N-type lead selenide thermoelectric material and preparation method and application thereof

Abstract

The invention discloses an n-type lead selenide thermoelectric material and a preparation method and application thereof, and belongs to the technical field of thermoelectric material preparation. The chemical formula of the n-type lead selenide thermoelectric material is Pb1-x (AlSb) xSe (x is more than or equal to 0.0025 and less than or equal to 0.006); the material is prepared by combining a hot melting method with a plasma sintering method. According to the Pb1-x (AlSb) xSe thermoelectric material prepared by the method, Al and Sb elementary substances are doped at the Pb position, so that the conductivity of the n-type lead selenide thermoelectric material can be effectively improved. Compared with the existing n-type lead selenide thermoelectric material, the prepared Pb < 0.9965 > (AlSb) 0.0035 Se material has the maximum thermoelectric figure of merit at 923K. The thermoelectric figure of merit of the n-type lead selenide thermoelectric material can be greatly improved, and the high thermoelectric figure of merit is beneficial to improving the conversion efficiency of a thermoelectric power generation device.

Description

Technical Field

[0001] This invention belongs to the field of thermoelectric material preparation technology, specifically relating to an n-type lead selenide thermoelectric material, its preparation method, and its application. Background Technology

[0002] Today, with the increasing prevalence of chemical energy shortages and environmental pollution, the development of green energy technologies is receiving growing attention from industry and academia. In particular, a significant amount of waste heat from energy dissipation during human life and production goes unused. Thermoelectric materials are environmentally friendly functional materials that can directly convert heat energy into electrical energy, and can generate electricity using the Seebeck effect. Thermoelectric power generation devices have unique advantages such as small size, no noise, high reliability, fast response, and long lifespan. They have wide applications in areas such as using the temperature difference generated by nuclear fission reactors of radioactive elements to provide power to remote locations in space or deep sea, using human body heat as a heat source for wearable small electrical appliances, and converting automobile exhaust into energy for vehicle lights, demonstrating enormous commercial potential.

[0003] Since the 1950s, PbTe has been widely used in electronic devices such as sensors and infrared detectors as one of the best thermoelectric materials in the mid-temperature range (400-800K). However, due to the extremely low abundance of Te in the Earth's crust (even less than Pt and Au), its high price prevents large-scale use. Therefore, finding an element to replace Te in PbTe is essential. PbSe and PbTe both belong to group IV-VI semiconductor materials, with very similar crystal and band structures, and similar physicochemical properties and crystal structures. Compared to PbTe, PbSe has a higher melting point, making it possible for the material to operate in higher-temperature environments; the natural abundance of Se is nearly 50 times that of Te, and it also has a greater cost advantage over PbTe. Therefore, PbSe is considered a promising alternative to PbTe.

[0004] Therefore, through research, many n-type PbSe thermoelectric materials with excellent thermoelectric properties have been developed, and the introduction of doping with other elements can improve the thermoelectric figure of merit of n-type PbSe thermoelectric materials.

[0005] Cu doping can optimize the thermoelectric performance of PbSe-based thermoelectric materials, but excessive Cu and Se can easily generate impurity phases, requiring the addition of Pb and precise control of Cu dosage to mitigate these impurity phases. Chinese patent document CN106711317A discloses a chalcogenide thermoelectric material and its preparation method. Using high-purity elemental materials as raw materials, the process involves vacuum encapsulation, high-temperature melting, annealing heat treatment, grinding into powder, and then vacuum hot-pressing sintering followed by slow cooling to obtain a high-performance PbSe-based thermoelectric material. 1-x Sb 2x / 3The novel Se thermoelectric material exhibits a thermoelectric figure of merit (ZT) of 1.6 at 900K, the highest among Sb-doped PbSe materials. The Sb-doped PbSe-based thermoelectric material prepared by this method requires prolonged heat treatment and extremely high hot-pressing pressure to induce lattice dislocations, thereby reducing thermal conductivity and improving its thermoelectric performance. Although high-temperature and high-pressure preparation conditions can increase lattice stress and lower dislocation energy barriers, the energy consumption required for prolonged high-temperature and high-pressure reactions is enormous.

