High-pressure rapid preparation method and application of AB-site high-entropy strontium titanate block thermoelectric material

Abstract

The invention discloses a high-pressure rapid preparation method and application of an AB-site high-entropy strontium titanate block thermoelectric material.The AB-site high-entropy strontium titanate block thermoelectric material belongs to the technical field of thermoelectric materials.The high-pressure rapid preparation method comprises the following steps that raw materials containing Sr, Ca, Ba, La, Ti, Nb, Zr and Hf are weighed according to the molar ratio of all elements in the molecular formula of the AB-site high-entropy strontium titanate block thermoelectric material; grinding and mixing to obtain a mixture; carrying out cold press molding on the mixture to obtain a green body; and after the blank is assembled, the blank is placed in cubic high-pressure equipment for high-temperature and high-pressure sintering, and the AB-site high-entropy strontium titanate block thermoelectric material is obtained. Wherein the synthesis pressure of the high-temperature and high-pressure sintering is 3-5 GPa, the temperature is 950-1100 DEG C, and the sintering time is 0.5-2 hours. The AB-site high-entropy strontium titanate block thermoelectric material prepared by the invention has the advantages of high densification degree, no impurity phase, high mechanical property, high hardness, low thermal conductivity and the like, is a thermoelectric material with good thermoelectric performance, and has a better application prospect.

Description

Technical Field

[0001] The present invention relates to the technical field of thermoelectric materials, and specifically to a high-pressure rapid preparation method and application of an AB-site high-entropy strontium titanate bulk thermoelectric material. Background Art

[0002] With the increasing demand for sustainable energy, the development of thermoelectric materials with high-efficiency energy conversion performance has become an important research direction in materials science. The performance of thermoelectric materials is mainly determined by the dimensionless figure of merit zT = S 2 σT / κ, where S, σ, κ, and T are the Seebeck coefficient, electrical conductivity, thermal conductivity, and absolute temperature, respectively. Achieving the optimal zT value requires finding a balance among the parameters: including the complex interaction among physical parameters such as high electrical conductivity (σ) similar to metals, large Seebeck coefficient (S) of ceramic materials, and low thermal conductivity (κ) of glass materials, which makes it very difficult to simultaneously optimize the transport properties of carriers and phonons. This remains a key problem in improving thermoelectric performance. So far, chalcogenides including V2VI3 and IV-VI compounds have become the main candidate materials for solid-state refrigeration and electricity in the low-temperature and medium-temperature fields. Despite their significant potential, these materials are limited in practical applications by toxicity, easy oxidation, and high production costs, thus hindering their wide promotion.

[0003] In addition, chalcogenides with excellent zT values usually have sub-valence bonds. Oxide thermoelectric ceramics have attracted much attention in the field of power generation in high-temperature environments due to their environmental protection characteristics, excellent chemical and thermal stability, and advantages suitable for large-scale production. Although some p-type oxide ceramics (such as Ca3Co4O9, BiCuSeO, and NaCo2O4, etc.) have made significant progress, the thermoelectric performance of n-type oxide ceramics is relatively low, which limits the good matching and development of n-type and p-type components in thermoelectric devices. Efforts are being made to develop n-type oxide materials with comparable zT values to further expand the application scope of oxide-based TE devices. It is worth noting that for SrTiO3-based materials with a perovskite structure, oxide TE materials have obvious advantages, can achieve large temperature gradients in high-temperature air applications, and have the potential for large-scale production. Due to their highly symmetric crystal structure, the materials have high degeneracy and a significant Seebeck coefficient, and excellent performance, gradually becoming a promising candidate material for n-type thermoelectric applications.

