Preparation method of Bi2O3-doped Sb0. 7FeTe2 thermoelectric material
By combining Bi2O3 through high-temperature solid-state reaction and hot-pressing processes, the thermoelectric properties of FeTe2 were optimized, solving the problems of low Seebeck coefficient and electrical conductivity, thus improving thermoelectric performance and broadening its application scope.
Patent Information
- Application Number
- CN202510855664.4
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-06-25
- Publication Date
- 2025-11-14
AI Technical Summary
Existing FeTe2 functional materials have low Seebeck coefficients and electrical conductivity, low power factors, and unsatisfactory thermoelectric properties, resulting in a narrow range of applications and a lack of effective measures to optimize their electrical properties.
Sb0.7FeTe2 samples were prepared by high-temperature solid-state reaction method, and a certain amount of Bi2O3 was added by hot pressing process to optimize the thermoelectric properties of the pyrite-type compound FeTe2.
It increases the Seebeck coefficient and electrical conductivity of the material, improves the power factor, broadens the application scope, and enhances the thermoelectric conversion efficiency.
Smart Images
Figure CN120943637A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of thermoelectric materials technology, and more specifically, to a Bi₂O₃-doped Sb 0.7 Preparation method of FeTe2 thermoelectric material. Background Technology
[0002] Thermoelectric materials utilize the movement of charge carriers within their solid interiors to achieve the conversion between thermal energy and electrical energy. Thermoelectric power generation does not impose any pollution burden on the environment. Thermoelectric power generation technology can recover waste heat sources and convert them into the electrical energy we need in our daily lives. Thermoelectric devices produced by this method also have advantages such as long service life and easy control. The existing pyrite-type compound FeTe2 is a popular functional thermoelectric material in recent years. For example, the existing technology ("Rare Metal Materials and Engineering" by Qin Bingke et al., "Rare Metal Materials and Engineering") discloses a method for rapidly synthesizing single-phase alloy compound FeTe2 in the temperature range of 803.15–923.15 K using vacuum high-temperature sintering. The effect of different holding times on the prepared single-phase FeTe2 samples was investigated at a preparation temperature of 863.15 K. The prepared samples were analyzed by XRD and SEM, and the resistivity and Seebeck coefficient were measured at room temperature. The results show that... Within a temperature range of 803.15–923.15 K, a single-phase polycrystalline compound, FeTe2, can be rapidly prepared by high-temperature sintering. The prepared sample exhibits numerous micron-sized pores uniformly within its interior. Room-temperature electrical property testing revealed that the sample achieved a maximum Seebeck coefficient of 88.21 μV / K at a preparation temperature of 863.15 K and a holding time of 60 min. At a preparation temperature of 803.15 K and a holding time of 30 min, the sample achieved a minimum resistivity of 7.86 mΩ·cm. At a preparation temperature of 923.15 K and a holding time of 30 min, the sample achieved a maximum power factor of 53.82 μW / (m·K²) and a maximum ZT value of 0.0076.
[0003] It is evident that existing FeTe2 functional materials have the following drawbacks: low Seebeck coefficient and electrical conductivity, low power factor, and poor thermoelectric conversion efficiency, resulting in unsatisfactory thermoelectric performance and difficulty in widespread application. Furthermore, the lack of reasonable and effective optimization measures for the electrical properties of FeTe2 functional materials further limits their application scope. Secondly, Bi2O3 has a wide range of optical and electrical properties, such as excellent dielectric properties, photoconductivity and photoluminescence, and high refractive index. It is widely used in catalysts, optoelectronic materials, high-temperature superconducting materials, microelectronic components and other fields. In recent years, researchers have carried out research on Bi2O3 in the field of thermoelectric materials and as a second phase composite into other thermoelectric material systems. For example, the prepared SnTe composite with 2% Bi2O3 synergistically optimized thermoelectric performance through energy filtering effect, achieving a maximum ZT value of 0.9 at 823 K; the prepared WO3 ceramic with added Bi2O3 had conductivity and power factor that were 1-2 orders of magnitude higher than pure WO3; the prepared Ca3Co4O9 ceramic with composite Bi2O3 showed that the Seebeck coefficient increased from the initial 110 μV / K to 190 μV / K with increasing Bi2O3 content, but due to the relatively high resistivity of the material itself, the maximum ZT value of the sample with 6 wt% Bi2O3 at 1073 K was 0.25. It can be seen that the existing technology has not yet produced research on the composite of Bi2O3 into the FeTe2 thermoelectric material system.
