KR102510159B1 - Thermoelectric Permingeatite Doped with 13 Group Elements and Its Solid-State Synthesis Process - Google Patents

Abstract

The present invention relates to a firming geartite thermoelectric material to which a group 13 element is added and a solid-state synthesis process thereof, and more particularly, to a firming geartite thermoelectric material doped with aluminum (Al) or indium (In) capable of improving thermoelectric performance. and a manufacturing method thereof. The manufacturing method of the present invention can effectively manufacture a permingeatite thermoelectric material doped with aluminum (Al) or indium (In) under optimal process conditions by using a mechanical alloying method and a hot compression process. In the case of the modified fermingeartite thermoelectric material, the thermoelectric performance is remarkably improved.

Description

Permingeatite thermoelectric material with group 13 elements added and its solid-state synthesis process

The present invention relates to a firming geartite thermoelectric material to which a group 13 element is added and a solid-state synthesis process thereof, and more particularly, to a firming geartite thermoelectric material doped with aluminum (Al) or indium (In) capable of improving thermoelectric performance. and a manufacturing method thereof.

In the 21st century, the preservation of the global environment and the depletion of energy resources have emerged, requiring the development of alternative energy sources. Thermoelectric energy conversion technology is attracting attention as an alternative energy technology because it can directly convert thermal energy into electrical energy or electrical energy into thermal energy. Thermoelectric materials are eco-friendly energy conversion materials that can obtain electrical energy by utilizing abandoned or neglected thermal energy such as automobile and industrial waste heat and solar heat, and do not cause pollution such as noise, vibration, and waste.

Thermoelectric conversion technology can be classified into thermoelectric cooling technology and thermoelectric power generation technology. Thermoelectric cooling technology has the advantage of being able to replace refrigerant gas that causes global warming, eliminating vibration and noise as it does not require a compressor, and enabling precise temperature control. On the other hand, thermoelectric power generation technology is the only power generation method that can directly convert low-temperature thermal energy and small-scale distributed thermal energy that are difficult to recycle into electrical energy. has the advantage of

Energy conversion efficiency of thermoelectric materials is evaluated by a dimensionless figure of merit ( ZT ), which is defined as ZT = α ² σκ ^-1 T . where α, σ, κ, and T are the Seebeck coefficient, electrical conductivity, thermal conductivity, and absolute temperature, respectively. The Seebeck coefficient is defined as the change in electromotive force per unit temperature difference, and the product of the square of the Seebeck coefficient and the electrical conductivity is called the output factor (α ² σ). Therefore, in order to obtain a thermoelectric material having high performance, a high power factor and low thermal conductivity are required.

에 속해 있다. Cu₃SbSe₄은 ZnSe보다 unit cell당 구성하는 원자수가 4배로 더 많으며, 결정구조는 three-dimensional framework Cu-Se 결합을 하고 있는 CuSe4 tetrahedrons과 one-dimensional array Sb-Se 결합을 하고 있는 SbSe4 tetrahedrons으로 이루어져 있다. Sb-Se 결합길이가 Cu-Se 결합길이보다 크며, CuⅠ-Se 결합길이와 CuⅡ-Se 결합길이도 다르기 때문에 이러한 결합길이의 차이는 전자이동과 포논 산란의 이방성을 증가시켜, 전기적 특성과 열적 특성에 영향을 준다고 보고되었다. Cu₃SbSe₄는 narrow direct band gap(0.13-0.42 eV)과 large carrier effective mass(~1.1 m0)때문에 주목을 받고 있는 열전재료이다. 그러나 Cu₃SbSe₄의 단점은 높은 전기적 비저항과 높은 열전도도를 갖고 있기 때문에 전기 전도도를 향상시키고 열전도도를 감소시킬 필요성이 있다.Recently, researchers are increasingly interested in eco-friendly and economical thermoelectric materials composed of non-toxic, earth-abundant elements. Among them, Cu-Sb-Se ternary chalcogenides are attracting attention. Permingeatite (Cu ₃ SbSe ₄ ) is a space group derived from a zinc-blende structure.

