Powder for manufacturing BITE-based N-type thermoelectric material, BITE-based N-type thermoelectric material manufactured using the powder, and manufacturing method thereof

Abstract

The present invention relates to a powder for manufacturing a BiTe-based n-type thermoelectric material, a BiTe-based n-type thermoelectric material manufactured using the powder, and a manufacturing method thereof. More specifically, the present invention relates to a method for manufacturing a BiTe-based n-type thermoelectric material by using Bi, Sb, and Te. x Sb 2-x The present invention relates to a powder for producing a BiTe-based n-type thermoelectric material, which has a composition of Te3 (where x is 1.0≦x≦1.9) but contains Te vacancy defects, and in which an excess amount of Te is contained in the crystal grains and crystal grain system; a BiTe-based n-type thermoelectric material produced using the powder; and a method for producing the material.

Description

[Technical Field]

[0001] The present invention relates to a powder for producing a BiTe-based n-type thermoelectric material, a BiTe-based n-type thermoelectric material produced using the powder, and a method for producing the material. [Background technology]

[0002] Thermoelectric materials are materials that embody the thermoelectric phenomenon, which allows for the production of electrical energy using discarded heat sources such as exhaust and waste heat, and also for active cooling and heating using electrical energy. Therefore, thermoelectric phenomena can be used in fields such as thermoelectric power generation using waste heat from ships, factories, and automobiles, energy harvesters for home power generation in IoT devices, and in fields such as precise temperature control and noiseless refrigerators, water purifiers, and electric vehicle HVAC systems to improve energy efficiency. Therefore, research is ongoing to improve the physical properties of thermoelectric materials for use in the above-mentioned fields.

[0003] Meanwhile, to realize thermoelectric phenomena, a structure in which P-type and N-type thermoelectric semiconductors are alternately arranged is required. Bi-Te thermoelectric materials are currently commercially available, and Bi-Sb-Te thermoelectric materials, which are P-type thermoelectric materials alloyed with Sb, are known to exhibit excellent properties. Currently, P-type Bi-Sb-Te has an excellent dimensionless figure of merit (ZT) value of 1.86, expressed by the following formula, by minimizing lattice thermal conductivity by forming dislocations within the material and activating phonon scattering in various wavelength ranges (Science 348 ISSUE 6230, pp. 109-114).

[0004]

number

[0005] (σ: electrical conductivity, κ: thermal conductivity, α: Seebeck coefficient, T: absolute temperature)

[0006] However, in comparison, n-type thermoelectric materials are sensitive to compositional changes due to the high volatility of Se and Te, the commonly used n-type dopants, and have a wide range of variations in electrical conductivity depending on the composition, resulting in relatively lower thermoelectric properties than p-type materials. Bi-Te-Se thermoelectric materials, in which Se is alloyed, are the most representative. However, these thermoelectric materials are difficult to apply the methods used for p-type materials, and their ZT values ​​generally remain at or below 0.8, meaning that technological development to improve this is necessary. Furthermore, while existing manufacturing methods for p-type materials can minimize thermal conductivity and improve thermoelectric figure of merit (ZT), there are limitations on improving electrical conductivity, which is a key factor in increasing efficiency in thermoelectric power generation.

[0007] The present inventors have been researching the development of new n-type thermoelectric materials that can replace existing Bi-Te-Se-based n-type thermoelectric materials. They found that the more antisite defects (Bi or Sb atoms) present in a Bi-Te material, the more holes are formed, resulting in p-type characteristics. On the other hand, the more vacancies (vacancies) present in a Bi-Te material, the more electrons are generated, resulting in n-type characteristics. Furthermore, after adding an excess amount of Te, the Bi-Te material was pressure-sintered. The process of removing the excess Te by liquid phase induced significant stress within the material. At the same time, the excess Te created a Te-rich environment. Under certain deformation conditions and compositions, the antisite defects (Bi or Sb atoms) formed, resulting in the formation of additional electrons. The formation of a large number of electron-generating antisite defects within the material increased the carrier density, further improving electrical conductivity. Furthermore, when a large number of atomic defects are formed inside the material, phonon scattering becomes more active compared to materials that have not been treated with atomic defects, ensuring a reduction in lattice thermal conductivity due to lattice vibration.The large stress induced inside the material causes dislocation networks, a type of line defect, to form in the thermoelectric material at grain boundaries or within crystal grains, maximizing the thermal phonon scattering effect in various wavelength bands and further reducing thermal conductivity.Finally, we developed a BiTe-based n-type thermoelectric material with improved thermoelectric properties, thereby completing the present invention. Summary of the Invention [Problem to be solved by the invention]

[0008] An object of one aspect is to provide a powder for producing a BiTe-based n-type thermoelectric material, a BiTe-based n-type thermoelectric material produced using the powder, and a method for producing the same. [Means for solving the problem]

[0009] In order to achieve the above object, in one aspect, Bi x Sb 2-x Provided is a powder for producing a BiTe-based n-type thermoelectric material, which is a BiTe-based polycrystalline powder containing crystal grains having a composition of Te3 (where x is 1.0≦x≦1.9), with Te filling the spaces between the crystal grains.

[0010] Here, the BiTe-based polycrystalline powder is preferably Bi x Sb 2-x It may include crystal grains having a composition of Te3, where x is 1.5≦x≦1.9.

[0011] In another aspect, The powder for manufacturing the BiTe-based n-type thermoelectric material is subjected to spark plasma sintering to produce Bi. x Sb 2-x Provided is a BiTe-based n-type thermoelectric material that includes crystal grains having a composition of Te3 (where x is 1.0≦x≦1.9) and has atomic defects and line defects.

[0012] The BiTe-based polycrystalline n-type thermoelectric material includes anti-site defects and dislocation networks formed in the grains or grain boundaries.

[0013] Here, the antisite defects are located at the Bi or Sb site by substitution of Te.

[0014] The dislocation network has a net structure in which a plurality of dislocations are interconnected.

[0015] The BiTe-based n-type thermoelectric material can exhibit n-type thermoelectric properties at room temperature to 300°C.

[0016] The BiTe-based n-type thermoelectric material has a thermal conductivity of 20×10 4 S / m~30×104 It can exhibit an electrical conductivity of S / m.

[0017] On the other hand, Bi x Sb 2-x A step of manufacturing a polycrystalline n-type powder material containing crystal grains having a composition of Bi x Sb 2-x Te3 (where x satisfies 1.0 ≤ x ≤ 1.9) and having a large number of Te vacancy defects, and A method for manufacturing a BiTe-based n-type thermoelectric powder, which includes forming a molded body after mixing the n-type powder material and an excessive amount of Te material, and performing a melt spinning process on the molded body to form the powder for manufacturing the BiTe-based n-type thermoelectric material.

