Method for synthesizing Mg3 (Bi, Sb) 2-based material through ball milling

Abstract

The invention belongs to the technical field of preparation of thermoelectric semiconductor materials, and provides a method for synthesizing an Mg3 (Bi, Sb) 2-based material through ball milling in order to solve the problems that in the process of synthesizing a magnesium-based material through a ball milling method, the preparation time is long, and components are not uniform due to material cold welding caking, and the like, and the method comprises the steps that high-purity Bi particles, high-purity Sb particles and high-purity Mg chips are weighed in a glove box under the inert atmosphere; secondly, in a glove box, Bi particles and Sb particles are placed in a ball milling tank, ball milling balls with different diameters are added, and then pre-ball milling is conducted under the inert atmosphere; the preparation method comprises the following steps: pre-ball-milling Bi and Sb powder, adding Mg chips under the protection of an inert atmosphere after pre-ball-milling, fully mixing the ball-milled Bi and Sb powder with the Mg chips, and then ball-milling in the inert atmosphere to obtain the Mg3 (Bi, Sb) 2-based material. By changing the feeding sequence and optimizing the feeding particle size, the specific surface area of the powder is increased, the reaction speed of the powder and the Mg element is increased, and the phenomena of adhesion of the material and the tank wall and cold welding agglomeration are prevented, so that the material synthesis efficiency and the component uniformity are improved.

Description

Technical Field

[0001] This invention belongs to the field of thermoelectric semiconductor material preparation technology, specifically relating to a method for preparing Mg3(Bi,Sb)2-based materials by ball milling. Background Technology

[0002] Thermoelectric technology near room temperature is currently dominated by bismuth telluride-based (Bi2Te3-based) materials. However, due to the toxicity and scarcity of tellurium (Te), developing next-generation Te-free technologies is crucial for sustainable development. In recent years, Mg3(Bi,Sb)2 intermetallic compounds (i.e., the Zintl phase) have attracted widespread attention due to their non-toxicity and high elemental abundance. Increasing the Bi concentration can shift the peak zT to a lower temperature, thus facilitating near-room temperature applications. However, the highly reactive nature of elemental magnesium makes the preparation of these materials quite complex.

[0003] Currently, common preparation methods include mechanical alloying and smelting. Mechanical alloying, also known as ball milling, involves high-energy ball milling under an inert atmosphere. First, the materials are weighed according to the chemical element ratio and then fed into the machine before high-energy ball milling. The ball milling time for 10g of material can be as long as 10 hours or even longer. During high-energy ball milling, material control is necessary to prevent adhesion between the material and the milling vessel, or cold welding agglomeration, leading to compositional uniformity issues. Furthermore, prolonged milling time cannot prevent agglomeration, which also affects the subsequent material properties. Smelting is limited by the reactivity of elemental magnesium, which readily reacts with quartz tubes. Therefore, a common process uses tantalum as a container, sealing the material inside a tantalum tube, which is then sealed inside a quartz tube for high-temperature smelting. This method is relatively simple, but the preparation cost is high, and mass production poses certain safety risks. Summary of the Invention

[0004] To address the problems of long preparation time and material agglomeration due to cold welding in the synthesis of magnesium-based materials by ball milling, this invention provides a method for efficient ball milling synthesis of Mg3(Bi,Sb)2-based materials. By changing the feeding sequence, the particle size of the feed is optimized to increase the specific surface area of ​​the powder, improve the reaction rate with Mg, and prevent material adhesion to the tank wall and cold welding agglomeration, thereby improving the material synthesis efficiency and component uniformity.

[0005] The technical solution of the present invention is as follows: A method for ball milling to synthesize Mg3(Bi,Sb)2-based materials comprises the following steps: (1) Weigh out high-purity Bi particles, Sb particles and Mg shavings in a glove box under an inert atmosphere; The composition of the Mg3(Bi,Sb)2-based material is N-type Mg. 3+δ Bi x Sb 2-x–z M y N zMagnesium-based thermoelectric materials. Where x ranges from 0 to 1.6, δ ranges from 0 to 0.2, M includes Cu, Y, Sc, and La dopants, y ranges from 0 to 0.03, N includes Te, Se, and S, and Z ranges from 0 to 0.01.

