A method for preparing lead telluride powder

Abstract

The present invention provides a method for preparing lead telluride powder, comprising the following steps: S1, ball-milling lead powder and tellurium powder to uniformly mix to obtain a mixed raw material; the particle size of the lead powder and tellurium powder can pass through a 200-mesh sieve; S2, placing the mixed raw material in a horizontal tube furnace, introducing a protective gas into the tube furnace to replace the air; S3, after the gas replacement is completed, stopping the introduction of the protective gas, then introducing hydrogen, and heating the mixture to 270-300°C for a heat-insulating reaction; S4, after the heat-insulating reaction is completed, cooling the mixture to obtain the lead telluride powder. The preparation method of the present invention is simple to operate, and by controlling the raw material particle size and reaction temperature, a one-step synthesis reaction is performed to obtain lead telluride powder, without the need for crushing, resulting in a fast synthesis and high yield. The method is also short in process, low in cost, safe, environmentally friendly, and suitable for industrial application.

Description

Technical Field

[0001] The present invention belongs to the technical field of semiconductor material preparation, and in particular relates to a method for preparing lead telluride powder. Background Art

[0002] Lead telluride (PbTe) is a semiconductor material composed of the Group IVA element Pb and the Group VIA element Te. Its molecular formula is PbTe, and its band gap is 0.31 eV at room temperature, exhibiting a direct-transition band structure. It exhibits significant thermoelectric and infrared photoconductive properties, making it suitable for the manufacture of thermoelectric converters (refrigerators, generators, heat sources), infrared detectors, and tunnel diodes. It is also increasingly being used in the thin-film solar energy field, and its applications are expected to expand in the future.

[0003] Existing common methods for preparing lead telluride powder include: 1. Chemical synthesis under wet conditions, which has disadvantages such as low product purity and difficulty in wastewater treatment; 2. Vacuum melting to synthesize lead telluride blocks under pyrometallurgical conditions, and then crushing them into powder. Most of these methods have problems such as high energy consumption, high equipment requirements, and long process flows.

[0004] Chinese patent CN114524417A discloses a high-yield lead telluride production method, which includes placing Pb and Te blocks into a rotating, high-temperature, high-pressure synthesis furnace. After inert gas replacement, a certain pressure of inert gas is introduced. The reaction is then heated to 500-600°C under rotating conditions for a reaction, then to 1050-1100°C for a reaction. The resulting lead telluride composite is crushed into particles less than 3 mm in size, then heated to 700-800°C for a reaction, followed by a continuous introduction of hydrogen for a reaction, followed by cooling to obtain the lead telluride product. This method requires a high-pressure synthesis furnace, high equipment requirements, and involves the steps of synthesis, discharging, hydrogenation, and discharging. This is cumbersome, lengthy, and energy-intensive. For example, CN106252499B discloses a method for producing PbTe powder, comprising mixing Pb and Te in a 1:1 molar ratio, sealing the resulting powder in a vacuum quartz tube, smelting it in a muffle furnace, and grinding the smelted product to obtain PbTe powder. This method requires high-temperature vacuum melting, which has disadvantages such as high energy consumption, the need for grinding the resulting product, high equipment requirements, and a lengthy process.

[0005] CN101602495A discloses a method for preparing lead telluride nanocrystals and microcrystals. The method uses soluble lead salts and tellurium-containing compounds as raw materials, an alkali metal borohydride as a reducing agent, and a mixed hydroxide as a reaction medium. By controlling the reaction time at 170-200°C under normal pressure, PbTe nanocrystals and microcrystals with different morphologies are prepared. This preparation method is simple, economical, rapid, and amenable to industrial production. The synthesized products have good crystallinity, high purity, and a clean and smooth surface. However, this method has drawbacks such as the need to add a large amount of auxiliary materials and difficulty in handling by-products. Summary of the Invention

[0006] To solve the above problems, the present invention provides a method for preparing lead telluride powder.

[0007] In response to the above technical problems, the following solutions are proposed:

[0008] A method for preparing lead telluride powder, comprising:

[0009] S1. Ball-milling lead powder and tellurium powder to obtain a mixed raw material; the particle size of the lead powder and tellurium powder can pass through a 200-mesh sieve;

[0010] S2. placing the mixed raw material in a horizontal tube furnace, and introducing protective gas into the tube furnace to replace the air;

[0011] S3. After the gas replacement is completed, stop introducing nitrogen, then introduce hydrogen, and raise the temperature to 270-300°C for insulation reaction;

[0012] S4. After the heat preservation reaction is completed, cool down to obtain the product.

