Method for microwave in-situ synthesis of complex-phase CuSbS2 thermoelectric material

Abstract

The invention discloses a method for microwave in-situ synthesis of a complex-phase CuSbS2 thermoelectric material, and belongs to the technical field of novel thermoelectric functional materials. The method comprises the following steps: firstly, according to the stoichiometric ratio Cux (Sb2S3) y (0lt; x < = 1, 1 < = y < lt >; (2) Cu powder and Sb2S3 powder are weighed, and raw materials are evenly mixed through mechanical grinding; and then placing the mixed powder in a microwave heating device under inert atmosphere protection for in-situ reaction to obtain the complex-phase CuSbS2 thermoelectric material. Furthermore, the obtained complex-phase CuSbS2 thermoelectric material can be prepared into a complex-phase CuSbS2 thermoelectric material block through a mold pressing sintering process. The microwave heating in-situ synthesis effect is utilized, copper atoms are promoted to rapidly replace the antimony element in antimony sulfide, and efficient in-situ synthesis of the complex-phase CuSbS2 thermoelectric material can be achieved. The method has the advantages of high reaction speed, low energy consumption, large scale and the like.

Description

Technical Field

[0001] This invention belongs to the field of novel thermoelectric functional materials technology, specifically relating to a method for microwave in-situ synthesis of multiphase CuSbS2 thermoelectric materials. Background Technology

[0002] Under the dual pressures of energy crisis and ecological degradation, thermoelectric conversion technology, with its unique advantage of directly converting heat energy into electrical energy, has become a research hotspot in the field of new energy. Among them, thermoelectric generators (TEGs) based on the Seebeck effect construct power generation units through the coupling of p-type and n-type semiconductors, achieving zero pollutant emissions during waste heat recovery, providing an important technological path for the green transformation of energy systems. However, traditional systems such as Bi2Te3-based materials face resource depletion and toxicity issues, while PbTe-based materials are limited by application bottlenecks in the mid-temperature range, necessitating the development of environmentally friendly alternatives. In recent years, copper-based chalcogenides (such as Cu2S, Cu2Se, and CuSbSe2) have attracted much attention due to their high abundance on Earth, intrinsically low thermal conductivity, and tunable electrical transport properties. CuSbS2, with its two-dimensional layered structure, exhibits excellent lattice thermal resistance while maintaining a high Seebeck coefficient, making it a highly promising candidate material for mid-temperature thermoelectric applications. Unfortunately, CuSbS2 materials have poor electrical conductivity in the near-room temperature range, requiring effective performance improvement strategies.

[0003] More notably, the preparation process of CuSbS2 materials faces significant bottlenecks. Current mainstream methods (such as vacuum deposition, solvothermal synthesis, and solid-state reaction) generally suffer from: (1) harsh high-temperature and high-pressure conditions, resulting in huge energy consumption; (2) extremely long synthesis cycles, leading to low efficiency; and (3) complex post-processing procedures (such as sulfidation), increasing the difficulty and cost of the process. These preparation challenges not only limit the efficiency of materials research but also hinder the exploration of its large-scale applications.

[0004] Recent research has revealed an effective pathway to enhance the thermoelectric properties of CuSbS2. By introducing a second phase to construct a multiphase structure, interfacial phonon scattering can be effectively enhanced, reducing thermal conductivity while maintaining electrical properties. However, the efficient and controllable synthesis of multiphase CuSbS2 materials with optimized phase composition remains a challenge. Traditional synthesis methods are often limited by the aforementioned problems of high energy consumption, long cycle time, and complex processes when trying to achieve this.

[0005] Therefore, there is an urgent need to develop a new synthesis technology that can simultaneously solve the bottlenecks in CuSbS2 preparation (high efficiency, low temperature, rapid, and no post-treatment) and accurately construct high-performance multiphase structures. Summary of the Invention

[0006] Based on the problems existing in the background technology, the present invention provides a method for in-situ synthesis of a composite CuSbS2 thermoelectric material by microwave. The in-situ prepared composite material has a near-room-temperature conductivity of 10200 S / m and a low thermal conductivity of 0.991 μW·m x , , y ,