[0006] Therefore, it is essential to develop a high-performance, low-cost PbSe material and its preparation method that are simple to prepare. Summary of the Invention

[0007] The purpose of this invention is to provide an n-type lead selenide thermoelectric material, its preparation method and application. This method, through an aluminum and antimony dual-doping process, significantly shortens the heat treatment time, reduces hot-pressing pressure, lowers energy consumption, and reduces production costs while ensuring the thermoelectric figure of merit of the product.

[0008] To achieve the above objectives, the present invention adopts the following technical solution: In a first aspect, the present invention provides an n-type lead selenide thermoelectric material, wherein the chemical formula of the n-type lead selenide thermoelectric material is Pb. 1-x (AlSb) x Se; where 0.0025≤x≤0.006.

[0009] Secondly, this invention provides a method for preparing n-type lead selenide thermoelectric materials, specifically including the following steps: (1) According to the chemical formula Pb 1-x (AlSb) x In the stoichiometric ratio of Se, 0.0025≤x≤0.006, elemental Pb, Al, Sb, and Se are weighed, mixed, and then heated under vacuum to undergo a melting reaction to obtain Pb. 1-x (AlSb) x Se material precursors; (2) Pb 1-x (AlSb) x Se material precursors are ground, sintered into blocks, and sliced ​​to obtain n-type lead selenide thermoelectric materials; the sintering is carried out by heating to 500-600℃ at a heating rate of 50-100℃ / min and holding at that temperature for 5-15min; the sintering pressure is 30-40MPa.

[0010] Preferably, in step (1), the melting reaction is carried out by heating to 1000-1200℃ at a heating rate of 80-100℃ / h and holding at that temperature for 3-6h.

[0011] Thirdly, the present invention provides an application of the above-mentioned n-type lead selenide thermoelectric material in thermoelectric conversion devices.

[0012] Compared with the prior art, the present invention has the following beneficial effects: 1. The n-type lead selenide thermoelectric material provided by the present invention contains two doping elements, Al and Sb, in equimolar amounts. Equimolar doping of Al and Sb elements can significantly improve the thermoelectric figure of merit of the thermoelectric material. As can be seen from the data in Table 1, the thermoelectric figure of merit of the thermoelectric materials prepared in Examples 1 to 6 is 1.21 to 1.65; especially Example 3, which uses Pb 0.9965 (AlSb) 0.0035 Thermoelectric materials prepared by weighing elemental Pb, Al, Sb, and Se in stoichiometric proportions in Se exhibit a thermoelectric figure of merit (TGI) as high as 1.65. This represents an improvement of nearly 305% compared to the pure-phase thermoelectric material in Comparative Example 1, and a significant improvement compared to the single-doped thermoelectric materials in Comparative Examples 2-3 and the non-equimolarly doped thermoelectric materials in Comparative Examples 4-5. 0.9965 (AlSb) 0.0035 Se exhibits the highest thermoelectric figure of merit (TFP) of 1.65 at 923 K, representing an improvement of nearly 305%, 75–101%, and 58–70% over pure-phase, single-doped, and non-equimolarly-doped PbSe, respectively. This is significantly higher than the TFP of Pb disclosed in CN106711317A. 1-x Sb 2x / 3The thermoelectric figure of merit of the new Se thermoelectric material is improved by 3%. 2. This invention modifies the PbSe-based thermoelectric material by equimolar co-doping with Al and Sb. Since the melting point of Al is higher than that of Pb, Se and Sb, and the atomic radius of Al is much smaller than that of Pb, it can induce lattice dislocations by generating lattice distortion during crystal growth. This can significantly reduce the sintering temperature, sintering pressure and sintering time of the sintering process in step (2). The sintering temperature, sintering pressure and holding time of the sintering block of this invention are 500-600℃, 30-40℃ and 30-40℃ respectively. The sintering temperature, sintering pressure, and holding time of step (4) of the method for preparing chalcogenide thermoelectric materials disclosed in CN106711317A are 650~750℃, 80~100MPa, and 60min, respectively. Compared with this method, the sintering temperature, sintering pressure, and holding time of the present invention are significantly reduced. This not only reduces energy consumption, shortens process time, and reduces process operation difficulty, but also lowers equipment requirements and significantly saves equipment investment. In addition, the lower sintering temperature, lower pressure, and shorter holding time are conducive to the formation of fine and uniform grain structure of PbSe-based thermoelectric materials and the reduction of internal stress to avoid the generation of microcracks. In particular, the addition of Al element induces the formation of lattice dislocations during sintering, and the stable existence of these lattice dislocations inhibits the increase of thermal conductivity. Overall, the optimization of process parameters for equimolar co-doped PbSe-based thermoelectric materials with Al and Sb not only improves preparation efficiency but also comprehensively enhances the thermoelectric figure of merit by finely controlling the microstructure, providing a new pathway for the preparation of high-performance thermoelectric materials. 3. Compared with copper-doped thermoelectric materials, the n-type thermoelectric material preparation method provided by this invention is less prone to impurity phase generation, has lower requirements for the preparation process, and can better improve the reproducibility and stability of the prepared materials. Compared with Ag and Te-doped methods, Al and Sb are cheaper, and Al reserves are relatively large, making it easy to scale up production. Attached Figure Description