[0004] However, the strong metal-oxygen ionic bonds in SrTiO3 result in a relatively high thermal conductivity at room temperature. A typical oxide material has attracted great interest as an n-type material. SrTiO3 has a perovskite crystal structure because it has a large effective mass and Seebeck coefficient. Therefore, various nanostructuring and synthesis strategies have been adopted to address the issue of high thermal conductivity by enhancing phonon scattering at different scales. Entropy engineering designs materials with different atomic sizes and properties of components, leading to severe lattice distortion and reduced phonon velocity. Restricted atomic diffusion also results in supersaturated solid solutions and fine precipitates at a local short range, thereby reducing the role of high-frequency phonons in thermal conductivity. The multi-scale defects caused by entropy engineering, including point defects, strain fields, and high-density grain boundaries, contribute to the reduction of thermal conductivity in all samples. In summary, the method of preparing bulk strontium titanate thermoelectric materials by cubic anvil high-temperature and high-pressure has great advantages and cost performance. Summary of the Invention

[0005] The purpose of the present invention is to provide a high-pressure and rapid preparation method for A-site and B-site high-entropy bulk strontium titanate thermoelectric materials to solve the problems presented in the above-mentioned background technology.

[0006] To achieve the above purpose, the embodiments of the present invention provide the following technical solutions:

[0007] A high-pressure and rapid preparation method for A-site and B-site high-entropy bulk strontium titanate thermoelectric materials, wherein the A-site of strontium titanate in the A-site and B-site high-entropy bulk strontium titanate thermoelectric materials is replaced by La, Ca, and Ba, and the B-site is replaced by Nb, Zr, and Hf;

[0008] The high-pressure and rapid preparation method for A-site and B-site high-entropy bulk strontium titanate thermoelectric materials includes the following steps:

[0009] Weigh raw materials containing Sr, Ca, Ba, La, Ti, Nb, Zr, and Hf according to the molar ratio of each element in the molecular formula of the A-site and B-site high-entropy bulk strontium titanate thermoelectric materials, and grind and mix them to obtain a mixed material;

[0010] Cold press the mixed material into a green body;

[0011] After assembling the green body, place it in a cubic anvil high-pressure device for high-temperature and high-pressure sintering to obtain the A-site and B-site high-entropy bulk strontium titanate thermoelectric materials; among them, the synthesis pressure for high-temperature and high-pressure sintering is 3-5 GPa, the temperature is 950 °C - 1100 °C, and the sintering time is 0.5 - 2 h.

[0012] Preferably, the raw materials containing Sr, Ca, Ba, La, Ti, Nb, Zr, and Hf include SrO, CaO, BaO, La2O3, TiO2, Nb2O3, ZrO2, and HfO2.

[0013] Preferably, SrO, CaO, BaO, La2O3, TiO2, Nb2O3, ZrO2, and HfO2 are added in the form of powders, and their purities are not less than 99.9%.

[0014] Preferably, the green body is in the shape of a cylinder.

[0015] Preferably, the molecular formula of the AB-site high-entropy strontium titanate bulk thermoelectric material is Sr 0.6 La 0.2 Ca 0.1 Ba 0.1 Ti 0.6 Nb 0.2 Zr 0.1 Hf 0.1 O3.

[0016] Another object of the present invention is to provide an AB-site high-entropy strontium titanate bulk thermoelectric material prepared by the above high-pressure rapid preparation method, which can reduce its thermal conductivity.

[0017] Another object of the present invention is to provide an application of the above AB-site high-entropy strontium titanate bulk thermoelectric material in the mutual conversion of thermal energy and electrical energy.