belongs to Cu ₃ SbSe ₄ has 4 times more atoms per unit cell than ZnSe, and its crystal structure consists of three-dimensional framework Cu-Se bonded CuSe4 tetrahedrons and one-dimensional array Sb-Se bonded SbSe4 tetrahedrons. consist of. Since the Sb-Se bond length is larger than the Cu-Se bond length, and the CuI-Se bond length and CuII-Se bond length are also different, the difference in bond length increases the anisotropy of electron transfer and phonon scattering, resulting in electrical and thermal properties. has been reported to affect Cu ₃ SbSe ₄ is a thermoelectric material that has attracted attention because of its narrow direct band gap (0.13–0.42 eV) and large carrier effective mass (~1.1 m0). However, since Cu ₃ SbSe ₄ has a high electrical resistivity and high thermal conductivity, it is necessary to improve the electrical conductivity and reduce the thermal conductivity.

Therefore, in the present invention, in order to improve the performance of the Permingeatite (Cu ₃ SbSe ₄ ) thermoelectric material, the mechanical alloying method, which is a high-energy ball mill process at room temperature, and the hot compression process are used to obtain the 15th group (B ^V ) Cu ₃ Sb _1-y (Al/In) _y Se ₄ thermoelectric material doped with aluminum (Al) or imdium (In), a group 13 (B ^Ⅲ ) element, in place of element Sb, and as a result, Cu ₃ Compared to SbSe ₄ thermoelectric materials The present invention was completed by confirming the effect of greatly improving the thermoelectric performance.

Korean Patent Registration No. 10-1470197

Accordingly, an object of the present invention is to provide a method for manufacturing a firmingeartite thermoelectric material doped with aluminum (Al) or indium (In).

Another object of the present invention is to provide a firmingeartite thermoelectric material doped with aluminum (Al) or indium (In) manufactured by the above method.

In order to achieve the object of the present invention as described above,

The present invention comprises (a) mixing doping element powder aluminum (Al) or indium (In) with Cu, Sb and Se as raw materials; (b) mechanically alloying the powders mixed in step (a); and (c) hot pressing the alloyed powder through step (b).

In one embodiment of the present invention, when the doping element is aluminum (Al), in step (a), the Cu, Sb, Se, and Al powders are Cu ₃ Sb _1-y Al _y Se ₄ (0 < y < 1) It can be mixed according to the stoichiometric composition of

In one embodiment of the present invention, when the doping element is indium (In), in step (a), the Cu, Sb, Se, and In powders are Cu ₃ Sb _1-y In _y Se ₄ (0 < y < 1) It can be mixed according to the stoichiometric composition of

In one embodiment of the present invention, when the doping element is aluminum (Al), in step (a), the Cu, Sb, Se, and Al powders have a chemistry of Cu ₃ Sb _1-y Al _y Se ₄ (y = 0.04) It can be mixed according to the stoichiometric composition.

In one embodiment of the present invention, when the doping element is indium (In), in step (a), the Cu, Sb, Se, and In powders have a chemistry of Cu ₃ Sb _1-y In _y Se ₄ (y = 0.04) It can be mixed according to the stoichiometric composition.

In one embodiment of the present invention, step (b) may be mechanically alloyed through a process of ball milling the powder mixed in step (a) at 200 rpm to 600 rpm for 1 hour to 48 hours.

In one embodiment of the present invention, the hot compression in step (c) may be performed for 1 to 3 hours in a temperature range of 400 to 800K and a pressure range of 10 to 200MPa.

In addition, the present invention provides a firmingeartite thermoelectric material doped with aluminum (Al) or indium (In) manufactured by the above method.

In one embodiment of the present invention, the composition of the thermoelectric material may be Cu ₃ Sb _0.96 Al _0.04 Se ₄ or Cu ₃ Sb _0.96 In _0.04 Se ₄ .

In one embodiment of the present invention, the thermoelectric material may have an output factor of 0.5 to 0.7 mWm ^-1 K ^-2 and a thermal conductivity of 0.7 to 0.9 Wm ^-1 K ^-1 at a temperature of 500 to 650K.