[0011] ,

[0013] , ,

[0012] , ·K 2 ,and the ZT value reaches 0.393, which are 1.23 times, 0.9 times and 2.16 times that of the pure-phase CuSbS2 sample under the same conditions, respectively. In addition, compared with the traditional preparation method, the process of in-situ synthesis of composite CuSbS2 by microwave has the advantages of low energy consumption, short cycle and no pollution. <(

[0007] The chemical composition of the composite CuSbS2 thermoelectric material prepared by the present invention is Cu x (Sb2S3) y , where 0 < x ≤ 1 and 1 ≤ y < 2; the Cu raw material and the Sb2S3 raw material are prepared according to the ratio, and after mechanical grinding and mixing, the composite CuSbS2 thermoelectric material is obtained by microwave heating; after crushing, molding by pressing and sintering in an oxygen-free atmosphere, a bulk composite CuSbS2 thermoelectric material is obtained.

[0008] The present invention optimizes the CuSbS2 synthesis process, proposes a strategy for enhancing the thermoelectric performance of the composite material, and uses the microwave effect to promote the replacement of Sb element in Sb2S3 by Cu to directly synthesize CuSbS2 in-situ and grow Sb单质 in-situ. The presence of the Sb单质 phase at the grain boundaries of CuSbS2 strengthens phonon scattering while reducing the difficulty of carrier migration, effectively improving the thermoelectric performance of the material.

[0009] To achieve the above technical objectives, the present invention provides the following technical solutions:

[0010] One of the technical solutions provided by the present invention: A method for in-situ synthesis of a composite CuSbS2 thermoelectric material by microwave, comprising the following steps:

[0011] (1) Calculate and weigh the Cu raw material and the Sb2S3 raw material according to the stoichiometric ratio of Cu x (Sb2S3) y , and obtain a uniformly mixed raw material powder by mechanical grinding, where 0 < x ≤ 1 and 1 ≤ y < 2; <(

[0012] (2) Transfer the uniformly mixed raw material powder obtained in step (1) to a microwave heating device, and heat it by microwave in an inert atmosphere to obtain a composite CuSbS2 thermoelectric material.

[0013] Optionally, according to the stoichiometric ratio described in step (1); where x can be 0.1, 0.2, 0.4, 0.5, 0.8, 1, etc., and y can be 1, 1.2, 1.5, 1.6, 1.8, 1.9, etc., but is not limited to the listed values, and other unlisted values within the above value range are equally applicable.

[0014] Preferably, the purity of both the Cu raw material and the Sb2S3 raw material in step (1) is not less than 99%, for example, it can be 99.5%, 99.95%, 99.995%, etc., but it is not limited to the listed values. Other unlisted values ​​within the above range are also applicable.

[0015] Preferably, the particle size of the raw material powder in step (1) is 100 to 1000 nm, for example, it can be 100 nm, 150 nm, 200 nm, 300 nm, 400 nm, 500 nm, 600 nm, 700 nm, 800 nm, 900 nm, 1000 nm, etc.; but it is not limited to the listed values, and other unlisted values ​​within the above range are also applicable.

[0016] Preferably, the mechanical grinding time in step (1) is 5 to 30 minutes, for example, 5 minutes, 10 minutes, 15 minutes, 20 minutes, 25 minutes, 30 minutes, etc., but it is not limited to the listed values. Other unlisted values ​​within the above range are also applicable.

[0017] Preferably, the microwave heating temperature in step (2) is 350 to 600°C, such as 350°C, 400°C, 450°C, 500°C, 550°C, 600°C, etc., but is not limited to the listed values. Other unlisted values ​​within the above range are also applicable.

[0018] Preferably, the microwave heating holding time in step (2) is 30 to 180 minutes. The holding time can be 30 minutes, 60 minutes, 80 minutes, 90 minutes, 120 minutes, 150 minutes, 180 minutes, etc., but is not limited to the listed values. Other unlisted values ​​within the above range are also applicable.

[0019] Preferably, the heating rate of microwave heating in step (2) is 20 to 40 °C / min. For example, it can be 20 °C / min, 21 °C / min, 25 °C / min, 27 °C / min, 30 °C / min, 35 °C / min, 40 °C / min, etc., but it is not limited to the listed values. Other unlisted values ​​within the above range are also applicable.

[0020] Optionally, the inert atmosphere described in step (2) includes, but is not limited to, nitrogen, argon or helium atmosphere.

