting point (2080℃), a large carrier effective mass, and an appropriate band gap (3.2eV), which has become one of the most potential n-type thermoelectric ceramic materials. However, due to its high thermal conductivity (12W / m / K at room temperature), its further development is hindered.

[0003] In 2004, the concept of "high-entropy alloy" (HEAs) was proposed, and Cantor et al. first prepared a single-phase multi-component alloy with configurational entropy stability. Since then, high-entropy engineering has been widely studied in the field of alloys. Until 2015, the entropy-stable ceramic (Mg 0.2 Zn 0.2 Co 0.2 Cu 0.2 Zn 0.2 )O was reported, and the high-entropy concept entered the field of ceramics. Drawing on and inheriting from high-entropy alloys, high-entropy ceramics are single-phase ceramics formed by four or more elements according to the principle of equal atomic ratio or near equal atomic ratio. Due to the lattice distortion effect of high-entropy ceramic structure and the dynamic lag diffusion effect, it can achieve wide scattering of phonons, thereby reducing the thermal conductivity of the material. Therefore, high-entropy engineering has become an important means to optimize the performance of thermoelectric materials. Currently, the high-entropy design of perovskite thermoelectric materials is mainly based on equal-molar design, and the research on non-equal-molar design is very rare.

[0004] In the invention with publication number CN 109607615 A, a kind of B-site high-entropy perovskite ceramic and its preparation method are proposed. The invention discloses a kind of B-site high-entropy perovskite ceramic as Ba(Zr 1 / 6 Sn 1 / 6 Ti 1 / 6 Hf 1 / 6 Nb 1 / 6 Ga1 / 6 )O3, prepared by solid phase reaction method, and the phase composition and microstructure of the material were characterized, but the material composition is equimolar high-entropy ceramic material, and the functionality of the material is not described.

[0005] In the invention with publication number CN 117776692 A, a high-entropy perovskite high-temperature negative temperature coefficient thermosensitive ceramic, a preparation method and application are disclosed. The disclosed high-entropy perovskite thermosensitive ceramic has a chemical formula of (La 0.2 Nd 0.2 Sm 0.2 Eu 0.2 A 0.2 )CrO3(A is one of Pr, Tb, Dy, Ho, Er, Yb, Lu, Y). But the material composition is equimolar high-entropy ceramic material, and the high-entropy perovskite ceramic material does not have thermoelectric properties and cannot be applied to the field of thermoelectric materials.

[0006] In the invention with publication number CN 114133215 A, an A-site high-entropy perovskite ReMnO3 thermoelectric ceramic and a preparation method thereof are disclosed. The chemical composition of the proposed A-site high-entropy perovskite thermoelectric ceramic is (Ca 0.2 Sr 0.2 Ba 0.2 Y 0.2 Nd 0.2 )MnO3 and (Ca 0.2 Sr 0.2 Ba 0.2 Y 0.2 Ho 0.2 )MnO3. The material composition is equimolar high-entropy ceramic material, but the invention does not focus on the non-equimolar high-entropy design of the thermoelectric material.

[0007] In DOI: 10.1016 / j.jeurceramsoc.2024.02.022, Yibing Zhu et al. published "Ultra-low thermal conductivity in a perovskite oxide thermoelectric through entropy engineering". In this paper, high-entropy perovskite ceramics (Ca 0.33 Sr 0.33 Ba 0.33 )(Ti 0.5- x Zr 0.5-x Nb xO3, and its thermoelectric properties are studied, the preparation of the material adopts the traditional solid phase method, and does not adopt the SPS sintering and reduction annealing process.

[0008] Currently, there is no high-entropy perovskite ceramic prepared by CaCO3, SrCO3, BaCO3, La2O3 and TiO2, and the chemical formula of the high-entropy perovskite ceramic is (Ca 1 / 3Sr 1 / 3 Ba 1 / 3 ) 1-x La x TiO3 (x=0.1-0.4), which has high electrical conductivity, high Seebeck coefficient and low thermal conductivity, and currently there is no related report on the A-site non-equimolar high-entropy perovskite thermoelectric ceramic. SUMMARY

[0009] In order to overcome the problem of low thermoelectric performance of the perovskite structure SrTiO3-based thermoelectric material, the application provides a non-equimolar high-entropy thermoelectric ceramic and a preparation method thereof.

[0010] The chemical formula of the non-equimolar high-entropy perovskite ceramic thermoelectric ceramic is (Ca 1 / 3 Sr 1 / 3 Ba 1 / 3 ) 1-x La x TiO3 (x=0.1-0.4).

[0011] The raw materials for synthesizing the (Ca 1 / 3 Sr 1 / 3 Ba 1 / 3 ) 1-x La x TiO3 are CaCO3, SrCO3, BaCO3, La2O3 and TiO2, and the particle size is micron grade and the purity is analytical pure.

[0012] The specific process for preparing (Ca 1 / 3 Sr 1 / 3 Ba 1 / 3 ) 1-x La x TiO3 is as follows:

[0013] Step 1, batching:

[0014] According to the metering ratio of each component in the chemical composition formula of the high-entropy perovskite ceramic, each initial raw material is weighed.

[0015] Step 2, ball milling:

[0016] The weighed raw material powder in step 1 is ball milled in anhydrous ethanol as the ball milling medium and zirconia balls as the ball milling beads in a polytetrafluoroethylene ball mill at a rotation speed of 250-350 r / min for 12-24 h. The weight ratio of the ball milling medium to the raw material powder is 1:1, and the weight ratio of the ball milling beads to the raw material powder is 2:1. The milled slurry is dried in an oven at a temperature of 50-60 ℃ for 3-12 h, and then ground to obtain the powder.

[0017] Step 3, calcination:

[0018] The powder obtained in step 2 is placed in a sealed crucible and heated in a high-temperature muffle furnace at a heating rate of 2-5 ℃ to 1150-1250 ℃, and then cooled to 500 ℃ at a cooling rate of 2-5 ℃, and then cooled with the furnace to obtain a high-entropy ceramic powder.

[0019] Step 4, secondary ball milling:

[0020] The high-entropy ceramic powder obtained in step 3 is subjected to secondary ball milling, and the ball milling process is the same as the first ball milling to obtain a (Ca 1 / 3 Sr 1 / 3 Ba 1 / 3 ) 1-x La x TiO3 high-entropy ceramic powder.

