Novel thermoelectric material with Pavonite derived crystal structure and preparation method thereof

Abstract

The invention discloses a novel thermoelectric material with a Pavonite derived crystal structure and a preparation method of the novel thermoelectric material. The chemical formula of the novel thermoelectric material with the Pavonite derived crystal structure is PbSn < 3 > Bi < 4 > Sb < 6 > Se < 19 >; the crystal structure of the novel thermoelectric material with the Pavonite derived crystal structure is composed of a NaCl configuration layer with an adjustable thickness and a GeS configuration layer with an unadjustable thickness, and the NaCl configuration layer and the GeS configuration layer are connected through a shared Se atom. In the NaCl configuration layer, the twisted octahedrons formed by Pb / Sn-Se and Bi / Sb-Se are connected in a common edge manner; the GeS configuration layer is composed of two Sb-Se tetragonal pyramids, two Bi / Sb-Se tetragonal pyramids and two Pb / Sn-Se octahedrons; the method is easy to operate, a large amount of PbSn3Bi4Sb6Se19 with high phase purity can be obtained within a short time, and the ZT of the PbSn3Bi4Sb6Se19 can reach 0.34 under 773 K.

Description

Technical Field

[0001] The present invention belongs to the technical field of novel thermoelectric materials, and in particular relates to a novel thermoelectric material having a Pavonite-derived crystal structure and a preparation method thereof. Background Art

[0002] With socioeconomic development and intensified industrial activity, the consumption of fossil energy has increased dramatically. Human demand for these non-renewable fossil energies is rapidly increasing. However, this consumption also leads to environmental pollution and climate change, seriously endangering human health. Consequently, the depletion of traditional fossil energy and the resulting environmental problems have attracted global attention. Thermoelectric materials and related technologies play a crucial role as environmentally friendly renewable energy technologies. Through the thermoelectric effect, thermoelectric materials can directly convert electrical energy into thermal energy, significantly improving energy conversion efficiency. This technology holds great promise for applications in waste heat recovery, chip cooling, and infrared detectors.

[0003] Pavonite and its derivatives are three-dimensional structures composed of adjustable-thickness NaCl layers and non-adjustable-thickness GeS layers connected by shared anions. Pavonite and its derivatives possess high stability and low thermal conductivity, making them promising for thermoelectric applications. However, the number of Pavonite-derived crystal structures currently available for thermoelectric applications is limited. Therefore, the search for more high-performance thermoelectric materials with Pavonite-derived crystal structures is crucial. Summary of the Invention

[0004] To solve the above problems, the present invention proposes a new thermoelectric material with a Pavonite-derived crystal structure and a preparation method thereof. The method is simple to operate and can obtain a large amount of PbSn3Bi4Sb6Se with high phase purity in a short time. 19 , its ZT can reach 0.34 at 773K.

[0005] To achieve the above object, the present invention adopts the following technical solutions:

[0006] A novel thermoelectric material having a Pavonite-derived crystal structure, wherein the chemical formula of the novel thermoelectric material having a Pavonite-derived crystal structure is PbSn3Bi4Sb6Se 19; The crystal structure of the new thermoelectric material with a Pavonite-derived crystal structure is composed of a NaCl configuration layer with adjustable thickness and a GeS configuration layer with non-adjustable thickness, and the NaCl configuration layer and the GeS configuration layer are connected by shared Se atoms; in the NaCl configuration layer, the distorted octahedra composed of Pb / Sn-Se and Bi / Sb-Se are connected by sharing edges; the GeS configuration layer is composed of two Sb-Se tetrahedrons, two Bi / Sb-Se tetrahedrons and two Pb / Sn-Se octahedra.

[0007] Preferably, the number of diagonal octahedra in the NaCl configuration layer is 8.

[0008] Preferably, the crystal structure of the novel thermoelectric material having a Pavonite-derived crystal structure belongs to a monoclinic structure, and the space group is C2 / m; the unit cell parameters of the novel thermoelectric material having a Pavonite-derived crystal structure are α=γ=90°,β=130.683°,Z=2,unit cell volume Theoretical density of crystal ρ cal =6.490g / cm 3 .

