Bi1-xSbx single crystal material, thermoelectric refrigeration device and preparation method and application of thermoelectric refrigeration device

Abstract

The invention relates to a Bi (1-x) Sbx single crystal material, a thermoelectric refrigeration device and a preparation method and application of the thermoelectric refrigeration device. The Bi < 1-x > Sb < x > single crystal material is prepared through a zone melting technology and is uniform in component and consistent in orientation; wherein in the Bi < 1-x > Sb < x > single crystal material, the value range of x is 0.1 to 0.15. Then, the Bi < 1-x > Sbx single-crystal thermoelectric leg with the Ni electrode layer and the BiSbTe thermoelectric leg which are obtained through the subsequent steps are welded to the aluminum nitride ceramic plate with the Cu coating layer through Bi < 0.58 > Sn < 0.42 > welding flux, and the Bi < 1-x > Sbx-based single-stage thermoelectric refrigeration device is further obtained; the refrigerating capacity of the refrigerating device can be further improved through solder in a cascade assembly mode, the lowest refrigerating temperature of the six-stage refrigerating device prepared through the method can reach 130 K, the six-stage refrigerating device is suitable for cooling application of the high-temperature superconductor, conversion of the YBa2Cu3O7 high-temperature superconductor from a normal state to a superconducting state is successfully achieved, and the application range of the YBa2Cu3O7 high-temperature superconductor is widened. The wide application prospect in the low-temperature field is shown.

Description

Technical Field

[0001] The present invention relates to the technical field of thermoelectric refrigeration, and in particular to a Bi 1-x Sb x Single crystal materials, thermoelectric refrigeration devices, and their preparation methods and applications. Background Art

[0002] Creating a stable cryogenic environment is crucial for superconducting applications, which place extremely high demands on temperature stability and low-vibration environments. Even small temperature fluctuations or mechanical vibrations can seriously affect the performance and accuracy of the system. Superconductors can only exhibit their unique physical properties below their critical transition temperature, which has now been raised to 130K at normal pressure and even to 160K under high pressure conditions. However, traditional cryogenic refrigeration technologies, such as pulse tube coolers and Gifford-McMahon (GM) coolers, inevitably generate vibrations during operation due to their complex mechanical structures.

[0003] These vibrations can have adverse effects in precision applications of superconductors. For example, in nuclear magnetic resonance (NMR) equipment, vibrations can cause signal distortion, which in turn affects image quality and the accuracy of analysis. Therefore, researchers are actively seeking cryogenic cooling technologies that do not require mechanical parts to reduce vibrations and improve system stability and reliability.

[0004] As a solid-state solution, thermoelectric cooling technology uses carriers inside solids as the working medium. Since there are no moving parts, it can achieve vibration-free cooling. This makes it excel in vibration-sensitive applications such as precision instruments and quantum computing devices. In addition, thermoelectric coolers have the advantage of being maintenance-free, and have shown broad application prospects in environments such as deep sea or space where regular maintenance is difficult.

[0005] However, thermoelectric cooling faces dual challenges at the material and device levels in cryogenic applications. As the temperature decreases, the thermoelectric performance of the material decreases sharply, limiting its potential for application in deep cryogenic environments.

[0006] Existing thermoelectric refrigeration devices are mainly based on bismuth telluride-based (Bi2Te3) materials, which have excellent refrigeration performance in the room temperature range. However, the figure of merit (zT) of its thermoelectric performance deteriorates sharply at low temperatures and cannot meet the refrigeration requirements in the deep low temperature field (<170K). Multi-stage refrigerators provide a solution to achieve lower temperatures at the device level. In theory, a refrigeration temperature close to 0K can be achieved through infinite cascading. However, current commercial multi-stage refrigerators can only reach a minimum refrigeration temperature of 170K under the condition that the hot end is at room temperature, which is far from sufficient to meet the refrigeration requirements of high-temperature superconductors. Therefore, due to the limitations of thermoelectric materials and device design in the prior art, lower refrigeration temperatures cannot be provided.

[0007] Chinese patent document CN 118234360 A discloses an n-type lead selenide thermoelectric material, a thermoelectric refrigeration device and a preparation method thereof. The chemical formula of the n-type lead selenide thermoelectric material is Pb 1-x (GaSb) x Se 1-y , where 0 < x < 0.002 and 0 < y ≤ 0.007. The thermoelectric refrigeration device made of n-type Pb 0.99875 (GaSb) 0.00125 Se 0.999 material and p-type bismuth telluride material as the n-type and p-type thermoelectric legs respectively, and welding the n-type and p-type thermoelectric legs in series electrically and in parallel thermally on a copper-clad ceramic substrate with Pb95 / Sn5 solder achieves maximum refrigeration temperature differences of 38K, 46K, and 56K respectively when the hot end temperatures are 300K, 323K, and 343K. However, the temperature range for optimizing the performance of this thermoelectric material mainly focuses on near room temperature and above, and the thermoelectric refrigeration device is also for near room temperature and medium to high temperature applications, without taking into account refrigeration applications below room temperature and in lower temperature regions. Summary of the Invention

[0008] The purpose of the present invention is to provide a Bi 1-x Sb x single crystal material, a thermoelectric refrigeration device and its preparation method and application, and the prepared thermoelectric refrigeration device can provide a lower refrigeration temperature to meet the refrigeration requirements of high-temperature superconductors.