The manufacturing method of the present invention can effectively manufacture a permingeatite thermoelectric material doped with aluminum (Al) or indium (In) under optimal process conditions by using a mechanical alloying method and a hot compression process. In the case of the modified fermingeartite thermoelectric material, the thermoelectric performance is remarkably improved.

1 is an X-ray diffraction analysis result of a powder Cu ₃ Sb _1-y B ^Ⅲ _y Se ₄ specimen synthesized by mechanical alloying according to the present embodiment.
2 is an X-ray diffraction analysis result of a Cu ₃ Sb _1-y B ^Ⅲ _y Se ₄ specimen sintered by hot compression molding according to the present embodiment.
3 shows a BSE-SEM image, elemental line scans, and maps of a Cu ₃ Sb _1-y B ^Ⅲ _y Se ₄ specimen prepared according to the present embodiment.
4 shows the carrier concentration and mobility of the Cu ₃ Sb _1-y B ^Ⅲ _y Se ₄ specimen prepared according to the present embodiment.
5 shows the electrical conductivity of the Cu ₃ Sb _1-y B ^Ⅲ _y Se ₄ specimen prepared according to the present embodiment.
6 shows the Seebeck coefficient of the Cu ₃ Sb _1-y B ^Ⅲ _y Se ₄ specimen prepared according to the present embodiment.
7 shows output factors of the Cu ₃ Sb _1-y B ^Ⅲ _y Se ₄ specimen prepared according to the present embodiment.
8 shows the thermal conductivity (к), lattice thermal conductivity (к _L ), and electronic thermal conductivity (к _E ) of the Cu ₃ Sb _1-y B ^Ⅲ _y Se ₄ specimen prepared according to the present embodiment (8a: Total thermal conductivity, 8b: lattice thermal conductivity, 8c: electronic thermal conductivity).
9 shows the dimensionless thermoelectric figure of merit (ZT) of the Cu ₃ Sb _1-y B ^Ⅲ _y Se ₄ specimen prepared according to the present embodiment.

An embodiment according to the present invention will be described in detail with reference to the accompanying drawings.

The present invention comprises (a) mixing doping element powder aluminum (Al) or indium (In) with raw materials Cu, Sb and Se; (b) mechanically alloying the powder mixed in step (a); ; and (c) hot pressing the alloyed powder through step (b).

The step (a) of the present invention is a step of mixing raw material Cu, Sb, S, and Al (or In) elemental powder, wherein the elemental powder is Cu ₃ Sb _1-y Al _y Se ₄ (0 < y < 1) or Cu ₃ Sb _1-y In _y Se ₄ (0 < y < 1) may be mixed according to the stoichiometric composition, and preferably the element powder is Cu ₃ Sb _1-y Al _y Se ₄ (y = 0.04) or Cu ₃ Sb _1-y In _y Se ₄ (y = 0.04).

In an embodiment of the present invention, aluminum (Al) or indium (In) doped fermingite Cu ₃ Sb _1-y Al _y Se ₄ (y = 0.02, 0.04, 0.06, 0.08) and Cu ₃ Sb _1-y In Cu (purity 99.9%, <45 μm, Kojundo) _, Sb (purity 99.999%, <150 μm, Kojundo), Se (purity 99.9 _% , <10 μm, Kojundo), Al (purity 99.9%, <106 μm, Kojundo), and In (purity 99.99%, <75 μm, Kojundo) were used.

The step (b) of the present invention is a step of mechanically alloying the powders mixed in the step (a), mechanically alloying the powders mixed according to the stoichiometric composition by a ball-mill method to Cu ₃ Sb _1-y Al _y Se ₄ (0 < y < 1) or Cu ₃ Sb _1-y In _y Se ₄ (0 < y < 1) powders can be synthesized.

In step (b), the ball-mill method may be performed at 200 rpm to 600 rpm for 1 hour to 48 hours.