[0009] A method for preparing a novel thermoelectric material having a Pavonite-derived crystal structure comprises the following steps:

[0010] S1. Weighing: Prepare raw materials Pb bars, Sn particles, Bi particles, Sb blocks and Se particles, weigh them according to the molar ratio of Pb:Sn:Bi:Sb:Se=5:5:9:9:37 and mix them evenly;

[0011] S2, vacuum sealing: put the raw materials weighed in step S1 into a quartz tube with an inner diameter of 10 mm, and use a mechanical pump to pump the air pressure in the quartz tube to <10 -3 After Pa, the sealing process is carried out with an oxyhydrogen flame gun;

[0012] S3. High-temperature solid-phase reaction: placing the quartz tube sealed in step S2 into a box-type muffle furnace for high-temperature solid-phase reaction to obtain a single crystal sample.

[0013] A method for preparing a novel thermoelectric material having a Pavonite-derived crystal structure comprises the following steps:

[0014] S1. Weighing: Prepare raw materials Pb bars, Sn particles, Bi particles, Sb blocks and Se particles, weigh them according to the molar ratio of Pb:Sn:Bi:Sb:Se=1:3:4:6:19 and mix them evenly;

[0015] S2, vacuum sealing: put the raw materials weighed in step S1 into a quartz tube with an inner diameter of 13 mm, and use a mechanical pump to pump the air pressure in the quartz tube to <10 -3 After Pa, the sealing process is carried out with an oxyhydrogen flame gun;

[0016] S3, high temperature smelting: placing the quartz tube sealed in step S2 into a box-type muffle furnace for high temperature smelting and water quenching to obtain an ingot;

[0017] S4, grinding: placing the ingot obtained in step S3 into an agate mortar and grinding it thoroughly;

[0018] S5, spark plasma sintering: the mixed powder obtained in step S4 is placed into a graphite mold with a diameter of φ12.7 mm and subjected to spark plasma sintering to obtain PbSn3Bi4Sb6Se with a density of >95%. 19 Block.

[0019] Preferably, in step S3, the specific process of the high-temperature solid-phase reaction is: in a box-type muffle furnace, heating from room temperature to 850°C over 780 minutes, keeping at 850°C for 2880 minutes, and then cooling to room temperature over 2880 minutes to obtain a single crystal sample.

[0020] Preferably, in step S3, the specific process of high temperature smelting and water quenching is: in a box-type muffle furnace, the temperature is raised from room temperature to 1000°C over 20 hours, and then kept at 1000°C for 20 hours, and then water quenched to cool it down to obtain PbSn3Bi4Sb6Se 19 Ingot.

[0021] Preferably, in step S5, the specific process of the spark plasma sintering is: heating from room temperature to 400°C over 5 minutes, heating from 400°C to 450°C over 2 minutes, keeping at 450°C for 5 minutes, and then cooling to room temperature under a vacuum environment. During the sintering process, the axial pressure is maintained at 40 MPa.

[0022] After adopting the above technical solution, the present invention has the following beneficial effects:

[0023] 1. The present invention utilizes the characteristics of its NaCl configuration layer that can change its thickness and a large number of elements that can be replaced to construct a new thermoelectric material PbSn3Bi4Sb6Se with a Pavonite-derived crystal structure. 19 .

[0024] 2. The present invention adopts a high temperature smelting method to prepare a new thermoelectric material PbSn3Bi4Sb6Se with a Pavonite-derived crystal structure 19 The method is simple to prepare, the raw materials are cheap, and a large amount of products with high phase purity can be prepared in a short time.

[0025] 3. The present invention utilizes spark plasma sintering to quickly obtain a large amount of PbSn3Bi4Sb6Se with a density greater than 95%. 19 Thermoelectric materials.

[0026] 4. PbSn3Bi4Sb6Se obtained by the present invention 19 The power factor of the thermoelectric material can reach 1.99 μW cm at 773 K. -1 K -2 .