[0021] The second technical solution provided by this invention: A multiphase CuSbS2 thermoelectric material prepared according to the above-mentioned microwave in-situ synthesis method for multiphase CuSbS2 thermoelectric materials, wherein the chemical composition of the multiphase CuSbS2 thermoelectric material is Cu x(Sb2S3) y , of which 0 <x≤1,1≤y<2。

[0022] The third technical solution provided by the present invention is a multiphase CuSbS2 thermoelectric material block, specifically, the multiphase CuSbS2 thermoelectric material is pulverized, molded, and sintered to obtain the multiphase CuSbS2 thermoelectric material block.

[0023] Preferably, the particle size of the pulverized multiphase CuSbS2 thermoelectric material is ≤150μm, for example, 50μm, 70μm, 100μm, 120μm, 150μm, etc., but it is not limited to the listed values. Other unlisted values ​​within the above range are also applicable.

[0024] Preferably, the equivalent pressure of the compression molding is 10 to 20 MPa, such as 10 MPa, 12 MPa, 15 MPa, 17 MPa, 20 MPa, etc., but it is not limited to the listed values. Other unlisted values ​​within the above range are also applicable.

[0025] Preferably, the heating rate during sintering is 5–20 °C / min. The heating rate can be 5 °C / min, 7 °C / min, 11 °C / min, 15 °C / min, 20 °C / min, etc., but is not limited to the listed values; other unlisted values ​​within the above range are also applicable. The purpose of controlling the heating rate is to avoid excessively rapid heating during sintering, which could lead to uncontrollable defects caused by the volatilization of material components.

[0026] Preferably, the sintering temperature is 400-550°C, for example, 400°C, 450°C, 500°C, 550°C, etc., but it is not limited to the listed values. Other unlisted values ​​within the above range are also applicable.

[0027] Preferably, the holding time during sintering is 60 to 90 minutes, such as 60 minutes, 70 minutes, 80 minutes, 90 minutes, etc., but it is not limited to the listed values. Other unlisted values ​​within the above range are also applicable.

[0028] Preferably, the sintering is carried out in a uniform thermal field and an oxygen-free environment. The uniform thermal field is provided by sintering equipment including but not limited to resistance furnaces and microwave ovens, and the oxygen-free environment includes but is not limited to carbon-buried environments and inert atmosphere environments. An oxygen-free environment can prevent the sample from oxidizing during heating, and a uniform thermal field can reduce component volatilization and avoid the generation of uncontrollable defects.

[0029] The fourth technical solution provided by the present invention is an application of the above-mentioned multiphase CuSbS2 thermoelectric material bulk, characterized in that the multiphase CuSbS2 thermoelectric material bulk is used to prepare photothermal-thermal cogeneration devices.

[0030] Compared with the prior art, the beneficial technical effects of the present invention are as follows:

[0031] (1) By using microwave heating technology, copper is driven to replace the antimony element in antimony sulfide with microwave energy, which can quickly and efficiently synthesize multiphase CuSbS2 thermoelectric materials. The synthesis process is clean and pollution-free, with low energy consumption and high efficiency.

[0032] (2) The second phase grown in situ optimizes the carrier transport and phonon scattering characteristics, forming a better balance between electrical conductivity and thermal conductivity, effectively improving the thermoelectric performance of copper-based chalcogenide thermoelectric materials and meeting the needs of medium and low temperature thermoelectric power generation scenarios.

[0033] (3) As a novel thermoelectric material composed of non-scarce and non-toxic elements, the multiphase CuSbS2 thermoelectric material has a richer raw material reserve, lower cost and environmental friendliness, and is easier to achieve large-scale production and commercial application. It is a highly promising candidate material in the field of thermoelectric power generation. Attached Figure Description

[0034] Figure 1 The flowcharts for preparing bulk CuSbS2 thermoelectric materials in Examples 1-4 of this invention are shown.

[0035] Figure 2 This is a schematic diagram of steps (1) to (5) in Embodiment 1 of the present invention.

[0036] Figure 3 The images show the XRD patterns of the CuSbS2 thermoelectric materials prepared in Examples 1-4 and Comparative Examples 1-2 of this invention.

