Near-room-temperature high-power-factor NbFeSb-based semi-Heusler thermoelectric material and preparation method and application thereof

Abstract

The invention provides a near-room-temperature NbFeSb-based semi-Heusler thermoelectric material with a high power factor and a preparation method and application thereof, the chemical composition of the near-room-temperature NbFeSb-based semi-Heusler thermoelectric material with the high power factor is Nb < 1-x > M < x > FeSb < 0.98 > Sn < 0.02 >, x is in a range of 0.05-0.3, x is in a range of 0.05-0.3, and y is in a range of 0.05-0.3. M is Ti, Zr and Hf, and the molar ratio of Ti to Zr to Hf is 1: 1: 1. According to the near-room-temperature NbFeSb-based semi-Heusler thermoelectric material with the high power factor, the high power factor is obtained by accurately controlling the carrier concentration, meanwhile, the lattice thermal conductivity is effectively inhibited, and a foundation is laid for high output power density of a device. The method has good application prospects and large-scale popularization potential in the fields of distributed low-grade waste heat recovery power generation and the like.

Description

Technical Field

[0001] This invention relates to thermoelectric materials technology, and more particularly to a near-room temperature high power factor NbFeSb-based semi-Hassler thermoelectric material, its preparation method and application. Background Technology

[0002] Thermoelectric materials, as a new type of clean energy material, can directly convert heat energy into electrical energy based on the Seebeck effect and the Peltier effect. They are considered one of the most competitive candidate materials for addressing global energy challenges. The performance of thermoelectric materials is usually expressed as the dimensionless thermoelectric figure of merit. ZT ( ZT = S ² σT / κ () is used as the core evaluation indicator. ZT The higher the power factor, the higher the thermoelectric conversion efficiency. Essentially, the realization of high-performance thermoelectric devices mainly relies on the synergistic optimization of the electroacoustic transport processes within the thermoelectric material. Among these, a high power factor (…) PF = S²σ The output power density of thermoelectric devices is one of the key factors that determine the output power density of thermoelectric devices.

[0003] Among numerous thermoelectric material systems, NbFeSb-based semi-Hassler alloys exhibit unique performance potential. This material possesses a large effective band mass and high band degeneracy, providing an ideal electronic structure basis for achieving high power factors through precise carrier concentration control. However, the relatively simple crystal structure of this alloy also results in high intrinsic lattice thermal conductivity, making heat easily dissipated through phonon conduction, thus severely limiting the actual power density of the device. Therefore, while introducing multi-scale defect phonon scattering to reduce lattice thermal conductivity, effectively optimizing the power factor becomes crucial for improving the material's performance. ZT The key issues that urgently need to be addressed are the value and the realization of high output power density of devices. Summary of the Invention

[0004] The purpose of this invention is to address the aforementioned problems by proposing a near-room-temperature high-power-factor NbFeSb-based semi-Hassler thermoelectric material. This thermoelectric material effectively improves the near-room-temperature power factor while reducing lattice thermal conductivity, laying the foundation for high output power density in devices. It has promising application prospects and large-scale promotion potential in fields such as distributed generation and low-grade waste heat recovery power generation.

[0005] It should be noted that, in this invention, unless otherwise specified, the specific meaning of "comprising" in relation to composition and description includes both open-ended meanings such as "comprising," "including," etc., and closed-ended meanings such as "composed of," "consisting of," etc., and similar meanings.

[0006] To achieve the above objectives, the technical solution adopted by this invention is: a near-room temperature high power factor NbFeSb-based semi-Hassler thermoelectric material, the chemical composition of which is: Nb 1-x M x FeSb 0.98 Sn 0.02 The value of x ranges from 0.05 to 0.3; M is Ti, Zr, and Hf.

[0007] Furthermore, the value of x ranges from 0.05 to 0.2.

[0008] Furthermore, the molar amounts of Ti, Zr, and Hf are the same, that is, the molar ratio of Ti, Zr, and Hf is 1:1:1.

[0009] This invention achieves dual modulation of electroacoustic transport in NbFeSb-based alloys by equimolar doping of Ti, Zr, and Hf at the Nb sites. While reducing lattice thermal conductivity, it effectively improves the near-room-temperature power factor, laying the foundation for high output power density in devices.