[0027] 5. PbSn3Bi4Sb6Se obtained by the present invention 19 The ZT of thermoelectric materials can reach 0.34 at 773K. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 Schematic diagram of the crystal structure of a new thermoelectric material with a Pavonite-derived crystal structure;

[0029] Figure 2 This is the powder X-ray diffraction pattern of a new thermoelectric material with a Pavonite-derived crystal structure;

[0030] Figure 3 This is the TG thermogravimetric test diagram of a new thermoelectric material with a Pavonite-derived crystal structure;

[0031] Figure 4 A graph showing the change in electrical conductivity of a new thermoelectric material having a Pavonite-derived crystal structure as a function of temperature;

[0032] Figure 5 This is a graph showing the Seebeck coefficient of a new thermoelectric material having a Pavonite-derived crystal structure as a function of temperature;

[0033] Figure 6 This is a graph showing the power factor of a new thermoelectric material with a Pavonite-derived crystal structure changing with temperature;

[0034] Figure 7 is a graph showing the total thermal conductivity of a new thermoelectric material having a Pavonite-derived crystal structure as a function of temperature;

[0035] Figure 8 A graph showing the change in lattice thermal conductivity of a new thermoelectric material having a Pavonite-derived crystal structure as a function of temperature;

[0036] Figure 9 This is a graph showing how the thermoelectric figure of merit of a new thermoelectric material with a Pavonite-derived crystal structure changes with temperature. DETAILED DESCRIPTION

[0037] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0038] Unless otherwise specified, the raw materials and reagents used in the following examples are commercially available or can be prepared by known methods.

[0039] Prepare raw materials: Pb bars, Sn pellets, Sb pellets, Bi pellets, and Se pellets. The purity of the Pb bars is 99.99% (Beijing Haoke Technology Co., Ltd.), the purity of the Sn pellets is 99.99% (Hebei Luohong Technology Co., Ltd.), the purity of the Sb pellets is 99.99% (Beijing Haoke Technology Co., Ltd.), the purity of the Bi pellets is 99.99% (Hebei Luohong Technology Co., Ltd.), and the purity of the Se pellets is 99.99% (Hebei Luohong Technology Co., Ltd.).

[0040] like Figures 1 to 9 shown.

[0041] Example 1

[0042] A PbSn3Bi4Sb6Se 19 A method for preparing a single crystal of a thermoelectric material comprises the following steps:

[0043] S1. Weighing: Prepare raw materials Pb bars, Sn particles, Bi particles, Sb blocks and Se particles, weigh them according to the molar ratio of Pb:Sn:Bi:Sb:Se=5:5:9:9:37 and mix them evenly;

[0044] S2, vacuum sealing: put the raw materials weighed in step S1 into a quartz tube with an inner diameter of 10 mm, and use a mechanical pump to pump the air pressure in the quartz tube to <10 -3 After Pa, the sealing process is carried out with an oxyhydrogen flame gun;

[0045] S3, high temperature solid phase reaction: the quartz tube sealed in step S2 is placed in a box-type muffle furnace for high temperature solid phase reaction; the specific process of the high temperature solid phase reaction is: in the box-type muffle furnace, the temperature is raised from room temperature to 850°C over 780 minutes, kept at 850°C for 2880 minutes, and then cooled to room temperature over 2880 minutes to obtain PbSn3Bi4Sb6Se 19 Single crystals of thermoelectric materials.

[0046] Example 2

[0047] A PbSn3Bi4Sb6Se 19 A method for preparing polycrystalline thermoelectric materials comprises the following steps:

[0048] S1. Weighing: Weigh Pb bars, Sn particles, Bi particles, Sb blocks, and Se particles according to the molar ratio of Pb:Sn:Bi:Sb:Se=1:3:4:6:19;

[0049] S2, vacuum sealing: put the raw materials weighed in step S1 into a quartz tube with an inner diameter of 13 mm, and use a mechanical pump to pump the air pressure in the quartz tube to <10 -3 After Pa, the sealing process is carried out with an oxyhydrogen flame gun;

[0050] S3, high temperature smelting: the quartz tube sealed in step S2 is placed in a box-type muffle furnace for high temperature smelting and water quenching; the specific process of high temperature smelting and water quenching is: in the box-type muffle furnace, the temperature is raised from room temperature to 1000°C over 20 hours, kept at 1000°C for 20 hours, and then water quenched to cool it down to obtain PbSn3Bi4Sb6Se 19 ingot;

[0051] S4, grinding: the ingot obtained in step S3 is placed in an agate mortar and ground for 15-20 minutes to fully mix;

[0052] S5, spark plasma sintering: the mixed powder obtained in step S4 is placed in a graphite mold with a diameter of φ12.7 mm for spark plasma sintering; the specific process of the spark plasma sintering is: heating from room temperature to 400°C for 5 minutes, heating from 400°C to 450°C for 2 minutes, keeping at 450°C for 5 minutes, and then cooling to room temperature under vacuum environment. During the sintering process, the axial pressure is maintained at 40 MPa, and finally a PbSn3Bi4Sb6Se with a density of >95% is obtained. 19 Cylindrical block.