[0018] On the other hand, Bi x Sb 2-x A step of manufacturing an n-type powder material containing crystal grains having a composition of Bi x Sb 2-x Te3 (where x satisfies 1.0 ≤ x ≤ 1.9) and having a large number of Te vacancy defects, A step of forming a molded body after mixing the n-type powder material and an excessive amount of Te powder, performing a melt spinning process on the molded body to form a film-shaped powder, and A method for manufacturing a BiTe-based n-type thermoelectric material, which includes pulverizing the film-shaped powder and then performing a spark plasma sintering process to form the BiTe-based n-type thermoelectric material.

[0019] Here, the step of manufacturing the n-type powder material Bi, Sb, Te, and a compound containing one or more of them are weighed and mixed so as to match the composition of Bi x Sb 2-x Te3 (where x satisfies 1.0 ≤ x ≤ 1.9), and then vacuum sealed, and x Sb 2-x ​​​​​​​​

[0021] In another aspect, A thermoelectric element including the BiTe-based n-type thermoelectric material is provided.

[0022] The thermoelectric element is a thermoelectric power generating element or a thermoelectric cooling / heating element. [Effects of the Invention]

[0023] The BiTe-based n-type thermoelectric material of the present invention has the advantage of being able to realize low thermal conductivity while having improved electrical conductivity, ultimately exhibiting excellent thermoelectric properties.

[0024] The method for manufacturing a BiTe-based n-type thermoelectric material of the present invention is characterized by its ability to increase the charge amount by utilizing atomic defects in the Bi-Te-based thermoelectric material and to realize the effect of activating phonon scattering by dispersing line defects within the material.

[0025] Therefore, the BiTe-based n-type thermoelectric material of the present invention can be utilized in ship waste heat recovery and energy harvesting, and can be used as a core material for solar hybrid energy harvesters. When used as an n-type thermoelectric material for thermoelectric elements that require precise temperature control, such as water purifiers, low-power temperature control parts for electric vehicles, semiconductor wafer temperature control devices, noiseless refrigerators, wine cellars, electric vehicle battery temperature control, and high-efficiency HVAC (Heating, Ventilating, and Air Conditioning), it has the advantage of being able to improve the performance of the thermoelectric elements.

[0026] The effects of the present invention are not limited to those mentioned above, and other effects not mentioned will be clearly understood by those skilled in the art from the following description. [Brief explanation of the drawings]

[0027] [Figure 1] 1 is a flowchart of a manufacturing process for a BiTe-based n-type thermoelectric material according to an example. [Figure 2A]FIG. 1 is a diagram schematically illustrating a unit cell forming the crystal structure of a Bi—Sb—Te material. [Figure 2B] This is a graph comparing the formation energies of various atomic defects that are formed when compressive deformation is applied to Bi1.7Sb0.3Te3 when the amount of Te in the composition is the thermodynamically minimum allowable amount (Te-poor), calculated according to the Fermi level. [Figure 2C] This is a graph comparing the formation energies of various atomic defects that are formed when compressive deformation is applied to Bi0.3Sb1.7Te3 when the amount of Te in the composition is the maximum amount allowed thermodynamically (Te-rich), calculated according to the Fermi level. [Figure 3] 1A and 1B are a schematic diagram and a partially enlarged view of a powder for a BiTe-based n-type thermoelectric material produced in accordance with an example. [Figure 4A] 1 is a photograph of the surface of the film-shaped powder produced in the example. [Figure 4B] This is an enlarged photograph of the boxed area in Figure 4A. [Figure 4C] FIG. 4B is an EDS component mapping image of the region. [Figure 4D] 1 is a cross-sectional photograph of a film-shaped powder produced in an example. [Figure 5A] 1 is a photograph of the surface and cross section of a BiTe-based n-type thermoelectric material according to an example, observed with a scanning electron microscope (SEM). 2 is a photograph of the cross section of an n-type thermoelectric material (initial state) produced in Comparative Example 1. [Figure 5B] 1 is a photograph of the surface and cross section of a BiTe-based n-type thermoelectric material according to an example, observed with a scanning electron microscope (SEM). 2 is a photograph of a cross section of an n-type thermoelectric material (Te 15%) produced in Example 2. [Figure 5C] 1 is a photograph of the surface and cross section of a BiTe-based n-type thermoelectric material according to an example, observed with a scanning electron microscope (SEM). 2 is a photograph of the cross section of the n-type thermoelectric material (Te 25%) produced in Example 1. [Figure 5D] 1 is a photograph of the surface and cross section of a BiTe-based n-type thermoelectric material according to an example, observed with a scanning electron microscope (SEM). 2 is a photograph of the surface of an n-type thermoelectric material (initial state) produced in Comparative Example 1. [Figure 5E] 1 is a photograph of the surface and cross section of a BiTe-based n-type thermoelectric material according to an example, observed with a scanning electron microscope (SEM). 2 is a photograph of the surface of an n-type thermoelectric material (Te 15%) produced in Example 2. [Figure 5F] 1 is a photograph of the surface and cross section of a BiTe-based n-type thermoelectric material according to an example, observed with a scanning electron microscope (SEM). 2 is a photograph of the surface of an n-type thermoelectric material (Te 25%) produced in Example 1. [Figure 6A] 1 shows the EBSD analysis results of the n-type thermoelectric material (initial state) produced in Comparative Example 1, and is an image quality (IQ) map value that indicates the clarity of the Kikuchi diffraction pattern. [Figure 6B] 1 shows the results of EBSD analysis of the n-type thermoelectric material (initial state) produced in Comparative Example 1, which is an inverse pole figure (IPF) map showing the orientation distribution of the grain boundaries. [Figure 6C] 1 is a graph showing the size distribution of crystal grain boundaries calculated based on the EBSD analysis results of the n-type thermoelectric material (initial state) produced in Comparative Example 1. [Figure 6D] 1 shows the EBSD analysis results of the n-type thermoelectric material (Te 25%) produced in Example 1, and is an image quality (IQ) map value that indicates the clarity of the Kikuchi diffraction pattern. [Figure 6E] 1 shows the results of EBSD analysis of the n-type thermoelectric material (Te 25%) produced in Example 1, which is an inverse pole figure (IPF) map showing the orientation distribution of the grain boundaries. [Figure 6F] 1 is a graph showing the size distribution of crystal grain boundaries calculated based on the EBSD analysis results of the n-type thermoelectric material (Te 25%) produced in Example 1. [Figure 7A] 1 shows data comparing the electrical conductivities of BiTe-based n-type thermoelectric materials according to examples and comparative examples. [Figure 7B] 1 shows data comparing the Seebeck coefficients of BiTe-based n-type thermoelectric materials according to examples and comparative examples. [Figure 7C] 1 shows data comparing the thermal conductivities of BiTe-based n-type thermoelectric materials according to examples and comparative examples. [Figure 7D]1 shows data comparing the dimensionless figure of merit (ZT) of the BiTe-based n-type thermoelectric materials according to Examples and Comparative Examples. [Figure 8A] 1 shows data comparing the charge densities of the BiTe-based n-type thermoelectric materials according to Examples and Comparative Examples. [Figure 8B] 1 shows data comparing the charge mobility of BiTe-based n-type thermoelectric materials according to examples and comparative examples. [Figure 9A] 1 is a transmission electron microscope (TEM) photograph of a dislocation network formed in a BiTe-based n-type thermoelectric material according to an example, and is a TEM photograph of the inside of the n-type thermoelectric material produced in Example B-1. [Figure 9B] 9B is a transmission electron microscope (TEM) photograph of a dislocation network formed in a BiTe-based n-type thermoelectric material according to an example, and is a TEM photograph taken in "Two beam dark field image" mode of the boxed area in FIG. 9A for detailed observation of the dislocation network. [Figure 9C] 1 is a transmission electron microscope (TEM) photograph of a dislocation network formed in a BiTe-based n-type thermoelectric material according to an example, and a TEM photograph of another part inside the n-type thermoelectric material produced in Example B-1. [Figure 9D] 9C is a TEM photograph of a dislocation network formed in a BiTe-based n-type thermoelectric material according to an example, taken with a transmission electron microscope (TEM). The TEM photograph was taken in "Two beam dark field image" mode of the interface between the two crystal grains in FIG. 9C for detailed observation of the dislocation network. [Figure 10A] 1 is a photograph of a dislocation network formed in a BiTe-based n-type thermoelectric material according to an example, observed with a transmission electron microscope (TEM), showing crystal grains. [Figure 10B] 1 is a photograph of a dislocation network formed in a BiTe-based n-type thermoelectric material according to an example, observed with a scanning transmission electron microscope (STEM), showing a dislocation network array present between crystal grains. [Figure 11]1 shows data comparing dimensionless figures of merit depending on the added Te content of BiTe-based n-type thermoelectric materials according to examples. DETAILED DESCRIPTION OF THE INVENTION

