High-purity tin selenide and preparation method thereof

Abstract

The invention belongs to the technical field of tin selenide preparation, and discloses high-purity tin selenide and a preparation method thereof.The preparation method of the high-purity tin selenide comprises the following steps that 1, selenium simple substances and tin simple substances are heated to react in the inert gas atmosphere, and a tin selenide ingot is synthesized; step 2, crushing the tin selenide ingot into powder; 3, the powder is heated to 400-500 DEG C under the protection of inert gas, heat preservation is conducted for 4-5 h, and tin selenide powder is obtained; the molar ratio of the elemental selenium to the elemental tin is (1.05-1.1): 1. According to the preparation method of the high-purity tin selenide, synthesized tin selenide powder is subjected to heat preservation treatment at the temperature of 400-500 DEG C in the step 3, so that the problem that free selenium remains in the tin selenide powder can be effectively solved, and the purity of the tin selenide powder is improved.

Description

Technical Field

[0001] The invention relates to the technical field of tin selenide preparation, in particular to high-purity tin selenide. Background Art

[0002] Tin selenide is a semiconductor material with excellent photoelectric properties and thermal stability. It is easy to prepare, low in cost, and abundant in resources. It has broad application prospects in optoelectronic devices, solar cells, and electronic devices.

[0003] The synthesis methods of tin selenide mainly include direct synthesis method and vapor deposition method; among them, the direct synthesis method is the most commonly used method, which obtains tin selenide by directly combining tin and selenium at high temperature. However, there is a problem with the direct synthesis method, that is, the volatilization rate of selenium at high temperature is very fast, resulting in excessive loss of selenium and a decrease in the yield of tin selenide; therefore, the direct synthesis method will reduce the volatilization of selenium by controlling the synthesis temperature.

[0004] For example, prior art 1: Chinese patent application 202010710025.6 discloses a tin selenide-based thermoelectric material, its preparation method and application. The preparation method of the tin selenide-based thermoelectric material at least includes: placing raw materials containing Sn source, A source, M source, Se source and N source under vacuum conditions, melting and cooling to obtain powder; sintering the powder at high temperature to obtain the tin selenide-based thermoelectric material.

[0005] Prior art 1 prepares tin selenide materials doped with other elements. The specification of prior art 1 also discloses a melting temperature of 900-950°C; a melting time of 2-5h, and a high-temperature sintering condition of: maintaining at 360-560°C for 3-60min; indicating that prior art 1 is synthesized by high-temperature melting and then sintering at 360-560°C; this method is a good method for preparing tin selenide-based thermoelectric materials, but a problem will arise in the preparation of pure tin selenide, that is, the loss of selenium caused by the high temperature is not avoided during the high-temperature melting process.

[0006] Based on this, the existing technology generally adds excessive selenium to synthesize tin selenide to avoid the yield of tin selenide being insufficient. However, this will result in excessive free selenium and reduced purity of tin selenide, which cannot meet the needs of customers with high performance requirements. Summary of the invention

[0007] One of the purposes of the present invention is to provide a method for preparing high-purity tin selenide, which can improve the purity of tin selenide while improving the yield of tin selenide, and avoid excessive free selenium or the presence of free selenium affecting the quality of the product.

[0008] Another object of the present invention is to provide a high-purity tin selenide, which contains extremely low amounts of free selenium and free tin and can meet the high performance requirements of customers.

[0009] To achieve the above object, the present invention provides a method for preparing high-purity tin selenide, comprising the following steps:

[0010] Step 1: In an inert gas atmosphere, a selenium element and a tin element are subjected to a temperature-raising reaction to synthesize a tin selenide ingot;

[0011] Step 2: crushing the tin selenide ingot into powder;

[0012] Step 3: heating the powder to 400-500° C. under inert gas protection and keeping the temperature for 4-5 hours to obtain tin selenide powder;

[0013] The molar ratio of the selenium element to the tin element is 1.05-1.1:1.

