P-type bismuth telluride-based thermoelectric material and macro-scale preparation method thereof

Abstract

The application discloses a p-type bismuth telluride-based thermoelectric material and a macro preparation method thereof, and relates to the technical field of thermoelectric materials.The preparation method comprises the following steps: step one, according to the stoichiometric ratio of the p-type bismuth telluride-based thermoelectric material, Bi, Zn, Sb and Te are weighed respectively; step two, the weighed materials are put into a quartz tube for smelting to obtain smelted material ingots; step three, the smelted material ingots are ball milled by using a ball mill; and step four, the ball-milled powder is put into a graphite mold and subjected to spark plasma sintering to obtain the p-type bismuth telluride-based thermoelectric material.The application adopts the spark plasma sintering (SPS) technology to sinter, and dense thermoelectric materials can be sintered in a short time, time cost is saved, the thermoelectric performance of the sintered finished product is comparable to that of hot-press sintering, and the mass of the monolithic finished product can be up to 1000 g.The method can effectively improve production efficiency and save energy consumption.

Description

Technical Field

[0001] This application relates to the field of thermoelectric materials technology, and in particular to a p-type bismuth telluride-based thermoelectric material and its mass production method. Background Technology

[0002] Thermoelectric materials are a class of functional materials that achieve direct coupling and conversion of thermal energy and electrical energy through the Seebeck effect and Peltier effect of semiconductor materials. Due to their advantages such as being pollution-free, noise-free, small in size, long in life, and highly reliable, they are widely used in waste heat power generation, aerospace, military equipment, and household appliances.

[0003] Currently, commercial p-type Bi 2-x Sb x Te3 thermoelectric materials are mainly produced using hot pressing (HP) technology. This technology processes powdered or granular materials under high temperature, high pressure, and oxygen-free conditions, causing chemical reactions or physical changes between the particles to form a dense bulk material. However, hot pressing has disadvantages such as high energy consumption, long production cycle, and low production efficiency.

[0004] Therefore, improving the production efficiency of thermoelectric materials is an urgent problem that needs to be solved. Summary of the Invention

[0005] The main objective of this application is to provide a p-type bismuth telluride-based thermoelectric material and its mass production method, aiming to solve the technical problem of how to improve the production efficiency of thermoelectric materials.

[0006] To achieve the above objectives, this application provides a p-type bismuth telluride-based thermoelectric material, wherein the p-type bismuth telluride-based thermoelectric material has the following general chemical formula:

[0007] Bi 2-x-y Zn y Sb x Te3; where 1.5≤x≤1.6, 0.01≤y≤0.05.

[0008] Furthermore, in one embodiment, x is 1.55 and y is 0.03.

[0009] Furthermore, to achieve the above objectives, this application also provides a method for the mass production of p-type bismuth telluride-based thermoelectric materials, comprising the following steps:

[0010] Step 1: Weigh Bi, Zn, Sb, and Te according to the stoichiometry of p-type bismuth telluride-based thermoelectric materials.

[0011] Step 2: Place the weighed material into a quartz tube for melting to obtain a melted material ingot;

[0012] Step 3: The smelted material ingots are ball-milled using a ball mill.

[0013] Step four: Place the ball-milled powder into a graphite mold and perform discharge plasma sintering to obtain p-type bismuth telluride-based thermoelectric material.

[0014] Furthermore, in one embodiment, during step two, the melting process involves first heating to 650°C and holding at that temperature, then heating to 800°C and holding at that temperature, and finally cooling down.

[0015] Furthermore, in one embodiment, the duration of the first heating is 2.5h to 3.5h, the duration of the second heating is 0.5h to 1.5h, the duration of the cooling is 3.5h to 4.5h, the duration of the first heat preservation is 1.5h to 2.5h, and the duration of the second heat preservation is 9.5h to 10.5h.

[0016] Furthermore, in one embodiment, in step three, the ball milling speed is 800 r / min to 1000 r / min, and the ball milling time is 20 min to 30 min.

[0017] Furthermore, in one embodiment, during step four, when performing discharge plasma sintering, the temperature is first raised to 450°C, then raised to 500°C and held at that temperature, and finally cooled down.

[0018] Furthermore, in one embodiment, the diameter of the graphite mold is 30-100 mm, and the pressure corresponding to the discharge plasma sintering is 30 MPa to 40 MPa.

[0019] Furthermore, in one embodiment, the duration of the first heating is 8 min to 12 min, the duration of the second heating is 2 min to 4 min, and the duration of the heat preservation is 10 min to 15 min.