[0028] Hereinafter, preferred embodiments of the present invention will be described with reference to the accompanying drawings. However, the embodiments of the present invention can be modified in several different forms, and the scope of the present invention is not limited to the embodiments described below. Furthermore, the following embodiments are provided to more completely explain the present invention to those having average knowledge in the art. Furthermore, throughout the specification, when a word "comprises" a certain element, it does not mean that other elements are excluded, but that other elements may also be included, unless otherwise specified.

[0029] In one aspect, Bi x Sb 2-x Provided is a powder for producing a BiTe-based n-type thermoelectric material, which is a BiTe-based polycrystalline powder containing crystal grains having a composition of Te3 (where x is 1.0≦x≦1.9), with Te filling the spaces between the crystal grains.

[0030] Hereinafter, a powder for producing a BiTe-based n-type thermoelectric material according to one aspect will be described in detail.

[0031] FIG. 3 is a schematic diagram of a BiTe-based n-type thermoelectric material powder produced in accordance with an example, and a partially enlarged view thereof.

[0032] Referring to FIG. 3, the powder according to one embodiment is Bi x Sb 2-x It is characterized by including crystal grains having a composition of Te3 (where x is 1.0≦x≦1.9, preferably 1.5≦x≦1.9), and containing an excess amount of Te between the crystal grains.

[0033] The powder is Bi x Sb 2-xThe film-shaped (ribbon-shaped) powder (MS) can be formed by mixing a polycrystalline n-type powder material containing crystal grains having a composition of Te3 (where x is 1.0≦x≦1.9) with an excess amount of Te material, and then melt-spinning the resulting molded body.

[0034] The film-shaped powder may be in the form of a polygon with a width and length of 30 to 300 μm and a thickness of 5 to 50 μm.

[0035] The powder according to one embodiment is a powder for producing a BiTe-based n-type thermoelectric material described below, and is characterized in that an excess amount of Te is filled between the crystal grains.

[0036] The powder may have Te vacancies as the main atomic defects.

[0037] The excess Te filling the spaces between the crystal grains of the powder escapes to the outside of the mold during the sintering process for manufacturing the thermoelectric material, thereby inducing strong stress inside the material and forming anti-site defects and dislocation networks in the thermoelectric material.

[0038] More specifically, Bi x Sb 2-x When a BiTe-based powder with a composition of Te3 (where x is 1.0≦x≦1.9) satisfies the condition of containing an excess amount of Te and is subjected to compressive deformation by pressure sintering, antisite defects are formed in which Te is filled at the Bi or Sb site, which is the thermodynamically most stable atomic defect (see FIG. 2A). When many such antisite defects are formed, the electron density in the thermoelectric material increases, resulting in the formation of a thermoelectric material with improved electrical conductivity. In addition, the excess Te present between the crystal grains is converted into a liquid state during the spark plasma sintering process and escapes from between the crystal grains to the outside of the mold due to pressure, instantaneously dissolving the Bi. x Sb 2-xTe3 crystal grains bond together and sintering progresses. At this time, a spark plasma sintering process is performed to accelerate sintering, and bonding occurs between crystal grains while retaining interstitial deformation energy, easily forming dislocations, which are line defects. The dislocations formed in this way can realize the effect of activating phonon scattering, resulting in the formation of a thermoelectric material with low thermal conductivity.

[0039] In another aspect, The powder for manufacturing a BiTe-based n-type thermoelectric material is subjected to spark plasma sintering to produce Bi, Sb, and Te. x Sb 2-x Provided is a BiTe-based polycrystalline n-type thermoelectric material that includes crystal grains having a composition of Te3 (where x is 1.0≦x≦1.9) and has atomic defects and line defects.

[0040] An n-type BiTe-based thermoelectric material according to one embodiment will be described in detail below.

[0041] According to an embodiment, the BiTe-based n-type thermoelectric material has atomic defects and line defects, and the atomic defects may include anti-site defects, and the line defects may include dislocation networks formed in the crystal grains or grain boundaries.