[0004] In view of this, and to address the aforementioned problems, this invention aims to design a novel method for preparing thermoelectric materials, firstly by preparing Sb through a high-temperature solid-state reaction method. 0.7 The thermoelectric properties of FeTe2, a compound of pyrite type, were further optimized by combining a certain amount of Bi2O3 with the FeTe2 sample through a hot pressing process. Summary of the Invention
[0005] To solve the above technical problems, the present invention provides a Bi2O3-doped Sb 0.7 A method for preparing FeTe2 thermoelectric materials, including the preparation of Sb via a high-temperature solid-state reaction. 0.7 By combining FeTe2 samples with a certain amount of Bi2O3 through hot pressing, the thermoelectric properties of the ferrophosphate compound FeTe2 were optimized, increasing the Seebeck coefficient and electrical conductivity of the material, as well as the power factor, giving it excellent thermoelectric conversion efficiency and thus broadening its application scope, in order to solve the corresponding technical problems mentioned in the background art.
[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows: In a first aspect, the present invention relates to a Bi2O3-doped Sb 0.7 Preparation method of FeTe2 thermoelectric material Step 1: Preparation of Sb 0.7 FeTe2 metal powder; Step 2: The Sb prepared in Step 1... 0.7 FeTe2 metal powder is mixed with a certain amount of Bi2O3 powder and then cold-pressed to obtain a column. Step 3: Place the cylinder obtained in Step 2 into a graphite mold and prepare Sb using a hot pressing process. 0.7 FeTe2-x%Bi2O3 thermoelectric material.
[0007] Preferably, step one involves preparing Sb via a high-temperature solid-state reaction method. 0.7 The FeTe2 sample was synthesized at 873 K for 10 min, followed by grinding, cleaning, drying, and crushing to obtain Sb. 0.7 FeTe2 metal powder.
[0008] As a preferred option, x = 1, 3, 5, 7, 10, 15.
[0009] As a preferred value, x=15.
[0010] Preferably, the hot pressing process involves a synthesis temperature of 723–923 K, a holding time of 30 min, and a pressure of 1.5 MPa.
[0011] Preferably, the hot pressing process is performed at a synthesis temperature of 923K, a holding time of 30min, and a pressure of 1.5MPa.
[0012] Secondly, this invention relates to a thermoelectric material Sb 0.7 FeTe2-x%Bi2O3, using Bi2O3-doped Sb as described above 0.7 The FeTe2 thermoelectric material was prepared using a specific method.
[0013] Compared with the prior art, the beneficial effects of the present invention are: 1. In the technical solution of this invention, the introduction of Bi2O3 is beneficial to the crystallization of Sb2Te3. As the Bi2O3 content increases, the main peak of Sb2Te3 begins to shift to a lower angle. This is because Bi atoms occupy Sb vacancies or replace Sb atoms. Since Sb and Bi are in the same group, their atomic radii gradually increase, leading to lattice expansion. Therefore, the main peak of Sb2Te3 shifts to a lower angle. When the composite amount of Bi2O3 increases from 3% to 15%, the crystallinity of the sample improves significantly, with no obvious pores, indicating that the introduction of Bi2O3 is beneficial to the crystallization of the sample.
[0014] 2. In the technical solution of this invention, as the synthesis temperature of the hot-pressing process increases, the Seebeck coefficient of the obtained materials generally shows a continuous increasing trend, indicating that temperature is the main driving force at this point. At the same temperature, as the content of Bi2O3 increases, the Seebeck coefficient of all materials shows a gradual increasing trend. It is also clearly observed that the composite Bi2O3 sample is very sensitive to temperature; the higher the Bi2O3 content and the higher the temperature, the greater the increase in the Seebeck coefficient. Overall, the Seebeck coefficient of the material is greatly improved, increasing from a minimum of 82.72 μV / K to 171.38 μV / K, overcoming the shortcoming of the low Seebeck coefficient of intrinsic FeTe2, and providing experimental reference for subsequent research on FeTe2 thermoelectric materials.
