A half-heusler structure thermoelectric material, and a preparation method and application thereof

Abstract

The application belongs to the technical field of thermoelectric materials, and particularly relates to a half-Heusler structure thermoelectric material and a preparation method and application thereof. The thermoelectric material is an N-type thermoelectric material formed by substituting Ru in NbRuSb with Ni element, and has a chemical formula of NbRu 1‑x Ni x Sb, wherein x is in a range of 0 < x <= 0.1; the half-Heusler structure thermoelectric material is prepared by using Nb element, Ru element, Ni element and Sb element as raw materials and by adopting high-energy ball milling, spark plasma sintering and annealing methods; and the material can be applied to thermoelectric device manufacturing. Compared with the prior art, the thermoelectric material prepared by the application optimizes the thermoelectric performance of the half-Heusler structure thermoelectric material, wherein NbRu 0.9 Ni 0.1 Sb has the highest thermoelectric performance, the power factor is as high as 34.8 muW·cm ‑1 ·K ‑2 at 682K, and zT is 0.404 at 982K.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of thermoelectric materials, and particularly relates to a semi-Heusler structure thermoelectric material and a preparation method and application thereof. BACKGROUND

[0002] Energy, material and information are three pillars of human society development. Modern human civilization society developed since the industrial revolution is largely relying on fossil fuel energy such as coal, oil and natural gas. However, these energies are not inexhaustible, and the more developed the society is, the more energy is needed, and the non-renewable fossil fuels are facing a storage crisis. In the face of the depletion of fossil fuels, in addition to advocating the use of renewable clean energy such as solar energy, wind energy and water power, the development of clean and reliable energy conversion technology has attracted widespread attention. Modern industry is a very energy-consuming industry, and there is also a large amount of energy waste. As a kind of energy conversion material, thermoelectric materials can be effectively used in the recycling of industrial waste heat, automobile engine and exhaust waste heat, and have great significance for improving energy use efficiency and alleviating energy crisis. In addition, household heating and refrigeration appliances also have the application of thermoelectric devices, and it can be said that from the sustainable development of society to the convenience of daily life, thermoelectric materials can make contributions.

[0003] Thermoelectric materials realize the direct reversible conversion between heat and electricity, and the conversion process includes three effects: the Seebeck effect, the Peltier effect and the Thomson effect. The three provide a theoretical basis for systematic study of thermoelectric materials. Thermoelectric devices have the characteristics of simple structure, no moving parts, precise temperature control, both cold and hot, and no gas-liquid working medium. Thermoelectric materials include a large number of material systems, and materials with excellent thermoelectric performance and thermal stability can be found to match different temperature application scenarios. The size of the dimensionless thermoelectric merit value zT measures the energy conversion efficiency of thermoelectric materials, zT=S 2 σT / κ, where S, σ, κ, T are the Seebeck coefficient, electrical conductivity, thermal conductivity and absolute temperature of the environment, respectively.

[0004] Semi-Heusler alloy is a kind of medium-high temperature thermoelectric material, which has excellent mechanical properties and thermal stability at high temperature, and its chemical formula can be written as ABX. The research on this kind of thermoelectric material can be distinguished by the number of valence electrons. SUMMARY

[0005] The present application aims to solve at least one of the above problems, and provides a half-Heusler structure thermoelectric material, a preparation method thereof and an application thereof.

[0006] The present application aims to solve at least one of the above problems, and provides a half-Heusler structure thermoelectric material, a preparation method thereof and an application thereof.

[0007] One of the technical solutions of the present application is to provide a half-Heusler structure thermoelectric material, which is an N-type thermoelectric material formed by replacing Ru in NbRuSb, and has a chemical formula of NbRu 1-x Ni x Sb, wherein x is in a range of 0 < x < 0.1.

[0008] Further, in the NbRu 1-x Ni x Sb, the value of x is selected from any one of 0.02, 0.04, 0.06, 0.08 and 0.1.

[0009] Further, the electrical conductivity of the thermoelectric material is in a range of 1770-80700 S·m -1 , the Seebeck coefficient is in a range of (-340)-(-160) μV·K -1 , the power factor is in a range of 1.1-34.9 μW·cm -1 ·K -2 , the thermal conductivity is in a range of 5.72-11.91 W·m -1 ·K -1 , and the zT value is in a range of 0.003-0.404.