[0018] The high-pressure rapid preparation method provided by the present invention can synthesize an AB-site high-entropy strontium titanate bulk thermoelectric material with low thermal conductivity in a short time. During the synthesis process, the grains are not easy to grow, the heat is evenly distributed, and there is no hysteresis reaction, which can effectively reduce the thermal conductivity of the material, thereby effectively avoiding the problems of easy grain size growth and serious agglomeration in the traditional synthesis method. The AB-site high-entropy strontium titanate bulk thermoelectric material prepared by the present invention has the advantages of high densification degree, no impurity phase, high mechanical properties, high hardness, and low thermal conductivity. It is a thermoelectric material with good thermoelectric performance and has good application prospects. Description of the Drawings

[0019] Figure 1 It is a physical picture of the AB-site high-entropy strontium titanate bulk thermoelectric material prepared in Examples 1-6 of the present invention;

[0020] Figure 2 It is a scanning electron microscope picture of the AB-site high-entropy strontium titanate bulk thermoelectric material prepared in Examples 1-6 of the present invention;

[0021] Figure 3 It is an X-ray diffraction pattern of the AB-site high-entropy strontium titanate bulk thermoelectric material prepared in Examples 3-6 of the present invention;

[0022] Figure 4 It is the thermal diffusivity at different temperatures of the AB-site high-entropy strontium titanate bulk thermoelectric material prepared in Example 6 of the present invention;

[0023] Figure 5 Thermal conductivities at different temperatures of the A-B site high-entropy strontium titanate bulk thermoelectric material prepared in Example 6 of the present invention. Detailed implementation manners

[0024] Next, in combination with the embodiments of the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0025] Example 1: This example provides an A-B site high-entropy strontium titanate bulk thermoelectric material, in which the A site of strontium titanate is replaced by La, Ca, and Ba, and the B site is replaced by Nb, Zr, and Hf; specifically, the molecular formula of the A-B site high-entropy strontium titanate bulk thermoelectric material is Sr 0.6 La 0.2 Ca 0.1 Ba 0.1 Ti 0.6 Nb 0.2 Zr 0.1 Hf 0.1 O3.

[0026] The high-pressure rapid preparation method of the A-B site high-entropy strontium titanate bulk thermoelectric material includes the following steps:

[0027] S1. Weigh SrO, CaO, BaO, La2O3, TiO2, Nb2O3, ZrO2, and HfO2 powders (all are commercially available products with a purity of not less than 99.9%) according to the molar ratio of each element in the molecular formula of the above A-B site high-entropy strontium titanate bulk thermoelectric material, and place them in an agate mortar for thorough grinding and mixing for 1 h to obtain a mixed material.

[0028] S2. Place the mixed material in a mold and perform cold pressing at 3 MPa to obtain a cylindrical blank with a size of 10.5 mm × 4 mm.

[0029] S3. Assemble the above cylindrical billets into a high-pressure assembly. Among them, the outermost layer of the high-pressure assembly is wrapped by pyrophyllite blocks, the center of the periphery is a steel cap, further inside are copper sheets and graphite sheets, and further inside is a sintered cylindrical lining tube composed of a composite of magnesium oxide and aluminum oxide. There is a layer of graphite closely attached to the inner wall of its inner layer. The two ends of the lining tube are sealed by plugs composed of a composite sintering of magnesium oxide and aluminum oxide. The inside is the sample (cylindrical billet). The sample is protected by molybdenum and insulating rings on the periphery. Then, place the high-pressure assembly in the synthesis cavity of a six-sided top high-pressure device (CHPA, SPD-6×1200) and perform high-temperature and high-pressure sintering for 60 minutes, and then cool down and release the pressure to obtain the AB-site high-entropy strontium titanate bulk thermoelectric material. Among them, the synthesis pressure of the high-temperature and high-pressure sintering is 3 GPa, and the temperature is 1000 °C.

[0030] Example 2: This example provides an AB-site high-entropy strontium titanate bulk thermoelectric material, in which the A-site of strontium titanate is replaced by La, Ca, and Ba, and the B-site is replaced by Nb, Zr, and Hf. Specifically, the molecular formula of the AB-site high-entropy strontium titanate bulk thermoelectric material is Sr 0.6 La 0.2 Ca 0.1 Ba 0.1 Ti 0.6 Nb 0.2 Zr 0.1 Hf 0.1 O3.

