Synthesis method of selenium and sulfide infrared optical crystal
The dual-zone tube furnace synthesis with double-walled crucibles and controlled temperature oscillation effectively addresses the issues of crucible explosion and chemical composition deviation in selenium sulfide nonlinear optical crystal synthesis, resulting in high-purity multi-crystalline materials.
Patent Information
- Application Number
- CN202510491889.6
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-04-18
- Publication Date
- 2025-07-15
AI Technical Summary
When synthesizing selenium and sulfide infrared optical crystals in the prior art, the crucible is prone to cracking or explosion due to high temperature vapor pressure, and the stoichiometric ratio deviates, poor quality of polycrystalline materials and low purity.
The structure of the double-layer quartz crucible is adopted. The inner quartz crucible is filled with elemental raw materials, and the outer quartz crucible provides auxiliary pressurization. Combined with the dual-temperature zone tube furnace and mechanical oscillation, the stoichiometric ratio is optimized through temperature oscillation, the high-temperature vapor pressure is reduced, and the purity and quality of the polycrystalline material are improved.
It effectively avoids crucible cracking or explosion, ensures the stoichiometric accuracy and purity of the polycrystalline material, improves the quality of the polycrystalline material, and is suitable for the synthesis of high-purity single-phase large-dose selenium and sulfide infrared optical crystals.
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Figure CN120311295A_ABST
Abstract
Description
Technical Field
[0001] The present invention belongs to the technical field of optoelectronic functional materials, relates to non-linear optical crystals, and particularly relates to a method for synthesizing selenium and sulfide infrared optical crystals. Background Art
[0002] Selenium and sulfide semiconductor non-linear optical crystals have important applications in the mid-infrared and far-infrared bands. With the in-depth research, two series of crystals, AgGaC2 (C = S, Se) and LiBC2 (B = Ga, In, C = S, Se), have been studied successively at home and abroad. The latter has the advantages of a wider band gap, higher thermal conductivity, larger laser damage threshold, and lower two-photon absorption due to the replacement of silver with lithium, and has important application value in laser frequency conversion.
[0003] However, since selenium and sulfide semiconductor non-linear optical crystals contain selenium and sulfur components, at high temperatures, these components are prone to generate very high vapor pressures, causing stoichiometric deviation and crucible explosion, resulting in experimental failure. Among them, polycrystalline synthesis is one of the most critical links, and the quality of the polycrystalline material is the key factor determining whether high-quality single crystals can be obtained. The high-temperature vapor pressure causes the crucible to crack or even explode, which is the main reason for experimental failure. At the same time, the too-high high-temperature selenium and sulfur vapor pressures are prone to cause stoichiometric deviation of the polycrystalline material and reduce the quality of the polycrystalline raw material.
[0004] Traditional polycrystalline synthesis methods are the single-temperature zone method and the two-temperature zone vapor transport method. In the single-temperature zone method for synthesizing polycrystals, due to the rapid increase in selenium and sulfur vapor pressures, the crucible is extremely prone to explosion, and the single synthesis amount is small. Although the two-temperature zone vapor transport method solves the explosion problem, there are still some difficulties: (1) During the synthesis of polycrystals using this method, the crucible is prone to cracking due to high vapor pressure; (2) The reaction between raw materials is not sufficient, resulting in poor quality of the obtained polycrystals; (3) Selenium and sulfur are extremely prone to vapor transport and separation from the melt at high temperatures, resulting in serious stoichiometric deviation; (4) High-melting-point binary selenium and sulfides generated during polycrystalline synthesis are likely to exist in the polycrystalline material in the form of impurities, resulting in low purity of the polycrystalline material. Summary of the Invention
[0005] Aiming at the above deficiencies existing in the prior art, the purpose of the present invention is to provide a method for synthesizing selenium and sulfide infrared optical crystals, which can effectively avoid crucible cracking and explosion, and can effectively prevent stoichiometric deviation, and obtain a polycrystalline material with high purity.