[0015] The power factor of all materials increases with increasing temperature. Under the same hot-pressing synthesis temperature, when the synthesis temperature is below 823 K, the power factor of the samples does not show a clear trend. When the synthesis temperature is above 823 K, the power factor gradually shows a trend of increasing with increasing Bi2O3 content, indicating that the higher the temperature and the more doped the material, the better its electrical properties.
[0016] 3. The advantage of this invention is that Sb is first prepared by a high-temperature solid-state reaction method. 0.7 FeTe2 samples were then doped with Bi2O3 to induce Sb production. 0.7 Further modification of the FeTe2 system material increases the Seebeck coefficient and electrical conductivity of the thermoelectric material, increases the power factor, and enables it to have excellent thermoelectric conversion efficiency, thereby broadening its application scope. The improvement of electrical performance makes it suitable for production and research in multiple industries. By controlling the amount of Bi2O3 doping and the synthesis temperature of the hot-pressing process, the material's electrical properties are improved beyond those of existing technologies, achieving even better thermoelectric properties and thus obtaining a high-performance thermoelectric material, thereby enhancing its application value. Attached Figure Description
[0017] Figure 1 This is a graph showing the relationship between the density of samples prepared under different Bi2O3 contents and the Bi2O3 content in this invention (the synthesis temperature is 923K). Figure 2 The graph shows the relationship between the XRD patterns of samples prepared at different synthesis temperatures and the synthesis temperature in this invention (Bi2O3 content is 10%). Figure 3The figure shows the relationship between the XRD patterns of samples prepared under different Bi2O3 contents and the Bi2O3 content in this invention (the synthesis temperature is 923K); where Figure (a) is the XRD pattern under different Bi2O3 contents, and Figure (b) is a magnified sub-image of Figure (a). Figure 4 Figure 1 shows the SEM and EDS images of samples with different Bi2O3 contents in this invention (all synthesized at 923 K), where Figure 2(a) shows Sb 0.7 SEM images of FeTe2-3%Bi2O3 (50 μm scale bar), Figure (b) shows Sb 0.7 SEM images of FeTe2-15%Bi2O3 (50 μm scale bar), Figure (c) shows Sb 0.7 SEM images of FeTe2-15%Bi2O3 (10 μm scale bar), Figure (d) shows Sb 0.7 EDS plot of FeTe2-15%Bi2O3; Figure 5 Sb at different synthesis temperatures in this invention 0.7 Resistivity distribution of FeTe2-x%Bi2O3 sample; Figure 6 Sb at different synthesis temperatures in this invention 0.7 Seebeck coefficient distribution diagram of FeTe2-x%Bi2O3 sample; Figure 7 Sb at different synthesis temperatures in this invention 0.7 The power factor distribution of the FeTe2-x%Bi2O3 sample, with the subplot showing the relationship between the power factor and Bi2O3 content at a synthesis temperature of 923K. Figure 8 Sb at different test temperatures in this invention 0.7 Resistivity distribution diagram of FeTe2-x%Bi2O3 sample; Figure 9 Sb at different test temperatures in this invention 0.7 Seebeck coefficient distribution diagram of FeTe2-x%Bi2O3 sample; Figure 10 Sb at different test temperatures in this invention 0.7 Power factor distribution of FeTe2-x%Bi2O3 sample; Figure 11 Sb at different test temperatures in this invention 0.7 Thermal conductivity distribution of FeTe2-x%Bi2O3 samples; where Figure (a) is the total thermal conductivity, Figure (b) is the electronic thermal conductivity, and Figure (c) is the lattice thermal conductivity. Figure 12Sb at different test temperatures in this invention 0.7 ZT value distribution diagram of FeTe2-x%Bi2O3 sample; Detailed Implementation
[0018] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.
[0019] Unless otherwise specified, all raw materials used in the embodiments of the present invention are commercially available or obtainable by those skilled in the art; unless otherwise specified, all methods used in the embodiments of the present invention are methods mastered by those skilled in the art.