[0010] Further, when the value of x is 0.1, the NbRu 0.9 Ni 0.1 Sb has a highest power factor of 23 μW·cm -1 ·K -2 at a temperature of 682 K.

[0011] The second technical solution of the present application is to provide a preparation method of the half-Heusler structure thermoelectric material as described above, which uses Nb, Ru, Ni and Sb as raw materials, and adopts high-energy ball milling, spark plasma sintering and annealing to prepare the half-Heusler structure thermoelectric material.

[0012] Further, the preparation method comprises the following steps:

[0013] S1: sample preparation: according to the stoichiometric ratio of Nb: Ru: Ni: Sb = 1: (1-x): x: 1, the Nb element, Ru element, Ni element and Sb element are weighed, wherein x is in the range of 0 < x ≤ 0.1;

[0014] S2: alloying: the weighed elements in step S1 are high-energy ball milled;

[0015] S3: sintering: the mixed powder obtained by high-energy ball milling in step S2 is spark plasma sintered;

[0016] S4: vacuum sealing: the material obtained by sintering in step S3 is vacuum sealed;

[0017] S5: annealing: the tube after vacuum sealing in step S4 is high-temperature annealed, and the semi-Hoogevelter thermoelectric material is obtained after cooling.

[0018] Further, the total amount of raw materials in step S1 is 0.02 mol, and the mass required by each element can be calculated by the formula m = n × M (n: the required moles of a certain element under a certain composition, m: the required mass, M: the atomic molar mass) and the stoichiometric ratio of the corresponding composition.

[0019] Further, in step S1, the Nb element, Ru element, Ni element and Sb element are Nb element, Ru powder, Ni element and Sb particle respectively.

[0020] Further, in step S1, the weighed elements are placed in a stainless steel ball mill tank in an inert gas environment.

[0021] Further, in step S2, the high-energy ball milling time is 20-24h.

[0022] Further, in step S2, the elements are continuously collided in the high-energy ball mill for a long time to obtain mixed powder.

[0023] Further, the sample in steps S1 and S2 and the mixed powder obtained by ball milling are stored in an inert gas environment.

[0024] Further, the inert gas is argon.

[0025] Further, in step S3, the spark plasma sintering includes the following steps: the mixed powder obtained by ball milling is placed in a graphite mold and vacuumized, then a pressure of 3.5-4kN is applied to the powder through the graphite mold, then sintering starts, the sintering gas pressure is 50-60MPa, the temperature is raised to 850℃ at a heating rate of 30-50℃ / min, then the temperature is kept for 10-15min, then the applied pressure is removed and naturally cooled to room temperature to obtain a bulk material.

[0026] Further, in step S4, the vacuum sealing process includes: placing the sintered material into a quartz tube, connecting the quartz tube with a sealing device, sealing the quartz tube by using the sealing device, performing 3-5 times of air extraction and air filling circulation, washing air, and vacuumizing to less than 3Pa, and performing high-temperature hydrogen-oxygen flame heating at the quartz plug to soften the quartz tube and vacuum seal the material.

[0027] Further, in step S5, the quartz tube is placed into a muffle furnace for annealing.

[0028] Further, in step S5, the annealing temperature of the high-temperature annealing is 800-850K, the heating rate is 1-2℃ / min, and the furnace is cooled after holding for 3-7 days.

[0029] The third technical scheme of the present application provides an application of the half-Heusler structure thermoelectric material in the manufacture of thermoelectric devices.

[0030] The present application first prepares a pure phase of the 18-valence-electron half-Heusler structure thermoelectric material NbRuSb, tests the intrinsic thermoelectric performance, and finds that the intrinsic NbRuSb exhibits N-type conduction type and has the characteristics of low electrical conductivity, high Seebeck coefficient and high thermal conductivity. The half-Heusler structure with 18 valence electrons can mostly be stably synthesized, the bonding state and antibonding state are separated to exhibit the physical properties of a semiconductor, and the characteristics of high power factor and high thermal conductivity are exhibited. In order to improve the problem of low carrier concentration of the intrinsic NbRuSb, the present application adopts the mode of substituting and doping Ru with Ni with more valence electrons to adjust the carrier concentration, aiming to invent a half-Heusler structure thermoelectric material with high thermoelectric performance, especially high power factor.