[0009] The purpose of the present invention can be achieved through the following technical solutions:

[0010] On the one hand, the present invention provides a Bi 1-x Sb x single crystal material, and the Bi 1-x Sb x single crystal material is prepared by zone melting technology, where,

[0011] the Bi 1-x Sbx In single crystal materials, the value of x ranges from 0.1 to 0.15;

[0012] The Bi 1-x Sb x The single crystal material has uniform composition and consistent orientation. 1-x Sb x The single crystal size of the single crystal material is 1cm 3 ~8cm 3 ;

[0013] The Bi 1-x Sb x The single crystal material is an n-type thermoelectric material.

[0014] In a second aspect, the present invention also provides a Bi 1-x Sb x A method for preparing a single crystal material comprises the following steps:

[0015] S1. According to Bi 1-x Sb x The stoichiometric ratio of each element in the single crystal material is used to weigh Bi fragments and Sb fragments as raw material fragments;

[0016] S2, the raw material fragments are uniformly mixed and calcined under sealed vacuum conditions until they reach a molten state, and then water quenched to prepare Bi 1-x Sb x Multicrystalline ingot;

[0017] S3. Bi 1-x Sb x The polycrystalline ingot is cut into pieces and placed in a quartz tube with the tip at a 90° angle, which is then vacuum-sealed;

[0018] S4, the Bi-containing 1-x Sb x The tip of the quartz tube of the polycrystalline ingot is placed in the center of the heating zone in the zone melting furnace. Bi is obtained by zone melting. 1-x Sb x Single crystal;

[0019] S5, along the Bi obtained in step S3 1-x Sb x The crystal growth direction of the single crystal is tapped to obtain Bi along the cleavage plane direction. 1-x Sb x Single crystal material.

[0020] Preferably, in step S1, the purity of the Bi fragments and the Sb fragments is greater than 99.999%.

[0021] Preferably, in step S2, the raw material fragments are evenly mixed and placed in a quartz tube, the quartz tube is evacuated and sealed, and the quartz tube is vertically hung in the center of the tube furnace.

[0022] Preferably, in step S2, the raw material fragments are kept at a temperature of 893-1093 K for 4-6 hours until they reach a molten state, and more preferably, they are kept at a temperature of 993 K for 5 hours until they reach a molten state.

[0023] Preferably, in step S3, Bi 1-x Sb x The polycrystalline ingot is cut into fragments, and the particle size of the fragments is 3 mm to 5 mm.

[0024] The vacuum sealing in step S3 of the present invention is to prevent the quartz tube from 1-x Sb x As the material slowly solidifies, it expands in volume, causing the quartz tube to crack.

[0025] Preferably, in step S4, the central temperature of the heating area is controlled to be 573K to 773K, and the quartz tube is slowly lowered at a speed of 0.8 to 1.5 μm / s until the Bi 1-x Sb x The top of the multicrystalline ingot is lowered below the molten zone and melted one or more times.

[0026] Preferably, in step S4, the size of the heating zone of the zone smelting furnace is 5-10 mm.

[0027] Preferably, in step S5, a sharp object is used to knock along the crystal growth direction, and the sharp object includes a metal needle tip or a knife.

[0028] In a third aspect, the present invention further provides a thermoelectric cooling device, comprising the Bi 1-x Sb x Single crystal material.

[0029] Preferably, the thermoelectric cooling device comprises Bi 1-x Sb x Single-stage thermoelectric cooling device or Bi 1-x Sb x Based on multi-stage thermoelectric cooling device, the Bi 1-x Sb x The multi-stage thermoelectric cooling device is composed of Bi 1-x Sb x The basic single-stage thermoelectric cooling device is obtained by cascading assembly through solder;

[0030] The Bi 1-x Sb x The single-stage thermoelectric cooling device includes Bi1-x Sb x Base single pair cooling module or Bi 1-x Sb x The Bi 1-x Sb x The refrigeration module is made of Bi 1-x Sb x The base pair of refrigeration modules is assembled by soldering.