[0006] The technical solution of the present invention is realized as follows:
[0007] A method for synthesizing selenium and sulfide infrared optical crystals specifically includes the following steps:
[0008] (1) Weigh the elemental raw materials of each element according to the stoichiometric ratio of selenium and sulfide infrared optical crystals, and additionally weigh 2% - 5% of elemental selenium or elemental sulfur in molar ratio, and then load each elemental raw material into a quartz crucible;
[0009] (2) Evacuate the quartz crucible containing the elemental raw materials, and then seal it using a hydrogen-oxygen flame;
[0010] (3) Place the sealed quartz crucible into another quartz crucible, then evacuate it, and then seal it using a hydrogen-oxygen flame;
[0011] (4) Place the double-layer quartz crucible into a two-temperature-zone tubular furnace, and then heat the high-temperature zone and low-temperature zone of the two-temperature-zone tubular furnace respectively. When the low-temperature zone is heated to the reaction temperature at a gradient, hold for 5 - 10 h; then mechanically oscillate the two-temperature-zone tubular furnace 3 - 5 times to make the melt mix evenly, and then hold for another 5 - 10 h;
[0012] (5) After the reaction is completed, perform temperature oscillation 2 - 3 times;
[0013] (6) After the temperature oscillation is completed, the two-temperature-zone tubular furnace is cooled to room temperature, thereby obtaining the selenium and sulfide infrared optical crystal.
[0014] Further, in step (2), evacuate to (1 - 3)×10 -5 Pa.
[0015] Further, in step (3), evacuate to (2 - 5)×10 -2 Pa.
[0016] Further, when the selenide infrared optical crystal is AgGaSe2 polycrystalline material, the gradient heating step in step (4) is as follows: the high-temperature zone is heated to 210℃ - 230℃ at a heating rate of 5℃ - 10℃ / min, hold for 4 h - 10 h, then heated to 675 - 685℃ at a heating rate of 5℃ - 10℃ / min, hold for 4 h - 10 h, then heated to 950℃ - 980℃ at a heating rate of 5℃ - 10℃ / min, and then hold; meanwhile, the low-temperature zone is heated to 180℃ - 200℃ at a heating rate of 5℃ - 10℃ / min, hold for 5 - 10 h, then heated to 675 - 685℃ at a heating rate of 5℃ - 10℃ / min, hold for 2 - 4 h, then heated to 950℃ - 980℃ at a heating rate of 5℃ - 10℃ / min, hold for 5 - 10 h, then mechanically oscillate the two-temperature-zone tubular furnace 3 - 5 times to make the melt mix evenly; then hold for 5 - 10 h.
[0017] Further, in step (5), during temperature oscillation, the high-temperature zone and the low-temperature zone first cool from 950°C to 980°C to 880 - 930°C at a rate of 5 - 10°C / min, then cool from 880 - 930°C to 780 - 820°C at a rate of 5 - 10°C / min, and then heat from 780 - 820°C to 880 - 930°C at a rate of 5 - 10°C / min, and the temperature is raised and lowered 2 - 3 times for temperature oscillation.
[0018] Further, when the selenide infrared optical crystal is AgGaS2 polycrystalline material, the gradient heating step in step (4) is as follows: the high-temperature zone is heated to 100 - 120°C at a heating rate of 5 - 10°C / min, held for 4 - 8 h, then heated to 430 - 460°C at a heating rate of 5 - 10°C / min, held for 4 - 8 h, and then heated to 1000°C - 1100°C at a heating rate of 5 - 10°C / min, and then held; meanwhile, the low-temperature zone is heated to 100 - 120°C at a heating rate of 5 - 10°C / min, held for 8 - 12 h, then heated to 430 - 460°C at a heating rate of 5 - 10°C / min, held for 2 - 6 h, and then heated to 1000°C - 1100°C at a heating rate of 5 - 10°C / min, held for 5 - 10 h, and then the double-temperature zone tube furnace is mechanically oscillated 3 - 5 times to make the melt mix evenly; then held for 5 - 10 h.
[0019] Further, in step (5), during temperature oscillation, the high-temperature zone and the low-temperature zone first cool from 1000°C - 1100°C to 920°C - 950°C at a rate of 5 - 10°C / min, then cool from 920°C - 950°C to 1000°C - 1100°C at a rate of 5 - 10°C / min, and the temperature is raised and lowered 2 - 3 times for temperature oscillation.