[0021] Step 5, spark plasma sintering:

[0022] The secondary milled powder obtained in step 4 is loaded into a graphite mold, and sintered by spark plasma sintering technology, the sintering environment is vacuum, the axial pressure of the graphite mold is 30-40 MPa, the heating rate is 100 ℃ / min, the temperature is raised to 1150-1250 ℃ and then cooled to 600 ℃ at a rate of 100 ℃ / min, and then cooled with the furnace to obtain an A-site non-equi-molar high-entropy perovskite dense ceramic.

[0023] Step 6, reduction annealing:

[0024] The ceramic obtained in step 5 is placed in an alumina crucible with graphite powder, and the crucible is placed in a tube furnace, argon is introduced, and the temperature is raised to 1200-1400 ℃ at a rate of 2-5 ℃ / min and then cooled to 600 ℃ at a rate of 100 ℃ / min, and then cooled with the furnace to obtain an A-site non-equi-molar high-entropy perovskite thermoelectric ceramic (Ca 1 / 3 Sr 1 / 3 Ba 1 / 3 ) 1-x La x TiO3.

[0025] The purpose of this invention is to propose an A-site high-entropy perovskite thermoelectric ceramic (Ca) with excellent thermoelectric properties. 1 / 3Sr 1 / 3 Ba 1 / 3 ) 1-x La x TiO3 materials and their preparation methods. This method offers advantages such as simple operation and short preparation time. The prepared high-entropy ceramics possess advantages such as high electrical conductivity, high Seebeck coefficient, and low thermal conductivity, resulting in excellent thermoelectric conversion efficiency and providing an effective pathway for the preparation of high-temperature thermoelectric materials.

[0026] Compared with the prior art, the beneficial effects achieved by the present invention are as follows:

[0027] A pure-phase A-site non-equimolar high-entropy perovskite thermoelectric ceramic was obtained. The chemical formula of this material is (Ca... 1 / 3 Sr 1 / 3Ba 1 / 3 ) 1-x La x TiO3 (x = 0.1–0.4). (Appendix) Figure 1 This demonstrates that the A-site high-entropy perovskite thermoelectric ceramics obtained by the process of this invention have a single-phase perovskite structure, without a second phase. (Attached) Figure 2 ~Attached Figure 5 This invention demonstrates the process used to obtain A-type non-equimolar ratio high-entropy perovskite ceramics (Ca). 1 / 3 Sr 1 / 3 Ba 1 / 3 ) 1-x La x Scanning electron microscope (SEM) images of the microstructure of TiO3 ceramics show that the ceramic interior consists entirely of equiaxed grains, consistent with the morphology of cubic perovskite grains. (Attached...) Figure 2 ~Attached Figure 5 This demonstrates that the elements Ca, Sr, Ba, La, Ti, and O are uniformly distributed within the ceramic, without agglomeration. (Attached) Figure 6 ~Attached Figure 9 The high-entropy perovskite thermoelectric ceramic (Ca) with non-equimolar ratio at site A obtained by the process of this invention. 1 / 3 Sr 1 / 3 Ba 1 / 3 ) 1-x La x The thermoelectric properties of TiO3 as a function of temperature, and the A-site non-equimolar ratio high-entropy perovskite thermoelectric ceramic (CaO3) obtained in this invention. 1 / 3 Sr 1 / 3 Ba 1 / 3 ) 1- x La xTiO3 has low thermal conductivity, high electrical conductivity and Seebeck coefficient, and thus exhibits high thermoelectric ZT value. BRIEF DESCRIPTION OF DRAWINGS

[0028] Figure 1 The A-site non-equimolar ratio high-entropy perovskite thermoelectric ceramic (Ca 1 / 3 Sr 1 / 3 Ba 1 / 3 ) 1-x La x X-ray diffraction pattern of TiO3.

[0029] Figure 2 The A-site non-equimolar ratio high-entropy perovskite thermoelectric ceramic (Ca 1 / 3 Sr 1 / 3 Ba 1 / 3 ) 0.9 La 0.1 Microstructure morphology diagram of TiO3 and distribution diagram of elements Ca, Sr, Ba, La and Ti in the ceramic; wherein, Figure 2 a is the microstructure morphology diagram of the A-site non-equimolar ratio high-entropy perovskite thermoelectric ceramic (Ca 1 / 3 Sr 1 / 3 Ba 1 / 3 ) 0.9 La 0.1 TiO3. Figure 2 b is the Ca element distribution diagram in the A-site non-equimolar ratio high-entropy perovskite thermoelectric ceramic (Ca 1 / 3 Sr 1 / 3 Ba 1 / 3 ) 0.9 La 0.1 TiO3. Figure 2 c is the Sr element distribution diagram in the A-site non-equimolar ratio high-entropy perovskite thermoelectric ceramic (Ca 1 / 3 Sr 1 / 3Ba 1 / 3 ) 0.9 La 0.1 TiO3. Figure 2 d is the Ba element distribution diagram in the A-site non-equimolar ratio high-entropy perovskite thermoelectric ceramic (Ca 1 / 3 Sr 1 / 3Ba 1 / 3 ) 0.9 La 0.1 TiO3. Figure 2 e is the La element distribution diagram in the A-site non-equimolar ratio high-entropy perovskite thermoelectric ceramic (Ca 1 / 3 Sr 1 / 3Ba 1 / 3) 0.9 La 0.1 TiO3 in the figure; Figure 2 f is A-site non-equi-molar ratio high-entropy perovskite thermoelectric ceramic (Ca 1 / 3 Sr 1 / 3Ba 1 / 3 ) 0.9 La 0.1 TiO3 in the figure.