[0013] Figure 1 Pb in Examples 1-6 of this invention 1-x (AlSb) x X-ray diffraction patterns of powders prepared by Se and comparative examples 1-3; Figure 2 Pb in Examples 1-6 of this invention 1-x (AlSb) x Conductivity graphs of Se and the samples prepared in Comparative Examples 1-3 as a function of temperature; Figure 3 Pb in Examples 1-6 of this invention 1-x (AlSb) xSeebeck coefficient plots of Se and the samples prepared in Comparative Examples 1-3 as a function of temperature; Figure 4 Pb in Examples 1-6 of this invention 1-x (AlSb) x Thermal conductivity diagrams of Se and the samples prepared in Comparative Examples 1-3 as a function of temperature; Figure 5 Pb in Examples 1-6 of this invention 1-x (AlSb) x Thermoelectric figure of merit diagrams of Se and the samples prepared in Comparative Examples 1-3 as a function of temperature; Figure 6 The SEM image and surface scan EDS spectrum of the sample prepared in Example 3 of this invention are shown. Detailed Implementation

[0014] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention. Unless otherwise stated, the raw materials and reagents used in the following embodiments are commercially available products or can be prepared by known methods.

[0015] Prepare the raw materials: elemental Pb, Al, Sb, and Se. The purity of the Pb strips is 99.99% (Beijing Haoke Technology Co., Ltd.), the purity of the Al particles is 99.99% (Hebei Luohong Technology Co., Ltd.), the purity of the Sb particles is 99.99% (Hebei Luohong Technology Co., Ltd.), and the purity of the Se particles is 99.99% (Hebei Luohong Technology Co., Ltd.). Unless otherwise specified, all reagents and instruments used can be obtained commercially. Example 1

[0016] 1) According to Pb 0.9975 (AlSb) 0.0025 The stoichiometric ratio of elements Pb, Al, Sb and Se in Se is weighed and poured into a quartz tube. After evacuation, the quartz tube is sealed with an oxyhydrogen flame. 2) The flame-sealed vacuum quartz tube from step 1) was placed in a muffle furnace for melting reaction. The furnace temperature was increased from room temperature to 1000℃ at a rate of 100℃ / h. After holding at 1000℃ for 6 hours, it was cooled to room temperature to obtain Pb. 0.9975 (AlSb) 0.0025 Se material precursors; 3) The Pb obtained from the reaction in step 2) 0.9975 (AlSb) 0.0025Se material was ground into powder, and the resulting powder was filled into a graphite mold for sintering. The axial pressure was 30 MPa, and the temperature was increased to 600 °C at a rate of 60 °C / min. The sintering time was 15 min to obtain PbSe bulk material, which was then sliced ​​to obtain n-type Pb. 0.9975 (AlSb) 0.0025 Se thermoelectric materials. Example 2

[0017] According to Pb 0.997 (AlSb) 0.003 The stoichiometric ratio of Se was determined by weighing out elemental Pb, Al, Sb, and Se, and the remaining experimental steps were the same as in Example 1. Example 3