[0014] In the technical scheme of the present invention, under the condition of a limited ratio of selenium and tin, the technical scheme of the present invention can be achieved by completing step 1 using a direct synthesis method commonly used in the prior art. The key step of the technical scheme of the present invention lies in step 3. The present invention performs a heat preservation treatment at 400-500° C. after the synthesis of the tin selenide powder in step 3, and finds that the problem of free selenium remaining in the tin selenide powder can be effectively solved, thereby improving the purity of the tin selenide powder.

[0015] Further, in order to improve the yield of tin selenide, the specific operation of step 1 is:

[0016] Step 11: Place the selenium block and the tin block into a graphite crucible, and then place it into a high-temperature and high-pressure furnace and evacuate to <5*10 - 4 Pa, introduce inert gas to a pressure of 1-2MPa;

[0017] Step 12: Raise the temperature to 300-400°C and keep warm for 30-60 minutes;

[0018] Step 13: Continue to increase the temperature and introduce inert gas, and perform heat and pressure treatment at a temperature of 900-950° C. and a pressure of 4-5 MPa for 150-180 min to obtain a tin selenide ingot.

[0019] Preferably, the heating rate of step 12 is 10-15°C / min.

[0020] Preferably, the heating rate of step 13 is 5-10°C / min.

[0021] Furthermore, the powder particle size obtained in step 2 is less than 3 mm.

[0022] Furthermore, the specific operation of step 3 is: putting the powder into a tubular atmosphere furnace, continuously introducing inert gas protection at a flow rate of 3-5 L / min, and then heating to 400-500° C. and keeping the temperature for 4-5 hours to obtain tin selenide powder.

[0023] The invention also discloses high-purity tin selenide, which is prepared by adopting the above-mentioned preparation method of high-purity tin selenide.

[0024] Beneficial Effects

[0025] Compared with the prior art, the present invention discloses a method for preparing high-purity tin selenide. The problem of free selenium remaining in the tin selenide powder can be effectively solved by heat-treating the synthesized tin selenide powder at 400-500° C. in step 3, thereby improving the purity of the tin selenide powder. DETAILED DESCRIPTION

[0026] The present invention will be further described below in conjunction with the embodiments, but it does not constitute any limitation to the present invention. Any limited number of modifications made within the scope of the claims of the present invention are still within the scope of the claims of the present invention.

[0027] In order to explain the technical content of the present invention in detail, further description is given below in conjunction with the implementation modes.

[0028] Example 1

[0029] A high-purity tin selenide is prepared by the following steps:

[0030] Step 11: Put the selenium block and the tin block in a graphite crucible in a molar ratio of 1.1:1, weigh the selenium block to get 869g and the tin block to get 1187g, then put it in a high temperature and high pressure furnace and evacuate to <5*10 -4 Pa, introduce nitrogen to a pressure of 2MPa;

[0031] Step 12: heating to 400°C at a heating rate of 15°C / min and heat preservation for 50 minutes;

[0032] Step 13: Continue to increase the temperature at a heating rate of 5° C. / min and introduce nitrogen, and perform heat and pressure treatment at a temperature of 950° C. and a pressure of 5 MPa for 150 min to obtain a tin selenide ingot;

[0033] Step 2: crush the tin selenide ingot and sieve it to obtain a powder with a particle size of less than 3 mm;

[0034] Step 3: Place the powder into a tubular atmosphere furnace, continuously introduce nitrogen protection at a flow rate of 5 L / min, and then raise the temperature to 500° C. and keep it for 4 hours to obtain 1975 g of tin selenide powder.