[0031] In a fourth aspect, the present invention further provides a method for preparing the above-mentioned thermoelectric refrigeration device, comprising the following steps:

[0032] a. Change Bi 1-x Sb x Single crystal material and BiSbTe material cutting to obtain Bi 1-x Sb x Single crystal thermoelectric legs and BiSbTe thermoelectric legs;

[0033] b. Bi obtained in step a 1-x Sb x The single crystal thermoelectric legs and BiSbTe thermoelectric legs were sequentially washed with alkali, water, acid, and water to remove oil stains;

[0034] c. Remove the oil-stained Bi obtained in step c. 1-x Sb x The single crystal thermoelectric leg and the BiSbTe thermoelectric leg are electroplated separately to obtain Bi with Ni electrode layer. 1-x Sb x Single crystal thermoelectric legs and BiSbTe thermoelectric legs;

[0035] d. The Bi with Ni electrode layer obtained in step c 1-x Sb x The single crystal thermoelectric legs and BiSbTe thermoelectric legs are obtained by using Bi 0.58 Sn 0.42 The Bi 1-x Sb x Base single pair refrigeration module;

[0036] e. Bi obtained in step d 1-x Sb x The Bi-based refrigeration module is assembled and cascaded by soldering. 1-x Sb x Based on multi-stage thermoelectric cooling device.

[0037] Preferably, in step a, the BiSbTe material is a p-type thermoelectric material.

[0038] Further preferably, in step a, the BiSbTe material includes p-type Bi2Te3 thermoelectric material.

[0039] Preferably, in step a, the Bi 1-x Sb x The size of the single crystal thermoelectric leg is (0.4~0.8)*(1.0~1.6)*(5~15)mm 3 .

[0040] Preferably, in step a, the size of the BiSbTe thermoelectric leg is (1.0-1.5)*(1.0-1.5)*(5-15) mm 3 .

[0041] Preferably, in step a, the cutting is performed using diamond wire.

[0042] Preferably, in step b, the alkali washing refers to cleaning and removing oil stains in an alkaline solution containing 60-80 g / L NaOH, 20-40 g / L Na2CO3, 10-20 g / L Na3PO4·12H2O and 4-8 g / L Na2SiO3.

[0043] Further preferably, in step b, the alkaline washing refers to washing and removing oil stains in an alkaline solution containing 70 g / L NaOH, 30 g / L Na2CO3, 15 g / L Na3PO4·12H2O and 6 g / L Na2SiO3.

[0044] Preferably, in step b, the pickling refers to heavy washing with hydrochloric acid at a concentration of 36wt% to 38wt% to remove residual alkali solution.

[0045] Preferably, in step c, the electroplating treatment refers to a process comprising 200-280 g / L NiSO4·7H2O, 30-40 g / L H3BO3, 5-15 g / L NaCl, 60-80 g / L Na2SO4, 60-80 g / L MgSO4 and 0.9-1.0 g / L C 12 H 25 SO4Na plating solution at 35-55°C, 1-2.4A / cm 2 The current density is electroplated for 6 to 15 minutes.

[0046] Further preferably, in step c, the electroplating treatment refers to a process containing 240 g / L NiSO4·7H2O, 35 g / L H3BO3, 10 g / L NaCl, 70 g / L Na2SO4, 70 g / L MgSO4 and 0.985 g / L C 12 H 25 SO4Na plating solution at 45°C, 1.8A / cm2 The current density was electroplated for 10 min.

[0047] In the present invention, Ni (nickel) used in the electroplating process is used as the electrode material. The Ni electrode layer can effectively reduce the contact resistance, prevent element diffusion, and ensure good contact between the thermoelectric legs and the solder.

[0048] Preferably, in step d, the Bi having a Ni electrode layer 1-x Sb x Before welding the single crystal thermoelectric legs and the BiSbTe thermoelectric legs to the aluminum nitride ceramic plate with a Cu coating, the BiSbTe thermoelectric legs with a Ni electrode layer need to be welded to the aluminum nitride ceramic plate with a Cu coating. 1-x Sb x The side surfaces of the single crystal thermoelectric leg and the BiSbTe thermoelectric leg are polished to remove the Ni electrode layer plated on the side surfaces.

[0049] Preferably, in step d, the Bi 0.58 Sn 0.42 The melting point of the solder is 120°C to 145°C, more preferably 138°C.

[0050] Preferably, in step e, the melting point of the solder is 35-55°C, more preferably 45°C.

[0051] Further preferably, in step e, the solder is InSnBi alloy.

[0052] In a fifth aspect, the present invention further provides an application of the above-mentioned thermoelectric refrigeration device, wherein the thermoelectric refrigeration device is suitable for low-temperature refrigeration of high-temperature superconductors.

[0053] Preferably, the thermoelectric refrigeration device is applied to the cooling of the YBa2Cu3O7 superconductor to achieve stable operation in the superconducting state.

[0054] The present invention provides a Bi 1-x Sb x Single crystal materials, thermoelectric cooling devices, and their preparation methods and applications serve the cooling needs of high-temperature superconductors. At the material level, high-performance Bi-Sb alloys are used to replace traditional n-type Bi2Te3 materials, showing optimized cooling performance in low-temperature environments below 170K; at the device level, the geometric structure design of multi-stage cooling devices is optimized, the cascade efficiency is improved, and the cooling temperature as low as 130K is achieved. The present invention further applies the cooling device to the cooling of YBa2Cu3O7 high-temperature superconductors, demonstrating the application potential of thermoelectric cooling devices in the field of high-temperature superconductors.