[0030] Figure 3 A-site non-equi-molar ratio high-entropy perovskite thermoelectric ceramic (Ca 1 / 3 Sr 1 / 3 Ba 1 / 3 ) 0.81 La 0.19 TiO3 in the figure. Among them, Figure 3 a is A-site non-equi-molar ratio high-entropy perovskite thermoelectric ceramic (Ca 1 / 3 Sr 1 / 3 Ba 1 / 3 ) 0.81 La 0.19 TiO3 in the figure. Figure 3 b is A-site non-equi-molar ratio high-entropy perovskite thermoelectric ceramic (Ca 1 / 3 Sr 1 / 3Ba 1 / 3 ) 0.81 La 0.19 TiO3 in the figure. Figure 3 c is A-site non-equi-molar ratio high-entropy perovskite thermoelectric ceramic (Ca 1 / 3Sr 1 / 3 Ba 1 / 3 ) 0.81 La 0.19 TiO3 in the figure. Figure 3 d is A-site non-equi-molar ratio high-entropy perovskite thermoelectric ceramic (Ca 1 / 3 Sr 1 / 3 Ba 1 / 3 ) 0.81 La 0.19 TiO3 in the figure. Figure 3 e is A-site non-equi-molar ratio high-entropy perovskite thermoelectric ceramic (Ca 1 / 3 Sr 1 / 3 Ba 1 / 3 ) 0.81 La 0.19 TiO3 in the figure. Figure 3 f is A-site non-equi-molar ratio high-entropy perovskite thermoelectric ceramic (Ca1 / 3 Sr 1 / 3 Ba 1 / 3 ) 0.81 La 0.19 TiO3 in the microstructure and the distribution of elements Ca, Sr, Ba, La and Ti in the ceramic. Among them,

[0031] Figure 4 The application is A-site non-equal-molar-ratio high-entropy perovskite thermoelectric ceramic (Ca 1 / 3 Sr 1 / 3 Ba 1 / 3 ) 0.78 La 0.22 TiO3 in the microstructure and the distribution of elements Ca, Sr, Ba, La and Ti in the ceramic. Among them, Figure 4 a is A-site non-equal-molar-ratio high-entropy perovskite thermoelectric ceramic (Ca 1 / 3 Sr 1 / 3 Ba 1 / 3 ) 0.78 La 0.22 TiO3 in the microstructure; Figure 4 b is A-site non-equal-molar-ratio high-entropy perovskite thermoelectric ceramic (Ca 1 / 3 Sr 1 / 3Ba 1 / 3 ) 0.78 La 0.22 TiO3 in the microstructure; Figure 4 c is A-site non-equal-molar-ratio high-entropy perovskite thermoelectric ceramic (Ca 1 / 3Sr 1 / 3 Ba 1 / 3 ) 0.78 La 0.22 TiO3 in the microstructure; Figure 4 d is A-site non-equal-molar-ratio high-entropy perovskite thermoelectric ceramic (Ca 1 / 3 Sr 1 / 3 Ba 1 / 3 ) 0.78 La 0.22 TiO3 in the microstructure; Figure 4 e is A-site non-equal-molar-ratio high-entropy perovskite thermoelectric ceramic (Ca 1 / 3 Sr 1 / 3 Ba 1 / 3 ) 0.78 La 0.22 TiO3 in the microstructure; Figure 4 f is A-site non-equal-molar-ratio high-entropy perovskite thermoelectric ceramic (Ca 1 / 3 Sr 1 / 3 Ba 1 / 3 ) 0.78 La 0.22Ti element distribution map in TiO3.

[0032] Figure 5 A-site non-equimolar ratio high-entropy perovskite ceramic (Ca 1 / 3 Sr 1 / 3 Ba 1 / 3 ) 0.6 La 0.4 TiO3 microstructure morphology map and element Ca, Sr, Ba, La and Ti distribution map in the ceramic. Among them, Figure 5 a is A-site non-equimolar ratio high-entropy perovskite thermoelectric ceramic (Ca 1 / 3 Sr 1 / 3 Ba 1 / 3 ) 0.6 La 0.4 TiO3 microstructure morphology map; Figure 5 b is A-site non-equimolar ratio high-entropy perovskite thermoelectric ceramic (Ca 1 / 3 Sr 1 / 3 Ba 1 / 3 ) 0.6 La 0.4 Ca element distribution map in TiO3; Figure 5 c is A-site non-equimolar ratio high-entropy perovskite thermoelectric ceramic (Ca 1 / 3 Sr 1 / 3 Ba 1 / 3 ) 0.6 La 0.4 Sr element distribution map in TiO3; Figure 5 d is A-site non-equimolar ratio high-entropy perovskite thermoelectric ceramic (Ca 1 / 3 Sr 1 / 3 Ba 1 / 3 ) 0.6 La 0.4 Ba element distribution map in TiO3; Figure 5 e is A-site non-equimolar ratio high-entropy perovskite thermoelectric ceramic (Ca 1 / 3 Sr 1 / 3 Ba 1 / 3 ) 0.6 La 0.4 La element distribution map in TiO3; Figure 5 f is A-site non-equimolar ratio high-entropy perovskite thermoelectric ceramic (Ca 1 / 3 Sr 1 / 3 Ba 1 / 3 ) 0.6 La 0.4 Ti element distribution map in TiO3.

[0033] Figure 6The change curve of the thermal conductivity of the CaCO3, SrCO3, BaCO3, La2O3, TiO2 made A site non-equal molar ratio high-entropy perovskite thermoelectric ceramic (Ca 1 / 3 Sr 1 / 3 Ba 1 / 3 ) 0.9 La 0.1 TiO3, (Ca 1 / 3 Sr 1 / 3 Ba 1 / 3 ) 0.81 La 0.19 TiO3, (Ca 1 / 3 Sr 1 / 3 Ba 1 / 3 ) 0.78 La 0.22 TiO3, (Ca 1 / 3 Sr 1 / 3 Ba 1 / 3 ) 0.6 La 0.4 TiO3.

[0034] Figure 7 The change curve of the thermal conductivity of the CaCO3, SrCO3, BaCO3, La2O3, TiO2 made A site non-equal molar ratio high-entropy perovskite thermoelectric ceramic (Ca 1 / 3 Sr 1 / 3 Ba 1 / 3 ) 0.9 La 0.1 TiO3, (Ca 1 / 3 Sr 1 / 3 Ba 1 / 3 ) 0.81 La 0.19 TiO3, (Ca 1 / 3 Sr 1 / 3 Ba 1 / 3 ) 0.78 La 0.22 TiO3, (Ca 1 / 3 Sr 1 / 3 Ba 1 / 3 ) 0.6 La 0.4 TiO3.