[0035] Example 2

[0036] A high-purity tin selenide is prepared by the following steps:

[0037] Step 11: Put the selenium block and the tin block in a graphite crucible in a molar ratio of 1.05:1, weigh the selenium block to get 829g and the tin block to get 1187g, then put it in a high temperature and high pressure furnace and evacuate to <5*10 -4 Pa, introduce nitrogen to a pressure of 1MPa;

[0038] Step 12: heating to 350°C at a heating rate of 10°C / min and heat preservation for 60 minutes;

[0039] Step 13: Continue to increase the temperature at a heating rate of 8° C. / min and introduce nitrogen, and perform heat and pressure treatment at a temperature of 920° C. and a pressure of 5 MPa for 180 min to obtain a tin selenide ingot;

[0040] Step 2: crush the tin selenide ingot and sieve it to obtain a powder with a particle size of less than 3 mm;

[0041] Step 3: The powder was placed in a tubular atmosphere furnace, nitrogen was continuously introduced at a flow rate of 3 L / min for protection, and then the temperature was raised to 450° C. and kept for 5 h to obtain 1973 g of tin selenide powder.

[0042] Example 3

[0043] A high-purity tin selenide is prepared by the following steps:

[0044] Step 11: Put the selenium block and the tin block in a graphite crucible in a molar ratio of 1.05:1, weigh the selenium block to get 829g and the tin block to get 1187g, then put it in a high temperature and high pressure furnace and evacuate to <5*10 -4 Pa, introduce nitrogen to a pressure of 1.5 MPa;

[0045] Step 12: heating to 300°C at a heating rate of 15°C / min and heat preservation for 60 minutes;

[0046] Step 13: Continue to increase the temperature at a heating rate of 5°C / min and introduce nitrogen, and perform heat and pressure treatment at a temperature of 900°C and a pressure of 4Mpa for 160min to obtain a tin selenide ingot;

[0047] Step 2: crush the tin selenide ingot and sieve it to obtain a powder with a particle size of less than 3 mm;

[0048] Step 3: The powder was placed in a tubular atmosphere furnace, nitrogen was continuously introduced at a flow rate of 3 L / min for protection, and then the temperature was raised to 500° C. and kept for 5 h to obtain 1974 g of tin selenide powder.

[0049] Comparative Example 1

[0050] A high-purity tin selenide is prepared by the following steps:

[0051] Step 11: Put the selenium block and the tin block in a graphite crucible in a molar ratio of 1.1:1, weigh the selenium block to get 869g and the tin block to get 1187g, then put it in a high temperature and high pressure furnace and evacuate to <5*10 -4 Pa, introduce nitrogen to a pressure of 2MPa;

[0052] Step 12: heating to 400°C at a heating rate of 15°C / min and heat preservation for 50 minutes;

[0053] Step 13: Continue to increase the temperature at a heating rate of 5° C. / min and introduce nitrogen, and perform heat and pressure treatment at a temperature of 950° C. and a pressure of 5 MPa for 150 min to obtain a tin selenide ingot;

[0054] Step 2: Crush and sieve the tin selenide ingot to obtain 2050 g of tin selenide powder with a particle size of less than 3 mm.

[0055] Comparative Example 2

[0056] A high-purity tin selenide is prepared by the following steps:

[0057] Step 11: Put the selenium block and the tin block in a molar ratio of 1:1 into a graphite crucible, weigh the selenium block to be 789.6g and the tin block to be 1187g, then put it into a high temperature and high pressure furnace and evacuate to <5*10 -4 Pa, introduce nitrogen to a pressure of 2MPa;

[0058] Step 12: heating to 400°C at a heating rate of 15°C / min and heat preservation for 50 minutes;

[0059] Step 13: Continue to increase the temperature at a heating rate of 5° C. / min and introduce nitrogen, and perform heat and pressure treatment at a temperature of 950° C. and a pressure of 5 MPa for 150 min to obtain a tin selenide ingot;

[0060] Step 2: crush the tin selenide ingot and sieve it to obtain a powder with a particle size of less than 3 mm;

[0061] Step 3: The powder was placed in a tubular atmosphere furnace, nitrogen was continuously introduced at a flow rate of 5 L / min for protection, and then the temperature was raised to 500° C. and kept for 4 h to obtain 1960 g of tin selenide powder.