[0042] In one embodiment, the BiTe-based n-type thermoelectric material is a material containing Bi, Sb, and Te. x Sb 2-x The material is a BiTe-based n-type thermoelectric material containing crystal grains with a composition of Te3 (where x is 1.0≦x≦1.9) and having Te vacancy defects.

[0043] The crystal grains contain Bi, Sb and Te. x Sb 2-x It may have a composition of Te3, where x is 1.0≦x≦1.9.

[0044] As an example, the composition of the n-type thermoelectric material is Bi 1.9 b 0.1 Te 3.0Bi 1.7 b 0.3 Te 3.0 Bi 1.5 b 0.5 Te 3.0 However, preferably Bi 1.7 b 0.3 Te 3.0 It could be.

[0045] Bi x Sb 2-x Thermoelectric materials with a Te3 crystal structure (where x is 1.0≦x≦1.9) exhibit P-type characteristics when Bi or Sb is substituted for Te, resulting in the formation of holes, while when there are Te vacancy defects, electrons are generated, resulting in N-type characteristics (see the formula below).

[0046]

number

[0047] The BiTe-based n-type thermoelectric material according to one embodiment can exhibit improved electrical conductivity due to the presence of more Te vacancies.

[0048] The BiTe-based n-type thermoelectric material according to one embodiment has a conductivity of about 10×10 19 cm -3 or more, preferably 10 to 12 × 10 19 cm -3 electron density (n) or approximately 220-260 cm 2 It can have a charge mobility (μ) of 1 / V·s.

[0049] A BiTe-based n-type thermoelectric material according to one embodiment is characterized by including anti-site defects and a dislocation network formed at grain boundaries to have higher thermoelectric properties.

[0050] The BiTe-based n-type thermoelectric material according to one embodiment includes the anti-site defects and dislocation networks formed at grain boundaries, and therefore exhibits increased electrical conductivity and charge concentration compared to a material that does not include these (initial state), while also exhibiting the opposing characteristic of decreased thermal conductivity, and ultimately has the advantage of exhibiting a significantly high dimensionless index (ZT).

[0051] Here, the anti-site defect is located at a Bi or Sb site by substitution of Te, and the BiTe-based n-type thermoelectric material according to one embodiment has the anti-site defect, which can generate more electrons and increase the charge density, thereby further improving the electrical conductivity.

[0052] The dislocation network formed at the grain boundaries between the crystal grains has a net structure in which a plurality of dislocations are interconnected, and the net structure may have polygonal, e.g., hexagonal, voids and may be interconnected in a zigzag pattern. The dislocation network may have a structure in which a plurality of dislocations are interconnected with a width of 100 nm to 500 nm and a length of 10 μm to 500 μm.

[0053] The BiTe-based n-type thermoelectric material according to one embodiment can further reduce thermal conductivity by phonon scattering through the dislocation network.

[0054] The BiTe-based n-type thermoelectric material has a thermal conductivity of 10 × 10 4 S / m~30×10 4 S / m, and preferably 15×10 4 S / m~30×10 4 It can exhibit electrical conductivity of 500 S / m, and can therefore be used to realize thermoelectric power generation elements by utilizing its high electrical conductivity properties.

[0055] Furthermore, the BiTe-based n-type thermoelectric material can exhibit a Seebeck coefficient of −100 μV / K to −140 μV / K at room temperature.

[0056] Furthermore, the BiTe-based n-type thermoelectric material can exhibit a thermal conductivity of 1.3 W / m·K to 1.0 W / m·K at room temperature, and can exhibit a thermal conductivity of 1.2 W / m·K to 1.0 W / m·K.

[0057] Furthermore, the dimensionless figure of merit (ZT) of the BiTe-based n-type thermoelectric material according to an embodiment may be 1 or more, preferably 1 to 1.3, 1.1 to 1.3, or 1.2 to 1.3.

[0058] In addition, the BiTe-based n-type thermoelectric material can ensure thermal conductivity of 1.0 W / m K or less at room temperature by adjusting its electrical conductivity, and therefore the dimensionless figure of merit can be adjusted to a level of 1.3 or more.

[0059] Therefore, the BiTe-based n-type thermoelectric material according to one embodiment can be utilized in ship waste heat recovery, energy harvesting, etc., and can be used as a core material for solar hybrid energy harvesters. When used as an n-type thermoelectric material for thermoelectric elements that require precise temperature control, such as water purifiers, low-power temperature control parts for electric vehicles, semiconductor wafer temperature control devices, noiseless refrigerators, wine cellars, electric vehicle battery temperature control, and high-efficiency HVAC (Heating, Ventilating, and Air Conditioning), the material has the advantage of being able to improve the performance of the thermoelectric elements.

[0060] In another aspect, Bi x Sb 2-xThe present invention provides a method for producing a powder for use in producing a BiTe-based n-type thermoelectric material, the method comprising the steps of: producing a polycrystalline n-type powder material containing crystal grains having a composition of Te3 (where x is 1.0≦x≦1.9) and having a large amount of Te vacancy defects; and mixing the n-type powder material with an excess amount of Te material, forming a compact, and subjecting the compact to a melt spinning process, thereby forming the powder for use in producing a BiTe-based n-type thermoelectric material.

[0061] Hereinafter, each step of a method for producing a powder for producing a BiTe-based n-type thermoelectric material according to one embodiment will be described in detail.

[0062] In one embodiment, a method for producing a powder for producing a BiTe-based n-type thermoelectric material is x Sb 2-x The method includes a step of producing an n-type powder material containing crystal grains having a composition of Te3 (where x is 1.0≦x≦1.9) but with a large amount of Te vacancy defects to produce an n-type thermoelectric material.

[0063] Here, the n-type powder material has a density of about -1 × 10 after sintering. 19 cm -3 or more, preferably -2 to -10 × 10 19 cm -3 The density of charge (n) is about 120 cm 2 / V·s or more, preferably about 120 to 280 cm 2 It can have a charge mobility (μ) of 1 / V·s.

[0064] For this purpose, the process for producing the n-type powder material includes: Bi, Sb, Te and compounds containing one or more of these x Sb 2-x Te3 (wherein x is 1.0≦x≦1.9), and then vacuum-sealing the mixture; The step may include milling the vacuum-sealed mixture or an ingot of the mixture to form a powder.

[0065] Next, a manufacturing method of a powder for manufacturing a BiTe-based n-type thermoelectric material according to one embodiment includes the steps of mixing the n-type powder material and an excess amount of Te material, forming a compact, and then performing a melt spinning process on the compact to form a film-shaped powder.