[0020] A Bi2O3-doped Sb 0.7 Preparation method of FeTe2 thermoelectric material, where x=1,3,5,7,10,15; Step 1: Preparation of Sb 0.7 FeTe2 metal powder; specifically, Sb is prepared via a high-temperature solid-state reaction method. 0.7 The FeTe2 sample was synthesized at 873 K for 10 min, followed by grinding, cleaning, drying, and crushing to obtain Sb. 0.7 FeTe2 metal powder; Step 2: The Sb prepared in Step 1... 0.7 FeTe2 metal powder is mixed with a certain amount of Bi2O3 powder and then cold-pressed to obtain a column. Step 3: Place the cylinder obtained in Step 2 into a graphite mold and prepare Sb using a hot pressing process. 0.7 FeTe2-x%Bi2O3 thermoelectric material, wherein the hot pressing process is a synthesis temperature of 723-923K, a holding time of 30min, and a pressure of 1.5MPa.
[0021] The thermoelectric material Sb 0.7 FeTe2-x%Bi2O3, using Bi2O3-doped Sb as described above 0.7 The FeTe2 thermoelectric material was prepared by a method for preparing thermoelectric materials, wherein the thermoelectric material Sb 0.7 FeTe2-x%Bi2O3 is a bulk material.
[0022] Examples 1-6: The preparation was carried out using the preparation process steps described above, except that the Bi2O3 content x and the synthesis temperature remained unchanged. The synthesis temperature in Example 1 is 723K, and the Bi2O3 content x=1; The synthesis temperature in Example 2 was 723K, and the Bi₂O₃ content was x=3; The synthesis temperature in Example 3 was 723K, and the Bi2O3 content was x=5; The synthesis temperature in Example 4 is 723K, and the Bi2O3 content is x=7; The synthesis temperature in Example 5 was 723K, and the Bi2O3 content was x=10; The synthesis temperature in Example 6 was 723K, and the Bi2O3 content was x=15; The synthesis temperature in Example 7 was 773 K, and the Bi₂O₃ content was x=1; The synthesis temperature in Example 8 is 773K, and the Bi2O3 content is x=3; The synthesis temperature in Example 9 is 773K, and the Bi2O3 content is x=5; The synthesis temperature in Example 10 was 773 K, and the Bi2O3 content was x=7; The synthesis temperature in Example 11 was 773K, and the Bi2O3 content was x=10; The synthesis temperature in Example 12 was 773 K, and the Bi2O3 content was x=15; The synthesis temperature in Example 13 was 823K, and the Bi2O3 content was x=1; The synthesis temperature in Example 14 was 823 K, and the Bi2O3 content was x=3; The synthesis temperature in Example 15 was 823K, and the Bi2O3 content was x=5; The synthesis temperature in Example 16 was 823K, and the Bi2O3 content was x=7; The synthesis temperature in Example 17 was 823K, and the Bi2O3 content was x=10; The synthesis temperature in Example 18 was 823K, and the Bi2O3 content was x=15; The synthesis temperature in Example 19 was 873 K, and the Bi2O3 content was x=1; The synthesis temperature in Example 20 is 873K, and the Bi2O3 content is x=3; The synthesis temperature in Example 21 is 873K, and the Bi2O3 content is x=5; The synthesis temperature in Example 22 is 873K, and the Bi2O3 content is x=7; The synthesis temperature in Example 23 was 873 K, and the Bi2O3 content was x=10; The synthesis temperature in Example 24 is 873K, and the Bi2O3 content is x=15; The synthesis temperature in Example 25 was 923 K, and the Bi2O3 content was x=1; The synthesis temperature in Example 26 was 923 K, and the Bi2O3 content was x=3; The synthesis temperature in Example 27 was 923K, and the Bi2O3 content was x=5; The synthesis temperature in Example 28 is 923K, and the Bi2O3 content is x=7; The synthesis temperature in Example 29 is 923K, and the Bi2O3 content is x=10; The synthesis temperature in Example 30 was 923 K, and the Bi2O3 content was x=15; The synthesis temperature in Example 31 is 973K, and the Bi2O3 content is x=10; Sample density analysis: Density analysis of the thermoelectric materials Sb obtained in Examples 25-30. 0.7 Density was measured using FeTe2-x%Bi2O3, such as Figure 1 As shown: like Figure 1 The figure shows the relationship between the density of samples prepared at different Bi₂O₃ contents and the Bi₂O₃ content (all synthesis temperatures were 923 K). It can be seen from the figure that the sample density continuously increases with the increase of Bi₂O₃ content, from an initial 6.78 g·cm⁻¹. -3 Increased to 7.28 g·cm³ -3 This indicates that 0–15% mol Bi₂O₃-Sb prepared under hot pressing... 0.7 FeTe2 thermoelectric materials are more dense and have an exceptionally smooth surface.