[0006] Preferably, the purity of the Bi, Sb and Mg raw materials is greater than or equal to 99.99%, the purity of the admixture elements is greater than 4N, and the equivalent reagent (4N) indicates that the content of the main component is 99.99% or more.

[0007] (2) In the glove box, Bi particles and Sb particles are first placed in a ball mill jar, and ball milling balls of different diameters are added. Then, pre-ball milling is carried out under an inert atmosphere to refine the powder particles. The ball milling parameters are: ball-to-material ratio of 2-3:1, rotation speed of 600-1000 rpm / min, and ball milling time of 1-2 hours.

[0008] Preferably, the diameter of the grinding balls is ≤5mm and >0.3mm. More preferably, the diameters of the grinding balls are 5mm, 3mm, and 1mm, and the ratio of the number of grinding balls is 1-2:2-3:2-3.

[0009] Preferably, the grinding balls are made of stainless steel or zirconium oxide.

[0010] (3) After pre-ball milling, Mg chips are added under a protective atmosphere. The ball-milled Bi and Sb powders and Mg chips are thoroughly mixed and then ball-milled under an inert atmosphere to obtain Mg3(Bi,Sb)2-based material.

[0011] Preferably, the rotation speed is 600-1000 rpm / min and the grinding time is 5-10 hours.

[0012] Since the doping amount of Mg3(Bi,Sb)2-based materials is very small, there is no requirement to add doping. However, as a preferred option, the doping amount is added in step 3.

[0013] The preferred inert atmosphere is argon, while nitrogen should be avoided to prevent the reaction between nitrogen and magnesium.

[0014] After sintering the Mg3(Bi,Sb)2-based material obtained by ball milling into a bulk material, the uniformity of thermoelectric properties was significantly improved, and the thermoelectric figure of merit was increased. zT The results are improved. Preferably, the vacuum hot pressing sintering pressure is 30-80 MPa, the sintering temperature is 600-800℃, and the hot pressing sintering time is 2-10 min.

[0015] Compared with the prior art, the beneficial effects of the present invention are as follows: Since Mg has good ductility, it is difficult to ball mill it into powder alone, and it is more likely to agglomerate and be cold-welded together. Moreover, the fined magnesium powder poses a greater safety hazard in subsequent operations. Therefore, by changing the feeding sequence and pre-ball milling Bi and Sb, the particle size of the feed is optimized to increase the specific surface area of ​​the powder, improve the reaction rate with Mg, prevent the adhesion between the material and the tank wall and the cold-welded agglomeration, greatly shorten the preparation time, improve the material synthesis efficiency and component uniformity, and also improve the thermoelectric properties of the material. Attached Figure Description

[0016] Figure 1 The XRD pattern prepared for an embodiment of the present invention.

[0017] Figure 2 This is an EDS surface scan elemental distribution map prepared in Example 1 of the present invention.

[0018] Figure 3 This is an EDS surface scan elemental distribution map prepared in Comparative Example 1 of the present invention.

[0019] Figure 4 This is an EDS surface scan elemental distribution map prepared in Comparative Example 2 of the present invention. Detailed Implementation

[0020] The present invention will be further described in detail below with reference to the embodiments and accompanying drawings. The raw materials used in the synthesis method can all be commercially available or prepared by conventional methods.

[0021] Example: Synthesis of N-type Mg 3+δ Bi x Sb 2-x –z M y N z Magnesium-based thermoelectric materials, where x ranges from 0 to 1.6, δ ranges from 0 to 0.2, M includes dopants such as Cu, Y, Sc, and La, y ranges from 0 to 0.03, N includes Te, Se, and S, and Z ranges from 0 to 0.01.