[0066] By the above process, Bi x Sb 2-x A film-shaped powder having a morphology containing an excess amount of Te between crystal grains having a composition of Te3 (where x is 1.0≦x≦1.9) can be formed.

[0067] For this purpose, the n-type powder material and an excess amount of Te material can be mixed and molded by a press molding method, and the molded body can be melted in a chamber with an inert atmosphere and then sprayed onto a roller rotating at 30 to 100 m / s. Through this process, Bi, Sb, and Te can be mixed into Bi x Sb 2-x It is possible to form a film-shaped (ribbon-shaped) powder (MS) having a morphology in which excess Te is contained at the grain boundary of crystal grains having a composition of Te3 (where x is 1.0≦x≦1.9).

[0068] Here, the mixing of the powder material and the excess amount of Te material may be 5 to 30 wt % of Te material, 10 to 30 wt %, or 20 to 30 wt % of Te material, based on the total weight of the mixture of the powder material and the excess amount of Te material.

[0069] In another aspect, Bi x Sb 2-x producing a polycrystalline n-type powder material comprising crystal grains having a composition of Te3, where x is 1.0≦x≦1.9; a step of forming a compact by mixing the n-type powder material and an excess amount of Te material, and then subjecting the compact to a melt spinning process to form a film-shaped powder; The present invention provides a method for producing a BiTe-based n-type thermoelectric material, which includes a step of pulverizing the film-shaped powder, followed by a spark plasma sintering step to form the BiTe-based n-type thermoelectric material.

[0070] Hereinafter, each step of a method for manufacturing a BiTe-based n-type thermoelectric material according to one embodiment will be described in detail.

[0071] FIG. 1 is a diagram schematically illustrating a manufacturing process of a BiTe-based n-type thermoelectric material manufactured by a manufacturing method for a BiTe-based n-type thermoelectric material according to one embodiment.

[0072] Referring to FIG. 1, a method for manufacturing a BiTe-based n-type thermoelectric material according to an embodiment includes the steps of: x Sb 2-x To produce an n-type thermoelectric material, an n-type powder material (Bi) containing crystal grains with a composition of Te3 (where x is 1.0≦x≦1.9) but with a large amount of Te vacancy defects was used. 1.7 Sb 0.3 The process includes the step of producing Te3(n-BST) powders.

[0073] Here, the n-type powder material is approximately -1 × 10 19 cm -3 or more, preferably -2 to -10 × 10 19 cm -3 The density of charge (n) or approximately 120 cm 2 / V·s or more, preferably about 120 to 280 cm 2 It can have a charge mobility (μ) of 1 / V·s.

[0074] For this purpose, the process for producing the n-type powder material includes: Bi, Sb, Te and compounds containing one or more of these x Sb 2-x Te3 (wherein x is 1.0≦x≦1.9), and then vacuum-sealing the mixture; The step may include crushing the vacuum sealed mixture or an ingot of the mixture to form a powder.

[0075] Next, a manufacturing method of a powder for manufacturing a BiTe-based n-type thermoelectric material according to one embodiment includes the steps of mixing the n-type powder material and an excess amount of Te material, forming a compact, and then performing a melt spinning process on the compact to form a film-shaped powder.

[0076] Referring to FIG. 1, the Bi x Sb 2-x A film-shaped (or ribbon-shaped) powder (Melt spun [Bi]) having a morphology containing an excess amount of Te between crystal grains with a composition of Te3 (where x is 1.0≦x≦1.9) was prepared. 1.7 Sb 0.3 Te3(n-BST)+Te]Ribbon-type Powders (MS) can be formed.

[0077] For this purpose, the mixed powder of the n-type powder material and an excess amount of Te material can be molded by a pressure molding method, and the molded body can be melted in a chamber with an inert atmosphere and then sprayed onto a roller rotating at 30 to 100 m / s. Through this process, Bi, Sb, and Te are mixed to form Bi. x Sb 2-x A film-shaped (or ribbon-shaped) powder (MS) can be formed having a morphology containing an excess amount of Te between crystal grains having a composition of Te3 (where x is 1.0≦x≦1.9).

[0078] Here, the mixing of the powder material and the excess amount of Te material may be 5 to 30 wt % of Te material, 10 to 30 wt %, or 20 to 30 wt % of Te material, based on the total weight of the mixture of the powder material and the excess amount of Te material.

[0079] Next, a manufacturing method of a BiTe-based n-type thermoelectric material according to one embodiment includes a step of pulverizing the film-shaped powder, and then performing a spark plasma sintering process to form the BiTe-based n-type thermoelectric material.

[0080] This process induces a large stress in the manufactured n-type thermoelectric material, adjusts atomic defects, and forms a dislocation network, resulting in a BiTe-based n-type thermoelectric material (Bulk Bi 1.7 Sb 0.3 Te3(n-BST) with Dislocations and Te Bi、Sb ) may be a process for producing the

[0081] The spark plasma sintering step in the above process can be carried out at a temperature of 450°C to 550°C, preferably 470°C to 490°C, at a pressure of 30 to 80 MPa, preferably 40 to 60 MPa, for 3 to 15 minutes, preferably 4 to 8 minutes.

[0082] By performing spark plasma sintering under the above conditions, it is possible to further increase the electrical conductivity and simultaneously further reduce the thermal conductivity.

[0083] In one embodiment, a method for manufacturing a BiTe-based n-type thermoelectric material is to increase the number of Te vacancy defects by performing the spark plasma sintering process, to form a dislocation network having a net structure in which a plurality of dislocations are connected to each other, and to further reduce antisite defects (Te Bi ) and antisite defects formed by Te substitution at the Sb site (Te Sb ), it is possible to produce a BiTe-based n-type thermoelectric material with improved electrical conductivity and lower thermal conductivity, ultimately resulting in significantly improved thermoelectric performance.

[0084] FIG. 2A is a schematic diagram of a unit cell of a Bi-Sb-Te material, and FIGS. 2B and 2C are first-principles calculation results to identify atomic defects formed in Bi-Sb-Te. 0.3 Sb 1.7This is a graph comparing the formation energies of various atomic defects formed when compressive deformation is applied to the thermodynamically minimum Te content (Te-poor) in the composition of Te3, calculated according to the Fermi level. Figure 2C shows the formation energies of various atomic defects formed when compressive deformation is applied to the Te content (Te-poor) in the composition of Bi3. 0.3 Sb 1.7 This is a graph comparing the formation energies of various atomic defects that are formed when compressive deformation is applied to a Te3 composition with the maximum thermodynamically allowable amount of Te (Te-rich), calculated according to the Fermi level.