[0053] The new thermoelectric material PbSn3Bi4Sb6Se with Pavonite-derived crystal structure prepared in Example 1 19 The crystal structure of the new thermoelectric material PbSn3Bi4Sb6Se with Pavonite-derived crystal structure was obtained by collecting data from a single crystal diffractometer and analyzing it with OLEX2.5. 19 The crystal structure is monoclinic, the space group is C2 / m, PbSn3Bi4Sb6Se 19 The unit cell parameters are α=γ=90°,β=130.683°,Z=2,the volume of the crystal is The theoretical density of a crystal is ρ cal =6.490g / cm 3 .

[0054] Performance testing:

[0055] (1) Weigh the polycrystalline PbSn3Bi4Sb6Se prepared in Example 2 19 About 0.5 g of the sample was ground into a powder using an agate mortar and subjected to powder X-ray diffraction analysis. The X-ray diffraction peaks of the prepared sample corresponded well to the theoretical diffraction peaks, e.g. Figure 2 shown.

[0056] (2) Weigh the polycrystalline PbSn3Bi4Sb6Se prepared in Example 2 19 About 5-15 mg of the sample was ground into a powder using an agate mortar. The thermal stability of the thermoelectric material prepared in Example 2 was tested using a thermal analyzer from NETZSCH, Germany. The prepared sample had almost no mass loss at 300-900 K, and a small amount of mass loss after 900 K, indicating that the thermoelectric material had good thermal stability. Figure 3 shown.

[0057] (3) The electrical properties of the thermoelectric material prepared in Example 2 were tested using the thermoelectric material testing system CTA-3S of Beijing Coreo Technology Co., Ltd. to obtain the relationship between the conductivity and the Seebeck coefficient as a function of temperature, as shown in FIG. Figure 4 and Figure 5 As shown. Due to the anisotropy of the sample, the conductivity perpendicular to the SPS direction is better than the conductivity parallel to the SPS direction. 19 The conductivity perpendicular to the SPS direction at 773K is 51.76S / cm. The power factor (PF) is calculated by the formula PF = σS 2 The relationship between power factor and temperature is as follows: Figure 6 As shown, PbSn3Bi4Sb6Se 19 The power factor perpendicular to the SPS direction is 1.99 μW cm at 773 K. -1 K -2 .

[0058] (4) The thermal diffusion coefficient D of the thermoelectric material prepared in Example 2 was tested using a laser flash thermal conductivity meter LFA467 from NETZSCH, Germany. The total thermal conductivity is expressed by the formula κ tot =C P Dρ is calculated. Density ρ is obtained by Archimedes drainage method, and specific heat C P The relationship between total thermal conductivity and temperature is calculated by the Dulongberti formula, as shown in the figure below: Figure 7 As shown. Electronic thermal conductivity (κ ele ) through κ ele = LσT. Lattice thermal conductivity (κ lat ) = total thermal conductivity (κ tot )-electronic thermal conductivity (κele ), the relationship between lattice thermal conductivity and temperature is shown in the figure Figure 8 As shown. PbSn3Bi4Sb6Se 19 The lattice thermal conductivity parallel to the SPS direction at 773K is 0.35 Wm -1 K -1 .

[0059] (5) Thermoelectric figure of merit (ZT) is calculated by the formula ZT = σS 2 T / κ tot The curve of thermoelectric figure of merit changing with temperature is as follows: Figure 9 As shown. PbSn3Bi4Sb6Se 19 The thermoelectric figure of merit perpendicular to the SPS direction is 0.34 at 773K, and the thermoelectric figure of merit parallel to the SPS direction (PA) is 0.25.

[0060] 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 changes or substitutions that can be easily conceived by a person skilled in the art within the technical scope disclosed in the present invention should be included in the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be based on the scope of protection of the claims.