[0022] Example 1: (1) Ingredients The synthetic component is Mg 3.2 Bi 1.5 Sb 0.5 Y 0.01 The N-type magnesium-based thermoelectric material weighs a total of 20g. The raw materials are Bi particles, Sb particles and Mg scrap with a purity of 99.99%, and the dopant element Y has a purity greater than 4N.

[0023] In a glove box filled with argon atmosphere, high-purity Bi particles, Sb particles, Mg scrap, and admixture element Y were weighed according to the chemical ratio shown in Table 1.

[0024] Table 1

[0025] (2) Pre-ball milling: In an argon glove box, Bi particles and Sb particles are placed in a ball milling jar and ball milling balls with diameters of 5 mm, 3 mm and 1 mm are added. The ball milling ball ratio is 1:2:2. The ball milling balls are made of stainless steel and the ball-to-material ratio is 2:1. Then, ball milling is carried out under an argon atmosphere at a speed of 800 rpm / min for 1.5 h to refine the powder particles.

[0026] (3) Material synthesis After pre-ball milling, under argon atmosphere protection, weighed Mg chips and dopant Y are added. The pre-milled BiSb powder, Mg chips, and dopant Y are first thoroughly mixed. Then, ball milling is carried out under argon atmosphere at a speed of 800 rpm / min for 6 hours to obtain Mg3(Bi,Sb)2-based material.

[0027] Example 2: (1) Ingredients The synthetic component is Mg 3.2 Bi 1.5 Sb 0.5 Y 0.01 The N-type magnesium-based thermoelectric material weighs a total of 20g. The raw materials are Bi particles, Sb particles and Mg scrap with a purity of 99.99%, and the dopant element Y has a purity greater than 4N.

[0028] In a glove box filled with argon atmosphere, high-purity Bi particles, Sb particles, and Mg scrap, as well as the dopant element Y, were weighed according to the chemical proportions shown in Table 1. (2) Pre-ball milling Inside the glove box, Bi particles and Sb particles are first placed in a ball mill jar, and then ball milling balls with diameters of 5 mm, 3 mm and 1 mm are added. The ball-to-particle ratio is 1:2:3. The ball milling balls are made of stainless steel and the ball-to-particle ratio is 3:1. Then, ball milling is carried out under an argon atmosphere at a speed of 600 rpm / min for 2 hours to refine the powder particles.

[0029] (3) Material synthesis After pre-ball milling, under a protective atmosphere, weighed Mg chips and dopant element Y are added. The pre-milled BiSb powder, Mg chips, and dopant element Y are first thoroughly mixed. Then, ball milling is carried out under an argon atmosphere at a speed of 600 rpm / min for 8 hours to obtain Mg3(Bi,Sb)2-based material.

[0030] Example 3: (1) Ingredients The synthetic component is Mg 3.2 Bi1.5 Sb 0.5 Y 0.01 The N-type magnesium-based thermoelectric material weighs a total of 20g. The raw materials are Bi particles, Sb particles and Mg scrap with a purity of 99.99%, and the dopant element Y has a purity greater than 4N.

[0031] In a glove box filled with argon atmosphere, high-purity Bi particles, Sb particles, Mg scrap, and admixture element Y were weighed according to the chemical ratio shown in Table 1.

[0032] (2) Pre-ball milling Inside the glove box, Bi particles and Sb particles are first placed in a ball mill jar, and then grinding balls with diameters of 5 mm, 3 mm and 1 mm are added. The ratio of the number of grinding balls is 1:3:2. The grinding balls are made of stainless steel, and the ball-to-particle ratio is 2:1. Then, the grinding is carried out under an argon inert atmosphere at a speed of 1000 rpm / min for 1 hour to refine the powder particles.

[0033] (3) Material synthesis After pre-ball milling, under a protective atmosphere, weighed Mg chips and dopant element Y are added. The pre-milled BiSb powder, Mg chips, and dopant element Y are first thoroughly mixed. Then, ball milling is carried out under an argon atmosphere at a speed of 1000 rpm / min for 6 hours to obtain Mg3(Bi,Sb)2-based material.