[0020] Further, when the selenide infrared optical crystal is LiGa 0.3 In 0.7 When Se2 polycrystalline material, the gradient heating step in step (4) is as follows: the high-temperature zone is heated to 200 - 240°C at a heating rate of 5 - 10°C / min, held for 4 - 8 h, then heated to 660 - 700°C at a heating rate of 5 - 10°C / min, held for 4 - 8 h, and then heated to 950 - 1050°C at a heating rate of 5 - 10°C / min, and then held; meanwhile, the low-temperature zone is heated to 180 - 220°C at a heating rate of 5 - 10°C / min, held for 8 - 10 h, then heated to 660 - 700°C at a heating rate of 5 - 10°C / min, held for 2 - 4 h, and then heated to 950 - 1050°C at a heating rate of 5 - 10°C / min, held for 5 - 10 h, and then the double-temperature zone tube furnace is mechanically oscillated 3 - 5 times to make the melt mix evenly; then held for 5 - 10 h.
[0021] Furthermore, in step (5), during the temperature oscillation, the high temperature zone and the low temperature zone are first cooled from 950-1050°C to 880-930°C at a rate of 5-10°C / min, then cooled from 880-930°C to 780-830°C at a rate of 5-10°C / min, and then heated from 780-830°C to 880-930°C at a rate of 5-10°C / min, and the temperature is raised and lowered 2-3 times to perform temperature oscillation.
[0022] Furthermore, in step (1), if the selenium or sulfide infrared optical crystal contains lithium, the single element raw material is first placed in a graphite crucible, and then the graphite crucible is placed in a quartz crucible.
[0023] Compared with the prior art, the present invention has the following beneficial effects:
[0024] 1. The present invention places the single-element raw material into an inner quartz crucible, and places the inner quartz crucible into an outer quartz crucible with pressure resistance, and evacuates the inner quartz crucible and the outer quartz crucible respectively, and the inner quartz crucible is highly vacuumed ((1-3)×10 -5 Pa) in order to prevent the residual air from reacting with the high-purity single-element raw materials to produce impurities, the outer quartz crucible is evacuated to (2-5) × 10 -2 Pa, so that there is a small amount of air in the outer quartz crucible. In this way, under high temperature conditions, Se or S volatilizes and the pressure in the inner quartz crucible rises rapidly. The small amount of air in the outer quartz crucible causes a slight increase in pressure due to thermal movement under high temperature conditions, and also produces a certain vapor pressure. That is, the outer pressure-bearing quartz crucible produces external pressurization assistance, which can effectively improve the pressure resistance of the inner quartz crucible, thereby effectively preventing the inner quartz crucible from cracking or exploding due to the excessive pressure of the inner high-temperature steam.
[0025] At the same time, research has shown that: if the outer quartz crucible has a high vacuum degree and contains very little air, as the temperature rises, the vapor pressure caused by the temperature of this layer is very small, and it cannot play an auxiliary pressurization effect, which can easily cause the inner quartz crucible to be subjected to a larger inner vapor pressure and crack or explode; if the outer quartz crucible has a low vacuum degree and contains more air, at high temperatures, the pressure inside the outer quartz crucible is too high, which can easily cause the inner quartz crucible to be subjected to a larger air pressure and crack or explode.
[0026] 2. When the temperature reaches the highest reaction temperature, the dual-temperature zone tubular furnace is mechanically oscillated. Through the oscillation, the S, Se elements, metal single substances and binary compounds in the crucible react more fully, which effectively reduces the high-temperature vapor pressure in the inner reaction crucible on the one hand, and obtains high-quality polycrystalline materials on the other hand.
[0027] 3. After the completion of the highest temperature reaction stage, the present invention starts to cool down. When the temperature drops to near the melting point of the polycrystal, temperature oscillation begins. The temperature decreases from about 50 °C above the melting point to 50 °C below the melting point, and then rises to 50 °C above the melting point. The temperature rise and fall cycle is repeated 3 times. Through temperature oscillation, the reactants change from the molten state to the solid state and then from the solid state to the molten state. During the phase transition process, temperature oscillation can promote the transport of free S and Se vapors into the melt, reduce the volatilization of S and Se elements from the melt, and continuously optimize the stoichiometric ratio, thereby further ensuring the purity of the polycrystalline material. BRIEF DESCRIPTION OF THE DRAWINGS
[0028] Figure 1 - Schematic structural diagram of the synthesis equipment adopted by the present invention.