[0031] The high-pressure rapid preparation method of the AB-site high-entropy strontium titanate bulk thermoelectric material includes the following steps:

[0032] S1. Weigh SrO, CaO, BaO, La2O3, TiO2, Nb2O3, ZrO2, and HfO2 powders (all are commercially available products with a purity of not less than 99.9%) according to the molar ratio of each element in the molecular formula of the above AB-site high-entropy strontium titanate bulk thermoelectric material, and place them in an agate mortar for thorough grinding and mixing for 1 h to obtain a mixed material.

[0033] S2. Place the mixed material in a mold and perform cold pressing and forming under the condition of 3 MPa to obtain a cylindrical billet of 10.5 mm × 4 mm.

[0034] S3. Assemble the above cylindrical blank into a high-pressure assembly. Among them, the outermost layer of the high-pressure assembly is wrapped by pyrophyllite blocks, the center of the periphery is a steel cap, further inside are copper sheets and graphite sheets, and further inside is a sintered cylindrical lining tube composed of a composite of magnesium oxide and aluminum oxide. There is a layer of graphite closely attached to the inner wall of its inner layer. The two ends of the lining tube are closed by plugs sintered from a composite of magnesium oxide and aluminum oxide. The inside is the sample (cylindrical blank). The sample is protected by molybdenum and insulating rings on the periphery. Then, place the high-pressure assembly in the synthesis cavity of a six-sided top high-pressure device (CHPA, SPD-6×1200) and perform high-temperature and high-pressure sintering for 60 minutes, and then cool down and relieve pressure to obtain the AB-site high-entropy strontium titanate bulk thermoelectric material. Among them, the synthesis pressure for high-temperature and high-pressure sintering is 4 GPa, and the temperature is 1000 °C.

[0035] Example 3: This example provides an AB-site high-entropy strontium titanate bulk thermoelectric material, in which the A-site of strontium titanate is replaced by La, Ca, and Ba, and the B-site is replaced by Nb, Zr, and Hf. Specifically, the molecular formula of the AB-site high-entropy strontium titanate bulk thermoelectric material is Sr 0.6 La 0.2 Ca 0.1 Ba 0.1 Ti 0.6 Nb 0.2 Zr 0.1 Hf 0.1 O3.

[0036] The high-pressure rapid preparation method of the AB-site high-entropy strontium titanate bulk thermoelectric material includes the following steps:

[0037] S1. Weigh SrO, CaO, BaO, La2O3, TiO2, Nb2O3, ZrO2, and HfO2 powders (all are commercially available products with a purity of not less than 99.9%) according to the molar ratio of each element in the molecular formula of the above AB-site high-entropy strontium titanate bulk thermoelectric material, and place them in an agate mortar for thorough grinding and mixing for 1 h to obtain a mixed material.

[0038] S2. Place the mixed material in a mold and perform cold pressing and forming under the condition of 3 MPa to obtain a cylindrical blank with a size of 10.5 mm×4 mm.

[0039] S3. Assemble the above cylindrical blank into a high-pressure assembly. Among them, the outermost layer of the high-pressure assembly is wrapped by pyrophyllite blocks, the center of the periphery is a steel cap, then inside are copper sheets and graphite sheets, and then inside is a sintered cylindrical liner composed of a composite of magnesium oxide and aluminum oxide. There is a layer of graphite closely attached to the inner wall of its inner layer. The two ends of the liner are sealed by plugs sintered from a composite of magnesium oxide and aluminum oxide. Inside is the sample (cylindrical blank). The sample is protected by molybdenum and insulating rings on the periphery. Then, place the high-pressure assembly in the synthesis cavity of a six-sided top high-pressure device (CHPA, SPD-6×1200) and conduct high-temperature and high-pressure sintering for 60 minutes, and then cool down and release the pressure to obtain the AB-site high-entropy strontium titanate bulk thermoelectric material. Among them, the synthesis pressure of the high-temperature and high-pressure sintering is 5 GPa, and the temperature is 950 °C.