[0034] Example 4: (1) Ingredients The synthetic component is Mg 3.2 Bi 1.5 Sb 0.5 Y 0.01 The N-type magnesium-based thermoelectric material weighs a total of 20g. The raw materials are Bi particles, Sb particles and Mg scrap with a purity of 99.99%, and the dopant element Y has a purity greater than 4N.

[0035] In a glove box filled with argon atmosphere, high-purity Bi particles, Sb particles, Mg scrap, and admixture element Y were weighed according to the chemical ratio shown in Table 1.

[0036] (2) Pre-ball milling Inside the glove box, Bi particles and Sb particles are first placed in a ball mill jar, and then grinding balls with diameters of 5 mm, 4 mm, and 2 mm are added in a ratio of 1:2:2. The grinding balls are made of stainless steel, and the ball-to-particle ratio is 2:1. Then, the grinding is carried out under an argon inert atmosphere at a speed of 800 rpm / min for 1.5 hours to refine the powder particles.

[0037] (3) Material synthesis After pre-ball milling, under a protective atmosphere, weighed Mg chips and dopant element Y are added. The pre-milled BiSb powder, Mg chips, and dopant element Y are first thoroughly mixed, and then ball milled under an argon atmosphere at a speed of 800 rpm / min for 6 hours to obtain Mg3(Bi,Sb)2-based material.

[0038] Example 5: (1) Ingredients The synthetic component is Mg 3.2 Bi 1.5 Sb 0.5 Y 0.01 The N-type magnesium-based thermoelectric material weighs a total of 20g. The raw materials are Bi particles, Sb particles and Mg scrap with a purity of 99.99%, and the dopant element Y has a purity greater than 4N.

[0039] In a glove box filled with argon atmosphere, high-purity Bi particles, Sb particles, Mg scrap, and admixture element Y were weighed according to the chemical ratio shown in Table 1.

[0040] (2) Pre-ball milling Inside the glove box, Bi particles and Sb particles are first placed in a ball mill jar, and then grinding balls with diameters of 5 mm, 3 mm, and 0.5 mm are added in a ratio of 1:3:2. The grinding balls are made of stainless steel, and the ball-to-particle ratio is 2:1. Then, the grinding is carried out under an argon inert atmosphere at a speed of 1000 rpm / min for 1 hour to refine the powder particles.

[0041] (3) Material synthesis After pre-ball milling, under a protective atmosphere, weighed Mg chips and dopant element Y are added. The pre-milled BiSb powder, Mg chips, and dopant element Y are first thoroughly mixed. Then, ball milling is carried out under an argon atmosphere at a speed of 1000 rpm / min for 6 hours to obtain Mg3(Bi,Sb)2-based material.

[0042] Example 6: (1) Ingredients The synthetic component is Mg 3.2 Bi 1.5 Sb 0.5 Y 0.01 The N-type magnesium-based thermoelectric material weighs a total of 20g. The raw materials are Bi particles, Sb particles and Mg scrap with a purity of 99.99%, and the dopant element Y has a purity greater than 4N.

[0043] In a glove box filled with argon atmosphere, high-purity Bi particles, Sb particles, Mg scrap, and admixture element Y were weighed according to the chemical ratio shown in Table 1.

[0044] (2) Pre-ball milling Inside the glove box, Bi particles and Sb particles are first placed in a ball mill jar, and then ball milling balls with diameters of 4 mm, 2 mm, and 1 mm are added in a ball-to-ball ratio of 1:2:2. The ball milling balls are made of stainless steel, and the ball-to-particle ratio is 2:1. Then, ball milling is carried out under an argon inert atmosphere at a speed of 1000 rpm / min for 1 hour to refine the powder particles.

[0045] (3) Material synthesis After pre-ball milling, under a protective atmosphere, weighed Mg chips and dopant element Y are added. The pre-milled BiSb powder, Mg chips, and dopant element Y are first thoroughly mixed. Then, ball milling is carried out under an argon atmosphere at a speed of 1000 rpm / min for 6 hours to obtain Mg3(Bi,Sb)2-based material.