[0023] XRD data analysis of samples: Thermoelectric materials Sb obtained in Examples 5, 11, 17, 23, 29, and 31 0.7 FeTe2-x%Bi2O3 was subjected to X-ray diffraction analysis under diffraction angles of 20-80°, such as... Figure 2 As shown.
[0024] like Figure 2 The figure shows the XRD patterns of samples prepared at different synthesis temperatures as a function of synthesis temperature (Bi₂O₃ content is 10% in all samples). Figure 2As shown, the synthesis temperature ranges from 723 to 973 K. Experimental studies indicate that the volatilization of Te and the consumption of Te by Sb result in an excess of Fe. Since Fe has a lower electronegativity than Bi, when the hot-pressing sintering temperature is below 773 K, the excess Fe reacts with some Bi₂O₃ to form a certain amount of Fe₃O₄, leading to the precipitation of small amounts of Bi₂O₃ and Fe₃O₄. At synthesis temperatures of 823–923 K, the reaction between Fe and Bi₂O₃ is more complete, and the impurity peaks are predominantly Fe₃O₄. At a synthesis temperature of 973 K, the reaction is more complex, and the characteristic peaks of FeTe₂ are significantly enhanced while those of Sb₂Te₃ are weakened, indicating that the main phase structure of the hot-pressed, high-temperature sintered sample is still dominated by FeTe₂. At this temperature, due to the consumption of Fe, a trace amount of Bi₂O₃ precipitates. It is worth noting that the sample is fragile and difficult to shape at this temperature; therefore, 923 K was chosen as the highest possible synthesis temperature.
[0025] Thermoelectric materials Sb obtained in Examples 25-30 0.7 FeTe2-x%Bi2O3 was subjected to X-ray diffraction analysis under diffraction angles of 20-80°, such as... Figure 3 As shown.
[0026] Figure 3 The XRD patterns of samples prepared with different Bi2O3 contents are shown as a function of Bi2O3 content (the synthesis temperature was 923 K). Figure (a) shows the XRD patterns at different Bi2O3 contents. Figure (b) is a magnified sub-image of Figure (a), where the scanning angle is 27-30°; As shown in Figure (a), at higher temperatures, no obvious Bi2O3 characteristic peaks were observed with increasing Bi2O3 content, but the second phase Fe3O4 was consistently present in the sample, indicating that Fe and Bi2O3 reacted sufficiently. Furthermore, the characteristic peaks of Sb2Te3 remained almost unchanged while those of FeTe2 gradually weakened, suggesting that the introduction of Bi2O3 facilitated the crystallization of Sb2Te3. Figure (b) is a magnified sub-image of the Sb2Te3 characteristic peaks, scanned at angles of 27–30°. It can be observed that with increasing Bi2O3 content, the main peak of Sb2Te3 begins to shift to lower angles. This is because Bi atoms occupy Sb vacancies or replace Sb atoms. Since Sb and Bi are in the same group, their atomic radii gradually increase, leading to lattice expansion, thus causing the main peak of Sb2Te3 to shift to lower angles.
[0027] SEM and EDS analysis of samples: Thermoelectric materials Sb obtained in Examples 26 and 30 0.7FeTe2-x%Bi2O3 was analyzed using SEM and EDS images, such as... Figure 4 As shown.
[0028] in, Figure 4 The images show SEM and EDS images of samples with different Bi2O3 contents (all synthesized at 923 K), where Figure (a) shows Sb 0.7 SEM images (50 μm scale bar) of FeTe2-3%Bi2O3 (Example 2), Figure (b) shows Sb 0.7 SEM image (50 μm scale bar) of FeTe2-15%Bi2O3 (Example 6), Figure (c) shows Sb 0.7 SEM image (10 μm scale bar) of FeTe2-15%Bi2O3 (Example 6), Figure (d) shows Sb 0.7 EDS diagram of FeTe2-15%Bi2O3.
