Indium antimonide-based thermoelectric alloy

Abstract

The invention discloses an indium antimonide-based thermoelectric alloy, the chemical formula of the indium antimonide-based thermoelectric alloy is InSb1-xBix, x is 0.02-0.05, the invention also discloses a preparation method, and the preparation method comprises the following steps: (1) weighing alloy raw materials indium particles and antimony particles according to a molar ratio of 1: 1.01-1: 1.03, adding bismuth powder according to a molar ratio of x: 1 to indium, and uniformly mixing the indium particles, the antimony particles and the bismuth powder; through reasonable doping of bismuth, the alloy has high conductivity, high Seebeck coefficient and low thermal conductivity, and the thermoelectric performance of the alloy is improved.

Description

Technical Field

[0001] This invention relates to the field of thermoelectric alloy technology, and more specifically to an indium antimonide-based thermoelectric alloy. Background Technology

[0002] Thermoelectric materials utilize the directional movement of charge carriers and phonons within solid materials to achieve the transfer of electricity and heat, thus directly converting electrical energy into thermal energy. This energy conversion method allows for the recovery and reuse of waste heat, improving energy efficiency and reducing carbon emissions. Furthermore, thermoelectric materials offer advantages such as small size and noiselessness, making them a focus of widespread research. The thermoelectric properties of thermoelectric materials are primarily determined by the dimensionless thermoelectric figure of merit (ZT). A higher ZT value indicates a higher thermoelectric conversion efficiency. ZT = SσT / κ, where S is the Seebeck coefficient, σ is the electrical conductivity, T is the absolute temperature, and κ is the thermal conductivity. As shown in the formula, a high ZT value requires high electrical conductivity, a high Seebeck coefficient, and low thermal conductivity.

[0003] Current thermoelectric alloy materials mainly include Bi2Te3-based alloys, PbTe-based alloys, and Si-Ge alloys. Indium antimonide (InSb)-based thermoelectric alloys, as III-V group semiconductor materials, have irreplaceable advantages in the aerospace field due to their radiation resistance and high-temperature stability. They also have high electron mobility and a direct bandgap structure, which are theoretically suitable for thermoelectric conversion. However, their initial performance is limited by high thermal conductivity, resulting in a low thermoelectric figure of merit (ZT). Summary of the Invention

[0004] The purpose of this invention is to provide an indium antimonide-based thermoelectric alloy to solve the problems existing in the prior art.

[0005] To achieve the above objectives, the present invention provides the following technical solution: an indium antimonide-based thermoelectric alloy, wherein the chemical formula of the indium antimonide-based thermoelectric alloy is InSb1-xBix, where x = 0.02 to 0.05.

[0006] The present invention also provides a method for preparing the indium antimonide-based thermoelectric alloy, comprising the following steps: (1) weighing indium granules and antimony granules in a molar ratio of 1:1.01 to 1:1.03, adding bismuth powder in a molar ratio of x:1 to indium, and mixing the indium granules, antimony granules and bismuth powder evenly; (2) putting the above mixed raw materials into a vacuum furnace and evacuating the furnace to 10°C. -2 After Pa, argon gas with a purity ≥99.999% is introduced, and the temperature is raised to 700~800℃ at a rate of 20±2℃ / min, held for 3~4h, and then cooled to room temperature at a rate of 5±2℃ / min to form an alloy ingot; (3) the alloy ingot is crushed to a particle size <2mm, and then heated at 500~600℃ with a vacuum degree of 10 -3Annealed at Pa for 12-14 hours, then ground to 200 mesh powder, cold isostatically pressed at 200 MPa, and then sintered at 600-650℃ under normal pressure for 2-3 hours to obtain indium antimonide-based thermoelectric alloy.

[0007] As a preferred embodiment of this technical solution, the particle size of the indium and antimony particles in step (1) is 1-3 mm.

[0008] As a preferred embodiment of this technical solution, the purity of the indium particles, antimony particles and bismuth powder in step (1) is ≥99.99%.

[0009] Compared with the prior art, the present invention has the following beneficial effects:

[0010] 1. This invention involves doping indium antimonide with Bi, where Bi atoms partially replace Sb atoms in the indium antimonide lattice, introducing a shallow donor level (ionization energy of approximately 0.03 eV), significantly increasing the carrier concentration (from an intrinsic value of 10 eV). 16 cm -3 Upgraded to 10 19 cm -3 This increases electrical conductivity.