[0037] Figure 4 The images shown are SEM images and EDS spectra of different locations of the bulk CuSbS2 thermoelectric material sample prepared in Example 1 of this invention. Among them, (a) is the first microstructure of the bulk CuSbS2 thermoelectric material sample, (b) to (d) are the mapping images of S, Sb and Cu corresponding to (a), (e) is the EDS image corresponding to (a), (f) is the second microstructure of the bulk CuSbS2 thermoelectric material sample, (g) to (i) are the mapping images of S, Sb and Cu corresponding to (f), and (j) is the EDS image corresponding to (f).

[0038] Figure 5 Seebeck coefficient (a), electrical conductivity (b), thermal conductivity (c), and power factor (d) of CuSbS2 thermoelectric material bulk samples prepared in Examples 1-4 and Comparative Examples 1-2 of this invention.

[0039] Figure 6 ZT values ​​are the CuSbS2 thermoelectric material bulk samples prepared in Examples 1-4 and Comparative Examples 1-2 of this invention. Detailed Implementation

[0040] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as a limitation of the present invention, but rather as a more detailed description of certain aspects, features, and embodiments of the present invention. It should be understood that the terminology used in this invention is merely for describing particular embodiments and is not intended to limit the present invention.

[0041] It should be noted that any aspects not described in detail in this invention are conventional practices in the field and are not the focus of this invention.

[0042] Furthermore, regarding the numerical ranges in this invention, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Any stated value or intermediate value within a stated range, as well as each smaller range between any other stated value or intermediate value within said range, are also included in this invention. The upper and lower limits of these smaller ranges may be independently included or excluded from the range.

[0043] Unless otherwise stated, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. While only preferred methods and materials have been described herein, any methods and materials similar to or equivalent to those described herein may be used in the implementation or testing of this invention.

[0044] The terms “include,” “including,” “have,” “contain,” etc., used in this article are all open-ended terms, meaning that they include but are not limited to.

[0045] Unless otherwise specified, room temperature and normal temperature as used in this invention refer to a temperature of 20±10℃.

[0046] The flowcharts for preparing the bulk CuSbS2 thermoelectric material in Examples 1-4 of this invention are shown below. Figure 1 .

[0047] The operation diagram of steps (1) to (5) in Embodiment 1 of the present invention is shown below. Figure 2 .

[0048] Example 1

[0049] (1) According to Cu x (Sb2S3) y According to the stoichiometric ratio, Cu powder and Sb2S3 powder with a purity of ≥99% were mixed in a molar ratio of 0.8:1.2 and then ground in a ball mill. Anhydrous ethanol was added to the ball mill as a grinding agent and ground for 30 minutes to mix evenly, thus obtaining a mixed powder.

[0050] (2) The above mixed powder was transferred into a quartz boat with dimensions of 50mm×40mm×20mm and then placed in a microwave tube furnace. During the synthesis process, argon gas was introduced into the microwave tube furnace as a protective gas and heated to 400℃ at a heating rate of 27℃ / min. The temperature was then maintained at this temperature for 90min to complete the sample preparation. After the reaction was completed, the sample was cooled to room temperature and then removed to obtain the multiphase CuSbS2 thermoelectric material.

[0051] (3) After the synthesis reaction is completed, continue to maintain the argon protective atmosphere and let it cool naturally to room temperature. Then take out the product and grind it until the particle size is less than 150 μm.

[0052] (4) Accurately weigh 0.5g of the multiphase CuSbS2 powder material obtained in step (3), and place it in an inner diameter of [missing information]. In the mold, a HY-12 type powder tablet press is used to form the tablets under a pressure of 12MPa for 60 seconds.

[0053] (5) The block sample obtained in step (4) was completely covered with carbon paper and placed in an alumina crucible and sealed with carbon particles. It was then sintered in a muffle furnace at a heating rate of 5℃ / min to 450℃ and held for 80min. This process improved the bonding and densification of the powder particles. After cooling the sample to room temperature, it was removed to obtain a block sample of multiphase CuSbS2 thermoelectric material.

[0054] Example 2

[0055] (1) According to Cu x (Sb2S3) y According to the stoichiometric ratio, Cu powder and Sb2S3 powder with a purity of ≥99% were mixed in a molar ratio of 0.4:1.6 and then ground in a ball mill. Anhydrous ethanol was added to the ball mill as a grinding agent, and the mixture was ground for 20 minutes to obtain a uniform powder.