[0020] Furthermore, in one embodiment, in step one, according to the chemical formula Bi 2-x-y Zn y Sb x To determine the stoichiometry of Te3, Bi, Zn, Sb, and Te were weighed separately, and the weight of the material after weighing was 100g-1000g.

[0021] This application involves weighing Bi, Zn, Sb, and Te according to the stoichiometric ratio of p-type bismuth telluride-based thermoelectric materials; then melting the weighed materials in a quartz tube to obtain a molten ingot; subsequently, ball milling the molten ingot; and finally, placing the ball-milled powder into a graphite mold and performing discharge plasma sintering to obtain p-type bismuth telluride-based thermoelectric materials. Using discharge plasma (SPS) technology for sintering allows for the rapid production of dense thermoelectric materials, saving time and costs. The thermoelectric performance of the sintered product is comparable to that of hot pressing sintering, and the weight of a single finished product can reach up to 1000g, thereby effectively improving production efficiency and saving energy. Attached Figure Description

[0022] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with this application and, together with the description, serve to explain the principles of this application.

[0023] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, for those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0024] Figure 1 A schematic flowchart of Example 1 of the method for mass production of p-type bismuth telluride-based thermoelectric materials in this application;

[0025] Figure 2 The results show the test results of the thermoelectric performance of the p-type bismuth telluride-based thermoelectric material of this application.

[0026] The realization of the purpose, functional features and advantages of this application will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0027] It should be understood that the specific embodiments described herein are merely illustrative of this application and are not intended to limit this application.

[0028] To better understand the technical solution of this application, a detailed description will be provided below in conjunction with the accompanying drawings and specific implementation methods.

[0029] The main solution of this application is as follows: Step 1, weigh Bi, Zn, Sb and Te respectively according to the stoichiometric ratio of p-type bismuth telluride-based thermoelectric material; Step 2, put the weighed materials into a quartz tube for melting to obtain a melted material ingot; Step 3, ball mill the melted material ingot; Step 4, put the ball-milled powder into a graphite mold and perform discharge plasma sintering to obtain p-type bismuth telluride-based thermoelectric material.

[0030] Currently, thermoelectric materials are a class of functional materials that achieve direct coupling and conversion of thermal and electrical energy through the Seebeck and Peltier effects of semiconductor materials. Due to their advantages such as being pollution-free, noise-free, small in size, long in life, and highly reliable, they are widely used in waste heat power generation, aerospace, military equipment, and household appliances. Currently, commercially available p-type Bi... 2-x Sb x Te3 thermoelectric materials are primarily produced using hot pressing (HP) technology. This technology processes powdered or granular materials under high temperature, high pressure, and an oxygen-free environment, causing chemical reactions or physical changes between the particles to form a dense bulk material. However, hot pressing has drawbacks such as high energy consumption, long production cycles, and low production efficiency. Therefore, improving the production efficiency of thermoelectric materials is a pressing issue that needs to be addressed.

[0031] This application uses spark plasma (SPS) technology for sintering. Because spark plasma sintering has a short sintering time, a fast heating rate, and an easy-to-control sintering process, it can sinter dense thermoelectric materials in a short time, saving time and costs. The thermoelectric properties of the sintered finished product are comparable to those of hot pressing sintering, and the weight of a single finished product can be as high as 1000g, thereby effectively improving production efficiency and saving energy.

[0032] One embodiment of this application discloses a p-type bismuth telluride-based thermoelectric material, which has the following general chemical formula: Bi 2-x-y Zn y Sb x Te3; where 1.5≤x≤1.6, 0.01≤y≤0.05.

[0033] Furthermore, x takes the value of 1.55, and y takes the value of 0.03, meaning the chemical formula of the p-type bismuth telluride-based thermoelectric material is Bi. 0.42 Zn 0.03 Sb 1.55 Te3.

[0034] Furthermore, this application proposes a method for the mass production of p-type bismuth telluride-based thermoelectric materials according to the first embodiment. Please refer to [link / reference needed]. Figure 1 The method for mass production of the p-type bismuth telluride-based thermoelectric material includes:

[0035] Step 1: Weigh Bi, Zn, Sb, and Te according to the stoichiometry of p-type bismuth telluride-based thermoelectric materials.

[0036] In this embodiment, Bi, Zn, Sb, and Te are first weighed according to the stoichiometric ratio of p-type bismuth telluride-based thermoelectric materials to obtain the weighed materials. Preferably, the materials can be weighed according to the chemical formula Bi. 2-x-y Zn y Sb xThe stoichiometric ratio of Te3 is determined by weighing Bi, Zn, Sb, and Te separately to obtain a weighed material with a weight of 100g-1000g, preferably 1000g. Specifically, the material can be weighed according to the chemical formula Bi. 0.42 Zn 0.03 Sb 1.55 Bi, Zn, Sb and Te were weighed in stoichiometric proportions for Te3.