In an embodiment of the present invention, 20 g of the raw material powder weighed according to the stoichiometric composition and 400 g of a stainless steel ball having a diameter of 5 mm are placed in a hardened steel jar, and after evacuating the inside of the steel jar, argon (Ar) Gas was injected and mechanical alloying (hereinafter referred to as 'MA') was performed using a planetary ball mill (Fritsch, Pulverisette 5) at a rotation speed of 350 rpm for 12 hours.

Step (c) of the present invention is a step of hot pressing the alloyed powder through step (b), by hot pressing and sintering the alloyed powder to obtain Cu ₃ Sb _1-y Al _y Se ₄ (0 < y < 1) or Cu ₃ Sb _1-y In _y Se ₄ (0 < y < 1) thermoelectric materials can be manufactured.

Step (c) may be performed for 1 to 3 hours in a temperature range of 400 to 800K and a pressure range of 10 to 200MPa. When hot compression is performed at a temperature lower than the above range, at a low atmospheric pressure and for a short time, it is difficult to form a desired density, and when hot compression is performed at a temperature higher than the above range, at a high atmospheric pressure and for a long time, a second phase is formed or chalcogen is formed. A problem of volatilization of the element may occur.

In an embodiment of the present invention, the alloyed powder was loaded into a graphite mold having an inner diameter of 10 mm and subjected to vacuum hot pressing (hereinafter referred to as 'HP') at 573 K for 2 hours at a pressure of 70 MPa.

Various physical properties were measured for the specimens prepared by the above process.

First, the image of the sintered specimen cut into a disc shape with a size of 1 mm (thickness) x 10 mm (diameter) through an X-ray diffractometer (Bruker, D8-Advance) using Cu Kα (40 kV, 30 mA) radiation was analyzed. With 0.02° step, the diffraction angle was measured as 2θ = 10-90°. Rietveld refinement was performed with the TOPAS program to calculate the lattice constant of the sintered body. The cross-sectional microstructure of the specimen was observed using the back electron scattering (BSE mode) technique of a scanning electron microscope (FEI, Quanta400). Elemental line scans and maps were analyzed according to the energy level of each element with an energy dispersive X-ray spectrometer (EDS; Bruker, XFlash4010). Using the Van der Pauw method (Keithley 7065), the carrier concentration and mobility were evaluated by measuring the Hall coefficient under the conditions of a magnetic field of 1 T and a current of 100 mA. In order to measure the Seebeck coefficient and electrical conductivity using ZEM-3 (Ulvac-Riko), specimens were cut into rectangular pillars with a size of 3 mm x 3 mm x 9 mm and measured in a He atmosphere. Using the TC-9000H (Ulvac-Riko), the sintered specimen was cut into a disc shape with a size of 1 mm (thickness) x 10 mm (diameter), and thermal diffusivity, specific heat, and density were measured and evaluated in a vacuum atmosphere by the laser flash method. . The temperature dependence of thermoelectric properties was evaluated in the temperature range of 323-623K from the measured Seebeck coefficient, electrical conductivity and thermal conductivity.

1 shows an X-ray diffraction pattern of a powder Cu ₃ Sb _1-y B ^Ⅲ _y Se ₄ specimen synthesized by mechanical alloying. The diffraction peaks of all specimens showed a single phase with a tetragonal structure, consistent with the standard diffraction pattern for firmingeartite (ICDD PDF# 01-085-0003).

2 shows an X-ray diffraction pattern of Cu ₃ Sb _1-y B ^Ⅲ _y Se ₄ sintered by hot compression molding. A single phase of tetragonal structure synthesized by mechanical alloying was maintained after vacuum hot compression molding at 573 K, and phase change and secondary phase were not detected. Reitveld analysis was performed to find out the change in lattice constant due to doping (substitution) of aluminum (Al) and indium (In) elements. The calculated lattice constants are summarized in Table 1. Doping with aluminum (Al) changed the a-axis lattice constant from 0.5649 nm to 0.5652-0.5653 nm and the c-axis lattice constant from 1.1247 nm to 1.1249-1.1251 nm. In addition, doping with indium (In) increased the a-axis lattice constant to 0.5653-0.5654 nm and the c-axis lattice constant to 1.1253-1.1254 nm. This means that aluminum (Al) and indium (In) were successfully substituted at the Sb site, and the change in lattice constant according to the change in doping amount was not large.