[0056] (2) The above mixed powder was transferred into a quartz boat with dimensions of 50mm×40mm×20mm and then placed in a microwave tube furnace. During the synthesis process, nitrogen gas was introduced into the microwave tube furnace as a protective gas and heated to 350℃ at a heating rate of 35℃ / min. The temperature was then maintained at this temperature for 180min to complete the sample preparation. After the reaction was completed, the sample was cooled to room temperature and then removed to obtain the multiphase CuSbS2 thermoelectric material.

[0057] (3) After the synthesis reaction is completed, continue to maintain the nitrogen protective atmosphere and let it cool naturally to room temperature. Then take out the product and grind it until the particle size is less than 150 μm.

[0058] (4) Accurately weigh 0.5g of the multiphase CuSbS2 powder material obtained in step (3), and place it in an inner diameter of [missing information]. The mold is formed using a HY-12 type powder tablet press, which holds pressure for 60 seconds under a gauge pressure of 10MPa.

[0059] (5) The block sample obtained in step (4) is placed in a quartz boat and further sintered in a microwave tube furnace with argon gas. The temperature is raised to 400℃ at a heating rate of 11℃ / min and held for 90min. This allows for better bonding and densification between the powder particles. After the sample is cooled to room temperature, it is taken out to obtain a block sample of multiphase CuSbS2 thermoelectric material.

[0060] Example 3

[0061] (1) According to Cu x (Sb2S3) y According to the stoichiometric ratio, Cu powder and Sb2S3 powder with a purity of ≥99% were mixed in a 1:1 molar ratio and then ground in a ball mill. Anhydrous ethanol was added to the ball mill as a grinding agent, and the mixture was ground for 15 minutes to obtain a homogeneous powder.

[0062] (2) The above mixed powder was transferred into a quartz boat with dimensions of 50mm×40mm×20mm and then placed in a microwave tube furnace. During the synthesis process, argon gas was introduced into the microwave tube furnace as a protective gas and heated to 600℃ at a heating rate of 40℃ / min. The temperature was then maintained for 30min to complete the sample preparation. After the reaction was completed, the sample was cooled to room temperature and then removed to obtain the multiphase CuSbS2 thermoelectric material.

[0063] (3) After the synthesis reaction is completed, continue to maintain the argon protective atmosphere and let it cool naturally to room temperature. Then take out the product and grind it until the particle size is less than 150 μm.

[0064] (4) Accurately weigh 0.5g of the multiphase CuSbS2 powder material obtained in step (3), and place it in an inner diameter of [missing information]. In the mold, a HY-12 type powder tablet press is used to form the tablets under a pressure of 20MPa for 60 seconds.

[0065] (5) The block sample obtained in step (4) is placed in a quartz boat and further sintered in a conventional tube furnace with nitrogen gas. The temperature is raised to 550°C at a heating rate of 20°C / min and held for 60 min. This allows for better bonding and densification between the powder particles. After the sample is cooled to room temperature, it is taken out to obtain a block sample of multiphase CuSbS2 thermoelectric material.

[0066] Example 4

[0067] (1) According to Cu x (Sb2S3) yAccording to the stoichiometric ratio, Cu powder and Sb2S3 powder with a purity of ≥99% were mixed in a molar ratio of 0.1:1.9 and then ground in a ball mill. Anhydrous ethanol was added to the ball mill as a grinding agent, and the mixture was ground for 5 minutes to obtain a uniform powder.

[0068] (2) The above mixed powder was transferred into a quartz boat with dimensions of 50mm×40mm×20mm and then placed in a microwave tube furnace. During the synthesis process, nitrogen gas was introduced into the microwave tube furnace as a protective gas and heated to 450℃ at a heating rate of 21℃ / min. The temperature was then maintained at this temperature for 120min to complete the sample preparation. After the reaction was completed, the sample was cooled to room temperature and then removed to obtain the multiphase CuSbS2 thermoelectric material.

[0069] (3) After the synthesis reaction is completed, continue to maintain the nitrogen protective atmosphere and let it cool naturally to room temperature. Then take out the product and grind it until the particle size is less than 150 μm.