[0031] On the basis of the common knowledge in the art, the above-mentioned preferred conditions can be combined at will, i.e., the preferred embodiments of the present application are obtained.

[0032] Compared with the prior art, the present application has the following advantages:

[0033] 1. The new half-Heusler structure thermoelectric material prepared by the present application is an N-type thermoelectric material of NbRuSb and Ni elemental doping, and the chemical formula is NbRu 1-x Ni x Sb. By substituting and doping Ni elements at the lattice sites originally occupied by Ru, the thermoelectric performance of the new half-Heusler structure thermoelectric material is optimized, wherein NbRu 0.9 Ni 0.1 Sb has the highest thermoelectric performance, the power factor is as high as 34.8μW·cm -1 ·K -2 at 682K, and the zT is 0.404 at 982K.

[0034] 2, The process for preparing the new half-Heusler structure thermoelectric material includes the methods of high-energy ball milling (HEBM), spark plasma sintering (SPS) and annealing, and a pure phase in a half-Heusler structure is prepared, the prepared material has less impurities than other methods, and the process flow is short, simple to operate and easy to realize.

[0035] 3, The electrical conductivity of the new half-Heusler structure thermoelectric material compound prepared by the application shows different change rules with the increase of carrier concentration, which indicates the effectiveness of substitutional doping as an optimization strategy for thermoelectric performance.

[0036] 4, The new half-Heusler structure thermoelectric material prepared by the application optimizes the thermoelectric performance of the material, obtains a higher power factor, and provides a promising way for further reducing the thermal conductivity of the material and improving the zT value. BRIEF DESCRIPTION OF DRAWINGS

[0037] Figure 1 The X-ray diffraction pattern of the NbRuSb-based thermoelectric material in the embodiment 1-6 of the application. 1-x Ni x The structure formula schematic diagram of the Sb-based thermoelectric material.

[0038] Figure 2 The X-ray diffraction pattern of the NbRuSb-based thermoelectric material in the embodiment 1-6 of the application. 1-x Ni x The X-ray diffraction pattern of the Sb-based thermoelectric material.

[0039] Figure 3 The X-ray diffraction pattern of the NbRuSb-based thermoelectric material in the embodiment 1-6 of the application.

[0040] Figure 4 The electrical conductivity-temperature change curve schematic diagram of the NbRuSb-based thermoelectric material in the embodiment 1-6 of the application. 1-x Ni x The electrical conductivity-temperature change curve schematic diagram of the Sb-based thermoelectric material.

[0041] Figure 5 The carrier concentration at room temperature schematic diagram of the NbRuSb-based thermoelectric material in the embodiment 1-6 of the application. 1-x Ni x The carrier concentration at room temperature schematic diagram of the Sb-based thermoelectric material.

[0042] Figure 6 The Seebeck coefficient-temperature change curve schematic diagram of the NbRuSb-based thermoelectric material in the embodiment 1-6 of the application. 1-x Ni x The Seebeck coefficient-temperature change curve schematic diagram of the Sb-based thermoelectric material.

[0043] Figure 7 The Seebeck coefficient-temperature change curve schematic diagram of the NbRuSb-based thermoelectric material in the embodiment 1-6 of the application. 1-x Ni xSchematic diagram of temperature dependence of power factor of Sb-based thermoelectric material.

[0044] Figure 8 NbRuSb of the present application in Examples 1-6 1-x Ni x Schematic diagram of temperature dependence of thermal conductivity of Sb-based thermoelectric material.

[0045] Figure 9 NbRuSb of the present application in Examples 1-6 1-x Ni x Schematic diagram of temperature dependence of zT value of Sb-based thermoelectric material. DETAILED DESCRIPTION

[0046] The present application will be described in detail below with reference to the drawings and specific examples. The present embodiment is implemented on the premise of the technical solution of the present application, and gives detailed implementation and specific operation process, but the protection scope of the present application is not limited to the following examples.

[0047] Unless otherwise specified, the experimental reagents and raw materials used in the present application are commercially available.

[0048] The experimental methods in the following examples without specific conditions are selected according to conventional methods and conditions, or according to the instructions of the goods. Unless otherwise specified, the experimental instruments used in the present application are conventional laboratory experimental instruments.

[0049] Example 1

[0050] The present embodiment provides a half-Heusler structure thermoelectric material, specifically a N-type thermoelectric material based on NbRuSb and Ni elemental doping, with a chemical formula of NbRuSb.