[0035] Figure 8 The change curve of the thermal conductivity of the CaCO3, SrCO3, BaCO3, La2O3, TiO2 made A site non-equal molar ratio high-entropy perovskite thermoelectric ceramic (Ca 1 / 3 Sr 1 / 3 Ba 1 / 3 ) 0.9 La 0.1 TiO3, (Ca 1 / 3 Sr1 / 3 Ba 1 / 3 ) 0.81 La 0.19 TiO3, (Ca 1 / 3 Sr 1 / 3 Ba 1 / 3 ) 0.78 La 0.22 TiO3, (Ca 1 / 3 Sr 1 / 3 Ba 1 / 3 ) 0.6 La 0.4 The Seebeck coefficient of TiO3 as a function of temperature.

[0036] Figure 9 The present invention relates to a high-entropy perovskite thermoelectric ceramic (CaCO3, SrCO3, BaCO3, La2O3, TiO2) with a non-equimolar ratio at the A-site, made of CaCO3, SrCO3, BaCO3, La2O3, and TiO2. 1 / 3 Sr 1 / 3 Ba 1 / 3 ) 0.9 La 0.1 TiO3, (Ca 1 / 3 Sr 1 / 3 Ba 1 / 3 ) 0.81 La 0.19 TiO3, (Ca 1 / 3 Sr 1 / 3 Ba 1 / 3 ) 0.78 La 0.22 TiO3, (Ca 1 / 3 Sr 1 / 3 Ba 1 / 3 ) 0.6 La 0.4 The thermoelectric ZT figure of merit of TiO3 as a function of temperature.

[0037] Figure 10 This is a flowchart of the present invention.

[0038] In the picture:

[0039] 1 is (Ca) 1 / 3 Sr 1 / 3 Ba 1 / 3 ) 0.6 La 0.4 X-ray diffraction pattern of TiO3;

[0040] 2 is (Ca) 1 / 3 Sr 1 / 3 Ba 1 / 3 ) 0.78 La 0.22 X-ray diffraction pattern of TiO3;

[0041] 3 is (Ca)1 / 3 Sr 1 / 3 Ba 1 / 3 ) 0.81 La 0.19 X-ray diffraction pattern of TiO3;

[0042] 4 is (Ca 1 / 3 Sr 1 / 3 Ba 1 / 3 ) 0.9 La 0.1 X-ray diffraction pattern of TiO3;

[0043] 5 is SrTiO3 standard PDF card # 84-0444;

[0044] 6 is (Ca 1 / 3 Sr 1 / 3 Ba 1 / 3 ) 0.78 La 0.22 Thermal conductivity of TiO3 as a function of temperature;

[0045] 7 is (Ca 1 / 3 Sr 1 / 3 Ba 1 / 3 ) 0.9 La 0.1 Thermal conductivity of TiO3 as a function of temperature;

[0046] 8 is (Ca 1 / 3 Sr 1 / 3 Ba 1 / 3 ) 0.81 La 0.19 Thermal conductivity of TiO3 as a function of temperature;

[0047] 9 is (Ca 1 / 3 Sr 1 / 3 Ba 1 / 3 ) 0.6 La 0.4 Thermal conductivity of TiO3 as a function of temperature;

[0048] 10 is (Ca 1 / 3 Sr 1 / 3 Ba 1 / 3 ) 0.78 La 0.22 Electrical conductivity of TiO3 as a function of temperature;

[0049] 11 is (Ca 1 / 3 Sr 1 / 3 Ba 1 / 3 ) 0.81 La 0.19 Electrical conductivity of TiO3 as a function of temperature;

[0050] 12 is (Ca 1 / 3 Sr 1 / 3 Ba 1 / 3 ) 0.9 La 0.1 TiO3as a function of temperature;

[0051] 13 is (Ca 1 / 3 Sr 1 / 3 Ba 1 / 3 ) 0.6 La 0.4 TiO3as a function of temperature;

[0052] 14 is (Ca 1 / 3 Sr 1 / 3 Ba 1 / 3 ) 0.6 La 0.4 TiO3as a function of temperature;

[0053] 15 is (Ca 1 / 3 Sr 1 / 3 Ba 1 / 3 ) 0.78 La 0.22 TiO3as a function of temperature;

[0054] 16 is (Ca 1 / 3 Sr 1 / 3 Ba 1 / 3 ) 0.81 La 0.19 TiO3as a function of temperature;

[0055] 17 is (Ca 1 / 3 Sr 1 / 3 Ba 1 / 3 ) 0.9 La 0.1 TiO3as a function of temperature;

[0056] 18 is (Ca 1 / 3 Sr 1 / 3 Ba 1 / 3 ) 0.81 La 0.19 TiO3as a function of temperature;

[0057] 19 is (Ca 1 / 3 Sr 1 / 3 Ba 1 / 3 ) 0.78 La 0.22 TiO3as a function of temperature;

[0058] 20 is (Ca 1 / 3Sr 1 / 3 Ba 1 / 3 ) 0.9 La 0.1 The curve of the thermoelectric ZT figure of merit of TiO3 as a function of temperature;

[0059] 21 is (Ca 1 / 3 Sr 1 / 3 Ba 1 / 3 ) 0.6 La 0.4 The curve of the thermoelectric ZT figure of merit of TiO3 as a function of temperature. DETAILED DESCRIPTION

[0060] The present application is an A-site non-equimolar ratio high-entropy perovskite thermoelectric ceramic, and its actual features will be described in detail through four embodiments. The chemical composition of the A-site non-equimolar ratio high-entropy perovskite thermoelectric ceramic is (Ca 1 / 3 Sr 1 / 3 Ba 1 / 3 ) 0.6～ 0.9 La 0.1～0.4 TiO3.

[0061] The raw reagents used in each embodiment are all commercially available analytical pure products. Table 1 is the chemical composition formula and the amount of raw materials used in each embodiment.

[0062] Table 1 Chemical composition formula and raw material amount of each embodiment

[0063]

[0064]

[0065] Embodiment 1

[0066] An A-site non-equimolar ratio high-entropy perovskite thermoelectric ceramic, the chemical composition of the A-site non-equimolar ratio high-entropy perovskite thermoelectric ceramic is (Ca 1 / 3 Sr 1 / 3 Ba 1 / 3 ) 0.9 La 0.1 TiO3.