[0055] The present invention prepares a Bi-Sb-based high-performance low-temperature refrigeration material that can be reliably used in low-temperature refrigeration. 1-x Sbx Single crystal materials have a high electrical power factor S 2 σ, where S is the Seebeck coefficient and σ is the electrical conductivity of the material. At the same time, the solid solution of Sb leads to a decrease in its lattice thermal conductivity, thereby comprehensively improving the thermoelectric performance of the material. Since the solute Sb has a large segregation coefficient in the matrix Bi, it is easy to cause the Sb composition to be inhomogeneous, resulting in poor repeatability of the thermoelectric performance. Compared with traditional smelting or sintering polycrystalline materials, single crystal Bi 1-x Sb x The thermoelectric performance of the material is more superior. Based on this, the present invention uses regional melting combined with control of its growth rate and temperature gradient to reduce the thermodynamic equilibrium driving force that promotes the diffusion of solute elements, and develops a method for preparing Bi with consistent orientation and uniform composition. 1-x Sb x Methods for single crystal materials.

[0056] The lowest refrigeration temperature of the commercial Bi2Te3-based multi-stage refrigeration device is only 170K. This invention aims to develop Bi2Te3-based multi-stage refrigeration devices for low-temperature applications. 1-x Sb x Based on the refrigeration device, it can replace Bi2Te3 material to further cool to a lower temperature. Preferably, the two-stage Bi-Sb based refrigeration device is connected with commercial Bi 2-x Sb x Te3-based cooling devices are cascaded to maximize cooling capacity over the entire temperature range.

[0057] Compared with the prior art, the present invention has the following beneficial effects:

[0058] (1) The present invention uses a zone melting technique to prepare intrinsic Bi with uniform composition and consistent orientation. 1-x Sb x Single crystal materials do not require other doping elements, thus avoiding the fluctuation of thermoelectric performance caused by uneven composition. 1-x Sb x Single crystal materials have significant advantages in anisotropy and exhibit more stable and reliable thermoelectric performance.

[0059] (2) The present invention adopts Bi 1-x Sb x The alloy replaces the traditional n-type Bi2Te3-based material. With its superior thermoelectric properties in the low-temperature zone, the thermoelectric refrigeration device prepared by this material shows better thermoelectric performance in a low-temperature environment below 170K, and the cooling temperature difference is about 1.7 times that of the commercial Bi2Te3-based device at the same temperature.

[0060] (3) Through multi-stage device geometry design, the present invention optimizes the device cascade efficiency, enabling the refrigeration device to achieve a refrigeration temperature as low as 130 K. This technological breakthrough overcomes the temperature limitation of traditional Bi2Te3-based refrigeration devices and significantly improves low-temperature refrigeration capabilities.

[0061] (4) The refrigeration device of the present invention is successfully applied to the low-temperature refrigeration of YBa2Cu3O7 high-temperature superconductor, demonstrating the great application potential of thermoelectric refrigeration technology in the field of high-temperature superconductivity and providing technical support for the further development of superconducting technology in the future. BRIEF DESCRIPTION OF THE DRAWINGS

[0062] Figure 1 is Bi in Example 1 0.85 Sb 0.15 Phase characterization and microscopic morphology of single crystal;

[0063] Figure 2 is Bi in Example 1 0.85 Sb 0.15 Electrical and thermal properties of single crystals at 80-300K and figure of merit of devices;

[0064] Figure 3 The Bi-containing 0.85 Sb 0.15 -Interface contact resistance and morphology of single-stage thermoelectric cooling devices based on single-pair cooling modules;

[0065] Figure 4 For the Bi-containing 0.85 Sb 0.15 - The device resistance and predicted internal resistance diagram of the single-stage thermoelectric cooling device of the single-pair cooling module and the three-pair cooling module measured by the AC method;

[0066] Figure 5 is a graph showing the change in cooling temperature difference over time of a single-stage thermoelectric cooling device containing a single pair of cooling modules at a hot end condition of 280-270K in Example 2;

[0067] Figure 6 Graph showing the cooling power and cooling efficiency of a single-stage thermoelectric cooling device containing a single pair of cooling modules in Example 2 under the hot end condition of 80-180K;

[0068] Figure 7 is a graph showing the change in cooling temperature difference over time of a single-stage thermoelectric cooling device containing three pairs of cooling modules at a hot end of 270K in Example 3;

[0069] Figure 8 Bi is YBa2Cu3O7 in Example 4 1-x Sb x The curve diagram of superconducting transition of the two-stage thermoelectric refrigeration device under refrigeration;

[0070] Fig. 9 This is a diagram of the minimum cooling temperature of the six-stage thermoelectric cooling device at different hot end temperatures in Example 5;

[0071] Fig.10 This is a structural diagram of the six-stage thermoelectric cooling device in Example 5. DETAILED DESCRIPTION

[0072] The present invention is described in detail below in conjunction with the accompanying drawings and specific embodiments. This embodiment is implemented based on the technical solution of the present invention, and provides a detailed implementation method and specific operation process, but the protection scope of the present invention is not limited to the following embodiments.