[0029] As can be seen from the figure, the crystallinity of the sample significantly improved from 3% to 15% Bi₂O₃ content, with no obvious pores, indicating that the introduction of Bi₂O₃ is beneficial to sample crystallization. The EDS elemental mapping in Figure (d) shows that O, Fe, Sb, Te, and Bi elements are uniformly distributed throughout the entire detection area of the sample. Notably, the energy dispersive spectroscopy (EDS) spectra of Sb and Bi are very similar, indicating enrichment of these two elements. Furthermore, the atomic percentage of each element in the sample can be observed from the EDS. For the Bi₂O₃ sample with the highest content of 15%, the atomic percentage of Bi is only 5.17%, approximately 21% of that of O. This indicates that most of the Bi element volatilizes due to its low melting point, resulting in no obvious Bi characteristic peaks precipitating in the XRD.
[0030] Room temperature electrical performance analysis: Thermoelectric materials Sb obtained in Examples 1-30 0.7 FeTe2-x%Bi2O3 was used for resistivity detection, Seebeck coefficient detection, and power factor detection, such as... Figure 5-7 As shown.
[0031] Figure 5 To synthesize Sb at different temperatures 0.7 Resistivity distribution of FeTe2-x%Bi2O3 samples; when the temperature is below 773K, Bi2O3 does not fully participate in the reaction due to insufficient initial kinetic energy. The introduction of Bi2O3 increases the carrier concentration, causing all samples to show increased Sb content. 0.7The resistivity of FeTe2-x%Bi2O3 (1≤x≤15) decreases sharply. As the temperature increases above 773K, the activity of Bi2O3 is activated, and it reacts fully with excess Fe, resulting in an unusually complex crystal structure and inconsistent resistivity trends. Specifically, when the Bi2O3 percentage is less than or equal to 5%, the resistivity initially decreases and then stabilizes with increasing sintering temperature. When the Bi2O3 percentage increases to 7%~15%, the resistivity initially increases and then decreases with increasing temperature. At a synthesis temperature of 873K, Sb... 0.7 The FeTe2-1%Bi2O3 bulk thermoelectric material has the lowest resistivity, with a minimum value of 0.81 mΩ·cm.
[0032] Figure 6 To synthesize Sb at different temperatures 0.7 Seebeck coefficient distribution of FeTe2-x%Bi2O3 samples: With increasing synthesis temperature, the Seebeck coefficient of sample x=1 initially increases and then stabilizes, while the Seebeck coefficients of the other samples show a continuous increasing trend, indicating that temperature is the main driving force at this point. At the same temperature, with increasing Bi2O3 content, the Seebeck coefficients of all samples gradually increase. It is also evident that the composite Bi2O3 samples are highly sensitive to temperature; the higher the Bi2O3 content and the higher the temperature, the greater the increase in the Seebeck coefficient. Overall, the Seebeck coefficient of the samples is significantly improved, increasing from a minimum of 82.72 μV / K to 171.38 μV / K, overcoming the low Seebeck coefficient of intrinsic FeTe2 and providing experimental reference for future research on FeTe2 thermoelectric materials.
[0033] Figure 7 To synthesize Sb at different temperatures 0.7 The power factor distribution of FeTe2-x%Bi2O3 samples is shown in the subplot, which illustrates the relationship between the power factor and Bi2O3 content at a synthesis temperature of 923 K. The figures show that the power factor of all bulk thermoelectric materials increases with increasing temperature. At the same temperature, when the synthesis temperature is below 823 K, the power factor of the samples does not exhibit a clear pattern. However, when the temperature is above 823 K, the power factor gradually increases with increasing Bi2O3 content, indicating that samples with higher Bi2O3 content and higher temperature exhibit better electrical properties. As shown in the subplot, at a higher temperature of 923 K, the Sb content of the sample... 0.7 The power factor of FeTe2-x%Bi2O3 (x=1,3,5,7,10,15) increased from the initial 914.49 μW / (m·K) 2The monotonically increased value reached 1847.26 μW / (m·K). 2 (), which increased by nearly 100%.