[0046] Example 7: (1) Ingredients The synthetic component is Mg 3.2 Bi 1.5 Sb 0.5 Y 0.01 The N-type magnesium-based thermoelectric material weighs a total of 20g. The raw materials are Bi particles, Sb particles and Mg scrap with a purity of 99.99%, and the dopant element Y has a purity greater than 4N.

[0047] In a glove box filled with argon atmosphere, high-purity Bi particles, Sb particles, Mg scrap, and admixture element Y were weighed according to the chemical ratio shown in Table 1.

[0048] (2) Pre-ball milling Inside the glove box, Bi particles and Sb particles are first placed in a ball mill jar, and then ball milling balls with diameters of 4 mm, 2 mm and 1 mm are added. The ball-to-particle ratio is 1:3:2. The ball milling balls are made of stainless steel and the ball-to-particle ratio is 3:1. Then, ball milling is carried out under an argon inert atmosphere at a speed of 800 rpm / min for 2 hours to refine the powder particles.

[0049] (3) Material synthesis After pre-ball milling, under a protective atmosphere, weighed Mg chips and dopant element Y are added. The pre-milled BiSb powder, Mg chips, and dopant element Y are first thoroughly mixed, and then ball milled under an argon atmosphere at a speed of 800 rpm / min for 9 hours to obtain Mg3(Bi,Sb)2-based material.

[0050] Example 8: (1) Ingredients The synthetic component is Mg 3.2 Bi 1.5 Sb 0.5 Y 0.01The N-type magnesium-based thermoelectric material weighs a total of 20g. The raw materials are Bi particles, Sb particles and Mg scrap with a purity of 99.99%, and the dopant element Y has a purity greater than 4N.

[0051] In a glove box filled with argon atmosphere, high-purity Bi particles, Sb particles, Mg scrap, and admixture element Y were weighed according to the chemical ratio shown in Table 1.

[0052] (2) Pre-ball milling Inside the glove box, Bi particles and Sb particles are first placed in a ball mill jar, and then ball milling balls with diameters of 5 mm, 3 mm, and 0.5 mm are added in a ball-to-ball ratio of 1:2:2. The ball milling balls are made of stainless steel, and the ball-to-particle ratio is 3:1. Then, ball milling is carried out under an argon inert atmosphere at a speed of 600 rpm / min for 2 hours to refine the powder particles.

[0053] (3) Material synthesis After pre-ball milling, under a protective atmosphere, weighed Mg chips and dopant element Y are added. The pre-milled BiSb powder, Mg chips, and dopant element Y are first thoroughly mixed, and then ball milled under an argon atmosphere at a speed of 600 rpm / min for 9 hours to obtain Mg3(Bi,Sb)2-based material.

[0054] Example 9: (1) Ingredients The synthetic component is Mg 3.2 Bi 1.5 Sb 0.5 Y 0.01 The N-type magnesium-based thermoelectric material weighs a total of 20g. The raw materials are Bi particles, Sb particles and Mg scrap with a purity of 99.99%, and the dopant element Y has a purity greater than 4N.

[0055] In a glove box filled with argon atmosphere, high-purity Bi particles, Sb particles, Mg scrap, and admixture element Y were weighed according to the chemical ratio shown in Table 1.

[0056] (2) Pre-ball milling Inside the glove box, Bi particles and Sb particles are first placed in a ball mill jar, and then grinding balls with diameters of 5 mm, 3 mm, and 0.5 mm are added in a ratio of 1:3:2. The grinding balls are made of stainless steel, and the ball-to-particle ratio is 2:1. Then, the grinding is carried out under an argon inert atmosphere at a speed of 1000 rpm / min for 1 hour to refine the powder particles.

[0057] (3) Material synthesis After pre-ball milling, under a protective atmosphere, weighed Mg chips and dopant element Y are added. The pre-milled BiSb powder, Mg chips, and dopant element Y are first thoroughly mixed. Then, ball milling is carried out under an argon atmosphere at a speed of 1000 rpm / min for 6 hours to obtain Mg3(Bi,Sb)2-based material.

