Novel thermoelectric material based on N-type BiSbSe3 polycrystal and preparation method thereof

Abstract

The invention discloses a novel thermoelectric material based on N-type BiSbSe3 polycrystal and a preparation method thereof, and belongs to the technical field of thermoelectric material preparation, the thermoelectric material is S solid solution and halogen doped N-type BiSbSe3 polycrystal, the chemical general formula of the thermoelectric material is BiSbSe3-x-y SxMy, M is one of Br, Cl and I, the molar ratio of Bi to Sb to Se to S to M is 1: 1: 3-x-y: x: y, x is greater than or equal to 0.12 and less than or equal to 0.48, and y is greater than or equal to 0 and less than or equal to 0.06. The preparation method comprises the following steps: (1) weighing required raw materials including a Bi elementary substance, a Sb elementary substance, a Se elementary substance, Bi2S3 and a halogen introducing substance, ensuring that the molar ratio of Bi to Sb to Se to S to M is 1: 1: (3-x-y): x: y, M is Br or Cl or I, x is more than or equal to 0.12 and less than or equal to 0.48, y is more than or equal to 0 and less than or equal to 0.06, and mixing the raw materials after weighing; and (2) carrying out high-temperature melting synthesis reaction on the mixed raw materials, and cooling along with a furnace after the reaction is finished, so as to finally obtain the N-type BiSbSe3 polycrystal. The problems that in the prior art, when BiSbSe3 is prepared, a quenching technology is needed for assistance, energy consumption is large, time is long, and part of media are low in safety and not environmentally friendly are solved.

Description

Technical Field

[0001] This invention belongs to the field of thermoelectric material preparation technology, specifically relating to a novel thermoelectric material based on N-type BiSbSe3 polycrystalline and its preparation method. Background Technology

[0002] As the core foundation of thermoelectric devices, the performance optimization of thermoelectric materials requires consideration of multiple requirements: industrial applications necessitate controllable raw material costs, while wearable applications require non-toxic components and good environmental stability. Simultaneously, efficient energy conversion demands high thermoelectric figure of merit (ZT) across a wide temperature range. To date, researchers have developed high-performance Bi₂Te₃ systems through strategies such as full-scale defect structure manipulation, band degeneracy, and energy level resonance. However, these materials are all limited by their tellurium (Te) content—extremely low abundance in the Earth's crust (approximately 0.001-0.005 ppm, comparable to platinum)—resulting in high raw material costs. Therefore, developing novel Te-free, high-performance thermoelectric material systems that can replace Bi₂Te₃ while possessing low cost, environmental friendliness, and high performance across a wide temperature range has become a key breakthrough direction for driving the innovation of thermoelectric power generation technology.

[0003] Bi₂Se₃, a sister material to Bi₂Te₃, is a three-dimensional topological insulator. Its raw material, Se, is more abundant and less expensive than Te, and its polycrystalline structure and band gap are similar to Bi₂Te₃, making it a potential substitute for Bi₂Te₃. However, its lower power factor and higher thermal conductivity limit its ZT value. In adjusting the band structure of Bi₂Se₃ using Sb, it was found that an orthorhombic phase, BiSbSe₃, was obtained when the substitution amount reached 50%. Current research shows that BiSbSe₃ exhibits a chain-like atomic arrangement, with Bi and Sb atoms alternating to form the framework, and Se atoms filling the interstitial spaces, forming a unique combination of octahedral and trigonal pyramidal tetrahedral structures. BiSbSe₃ exhibits a lower lattice thermal conductivity than Bi₂Se₃, as low as 0.58 W / m² at room temperature. -1 k -1 It is currently known that the preparation of BiSbSe3 requires a quenching process; otherwise, BiSbSe3 will undergo phase separation under slow cooling, resulting in a mixed phase of orthorhombic and rhombohedral phases. However, the quenching process is energy-intensive and time-consuming, and some media pose safety and environmental issues, as well as challenges to the reproducibility of performance experiments. Summary of the Invention

[0004] The purpose of this invention is to provide a novel thermoelectric material based on N-type BiSbSe3 polycrystalline material and its preparation method, which solves the problems of high energy consumption, long preparation time, low safety and environmental unfriendliness of some media when preparing BiSbSe3 by existing technology.