[0013] Preferably, in step S1, the ball milling and mixing uniformly includes: after adding the materials into the ball mill jar, introducing protective gas into the ball mill jar body to replace the air in the jar body and sealing the jar body, and then rotating and mixing the ball mill jar in the ball mill for more than 30 minutes.

[0014] Preferably, in step S1, the rotation speed of the ball mill is 30-60 r / min; and the volume of the material in the ball mill jar does not exceed 1 / 3 of the volume of the ball mill jar.

[0015] Preferably, in step S3, the hydrogen introduction rate is 1-10 L / min. If the hydrogen introduction rate is too low, impurities are likely to appear in the final product, and if the introduction rate is too high, powder will be taken away, reducing the yield.

[0016] Preferably, in step S3, the insulation reaction time is 3-6 hours. If the insulation time is too short, impurities will appear.

[0017] Preferably, in step S3, the heating rate is 12-16°C / min.

[0018] Preferably, in step S1, the mass ratio of the lead powder to the tellurium powder is 0.616-0.62:1.

[0019] Preferably, in step S2, the gas replacement time is 30-60 min; the introduction rate of the protective gas is 4-5 L / min; the protective gas is nitrogen and / or an inert gas; the inert gas can be optional, for example, conventional argon can be selected.

[0020] Preferably, in step S4, the cooling is as follows: first cooling to below 100° C., switching hydrogen to nitrogen and / or inert gas, and then taking the product out of the furnace after the cooling is completed.

[0021] Preferably, in step S4, after switching to nitrogen and / or inert gas, the filling rate of nitrogen and / or inert gas is 1-5 L / min.

[0022] Preferably, in step S2, the mixed raw material is first placed in a graphite crucible, and then the graphite crucible is placed in a horizontal tube furnace.

[0023] Compared with the prior art, the present invention has the following beneficial effects:

[0024] 1. The present invention achieves a one-step synthesis of lead telluride powder by uniformly mixing fine-particle tellurium powder with lead powder under the action of reducing gas hydrogen while controlling the reaction temperature. The preparation method is simple to operate, and by controlling the particle size of the raw materials and the reaction temperature, a one-step synthesis reaction yields lead telluride powder without the need for crushing, resulting in rapid synthesis and high yield.

[0025] 2. This method has short process, low cost, safety, environmental friendliness and is suitable for industrial application. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 The present invention is a process flow chart of the preparation method of lead telluride powder. DETAILED DESCRIPTION

[0027] A method for preparing lead telluride powder, comprising:

[0028] S1. Mixing lead powder and tellurium powder by ball milling until uniform, wherein the particle size of the lead powder and tellurium powder may exceed 200 mesh, to obtain a mixed raw material;

[0029] S2, placing the mixed raw material in a horizontal tube furnace, and introducing protective gas into the tube furnace for gas replacement;

[0030] S3. After the gas replacement is completed, stop introducing the protective gas, then introduce hydrogen, and raise the temperature to 270-300°C for insulation reaction;

[0031] S4. After the heat preservation reaction is completed, cool down to obtain the product.

[0032] In some preferred embodiments, the insulation temperature is further preferably 275°C-295°C, for example, it can be 276°C, 277°C, 278°C, 279°C, 280°C, 281°C, 282°C, 283°C, 284°C, 285°C, 286°C, 287°C, 288°C, 289°C, 290°C, 291°C, 292°C, 293°C, 294°C, etc.

[0033] In some preferred embodiments, in step S1, the ball milling and mixing uniformly includes: after adding the material to the ball mill jar, introducing protective gas into the ball mill jar body to replace the air in the jar body and sealing the jar body, and then rotating and mixing the ball mill jar in the ball mill for more than 30 minutes, further preferably, the mixing time is more than 40 minutes, and further preferably, more than 50 minutes or even more than 60 minutes.

[0034] In some embodiments, the protective gas is nitrogen, or an inert gas such as argon. The protective gas may be introduced at a rate of 5-10 L / min for 5-10 min.

[0035] In some preferred embodiments, in step S1, the rotation speed of the ball mill is 30-60 r / min.

[0036] In some preferred embodiments, the volume of the material in the ball mill does not exceed 1 / 3 of the volume of the ball mill.

[0037] In some preferred embodiments, in step S3, the hydrogen introduction rate is 1-10 L / min, which is too high.