[0034] Variable-temperature thermoelectric performance analysis: Based on the optimal power factor at room temperature, a set of Sb samples were selected at a synthesis temperature of 923K. 0.7 The FeTe2-x%Bi2O3 (x=1,3,5,7,10,15) samples were subjected to variable temperature testing at temperatures ranging from 323 to 673 K. Specifically, the thermoelectric materials Sb obtained in Examples 25-30 were tested. 0.7 The electrical properties of FeTe2-x%Bi2O3 were analyzed at temperatures ranging from 323 to 673 K, including resistivity, Seebeck coefficient, power factor, thermal conductivity, and ZT value. Figure 8-12 As shown.
[0035] Figure 8 To test Sb at different test temperatures 0.7 Resistivity distribution diagram of FeTe2-x%Bi2O3 sample; from Figure 8 As can be seen from the data, as the test temperature increases, Sb 0.7 The resistivity of the FeTe2-x%Bi2O3 (1≤x≤3) sample increased, while the resistivity of the other samples showed a trend of first increasing and then decreasing. At the test temperature of 323K, the resistivity of the Sb sample... 0.7 The resistivity of FeTe2-1%Bi2O3 reached a minimum of 0.59 mΩ·cm, which is lower than that of Sb synthesized by solid-state reaction method. 0.7 The decrease in FeTe2 content indicates that a low Bi2O3 content is beneficial for reducing resistivity. However, when the Bi2O3 content increases, the resistivity increases again.
[0036] Figure 9 To test Sb at different test temperatures 0.7 Seebeck coefficient distribution of FeTe2-x%Bi2O3 samples; from Figure 9 The curves showing the Seebeck coefficient of the samples changing with the test temperature reveal that, overall, the Seebeck coefficient of all samples decreases with increasing test temperature. When x > 5, within the range of 323–523 K, the Seebeck coefficient of all samples is greater than 100 μV / K, significantly superior to that of Sb synthesized by high-temperature solid-state reaction. 0.7 FeTe2 sample. Sb in the sample was measured at 323 K. 0.7 The FeTe2-15%Bi2O3 yielded a maximum Seebeck coefficient of 155.32 μV / K, which was slightly lower than the Seebeck coefficient at room temperature.
[0037] Figure 10 To test Sb at different test temperatures 0.7 Power factor distribution of FeTe2-x%Bi2O3 sample; from Figure 10 It can be seen from the sample Sb 0.7 The power factor of FeTe2-x%Bi2O3 (x=1,3,5,7,10,15) showed a decreasing trend with increasing test temperature. Although the resistivity and Seebeck coefficient of all samples decreased relative to room temperature, the maximum power factor of all samples at 323K exceeded 1200 μW / (m·K). 2 The above demonstrates that even trace amounts of Bi₂O₃ can optimize its electrical properties. At 323 K, the sample Sb... 0.7 The FeTe2-15%Bi2O3 solution achieved a maximum power factor of 1786.99 μW / (m·K). 2 The value at this time is related to the sample Sb. 0.7 1769.56 μW / (m·K) of FeTe2-10%Bi2O3 2 The values are very close, and from Figure 10 The overall electrical properties of Sb can be seen from this. 0.7 FeTe2-10%Bi2O3 compared to Sb 0.7 FeTe2-15%Bi2O3 is even better.
[0038] Figure 11 To test Sb at different test temperatures 0.7 Thermal conductivity distribution of FeTe2-x%Bi2O3 samples; Figure (a) shows the total thermal conductivity, Figure (b) shows the electronic thermal conductivity, and Figure (c) shows the lattice thermal conductivity. From the figures, it can be seen that with increasing test temperature, the total thermal conductivity of the samples first decreases and then increases, while the electronic thermal conductivity gradually increases. The lattice thermal conductivity tends to decrease continuously at x=1, while the other samples tend to decrease first and then increase. Figures (b) and (c) show that with increasing test temperature, at low Bi2O3 content, the thermal conductivity is mainly contributed by electronic thermal conductivity. With increasing Bi2O3 content, the thermal conductivity mainly comes from lattice thermal conductivity. Overall, the composite Bi2O3 increases both the electronic and lattice thermal conductivity of the samples, therefore the Sb... 0.7 The total thermal conductivity of FeTe2-x%Bi2O3 (x=1,3,5,7,10,15) relative to that of sample Sb 0.7 For FeTe2, the increase is somewhat observed. When the test temperature is 373K, Sb... 0.7 The lowest thermal conductivity was obtained for the FeTe2-15%Bi2O3 sample, which was 1.85 W / (m·K).