[0010] Furthermore, the power factor of the near-room temperature high power factor NbFeSb-based semi-Hassler thermoelectric material is 32.9 μW cm⁻¹. -1 K -2 ~58.7 μW cm -1 K -2 .

[0011] Furthermore, the lattice thermal conductivity of the near-room temperature high power factor NbFeSb-based semi-Hassler thermoelectric material is 2.16 W / m. -1 K -1 ~4.26 W m -1 K -1 .

[0012] Another objective of this invention discloses a method for preparing a near-room-temperature high-power-factor NbFeSb-based semi-Hassler thermoelectric material, comprising the following steps: Materials were weighed according to their chemical composition and placed in a magnetic levitation melting furnace for melting under a protective atmosphere. The resulting alloy ingots were then ball-milled in a planetary ball mill, followed by filtration and drying to obtain powder. The powder was then sintered using spark plasma sintering technology to obtain the near-room temperature high power factor NbFeSb-based semi-Hassler thermoelectric material.

[0013] Furthermore, the preparation method of NbFeSb-based semi-Hassler thermoelectric material with high power factor near room temperature includes the following steps: Step (1) Weigh Nb, Ti, Zr, Hf, Fe, Sb and Sn particles according to the chemical composition of the near-room temperature high power factor NbFeSb-based semi-Hassler thermoelectric material; Step (2) The raw materials are placed in a magnetic levitation melting furnace and melted under an argon atmosphere to obtain alloy ingots. The melting pressure is 10. 4 ~10 5 Pa, the smelting is divided into heating and holding stages; the heating rate of the heating and melting stage is 303~308K / s, and the heating time is based on the complete melting of the raw materials; the holding temperature of the holding stage is 2073~2273K, and the holding time is 30~60s. Step (3) Place the alloy ingot in a planetary ball mill for wet ball milling to obtain wet powder with a particle size of 0.5 to 2 μm; Step (4) Dry the wet powder; Step (5) The powder is sintered using discharge plasma sintering technology at a temperature of 1073–1273 K, a sintering pressure of 60–80 MPa, and a holding time of 5–20 minutes to obtain a near-room temperature high power factor NbFeSb-based semi-Hassler thermoelectric material.

[0014] Furthermore, in step (1), the Nb, Ti, Zr, Hf, Fe, Sb and Sn particles are particles with a diameter of 0.5 to 10 mm.

[0015] Furthermore, in step (1), the Nb, Ti, Zr, Hf, Fe, Sb and Sn particles are placed in a magnetic levitation melting furnace for melting in order of their melting points.

[0016] Furthermore, the melting process in step (2) is repeated 4 to 8 times to ensure the uniformity of the structure after melting.

[0017] Further, the wet ball milling in step (3) includes: first, crushing the alloy ingot with a tablet press, and then performing wet ball milling. The ball milling medium is anhydrous ethanol, the ball-to-material ratio is 15:1~20:1, the rotation speed is 300~700 r / min, and the ball milling time is 10~16 h.

[0018] Furthermore, in step (3), the preferred ball-to-material ratio for wet ball milling is 15:1 to 18:1, the preferred rotation speed is 400 to 600 r / min, and the preferred ball milling time is 12 to 14 h.

[0019] Furthermore, in step (3), the powder is obtained by wet ball milling followed by filtration and drying.

[0020] Further, the drying in step (4) includes: naturally drying the wet powder in a glove box for 12 to 48 hours.

[0021] Further, in step (5), the powder is sintered using discharge plasma sintering technology. The sintering temperature is preferably 1073~1123K, the sintering pressure is preferably 65~70MPa, and the holding time is preferably 10~15min.

[0022] Another objective of this invention is to disclose the application of a near-room temperature high power factor NbFeSb-based semi-Hassler thermoelectric material in distributed, low-grade waste heat recovery power generation and other fields.

[0023] Furthermore, the near-room temperature high power factor NbFeSb-based semi-Hassler thermoelectric material is particularly suitable for applications such as industrial waste heat and automotive exhaust waste heat.