[0073] Unless otherwise specified, the reagents, methods, instruments and equipment used in the present invention are conventional reagents, methods, instruments and equipment in the art. Unless otherwise specified, the reagents and materials used in the following examples are commercially available.

[0074] Example 1

[0075] A kind of Bi 0.85 Sb 0.15 The specific preparation process of single crystal material is as follows:

[0076] (1) According to the stoichiometric ratio Bi 0.85 Sb 0.15 Weigh high-purity Bi and Sb fragments as raw materials.

[0077] (2) The raw material fragments are evenly mixed and placed in a quartz tube, which is then evacuated and sealed. The quartz tube is vertically hung in the center of a tube furnace. The quartz tube is kept at 993K for 5 hours to reach a molten state, and then quickly quenched with water to prepare Bi 0.85 Sb 0.15 Multicrystalline ingot.

[0078] (3) Take the polycrystalline ingot out of the quartz tube and cut it into pieces, place it in a quartz tube with the tip at a 90° angle, and evacuate and seal it again. This operation is to prevent the quartz tube from 0.85 Sb 0.15 As the material slowly solidifies, it expands in volume, causing the quartz tube to crack.

[0079] (4) The polycrystalline ingot in step (3) is placed in a zone melting furnace with a heating zone of 5-10 mm, the tip of the quartz tube is placed in the center of the heating zone, the temperature of the center of the heating zone is controlled to be 673 K, and the quartz tube is slowly lowered at a speed of 0.8 μm / s until the top of the ingot is lowered below the melting zone.

[0080] (5) Replace Bi in step (4) 0.85 Sb0.15 The single crystal is taken out of the quartz tube and struck with a sharp object along the crystal growth direction to obtain Bi 0.85 Sb 0.15 Single crystal material.

[0081] In this embodiment, the grown Bi 0.85 Sb 0.15 Single crystal ingots were cast, and single crystal samples were taken from three locations along the growth direction for phase and microstructural characterization. The results are as follows: Figure 1 . Phase characterization Figure 1 As shown in a-b, the c-axis lattice constant calculated from its XRD diffraction peak is highly consistent with the predicted value of Vegard's law, and the deviation between the three single crystal samples is less than 1%, which indicates that the grown single crystal has compositional uniformity. Figure 1 As shown in c, the scanning electron microscope (SEM) image further confirms that there is no Sb segregation in the crystal. 0.85 Sb 0.15 The compositional homogeneity of the crystal ensures the integration of subsequent refrigeration devices.

[0082] Figure 2 a~e are the low-temperature thermoelectric properties of samples from three different locations, showing excellent repeatability. In the temperature range of 100-200K, the Bi 0.85 Sb 0.15 The average zT value (thermoelectric figure of merit) of the single crystal is 0.37, which is better than that of commercial n-type Bi2Te3 materials. The thermal stability of its thermoelectric performance was evaluated through three thermal cycle tests, and the results showed that its thermoelectric performance was almost not degraded, demonstrating its excellent durability.

[0083] Example 2

[0084] A single-stage thermoelectric refrigeration device containing a single pair of refrigeration modules serving high-temperature superconductors, the specific implementation method of which is as follows:

[0085] (1) The Bi in the in-plane direction obtained in Example 1 was 0.85 Sb 0.15 The single crystal material and commercial BiSbTe material are cut to the required size using a diamond wire saw. The size of the p-type Bi2Te3 thermoelectric leg is 1.3*1.3*10mm 3 , n-type Bi 0.85 Sb 0.15 The size of the single crystal thermoelectric leg is 0.6*1.3*10mm 3 .

[0086] (2) The p-type Bi2Te3 thermoelectric legs and n-type Bi2Te3 thermoelectric legs obtained in step (1) are connected to the 0.85 Sb 0.15The single crystal thermoelectric legs were placed in an alkaline solution consisting of NaOH (70 g / L), Na2CO3 (30 g / L), Na3PO4·12H2O (15 g / L) and Na2SiO3 (6 g / L) to clean the oil residues from cutting.

[0087] (3) Rinse the two thermoelectric legs after alkaline washing with pure water, and then remove the residual alkaline washing solution in 36% to 38% hydrochloric acid.

[0088] (4) The two thermoelectric legs obtained in step (3) were rinsed with pure water and heated to 40 °C in a mixture of NiSO4·7H2O (240 g / L), H3BO3 (35 g / L), NaCl (10 g / L), Na2SO4 (70 g / L), MgSO4 (70 g / L) and C 12 H 25 SO4Na (0.985g / L) electroplating solution at 45℃, 1.8A / cm 2 The thermoelectric legs were electroplated to prepare weldable electrodes.