[0005] A novel thermoelectric material based on N-type BiSbSe3 polycrystalline material, wherein the thermoelectric material is an N-type BiSbSe3 polycrystalline material with S solid solution and halogen doping, and the general chemical formula of the thermoelectric material is BiSbSe3. 3-x-y S x M y M is one of Br, Cl, and I, and the molar ratio of Bi:Sb:Se:S:M is 1:1:3-xy:x:y, where 0.12 ≤ x ≤ 0.48 and 0 ≤ y ≤ 0.06.

[0006] A method for preparing a novel thermoelectric material based on N-type BiSbSe3 polycrystalline material includes the following steps: (1) Weigh the required raw materials Bi, Sb, Se, Bi2S3, and halogen introducer to ensure that the molar ratio of Bi:Sb:Se:S:M is 1:1:3-xy:x:y, where M is Br, Cl, or I, 0.12 ≤ x ≤ 0.48, 0 ≤ y ≤ 0.06. When M is Cl, the halogen introducer is BiCl3; when M is Br, the halogen introducer is BiBr3; when M is I, the halogen introducer is I2. After weighing, mix the raw materials. (2) The mixed raw materials are subjected to high-temperature melting and synthesis reaction. After the reaction is completed, the furnace is cooled to finally obtain N-type BiSbSe3 polycrystalline.

[0007] Furthermore, in step (1), the purity of Bi, Sb, Se, and I2 is not less than 4N.

[0008] Further, step (2) specifically involves placing the mixed raw materials in a flat-bottomed quartz tube, and then... -3 The encapsulation was carried out under the Pa environment; the encapsulated flat-bottomed quartz tube was placed horizontally in a muffle furnace for high-temperature melting synthesis reaction. The reaction procedure was as follows: the muffle furnace was heated to 900℃ at a heating rate of 180℃ / h and held for 12h. After the holding period, the furnace was cooled to room temperature to obtain BiSbSe3 polycrystalline material.

[0009] Furthermore, the flat-bottomed quartz tube has an inner diameter of 11 mm, a wall thickness of 1 mm, and a height of 28 cm. Before use, the flat-bottomed quartz tube is cleaned with alcohol and deionized water.

[0010] In summary, due to the adoption of the above technical solution, the beneficial effects of the present invention are: 1. This invention provides a preparation technique for orthorhombic BiSbSe3 materials without quenching. The problem of phase separation in BiSbSe3 under slow cooling is solved by solid-solution with sulfur, resulting in thermodynamically stable orthorhombic BiSbSe3. Then, in the orthorhombic BiSbSe3 with minimal solid-solution sulfur content, halogen doping addresses the issues of decreased conductivity, increased Seebeck coefficient, decreased power factor, increased lattice thermal conductivity and total thermal conductivity, and decreased ZT value after S solid-solution, thus preparing a high-ZT BiSbSe3 polycrystalline thermoelectric material with a maximum thermoelectric figure of merit ZT ≥ 1.03.

[0011] 2. This invention does not require the development of new polycrystalline growth equipment, nor does it require modification of existing equipment, nor does it require additional adjustments and control to growth conditions and processes. Stable growth of orthorhombic polycrystalline material can be achieved simply by adjusting the composition of the material itself. Attached Figure Description

[0012] Figure 1 This is an XRD pattern of an N-type BiSbSe3 polycrystalline material provided in Embodiment 1 of the present invention; Figure 2 The graph shows the test results of the electrical conductivity (σ) of N-type BiSbSe3 polycrystalline materials provided in Examples 1 and 2 and Comparative Examples 1 and 2 as a function of temperature. Figure 3 The graph shows the test results of the Seebeck coefficient (S) of N-type BiSbSe3 polycrystalline materials as a function of temperature in Embodiments 1 and 2 and Comparative Examples 1 and 2 of the present invention. Figure 4 The power factor (PF) of N-type BiSbSe3 polycrystalline materials provided in Embodiments 1 and 2 and Comparative Examples 1 and 2 of this invention is a test result curve showing the change of power factor (PF) with temperature. Figure 5 The graph shows the test results of the thermoelectric figure of merit (ZT) of N-type BiSbSe3 polycrystalline materials as a function of temperature provided in Examples 1 and 2 and Comparative Examples 1 and 2 of the present invention. Detailed Implementation

[0013] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions in the embodiments of this invention are described clearly and completely below. Obviously, the described embodiments are only some, not all, of the embodiments of this invention. Furthermore, the specific embodiments described herein are only used to explain this invention and are not intended to limit this invention.