[0070] (4) Accurately weigh 0.5g of the multiphase CuSbS2 powder material obtained in step (3), and place it in an inner diameter of [missing information]. In the mold, a HY-12 type powder tablet press is used to form the tablets under a pressure of 15MPa for 60 seconds.

[0071] (5) The block sample obtained in step (4) was completely covered with carbon paper and placed in an alumina crucible and sealed with carbon particles. It was then further sintered in a resistance furnace at a heating rate of 15℃ / min to 500℃ and held for 70min. This process improved the bonding and densification between the powder particles. After cooling the sample to room temperature, it was removed to obtain a block sample of multiphase CuSbS2 thermoelectric material.

[0072] Comparative Example 1

[0073] (1) According to the stoichiometric ratio of CuSbS2, Cu powder, Sb powder and S powder with a purity of ≥99% were mixed in a molar ratio of 1:1:2 and then ground in a ball mill. Anhydrous ethanol was added to the ball mill as a grinding agent and ground for 30 minutes to mix evenly to obtain a mixed powder.

[0074] (2) The above mixed powder was transferred into a quartz boat with dimensions of 50mm×40mm×20mm and then placed in a microwave tube furnace. During the synthesis process, argon gas was introduced into the microwave tube furnace as a protective gas and heated to 400℃ at a heating rate of 27℃ / min. The temperature was then maintained at this temperature for 90min to complete the sample preparation. After the reaction was completed, the sample was cooled to room temperature and then removed to obtain pure phase CuSbS2 thermoelectric material.

[0075] (3) After the synthesis reaction is completed, continue to maintain the argon protective atmosphere and let it cool naturally to room temperature. Then take out the product and grind it until the particle size is less than 150 μm.

[0076] (4) Accurately weigh 0.5g of the pure phase CuSbS2 powder material obtained in step (3) and place it in an inner diameter of [missing information]. In the mold, a HY-12 type powder tablet press is used to form the tablets under a pressure of 12MPa for 60 seconds.

[0077] (5) The block sample obtained in step (4) was completely covered with carbon paper and placed in an alumina crucible and sealed with carbon particles. It was then sintered in a resistance furnace at a heating rate of 5℃ / min to 450℃ and held for 80min. This process improved the bonding and densification of the powder particles. After cooling the sample to room temperature, it was removed to obtain a block sample of pure phase CuSbS2 thermoelectric material.

[0078] Comparative Example 2

[0079] (1) According to Cu x (Sb2S3) y According to the stoichiometric ratio, Cu powder and Sb2S3 powder with a purity of ≥99% were mixed in a molar ratio of 0.8:1.2 and then ground in a ball mill. Anhydrous ethanol was added to the ball mill as a grinding agent and ground for 30 minutes to mix evenly, thus obtaining a mixed powder.

[0080] (2) The above mixed powder was transferred into a quartz boat with dimensions of 50mm×40mm×20mm and then placed in a conventional tube furnace. During the synthesis process, argon gas was introduced into the conventional tube furnace as a protective gas and heated to 400℃ at a heating rate of 10℃ / min. The temperature was then maintained at this temperature for 90min to complete the sample preparation. After the reaction was completed, the sample was cooled to room temperature and then removed to obtain the multiphase CuSbS2 thermoelectric material.

[0081] (3) After the synthesis reaction is completed, continue to maintain the argon protective atmosphere and let it cool naturally to room temperature. Then take out the product and grind it until the particle size is less than 150 μm.

[0082] (4) Accurately weigh 0.5g of the multiphase CuSbS2 powder material obtained in step (3), and place it in an inner diameter of [missing information]. In the mold, a HY-12 type powder tablet press is used to form the tablets under a pressure of 12MPa for 60 seconds.

[0083] (5) The block sample obtained in step (4) is completely covered with carbon paper and placed in an alumina crucible and sealed with carbon particles. It is then subjected to further resistance furnace sintering treatment, with the temperature raised to 450°C at a heating rate of 5°C / min and held for 80 min. This process improves the bonding and densification between the powder particles. After the sample is cooled to room temperature, it is removed to obtain a block sample of multiphase CuSbS2 thermoelectric material.

[0084] The performance test results of the CuSbS2 thermoelectric material bulk samples in the above embodiments and comparative examples are listed in Table 1.