[0051] In addition, the present embodiment also provides a preparation method of the half-Heusler structure thermoelectric material NbRuSb, which is synthesized by high-energy ball milling (HEBM), spark plasma sintering (SPS) and annealing method, and the specific steps are as follows:

[0052] S1: Calculation: according to the stoichiometric ratio of Nb: Ru: Ni: Sb = 1: 1: 0: 1 and the formula m = n x M, the mass of each element required for 0.02 mol NbRuSb is calculated;

[0053] S2: Sample preparation: in an argon glove box, the Nb sheet with a purity of 99.95%, the Ru powder with a purity of 99.95% and the Sb particles with a purity of 99.999% are weighed on an electronic balance with an accuracy of 0.1 mg according to the mass calculated in step S1, and the weighed raw materials are placed in a stainless steel ball mill jar;

[0054] S3: Alloying: The ball mill jar from step S2 is placed in a high-energy ball mill, and mixed powder is obtained by continuous and uninterrupted collision of balls and materials for 20 hours.

[0055] S4: Sintering: The mixed powder obtained in step S3 is stored in an argon glove box, and 0.8-1.0g of powder is weighed and placed in a graphite mold with a diameter of 10mm. Then, the mold is placed in a spark plasma sintering device and a vacuum is drawn. Then, the pressure is slowly applied to the sample to 50MPa to start sintering. The sintering rate is 20-30℃ / min and reaches 850℃ in 30min. Finally, after holding at this temperature for 10-15min, the pressure is released and the sample is allowed to cool naturally to room temperature to obtain a bulk material with a diameter of 10mm and a thickness of 0.9-1.5mm.

[0056] S5: Vacuum sealing: The sintered bulk material is placed into a quartz tube, and then vacuum sealing is performed. The specific process is to connect the quartz tube to the sealing equipment, seal the quartz tube with the sealing equipment, evacuate and fill the air 5 times, wash the air, evacuate to less than 3Pa, and use a high-temperature hydrogen-oxygen flame to strongly heat the quartz plug, soften the quartz tube and vacuum seal the bulk material.

[0057] S6: Annealing: The vacuum-sealed quartz tube is placed in a muffle furnace for annealing at a temperature of 850℃, a heating rate of 2℃ / min, and held for 3 days. Then the tube is furnace cooled to obtain the NbRuSb test material.

[0058] Example 2

[0059] This embodiment provides a semi-Hessler thermoelectric material, specifically an N-type thermoelectric material based on NbRuSb and Ni elemental doping, with the chemical formula NbRu 0.98 Ni 0.02 Sb, its structural formula is as follows Figure 1 As shown.

[0060] Furthermore, this embodiment also provides a semi-Hessler thermoelectric material NbRu. 0.98 Ni 0.02 The preparation method of Sb involves high-energy ball milling (HEBM), spark plasma sintering (SPS), and annealing. The specific steps are as follows:

[0061] S1: Calculation: Based on the stoichiometric ratio of Nb:Ru:Ni:Sb = 1:0.98:0.02:1 and the formula m = n × M, calculate 0.02 mol NbRu 0.98 Ni 0.02 The required mass of each element for Sb;

[0062] S2: Sample preparation: In an argon glove box, weigh the Nb flakes with a purity of 99.95%, Ru powder with a purity of 99.95%, Ni flakes with a purity of 99.95%, and Sb particles with a purity of 99.999% using an electronic balance with an accuracy of 0.1 mg, according to the mass calculated in step S1, and place the weighed raw materials into a stainless steel ball mill jar;

[0063] S3: Alloying: The ball mill jar from step S2 is placed in a high-energy ball mill, and mixed powder is obtained by continuous and uninterrupted collision of balls and materials for 20 hours.

[0064] S4: Sintering: The mixed powder obtained in step S3 is stored in an argon glove box, and 0.8-1.0g of powder is weighed and placed in a graphite mold with a diameter of 10mm. Then, the mold is placed in a spark plasma sintering device and a vacuum is drawn. Then, the pressure is slowly applied to the sample to 50MPa to start sintering. The sintering rate is 20-30℃ / min and reaches 850℃ in 30min. Finally, after holding at this temperature for 10-15min, the pressure is released and the sample is allowed to cool naturally to room temperature to obtain a bulk material with a diameter of 10mm and a thickness of 0.9-1.5mm.