[0014] Example 1 Step 1: Using high-purity elemental Bi, Sb, Se, and the compound Bi₂S₃ as initial raw materials, weigh them in air to ensure the molar ratio of Bi:Sb:Se:S is 1:1:2.55:0.45. After mixing the raw materials, place them in a flat-bottomed quartz tube (height ~28cm, inner diameter ~11mm, tube wall thickness ~1mm), and evacuate to a vacuum degree ≤5×10⁻⁶. -4 After Pa, seal it.

[0015] Step 2: Place the sealed flat-bottomed quartz tube into a muffle furnace. First, raise the temperature of the muffle furnace to 900℃ at a rate of 180℃ / h, and maintain this temperature for 720 minutes to carry out the high-temperature melting synthesis reaction. Finally, cool the furnace. The final product is BiSbSe. 2.55 S 0.45 Polycrystalline.

[0016] Step 3: Obtain the BiSbSe 2.55 S 0.45 The polycrystalline material was ground in a mortar until it could pass through a 200-mesh sieve. Polycrystalline bulk materials were prepared by sintering using an SPS (spark plasma sintering furnace). A 10g sample was placed in a 12.7mm diameter mold and sintered at 40MPa pressure, 500℃, and a temperature higher than 1×10⁻⁶. -1 Sintering under Pa conditions to form a bulk material yields BiSbSe. 2.55 S 0.45 Polycrystalline bulk.

[0017] Example 2 Step 1: Using high-purity elemental Bi, Sb, Se, and compounds Bi₂S₃ and BiBr₃ as initial raw materials, weigh them in air to ensure the molar ratio of Bi:Sb:Se:S:Br is 1:1:2.52:0.45:0.03. Alternatively, using high-purity elemental Bi, Sb, Se, and compounds Bi₂S₃ and BiCl₃ as initial raw materials, weigh them in air to ensure the molar ratio of Bi:Sb:Se:S:Cl is 1:1:2.505:0.45:0.045. Alternatively, using high-purity elemental Bi, Sb, Se, I, and compounds Bi₂S₃ as initial raw materials, weigh them in air to ensure the molar ratio of Bi:Sb:Se:S:I is 1:1:2.52:0.45:0.03. After mixing the raw materials, place them in a flat-bottomed quartz tube (height ~28cm, inner diameter ~11mm, tube wall thickness ~1mm), and evacuate to a vacuum degree ≤5×10⁻⁶. -4 After Pa, seal it.

[0018] Step 2: Place the sealed flat-bottomed quartz tube into a muffle furnace. First, raise the temperature of the muffle furnace to 900℃ at a rate of 180℃ / h, and maintain this temperature for 720 minutes to carry out the high-temperature melting synthesis reaction. Finally, cool the furnace. The final product is BiSbSe.2.52 S 0.45 Br 0.03 Polycrystalline or BiSbSe 2.505 S 0.45 Cl 0.045 Polycrystalline or BiSbSe 2.52 S 0.45 I 0.03 Polycrystalline.

[0019] Step 3: Obtain the BiSbSe 2.52 S 0.45 Br 0.03 Or BiSbSe 2.505 S 0.45 Cl 0.045 Or BiSbSe 2.52 S 0.45 I 0.03 The polycrystalline material was ground in a mortar until it could pass through a 200-mesh sieve. Polycrystalline bulk materials were prepared by sintering using an SPS (spark plasma sintering furnace). A 10g sample was placed in a 12.7mm diameter mold and sintered at 40MPa pressure, 500℃, and a temperature higher than 1×10⁻⁶. -1 Sintering under Pa conditions to form a bulk material yields BiSbSe. 2.52 S 0.45 Br 0.03 Or BiSbSe 2.505 S 0.45 Cl 0.045 Or BiSbSe 2.52 S 0.45 I 0.03 Polycrystalline bulk.

[0020] Comparative Example 1 Step 1: Using high-purity elemental Bi, Sb, and Se as initial raw materials, weigh them in air to ensure a molar ratio of Bi:Sb:Se of 1:1:3. After mixing, place the mixture into a flat-bottomed quartz tube (height ~28cm, inner diameter ~11mm, tube wall thickness ~1mm), and evacuate to a vacuum degree ≤5×10⁻⁶. -4 After Pa, seal it.