[0085] Referring to Figure 2B, when Te is insufficient, it can be seen that the formation of antisite defects where Te vacancies are filled with Sb is the most energetically stable, and holes can be generated here. Also, referring to Figure 2C, it can be seen that the formation of antisite defects where Bi vacancies are filled with Te is the most energetically stable, and electrons can be generated here.

[0086] Furthermore, referring to FIG. 2C, when Te is added in excess, Te is substituted for Bi sites to form antisite defects (Te Bi ) and antisite defects formed by Te substitution at the Sb site (Te Sb ) is low, which indicates that the formation energy of Te Bi and Te Sb can be formed.

[0087] Furthermore, the increase in the amount of Te vacancy defects during the process can be confirmed through the following Experimental Example 1 and FIGS. 4A to 4D, and the formation of the dislocation network can be confirmed through FIGS. 9A to 9D, 10A, and 10B.

[0088] In another aspect, A thermoelectric element is provided that includes the BiTe-based n-type thermoelectric material.

[0089] The thermoelectric element may be a thermoelectric power generating element or a thermoelectric cooling / heating element.

[0090] Example A: Powder production for BiTe-based n-type thermoelectric materials Step 1: Bi, Sb, and Te are reacted with Bi 1.7 Sb 0.3 Te 3.0 After that, the mixture was weighed and mixed to match the composition of 2 × 10 -5 The tube was then placed in a stirring furnace and stirred at 750°C for 2 hours at a rate of 10 rpm, followed by furnace cooling to form an ingot. The ingot was then milled for 10 hours using a high-energy ball milling machine to produce an n-type powder material (initial state) containing a large amount of Te vacancy defects.

[0091] Step 2: The n-type powder material was mixed with Te material at a concentration of 25 wt% of the total mixed powder, and then pressed at 10 MPa to form a pellet. The pellet was then placed in a quartz tube equipped with a heated nozzle and installed in a melt spinning apparatus. The inner chamber of the quartz tube was then filled with Ar (0.04 MPa) to prevent oxidation during melting. The ingot was then melted using the heated nozzle, and the melt was discharged onto a copper roller rotating at a linear speed of 45 m / s under an Ar pressure pulse of 40 kPa. This rapid solidification process produced a film-shaped (ribbon-shaped) powder (MS).

[0092] <Example B-1> Production of BiTe-based n-type thermoelectric material (Te 25%) (1) 1 is a flowchart showing a process for producing a BiTe-based n-type thermoelectric material according to one embodiment. Referring to FIG. 1, a BiTe-based n-type thermoelectric material was produced by the following method.

[0093] Step 1: Bi, Sb, and Te are reacted with Bi 1.7 Sb 0.3 Te 3.0 After that, the mixture was weighed and mixed to match the composition of 2 × 10 -5The tube was then placed in a stirring furnace and stirred at 750°C for 2 hours at a rate of 10 rpm, followed by furnace cooling to form an ingot. The ingot was then milled for 10 hours using a high-energy ball milling machine to produce an n-type powder material (initial state) containing a large number of Te vacancies.

[0094] Step 2: The n-type powder material was mixed with Te material at a concentration of 25 wt% of the total mixed powder, and then pressed at 10 MPa to form a pellet. The pellet was then placed in a quartz tube equipped with a heated nozzle and installed in a melt spinning apparatus. The inner chamber of the quartz tube was then filled with Ar (0.04 MPa) to prevent oxidation during ingot melting. The ingot was then melted using the heated nozzle, and the melt was discharged onto a copper roller rotating at a linear speed of 45 m / s under an Ar pressure pulse of 40 kPa. This rapid solidification process resulted in the formation of a film-shaped (ribbon-shaped) powder (MS).

[0095] Step 3: The melt-spun film-shaped powder is pulverized into fine powder, and then subjected to spark plasma sintering (SPS) at 480°C and 50 MPa for 5 minutes to obtain a condensed bulk (wafer-shaped) BiTe-based n-type thermoelectric material (Bi 1.7 Sb 0.3 Te 3.0 +25wt% Te).

[0096] <Example B-2> Production of BiTe-based n-type thermoelectric material (Te 15%) (2) The same method as in Example 1 was carried out, except that in step 2 of Example B-1, the content of the Te powder to be mixed was changed to 15 wt % of the total mixed powder, to obtain a BiTe-based n-type thermoelectric material (Bi 1.7 Sb 0.3 Te 3.0 +15wt% Te).

[0097] <Example B-3> Production of BiTe-based n-type thermoelectric material (3) The same method as in Example 1 was carried out, except that in step 3 of Example B-1, spark plasma sintering (SPS) was carried out at 500°C and 50 MPa for 5 minutes, to prepare a BiTe-based n-type thermoelectric material (Bi 1.7 Sb 0.3 Te 3.0 +15wt% Te).

[0098] <Example B-4> Preparation of BiTe-based n-type thermoelectric material (4) The same method as in Example 1 was carried out, except that in step 3 of Example B-1, spark plasma sintering (SPS) was carried out at 480°C and 50 MPa for 3 minutes, to prepare a BiTe-based n-type thermoelectric material (Bi 1.7 Sb 0.3 Te 3.0 +15wt% Te).

[0099] <Example B-5> Preparation of BiTe-based n-type thermoelectric material (5) The same method as in Example 1 was carried out, except that in step 3 of Example B-1, spark plasma sintering (SPS) was carried out at 480°C and 50 MPa for 10 minutes, to prepare a BiTe-based n-type thermoelectric material (Bi 1.7 Sb 0.3 Te 3.0 +15wt% Te).

[0100] <Comparative Example 1> Step 1: Bi, Sb, and Te are reacted with Bi 1.7 Sb 0.3 Te 3.0 After that, the mixture was weighed and mixed to match the composition of 2 × 10 -5 The tube was then placed in a stirring furnace and stirred at 750°C for 2 hours at a rate of 10 rpm, followed by furnace cooling to form an ingot. The ingot was then milled for 10 hours using a high-energy ball milling machine to produce an n-type powder material containing a large amount of Te vacancy defects.

[0101] Step 2: The n-type powder material was pulverized into fine powder, and then subjected to spark plasma sintering (SPS) at 480°C and 50 MPa for 5 minutes to form a condensed bulk (wafer) BiTe-based n-type thermoelectric material (initial state).