[0037] Bi, Zn, Sb, and Te can all be in powder or granule form.

[0038] Step 2: Place the weighed material into a quartz tube for melting to obtain a melted material ingot;

[0039] In this embodiment, the weighed material is first placed into a quartz tube, and the weighed material in the quartz tube is then melted to obtain a melted material ingot.

[0040] Specifically, during the smelting process, the temperature is first raised to 650°C and held, then raised to 800°C and held, and finally lowered to room temperature (e.g., 30°C) to obtain the smelted material ingot.

[0041] Further, the duration of the first heating is 2.5h to 3.5h, the duration of the second heating is 0.5h to 1.5h, the duration of the cooling is 3.5h to 4.5h, the duration of the first holding is 1.5h to 2.5h, and the duration of the second holding is 9.5h to 10.5h. Preferably, the duration of the first heating is 3h, the duration of the second heating is 1h, the duration of the cooling is 4h, the duration of the first holding is 2h, and the duration of the second holding is 10h. That is, the melting process is as follows: heating from room temperature (e.g., 30°C) to 650°C over 3h, then holding at 650°C for 2h, then heating to 800°C over 1h, holding at 800°C for 10h, and finally cooling to room temperature (e.g., 30°C) over 4h.

[0042] Step 3: The smelted material ingots are ball-milled using a ball mill.

[0043] In this embodiment, after obtaining the smelted material ingot, the smelted material ingot is ball-milled to obtain ball-milled powder. The ball milling speed is 800 r / min to 1000 r / min, and the ball milling time is 20 min to 30 min. Preferably, the ball milling speed is 900 r / min, and the ball milling time is 25 min.

[0044] Step four: Place the ball-milled powder into a graphite mold and perform discharge plasma sintering to obtain p-type bismuth telluride-based thermoelectric material.

[0045] In this embodiment, after obtaining the ball-milled powder, the ball-milled powder is placed into a graphite mold. Specifically, the ball-milled powder can be sieved first to obtain sieved powder. The sieved powder is then placed into the graphite mold. During the process of placing the powder into the graphite mold, a certain amount of powder is added and compacted each time, and then a certain amount of powder is added and compacted again, until all 1 kg of material is placed into the graphite mold. The diameter of the graphite mold is 30-100 mm, preferably 80 mm.

[0046] In this embodiment, after the ball-milled powder is placed into a graphite mold, it is sintered using spark plasma sintering (SPS) technology to obtain a p-type bismuth telluride-based thermoelectric material. Specifically, during the spark plasma sintering process, the temperature is first raised to 450°C, then raised to 500°C and held at that temperature, and finally cooled down. The duration of the first heating is 8-12 minutes, the duration of the second heating is 2-4 minutes, the duration of the holding temperature is 10-15 minutes, and the pressure corresponding to the spark plasma sintering is 30-40 MPa. Preferably, the duration of the first heating is 10 minutes, the duration of the second heating is 3 minutes, the duration of the holding temperature is 12 minutes, and the pressure corresponding to the spark plasma sintering is 35 MPa. The specific sintering process can be as follows: heating from room temperature (e.g., 30°C) to 450°C over 10 minutes, then heating from 450°C to 500°C over 3 minutes, holding at 500°C for 10-15 minutes, and then cooling down to room temperature (e.g., 30°C).

[0047] Bi 0.42 Zn 0.03 Sb 1.55 Taking Te3 as an example, refer to Figure 2 , Figure 2 The results show the test results of the thermoelectric performance of the p-type bismuth telluride-based thermoelectric material of this application.

[0048] A 1 kg sample of p-type bismuth telluride-based thermoelectric material was cut and tested. The electrical and thermal properties of this kilogram-scale thermoelectric material were measured by cutting different regions, and its thermoelectric figure of merit zT was calculated. To characterize the uniformity of performance across different regions of the sintered product, the relative standard deviation (RSD) was introduced to represent the uniformity of performance parameters. A smaller RSD indicates lower dispersion and better uniformity. Generally, an RSD less than 10% is considered to indicate good uniformity. The calculation formula is as follows:

[0049] RSD = Standard deviation / Mean * 100%.

[0050] like Figure 2 As shown in Figure a, the conductivity in different regions is basically between 8.8 and 10.3 × 10⁻⁶. 4Near S / m, RSD is less than 6.5%.

[0051] like Figure 2 b represents Bi. 0.42 Zn 0.03 Sb 1.55 The curve of the Seebeck coefficient of Te3 alloy with temperature shows that the Seebeck coefficient of each region of the sample is relatively uniform. The Seebeck coefficient of the edge3 region is slightly higher than that of other regions, but the RSD is less than 2.4%.