[0024] The present invention relates to a near-room-temperature high-power-factor NbFeSb-based semi-Hassler thermoelectric material, its preparation method, and its applications, which have the following advantages compared with existing technologies: 1) The present invention relates to a near-room temperature high power factor NbFeSb-based semi-Hassler thermoelectric material. By doping the Nb site with Ti, Zr, and Hf in equal molar amounts, the thermoelectric performance of the NbFeSb-based semi-Hassler thermoelectric material is significantly improved. At 923 K, the ZT value reaches a maximum of 0.52, which expands the application range of the material and is expected to be widely used in industrial waste heat and automotive exhaust waste heat.

[0025] 2) The near-room temperature high power factor NbFeSb-based semi-Hassler thermoelectric material of this invention exhibits a high power factor, with a maximum power factor reaching 58.7 μW cm⁻¹. -1 K -2 It has a low lattice thermal conductivity, with a minimum lattice thermal conductivity of 2.16 W / m. -1 K -1 This has significant application value for achieving high output power density in devices.

[0026] 3) The preparation method of the near-room temperature high power factor NbFeSb-based semi-Hassler thermoelectric material of the present invention has the advantages of short process, few steps and easy control, and has the prospect of large-scale commercial production and application.

[0027] In summary, the near-room temperature high power factor NbFeSb-based semi-Hassler thermoelectric material of this invention has good application prospects and large-scale promotion potential in fields such as distributed, low-grade waste heat recovery power generation. Attached Figure Description

[0028] Figure 1 NbFeSb in Comparative Example 1 and Nb in Examples 1-4 1-x M x FeSb 0.98 Sn 0.02(M=Ti, Zr, Hf), Nb from Comparative Examples 2-4 1-y Ti y FeSb 0.98 Sn 0.02 XRD patterns of semi-Hassler thermoelectric materials; Figure 2 NbFeSb in Comparative Example 1 and Nb in Examples 1-4 1-x M x FeSb 0.98 Sn 0.02 (M=Ti, Zr, Hf), Nb from Comparative Examples 2-4 1-y Ti y FeSb 0.98 Sn 0.02 The electrical conductivity of the semi-Hassler thermoelectric material; Figure 3 NbFeSb in Comparative Example 1 and Nb in Examples 1-4 1-x M x FeSb 0.98 Sn 0.02 (M=Ti, Zr, Hf), Nb from Comparative Examples 2-4 1-y Ti y FeSb 0.98 Sn 0.02 The Seebeck coefficient of the semi-Hassler thermoelectric material; Figure 4 NbFeSb in Comparative Example 1 and Nb in Examples 1-4 1-x M x FeSb 0.98 Sn 0.02 (M=Ti, Zr, Hf), Nb from Comparative Examples 2-4 1-y Ti y FeSb 0.98 Sn 0.02 The power factor of the semi-Hassler thermoelectric material; Figure 5 NbFeSb in Comparative Example 1 and Nb in Examples 1-4 1-x M x FeSb 0.98 Sn 0.02 (M=Ti, Zr, Hf), Nb from Comparative Examples 2-4 1-y Ti y FeSb 0.98 Sn 0.02 The total thermal conductivity of the half-Hassler thermoelectric material; Figure 6 NbFeSb in Comparative Example 1 and Nb in Examples 1-4 1-x M x FeSb0.98 Sn 0.02 (M=Ti, Zr, Hf), Nb from Comparative Examples 2-4 1-y Ti y FeSb 0.98 Sn 0.02 The lattice thermal conductivity of the semi-Hassler thermoelectric material; Figure 7 NbFeSb in Comparative Example 1 and Nb in Examples 1-4 1-x M x FeSb 0.98 Sn 0.02 (M=Ti, Zr, Hf), Nb from Comparative Examples 2-4 1-y Ti y FeSb 0.98 Sn 0.02 The thermoelectric figure of merit of the semi-Hassler thermoelectric material. Detailed Implementation

[0029] The present invention will be further described below with reference to embodiments. The description of the technical features described below is based on representative embodiments and specific examples of the present invention, but the present invention is not limited to these embodiments and specific examples. It should be noted that: Unless otherwise stated, all units used in this specification are international standard units, and all numerical values ​​and ranges appearing in this invention should be understood to include systematic errors that are unavoidable in industrial production.