[0039] Figure 12 To test Sb at different test temperatures 0.7 The ZT value distribution of FeTe2-x%Bi2O3 samples shows that the ZT values of all samples first increase and then decrease with increasing test temperature. The composite Bi2O3 significantly increases the Seebeck coefficient to some extent, but the increase in thermal conductivity and resistivity is also limited due to the increase in thermal conductivity and resistivity caused by the introduction of Bi2O3. At a test temperature of 323 K, the ZT value of sample Sb... 0.7 FeTe2-15%Bi2O3 achieved a maximum ZT value of 0.31, which is similar to that of the sample Sb. 0.7 The ZT value of FeTe2 was increased by approximately 24% compared to 0.25.
[0040] Experimental results show that Sb was prepared by a high-temperature solid-state reaction method. 0.7 FeTe2 samples were combined with a certain amount of Bi2O3 via hot pressing to further optimize the thermoelectric properties of the pyrite-type compound FeTe2. With increasing Bi2O3 content, the Seebeck coefficient of the samples showed a significant increasing trend. The Sb sample synthesized by the high-temperature solid-state reaction method... 0.7 The resistivity of FeTe2 increased from 85.39 μV / K to 171.38 μV / K after hot-pressing and sintering with 15% Bi2O3 composite, nearly doubling. However, with the increase in Bi2O3 composite content, the resistivity and thermal conductivity of the sample also increased. Finally, at a test temperature of 323 K, the resistivity and thermal conductivity of the Sb sample... 0.7 FeTe2-15%Bi2O3 achieved a maximum ZT value of 0.31, compared to 1.57 × 10⁻⁶ for pure FeTe2. −2 It has increased by nearly 20 times, representing a significant improvement.
[0041] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.
Claims
1. A Bi₂O₃-doped Sb 0.7 The method for preparing FeTe2 thermoelectric materials is characterized by... Step 1: Preparation of Sb 0.7 FeTe2 metal powder; Step 2: The Sb prepared in Step 1... 0.7 FeTe2 metal powder is mixed with a certain amount of Bi2O3 powder and then cold-pressed to obtain a column. Step 3: Place the cylinder obtained in Step 2 into a graphite mold and prepare Sb using a hot pressing process. 0.7 FeTe2-x%Bi2O3 thermoelectric material.
2. A Bi₂O₃-doped Sb according to claim 1 0.7 The method for preparing FeTe2 thermoelectric materials is characterized by... Step one specifically involves preparing Sb via a high-temperature solid-state reaction method. 0.7 The FeTe2 sample was synthesized at 873 K for 10 min, followed by grinding, cleaning, drying, and crushing to obtain Sb. 0.7 FeTe2 metal powder.
3. A Bi₂O₃-doped Sb according to claim 2 0.7 The method for preparing FeTe2 thermoelectric materials is characterized by... x=1,3,5,7,10,15。 4. A Bi₂O₃-doped Sb according to claim 3 0.7 The method for preparing FeTe2 thermoelectric materials is characterized by... x=15。 5. A Bi₂O₃-doped Sb according to claim 3 0.7 The method for preparing FeTe2 thermoelectric materials is characterized by... The hot pressing process involves a synthesis temperature of 723–923 K, a holding time of 30 min, and a pressure of 1.5 MPa.
6. A Bi₂O₃-doped Sb according to claim 5 0.7 The method for preparing FeTe2 thermoelectric materials is characterized by... The hot pressing process involves a synthesis temperature of 923K, a holding time of 30min, and a pressure of 1.5MPa.
7. A thermoelectric material Sb 0.7 FeTe2-x%Bi2O3, characterized in that, Using Bi2O3 doped Sb as described in any one of claims 1-6 0.7 The FeTe2 thermoelectric material was prepared using a specific method.