[0018] According to Pb 0.9965 (AlSb) 0.0035 The stoichiometric ratio of Se was determined by weighing out elemental Pb, Al, Sb, and Se, and the remaining experimental steps were the same as in Example 1. Example 4

[0019] According to Pb 0.996 (AlSb) 0.004 The stoichiometric ratio of Se was determined by weighing out elemental Pb, Al, Sb, and Se, and the remaining experimental steps were the same as in Example 1. Example 5

[0020] According to Pb 0.9955 (AlSb) 0.0045 The stoichiometric ratio of Se was determined by weighing out elemental Pb, Al, Sb, and Se, and the remaining experimental steps were the same as in Example 1. Example 6

[0021] According to Pb 0.995 (AlSb) 0.005 The stoichiometric ratio of Se was determined by weighing out elemental Pb, Al, Sb, and Se, and the remaining experimental steps were the same as in Example 1. Example 7

[0022] According to Pb 0.994 (AlSb) 0.006 The stoichiometric ratio of Se was determined by weighing out elemental Pb, Al, Sb, and Se, and the remaining experimental steps were the same as in Example 1. Example 8

[0023] 1) According to Pb 0.9965 (AlSb) 0.0035 The stoichiometric ratio of elements Pb, Al, Sb and Se in Se is weighed and poured into a quartz tube. After evacuation, the quartz tube is sealed with an oxyhydrogen flame. 2) The flame-sealed vacuum quartz tube from step 1) was placed in a muffle furnace for melting reaction. The furnace temperature was increased from room temperature to 1200℃ at a heating rate of 80℃ / h. After holding at 1200℃ for 4 hours, it was cooled to room temperature to obtain Pb. 0.9965 (AlSb) 0.0035 Se material precursors; 3) The Pb obtained from the reaction in step 2) 0.9965 (AlSb) 0.0035 Se material was ground into powder, and the resulting powder was filled into a graphite mold for sintering. The axial pressure was 35 MPa, the temperature was increased to 600 °C at a rate of 50 °C / min, and the sintering time was 10 min to obtain Pb. 0.9965 (AlSb) 0.0035 Se bulk material, sliced ​​to obtain n-type Pb 0.9965 (AlSb) 0.0035 Se thermoelectric materials. Example 9

[0024] 1) According to Pb 0.9965 (AlSb) 0.0035 The stoichiometric ratio of elements Pb, Al, Sb and Se in Se is weighed and poured into a quartz tube. After evacuation, the quartz tube is sealed with an oxyhydrogen flame. 2) The flame-sealed vacuum quartz tube from step 1) was placed in a muffle furnace for melting reaction. The furnace temperature was increased from room temperature to 1050℃ at a heating rate of 100℃ / h. After holding at 1050℃ for 4 hours, it was cooled to room temperature to obtain Pb. 0.9965 (AlSb) 0.0035 Se material precursors; 3) The Pb obtained from the reaction in step 2) 0.9965 (AlSb) 0.0035 Se material was ground into powder, and the resulting powder was filled into a graphite mold for sintering. The axial pressure was 40 MPa, and the temperature was increased to 500 °C at a heating rate of 80 °C / min. The sintering time was 5 min to obtain Pb. 0.9965 (AlSb) 0.0035 Se bulk material, sliced ​​to obtain n-type Pb 0.9965 (AlSb) 0.0035 Se thermoelectric materials. Example 10

[0025] 1) According to Pb 0.9965 (AlSb) 0.0035 The stoichiometric ratio of elements Pb, Al, Sb and Se in Se is weighed and poured into a quartz tube. After evacuation, the quartz tube is sealed with an oxyhydrogen flame. 2) The flame-sealed vacuum quartz tube from step 1) was placed in a muffle furnace for melting reaction. The furnace temperature was increased from room temperature to 1000℃ at a heating rate of 85℃ / h. After holding at 1000℃ for 4 hours, it was cooled to room temperature to obtain Pb. 0.9965 (AlSb) 0.0035 Se material precursors; 3) The Pb obtained from the reaction in step 2) 0.9965 (AlSb) 0.0035 Se material was ground into powder, and the resulting powder was filled into a graphite mold for sintering. The axial pressure was 38 MPa, and the temperature was increased to 500 °C at a heating rate of 100 °C / min. The sintering time was 10 min to obtain Pb. 0.9965 (AlSb) 0.0035 Se bulk material, sliced, to obtain n-type Pb 0.9965 (AlSb) 0.0035 Se thermoelectric materials. Example 11