[0030] In this specification, the range of values ​​referred to as "value A to value B" refers to the range including the endpoint values ​​A and B.

[0031] In this specification, the numerical range indicated by "above" or "below" refers to the numerical range that includes the stated number.

[0032] In this specification, the word "may" has two meanings: to perform a certain process and not to perform a certain process.

[0033] In this specification, the terms "optional" or "optional" are used to indicate the use or omission of certain substances, components, procedures, application conditions, etc.

[0034] In this instruction manual, when "room temperature" or "room temperature" is used, the temperature can be 288~298K.

[0035] Unless otherwise specified, all reagents or instruments used in this instruction manual are commercially available products.

[0036] This invention provides a near-room temperature high power factor NbFeSb-based semi-Hassler thermoelectric material and its preparation method. The chemical composition of the thermoelectric material is: Nb 1-x M x FeSb 0.98 Sn 0.02 The value of x ranges from 0.05 to 0.3; M includes Ti, Zr, and Hf.

[0037] In this invention, the value of x in the near-room temperature high power factor NbFeSb-based semi-Hassler thermoelectric material is preferably in the range of 0.05 to 0.2, specifically 0.09, 0.12, 0.15 or 0.18.

[0038] This invention also provides a method for preparing the near-room temperature high power factor NbFeSb-based semi-Hassler thermoelectric material described above, comprising the following steps: (1) According to the chemical composition of the near-room temperature high power factor NbFeSb-based semi-Hassler thermoelectric material, the raw materials are smelted in a protective atmosphere to obtain an alloy ingot; (2) The alloy ingot is subjected to wet ball milling, drying and discharge plasma sintering in sequence to obtain the near room temperature high power factor NbFeSb-based semi-Hasler thermoelectric material.

[0039] According to the chemical composition of the near-room temperature high power factor NbFeSb-based semi-Hassler thermoelectric material, the raw materials are smelted in a protective argon atmosphere to obtain an alloy ingot. In this invention, the raw materials preferably include Nb particles, Ti particles, Zr particles, Hf particles, Fe particles, Sb particles, and Sn particles. This invention does not have any special limitations on the source of the Nb particles, Ti particles, Zr particles, Hf particles, Fe particles, Sb particles, and Sn particles; commercially available products well known to those skilled in the art can be used.

[0040] In specific embodiments of the present invention, the Nb particles are preferably metallic Nb with a purity of 99.95%; the Ti particles are preferably metallic Ti with a purity of 99.995%; the Zr particles are preferably metallic Zr with a purity of 99.95%; the Hf particles are preferably metallic Hf with a purity of 99.95%; the Fe particles are preferably metallic Fe with a purity of 99.95%; the Sb particles are preferably metallic Sb with a purity of 99.99%; and the Sn particles are preferably metallic Sn with a purity of 99.99%.

[0041] In a specific embodiment of the present invention, since Sb element volatilizes during the magnetic levitation vacuum melting process, a certain amount of Sb particles need to be added to make up for the loss. The actual amount of Sb particles added is 2% to 5% more than the mass of Sb particles weighed according to the molar ratio specified in the above technical solution.

[0042] In this invention, the smelting preferably includes magnetic levitation smelting; the smelting preferably includes a heating stage and a holding stage; the heating rate of the heating stage is preferably 303-308 K / s, specifically 303 K / s, 304 K / s, 305 K / s, 306 K / s, 307 K / s or 308 K / s, and the time is based on the complete melting of the raw materials; the temperature of the holding stage is preferably 2073-2273 K, specifically 2073 K, 2123 K, 2173 K, 2223 K or 2273 K, and the holding time is preferably 30-60 s, specifically 30 s, 40 s, 50 s or 60 s.

[0043] In this invention, the number of melting operations is preferably 4 or more, specifically 4, 5, 6, 7 or 8 times; the melting equipment is preferably a magnetic levitation melting furnace.