Claims

1. A novel thermoelectric material having a Pavonite-derived crystal structure, characterized in that: The chemical formula of the novel thermoelectric material having a Pavonite-derived crystal structure is PbSn3Bi4Sb6Se 19 ; The crystal structure of the new thermoelectric material with a Pavonite-derived crystal structure is composed of a NaCl configuration layer with adjustable thickness and a GeS configuration layer with non-adjustable thickness, and the NaCl configuration layer and the GeS configuration layer are connected by shared Se atoms; in the NaCl configuration layer, the distorted octahedra composed of Pb / Sn-Se and Bi / Sb-Se are connected by sharing edges; the GeS configuration layer is composed of two Sb-Se tetrahedrons, two Bi / Sb-Se tetrahedrons and two Pb / Sn-Se octahedra.

2. The novel thermoelectric material having a Pavonite-derived crystal structure according to claim 1, characterized in that: The number of diagonal octahedra in the NaCl configuration layer is 8.

3. The novel thermoelectric material having a Pavonite-derived crystal structure according to claim 1, characterized in that: The crystal structure of the novel thermoelectric material having a Pavonite-derived crystal structure belongs to a monoclinic structure, and the space group is C2 / m. The unit cell parameters of the novel thermoelectric material having a Pavonite-derived crystal structure are: α=γ=90°,β=130.683°,Z=2,unit cell volume Theoretical density of crystal ρ cal =6.490g / cm 3 .

4. A method for preparing a novel thermoelectric material having a Pavonite-derived crystal structure according to any one of claims 1 to 3, characterized in that: The specific steps include: S1. Weighing: Prepare raw materials Pb bars, Sn particles, Bi particles, Sb blocks and Se particles, weigh them according to the molar ratio of Pb:Sn:Bi:Sb:Se=5:5:9:9:37 and mix them evenly; S2, vacuum sealing: put the raw materials weighed in step S1 into a quartz tube with an inner diameter of 10 mm, and use a mechanical pump to pump the air pressure in the quartz tube to <10 -3 After Pa, the sealing process is carried out with an oxyhydrogen flame gun; S3. High-temperature solid-phase reaction: placing the quartz tube sealed in step S2 into a box-type muffle furnace for high-temperature solid-phase reaction to obtain a single crystal sample.

5. A method for preparing a novel thermoelectric material having a Pavonite-derived crystal structure according to any one of claims 1 to 3, characterized in that: The specific steps include: S1. Weighing: Prepare raw materials Pb bars, Sn particles, Bi particles, Sb blocks and Se particles, weigh them according to the molar ratio of Pb:Sn:Bi:Sb:Se=1:3:4:6:19 and mix them evenly; S2, vacuum sealing: put the raw materials weighed in step S1 into a quartz tube with an inner diameter of 13 mm, and use a mechanical pump to pump the air pressure in the quartz tube to <10 -3 After Pa, the sealing process is carried out with an oxyhydrogen flame gun; S3, high temperature smelting: placing the quartz tube sealed in step S2 into a box-type muffle furnace for high temperature smelting and water quenching to obtain an ingot; S4, grinding: placing the ingot obtained in step S3 into an agate mortar and grinding it thoroughly; S5, spark plasma sintering: the mixed powder obtained in step S4 is placed into a graphite mold with a diameter of φ12.7 mm and subjected to spark plasma sintering to obtain PbSn3Bi4Sb6Se with a density of >95%. 19 Block.

6. The method for preparing a novel thermoelectric material having a Pavonite-derived crystal structure according to claim 4, wherein: In step S3, the specific process of the high-temperature solid-phase reaction is: in a box-type muffle furnace, the temperature is raised from room temperature to 850°C over 780 minutes, kept at 850°C for 2880 minutes, and then cooled to room temperature over 2880 minutes to obtain a single crystal sample.

7. The method for preparing a novel thermoelectric material having a Pavonite-derived crystal structure according to claim 5, wherein: In step S3, the specific process of high temperature smelting and water quenching is as follows: in a box-type muffle furnace, the temperature is raised from room temperature to 1000°C over 20 hours, and then kept at 1000°C for 20 hours, and then water quenched to cool it down to obtain PbSn3Bi4Sb6Se 19 Ingot.

8. The method for preparing a novel thermoelectric material having a Pavonite-derived crystal structure according to claim 5, wherein: In step S5, the specific process of the spark plasma sintering is: heating from room temperature to 400°C for 5 minutes, heating from 400°C to 450°C for 2 minutes, keeping at 450°C for 5 minutes, and then cooling to room temperature under vacuum environment. During the sintering process, the axial pressure is maintained at 40 MPa.

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