[0062] Comparative Example 3

[0063] A high-purity tin selenide is prepared by the following steps:

[0064] Step 11: Put the selenium block and the tin block in a graphite crucible in a molar ratio of 1.1:1, weigh the selenium block to get 869g and the tin block to get 1187g, then put it in a high temperature and high pressure furnace and evacuate to <5*10 -4 Pa, introduce nitrogen to a pressure of 2MPa;

[0065] Step 12: heating to 400°C at a heating rate of 15°C / min and heat preservation for 50 minutes;

[0066] Step 13: Continue to increase the temperature at a heating rate of 5°C / min and introduce nitrogen, and perform heat and pressure treatment at a temperature of 800°C and a pressure of 5Mpa for 150min to obtain a tin selenide ingot;

[0067] Step 2: crush the tin selenide ingot and sieve it to obtain a powder with a particle size of less than 3 mm;

[0068] Step 3: The powder was placed in a tubular atmosphere furnace, nitrogen was continuously introduced at a flow rate of 5 L / min for protection, and then the temperature was raised to 500° C. and kept for 4 h to obtain 1946 g of tin selenide powder.

[0069] Comparative Example 4

[0070] A high-purity tin selenide is prepared by the following steps:

[0071] Step 11: Put the selenium block and the tin block in a graphite crucible in a molar ratio of 1.1:1, weigh the selenium block to get 869g and the tin block to get 1187g, then put it in a high temperature and high pressure furnace and evacuate to <5*10 -4 Pa, introduce nitrogen to a pressure of 2MPa;

[0072] Step 12: heating to 400°C at a heating rate of 15°C / min and heat preservation for 50 minutes;

[0073] Step 13: Continue to increase the temperature at a heating rate of 5° C. / min and introduce nitrogen, and perform heat and pressure treatment at a temperature of 950° C. and a pressure of 5 MPa for 150 min to obtain a tin selenide ingot;

[0074] Step 2: crush the tin selenide ingot and sieve it to obtain a powder with a particle size of less than 3 mm;

[0075] Step 3: The powder was placed in a tubular atmosphere furnace, nitrogen was continuously introduced at a flow rate of 5 L / min for protection, and then the temperature was raised to 350° C. and kept for 4 h to obtain 1975 g of tin selenide powder.

[0076] Comparative Example 5

[0077] A high-purity tin selenide is prepared by the following steps:

[0078] Step 11: Put the selenium block and the tin block in a graphite crucible in a molar ratio of 1.1:1, weigh the selenium block to get 869g and the tin block to get 1187g, then put it in a high temperature and high pressure furnace and evacuate to <5*10 -4 Pa, introduce nitrogen to a pressure of 2MPa;

[0079] Step 12: heating to 400°C at a heating rate of 15°C / min and heat preservation for 50 minutes;

[0080] Step 13: Continue to increase the temperature at a heating rate of 5° C. / min and introduce nitrogen, and perform heat and pressure treatment at a temperature of 950° C. and a pressure of 5 MPa for 150 min to obtain a tin selenide ingot;

[0081] Step 2: crush the tin selenide ingot and sieve it to obtain a powder with a particle size of less than 3 mm;

[0082] Step 3: The powder was placed in a tubular atmosphere furnace, nitrogen was continuously introduced at a flow rate of 5 L / min for protection, and then the temperature was raised to 500° C. and kept for 2 h to obtain 1974 g of tin selenide powder.

[0083] Data Detection

[0084] Detection method:

[0085] 1. Tin selenide yield

[0086] The yield of tin selenide is calculated according to the following formula:

[0087]

[0088] 2. Tin selenide impurity content

[0089] The contents of free selenium and free tin were detected by DSC.