[0021] Step 2: Place the sealed flat-bottomed quartz tube into a muffle furnace. First, raise the temperature of the muffle furnace to 900℃ at a rate of 180℃ / h, and maintain this temperature for 720 minutes to carry out the high-temperature melting synthesis reaction. Finally, cool the furnace. The final product is BiSbSe3 polycrystalline material.

[0022] Step 3: Grind the obtained BiSbSe3 polycrystalline material in a mortar until it can pass through a 200-mesh sieve. Prepare a polycrystalline bulk by sintering using an SPS (spark plasma sintering furnace). Take 10g of sample and place it in a mold with a diameter of 12.7mm. Sinter at a pressure of 40MPa, 500℃, and a temperature higher than 1×10⁻⁶.-1 BiSbSe3 polycrystalline bulk material was obtained by sintering under Pa conditions.

[0023] Comparative Example 2 Step 1: Using high-purity elemental Bi, Sb, Se, and the compound Bi₂S₃ as initial raw materials, weigh them in air to ensure the molar ratio of Bi:Sb:Se:S is 1:1:2.55:0.45. After mixing, place the mixture into a flat-bottomed quartz tube (height ~28cm, inner diameter ~11mm, tube wall thickness ~1mm), and evacuate to a vacuum degree ≤5×10⁻⁶. -4 After Pa, seal it.

[0024] Step 2: Place the sealed flat-bottomed quartz tube into a muffle furnace. First, raise the temperature of the muffle furnace to 900℃ at a rate of 180℃ / h, and maintain this temperature for 720 minutes to carry out the high-temperature melting synthesis reaction. Finally, cool the furnace. The final product is BiSbSe. 2.55 S 0.45 Polycrystalline.

[0025] Step 3: Obtain the BiSbSe 2.55 S 0.45 The polycrystalline material was ground in a mortar until it could pass through a 200-mesh sieve. Polycrystalline bulk materials were prepared by sintering using an SPS (spark plasma sintering furnace). A 10g sample was placed in a 12.7mm diameter mold and sintered at 40MPa pressure, 500℃, and a temperature higher than 1×10⁻⁶. -1 Sintering under Pa conditions to form a bulk material yields BiSbSe. 2.55 S 0.45 Polycrystalline bulk.

[0026] The N-type BiSbSe3 polycrystalline bulk materials obtained in Examples 1 and 2 and Comparative Examples 1 and 2 were cut into regular cuboids (3*3*8cm). The samples were tested using a resistivity / Seebeck coefficient testing system and a laser thermal conductivity meter to obtain the conductivity (σ), Seebeck coefficient (S), power factor (PF), and thermoelectric figure of merit (ZT) to evaluate the electrical transport properties of the samples.

[0027] Figure 2 Test results of the electrical conductivity (σ) of N-type BiSbSe3 polycrystalline materials as a function of temperature for Examples 1 and 2 and Comparative Examples 1 and 2; Figure 3 Test results of the Seebeck coefficient (S) of N-type BiSbSe3 polycrystalline materials as a function of temperature for Examples 1 and 2 and Comparative Examples 1 and 2; Figure 4 Test results of power factor (PF) versus temperature for N-type BiSbSe3 polycrystalline materials provided in Examples 1 and 2 and Comparative Examples 1 and 2; Figure 5 Test results of the thermoelectric figure of merit (ZT) of N-type BiSbSe3 polycrystalline materials as a function of temperature for Examples 1 and 2 and Comparative Examples 1 and 2.

[0028] Depend on Figure 1 It is known that in the N-type S-solution BiSbSe3 polycrystalline material provided by the present invention, the introduction of S significantly improves the phase separation problem under slow cooling and achieves a stable orthorhombic phase state when at least 15% S is dissolved.