[0029] Figure 2 - Photograph of the AgGaSe2 polycrystalline material synthesized in Example 1.
[0030] Figure 3 - Powder XRD pattern of the AgGaSe2 polycrystalline material synthesized in Example 1.
[0031] Figure 4 - Photograph of the AgGaS2 polycrystalline material synthesized in Example 2.
[0032] Figure 5 - Powder XRD pattern of the AgGaS2 polycrystalline material synthesized in Example 2.
[0033] Figure 6 - LiGa synthesized in Example 3 0.3 In 0.7 Photograph of the Se2 polycrystalline material.
[0034] Figure 7 - LiGa synthesized in Example 3 0.3 In 0.7 Powder XRD pattern of the Se2 polycrystalline material.
[0035] Wherein: 1 is the base; 2 is the double-temperature zone tubular furnace; 3 is the hydraulic rod; 4 is the outer quartz crucible; 5 is the inner quartz crucible. DETAILED DESCRIPTION OF THE EMBODIMENTS
[0036] As Figure 1As shown, a horizontal furnace device for high temperature and high pressure synthesis of selenium and sulfide infrared optical crystals includes a base 1 and a double temperature zone tubular furnace 2. The double temperature zone tubular furnace 2 is arranged on the base 1 by hydraulic rods 3 arranged at both ends of the double temperature zone tubular furnace 2. The inclination angle of the furnace body is adjusted by lifting and lowering the electric hydraulic rods at both ends. The inclination angle of the furnace body to the ground is in the range of -60-+60°. In the high temperature melting stage of the raw material synthesis process, the furnace body is tilted and shaken by lifting and lowering the hydraulic rods to perform mechanical oscillation, so that the products in the high temperature stage can be fully mixed and reacted.
[0037] The dual-temperature zone tubular furnace is a two-stage tubular furnace. By adopting two-stage heating, a uniform and controllable temperature field can be obtained. A thermocouple protected by a corundum tube is placed in the middle of the heating section, which can more accurately reflect the actual temperature in the pressure container. A double-layer quartz crucible is placed inside the tubular furnace. When the double-layer quartz crucible is used, the raw materials are loaded into the inner quartz crucible 5, and then the inner quartz crucible 5 is evacuated to a high vacuum and sealed with a hydrogen-oxygen flame. Finally, the inner quartz crucible 5 is placed on the outer quartz crucible 4 and sealed with a hydrogen-oxygen flame. The sealed double-layer quartz crucible is placed in a double-temperature zone tubular furnace, and then the two heating zones of the double-temperature zone tubular furnace are heated according to the corresponding heating curve of the raw materials. When the temperature rises to the high-temperature reaction stage, the furnace body is lifted and shaken several times by the extension and contraction of the hydraulic rod to make the melt evenly mixed and fully reacted. After the high-temperature reaction is completed, the temperature begins to drop, and the temperature is repeatedly above and below the melting point for several times to perform temperature oscillation to optimize the stoichiometric ratio. After the temperature oscillation, it drops to room temperature, and then the quartz crucible is taken out to obtain the synthetic product.
[0038] On the basis of verifying the ability of the quartz crucible to withstand internal and external pressures, the present invention places the reaction crucible in another quartz crucible. When the temperature rises, there is a certain pressure in the outer quartz crucible, that is, the external auxiliary pressure is increased, so as to achieve the purpose of improving the resistance of the quartz crucible to internal pressure; compared with the single temperature zone method and the single-layer quartz tube, the double-layer quartz crucible, the double-temperature zone gas phase transport method, combined with high-temperature mechanical oscillation and temperature oscillation, can shorten the synthesis time, improve the synthesis success rate, improve the crystal quality, and can be used for the polycrystalline synthesis of high-purity single-phase large-dose sulfur and selenide infrared optical crystals. By installing a hydraulic rod between the double-temperature zone tubular furnace and the base, in the stage of raw material synthesis melting and mutual reaction, the raw materials in the crucible can be better contacted with each other by adjusting the inclination angle of the furnace body, so that the chemical reaction of the raw materials is more sufficient; when the mechanical oscillation ends and the temperature starts to drop, the temperature is adjusted to oscillate 50°C above and below the melting point, and the stoichiometric ratio is continuously optimized to achieve the purpose of improving the quality of polycrystalline.