[0089] (5) Polishing the sides of the two thermoelectric legs with Ni electrode layers obtained in step (4) to remove the electrode layers plated on the sides, and obtaining the required sizes of p-type Bi2Te3 thermoelectric legs and n-type Bi 0.85 Sb 0.15 The two processed thermoelectric legs were assembled onto an aluminum nitride (AlN) ceramic plate with a Cu coating and a Bi with a melting point of 138°C was used. 0.58 Sn 0.42 The modules are assembled by soldering to obtain a single-stage thermoelectric cooling device containing a single pair of cooling modules.

[0090] The n-type Bi obtained in Example 1 0.85 Sb 0.15 After the in-plane single crystal and commercial p-type Bi2Te3 were combined into a single pair module, the device performance was investigated, such as Figure 2 As shown in Figure d, the device's thermoelectric figure of merit is significantly better than that of commercial Bi2Te3-based devices below 180K.

[0091] Figure 3 is the interface contact resistance and diffusion of the single pair of refrigeration modules. Figure 3 a, 3c show the average contact resistivity of the solder / Ni electrode layer / thermoelectric material interface: p-type Bi2Te3 is about 28μΩ·cm 2 , n-type Bi 0.85 Sb 0.15 In-plane single crystal 5.6μΩ·cm 2 . Further, if Figure 3As shown in b, 3d, scanning electron microscope (SEM) images show that the Ni electrode layer effectively prevents the element diffusion between the solder and the thermoelectric material. Figure 4 The total resistance of the single pair of cooling modules and the internal resistance predicted based on material properties show that the contact interface accounts for only about 5% of the total resistance of the device, thus ensuring minimal performance degradation.

[0092] The cooling performance of the single-stage thermoelectric cooling device containing a single pair of cooling modules developed in Example 2 in the range of 80 to 270 K is as follows: Figure 5 As shown. In the optimized current (I = I opt ) under the condition of maximum cooling temperature difference (ΔT max ), achieving about 85% of the predicted performance. When the hot end temperature is 179K, the ΔT max The ΔT of Bi2Te3 devices at the same temperature is about 21K, which is lower than the ΔT of 12K reported previously. max 80% higher. Figure 6 The figure shows the cooling power and cooling efficiency of the device under the hot end conditions of 80-180K. At 180K, it shows about 3.6kW / m 2 The low-temperature refrigeration power shows its potential for refrigeration at low temperatures.

[0093] Example 3

[0094] A single-stage thermoelectric refrigeration device containing three pairs of refrigeration modules serving high-temperature superconductors, the specific implementation method of which is as follows:

[0095] (1) The Bi in the in-plane direction obtained in Example 1 was 0.85 Sb 0.15 The single crystal material and commercial BiSbTe material are cut to the required size using a diamond wire saw. The size of the P-type Bi2Te3 thermoelectric leg is 1.5*1.5*7mm 3 , n-type Bi 0.85 Sb 0.15 The size of the single crystal thermoelectric leg is 0.7*1.3*7mm 3 .

[0096] (2) The two thermoelectric legs obtained in step (1) are placed in an alkaline solution composed of NaOH (70 g / L), Na2CO3 (30 g / L), Na3PO4·12H2O (15 g / L) and Na2SiO3 (6 g / L) to clean the oil stains remaining from cutting.

[0097] (3) Rinse the thermoelectric legs after alkaline washing with pure water, and then remove the residual alkaline washing solution in 36% to 38% hydrochloric acid.

[0098] (4) Rinse the thermoelectric legs obtained in step (3) with pure water and place them in a mixture of NiSO4·7H2O (240 g / L), H3BO3 (35 g / L), NaCl (10 g / L), Na2SO4 (70 g / L), MgSO4 (70 g / L) and C 12 H 25 SO4Na (0.985g / L) electroplating solution at 45℃, 1.8A / cm 2 The thermoelectric legs were electroplated to prepare weldable electrodes.

[0099] (5) Polishing the sides of the two thermoelectric legs with Ni electrode layers obtained in step (4) to remove the electrode layers plated on the sides, and obtaining the required sizes of p-type Bi2Te3 thermoelectric legs and n-type Bi 0.85 Sb 0.15 The two processed thermoelectric legs were assembled onto an aluminum nitride (AlN) ceramic plate with a Cu coating and a Bi with a melting point of 138°C was used. 0.58 Sn 0.42 The modules are assembled by soldering to obtain a single pair of refrigeration modules, and the three pairs of single pair of refrigeration modules are assembled by using an InSnBi alloy with a melting point of 45°C to obtain a single-stage thermoelectric refrigeration device containing three pairs of refrigeration modules.