[0038] In some preferred embodiments, in step S3, the insulation reaction time is 3-6 hours. If the insulation time is too short, impurities will appear.

[0039] In some preferred embodiments, in step S3, the heating rate is 12-16°C / min.

[0040] In some preferred embodiments, in step S1, the mass ratio of the lead powder to the tellurium powder is 0.616-0.62:1.

[0041] In some preferred embodiments, in step S2, the gas replacement time is 30-60 min; the introduction rate of the protective gas is 4-5 L / min; the protective gas is nitrogen and / or an inert gas; the inert gas can be optional, for example, conventional argon can be selected.

[0042] In some preferred embodiments, in step S4, the cooling is as follows: first cooling to below 100° C., switching hydrogen to nitrogen and / or inert gas, and then taking the product out of the furnace after the cooling is completed.

[0043] In some preferred embodiments, in step S4, after switching to nitrogen and / or inert gas, the filling rate of nitrogen and / or inert gas is 1-5 L / min.

[0044] In some preferred embodiments, in step S2, the mixed raw materials are first placed in a graphite crucible, and then the graphite crucible is placed in a horizontal tube furnace.

[0045] The present invention will be further described below in conjunction with specific examples and accompanying drawings, but the present invention is not limited to the following examples. Unless otherwise defined, all professional terms used hereinafter have the same meanings as those commonly understood by those skilled in the art. The professional terms used herein are only for the purpose of describing specific embodiments and are not intended to limit the scope of protection of the present invention.

[0046] The experimental methods described in the following examples are conventional methods unless otherwise specified; the reagents and materials are commercially available unless otherwise specified.

[0047] Example 1

[0048] A method for preparing lead telluride powder comprises:

[0049] (1) Take 61.6 g of tellurium powder and 100 g of lead powder of a particle size that can pass through a 200-mesh sieve, first put the materials into a ball mill jar with a volume ratio of material to jar body of 1 / 3, then extend the air pipe into the interior of the jar body without contacting the materials, and introduce nitrogen at a rate of 5 L / min for 5 minutes, remove the air pipe, seal the jar mouth, and then rotate the jar in a ball mill at a rotation rate of 30 r / min for 60 minutes to obtain a tellurium-lead mixture.

[0050] (2) Place the above mixture block into a graphite crucible, the amount of which should not exceed the total volume of the crucible, and then place the graphite crucible into a horizontal tube furnace.

[0051] (3) N2 replacement gas was introduced into the horizontal tube furnace at a rate of 4 L / min for 60 min.

[0052] (4) Turn off the nitrogen, introduce hydrogen at a rate of 1 L / min, then increase the temperature to 270°C at a rate of 12°C / min and keep warm for 3 h.

[0053] (5) Stop keeping warm, turn off the hydrogen when the temperature drops below 100°C, and switch to nitrogen at a rate of 1L / min. After the temperature drops to room temperature, take the product out of the furnace.

[0054] Example 2

[0055] A method for preparing lead telluride powder comprises:

[0056] (1) Take 62g of tellurium powder and 100g of lead powder that can pass through a 200-mesh sieve and place them in a ball mill with a volume ratio of 1 / 3 between the material and the jar. Then, insert a gas pipe into the jar without contacting the material and introduce nitrogen at a rate of 10L / min for 10min. Remove the gas pipe, seal the jar mouth, and then mill the mixture in a ball mill at a rotation rate of 60r / min for 30min. This will give a tellurium-lead mixture.

[0057] (2) Place the above mixture block into a graphite crucible, the amount of which should not exceed the total volume of the crucible, and then place the graphite crucible into a horizontal tube furnace.

[0058] (3) Argon was introduced into the horizontal tube furnace at a rate of 5 L / min to replace the gas for 30 min.

[0059] (4) Turn off the nitrogen, introduce hydrogen at a rate of 10 L / min, then increase the temperature to 300 °C at a rate of 16 °C / min and keep warm for 6 h.

[0060] (5) Stop keeping warm, turn off the hydrogen when the temperature drops below 100°C, and switch to argon at a rate of 5L / min. After it drops to room temperature, take it out of the furnace to obtain the product.