[0044] In this invention, the ball milling is preferably wet ball milling; the medium for wet ball milling is preferably anhydrous ethanol; and the grinding balls used in the ball milling are preferably tungsten carbide balls. In this invention, the sintering is preferably spark plasma sintering; the sintering temperature is preferably 1073~1273K, specifically 1073K, 1123K, 1173K, 1223K or 1273K; the pressure is preferably 60~80MPa, specifically 60MPa, 65MPa, 70MPa, 75MPa or 80MPa; the holding time is preferably 5~20min, specifically 5min, 10min, 15min or 20min; the sintering is preferably carried out in a graphite mold. This invention, through spark plasma sintering, can make the alloy interior more compact and reduce the porosity within the alloy.

[0045] To further illustrate the present invention, the following detailed description of the invention's solutions, in conjunction with the accompanying drawings and embodiments, is provided, but should not be construed as limiting the scope of protection of the present invention.

[0046] Example 1 This embodiment discloses a near-room temperature high power factor NbFeSb-based semi-Hassler thermoelectric material with a chemical composition of Nb. 0.91 M 0.09 FeSb 0.98 Sn 0.02Where M represents Ti, Zr, and Hf, and the molar ratio of Ti, Zr, and Hf is 1:1:1, this thermoelectric material can be abbreviated as Nb 0.91 M 0.09 FeSb 0.98 Sn 0.02 (M = Ti, Zr, Hf), and its preparation method is as follows: Raw material selection: Nb, Ti, Zr, Hf, Fe, Sb, and Sn are small particles with a diameter of 0.5–10 mm. The purity of all materials is ≥99.95%. Ingredients: According to Nb 0.91 M 0.09 FeSb 0.98 Sn 0.02 The ingredients are prepared according to the stoichiometric ratio of (M = Ti, Zr, Hf); Melting: The metals are placed in a magnetic levitation melting furnace in order of their melting points, under a protective argon atmosphere and at a pressure of 10. 5 Pa. Heat to 2173K and hold for 30 seconds, repeat the melting process 5 times to ensure uniform microstructure; Ball milling: First, the ingot is crushed using a tablet press, and then wet ball milling is performed. The ball milling medium is anhydrous ethanol, the ball-to-material ratio is 15:1, the rotation speed is 500 r / min, and the ball milling time is 12 h. After wet ball milling, the powder is obtained by filtration and drying.

[0047] Drying treatment: The filtered powder is naturally dried in a glove box for 48 hours.

[0048] Sintering: The dried powder was loaded into a graphite mold and sintered using spark plasma sintering technology at a temperature of 1123 K, a sintering pressure of 65 MPa, and a holding time of 10 min to obtain Nb. 0.91 M 0.09 FeSb 0.98 Sn 0.02 (M=Ti, Zr, Hf) thermoelectric materials.

[0049] Example 2 This embodiment discloses a near-room temperature high power factor NbFeSb-based semi-Hassler thermoelectric material with a chemical composition of Nb. 0.88 M 0.12 FeSb 0.98 Sn 0.02 (M = Ti, Zr, Hf); its preparation method is the same as in Example 1.

[0050] Example 3 This embodiment discloses a near-room temperature high power factor NbFeSb-based semi-Hassler thermoelectric material with a chemical composition of Nb. 0.85 M0.15 FeSb 0.98 Sn 0.02 (M = Ti, Zr, Hf); its preparation method is the same as in Example 1.

[0051] Example 4 This embodiment discloses a near-room temperature high power factor NbFeSb-based semi-Hassler thermoelectric material with a chemical composition of Nb. 0.82 M 0.18 FeSb 0.98 Sn 0.02 (M = Ti, Zr, Hf); its preparation method is the same as in Example 1.

[0052] Comparative Example 1 This comparative example discloses a thermoelectric material with the chemical composition NbFeSb; the preparation method is the same as in Example 1.

[0053] Comparative Example 2 This comparative example discloses a thermoelectric material with the chemical composition Nb 0.92 Ti 0.08 FeSb 0.98 Sn 0.02 The preparation method is the same as in Example 1.

[0054] Comparative Example 3 This comparative example discloses a thermoelectric material with the chemical composition Nb 0.88 Ti 0.12 FeSb 0.98 Sn 0.02 The preparation method is the same as in Example 1.