Relative density, lattice constant and Lorentz number of Cu ₃ Sb _1-y (Al/In) _y Se ₄ Specimen Relative Density
[%] Lattice Constant [nm] Lorenz Number
[10 ^-8 V ² K ^-2 ] a-axis c-axis Cu ₃ SbSe ₄ 98.1 0.5649 1.1247 1.5712 Cu ₃ Sb _0.98 Al _0.02 Se ₄ 98.0 0.5653 1.1250 1.8150 Cu ₃ Sb _0.96 Al _0.04 Se ₄ 97.6 0.5652 1.1249 1.5773 Cu ₃ Sb _0.94 Al _0.06 Se ₄ 97.5 0.5653 1.1250 1.7628 Cu ₃ Sb _0.92 Al _0.08 Se ₄ 97.8 0.5653 1.1251 1.7697 Cu ₃ Sb _0.98 In _0.02 Se ₄ 99.2 0.5654 1.1253 1.2003 Cu ₃ Sb _0.96 In _0.04 Se ₄ 98.8 0.5653 1.1253 1.7107 Cu ₃ Sb _0.94 In _0.06 Se ₄ 98.2 0.5653 1.1253 1.7428 Cu ₃ Sb _0.92 In _0.08 Se ₄ 98.6 0.5653 1.1254 1.7757

3 shows BSE-SEM images, elemental line scans, and maps of Cu ₃ Sb _1-y B ^Ⅲ _y Se ₄ . As shown in Table 1, a dense microstructure without pores and cracks was observed, and no secondary phase other than the firming geartite phase was observed. This was consistent with the results of XRD image analysis in FIG. 2 . As a result of EDS elemental analysis, all elements were uniformly distributed.

4 shows charge transfer characteristics of Cu ₃ Sb _1-y B ^Ⅲ _y Se ₄ . Both undoped and Al/In-doped specimens showed positive Hall coefficients and showed p-type conduction characteristics in which majority carriers were holes. The carrier concentration of undoped Cu ₃ SbSe ₄ was 5.2 × 10 ¹⁸ cm ^-3 , and the mobility was 49.9 cm ² V ^-1 s ^-1 . The carrier concentration tended to increase as the doping contents of aluminum (Al) and indium (In) increased. At y = 0.08, Al-doped permingeatite showed a carrier concentration of 8.2 x 10 ¹⁸ cm ^-3 and in-doped permingeatite showed a carrier concentration of 9.2 x 10 ¹⁸ cm ^-3 . In this study, the mobility tended to increase slightly as the carrier concentration increased. This indicates a change within the Hall coefficient measurement error range, as shown in FIG. 4, and is determined to be due to a transition from a non-degenerate semiconductor to a degenerate semiconductor due to aluminum (Al) and indium (In) doping.

5 shows the temperature dependence of the electrical conductivity of Cu ₃ Sb _1-y B ^Ⅲ _y Se ₄ . In the case of undoped and Al-doped permingeatite, the electrical conductivity increased slightly with increasing temperature. However, in the case of in-doped permingeatite, it showed degenerate semiconductor behavior with little temperature dependence. Electrical conductivity increased as the doping content of aluminum (Al) and indium (In) increased at a constant temperature. In the case of doping with indium (In), the electrical conductivity was higher than that of the specimen doped with aluminum (Al), which is because the carrier concentration and mobility are high, as shown in FIG. 4 . When Al ³⁺ or In ³⁺ is substituted for the Sb ⁵⁺ site of Cu ₃ SbSe ₄ , a carrier (hole) is additionally generated, resulting in an increase in electrical conductivity. Cu ₃ Sb _0.92 In _0.08 Se ₄ showed the highest electrical conductivity of (1.4-1.1) × 10 ⁴ Sm ^-1 at 323-623 K.