[0085] Table 1

[0086]

[0087]

[0088] The XRD patterns of the CuSbS2 thermoelectric materials prepared in Examples 1-4 and Comparative Examples 1-2 are shown below. Figure 3 .

[0089] from Figure 3 As can be seen from the results, copper substitution of antimony sites in antimony sulfide to synthesize CuSbS2 thermoelectric materials, and the multiphase CuSbS2 thermoelectric materials prepared under different stoichiometric ratios, different grinding times, and different synthesis temperatures, show that the main phase of the XRD diffraction pattern changes to CuSbS2 (PDF#44-1417), and the multiphase is Sb2S3 (PDF#42-1393), indicating that multiphase CuSbS2 was obtained. The pure phase CuSbS2 prepared by microwave sintering (Comparative Example 1) has diffraction peaks that can be attributed to CuSbS2 (PDF#44-1417) and no other impurity phase characteristic peaks, indicating that pure phase CuSbS2 was synthesized.

[0090] SEM images and EDS spectra of different locations of the bulk CuSbS2 thermoelectric material sample prepared in Example 1 are shown below. Figure 4 In the figure, (a) is the first microstructure of the bulk sample of the multiphase CuSbS2 thermoelectric material, (b) to (d) are the mapping diagrams of S, Sb and Cu corresponding to (a), (e) is the EDS diagram corresponding to (a), (f) is the second microstructure of the bulk sample of the multiphase CuSbS2 thermoelectric material, (g) to (i) are the mapping diagrams of S, Sb and Cu corresponding to (f), and (j) is the EDS diagram corresponding to (f).

[0091] from Figure 4 As can be seen, the prepared bulk CuSbS2 thermoelectric material exhibits two different micromorphologies, one being a highly dense layered crystal structure. Figure 4a) The adhesion between particles is beneficial to enhancing the electrical conductivity of the material; an EDS-Mapping scan was performed on it, and the elemental distribution mapping map ( Figure 4 bc) further confirms the material's compositional uniformity. Another type forms an interconnected network structure with irregular pores and gaps between particles. Figure 4 f), the strong phonon scattering from the gaps causes a significant decrease in lattice conductivity; from the elemental distribution mapping diagram ( Figure 4 As can be seen from the gi), the three elements S, Sb, and Cu are evenly distributed. These two different microstructures work synergistically to enhance the thermoelectric properties of the material.

[0092] The Seebeck coefficient (a), electrical conductivity (b), thermal conductivity (c), and power factor (d) of the CuSbS2 thermoelectric material bulk samples prepared in Examples 1-4 and Comparative Examples 1-2 are shown in [reference needed]. Figure 5 The ZT values ​​of the CuSbS2 thermoelectric material bulk samples prepared in Examples 1-4 and Comparative Examples 1-2 are shown in the figure. Figure 6 .

[0093] from Figure 5 It can be seen that, within the temperature range of 298–373 K, the Seebeck coefficient of the bulk CuSbS2 thermoelectric material prepared in Example 1 is significantly higher than that of the bulk CuSbS2 thermoelectric material prepared in Comparative Example 1 and other control samples, and the Seebeck coefficient shows a clear upward trend. Although the electrical conductivity decreases with increasing temperature, it is still significantly higher than that of the bulk CuSbS2 thermoelectric material prepared in Comparative Example 1 and other control samples. Meanwhile, the thermal conductivity shows a decreasing trend, which may be due to the enhanced phonon scattering of the multiphase material, thereby optimizing the thermoelectric performance of the material. Although the electrical conductivity decreases with increasing temperature, the power factor (PF) still shows an increasing trend, indicating that the improvement in the Seebeck coefficient has a dominant contribution to the thermoelectric performance.

[0094] Compared to the bulk CuSbS2 thermoelectric material samples synthesized in a conventional tube furnace (Comparative Example 2), the material synthesized in situ using microwave exhibits superior thermoelectric properties: specifically, at 373 K, the Seebeck coefficient significantly increases from 181.346 μV / K to 320.147 μV / K, an increase of nearly 80%; the electrical conductivity more than doubles, increasing from 5168 S / m to 10200 S / m, an increase of approximately 2 times; and the thermal conductivity increases from 1.112 μW·m. -1 ·K 2 Reduced to 0.991 μW·m -1 ·K 2This effectively optimized the heat transport characteristics; and the thermoelectric figure of merit (ZT), reflecting the overall performance, jumped significantly from 0.061 to 0.393, an improvement of more than 5 times. These data clearly demonstrate that the bulk CuSbS2 thermoelectric material samples prepared by microwave tube furnace exhibit significant advantages in thermoelectric performance, with key performance parameters far superior to those prepared by conventional tube furnace processes. This provides a more promising technical path for the efficient preparation of high-performance thermoelectric materials.