[0040] Example 4: This example provides an AB-site high-entropy strontium titanate bulk thermoelectric material, in which the A-site of strontium titanate is replaced by La, Ca, and Ba, and the B-site is replaced by Nb, Zr, and Hf. Specifically, the molecular formula of the AB-site high-entropy strontium titanate bulk thermoelectric material is Sr 0.6 La 0.2 Ca 0.1 Ba 0.1 Ti 0.6 Nb 0.2 Zr 0.1 Hf 0.1 O3.

[0041] The high-pressure rapid preparation method of the AB-site high-entropy strontium titanate bulk thermoelectric material includes the following steps:

[0042] S1. Weigh SrO, CaO, BaO, La2O3, TiO2, Nb2O3, ZrO2, and HfO2 powders (all are commercially available products with a purity of not less than 99.9%) according to the molar ratio of each element in the molecular formula of the above AB-site high-entropy strontium titanate bulk thermoelectric material, and place them in an agate mortar for thorough grinding and mixing for 1 h to obtain a mixed material.

[0043] S2. Place the mixed material in a mold and conduct cold pressing and forming under the condition of 3 MPa to obtain a cylindrical blank with a size of 10.5 mm×4 mm.

[0044] S3. Assemble the above cylindrical blank into a high-pressure assembly. Among them, the outermost layer of the high-pressure assembly is wrapped by pyrophyllite blocks, the center of the periphery is a steel cap, further inside are copper sheets and graphite sheets, and further inside is a sintered cylindrical liner composed of a composite of magnesium oxide and aluminum oxide. There is a layer of graphite closely attached to the inner wall of its inner layer. The two ends of the liner are sealed by plugs composed of a composite sintering of magnesium oxide and aluminum oxide. The inside is the sample (cylindrical blank). The sample is protected by molybdenum and insulating rings on the periphery. Then, place the high-pressure assembly in the synthesis cavity of a six-sided top high-pressure device (CHPA, SPD-6×1200) and perform high-temperature and high-pressure sintering for 60 minutes, and then cool down and release the pressure to obtain the AB-site high-entropy strontium titanate bulk thermoelectric material. Among them, the synthesis pressure of the high-temperature and high-pressure sintering is 5 GPa, and the temperature is 1000 °C.

[0045] Example 5: This example provides an AB-site high-entropy strontium titanate bulk thermoelectric material, in which the A-site of strontium titanate is replaced by La, Ca, and Ba, and the B-site is replaced by Nb, Zr, and Hf. Specifically, the molecular formula of the AB-site high-entropy strontium titanate bulk thermoelectric material is Sr 0.6 La 0.2 Ca 0.1 Ba 0.1 Ti 0.6 Nb 0.2 Zr 0.1 Hf 0.1 O3.

[0046] The high-pressure rapid preparation method of the AB-site high-entropy strontium titanate bulk thermoelectric material includes the following steps:

[0047] S1. Weigh SrO, CaO, BaO, La2O3, TiO2, Nb2O3, ZrO2, and HfO2 powders (all are commercially available products with a purity of not less than 99.9%) according to the molar ratio of each element in the molecular formula of the above AB-site high-entropy strontium titanate bulk thermoelectric material, and place them in an agate mortar for thorough grinding and mixing for 1 h to obtain a mixed material.

[0048] S2. Place the mixed material in a mold and perform cold pressing at 3 MPa to obtain a cylindrical blank of 10.5 mm × 4 mm.