[0100] Figure 7 The cooling performance of the single-stage thermoelectric cooling device containing three pairs of cooling modules in Example 3 when the hot end temperature is 270K has better repeatability than that of the single-stage thermoelectric cooling device containing a single pair of cooling modules, indicating that the method and the prepared device proposed in this example have reliability for repeated application.

[0101] Example 4

[0102] A multi-stage thermoelectric refrigeration device serving high temperature superconductivity, the specific implementation method of which is as follows:

[0103] The single-stage thermoelectric refrigeration device with a single pair of refrigeration modules and the single-stage thermoelectric refrigeration device with three pairs of refrigeration modules obtained in Examples 2 and 3 above were cascaded and assembled using an InSnBi alloy with a melting point of 45°C to obtain Bi 1-x Sb x Two-stage refrigeration device.

[0104] In this embodiment 4, a verification experiment was conducted to evaluate the feasibility of using a thermoelectric refrigeration device for high-temperature superconductor refrigeration. A YBa2Cu3O7 film with a superconducting transition temperature of about 91-91.4K was fixed on the cold end of the thermoelectric cooler, such as Figure 8As shown, the two-stage low-temperature thermoelectric refrigerator developed in the present invention successfully cooled the YBa2Cu3O7 film from 100K to 91K, thereby realizing its transition from a normal state to a superconducting state, confirming the potential possibility of applying the low-temperature thermoelectric device prepared in this embodiment to refrigeration in the superconducting field.

[0105] Example 5

[0106] For each operating temperature range, high-performance materials are selected to construct a multi-stage thermoelectric cooling device. The Bi prepared in Example 4 is 1-x Sb x The two-stage heat-customized cooling device based on Bi2Te3 is used as the low-temperature cooling device, and the commercial Bi2Te3-based four-stage refrigerator (2040 / 153 / 080MN / C02) of Ferrotec is used as the room-temperature cooling device to obtain a heterogeneous six-stage cooling device, whose structure is as follows: Fig.10 shown.

[0107] Fig. 9 It reflects the cooling temperature of the six-stage device. When each stage operates under its optimal current condition, the overall cooling performance is maximized. On this basis, the low-temperature thermoelectric cooler in this embodiment is designed by individual optimization of the working current of each stage. By optimizing the working conditions of the two-stage low-temperature cooler, this embodiment achieves a record-breaking minimum cooling temperature of about 130K under the condition of a hot end temperature of 300K. The cooling performance also shows stability after three heating and cooling thermal cycles.

[0108] In summary, the technical solution of the present invention has the following advantages:

[0109] 1. The present invention successfully prepared Bi with uniform composition and orientation by using zone melting technology 1-x Sb x Single crystal materials do not require doping, thus avoiding the resulting fluctuations in thermoelectric performance. Compared with conventional polycrystalline materials, this single crystal material exhibits more excellent anisotropy and provides more stable and reliable thermoelectric performance, which is crucial to ensuring the high efficiency and long-term stability of low-temperature refrigeration devices.

[0110] Second, the present invention uses Bi 1-x Sb x As a new type of n-type material, the alloy replaces the traditional n-type Bi2Te3 material. 1-x Sb x The excellent thermoelectric performance exhibited in the temperature range below 170K significantly enhances the cooling effect of the cooling device in low-temperature environments. The cooling temperature difference is about 1.7 times that of the Bi2Te3-based cooling devices on the market, thereby greatly improving the efficiency of low-temperature refrigeration.

[0111] 3. The present invention has also achieved a technical breakthrough, namely, successfully reducing the refrigeration temperature to a minimum of 130K. This achievement breaks the temperature limit of traditional Bi2Te3-based refrigeration devices and has been successfully applied to the refrigeration process of YBa2Cu3O7 high-temperature superconductors. This not only confirms the broad application prospects of thermoelectric refrigeration devices in the field of high-temperature superconducting technology, but also indicates that its application potential in this field has been further expanded.

[0112] The above description of the embodiments is to facilitate the understanding and use of the invention by those skilled in the art. It is obvious that those skilled in the art can easily make various modifications to these embodiments and apply the general principles described herein to other embodiments without creative work. Therefore, the present invention is not limited to the above embodiments, and improvements and modifications made by those skilled in the art based on the disclosure of the present invention without departing from the scope of the present invention should be within the scope of protection of the present invention.

Claims

1. A Bi 1-x Sb x Single crystal material, characterized in that The Bi 1-x Sb x The single crystal material is prepared by zone melting technology, in which: The Bi 1-x Sb x In single crystal materials, the value of x ranges from 0.1 to 0.15; The Bi 1-x Sb x The single crystal material has uniform composition and consistent orientation. 1-x Sb x The single crystal size of the single crystal material is 1cm 3 ~8cm 3 ; The Bi 1-x Sb x The single crystal material is an n-type thermoelectric material.