[0065] S5: Vacuum sealing: The sintered bulk material is placed into a quartz tube, and then vacuum sealing is performed. The specific process is to connect the quartz tube to the sealing equipment, seal the quartz tube with the sealing equipment, evacuate and fill the air 5 times, wash the air, evacuate to less than 3Pa, and use a high-temperature hydrogen-oxygen flame to strongly heat the quartz plug, soften the quartz tube and vacuum seal the bulk material.

[0066] S6: Annealing: The vacuum-sealed quartz tube is placed in a muffle furnace for annealing at a temperature of 850℃, a heating rate of 2℃ / min, and held for 3 days. Then the tube is furnace cooled to obtain the NbRuSb test material.

[0067] Example 3

[0068] This embodiment is basically the same as the aforementioned Embodiment 2, except that:

[0069] This embodiment provides a semi-Hessler thermoelectric material, specifically an N-type thermoelectric material based on NbRuSb and Ni elemental doping, with the chemical formula NbRu 0.96 Ni 0.04 Sb.

[0070] Furthermore, this embodiment also provides a semi-Hessler thermoelectric material NbRu. 0.96 Ni 0.04The preparation method of Sb is to synthesize it by high-energy ball milling (HEBM), spark plasma sintering (SPS) and annealing. Except for the Nb:Ru:Ni:Sb = 1:0.96:0.04:1 in step S1, the other steps are the same as in Example 2.

[0071] Example 4

[0072] This embodiment is basically the same as the aforementioned Embodiment 2, except that:

[0073] This embodiment provides a semi-Hessler thermoelectric material, specifically an N-type thermoelectric material based on NbRuSb and Ni elemental doping, with the chemical formula NbRu 0.94 Ni 0.06 Sb.

[0074] Furthermore, this embodiment also provides a semi-Hessler thermoelectric material NbRu. 0.94 Ni 0.06 The preparation method of Sb is to synthesize it by high-energy ball milling (HEBM), spark plasma sintering (SPS) and annealing. Except for the Nb:Ru:Ni:Sb = 1:0.94:0.06:1 in step S1, the other steps are the same as in Example 2.

[0075] Example 5

[0076] This embodiment is basically the same as the aforementioned Embodiment 2, except that:

[0077] This embodiment provides a semi-Hessler thermoelectric material, specifically an N-type thermoelectric material based on NbRuSb and Ni elemental doping, with the chemical formula NbRu 0.92 Ni 0.08 Sb.

[0078] Furthermore, this embodiment also provides a semi-Hessler thermoelectric material NbRu. 0.98 Ni 0.02 The preparation method of Sb is to synthesize it by high-energy ball milling (HEBM), spark plasma sintering (SPS) and annealing. Except for the Nb:Ru:Ni:Sb = 1:0.92:0.08:1 in step S1, the other steps are the same as in Example 2.

[0079] Example 6

[0080] This embodiment is basically the same as the aforementioned Embodiment 2, except that:

[0081] This embodiment provides a semi-Hessler thermoelectric material, specifically an N-type thermoelectric material based on NbRuSb and Ni elemental doping, with the chemical formula NbRu 0.9 Ni0.1 Sb.

[0082] Furthermore, this embodiment also provides a semi-Hessler thermoelectric material NbRu. 0.9 Ni 0.1 The preparation method of Sb is to synthesize it by high-energy ball milling (HEBM), spark plasma sintering (SPS) and annealing. Except for the Nb:Ru:Ni:Sb = 1:0.9:0.1:1 in step S1, the other steps are the same as in Example 2.

[0083] Comparative Example 1

[0084] This comparative example is a thermoelectric material prepared by conventional methods in the prior art, with the chemical formula NbRuSb. The specific preparation method can be found in the paper "Ternary transition metal antimonides and bismuthides with MgAgAs-type and filled NiAs-type structure, 1996".