[0049] S3. Assemble the above cylindrical blank into a high-pressure assembly. Among them, the outermost layer of the high-pressure assembly is wrapped by pyrophyllite blocks, the center of the periphery is a steel cap, then inside are copper sheets and graphite sheets, and then inside is a sintered cylindrical liner composed of a composite of magnesium oxide and aluminum oxide. There is a layer of graphite closely attached to the inner wall of its inner layer. The two ends of the liner are sealed by plugs sintered from a composite of magnesium oxide and aluminum oxide. Inside is the sample (cylindrical blank). The periphery of the sample is protected by molybdenum and insulating rings. Then, place the high-pressure assembly in the synthesis cavity of a six-sided top high-pressure device (CHPA, SPD-6×1200) and perform high-temperature and high-pressure sintering for 60 minutes, and then cool down and release the pressure to obtain the AB-site high-entropy strontium titanate bulk thermoelectric material. Among them, the synthesis pressure for high-temperature and high-pressure sintering is 5 GPa, and the temperature is 1050 °C.

[0050] Example 6: This example provides an AB-site high-entropy strontium titanate bulk thermoelectric material, in which the A-site of strontium titanate is replaced by La, Ca, and Ba, and the B-site is replaced by Nb, Zr, and Hf. Specifically, the molecular formula of the AB-site high-entropy strontium titanate bulk thermoelectric material is Sr 0.6 La 0.2 Ca 0.1 Ba 0.1 Ti 0.6 Nb 0.2 Zr 0.1 Hf 0.1 O3.

[0051] The high-pressure rapid preparation method of the AB-site high-entropy strontium titanate bulk thermoelectric material includes the following steps:

[0052] S1. Weigh SrO, CaO, BaO, La2O3, TiO2, Nb2O3, ZrO2, and HfO2 powders (all are commercially available products with a purity of not less than 99.9%) according to the molar ratio of each element in the molecular formula of the above AB-site high-entropy strontium titanate bulk thermoelectric material, and place them in an agate mortar for thorough grinding and mixing for 1 h to obtain a mixed material.

[0053] S2. Place the mixed material in a mold and perform cold pressing at 3 MPa to obtain a cylindrical blank with a size of 10.5 mm × 4 mm.

[0054] S3. Assemble the above cylindrical blank into a high-pressure assembly. Among them, the outermost layer of the high-pressure assembly is wrapped by pyrophyllite blocks, the center of the periphery is a steel cap, then there are copper sheets and graphite sheets, and then there is a sintered cylindrical liner composed of a composite of magnesium oxide and aluminum oxide. There is a layer of graphite closely attached to the inner wall of its inner layer. The two ends of the liner are sealed by plugs sintered from a composite of magnesium oxide and aluminum oxide. The inside is the sample (cylindrical blank). The sample is protected by molybdenum and insulating rings on the periphery. Then, place the high-pressure assembly in the synthesis cavity of a six-sided top high-pressure device (CHPA, SPD-6×1200) and perform high-temperature and high-pressure sintering for 60 min, and then cool down and release the pressure to obtain the AB-site high-entropy strontium titanate bulk thermoelectric material. Among them, the synthesis pressure for high-temperature and high-pressure sintering is 5 GPa, and the temperature is 1100 °C.

[0055] Use the AB-site high-entropy strontium titanate bulk thermoelectric materials prepared in Examples 1-6 as samples for the following analysis:

[0056] I. The physical pictures of the samples prepared in Examples 1-6 are as Figure 1 shown (from left to right, from top to bottom, they are the physical pictures of the AB-site high-entropy strontium titanate bulk thermoelectric materials prepared in Examples 1-6 in sequence). The samples are small round wafers with a diameter of 10 mm and a height of 4 mm.

[0057] II. First, polish the surface of the sample with sandpaper. Then, use a wire cutting machine (STX-202A, China) to cut the 4-mm-thick sample into a 1-mm-high thin slice and another 3-mm-high original slice. Use the laser flash method (CLA) to measure the thermal diffusivity D of one of the 1-mm-thick samples, and calculate the heat capacity C of the sample through the Dulong-Petit law p , and measure the density ρ of the sample by the Archimedes principle using an electronic balance (AE124J, China). Calculate the thermal conductivity of the sample using κ = ρC p D. The results are as Figure 4 and Figure 5 shown. The other sample is used for other test characterizations.