[0011] 2. Bi doping leads to lattice distortion, forming point defects and localized stress fields, effectively scattering mid-to-high frequency phonons, and reducing the lattice thermal conductivity from 17.5 W / (m●K) to 5.2 W / (m●K).

[0012] 3. The BiSb second phase precipitated at the grain boundaries forms a nanoscale barrier, selectively filtering low-energy carriers and increasing the Seebeck coefficient by about 30%. Detailed Implementation

[0013] The technical solutions of the present invention will be clearly and completely described below with reference to specific embodiments. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0014] This invention discloses an indium antimonide-based thermoelectric alloy, the chemical formula of which is InSb1-xBix, where x = 0.02 to 0.05. The preparation method of the indium antimonide-based thermoelectric alloy includes the following steps: (1) Weighing indium granules and antimony granules in a molar ratio of 1:1.01 to 1:1.03, compensating for excess antimony granules to prevent loss, and adding bismuth powder in a molar ratio of x:1 to indium, mixing the indium granules, antimony granules and bismuth powder evenly, the particle size of the indium granules and antimony granules being 1 to 3 mm, and the purity of the indium granules, antimony granules and bismuth powder being ≥99.99%; (2) Putting the above mixed raw materials into a vacuum furnace and evacuating to 10-2 After Pa, argon gas with a purity ≥99.999% is introduced, and the temperature is raised to 700~800℃ at a rate of 20±2℃ / min, held for 3~4h, and then cooled to room temperature at a rate of 5±2℃ / min to form an alloy ingot; (3) the alloy ingot is crushed to a particle size <2mm, and then heated at 500~600℃ with a vacuum degree of 10 -3 Annealing at Pa for 12-14 hours promotes uniform diffusion of bismuth atoms and formation of antimony nanoprecipitates. After annealing, the powder is ground to 200 mesh, cold isostatically pressed at 200 MPa, and then sintered at 600-650℃ under normal pressure for 2-3 hours to obtain an indium antimonide-based thermoelectric alloy with a density of over 98%.

[0015] Example 1: An indium antimonide-based thermoelectric alloy with the chemical formula InSb1-xBix, where x is 0.02, 0.03, 0.04, or 0.05. The preparation method of the indium antimonide-based thermoelectric alloy includes the following steps: (1) Weigh the alloy raw materials indium granules and antimony granules in a molar ratio of 1:1.01, and add bismuth powder in a molar ratio of (0.02, 0.03, 0.04, or 0.05):1 with indium. Mix the indium granules, antimony granules, and bismuth powder evenly. The particle size of the indium granules and antimony granules is 1-3 mm, and the purity of the indium granules, antimony granules, and bismuth powder is 99.99%. (2) Put the above mixed raw materials into a vacuum furnace and evacuate to 10 °C. -2 After Pa, 99.999% pure argon gas is introduced, and the temperature is raised to 700℃ at a rate of 22℃ / min, held for 3 hours, and then cooled to room temperature at a rate of 7℃ / min to form an alloy ingot; (3) the alloy ingot is crushed to a particle size <2mm, and then heated at 500℃ and a vacuum degree of 10 -3 Annealed for 12 hours under Pa conditions, then ground to 200 mesh powder, cold isostatically pressed at 200 MPa, and then sintered at 600℃ and normal pressure for 3 hours to obtain indium antimonide-based thermoelectric alloy.

[0016] Example 2: The difference between this example and Example 1 is that in step (2), the temperature is increased to 800°C at a rate of 18°C / min, held for 4 hours, and then cooled to room temperature at a rate of 3°C / min.

[0017] Example 3: The difference between this example and Example 1 is that in step (3), the annealing is carried out at 600°C and a vacuum of 10-3 Pa for 14 hours.

[0018] Example 4: The difference between this example and Example 1 is that in step (3), the sintering is carried out at 650°C and atmospheric pressure for 2 hours.

[0019] Example 5: The difference between this example and Example 1 is that in step (1), the molar ratio of indium particles and antimony particles in the alloy raw materials is 1:1.03.

[0020] Example 6: The difference between this example and Example 1 is that in step (1) the alloy raw materials indium particles and antimony particles are in a molar ratio of 1:1.02.

[0021] Example 7: The difference between this example and Example 1 is that step (2) is to heat to 750°C at a rate of 20°C / min and keep warm for 3 hours.