[0085] The elemental ratios of Examples 1-6 and Comparative Example 1 are shown in Table 1:

[0086] Table 1. Proportions of elements in the thermoelectric materials of Examples 1-6 and Comparative Example 1

[0087] Nb Ru Ni Sb Example 1 1 1 0 1 Example 2 1 0.98 0.02 1 Example 3 1 0.96 0.04 1 Example 4 1 0.94 0.06 1 Example 5 1 0.92 0.08 1 Example 6 1 0.9 0.1 1 Comparative Example 1 1 1 0 1

[0088] Subsequently, tests and analyses were conducted on Examples 1-6 and Comparative Example 1:

[0089] (1) The X-ray diffraction patterns of the thermoelectric materials obtained in Examples 1-6 and Comparative Example 1 were obtained by measuring the X-ray diffraction patterns on a Rigaku SmartLab-II diffractometer. The X-ray source used for the test was Cu-K. α Furthermore, the test sample was in powder form, and the results were as follows: Figure 2 As shown.

[0090] (2) The thermoelectric materials obtained in Examples 1 to 6 were tested for electrical properties using the ULVAC-RIKO ZEM-3 equipment. The test data included electrical conductivity and Seebeck coefficient.

[0091] (3) The thermoelectric materials obtained in Examples 1 to 6 were tested for thermal properties on a NETZSCH LFA 457 device, mainly testing the thermal diffusivity D.

[0092] The formula for calculating thermal conductivity is κ = DC. p ρ, where C p ρ is the heat capacity of the material, which can be estimated using the Dulong-Petty law, while ρ is the density of the material, which can be estimated using Archimedes' method of displacement.

[0093] (4) The thermoelectric materials obtained in Examples 1 to 6 were tested for room temperature carrier concentration using a physical property measurement system (PPMS).

[0094] Figure 2 and Figure 3 NbRu in Examples 1-6 of the present invention 1-x Ni x X-ray diffraction patterns of Sb-based thermoelectric materials and NbRuSb thermoelectric materials in Comparative Example 1. Figures 2-3 It can be seen that the NbRu prepared in this invention 1-x Ni x Sb-based thermoelectric materials have fewer impurity phases. Comparing the images of NbRuSb in Comparative Example 1 and Example 1, it was found that the material prepared by the present invention has fewer impurity phase peaks.

[0095] Figures 4-9 The graph shows the test results of the thermoelectric properties of the thermoelectric materials obtained in Examples 1-6.

[0096] Depend on Figure 4 It can be seen that the conductivity of all tested samples increases with the increase of Ni doping amount. For samples with x = 0, 0.02, and 0.04, the conductivity increases with the increase of temperature, showing the typical change characteristics of semiconductors. For samples with x = 0.06, 0.08, and 0.1, the conductivity shows a completely different change law of first increasing and then decreasing with the increase of temperature.

[0097] Depend on Figure 5 It can be seen that the carrier concentration of all samples increases with the increase of Ni doping amount.

[0098] Depend on Figure 6 It can be seen that the Seebeck coefficients of the test samples in Examples 1-6 are all negative, that is, Examples 1-6 are all N-type conductors dominated by electrons. The absolute value of the Seebeck coefficient decreases with the increase of Ni doping amount, and first decreases and then increases with the increase of temperature.

[0099] Depend on Figure 7 It can be seen that the power factor of all samples increases with the increase of Ni doping amount, and first increases and then decreases with the increase of temperature.

[0100] Depend on Figure 8 It can be seen that the thermal conductivity of all samples decreases monotonically with temperature. The thermal conductivity of samples with x = 0.02 and 0.04 is slightly lower than that of NbRuSb with x = 0. The thermal conductivity of samples with x = 0.06, 0.08, and 0.1 is equal to or even slightly higher than that of NbRuSb with x = 0. This is because the significant increase in carrier concentration leads to an increase in the contribution of electrons to thermal conductivity.

[0101] Depend on Figure 9 It can be seen that the thermoelectric figure of merit zT of all samples increases with the increase of Ni doping amount.

[0102] Based on the test results, it can be seen that the thermoelectric performance gradually increases with the increase of Ni doping content, among which NbRu 0.9 Ni 0.1 Compounds containing Sb exhibit the best performance: electrical conductivity in the range of 50,000–81,000 S·m. -1 Between; Seebeck coefficient is between (-240) and (-165) μV·K -1 Between; power factor between 21-35 μW·cm -1 ·K -2 Between; thermal conductivity between 6.14 and 11.91 W·m -1 ·K -1 The zT value is between 0.06 and 0.40. Thanks to the overall large power factor, the thermoelectric properties of the material are significantly improved.