[0039] At the same time, if the selenium and sulfide infrared optical crystals contain lithium elements, during synthesis, the single-element raw materials must first be placed in a graphite crucible, and then the graphite crucible is placed in an inner quartz crucible to avoid reaction between lithium and the crucible material.
[0040] The present invention will be further described in detail below in conjunction with the accompanying drawings and specific embodiments.
[0041] Example 1
[0042] The synthesis steps of AgGaSe2 polycrystalline material are as follows:
[0043] (1) Weigh a total of 50 grams of high-purity Ag, Ga, and Se in a molar ratio of 1:1:2, and weigh an additional 3% of Se in terms of molar ratio. Put the weighed elemental substances into a quartz crucible with a carbon film plated on the inner wall. The size of the quartz crucible is 22 mm in inner diameter, 3 mm in wall thickness, and 300 mm in length.
[0044] (2) After evacuating the quartz crucible containing the elemental raw materials to 2×10 -5 Pa by a vacuum molecular pump, seal it with a hydrogen-oxygen flame.
[0045] (3) Put the sealed quartz crucible into another quartz crucible. The size of the outer quartz crucible is 28 mm in inner diameter, 3 mm in thickness, and 400 mm in length. After evacuating it to 2×10 -2 Pa by a vacuum molecular pump, seal it with a hydrogen-oxygen flame.
[0046] (3) Put the double-layer quartz crucible into a two-temperature-zone tube furnace. Then heat the high-temperature zone of the two-temperature-zone tube furnace to 220 °C at a heating rate of 10 °C / min, keep it at a constant temperature of 220 °C for a total of 4 h, and then heat it to 685 °C at a heating rate of 5 °C / min, and keep it at a constant temperature of 685 °C for a total of 4 h; then heat it to 950 °C at a heating rate of 5 °C / min and keep it at a constant temperature.
[0047] At the same time, heat the low-temperature zone of the two-temperature-zone tube furnace to 200 °C at a heating rate of 10 °C / min and keep it at a constant temperature for 8 h. Then heat it to 685 °C at a heating rate of 5 °C / min. After keeping it warm for 2 h, raise the temperature to 950 °C at the same heating rate and keep it warm.
[0048] After the temperatures of the high-temperature zone and the low-temperature zone of the two-temperature-zone tube furnace reach 950 °C and are kept warm for 5 h, adjust the angle of the furnace body 3 times up and down by a hydraulic rod to make the melt uniform and the reaction sufficient, and then keep it warm for another 5 h.
[0049] (4) After the reaction is completed, start temperature oscillation. Cool from 950 °C to 900 °C at a rate of 10 °C / min, cool from 900 °C to 800 °C at a rate of 5 °C / min, and then raise the temperature from 800 °C to 900 °C at a rate of 5 °C / min. Repeat the temperature rise and fall 3 times for oscillation to further optimize the stoichiometric ratio. Finally, cool the two-temperature-zone tube furnace to room temperature at a rate of 20 °C / min, take out the double-layer quartz crucible, and take out the synthesized product.
[0050] The photo of the synthesized polycrystalline material in this example is asFigure 2 As shown, it can be seen from the figure that the synthesized product is black - gray, with a complete appearance, no cracks or adhesions, and surface reflection, indicating that the obtained product is polycrystalline and the composition is relatively uniform. It shows that the use of a double - layer quartz crucible and a two - temperature - zone vapor transport method combining mechanical oscillation and temperature oscillation can successfully synthesize high - quality polycrystals. The powder XRD pattern of the synthesized polycrystalline material is as Figure 3 shown. There are no impurity peaks in the powder XRD. The experimental results are in good agreement with the PDF card JCPDS:31 - 1204. This polycrystalline material is a high - purity single - phase AgGaSe2 compound, and the polycrystalline purity is higher than 99%, which can be used as the raw material for single - crystal growth.
[0051] Example 2
[0052] The synthesis steps of the AgGaS2 polycrystalline material are as follows:
[0053] (1) Weigh a total of 50 grams of high - purity Ag, Ga, and S in a mass ratio of 1:1:2, and weigh an additional 3% molar ratio of S. Then put the weighed elements into a quartz crucible with a carbon - coated inner wall. The size of the quartz crucible is 22 mm in inner diameter, 3 mm in wall thickness, and 300 mm in length.