2. A Bi as claimed in claim 1 1-x Sb x A method for preparing a single crystal material, characterized in that: The following steps are involved: S1. According to Bi 1-x Sb x The stoichiometric ratio of each element in the single crystal material is used to weigh Bi fragments and Sb fragments as raw material fragments; S2, the raw material fragments are uniformly mixed and calcined under sealed vacuum conditions until they reach a molten state, and then water quenched to prepare Bi 1-x Sb x Multicrystalline ingot; S3. Bi 1-x Sb x The polycrystalline ingot is cut into pieces and placed in a quartz tube with the tip at a 90° angle, which is then vacuum-sealed; S4, the Bi-containing 1-x Sb x The tip of the quartz tube of the polycrystalline ingot is placed in the center of the heating zone in the zone melting furnace. Bi is obtained by zone melting. 1-x Sb x Single crystal; S5, along the Bi obtained in step S3 1-x Sb x The crystal growth direction of the single crystal is tapped to obtain Bi along the cleavage plane direction. 1-x Sb x Single crystal material.

3. A Bi according to claim 2 1-x Sb x A method for preparing a single crystal material, characterized in that: In step S2, the raw material fragments are evenly mixed and placed in a quartz tube, the quartz tube is evacuated and sealed, and the quartz tube is vertically hung in the center of a tube furnace; the raw material fragments are kept at a temperature of 893 to 1093 K for 4 to 6 hours until they reach a molten state.

4. A Bi according to claim 2 1-x Sb x A method for preparing a single crystal material, characterized in that: In step S4, the central temperature of the heating area is controlled to be 573K-773K, and the quartz tube is slowly lowered at a speed of 0.8-1.5 μm / s until the Bi 1-x Sb x The top of the multicrystalline ingot is lowered below the molten zone and melted one or more times.

5. A thermoelectric cooling device, characterized in that: Including Bi as claimed in claim 1 1-x Sb x Single crystal material.

6. A thermoelectric cooling device according to claim 5, characterized in that: Including Bi 1-x Sb x Single-stage thermoelectric cooling device or Bi 1-x Sb x Based on multi-stage thermoelectric cooling device, the Bi 1-x Sb x The multi-stage thermoelectric cooling device is composed of Bi 1-x Sb x The basic single-stage thermoelectric cooling device is obtained by cascading assembly through solder; The Bi 1-x Sb x The single-stage thermoelectric cooling device includes Bi 1-x Sb x Base single pair cooling module or Bi 1-x Sb x The Bi 1-x Sb x The refrigeration module is made of Bi 1-x Sb x The refrigeration module is assembled by soldering the Bi 1-x Sb x The base pair refrigeration module includes the Bi 1-x Sb x Single crystal material.

7. A method for preparing a thermoelectric refrigeration device according to any one of claims 5 to 6, characterized in that: The following steps are involved: a. Change Bi 1-x Sb x Single crystal material and BiSbTe material cutting to obtain Bi 1-x Sb x Single crystal thermoelectric legs and BiSbTe thermoelectric legs; b. Bi obtained in step a 1-x Sb x The single crystal thermoelectric legs and BiSbTe thermoelectric legs were sequentially washed with alkali, water, acid, and water to remove oil stains; c. Remove the oil-stained Bi obtained in step c. 1-x Sb x The single crystal thermoelectric leg and the BiSbTe thermoelectric leg are electroplated separately to obtain Bi with Ni electrode layer. 1-x Sb x Single crystal thermoelectric legs and BiSbTe thermoelectric legs; d. The Bi with Ni electrode layer obtained in step c 1-x Sb x The single crystal thermoelectric legs and BiSbTe thermoelectric legs are obtained by using Bi 0.58 Sn 0.42 The Bi 1-x Sb x Base single pair refrigeration module; e. Bi obtained in step d 1-x Sb x The Bi-based refrigeration module is assembled and cascaded by soldering. 1-x Sb x Based on multi-stage thermoelectric cooling device.

8. The method for preparing a thermoelectric refrigeration device according to claim 7, characterized in that: In step b, the alkali washing refers to washing and removing oil stains in an alkali solution containing 60-80 g / L of NaOH, 20-40 g / L of Na2CO3, 10-20 g / L of Na3PO4·12H2O and 4-8 g / L of Na2SiO3; The pickling refers to heavy washing with hydrochloric acid at a concentration of 36wt% to 38wt% to remove residual alkali solution.

9. The method for preparing a thermoelectric refrigeration device according to claim 7, characterized in that: In step c, the electroplating treatment refers to the process of electroplating a catalyst containing 200-280 g / L NiSO4·7H2O, 30-40 g / L H3BO3, 5-15 g / L NaCl, 60-80 g / L Na2SO4, 60-80 g / L MgSO4 and 0.9-1.0 g / L C 12 H 25 SO4Na plating solution at 35-55°C, 1-2.4A / cm 2 The current density is electroplated for 6 to 15 minutes.

10. An application of the thermoelectric cooling device according to any one of claims 5 to 6, characterized in that: The thermoelectric refrigeration device is suitable for low-temperature refrigeration of high-temperature superconductors.

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