[0103] In summary, this invention utilizes high-energy ball milling, spark plasma sintering, and annealing to efficiently synthesize NbRu. 1-x Ni x Sb(x=0, 0.02, 0.04, 0.06, 0.08, 0.1) is a pure phase of a semi-Hessler structure thermoelectric material, and these thermoelectric materials have a high power factor, with the composition being NbRu. 0.9 Ni 0.1 The Sb sample exhibits the highest thermoelectric performance, with a maximum power factor of 34.8 μW·cm at 682 K. -1 ·K -2 At 982K, the highest zT is 0.404.

[0104] The above description of the embodiments is provided to enable those skilled in the art to understand and use the invention. It will be apparent to those skilled in the art that various modifications can be made to these embodiments, and the general principles described herein can be applied to other embodiments without inventive effort. Therefore, the present invention is not limited to the above embodiments, and any improvements and modifications made by those skilled in the art based on the disclosure of the present invention without departing from the scope of the invention should be within the protection scope of the present invention.

Claims

1. A semi-Hessler structure thermoelectric material, characterized in that, The thermoelectric material is an N-type thermoelectric material formed by doping Ni with Ru to replace Ru in NbRuSb, and its chemical formula is NbRu 1-x Ni x Sb, where x takes values ​​ranging from 0 to 1. <x≤0.1。 2. The semi-Hessler structure thermoelectric material according to claim 1, characterized in that, The NbRu 1-x Ni x In Sb, the value of x is selected from any one of 0.02, 0.04, 0.06, 0.08, and 0.

1.

3. The semi-Hessler structure thermoelectric material according to claim 1, characterized in that, The electrical conductivity of the thermoelectric material is between 1770 and 80700 S·m. -1 The Seebeck coefficient is between (-340) and (-160) μV·K. -1 The power factor ranges from 1.1 to 34.9 μW·cm. -1 ·K -2 The thermal conductivity ranges from 5.72 to 11.91 W·m. -1 ·K -1 The zT value is between 0.003 and 0.404, and the above numerical range does not include the lower limit value.

4. A method for preparing a semi-Hessler structure thermoelectric material as described in claim 1, characterized in that, Semi-Hessler thermoelectric materials were prepared using Nb, Ru, Ni, and Sb as raw materials through high-energy ball milling, spark plasma sintering, and annealing.

5. The method for preparing a semi-Hessler structure thermoelectric material according to claim 4, characterized in that, The preparation method includes the following steps: S1: Sample preparation: Based on the stoichiometric ratio of Nb:Ru:Ni:Sb = 1:(1-x):x:1, weigh the elemental Nb, Ru, Ni, and Sb, where x takes values ​​ranging from 0 to 1. <x≤0.1; S2: Alloying: Mill the weighed elemental high-energy ball in step S1; S3: Sintering: The mixed powder obtained by high-energy ball milling in step S2 is subjected to spark plasma sintering; S4: Vacuum sealing: Vacuum sealing is performed on the material obtained by sintering in step S3; S5: Annealing: The tube after vacuum sealing in step S4 is subjected to high-temperature annealing and cooled to obtain the semi-Hessler thermoelectric material.

6. The method for preparing a semi-Hessler structure thermoelectric material according to claim 5, characterized in that, In step S2, the high-energy ball milling time is 20-24 hours.

7. The method for preparing a semi-Hessler structure thermoelectric material according to claim 5, characterized in that, The samples in steps S1 and S2, as well as the mixed powder obtained from ball milling, were stored in an inert gas environment.

8. The method for preparing a semi-Hessler structure thermoelectric material according to claim 5, characterized in that, In step S3, the spark plasma sintering includes the following steps: the mixed powder obtained by ball milling is placed in a graphite mold and vacuumed. Then, a pressure of 3.5-4 kN is applied to the powder through the graphite mold, and then sintering begins. The sintering pressure is 50-60 MPa. The temperature is raised to 850°C at a heating rate of 30-50°C / min, and then held for 10-15 min. After that, the applied pressure is removed and the material is allowed to cool naturally to room temperature to obtain a bulk material.

9. The method for preparing a semi-Hessler structure thermoelectric material according to claim 5, characterized in that, In step S5, the annealing temperature for high-temperature annealing is 800-850K, the heating rate is 1-2℃ / min, and the furnace is cooled after holding at that temperature for 3-7 days.

10. The application of a semi-Hessler structure thermoelectric material as described in claim 1 in the manufacture of thermoelectric devices.

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