[0054] (2) After evacuating the quartz crucible containing the elemental raw materials to 2×10 -5 Pa by a vacuum molecular pump, seal it with a hydrogen - oxygen flame.
[0055] (3) Put the sealed quartz crucible into another quartz crucible. The size of the outer - layer quartz crucible is 28 mm in inner diameter, 3 mm in thickness, and 400 mm in length. After evacuating it to 2×10 -2 Pa by a vacuum molecular pump, seal it with a hydrogen - oxygen flame.
[0056] (3) Put the double - layer quartz crucible into a two - temperature - zone tube furnace. Then heat the high - temperature zone of the two - temperature - zone tube furnace to 113℃ at a heating rate of 10℃ / min and keep it at a constant temperature of 113℃ for 4 h; heat it to 445℃ at a heating rate of 5℃ / min and keep it at a constant temperature of 445℃ for 4 h; then heat it to 1050℃ at a heating rate of 5℃ / min and keep it at a constant temperature of...
[0057] At the same time, heat the low - temperature zone of the two - temperature - zone tube furnace to 100℃ at a heating rate of 10℃ / min and keep it at a constant temperature of 8 h; then heat it to 445℃ at a heating rate of 5℃ / min, keep it warm for 2 h, and then raise the temperature to 1050℃ at the same heating rate and keep it warm.
[0058] After the temperatures of the high - temperature zone and the low - temperature zone of the two - temperature - zone tube furnace reach 1050℃ and are kept at a constant temperature for 5 h, adjust the angle of the furnace body 3 times up and down by a hydraulic rod to make the melt uniform and the reaction sufficient, and then keep it at a constant temperature for another 5 h.
[0059] (4) After the reaction is completed, temperature oscillation is started. The temperature is decreased from 1050 °C to 950 °C at a rate of 5 °C / min, and then increased from 950 °C to 1050 °C at a rate of 5 °C / min. The temperature is raised and lowered 3 times for oscillation to further optimize the stoichiometric ratio. Finally, the two-zone tube furnace is cooled to room temperature at a rate of 20 °C / min, the double-layer quartz crucible is taken out, and the synthesized product is taken out.
[0060] The photograph of the synthesized polycrystalline material in this example is as Figure 4 shown. As can be seen from the figure, the synthesized product is yellow, with a complete appearance, no cracks or adhesions, and a certain amount of light reflection on the surface, indicating that the obtained product is polycrystalline and the composition is relatively uniform. It shows that the double-layer quartz crucible and the two-zone gas-phase transport method combined with mechanical oscillation and temperature oscillation can successfully synthesize high-quality polycrystals; the powder XRD pattern of the synthesized polycrystalline material is as Figure 5 shown. There are no impurity peaks in the powder XRD. The experimental results are in good agreement with the PDF card JCPDS: 27-0615. This polycrystalline material is a high-purity single-phase AgGaS2 compound, and the polycrystalline purity is higher than 99%, which can be used as a raw material for single crystal growth.
[0061] Example 3
[0062] LiGa 0.3 In 0.7 The synthesis steps of Se2 polycrystalline material are as follows:
[0063] (1) Weigh 50 grams of high-purity Ag, Ga, In, and S in a mass ratio of 1:0.3:0.7:2, and weigh an additional 3% of Se in molar ratio. Put the weighed elements into a graphite crucible with an inner diameter of 16 mm, a wall thickness of 3 mm, and a length of 250 mm. Then put the graphite crucible into a quartz crucible with an inner diameter of 22 mm, a wall thickness of 3 mm, and a length of 300 mm.
[0064] (2) After evacuating the above quartz crucible to 2×10 -5 Pa by a vacuum molecular pump, seal it with a hydrogen-oxygen flame.
[0065] (3) Put the sealed quartz crucible into another quartz crucible with an outer layer quartz crucible having an inner diameter of 28 mm, a thickness of 3 mm, and a length of 400 mm. Evacuate it to 2×10 -2 Pa by a vacuum molecular pump, and seal it with a hydrogen-oxygen flame.