[0102] <Experimental Example 1> Microstructural analysis of powder for manufacturing BiTe-based n-type thermoelectric material To analyze the microstructure of the powder for manufacturing a BiTe-based n-type thermoelectric material manufactured according to one embodiment, the surface and cross section of the powder manufactured in Example A were observed using a scanning electron microscope (SEM), and component analysis was performed using an energy dispersive spectroscopy (EDS). The results are shown in Figures 4A to 4D.

[0103] Figure 4A is a surface photograph of the film-shaped powder produced in Example A, Figure 4B is an enlarged photograph of the boxed area of ​​photo A, Figure 4C is an EDS component analysis photograph of the area of ​​photo B, and Figure 4D is a cross-sectional photograph of the film-shaped powder produced in Example A.

[0104] It can be seen from FIG. 2 that a film-shaped powder having a composition of Bi, Sb, and Te was formed by the method according to one embodiment.

[0105] <Experimental Example 2> Microstructure analysis To analyze the microstructures of the n-type thermoelectric materials prepared in Examples B-1 and B-2 and Comparative Example 1, the surfaces and cross sections of the n-type thermoelectric materials prepared in Examples B-1 and B-2 and Comparative Example 1 were analyzed using a scanning electron microscope (SEM). The results are shown in FIGS. 5A to 5F, and EBSD analysis results are shown in FIGS. 6A to 6F.

[0106] 5A and 5D are cross-sectional and surface photographs, respectively, of the n-type thermoelectric material (initial state) produced in Comparative Example 1, FIGS. 5B and 5E are cross-sectional and surface photographs, respectively, of the n-type thermoelectric material (Te 15%) produced in Example 2, and FIGS. 5C and 5F are cross-sectional and surface photographs, respectively, of the n-type thermoelectric material (Te 25%) produced in Example 1.

[0107] 5A to 5F, it can be seen that a BiTe-based n-type thermoelectric material was formed.

[0108] 6A, 6B, and 6C are the EBSD analysis results of the n-type thermoelectric material (initial state) produced in Comparative Example 1, and FIGS. 6D, 6E, and 6F are the EBSD analysis results of the n-type thermoelectric material (Te 25%) produced in Example 1.

[0109] 6A to 6F, the structure and orientation relationship of the crystal grain boundaries of the BiTe-based n-type thermoelectric material can be confirmed.

[0110] Figure 6A shows the image quality (IQ) map value, which is the clarity of the Kikuchi diffraction pattern of an n-type thermoelectric material (initial state). The results in Figure 6A were used to calculate the average size of the grain boundaries shown in Figure 6C, and it was confirmed that the grain boundaries range in size from 50 nm to 100 μm.

[0111] Figure 6B is an inverse pole figure (IPF) map showing the orientation distribution of the grain boundaries. It can be seen that the grains with various orientations are evenly distributed.

[0112] Figure 6D shows the image quality (IQ) map value, which is the clarity of the Kikuchi diffraction pattern for n-type thermoelectric material (Te 25%). The results in Figure 6D were used to calculate the average size of the grain boundaries shown in Figure 6F, and it was confirmed that the grain boundaries range in size from 1 μm to 100 μm.

[0113] Figure 6E is an inverse pole figure (IPF) map showing the orientation distribution of the grain boundaries. It can be seen that the excess amount of Te caused partial liquid phase sintering, increasing the size of the grain boundaries compared to the n-type thermoelectric material (initial state).

[0114] <Experimental Example 3> Evaluation of thermoelectric properties To confirm the thermoelectric properties of the BiTe-based n-type thermoelectric material manufactured according to one example, the electrical conductivity, charge concentration (n), thermal conductivity, and dimensionless figure of merit (ZT) as a function of temperature were measured for the BiTe-based n-type thermoelectric materials manufactured according to Example B-1 (Te 25%, dislocation controlled) and Comparative Example 1 (initial state), and the results are shown in FIGS. 7A to 7D.

[0115] FIG. 7A shows data comparing electrical conductivities. As shown in FIG. 7A, the BiTe-based n-type thermoelectric material produced in Example B-1 has an electrical conductivity of approximately 27×10 at room temperature of 25° C. 4 It can be seen that the material exhibits significantly superior electrical conductivity of S / m or more, which is more than twice as high as that of the n-type thermoelectric material (initial state) of Comparative Example 1.

[0116] This result can be attributed to the improvement of electron concentration due to the formation of Te vacancy defects and anti-site defects, where Te is substituted at Bi or Sb sites, through the melt spinning process with the addition of an excess amount of Te and the subsequent spark plasma sintering process.

[0117] FIG. 7B shows data comparing the Seebeck coefficients. As shown in FIG. 7B, the BiTe-based n-type thermoelectric material prepared in Example B-1 exhibits Seebeck coefficient values ​​in a similar range from room temperature to 200°C.

[0118] 7C shows data comparing thermal conductivities, and as shown in Fig. 7C, the BiTe-based n-type thermoelectric material produced in Example B-1 has the same or similar thermal conductivity as the n-type thermoelectric material (initial state) of Comparative Example 1 at room temperature of 25°C. However, the thermal conductivity of the n-type thermoelectric material (initial state) of Comparative Example 1 increases with increasing temperature, whereas the BiTe-based n-type thermoelectric material produced in Example B-1 does not increase and maintains a low value. This confirms that the BiTe-based n-type thermoelectric material produced in Example B-1 exhibits lower thermal conductivity in the temperature range from room temperature to 200°C.

[0119] The above results can be attributed to the phonon scattering effect of the dislocation network formed during the melt spinning process with the addition of excess Te and the subsequent spark plasma sintering process.

[0120] FIG. 7D also shows comparative data on dimensionless figure of merit (ZT). As shown in FIG. 7D, the BiTe-based n-type thermoelectric material prepared in Example B-1 exhibits significantly better thermoelectric properties than the thermoelectric material (initial state) prepared in Comparative Example 1 in the temperature range of room temperature to 200°C, and exhibits a maximum dimensionless figure of merit (ZT) of 1.26, which is significantly higher by more than 150% than the n-type powder material (initial state) prepared in Comparative Example 1.

[0121] From the above results, it can be confirmed that the BiTe-based n-type thermoelectric material prepared according to one embodiment can have improved electrical conductivity and low thermal conductivity, and ultimately exhibits excellent thermoelectric properties.

[0122] <Experimental Example 4> Evaluation of charge density and charge mobility To evaluate the charge density and charge mobility of the n-type thermoelectric materials prepared in the Examples and Comparative Examples, the charge density and charge mobility of the n-type thermoelectric materials prepared in Example B-1 and Comparative Example 1 were measured, and the results are shown in FIGS. 8A and 8B.