[0058] Example 10: (1) Ingredients The synthetic component is Mg 3.2 Bi 1.5 Sb 0.5 Y 0.01 The N-type magnesium-based thermoelectric material weighs a total of 20g. The raw materials are Bi particles, Sb particles and Mg scrap with a purity of 99.99%, and the dopant element Y has a purity greater than 4N.

[0059] In a glove box filled with argon atmosphere, high-purity Bi particles, Sb particles, Mg scrap, and admixture element Y were weighed according to the chemical ratio shown in Table 1.

[0060] (2) Pre-ball milling Inside the glove box, Bi particles and Sb particles are first placed in a ball mill jar, and then ball milling balls with diameters of 5 mm, 2 mm, and 1 mm are added in a ball-to-ball ratio of 2:3:2. The ball milling balls are made of stainless steel, and the ball-to-particle ratio is 2:1. Then, ball milling is carried out under an argon inert atmosphere at a speed of 800 rpm / min for 1.5 hours to refine the powder particles.

[0061] (3) Material synthesis After pre-ball milling, under a protective atmosphere, weighed Mg chips and dopant element Y are added. The pre-milled BiSb powder, Mg chips, and dopant element Y are first thoroughly mixed, and then ball milled under an argon atmosphere at a speed of 800 rpm / min for 8 hours to obtain Mg3(Bi,Sb)2-based material.

[0062] Example 11: (1) Ingredients The synthetic component is Mg 3.2 Bi 1.5 Sb 0.5 Y 0.01 The N-type magnesium-based thermoelectric material weighs a total of 20g. The raw materials are Bi particles, Sb particles and Mg scrap with a purity of 99.99%, and the dopant element Y has a purity greater than 4N.

[0063] In a glove box filled with argon atmosphere, high-purity Bi particles, Sb particles, Mg scrap, and admixture element Y were weighed according to the chemical ratio shown in Table 1.

[0064] (2) Pre-ball milling Inside the glove box, Bi particles and Sb particles are first placed in a ball mill jar, and then ball milling balls with diameters of 5 mm, 3 mm, and 1 mm are added in a ball-to-particle ratio of 2:3:3. The ball milling balls are made of stainless steel, and the ball-to-particle ratio is 2:1. Then, ball milling is carried out under an argon inert atmosphere at a speed of 800 rpm / min for 1 hour to refine the powder particles.

[0065] (3) Material synthesis After pre-ball milling, under a protective atmosphere, weighed Mg chips and dopant element Y are added. The pre-milled BiSb powder, Mg chips, and dopant element Y are first thoroughly mixed, and then ball milled under an argon atmosphere at a speed of 800 rpm / min for 8 hours to obtain Mg3(Bi,Sb)2-based material.

[0066] Comparative Example 1: The difference from Example 1 is that the raw materials are ground together.

[0067] (1) Ingredients The synthetic component is Mg 3.2 Bi 1.5 Sb 0.5 Y 0.01 The N-type magnesium-based thermoelectric material weighs a total of 20g. The raw materials are Bi particles, Sb particles and Mg scrap with a purity of 99.99%, and the dopant element Y has a purity greater than 4N.

[0068] In a glove box filled with argon atmosphere, high-purity Bi particles, Sb particles, Mg scrap, and admixture element Y were weighed according to the chemical ratio shown in Table 1.

[0069] (2) Ball milling (material synthesis) In an argon-filled glove box, the weighed raw materials were added to a ball mill jar according to the chemical formula. Balls of different diameters (5 mm, 3 mm, and 1 mm) were added in a ball-to-material ratio of 1:2:2, with a ball-to-material ratio of 2:1. The mixture was then ball-milled under an argon inert atmosphere at a speed of 800 rpm for 8 hours to obtain Mg. 3.2 Bi 1.5 Sb 0.5 Y 0.01 N-type magnesium-based thermoelectric materials.

[0070] Comparative Example 2 The difference from Comparative Example 1 is that the ball milling time is increased, and a powder control step is added.