[0026] 1) According to Pb 0.9965 (AlSb) 0.0035 The stoichiometric ratio of elements Pb, Al, Sb and Se in Se is weighed and poured into a quartz tube. After evacuation, the quartz tube is sealed with an oxyhydrogen flame. 2) The vacuum quartz tube sealed in step 1) was placed in a muffle furnace for melting reaction. The furnace temperature was increased from room temperature to 1200℃ at a heating rate of 90℃ / h. After holding at 1200℃ for 3h, it was cooled to room temperature to obtain Pb. 0.9965 (AlSb) 0.0035 Se material precursors; 3) The Pb obtained from the reaction in step 2) 0.9965 (AlSb) 0.0035 Se material was ground into powder, and the resulting powder was filled into a graphite mold for sintering. The axial pressure was 33 MPa, and the temperature was increased to 500℃ at a heating rate of 50℃ / h. The sintering time was 8 min to obtain Pb. 0.9965 (AlSb) 0.0035 Se bulk material, sliced ​​to obtain n-type Pb 0.9965 (AlSb) 0.0035 Se thermoelectric materials. Example 12

[0027] 1) According to Pb 0.996 (AlSb) 0.004 The stoichiometric ratio of elements Pb, Al, Sb and Se in Se is weighed and poured into a quartz tube. After evacuation, the quartz tube is sealed with an oxyhydrogen flame. 2) The flame-sealed vacuum quartz tube from step 1) was placed in a muffle furnace for melting reaction. The furnace temperature was increased from room temperature to 1150℃ at a heating rate of 90℃ / h. After holding at 1150℃ for 4 hours, it was cooled to room temperature to obtain Pb. 0.996 (AlSb) 0.004 Se material precursors; 3) The Pb obtained from the reaction in step 2) 0.996 (AlSb) 0.004 Se material was ground into powder, and the resulting powder was filled into a graphite mold for sintering. The axial pressure was 30 MPa, and the temperature was increased to 550 °C at a heating rate of 55 °C / h. The sintering time was 10 min to obtain Pb. 0.996 (AlSb) 0.004 Se bulk material, sliced ​​to obtain n-type Pb 0.996 (AlSb) 0.004 Se thermoelectric materials. Example 13

[0028] 1) According to Pb 0.997 (AlSb) 0.003 The stoichiometric ratio of elements Pb, Al, Sb and Se in Se is weighed and poured into a quartz tube. After evacuation, the quartz tube is sealed with an oxyhydrogen flame. 2) The flame-sealed vacuum quartz tube from step 1) was placed in a muffle furnace for melting reaction. The furnace temperature was increased from room temperature to 1050℃ at a heating rate of 90℃ / h. After holding at 1050℃ for 5h, it was cooled to room temperature to obtain Pb. 0.997 (AlSb) 0.003 Se material precursors; 3) The Pb obtained from the reaction in step 2) 0.997 (AlSb) 0.003 Se material was ground into powder, and the resulting powder was filled into a graphite mold for sintering. The axial pressure was 35 MPa, and the temperature was increased to 600 °C at a heating rate of 100 °C / h. The sintering time was 12.5 min to obtain Pb. 0.997 (AlSb) 0.003 Se bulk material, sliced ​​to obtain n-type Pb 0.997 (AlSb) 0.003 Se thermoelectric materials. Comparative Example 1

[0029] Compared with Example 1, the experimental steps are the same except that the elements Pb and Se are weighed according to the stoichiometric ratio in PbSe. Comparative Example 2

[0030] Compared with Example 1, except according to Pb 0.9975 Al 0.0025Except for weighing the elemental Pb, Al, and Se, the stoichiometric ratios in Se are the same for all other experimental procedures. Comparative Example 3