[0066] (4) Put the double-layer quartz crucible into the two-zone tube furnace. Then heat the high-temperature zone of the two-zone tube furnace to 220 °C at a heating rate of 10 °C / min and keep it at 220 °C for 4 h; then heat it to 685 °C at a heating rate of 5 °C / min and keep it at 685 °C for 4 h; then heat it to 970 °C at a heating rate of 5 °C / min and keep it at a constant temperature.
[0067] Meanwhile, heat the low-temperature zone of the two-temperature-zone tube furnace to 200 °C at a heating rate of 10 °C / min and keep it at a constant temperature for 8 h; then heat it to 685 °C at a heating rate of 5 °C / min, keep it for 2 h, and then heat it to 970 °C at the same heating rate and keep it at a constant temperature.
[0068] After the temperatures of both the high-temperature zone and the low-temperature zone of the two-temperature-zone tube furnace reach 970 °C and are kept at a constant temperature for 5 h, adjust the furnace body angle by the hydraulic rod to perform 3 times of lifting and shaking, so that the melt is uniform and the reaction is sufficient, and then keep it at a constant temperature for another 5 h.
[0069] (5) After the reaction is completed, start temperature oscillation. Cool from 970 °C to 900 °C at 10 °C / min, cool from 900 °C to 800 °C at 5 °C / min, and then heat from 800 °C to 900 °C at 5 °C / min. Reciprocate the temperature for 3 times of lifting and lowering for oscillation to further optimize the stoichiometric ratio. Finally, cool the two-temperature-zone furnace to room temperature at a rate of 20 °C / min, take out the double-layer quartz crucible, and take out the synthesized product.
[0070] The photo of the polycrystalline material synthesized in this example is as Figure 6 shown. As can be seen from the figure, the synthesized product is brownish-red, with a complete appearance, no cracks and no adhesion, and has a certain reflectivity on the surface, indicating that the obtained product is polycrystalline and the composition is relatively uniform, indicating that the double-layer crucible and the two-temperature-zone gas-phase transport method combining mechanical oscillation and temperature oscillation can successfully synthesize high-quality polycrystals; the powder XRD pattern of the synthesized polycrystalline material is as Figure 7 shown. There are no impurity peaks in the powder XRD. This polycrystalline material is a high-purity single-phase LiGa 0.3 In 0.7 Se2 compound, and the polycrystalline purity is higher than 99%, which can be used as the raw material for single crystal growth.
[0071] Finally, it should be noted that the above embodiments of the present invention are only examples for explaining the present invention, and are not limitations on the implementation modes of the present invention. For those of ordinary skill in the art, other different forms of changes and modifications can be made on the basis of the above description. It is impossible to list all the implementation modes here. Any obvious changes or modifications derived from the technical solutions of the present invention still fall within the protection scope of the present invention.
Claims
1. A method for synthesizing selenium and sulfide infrared optical crystals, characterized in that, Specifically, it includes the following steps: (1) Weigh the elemental raw materials of each element according to the stoichiometric ratio of the selenium and sulfide infrared optical crystal, and additionally weigh 2% - 5% of elemental selenium or elemental sulfur in terms of molar ratio, and then load each elemental raw material into a quartz crucible; (2) Vacuum the quartz crucible containing the elemental raw materials, and then seal it with a hydrogen-oxygen flame; (3) Place the above-sealed quartz crucible into another quartz crucible, then vacuum it, and then seal it with a hydrogen-oxygen flame; (4) Place the double-layer quartz crucible into a two-temperature-zone tubular furnace, and then heat the high-temperature zone and the low-temperature zone of the two-temperature-zone tubular furnace respectively. When the low-temperature zone is heated to the reaction temperature at a gradient, keep it warm for 5 - 10 h; then mechanically oscillate the two-temperature-zone tubular furnace 3 - 5 times to make the melt mix evenly, and then keep it warm for another 5 - 10 h; (5) After the reaction ends, perform temperature oscillation 2 - 3 times; (6) After the temperature oscillation ends, the two-temperature-zone tubular furnace is cooled to room temperature, thereby obtaining the selenium and sulfide infrared optical crystal.
2. The synthesis method of a selenium and sulfide infrared optical crystal according to claim 1, wherein, In step (2), evacuate to (1 - 3)×10 -5 Pa.