[0067] A preparation method of an A-site non-equimolar ratio high-entropy perovskite thermoelectric ceramic (Ca 1 / 3 Sr 1 / 3 Ba 1 / 3 ) 0.9 La 0.1 TiO3, comprising the following steps:

[0068] Step 1, batching.

[0069] According to (Ca 1 / 3 Sr 1 / 3Ba 1 / 3 ) 0.9 La 0.1 The raw materials are accurately weighed according to the stoichiometric ratio of the chemical formula.

[0070] Step 2, ball milling.

[0071] Anhydrous ethanol and ball milling beads are added to the raw material powder weighed in step 1, and the mixture is ball milled in a polytetrafluoroethylene material ball mill tank at a speed of 250 r / min for 12 h. The slurry after ball milling is placed in an oven and dried at 50℃ for 12 h, and then ground into powder. The particle size of the powder is 2-4 μm.

[0072] The mass ratio of the anhydrous ethanol to the raw material is 1:1, and the mass ratio of the ball milling beads to the raw material is 2:1.

[0073] Step 3, pre-sintering.

[0074] The powder obtained in step 2 is placed in a high-temperature muffle furnace, and the temperature is raised to 1200℃ at a rate of 3℃ / min and then maintained for 2 h for pre-sintering. After the holding period, the temperature is lowered to 500℃ at a rate of 4℃ / min, and the furnace is cooled to room temperature to obtain (Ca 1 / 3Sr 1 / 3 Ba 1 / 3 ) 0.9 La 0.1 TiO3 high-entropy ceramic powder.

[0075] Step 4, secondary ball milling.

[0076] The (Ca 1 / 3 Sr 1 / 3 Ba 1 / 3 ) 0.9 La 0.1 TiO3 high-entropy ceramic powder obtained in step 3 is subjected to secondary ball milling, and the ball milling process is the same as that in step 2 to obtain (Ca 1 / 3 Sr 1 / 3 Ba 1 / 3 ) 0.9 La 0.1 TiO3 high-entropy ceramic powder with an average particle size of 3.4 μm.

[0077] Step 5, spark plasma sintering.

[0078] The powder obtained after secondary ball milling is loaded into a graphite mold, and sintering is performed by spark plasma sintering process. The sintering environment is vacuum, the axial pressure of the graphite mold is 30 MPa, the temperature is raised to 1150℃ at a rate of 100℃ / min and then maintained for 3 min. After the holding period, the temperature is lowered to 600℃ at a rate of 100℃ / min, and the furnace is cooled to room temperature to obtain A-site non-equi-molar ratio high-entropy perovskite dense ceramic (Ca 1 / 3 Sr1 / 3 Ba 1 / 3 ) 0.9 La 0.1 TiO3.

[0079] Step 6, reduction annealing.

[0080] The graphite powder was added into the alumina crucible. The obtained ceramic was placed in the alumina crucible; and the crucible was placed in the tube furnace. The tube furnace was connected with argon, and was heated to 1200℃ at a rate of 2℃ / min, and was kept for 4h. The A-site non-equimolar ratio high-entropy perovskite thermoelectric ceramic (Ca 1 / 3 Sr 1 / 3 Ba 1 / 3 ) 0.9 La 0.1 TiO3.

[0081] The phase composition of the A-site non-equimolar ratio high-entropy perovskite thermoelectric ceramic (Ca 1 / 3 Sr 1 / 3 Ba 1 / 3 ) 0.9 La 0.1 TiO3obtained according to the above steps was as shown in FIG. 1; the internal microstructure morphology of the ceramic and the distribution of Ca, Sr, Ba, La and Ti elements were as shown in FIG. 2; the curve of the thermal conductivity of the ceramic with temperature was as shown in FIG. 3; the curve of the electrical conductivity of the ceramic with temperature was as shown in FIG. 4; the curve of the Seebeck coefficient of the ceramic with temperature was as shown in FIG. 5; and the curve of the ZT value of the ceramic with temperature was as shown in FIG. 6. Figure 1 Figure 2 Figure 6 Figure 7 Figure 8 Figure 9

[0082] Example 2

[0083] An A-site non-equimolar ratio high-entropy perovskite thermoelectric ceramic, the chemical composition of the A-site non-equimolar ratio high-entropy perovskite thermoelectric ceramic being (Ca 1 / 3 Sr 1 / 3 Ba 1 / 3 ) 0.81 La 0.19 TiO3.

[0084] A preparation method of an A-site non-equimolar ratio high-entropy perovskite thermoelectric ceramic (Ca 1 / 3 Sr 1 / 3 Ba 1 / 3 ) 0.81 La 0.19 TiO3, comprising the following steps:

[0085] Step 1, batching.

[0086] According to (Ca​​​​​​1 / 3 Sr 1 / 3 Ba 1 / 3 ) 0.81 La 0.19 The stoichiometric ratio of the chemical formula of TiO3 is accurately weighed.

[0087] Step 2, ball milling.

[0088] Anhydrous ethanol and ball milling beads are added to the raw material powder weighed in step 1, and the mixture is ball milled in a polytetrafluoroethylene material ball mill tank at a speed of 300 r / min for 16 h. The slurry after ball milling is placed in an oven and dried at 53℃ for 5 h, and then ground into powder. The particle size of the powder is 2-4 μm.

[0089] The mass ratio of the anhydrous ethanol to the raw material is 1:1, and the mass ratio of the ball milling beads to the raw material is 2:1.

[0090] Step 3, pre-sintering.

[0091] The powder obtained in step 2 is placed in a high-temperature muffle furnace, and the temperature is raised to 1150℃ at a rate of 5℃ / min for pre-sintering, and the temperature is kept for 4 h. After the temperature holding is completed, the temperature is lowered to 500℃ at a rate of 2℃ / min, and the furnace is cooled to room temperature. The (Ca 1 / 3 Sr 1 / 3Ba 1 / 3 ) 0.81 La 0.19 TiO3 high-entropy ceramic powder.

[0092] Step 4, secondary ball milling.