[0055] Comparative Example 4 This comparative example discloses a thermoelectric material with the chemical composition Nb 0.84 Ti 0.16 FeSb 0.98 Sn 0.02 The preparation method is the same as in Example 1.

[0056] The thermoelectric materials of Examples 1-4 and Comparative Examples 1-4 were tested respectively, and the test results are as follows: Test Example 1 XRD tests were performed on the semi-Hassler thermoelectric materials obtained in Examples 1-4 and Comparative Examples 1-4 using an X-ray diffractometer. The test results are as follows: Figure 1 As shown, from Figure 1 As can be seen, the diffraction peaks of all samples are consistent with the standard PDF card of NbFeSb, and no characteristic impurity peaks were detected, indicating that all samples are single phases with good symmetry.

[0057] Test Example 2 The electrical properties of the semi-Hassler thermoelectric materials obtained in Examples 1-4 and Comparative Examples 1-4 were tested using the LSR-3 electrical performance testing system. The conductivity test curves are shown below. Figure 2 As shown, the test curve for the Seebeck coefficient is as follows: Figure 3 As shown, the power factor test curve is as follows: Figure 4 As shown. From Figure 2 As can be seen from the example Nb 1-x M x FeSb 0.98 Sn 0.02 The conductivity (x=0.12~0.18) is significantly higher than that of Comparative Example 1 NbFeSb and Comparative Example 2-4 Nb 1-y Ti y FeSb 0.98 Sn 0.02 (y=0.08~0.12), Example Nb 0.85 M 0.15 FeSb 0.98 Sn 0.02 The maximum conductivity of 5096.84 S cm was obtained at room temperature. -1 ;from Figure 3 As can be seen from the example Nb 1-x M x FeSb 0.98 Sn 0.02 The Seebeck coefficient (x=0.12~0.18) is slightly lower than that of the comparative Nb. 1-y Ti y FeSb 0.98 Sn 0.02 (y=0.08~0.16), this is mainly related to the type of dopant element; from Figure 4 It can be seen that, considering the combined effects of conductivity and Seebeck coefficient, the Nb example... 0.91 M 0.09 FeSb 0.98 Sn 0.02 The maximum power factor of 58.7 μWcm was obtained at 373 K. -1 K -2 .

[0058] Test Example 3 Figure 5 and Figure 6 These are the total thermal conductivity and lattice thermal conductivity of the embodiment, respectively. From... Figure 5 and Figure 6 As can be seen from the example Nb 1-x M x FeSb 0.98 Sn 0.02The total thermal conductivity and lattice thermal conductivity of (x=0.12~0.18) are significantly lower than those of the comparative examples NbFeSb and Nb. 1-y Ti y FeSb 0.98 Sn 0.02 (y=0.08~0.16), which indicates that equimolar doping of Ti, Zr and Hf at the Nb site, compared with undoped NbFeSb and single-doped Ti at the Nb site, will cause stronger fluctuations in the mass field and stress field, effectively reduce the phonon mean free path, and ultimately significantly suppress its total thermal conductivity and lattice thermal conductivity.

[0059] Test Example 4 According to the formula ZT =( S 2 σ / κ tot ) T The thermoelectric figure of merit of the semi-Hassler thermoelectric materials obtained in Examples 1-4 and Comparative Examples 1-4 was calculated. ZT ,in S The Zebeck coefficient, T Absolute temperature κ tot Total thermal conductivity σ The results curves for electrical conductivity and thermoelectric figure of merit are shown below. Figure 7 As shown, in embodiment Nb 1-x M x FeSb 0.98 Sn 0.02 The thermoelectric figure of merit (x=0.09~0.18) is significantly higher than that of the comparative examples NbFeSb and Nb. 1-y Ti y FeSb 0.98 Sn 0.02 (y=0.08~0.12), at 923K, Nb 0.82 M 0.18 FeSb 0.98 Sn 0.02 Get the maximum ZT The value is 0.52. Furthermore, in example Nb... 1-x M x FeSb 0.98 Sn 0.02 The average thermoelectric figure of merit (x=0.09~0.18) all exceeded 0.33, with the maximum average thermoelectric figure of merit being 0.37, which is higher than that of the comparative examples NbFeSb and Nb. 1-y Ti y FeSb 0.98 Sn 0.02The average thermoelectric figure of merit (y=0.08~0.16) is mainly derived from the example Nb 1-x M x FeSb 0.98 Sn 0.02 (x=0.09~0.18) Excellent thermoelectric performance across the entire temperature range. This is crucial for expanding the application boundaries of NbFeSb thermoelectric materials and improving the overall efficiency of devices.