6 shows the temperature dependence of the Seebeck coefficient of Cu ₃ Sb _1-y B ^Ⅲ _y Se ₄ . Since they are all positive values, it shows p-type semiconductor characteristics, and it was confirmed that the main carrier is a hole. As the doping content of aluminum (Al) and indium (In) increased at a constant temperature, the carrier concentration increased and the Seebeck coefficient decreased. As the temperature increased, the Seebeck coefficient increased, but in the case of Cu ₃ SbSe ₄ and Cu ₃ Sb _0.96 Al _0.04 Se ₄ it decreased at about 500 K or higher. This is the result of an intrinsic transition. The Seebeck coefficient of Cu ₃ Sb _0.96 Al _0.04 Se ₄ had a maximum value of 326 μVK ^-1 at 473 K and then decreased to 304 μVK ^-1 at 623 K as the temperature increased. The reason why the Seebeck coefficient decreases above a certain temperature is because the concentration of electrons, which are thermally active minority carriers from the valence band, increases.

7 shows the temperature dependence of the output factor of Cu ₃ Sb _1-y B ^Ⅲ _y Se ₄ . The output factor (PF = α2σ) is proportional to the Seebeck coefficient (α) and the electrical conductivity (σ), and is a factor related to the output power of the thermoelectric generator. The output factor of Cu ₃ SbSe ₄ was 0.39-0.49 mWm ^-1 K ^-2 at 323-623 K, and the temperature dependence was relatively small. As a result of doping with aluminum (Al) and indium (In), the output factor increased rapidly as the temperature increased. In addition, in the case of indium (In) doped specimens, the output factor was improved at high temperatures. At 623 K, Cu ₃ SbSe ₄ showed 0.49 mWm ^-1 K ^-2 and Cu ₃ Sb _0.96 Al _0.04 Se ₄ showed 0.51 mWm ^-1 K ^-2 , but Cu ₃ Sb _0.96 In _0.04 Se ₄ showed 0.66 mWm ^-1 K It showed a maximum output factor of ^-2 .

8 shows thermal conductivity (к), lattice thermal conductivity (кL), and electronic thermal conductivity (кE) of Cu ₃ Sb _1-y B ^Ⅲ _y Se ₄ . Thermal conductivity is determined by thermal conductivity by phonons and thermal conductivity by carriers. 8a shows the temperature dependence of thermal conductivity. At 323–623 K, the thermal conductivity tended to decrease with increasing temperature. Cu ₃ Sb _0.96 Al _0.04 Se ₄ showed the minimum thermal conductivity value of 0.74 Wm ^-1 K ^-1 at 623 K, and Cu ₃ Sb _0.96 In _0.04 Se ₄ showed the minimum thermal conductivity value of 0.84 Wm ^-1 K ^-1 at 523 K. However, as the aluminum (Al) and indium (In) doping content increased at a constant temperature, the thermal conductivity increased. Figure 8b shows the lattice thermal conductivity. It was found that the lattice thermal conductivity was dominant in the thermal conductivity of firmingeartite. The decrease in lattice thermal conductivity due to the Sb site substitution of aluminum (Al) and indium (In) was not significant. Cu ₃ SbSe ₄ exhibited lattice thermal conductivities of 1.17–0.72 W m ⁻¹ K ⁻¹ at 323–623 K. Cu ₃ Sb _0.96 Al _0.04 Se ₄ showed a minimum lattice thermal conductivity of 0.69 Wm ⁻¹ K ⁻¹ at 623 K, and Cu ₃ Sb _0.96 In _0.04 Se ₄ 0.76 Wm ⁻¹ K ⁻¹ at 523 K. Figure 8c shows the lattice thermal conductivity and electronic thermal conductivity separated by the Wiedemann-Franz law (κE = LσT). where L is the temperature dependent Lorenz number and T is the absolute temperature. The lattice thermal conductivity showed a negative temperature dependence, but the electronic thermal conductivity showed a positive temperature dependence. The electronic thermal conductivity of Cu ₃ SbSe ₄ was 0.02-0.04 W m ^-1 K ^-1 at 323-623 K. The carrier concentration is increased by aluminum (Al) and indium (In) doping, and at 623 K, Cu ₃ Sb _0.92 Al _0.08 Se ₄ is 0.09 Wm ^-1 K ^-1 and Cu ₃ Sb _0.92 In _0.08 Se ₄ is 0.11 Wm ^-1 The electronic thermal conductivity value of K ^-1 is shown.