[0093] The (Ca 1 / 3 Sr 1 / 3 Ba 1 / 3 ) 0.81 La 0.19 TiO3 high-entropy ceramic powder obtained in step 3 is subjected to secondary ball milling, and the ball milling process is the same as that in step 2. The average particle size of the (Ca 1 / 3 Sr 1 / 3 Ba 1 / 3 ) 0.81 La 0.19 TiO3 high-entropy ceramic powder.

[0094] Step 5, spark plasma sintering.

[0095] The secondary ball-milled powder obtained in step 4 is loaded into a graphite mold, and sintering is performed by a spark plasma sintering technique, with a vacuum sintering environment, an axial pressure of 35 MPa applied to the graphite mold by a pressure head, a heating rate of 100 ℃ / min, and a holding time of 5 min at 1200 ℃. Then, the temperature is decreased to 600 ℃ at a rate of 100 ℃ / min, and the furnace is cooled to obtain A-site non-equimolar high-entropy perovskite dense ceramic (Ca 1 / 3 Sr 1 / 3 Ba 1 / 3 ) 0.81 La 0.19 TiO3.

[0096] Step 6, reduction annealing.

[0097] The ceramic obtained in step 5 is placed in an alumina crucible with added graphite powder, and the crucible is placed in a tube furnace. Argon is introduced, and the temperature is increased to 1400 ℃ at a rate of 3 ℃ / min and held for 8 h. An A-site non-equimolar high-entropy perovskite thermoelectric ceramic (Ca 1 / 3 Sr 1 / 3 Ba 1 / 3 ) 0.81 La 0.19 TiO3.

[0098] An A-site non-equimolar high-entropy perovskite thermoelectric ceramic (Ca 1 / 3 Sr 1 / 3 Ba 1 / 3 ) 0.81 La 0.19 TiO3 ceramic is obtained according to the above steps, and the phase composition thereof is as shown in Figure 1 ; the internal microstructure morphology and the distribution of Ca, Sr, Ba, La, and Ti elements of the ceramic are as shown in Figure 3 ; the curve of the thermal conductivity of the ceramic with temperature is as shown in Figure 6 ; the curve of the electrical conductivity of the ceramic with temperature is as shown in Figure 7 ; the curve of the Seebeck coefficient of the ceramic with temperature is as shown in Figure 8 ; and the curve of the ZT value of the ceramic with temperature is as shown in Figure 9 .

[0099] Example 3

[0100] An A-site non-equimolar high-entropy perovskite thermoelectric ceramic, which has a chemical composition of (Ca 1 / 3 Sr 1 / 3 Ba 1 / 3 ) 0.78 La 0.22 TiO3.

[0101] An A-site non-equimolar high-entropy perovskite thermoelectric ceramic (Ca1 / 3 Sr 1 / 3 Ba 1 / 3 ) 0.78 La 0.22 TiO3, comprising the following steps:

[0102] Step 1, batching.

[0103] According to the stoichiometric ratio of the chemical formula of (Ca 1 / 3 Sr 1 / 3 Ba 1 / 3 ) 0.78 La 0.22 TiO3, the raw materials are accurately weighed.

[0104] Step 2, ball milling.

[0105] Anhydrous ethanol and ball milling beads are added to the raw material powder weighed in step 1, and ball milling is carried out in a polytetrafluoroethylene material ball milling tank at a speed of 350 r / min for 20 h. After ball milling, the slurry is placed in an oven and dried at 56℃ for 3 h, then ground into powder, and the powder particle size is 2-4 μm.

[0106] The mass ratio of anhydrous ethanol to raw materials is 1:1, and the mass ratio of ball milling beads to raw materials is 2:1.

[0107] Step 3, pre-burning.

[0108] The powder obtained in step 2 is placed in a high-temperature muffle furnace, and the temperature is raised to 1200℃ at a rate of 5℃ / min for pre-burning, and the temperature is kept for 4 h. After the holding period, the temperature is lowered to 500℃ at a rate of 4℃ / min, and the furnace is cooled to room temperature, obtaining (Ca 1 / 3 Sr 1 / 3Ba 1 / 3 ) 0.78 La 0.22 TiO3 high-entropy ceramic powder.

[0109] Step 4, secondary ball milling.

[0110] The (Ca 1 / 3 Sr 1 / 3 Ba 1 / 3 ) 0.78 La 0.22 TiO3 high-entropy ceramic powder obtained in step 3 is subjected to secondary ball milling, and the ball milling process is the same as step 2, obtaining (Ca 1 / 3 Sr 1 / 3 Ba 1 / 3 ) 0.78 La 0.22 TiO3 high-entropy ceramic powder.

[0111] Step 5, spark plasma sintering.

[0112] The secondary ball-milled powder obtained in step 4 was loaded into a graphite mold, and sintered by a spark plasma sintering technique, with a vacuum sintering environment, an axial pressure of 40 MPa applied to the graphite mold by a pressure head, a heating rate of 100℃ / min, and a holding time of 3 min at 1250℃. Then, the temperature was decreased to 600℃ at a rate of 100℃ / min, and the furnace was cooled down to obtain a non-equimolar ratio high-entropy perovskite dense ceramic (Ca 1 / 3 Sr 1 / 3 Ba 1 / 3 ) 0.78 La 0.22 TiO3.

[0113] Step 6, reduction annealing.

[0114] The ceramic obtained in step 5 was placed in an alumina crucible with added graphite powder, and the crucible was placed in a tube furnace, and argon was introduced. The temperature was increased to 1300℃ at a rate of 4℃ / min, and the holding time was 6 h. A non-equimolar ratio high-entropy perovskite thermoelectric ceramic (Ca 1 / 3 Sr 1 / 3 Ba 1 / 3 ) 0.78 La 0.22 TiO3 was obtained according to the above steps. The phase composition of the ceramic is shown in FIG. 6; the internal microstructure and the distribution of Ca, Sr, Ba, La and Ti elements are shown in FIG. 7; the curve of the thermal conductivity of the ceramic with temperature is shown in FIG. 8; the curve of the electrical conductivity of the ceramic with temperature is shown in FIG. 9; the curve of the Seebeck coefficient of the ceramic with temperature is shown in FIG. 10; and the curve of the ZT value of the ceramic with temperature is shown in FIG. 11.