[0058] III. To detect the phase structure of the sample, use an X-ray diffractometer (XRD, Rigaku D / Max 2550V / PC, Japan Cu-Kα radiation, λ = 0.15418 nm) to measure the change of 2θ from 20° to 80°, and a field emission scanning electron microscope (SEM, FEI Magellan, America). The results are as Figure 2 and Figure 3 shown.

[0059] In summary, the high-pressure rapid preparation method provided by the embodiments of the present invention can synthesize an A-site and B-site high-entropy strontium titanate bulk thermoelectric material with low thermal conductivity in a short time. During the synthesis process, the grains are not prone to grow, the heat is evenly distributed, and there is no hysteresis reaction, which can effectively improve the thermoelectric performance of the material, thus effectively avoiding the problems of easy grain size growth and serious agglomeration in the traditional synthesis method. Therefore, the A-site and B-site high-entropy strontium titanate bulk thermoelectric material prepared by the present invention is a thermoelectric material with good thermoelectric performance and has good application prospects.

[0060] Based on the ideal embodiments of the present invention described above, through the above description, relevant workers can completely make various changes and modifications without departing from the technical idea of the present invention. The technical scope of the present invention is not limited to the content in the specification.

Claims

1. A method for rapidly preparing a high-entropy strontium titanate bulk thermoelectric material with AB sites by high pressure, characterized in that, In the ABO high-entropy strontium titanate bulk thermoelectric material, the A-site of strontium titanate is replaced by La, Ca, and Ba, and the B-site is replaced by Nb, Zr, and Hf; The high-pressure rapid preparation method of the ABO high-entropy strontium titanate bulk thermoelectric material comprises the following steps: Weigh raw materials containing Sr, Ca, Ba, La, Ti, Nb, Zr, and Hf according to the molar ratio of each element in the molecular formula of the ABO high-entropy strontium titanate bulk thermoelectric material, and grind and mix them to obtain a mixture; Cold-press the mixture to form a green body; After assembling the green body, place it in a six-sided top high-pressure device for high-temperature and high-pressure sintering to obtain the ABO high-entropy strontium titanate bulk thermoelectric material; wherein, the synthesis pressure for high-temperature and high-pressure sintering is 3-5 GPa, the temperature is 950 °C - 1100 °C, and the sintering time is 0.5-2 h.

2. The high-pressure rapid preparation method of the AB-site high-entropy strontium titanate bulk thermoelectric material according to claim 1, characterized in that The raw materials containing Sr, Ca, Ba, La, Ti, Nb, Zr, and Hf include SrO, CaO, BaO, La2O3, TiO2, Nb2O3, ZrO2, and HfO2.

3. The high-pressure rapid preparation method of the AB-site high-entropy strontium titanate bulk thermoelectric material according to claim 2, characterized in that The SrO, CaO, BaO, La2O3, TiO2, Nb2O3, ZrO2, and HfO2 are added in the form of powders, and their purities are not less than 99.9%.

4. The high-pressure rapid preparation method of the AB-site high-entropy strontium titanate bulk thermoelectric material according to claim 1, characterized in that The green body is in a cylindrical shape.

5. The high-pressure rapid preparation method of the AB-site high-entropy strontium titanate bulk thermoelectric material according to claim 1, wherein The molecular formula of the ABO high-entropy strontium titanate bulk thermoelectric material is Sr 0.6 La 0.2 Ca 0.1 Ba 0.1 Ti 0.6 Nb 0.2 Zr 0.1 Hf 0. 1O3.

6. An ABO high-entropy strontium titanate bulk thermoelectric material prepared by the high-pressure rapid preparation method according to any one of claims 1-5.

7. An application of the ABO high-entropy strontium titanate bulk thermoelectric material according to claim 6 in the mutual conversion of thermal energy and electrical energy.

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