[0052] like Figure 2 c shows Bi 0.42 Zn 0.03 Sb 1.55 The power factor curves of different regions of the Te3 sample as a function of temperature, with the power factor ranging from 3587.2 W / m². -1 K -2 and 3875.6Wm -1 K -2 Between these values, the RSD is less than 3.2%, and overall the power factor is relatively uniform.

[0053] like Figure 2 d is Bi 0.42 Zn 0.03 Sb 1.55 The graph shows the thermal conductivity of different regions of the Te3 alloy sample as a function of temperature. It can be seen that the thermal conductivity of the sample first decreases and then increases with increasing temperature. The total thermal conductivity of different regions of the sample does not fluctuate significantly, remaining generally between 1.06 W / m². -1 K -1 and 1.14Wm -1 K -1 Between these values, the RSD is less than 6.0%.

[0054] like Figure 2 As shown in e, κ is the sample's κ total -κ e The curve showing the relationship between temperature and RSD is less than 7.5%. Overall, the thermal performance is relatively uniform.

[0055] like Figure 2 f shows Bi 0.42 Zn 0.03 Sb 1.55 The thermoelectric figure of merit (zT) of Te3 alloy varies with temperature. The calculated power factor is relatively uniform across different regions, while maintaining low and uniform thermal conductivity. The final average zT for different regions is... ave The value is 1.1@300-425K, and the RSD is less than 5.0%.

[0056] The method for mass production of p-type bismuth telluride-based thermoelectric materials proposed in this embodiment involves weighing Bi, Zn, Sb, and Te according to the stoichiometric ratio of the p-type bismuth telluride-based thermoelectric material; then melting the weighed materials in a quartz tube to obtain a molten ingot; subsequently, ball milling the molten ingot; and finally, placing the ball-milled powder into a graphite mold and performing spark plasma sintering to obtain the p-type bismuth telluride-based thermoelectric material. Using spark plasma (SPS) technology for sintering allows for the rapid production of dense thermoelectric materials, saving time and costs. The thermoelectric performance of the sintered product is comparable to that of hot pressing sintering, and the weight of a single finished product can reach up to 1000g, thereby effectively improving production efficiency and saving energy.

[0057] The above are merely preferred embodiments of this application and do not limit the patent scope of this application. Any equivalent structural or procedural transformations made using the content of this application's specification and drawings, or direct or indirect applications in other related technical fields, are similarly included within the patent protection scope of this application.

Claims

1. A method for mass production of p-type bismuth telluride-based thermoelectric materials, characterized in that, Includes the following steps: Step 1: Weigh Bi, Zn, Sb, and Te according to the stoichiometric ratio of p-type bismuth telluride-based thermoelectric materials, where Bi is the chemical formula. 0.42 Zn 0.03 Sb 1.55 The stoichiometry of Te3 was determined by weighing Bi, Zn, Sb, and Te separately, and the weight of the material after weighing was 1000g. Step 2: Place the weighed material into a quartz tube for melting to obtain a melted material ingot; Step 3: The smelted material ingots are ball-milled using a ball mill. Step four: Place the ball-milled powder into a graphite mold and perform discharge plasma sintering to obtain p-type bismuth telluride-based thermoelectric material; In step two, during the melting process, the temperature is first raised to 650 ℃ and held, then raised to 800 ℃ and held, and finally cooled down. In step four, during the discharge plasma sintering, the temperature is first raised to 450 ℃, then raised to 500 ℃ and held, and finally cooled down. In step two, the duration of the first heating is 2.5 h to 3.5 h, the duration of the second heating is 0.5 h to 1.5 h, the duration of the cooling is 3.5 h to 4.5 h, the duration of the first heat preservation is 1.5 h to 2.5 h, and the duration of the second heat preservation is 9.5 h to 10.5 h.

2. The method for mass production of p-type bismuth telluride-based thermoelectric materials as described in claim 1, characterized in that, In step three, the ball milling speed is 800 r / min to 1000 r / min, and the ball milling time is 20 min to 30 min.

3. The method for mass production of p-type bismuth telluride-based thermoelectric materials as described in claim 1, characterized in that, The diameter of the graphite mold is 30-100 mm, and the pressure corresponding to the discharge plasma sintering is 30 MPa~40 MPa.

4. The method for mass production of p-type bismuth telluride-based thermoelectric materials as described in claim 1, characterized in that, In step four, the duration of the first heating is 8 min to 12 min, the duration of the second heating is 2 min to 4 min, and the duration of holding is 10 min to 15 min.

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