[0090] The tin selenide powders obtained in Examples 1-3 and Comparative Examples 1-5 were calculated and tested according to the above method, and the results are shown in Table 1;

[0091] Table 1 Data table of tin selenide powder yield and impurity content obtained in Examples 1-3 and Comparative Examples 1-5

[0092] Tin selenide yield% Free selenium content ppm Free tin content ppm Example 1 96.06％ ＜200 ＜200 Example 2 97.87％ ＜200 ＜200 Example 3 97.92％ ＜200 ＜200 Comparative Example 1 99.71％ 2500 ＜200 Comparative Example 2 99.16％ ＜200 3020 Comparative Example 3 94.65％ ＜200 13200 Comparative Example 4 96.06％ 2280 ＜200 Comparative Example 5 96.01％ 1840 ＜200

[0093] According to the data in Table 1:

[0094] According to the data of Examples 1-3, the present invention uses excess selenium to prepare tin selenide with tin to ensure the yield of tin selenide. At the same time, the synthesized tin selenide powder is subjected to a heat preservation treatment at 400-500° C. in step 3, which can effectively solve the problem of free selenium remaining in the tin selenide powder, thereby improving the purity of the tin selenide powder.

[0095] According to the data comparison between Example 1 and Comparative Example 1, when step 3 for treating free selenium is missing, the quality of the tin selenide powder decreases due to the high content of free selenium in the tin selenide powder, and the yield appears to be very high, but in fact it is basically caused by free selenium.

[0096] According to the data comparison between Example 1 and Comparative Example 2, if excess selenium is not used to prepare tin selenide, the direct synthesis method will lead to volatilization of selenium, resulting in an excessively high content of free tin and a significant decrease in the purity of tin selenide.

[0097] According to the data comparison of Example 1 and Comparative Example 3, if the temperature of the direct synthesis method is not suitable, the reaction will be incomplete, resulting in a decrease in the yield of tin selenide. At the same time, if the content of free selenium is too high, the yield and purity of tin selenide will be greatly reduced.

[0098] According to the data comparison between Example 1 and Comparative Examples 4 and 5, if the insulation temperature in step 3 is too low or the insulation time is too short, the free selenium will not be removed successfully, a large amount of free selenium will still exist in the tin selenide powder, and the purity of the tin selenide will decrease.

[0099] The embodiments presented herein are only embodiments selected according to the combination of all possible embodiments. The appended claims should not be limited by the embodiments describing the present invention. Some numerical ranges used in the claims include sub-ranges therein, and the changes in these ranges should also be covered by the appended claims.

Claims

1. A method for preparing high-purity tin selenide, characterized in that: The steps include: Step 1: In an inert gas atmosphere, a selenium element and a tin element are subjected to a temperature-raising reaction to synthesize a tin selenide ingot; Step 2: crushing the tin selenide ingot into powder; Step 3: heating the powder to 400-500° C. under inert gas protection and keeping the temperature for 4-5 hours to obtain tin selenide powder; The molar ratio of the selenium element to the tin element is 1.05-1.1:

1.

2. The method for preparing high-purity tin selenide according to claim 1, characterized in that: The specific operations of step 1 are: Step 11: Place the selenium block and the tin block into a graphite crucible, and then place it into a high-temperature and high-pressure furnace and evacuate to <5*10 -4 Pa, introduce inert gas to a pressure of 1-2MPa; Step 12: Raise the temperature to 300-400°C and keep warm for 30-60 minutes; Step 13: Continue to increase the temperature and introduce inert gas, and perform heat and pressure treatment at a temperature of 900-950° C. and a pressure of 4-5 MPa for 150-180 minutes to obtain a tin selenide ingot.

3. The method for preparing high-purity tin selenide according to claim 2, characterized in that: The heating rate of step 12 is 10-15°C / min.

4. The method for preparing high-purity tin selenide according to claim 2, characterized in that: The heating rate of step 13 is 5-10°C / min.

5. The method for preparing high-purity tin selenide according to claim 1, characterized in that: The powder particle size obtained in step 2 is less than 3 mm.

6. The method for preparing high-purity tin selenide according to claim 1, characterized in that: The specific operation of step 3 is: putting the powder into a tubular atmosphere furnace, continuously introducing inert gas protection at a flow rate of 3-5 L / min, and then heating to 400-500° C. and keeping the temperature for 4-5 hours to obtain tin selenide powder.

7. A high-purity tin selenide, characterized in that: The high-purity tin selenide is prepared by the preparation method of any one of claims 1 to 6.

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