9 shows the dimensionless figure of merit (ZT) of Cu ₃ Sb _1-y B ^Ⅲ _y Se ₄ . ZT increased with increasing temperature, and Cu ₃ SbSe ₄ showed the maximum ZT = 0.39 at 623 K. Cu ₃ Sb _0.96 Al _0.04 Se ₄ ZT = 0.42 at 623 K, Cu ₃ Sb _0.96 In _0.04 Se ₄ slightly increased ZT = 0.47 at 623 K, but aluminum (Al) and indium (In) doping When the content was further increased, the ZT value decreased. In this study, it was judged that indium (In) doping is more effective in improving the thermoelectric performance of firmingeartite than aluminum (Al). In addition, the solid-phase synthesis process of mechanical alloying and hot compression molding was a simple and useful process that did not require subsequent heat treatment to produce a doped fermingite compound.

In summary, the ferming geartite Cu ₃ Sb _1-y B ^Ⅲ _y Se ₄ (B ^Ⅲ = Al, In; 0 ≤ y ≤ 0.08) powder synthesized by mechanical alloying was sintered by hot compression molding. Phase change, microstructure, charge transfer, and thermoelectric properties according to the addition of aluminum (Al) or indium (In) dopant to the Sb site were investigated. A single phase of fermingeartite with a tetragonal structure was observed in all specimens. Both undoped and Al/In-doped specimens showed positive Seebeck and Hall coefficients, indicating p-type conduction characteristics. As the Al/In doping content increased, the carrier concentration increased, and as a result, the electrical conductivity increased and the Seebeck coefficient decreased compared to Cu ₃ SbSe ₄ . The thermal conductivity increased by Al/In doping, but the power factor also increased. As a result, the maximum ZT values at 623 K were 0.42 for Cu ₃ Sb _0.96 Al _0.04 Se ₄ and 0.47 for Cu ₃ Sb _0.96 In _0.04 Se ₄ .

In addition, the present invention provides a firmingeartite thermoelectric material doped with aluminum (Al) or indium (In) manufactured by the above method.

In one embodiment of the present invention, when the composition of the thermoelectric material is Cu ₃ Sb _0.96 Al _0.04 Se ₄ or Cu ₃ Sb _0.96 In _0.04 Se _{4 ,} the output power is 0.5 to 0.7 mWm ^-1 K ^-2 at a temperature of 500 to 650K. factor and a thermal conductivity of 0.7 to 0.9 Wm ^-1 K ^-1 .

So far, the present invention has been looked at with respect to its preferred embodiments. Those skilled in the art to which the present invention pertains will be able to understand that the present invention can be implemented in a modified form without departing from the essential characteristics of the present invention. Therefore, the disclosed embodiments should be considered from an illustrative rather than a limiting point of view. The scope of the present invention is shown in the claims rather than the foregoing description, and all differences within the equivalent scope will be construed as being included in the present invention.

Claims (10)

As an indium (In) doped firming geartite thermoelectric material,
The thermoelectric material has a composition of Cu ₃ Sb _0.96 In _0.04 Se ₄ ,
The thermoelectric material may include (a) mixing indium (In) doping element powder with raw materials Cu, Sb, and Se; (b) mechanically alloying the powders mixed in step (a); and (c) hot pressing the alloyed powder through step (b). delete delete delete delete According to claim 1,
In step (b), the powder mixed in step (a) is ball milled at 200 rpm to 600 rpm for 1 hour to 48 hours. According to claim 1,
In the step (c), the hot compression is performed for 1 to 3 hours in a temperature range of 400 to 800K and a pressure range of 10 to 200MPa, indium (In) doped firming geartite thermoelectric material. delete delete According to claim 1,
The thermoelectric material is characterized in that it has a dimensionless figure of merit (ZT) of 0.47 at a temperature of 623K, indium (In) doped firming geartite thermoelectric material.

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