[0123] As shown in FIGS. 8A and 8B, the charge densities of the n-type thermoelectric materials prepared in Example B-1 and Comparative Example 1 were compared. As a result, it was confirmed that the thermoelectric material of Example B-1 had significantly higher charge density and charge mobility than the thermoelectric material of Comparative Example 1.

[0124] More specifically, the BiTe-based n-type thermoelectric material produced in Example B-1 had a melting point of about 11 ea / 10 19 cm -3 The charge density (n) and the charge density (n) of about 220-260 cm 2 It can be confirmed that the charge mobility (μ) is 1 / V·s.

[0125] From the above results, it can be confirmed that the BiTe-based n-type thermoelectric material according to one embodiment can have a higher charge density and charge mobility by performing melt spinning and spark plasma sintering.

[0126] <Experimental Example 5> Dislocation network analysis In order to confirm the dislocation network formed inside the n-type thermoelectric material produced according to the example, the inside of the n-type thermoelectric material produced in Example B-1 was observed using a transmission electron microscope (TEM), and the results are shown in Figures 9A to 9D, 10A, and 10B.

[0127] FIG. 9A is a TEM photograph of the inside of the n-type thermoelectric material produced in Example B-1, FIG. 9B is a TEM photograph of the boxed portion of FIG. 9A taken in "two beam dark field image" mode for detailed observation of the dislocation network, FIG. 9C is a TEM photograph of another portion of the inside of the thermoelectric material, FIG. 9D is a TEM photograph of the interface between two crystal grains in FIG. 9C taken in "two beam dark field image" mode for detailed observation of the dislocation network, and FIG. 9E is a photograph of a dislocation network observed to be geometrically different depending on the TEM vector.

[0128] These results confirm that a dislocation network with a net structure is formed in which multiple dislocations are interconnected between crystal grains and between crystal grains, forming hexagonal voids or interconnected in a zigzag pattern. Similar to the crystal structure diagrams shown in Figures 9C and 9D, it can also be seen that the (015), (225), and (210) planes form a geometric structure to form a dislocation network.

[0129] FIG. 10A is a TEM photograph showing crystal grains, and FIG. 10B is a STEM photograph showing dislocation network arrays present between crystal grains. As shown in FIGS. 10A and 10B, it can be seen that dislocation networks are interconnected between crystal grains in the thermoelectric material to form arrays.

[0130] <Experimental Example 6> Evaluation of thermoelectric properties depending on Te content In accordance with one embodiment, a BiTe-based n-type thermoelectric material was manufactured. In order to confirm the thermoelectric properties depending on the added Te content, the dimensionless figure of merit (ZT) as a function of temperature was measured for the BiTe-based n-type thermoelectric materials manufactured in Example B-1 (Te 25%), Example B-2 (Te 15%), and Comparative Example 1 (initial state). The results are shown in FIG. 11.

[0131] As shown in FIG. 11, the dimensionless figure of merit (ZT) of the BiTe-based n-type thermoelectric materials manufactured in Example B-1 (Te 25%), Example B-2 (Te 15%), and Comparative Example 1 (initial state) was compared. As a result, it was confirmed that Example B-1, in which 25 wt % Te was added, exhibited a particularly superior figure of merit (ZT).

Claims

1. Bi ｘ Sb ２－ｘ Te ３ (wherein x is 1.0≦x≦1.9), and Te is filled between the crystal grains.

2. The BiTe-based polycrystalline powder is Bi ｘ Sb ２－ｘ Te ３ 2. The powder for producing a BiTe-based n-type thermoelectric material according to claim 1, comprising crystal grains having a composition: (wherein x is 1.5≦x≦1.9).

3. The powder for producing a BiTe-based n-type thermoelectric material according to claim 1 is produced by spark plasma sintering, ｘ Sb ２－ｘ Te ３ A BiTe-based n-type thermoelectric material comprising crystal grains having a composition of the formula: (wherein x is 1.0≦x≦1.9), and having atomic defects and line defects.

4. The BiTe-based polycrystalline n-type thermoelectric material is 4. The BiTe-based n-type thermoelectric material according to claim 3, comprising anti-site defects and a dislocation network formed in grains or grain boundaries.

5. 5. The BiTe-based n-type thermoelectric material according to claim 4, wherein the anti-site defect is located at a Bi or Sb site by substitution of Te.

6. 5. The BiTe-based n-type thermoelectric material according to claim 4, wherein the dislocation network has a net structure in which a plurality of dislocations are interconnected.

7. 4. The BiTe-based n-type thermoelectric material according to claim 3, which exhibits n-type thermoelectric properties at room temperature to 300°C.

8. The BiTe-based n-type thermoelectric material is 20 x 10 at room temperature ４ S / m ~ 30 x 10 ４ The BiTe-based n-type thermoelectric material according to claim 3 , which exhibits an electrical conductivity of S / m.

9. Bi ｘ Sb ２－ｘ Te ３ producing a polycrystalline n-type powder material comprising crystal grains having a composition of:

2. A method for producing a powder for producing a BiTe-based n-type thermoelectric material, comprising the steps of: mixing the n-type powder material and an excess amount of Te material, forming a compact, and then performing a melt-spinning process on the compact, thereby forming the powder for producing a BiTe-based n-type thermoelectric material according to claim 1.

10. Bi ｘ Sb ２－ｘ Te ３ producing an n-type powder material comprising crystal grains having a composition of: a step of forming a compact by mixing the n-type powder material and an excess amount of Te powder, and then subjecting the compact to a melt spinning process to form a film-shaped powder; A method for producing a BiTe-based n-type thermoelectric material, comprising the step of pulverizing the film-shaped powder and then performing a spark plasma sintering process to form the BiTe-based n-type thermoelectric material according to claim 2.

11. The step of producing the n-type powder material comprises: Bi, Sb, Te and compounds containing one or more of these are ｘ Sb ２－ｘ Te ３ (wherein x is 1.0≦x≦1.9), and then vacuum sealing the mixture; The method for producing a BiTe-based n-type thermoelectric material according to claim 10, comprising crushing the vacuum-sealed mixture or an ingot of the mixture to form a powder.

12. 10. The method for producing a BiTe-based n-type thermoelectric material according to claim 9, wherein the mixing of the powder material and the excess amount of Te material comprises mixing 5 to 30 wt % of the Te material with respect to the total weight of the mixture of the powder material and the excess amount of Te material.

13. A thermoelectric element comprising the BiTe-based n-type thermoelectric material according to claim 3 .

14. The thermoelectric element of claim 13 , wherein the thermoelectric element is a thermoelectric power generating element or a thermoelectric cooling / heating element.

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