[0031] Compared with Example 1, except according to Pb 0.9975 Sb 0.0025 The stoichiometric ratio of Se in the experiment is the same except for the weighing of elemental Pb, Sb and Se. Comparative Example 4

[0032] Compared with Example 1, except according to Pb 0.9975 Al 0.0005 Sb 0.0025 The stoichiometric ratio of Se is the same as that of elemental Pb, Al, Sb and Se, except for the weighing of elemental Pb, Al and Sb. Comparative Example 5

[0033] Compared with Example 1, except according to Pb 0.9975 Al 0.0025 Sb 0.0005 The stoichiometric ratio of Se is the same as that of elemental Pb, Al, Sb and Se, except for the weighing of elemental Pb, Al and Sb. Performance Analysis:

[0034] 1) Comparative analysis of the crystal structures of the samples prepared in Examples 1-6 and Comparative Examples 1-3; the samples were ground into powder using an agate mortar and pestle, and powder X-ray diffraction analysis was performed. (See attached...) Figure 1 As shown, the test angle was 20-80 degrees. The X-ray diffraction peaks of all prepared samples were completely consistent with the lead selenide standard card. No diffraction peaks of other impurities were detected, which proves that the samples prepared by the method provided by this invention are all pure phase products. Figure 6 The Pb prepared in Example 3 is given. 0.9965 (AlSb) 0.0035 SEM characterization and EDS spectra of elemental distribution on the surface of the Se sample. The SEM image shows that the sample is sintered and dense with no obvious pores; the surface scan spectrum shows that Pb, Se, Al and Sb are uniformly distributed.

[0035] 2) The electrical properties of the samples prepared in Examples 1-6 and Comparative Examples 1-3 were tested using the CTA-3S thermoelectric material testing system from Beijing Creo Technology Co., Ltd. The relationship between conductivity and Seebeck coefficient as a function of temperature is shown in the attached figure. Figure 2 and attached Figure 3 As shown, the electrical conductivity of the prepared material decreases with increasing temperature. The conductivity increases with increasing AlSb dual-element doping content, but decreases again after reaching a certain level. Example 3 obtained n-type Pb... 0.9965 (AlSb) 0.0035Se has the highest electrical conductivity, which also indicates that an appropriate AlSb dual-element doping amount can effectively enhance Pb. 1-x (AlSb) x Electrical conductivity of Se materials.

[0036] 3) The thermal diffusivity of the materials prepared in Examples 1-6 was measured using a Netzsch LFA467 laser flare thermal conductivity meter. D Tests were conducted, and the thermal conductivity was measured. κ = C p Dρ The density was calculated. ρ Specific heat was obtained through Archimedes' method. C p The thermal conductivity was calculated using the Dulong-Petty formula. Table 1 shows the relationship between thermal conductivity and temperature, and Pb... 1-x (AlSb) x The thermal conductivity of Se materials at 923 K first decreases and then increases with the increase of AlSb dual-element doping content.