[0115] A non-equimolar ratio high-entropy perovskite thermoelectric ceramic (Ca 1 / 3 Sr 1 / 3 Ba 1 / 3 ) 0.78 La 0.22 TiO3 ceramic was obtained according to the above steps. The phase composition of the ceramic is shown in FIG. 6; the internal microstructure and the distribution of Ca, Sr, Ba, La and Ti elements are shown in FIG. 7; the curve of the thermal conductivity of the ceramic with temperature is shown in FIG. 8; the curve of the electrical conductivity of the ceramic with temperature is shown in FIG. 9; the curve of the Seebeck coefficient of the ceramic with temperature is shown in FIG. 10; and the curve of the ZT value of the ceramic with temperature is shown in FIG. 11. Figure 1 Figure 4 Figure 6 Figure 7 Figure 8 Figure 9

[0116] Example 4

[0117] A non-equimolar ratio high-entropy perovskite thermoelectric ceramic, which has a chemical composition of (Ca 1 / 3 Sr 1 / 3 Ba 1 / 3 ) 0.6 La 0.4 TiO3.

[0118] ​​​​​​A-site non-equimolar ratio high-entropy perovskite thermoelectric ceramic (Ca 1 / 3 Sr 1 / 3 Ba 1 / 3 ) 0.6 La 0.4 TiO3 and a preparation method thereof, comprising the following steps:

[0119] Step 1, batching.

[0120] According to the stoichiometric ratio of the chemical formula of (Ca 1 / 3 Sr 1 / 3 Ba 1 / 3 ) 0.6 La 0.4 TiO3, the raw materials are accurately weighed.

[0121] Step 2, ball milling.

[0122] Anhydrous ethanol and ball milling beads are added to the raw material powder weighed in step 1, and the mixture is ball milled in a polytetrafluoroethylene material ball mill tank at a speed of 320 r / min for 24 h. The slurry after ball milling is placed in an oven and dried at 60℃ for 7 h, and then ground into powder. The particle size of the powder is 2-4 μm.

[0123] The mass ratio of the anhydrous ethanol to the raw materials is 1:1, and the mass ratio of the ball milling beads to the raw materials is 2:1.

[0124] Step 3, pre-sintering.

[0125] The powder obtained in step 2 is placed in a high-temperature muffle furnace, and the temperature is raised to 1250℃ at a rate of 3℃ / min for pre-sintering, and the temperature is kept for 4 h. After the temperature holding is completed, the temperature is lowered to 500℃ at a rate of 3℃ / min, and the furnace is cooled to room temperature. (Ca 1 / 3 Sr 1 / 3Ba 1 / 3 ) 0.6 La 0.4 TiO3 high-entropy ceramic powder is obtained.

[0126] Step 4, secondary ball milling.

[0127] The (Ca 1 / 3 Sr 1 / 3 Ba 1 / 3 ) 0.6 La 0.4 TiO3 high-entropy ceramic powder obtained in step 3 is subjected to secondary ball milling, and the ball milling process is the same as that in step 2. (Ca 1 / 3 Sr 1 / 3 Ba 1 / 3 ) 0.6 La 0.4 TiO3 high-entropy ceramic powder with an average particle size of 3.4 μm is obtained.

[0128] Step 5, spark plasma sintering.

[0129] The secondary ball-milled powder obtained in Step 4 was loaded into a graphite mold and sintered by spark plasma sintering technology. The sintering environment was vacuum, the axial pressure given by the pressure head to the graphite mold was 30 MPa, the heating rate was 100°C / min, the temperature was raised to 1250°C and kept for 7 min, then the temperature was lowered to 600°C at a rate of 100°C / min and the furnace was cooled, to obtain A-site non-equimolar high-entropy perovskite dense ceramic (Ca 1 / 3 Sr 1 / 3 Ba 1 / 3 ) 0.6 La 0.4 TiO3.

[0130] Step 6, reduction annealing.

[0131] The ceramic obtained in Step 5 was placed in an alumina crucible with graphite powder added, and the crucible was placed in a tube furnace, argon was introduced, and the temperature was raised to 1400°C at a rate of 5°C / min and kept for 8 h. A-site non-equimolar high-entropy perovskite thermoelectric ceramic (Ca 1 / 3 Sr 1 / 3 Ba 1 / 3 ) 0.6 La 0.4 TiO3.

[0132] Table 2 Chemical composition of each example

[0133]

[0134] Table 3 Process parameters of each example

[0135]

[0136]

[0137] Table 4 Average particle size of (Ca 1 / 3 Sr 1 / 3 Ba 1 / 3 ) 0.6 La 0.4 TiO3 high-entropy ceramic powder obtained in each example

[0138]

[0139]

[0140] A-site non-equimolar high-entropy perovskite thermoelectric ceramic (Ca 1 / 3 Sr 1 / 3 Ba 1 / 3 ) 0.6 La 0.4TiO3, the phase composition of which is shown in Figure 1 ; the internal microstructure and the distribution of Ca, Sr, Ba, La and Ti elements of the ceramic are shown in Figure 5 ; the curve of the thermal conductivity of the ceramic with temperature is shown in Figure 6 ; the curve of the electrical conductivity of the ceramic with temperature is shown in Figure 7 ; the curve of the Seebeck coefficient of the ceramic with temperature is shown in Figure 8 ; and the curve of the ZT value of the ceramic with temperature is shown in Figure 9 .

[0141] Phase structure determination of the non-equimolar ratio A-site high-entropy perovskite structure ceramic:

[0142] X-ray diffraction (XRD) is used to analyze the phase of the A-site non-equimolar ratio high-entropy perovskite thermoelectric ceramic. The instrument used is X'Pert PRO diffractometer of Netherlands Analytical Instruments Company, the scanning angle range is 2θ=10-90°, the scanning speed is 5° / min, the step is 0.01°, and the obtained powder diffraction result is shown in Figure 1 .