[0022] Example 8: The difference between this example and Example 1 is that in step (3), the annealing is carried out at 650°C and a vacuum of 10-3 Pa for 13 hours.

[0023] The samples with x=0.02, 0.03, and 0.05 from Example 1 were used for testing. The control group was pure InSb. The test temperatures were 300K, 400K, 500K, 600K, and 693K. The test accuracy was: electrical conductivity ±2%, thermal conductivity ±5%, and power factor ±2%.

[0024] Conductivity test results (unit: 10) 4 S / m)

[0025]

[0026] Analysis: The conductivity of all samples gradually decreased with increasing temperature. Bi doping significantly improved the conductivity, with the highest conductivity at x=0.03. At x=0.05, the conductivity was slightly lower than that at x=0.03 due to the increased lattice distortion caused by excessive Bi.

[0027] Power factor test results (unit: µW●cm) -1 ●k -2 )

[0028]

[0029] Analysis: The power factor continues to increase with increasing temperature, and the sample with x=0.03 has the highest power factor across the entire temperature range.

[0030] Thermal conductivity test results (unit: W·cm) -1 ●k -1 )

[0031]

[0032] Analysis: Thermal conductivity gradually decreases with increasing temperature (at low temperatures, lattice thermal conductivity is dominant, while phonon scattering increases with increasing temperature); Bi doping significantly reduces thermal conductivity through "point defect scattering". The sample with x=0.05 has the highest Bi content, the most obvious lattice distortion, and the lowest thermal conductivity; however, electronic thermal conductivity contributes slightly with increasing temperature, and the rate of decrease in thermal conductivity slows down at 693K.

[0033] ZT value test results (units not specified)

[0034]

[0035] Analysis: The ZT value increases exponentially with increasing temperature, reaching its highest value at 693K when x=0.03.

[0036] In summary, the best overall performance was achieved with a Bi doping concentration of 0.03, with a ZT value of 0.46 at 693 K, meeting the practical requirements for medium-temperature waste heat recovery. All doped samples showed significant ZT value improvements in the 500–693 K range, making them suitable for scenarios such as automotive exhaust (400–600 K) and industrial kilns (500–700 K). This preparation method effectively suppresses component segregation and ensures uniform Bi solid solution, providing a structural basis for performance optimization.

[0037] Finally, it should be noted that the above-described embodiments are merely specific implementations of the present invention, used to illustrate the technical solutions of the present invention, and not to limit it. The scope of protection of the present invention is not limited thereto. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that any person skilled in the art can still modify or easily conceive of changes to the technical solutions described in the foregoing embodiments within the technical scope disclosed in the present invention, or make equivalent substitutions for some of the technical features; and these modifications, changes, or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention, and should all be covered within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. An indium antimonide-based thermoelectric alloy, characterized in that: The chemical formula of the indium antimonide-based thermoelectric alloy is InSb1-xBix, where x = 0.02 to 0.

05.

2. A method for preparing the indium antimonide-based thermoelectric alloy according to claim 1, characterized in that, The process includes the following steps: (1) Weighing indium and antimony granules in a molar ratio of 1:1.01 to 1:1.03, adding bismuth powder in a molar ratio of x:1 to indium, and mixing the indium granules, antimony granules, and bismuth powder evenly; (2) Putting the above mixed raw materials into a vacuum furnace and evacuating it to 10°C. -2 After Pa, argon gas with a purity ≥99.999% is introduced, and the temperature is raised to 700~800℃ at a rate of 20±2℃ / min, held for 3~4h, and then cooled to room temperature at a rate of 5±2℃ / min to form an alloy ingot; (3) the alloy ingot is crushed to a particle size <2mm, and then heated at 500~600℃ with a vacuum degree of 10 -3 Annealed at Pa for 12-14 hours, then ground to 200 mesh powder, cold isostatically pressed at 200 MPa, and then sintered at 600-650℃ under normal pressure for 2-3 hours to obtain indium antimonide-based thermoelectric alloy.

3. The method for preparing the indium antimonide-based thermoelectric alloy according to claim 2, characterized in that: The particle size of the indium and antimony particles in step (1) is 1-3 mm.

4. The method for preparing the indium antimonide-based thermoelectric alloy according to claim 2, characterized in that: The purity of the indium granules, antimony granules and bismuth powder in step (1) is ≥99.99%.

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