[0095] In addition, combined Figure 6 ZT value analysis revealed that the bulk CuSbS2 thermoelectric material prepared in Example 1 exhibited a high ZT value at room temperature. The ZT value increased significantly with increasing temperature, and was significantly higher than that of the pure CuSbS2 thermoelectric material bulk sample and other control samples. This result further confirms the excellent thermoelectric properties of the bulk CuSbS2 thermoelectric material, providing strong support for its practical application at room temperature.

[0096] In summary, this invention effectively improves the thermoelectric properties of CuSbS2 thermoelectric material bulk samples by precisely controlling the raw material ratio. The resulting materials were then tested to assess the changes in electrical and thermal properties with temperature (including Seebeck coefficient, electrical conductivity, thermal diffusivity, specific heat capacity, etc.). Example 1 (Microwave Cu 0.8 (Sb2S3) 1.2 It exhibits superior performance in all aspects (-30min-400℃).

[0097] The embodiments described above are merely preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Various modifications and improvements made by those skilled in the art to the technical solutions of the present invention without departing from the spirit of the present invention should fall within the protection scope defined by the claims of the present invention.

Claims

1. A method for microwave in-situ synthesis of multiphase CuSbS2 thermoelectric materials, characterized in that, Includes the following steps: (1) First, according to Cu x (Sb2S3) y The stoichiometric ratio of Cu and Sb₂S₃ raw materials was calculated by weighing and mechanically grinding to obtain a uniformly mixed raw material powder, wherein 0 <x≤1,1≤y<2; (2) The uniform raw material powder obtained in step (1) is transferred to a microwave heating device and microwave heated under an inert atmosphere to obtain a multiphase CuSbS2 thermoelectric material.

2. The method for microwave in-situ synthesis of multiphase CuSbS2 thermoelectric materials according to claim 1, characterized in that, The purity of the Cu raw material and the Sb2S3 raw material in step (1) is not less than 99%; the mechanical grinding time is 5 to 30 minutes; and the particle size of the raw material powder is 100 to 1000 nm.

3. The method for microwave in-situ synthesis of multiphase CuSbS2 thermoelectric materials according to claim 1, characterized in that, The heating rate of microwave heating in step (2) is 20-40℃ / min, the holding temperature is 350-600℃, and the holding time is 30-180min; the inert atmosphere includes nitrogen, argon or helium environment.

4. A multiphase CuSbS2 thermoelectric material prepared by the microwave in-situ synthesis method according to any one of claims 1 to 3, characterized in that, The chemical composition of the aforementioned multiphase CuSbS2 thermoelectric material is Cu x (Sb2S3) y , of which 0 <x≤1,1≤y<2。 5. A bulk CuSbS2 thermoelectric material, characterized in that, Specifically, the multiphase CuSbS2 thermoelectric material described in claim 4 is pulverized, molded, and sintered to obtain a block of the multiphase CuSbS2 thermoelectric material.

6. The bulk CuSbS2 thermoelectric material according to claim 5, characterized in that, The particle size of the pulverized multiphase CuSbS2 thermoelectric material powder is ≤150μm.

7. The bulk CuSbS2 thermoelectric material according to claim 5, characterized in that, The equivalent pressure of the compression molding is 10-20 MPa.

8. The bulk CuSbS2 thermoelectric material according to claim 5, characterized in that, The heating rate during sintering is 5–20 °C / min, the sintering temperature is 400–550 °C, and the holding time is 60–90 min.

9. The bulk CuSbS2 thermoelectric material according to claim 5, characterized in that, The sintering is carried out in a uniform thermal field and an oxygen-free environment.

10. An application of the multiphase CuSbS2 thermoelectric material bulk according to claim 5, characterized in that, The aforementioned multiphase CuSbS2 thermoelectric material bulk is used to prepare photothermal-thermal-cogeneration devices.

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