[0143] Micro-morphology and element distribution determination of the A-site non-equimolar ratio high-entropy perovskite thermoelectric ceramic:

[0144] The focused ion / electron dual-beam electron microscope (FIB: Helios G4 CX) of the United States FEI Company is used to observe the micro-morphology of the section of the A-site non-equimolar ratio high-entropy perovskite thermoelectric ceramic sample. The electric refrigeration spectrometer (Energy dispersive spectrometer, abbreviated as EDS: Thermo NS7) of Thermofisher Company is used to test the distribution state of various elements possibly existing in the observed area of the electron microscope, as shown in Figures 2-5 . It can be seen from Figures 2-5 that the A-site non-equimolar ratio high-entropy perovskite thermoelectric ceramic described in the application has complete crystal grains and uniform distribution of elements Ca, Sr, Ba, La and Ti.

[0145] Thermal conductivity determination of the non-equimolar ratio A-site high-entropy perovskite structure ceramic:

[0146] The LFA-427 type laser thermal conductivity tester of Germany Netzsch Company is used to directly test the thermal diffusivity α of the A-site non-equimolar ratio high-entropy perovskite thermoelectric ceramic, and the specific heat capacity C p calculated according to the calculation formula, the size of the sample is Φ12.7mm×lmm, and the thermal conductivity of the sample is obtained according to the thermal conductivity calculation formula κ=α×C p ×ρ.

[0147] A-site non-equimolar ratio high-entropy perovskite thermoelectric ceramic electrical conductivity and Seebeck coefficient determination:

[0148] The electrical conductivity and Seebeck coefficient of the A-site non-stoichiometric high-entropy perovskite thermoelectric ceramics were simultaneously measured by using the thermal-electric parameters testing system (Namicro-03) from Wuhan Jia Yitong, the temperature range was from room temperature to 1073K, the heating rate was 10K / min, and the testing environment was vacuum.

[0149] The A-site non-stoichiometric high-entropy perovskite thermoelectric ceramics (Ca 1 / 3 Sr 1 / 3 Ba 1 / 3 ) 1-x La x The thermoelectric properties of the A-site non-stoichiometric high-entropy perovskite thermoelectric ceramics (Ca

[0150] Table 3. The thermoelectric properties of the A-site non-stoichiometric high-entropy perovskite thermoelectric ceramics at 1073K

[0151]

Claims

1. A non-stoichiometric ratio high-entropy thermoelectric ceramic, characterized in that, The chemical formula of the non-equimolar ratio high-entropy perovskite ceramic thermoelectric ceramic is (Ca 1 / 3 Sr 1 / 3 Ba 1 / 3 ) 1-x La x TiO3, x = 0.1-0.4, x≠0.

25.

2. The non-stoichiometric high-entropy thermoelectric ceramic of claim 1, wherein, Ca 1 / 3 Sr 1 / 3Ba 1 / 3 ) 1-x La x TiO3are CaCO3, SrCO3, BaCO 3, La2O3, TiO2, and the particle size is micron level, and the purity is analytical pure.

3. A method of preparing the non-stoichiometric ratio high-entropy thermoelectric ceramic of claim 1, wherein, The specific process is: Step 1, batching: According to the measured ratio of each component in the chemical composition formula of the high-entropy perovskite ceramic, the initial raw materials are weighed; Step 2, powder preparation: The weighed raw material powder is ball milled with anhydrous ethanol as the ball milling medium and zirconia balls as the ball milling beads, and a slurry is obtained after ball milling; the slurry is dried and ground to obtain a powder; Step 3, pre-sintering: The obtained powder is placed in a closed crucible and pre-fired in a high-temperature muffle furnace to obtain (Ca 1 / 3 Sr 1 / 3 Ba 1 / 3 ) 1-x La x TiO3 high-entropy ceramic powder; Step 4, secondary ball milling: The obtained (Ca 1 / 3 Sr 1 / 3 Ba 1 / 3 ) 1-x La x TiO3 high-entropy ceramic powder is subjected to secondary ball milling, and the ball milling process is the same as that for preparing the powder in step 2; and the high-entropy ceramic powder with an average particle size of 2.7-3.4 μm is obtained. Step 5, spark plasma sintering: (Ca 1 / 3 Sr 1 / 3 Ba 1 / 3 ) 1-x La x TiO3 high-entropy ceramic powder is loaded into a graphite mold, and sintering is carried out through a spark plasma sintering process to obtain A-site non-equi-molar high-entropy perovskite dense ceramics. Step 6, reduction annealing: The obtained ceramic is placed in an alumina crucible with added graphite powder, and the crucible is placed in a tube furnace, argon is introduced, and annealing is carried out; a non-equi-molar ratio high-entropy perovskite thermoelectric ceramic (Ca 1 / 3 Sr 1 / 3 Ba 1 / 3 ) 1-x La x TiO3.

4. The method for preparing non-equimolar ratio high-entropy thermoelectric ceramics as described in claim 3, characterized in that, When the powder is prepared, the weight ratio of the ball milling medium to the raw material powder is 1:1, and the weight ratio of the ball milling beads to the raw material powder is 2:

1.

5. The method for preparing non-equimolar ratio high-entropy thermoelectric ceramics as described in claim 3, characterized in that, When the powder is prepared, the rotation speed of the ball mill is 250-350 r / min, the ball milling time is 12-24 h, the drying temperature is 50-60℃, and the drying time is 3-12 h.

6. The method of claim 3, wherein the non-stoichiometric ratio of the high-entropy thermoelectric ceramic is prepared by the steps of: mixing the first and second precursor powders to form a mixture; and sintering the mixture to form the non-stoichiometric ratio of the high-entropy thermoelectric ceramic. When pre-sintering, the heating rate is 2-5℃, the pre-sintering temperature is 1150-1250℃, the holding time is 2-4 h, the cooling rate is 2-5℃, and the cooling temperature is 500℃.

7. The method for preparing non-equimolar ratio high-entropy thermoelectric ceramics as described in claim 3, characterized in that, When spark plasma sintering, the sintering environment is vacuum, the axial pressure of the graphite mold given by the pressure head is 30-40 MPa, the heating rate is 100℃ / min, and the temperature is kept at 1150-1250℃ for 3-7 min; after cooling to 600℃ at a rate of 100℃ / min, the furnace is cooled.

8. The method for preparing non-equimolar ratio high-entropy thermoelectric ceramics as described in claim 3, characterized in that, When reduction annealing, the annealing temperature is 1200-1400℃, the heating rate of the tube furnace is 2-5℃ / min, and the holding time is 4-8 h.

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