[0071] (1) Ingredients The synthetic component is Mg 3.2 Bi 1.5 Sb 0.5 Y0.01 The N-type magnesium-based thermoelectric material weighs a total of 20g. The raw materials are Bi particles, Sb particles and Mg scrap with a purity of 99.99%, and the dopant element Y has a purity greater than 4N.

[0072] In a glove box filled with argon atmosphere, high-purity Bi particles, Sb particles, Mg scrap, and admixture element Y were weighed according to the chemical ratio shown in Table 1.

[0073] (2) Ball mill In an argon-filled glove box, the weighed raw materials were added to a ball mill jar according to the chemical formula. Balls of different diameters (5 mm, 3 mm, and 1 mm) were added in a ball-to-material ratio of 1:2:2. The ball-to-material ratio was 2:1. The mixture was then ball-milled under an argon inert atmosphere at a speed of 800 rpm for 15 hours to obtain Mg. 3.2 Bi 1.5 Sb 0.5 Y 0.01 N-type magnesium-based thermoelectric materials.

[0074] (3) Powder control During step 2, the powder needs to be controlled every hour of ball milling. If the powder adheres to the wall of the ball mill, it must be separated from the ball mill bismuth to prevent the material from agglomerating and cold welding during subsequent ball milling, which would result in uneven composition.

[0075] Comparative Example 3 Unlike Example 1, the ball milling time in step 3 is too long.

[0076] (1) Ingredients The synthetic component is Mg 3.2 Bi 1.5 Sb 0.5 Y 0.01 The N-type magnesium-based thermoelectric material weighs a total of 20g. The raw materials are Bi particles, Sb particles and Mg scrap with a purity of 99.99%, and the dopant element Y has a purity greater than 4N.

[0077] In a glove box filled with argon atmosphere, high-purity Bi particles, Sb particles, Mg scrap, and admixture element Y were weighed according to the chemical ratio shown in Table 1.

[0078] (2) Pre-ball milling Inside an argon glove box, Bi and Sb particles are first placed in a ball mill jar, and grinding balls with diameters of 5 mm, 3 mm, and 1 mm are added in a ratio of 1:2:2. The grinding balls are made of stainless steel, and the ball-to-particle ratio is 2:1. Then, the grinding is carried out under an argon atmosphere at a speed of 800 rpm / min for 1.5 hours to refine the powder particles.

[0079] (3) Material synthesis After pre-ball milling, under argon atmosphere protection, weighed Mg chips and Y dopant were added. The pre-milled BiSb powder, Mg chips, and Y dopant were first thoroughly mixed, and then ball milled under argon atmosphere at a speed of 800 rpm / min for 13.5 h to obtain Mg3(Bi,Sb)2-based material.

[0080] Test case The magnesium-based material powders (three parallel samples) prepared in Examples 1 and Comparative Examples 2 and 3 were fed into a mold and held at a pressure of 50 MPa and a sintering temperature of 700 °C for 5 min to obtain a bulk material. The bulk material at room temperature (298 K) was tested and calculated. zT The values ​​and results are shown in Table 2 below. Because the raw materials for Comparative Example 1 were ground together, the ball milling time was relatively shortened, as shown in the attached table. Figure 3 As shown, the material synthesis failed and the composition was very uneven, so Table 2 does not include the sample of Comparative Example 1.

[0081] Table 2. Results of the thermoelectric figure of merit for the bulk material.

[0082] As shown in Table 2 above and as follows Figure 1 , Figure 2 , Figure 4 As shown, Comparative Example 2 is without pre-ball milling of Bi,Sb. Due to the long milling time, there are differences in the composition of the EDS test. However, after pre-ball milling of Bi,Sb in Example 1, the material composition is more uniform. Therefore, the thermoelectric figure of merit of the bismuth telluride bulk obtained in Comparative Example 2 is 0.72 (mean), and the zT value of the bulk has a large fluctuation.