[0061] Example 3

[0062] A method for preparing lead telluride powder comprises:

[0063] (1) Take 61.8 g of tellurium powder and 100 g of lead powder that can pass through a 200-mesh sieve, first put the materials into a ball mill, with the volume ratio of the material to the tank being 1 / 3, then extend the air pipe into the interior of the tank without contacting the materials, and pass nitrogen at a rate of 8 L / min for 8 minutes. Remove the air pipe, seal the tank mouth, and then rotate and mix in the ball mill at a rotation rate of 50 r / min for 50 minutes to obtain a tellurium-lead mixture.

[0064] (2) Place the above mixture block into a graphite crucible, the amount of which should not exceed the total volume of the crucible, and then place the graphite crucible into a horizontal tube furnace.

[0065] (3) N2 replacement gas was introduced into the horizontal tube furnace at a rate of 5 L / min for 50 min.

[0066] (4) Turn off the nitrogen, introduce hydrogen at a rate of 5 L / min, then increase the temperature to 290°C at a rate of 14°C / min and keep warm for 5 h.

[0067] (5) Stop keeping warm, turn off the hydrogen when the temperature drops below 100°C, and switch to nitrogen at a rate of 3L / min. After the temperature drops to room temperature, take the product out of the furnace.

[0068] Comparative Example 1

[0069] The only difference between this comparative example and Example 1 is that, in step (1), the tellurium powder and the lead powder are below a 150-mesh sieve, and the tellurium powder and the lead powder are above a 200-mesh sieve.

[0070] Comparative Example 2

[0071] The only difference between this comparative example and Example 2 is that in step (1), the mixing time is 20 min.

[0072] Comparative Example 3

[0073] The only difference between this comparative example and Example 2 is that step (3) is to heat the temperature to 265°C and then keep the temperature.

[0074] Comparative Example 4

[0075] The only difference between this comparative example and Example 2 is that step (3) is heating to 305°C and then keeping the temperature.

[0076] The product yield, oxygen content, free tellurium and free lead indicators of the above examples and comparative examples were tested, and the results are shown in Table 1 below.

[0077]

[0078] As can be seen from the results in Table 1, the present invention can significantly reduce the oxygen content and the free tellurium content by controlling the particle size of the raw materials, the mixing time, and the synthesis temperature and time. The above technical solutions can significantly improve the quality of lead telluride products.

[0079] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present invention. These improvements and modifications should also be regarded as within the scope of protection of the present invention.

Claims

1. A method for preparing lead telluride powder, characterized in that: include: S1. Ball-milling lead powder and tellurium powder to obtain a mixed raw material; the particle size of the lead powder and tellurium powder can pass through a 200-mesh sieve; S2, placing the mixed raw materials in a horizontal tube furnace, and introducing protective gas into the tube furnace to replace the air; S3. After the gas replacement is completed, stop introducing the protective gas, then introduce hydrogen, and raise the temperature to 270-300°C for insulation reaction; the insulation reaction time is 3-6 hours; S4, after the heat preservation reaction is completed, the temperature is lowered to obtain; In step S1, the ball milling and mixing comprises: adding the materials into the ball mill, introducing protective gas into the ball mill to replace the air in the ball mill and sealing the ball mill, and then rotating the ball mill in the ball mill for more than 30 minutes; In step S1, the rotation speed of the ball mill is 30-60 r / min; the volume of the material in the ball mill does not exceed 1 / 3 of the volume of the ball mill; In step S1, the mass ratio of the lead powder to the tellurium powder is 0.616-0.62:

1.

2. The method for preparing lead telluride powder according to claim 1, wherein: In step S3, the hydrogen is introduced at a rate of 1-10 L / min.

3. The method for preparing lead telluride powder according to claim 1 or 2, wherein: In step S3, the heating rate is 12-16°C / min.

4. The method for preparing lead telluride powder according to claim 1, wherein: In step S2, the time for replacing the protective gas is 30-60 min; the introduction rate of the protective gas is 4-5 L / min; and the protective gas is nitrogen and / or an inert gas.

5. The method for preparing lead telluride powder according to claim 1, wherein: In step S4, the cooling is as follows: firstly cooling to below 100° C., switching hydrogen to nitrogen and / or inert gas, and then taking the product out of the furnace after the cooling is completed.

6. The method for preparing lead telluride powder according to claim 5, wherein: In step S4, after switching to nitrogen and / or inert gas, the filling rate of nitrogen and / or inert gas is 1-5 L / min.

7. The method for preparing lead telluride powder according to claim 1 or 2, wherein: In step S2, the mixed raw material is first placed in a graphite crucible, and then the graphite crucible is placed in a horizontal tube furnace.

Images