[0037] 4) Figure 5 The thermoelectric figure of merit diagrams of the samples prepared in Examples 1-6 and Comparative Examples 1-3 of this invention are shown as a function of temperature. (See attached diagram.) Figure 5 As shown, AlSb dual-element doping at low temperatures affects Pb. 1-x (AlSb) x The thermoelectric figure of merit of Se materials shows a relatively small increase, but the increase becomes more significant with increasing temperature. At 923 K, Pb... 1-x (AlSb) x The thermal conductivity of Se materials first increases and then slowly decreases with increasing AlSb dual-element doping content. As shown in the figure, the Pb materials prepared in Examples 1-6... 0.9975 (AlSb) 0.0025 Se, Pb 0.997 (AlSb) 0.003 Se, Pb 0.9965 (AlSb) 0.0035 Se, Pb 0.996 (AlSb) 0.004 Se, Pb 0.9955 (AlSb) 0.0045 Se and Pb 0.995 (AlSb) 0.005 The thermoelectric figure of merit (ZT) of Se were 1.21, 1.40, 1.65, 1.53, 1.47 and 1.37, respectively; the PbSe and Pb prepared in Comparative Examples 1-5 0.998 Al 0.002 Se and Pb 0.998 Sb 0.002 Se, Pb0.997 Al 0.0005 Sb 0.0025 Se and Pb 0.997 Al 0.0025 Sb 0.0005 The thermoelectric figure of merit (ZT) of Se were 0.54, 0.82, 0.94, 1.04, and 0.97, respectively; further demonstrating the improvement of the thermoelectric figure of merit of the thermoelectric material by equimolar AlSb dual-element doping. The present invention modifies the remaining process conditions to prepare Pb in Examples 8-13. 1-x (AlSb) x The thermoelectric figure of merit (ZT) of Se materials are 1.64, 1.63, 1.66, 1.65, 1.52 and 1.42, respectively, further demonstrating that AlSb dual-element doping can effectively enhance the performance of Pb. 1-x (AlSb) x Thermoelectric figure of merit of Se materials; n-type Pb prepared in this patent 0.9965 (AlSb) 0.0035 Se exhibits the greatest thermoelectric figure of merit at 923 K.

[0038]

[0039] Table 1 shows the electrical conductivity, thermal conductivity, and thermoelectric figure of merit (ZT) of thermoelectric materials doped with different amounts of Al and Sb at 923 K. As can be seen from Table 1, with the increase of Al and Sb doping amounts, the thermal conductivity and electrical conductivity of the thermoelectric materials first decrease and then increase. When Pb... 1-x (AlSb) x In Se thermoelectric materials, the thermal and electrical conductivity reach their lowest levels when the Al and Sb doping concentrations are 0.0035. The synergistic effect of co-doping of the two elements not only introduces dislocations to reduce lattice thermal conductivity but also increases carrier concentration. For Pb, the Al and Sb doping concentrations are between 0.0025 and 0.006. 1-x (AlSb) x The thermoelectric figure of merit (ZT) of Se thermoelectric materials has been effectively improved, while that of Pb has been significantly enhanced. 0.9965 (AlSb) 0.0035 The thermoelectric figure of merit (ZT) of Se reached 1.65. By comparing the thermal conductivity, electrical conductivity, and ZT of the thermoelectric materials prepared in the examples and comparative examples, it can be found that the ZT of the thermoelectric materials prepared by equimolar doping of Al and Sb is higher than that of the undoped and non-equimolar doped thermoelectric materials. This further illustrates that only equimolar doping can better optimize dislocation and carrier concentration. The ZT of the thermoelectric materials prepared by equimolar doping of Al and Sb is increased by as much as 124-205% compared to the undoped thermoelectric materials, and by 30-100% compared to the non-equimolar doped thermoelectric materials.

[0040] The above description is merely a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. An n-type lead selenide thermoelectric material, characterized by: The n-type lead selenide thermoelectric material has a chemical formula of Pb 1-x (AlSb) x Se; wherein 0.0025≤x≤0.

006.

2. A method of producing an n-type lead selenide thermoelectric material as claimed in claim 1, characterized in that, The method comprises the following steps: (1) According to the chemical formula Pb 1-x (AlSb) x Se, stoichiometric ratio of the elements Pb, Al, Sb and Se in the range of 0.0025≤x≤0.006 is taken, mixed and vacuum heated for melting reaction to prepare Pb 1-x (AlSb) x Se material precursor; (2) Pb 1-x (AlSb) x The n-type lead selenide thermoelectric material is obtained by grinding, sintering into a block and slicing the Se material precursor; the sintering into a block is performed at a temperature increasing rate of 50-100 ℃ / min to 500-600 ℃, and the temperature is kept for 5-15 min; the sintering pressure is 30-40 MPa.

3. The method of claim 2, wherein the n-type PbSe thermoelectric material is prepared by a process comprising: In the step (1), the melting reaction is heated to 1000-1200 ℃ at a heating rate of 80-100 ℃ / h, and kept for 3-6 h.

4. Use of an n-type lead selenide thermoelectric material as defined in claim 1 or produced by the method of claim 2 or 3 in a thermoelectric conversion device.

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