[0060] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A near room temperature high power factor NbFeSb-based half-Heusler thermoelectric material, characterized in that, The chemical composition is: Nb 1-x M x FeSb 0.98 Sn 0.02 Wherein, the value range of x is 0.05~0.3; the M is Ti, Zr and Hf.

2. The near room temperature high power factor NbFeSb-based half-Heusler thermoelectric material of claim 1, wherein, The molar ratio of Ti, Zr and Hf is 1:1:

1.

3. A method of producing a near room temperature high power factor NbFeSb-based semi-Heusler thermoelectric material according to claim 1 or 2, characterized in that, The method comprises the following steps: The materials are weighed according to the chemical composition and placed in a magnetic levitation smelting furnace for smelting in a protective atmosphere, the alloy ingot obtained by smelting is placed in a planetary ball mill for ball milling, and then filtration and drying are performed to obtain a powder, and the powder is sintered by using a spark plasma sintering technology to obtain the near-room-temperature high-power-factor NbFeSb-based half-Heusler thermoelectric material.

4. The method of claim 3, wherein the NbFeSb-based semi-Heusler thermoelectric material has a high power factor near room temperature. The method comprises the following steps: Step (1) weighing Nb, Ti, Zr, Hf, Fe, Sb and Sn particles according to the chemical composition of the near-room-temperature high-power-factor NbFeSb-based half-Heusler thermoelectric material; Step (2) Put the raw material into a magnetic levitation melting furnace, and melt to obtain an alloy ingot under an argon atmosphere, wherein the melting pressure is 10 4 ~10 5 Pa, and the melting is divided into a heating stage and a holding stage; the heating rate of the heating melting stage is 303~308 K / s, and the heating time is based on the complete melting of the raw material; the holding temperature of the holding stage is 2073~2273 K, and the holding time is 30~60 s; Step (3) wet ball milling the alloy ingot in a planetary ball mill to obtain a wet powder; Step (4) drying the wet powder; Step (5) sintering the powder by using a spark plasma sintering technology, the sintering temperature is 1073-1273K, the sintering pressure is 60-80MPa, and the holding time is 5-20 minutes, to obtain the near-room-temperature high-power-factor NbFeSb-based half-Heusler thermoelectric material.

5. The method of claim 3, wherein the NbFeSb-based semi-Heusler thermoelectric material has a high power factor near room temperature. In step (1), the Nb, Ti, Zr, Hf, Fe, Sb and Sn particles are particles with a diameter of 0.5-10mm.

6. The method of claim 3, wherein the NbFeSb-based semi-Heusler thermoelectric material has a high power factor near room temperature. In step (1), the Nb, Ti, Zr, Hf, Fe, Sb and Sn particles are sequentially placed in a magnetic levitation smelting furnace for smelting according to the melting points.

7. The method of claim 3, wherein the NbFeSb-based semi-Heusler thermoelectric material has a high power factor near room temperature. In step (2), the smelting is performed for 4-8 times.

8. The method of claim 3, wherein the NbFeSb-based semi-Heusler thermoelectric material has a high power factor near room temperature. In step (3), the wet ball milling comprises: firstly crushing the alloy ingot by using a tablet press, and then performing wet ball milling, the ball milling medium is anhydrous ethanol, the ball-to-material ratio is 15:1-20:1, the rotating speed is 300-700r / min, and the ball milling time is 10-16h.

9. The method of claim 3, wherein the NbFeSb-based semi-Heusler thermoelectric material has a high power factor near room temperature. In step (4), the drying comprises: naturally drying the wet powder in a glove box for 12-48h.

10. Application of the near-room-temperature high-power-factor NbFeSb-based half-Heusler thermoelectric material in the field of distributed, low-grade waste heat recovery power generation, etc.

Images