[0029] Depend on Figure 2-5 As can be seen from Example 1 and Comparative Example 1, the BiSbSe3 polycrystalline material after S solution exhibits a decrease in electrical conductivity, an increase in the Seebeck coefficient, a decrease in the power factor, and a decrease in the ZT value. From... Figure 2-5 As shown in Example 2 and Comparative Example 2, halogen doping significantly improves the thermoelectric performance. The significant improvement in electrical performance is mainly attributed to the increased carrier concentration due to halogen doping, which simultaneously activates multiple conduction bands to participate in electrical transport, resulting in increased effective mass and thus optimizing the power factor. Furthermore, the material itself possesses low thermal conductivity, leading to a higher thermoelectric figure of merit. Figure 2-5 It can be seen that the maximum thermoelectric figure of merit ZT of the S solid solution and halogen-doped N-type BiSbSe3 polycrystalline material provided by the present invention is 1.03, which is 5 times higher than that of the intrinsic N-type BiSbSe3 polycrystalline sample, indicating that the N-type BiSbSe3 polycrystalline material provided by the present invention has development potential.

[0030] according to Figure 2-5 The thermoelectric transport properties of the high-performance N-type BiSbSe3 polycrystalline materials obtained in Examples 1 and 2 are shown in Table 1:

[0031] Table 1 The thermoelectric transport properties of the N-type BiSbSe3 polycrystalline materials provided by Comparative Examples 1 and 2 are shown in Table 2:

[0032] Table 2 The above description constitutes an embodiment of the present invention. The foregoing descriptions are preferred embodiments of the present invention. Unless there is a clear contradiction or a prerequisite for a particular preferred embodiment, the preferred embodiments can be arbitrarily combined and used. The embodiments and specific parameters described are merely for clearly illustrating the verification process of the invention and are not intended to limit the scope of patent protection of the present invention. The scope of patent protection of the present invention is still determined by its claims. Similarly, any equivalent structural changes made based on the content of the present invention's specification should also be included within the scope of protection of the present invention.

Claims

1. A novel thermoelectric material based on N-type BiSbSe3 polycrystalline material, characterized in that, The thermoelectric material is an N-type BiSbSe3 polycrystalline material with S solid solution and halogen doping, and the general chemical formula of the thermoelectric material is BiSbSe. 3-x-y S x M y M is one of Br, Cl, and I, and the molar ratio of Bi:Sb:Se:S:M is 1:1:3-xy:x:y, where 0.12 ≤ x ≤ 0.48 and 0 ≤ y ≤ 0.

06.

2. A method for preparing a novel thermoelectric material based on N-type BiSbSe3 polycrystalline material according to claim 1, characterized in that, Includes the following steps: (1) Weigh the required raw materials Bi, Sb, Se, Bi2S3, and halogen introducer to ensure that the molar ratio of Bi:Sb:Se:S:M is 1:1:3-xy:x:y, where M is Br, Cl, or I, 0.12 ≤ x ≤ 0.48, 0 ≤ y ≤ 0.

06. When M is Cl, the halogen introducer is BiCl3; when M is Br, the halogen introducer is BiBr3; when M is I, the halogen introducer is I2. Mix the raw materials after weighing. (2) The mixed raw materials are subjected to high-temperature melting and synthesis reaction. After the reaction is completed, the furnace is cooled to finally obtain N-type BiSbSe3 polycrystalline.

3. A novel thermoelectric material based on N-type BiSbSe3 polycrystalline material and its preparation method according to claim 1, characterized in that, In step (1), the purity of Bi, Sb, Se and I2 is not less than 4N.

4. A novel thermoelectric material based on N-type BiSbSe3 polycrystalline material and its preparation method according to claim 1, characterized in that, Step (2) specifically involves placing the mixed raw materials in a flat-bottomed quartz tube under a vacuum degree not exceeding 1×10⁻⁶. -3 The encapsulation was carried out under the Pa environment; the encapsulated flat-bottomed quartz tube was placed horizontally in a muffle furnace for high-temperature melting synthesis reaction. The reaction procedure was as follows: the muffle furnace was heated to 900℃ at a heating rate of 180℃ / h and held for 12h. After the holding period, the furnace was cooled to room temperature to obtain BiSbSe3 polycrystalline material.

5. A novel thermoelectric material based on N-type BiSbSe3 polycrystalline material and its preparation method according to claim 4, characterized in that, The flat-bottomed quartz tube has an inner diameter of 11 mm, a wall thickness of 1 mm, and a height of 28 cm. Before use, the flat-bottomed quartz tube is cleaned with alcohol and deionized water.

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