[0083] As shown in Table 2 above and as follows Figure 1 , Figure 2 As shown, the zT values ​​of Example 1 and Comparative Example 3 are improved, and the fluctuation of zT values ​​is reduced. However, the material performance of Comparative Example 3 is lower than that of Example 1. This is because the grinding time is extended, and agglomeration still occurs, resulting in an increase in material particle size and adversely affecting material performance. When Bi and Sb are not pre-ball-milled, and the grinding time remains unchanged.

[0084] like Figure 1 and Figure 3 As shown, XRD testing of the material in Comparative Example 1 indicates that the grinding time was short and the Bi elemental peak was still present, indicating that the material synthesis failed.

[0085] The above results all indicate that preparing magnesium-based materials by distributed ball milling improves the preparation efficiency by 50%, results in more uniform material properties, and increases the thermoelectric zT by 10%.

[0086] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make some modifications or alterations to the above-disclosed technical content to create equivalent embodiments without departing from the scope of the present invention. Any simple modifications, equivalent changes, and alterations made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the scope of the present invention.

Claims

1. A method for ball milling to synthesize Mg3(Bi,Sb)2-based materials, characterized in that, The synthesis method comprises the following steps: (1) Weigh high-purity Bi particles, Sb particles and Mg shavings in a glove box under an inert atmosphere; (2) In the glove box, Bi particles and Sb particles are first placed in the ball milling jar, and ball milling balls of different diameters are added. Then, pre-ball milling is carried out under an inert atmosphere. (3) After pre-ball milling, Mg chips are added under an inert atmosphere to fully mix the ball-milled Bi and Sb powders with Mg chips, and then ball milling is performed under an inert atmosphere to obtain Mg3(Bi,Sb)2-based material.

2. The method for ball milling to synthesize Mg3(Bi,Sb)2-based materials according to claim 1, characterized in that, The composition of the Mg3(Bi,Sb)2-based material is Mg 3+δ Bi x Sb 2-x–z M y N z Magnesium-based thermoelectric materials.

3. The method for ball milling to synthesize Mg3(Bi,Sb)2-based materials according to claim 2, characterized in that, In the magnesium-based thermoelectric material composition, x ranges from 0 to 1.6, δ ranges from 0 to 0.2, M includes Cu, Y, Sc, and La dopants, y ranges from 0 to 0.03, and N includes Te, Se, S, and Z ranges from 0 to 0.

01.

4. The method for ball milling to synthesize Mg3(Bi,Sb)2-based materials according to claim 1, 2, or 3, characterized in that: The purity of the Bi, Sb and Mg raw materials is greater than or equal to 99.99%, and the purity of the admixture elements is greater than 4N.

5. The method for ball milling to synthesize Mg3(Bi,Sb)2-based materials according to claim 1, characterized in that: The ball milling parameters in step 2 are: ball-to-material ratio of 2-3:1, rotation speed of 600-1000 rpm / min, and ball milling time of 1-2 hours.

6. The method for ball milling to synthesize Mg3(Bi,Sb)2-based materials according to claim 1 or 5, characterized in that: The diameter of the grinding ball should be ≤5mm and >0.3mm.

7. The method for ball milling to synthesize Mg3(Bi,Sb)2-based materials according to claim 6, characterized in that: The grinding balls are made of stainless steel or zirconium oxide.

8. The method for ball milling to synthesize Mg3(Bi,Sb)2-based materials according to claim 1, characterized in that: In step 3, the ball milling speed is 600-1000 rpm / min, and the grinding time is 5-10 hours.

9. The method for ball milling to synthesize Mg3(Bi,Sb)2-based materials according to claim 1, characterized in that: The inert gas is selected from argon.

10. The method for ball milling to synthesize Mg3(Bi,Sb)2-based materials according to claim 1, characterized in that: The conditions for sintering the Mg3(Bi,Sb)2-based material obtained by ball milling into a bulk material are as follows: vacuum hot pressing sintering pressure is 30-80 MPa, sintering temperature is 600-800℃, and hot pressing sintering time is 2-10 min.

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