3. A method for synthesizing a selenium and sulfide infrared optical crystal according to claim 1 or 2, characterized in that, In step (3), evacuate to (2 - 5)×10 -2 Pa.
4. A method for synthesizing a selenium and sulfide infrared optical crystal according to claim 1, characterized in that, When the selenide infrared optical crystal is AgGaSe2 polycrystalline material, the gradient heating step in step (4) is: the high-temperature zone is heated to 210°C - 230°C at a heating rate of 5°C - 10°C / min, keep it warm for 4 h - 10 h, then heated to 675 - 685°C at a heating rate of 5°C - 10°C / min, keep it warm for 4 h - 10 h, and then heated to 950°C - 980°C at a heating rate of 5°C - 10°C / min, and then keep it warm; meanwhile, the low-temperature zone is heated to 180°C - 200°C at a heating rate of 5°C - 10°C / min, keep it warm for 5 - 10 h, then heated to 675 - 685°C at a heating rate of 5°C - 10°C / min, keep it warm for 2 - 4 h, and then heated to 950°C - 980°C at a heating rate of 5°C - 10°C / min, keep it warm for 5 - 10 h, and then mechanically oscillate the two-temperature-zone tubular furnace 3 - 5 times to make the melt mix evenly; and then keep it warm for 5 - 10 h.
5. A method for synthesizing a selenium and sulfide infrared optical crystal according to claim 4, characterized in that, In step (5), during the temperature oscillation, the high-temperature zone and the low-temperature zone first cool from 950°C - 980°C to 880 - 930°C at 5 - 10°C / min, then cool from 880 - 930°C to 780 - 820°C at 5 - 10°C / min, and then rise from 780 - 820°C to 880 - 930°C at 5 - 10°C / min, and reciprocate the temperature rise and fall 2 - 3 times for temperature oscillation.
6. The synthesis method of a selenium and sulfide infrared optical crystal according to claim 1, characterized in that, When the selenide infrared optical crystal is AgGaS2 polycrystalline material, the gradient heating step in step (4) is as follows: in the high-temperature zone, it is heated at a heating rate of 5-10 °C / min to 100-120 °C, kept warm for 4-8 h, then heated at a heating rate of 5-10 °C / min to 430-460 °C, kept warm for 4-8 h, and then heated at a heating rate of 5-10 °C / min to 1000 °C-1100 °C, and then kept warm; meanwhile, in the low-temperature zone, it is heated at a heating rate of 5-10 °C / min to 100-120 °C, kept warm for 8-12 h, then heated at a heating rate of 5-10 °C / min to 430-460 °C, kept warm for 2-6 h, and then heated at a heating rate of 5-10 °C / min to 1000 °C-1100 °C, kept warm for 5-10 h, and then the two-temperature-zone tube furnace is mechanically oscillated 3-5 times to make the melt mix evenly; then kept warm for 5-10 h.
7. The synthesis method of a selenium and sulfide infrared optical crystal according to claim 6, characterized in that, In step (5), during temperature oscillation, the high-temperature zone and the low-temperature zone first cool from 1000 °C-1100 °C to 920 °C-950 °C at a rate of 5-10 °C / min, and then cool from 920 °C-950 °C to 1000 °C-1100 °C at a rate of 5-10 °C / min, and the temperature is raised and lowered 2-3 times for temperature oscillation.
8. A method for synthesizing a selenium and sulfide infrared optical crystal according to claim 1, characterized in that, The selenide infrared optical crystal is LiGa 0.3 In 0.7 When it is Se2 polycrystalline material, the gradient heating step in step (4) is as follows: in the high-temperature zone, it is heated at a heating rate of 5-10 °C / min to 200-240 °C, held for 4-8 h, then heated at a heating rate of 5-10 °C / min to 660-700 °C, held for 4-8 h, then heated at a heating rate of 5-10 °C / min to 950-1050 °C, and then held; at the same time, in the low-temperature zone, it is heated at a heating rate of 5-10 °C / min to 180-220 °C, held for 8-10 h, then heated at a heating rate of 5-10 °C / min to 660-700 °C, held for 2-4 h, then heated at a heating rate of 5-10 °C / min to 950-1050 °C, held for 5-10 h, then the two-temperature zone tube furnace is mechanically oscillated 3-5 times to make the melt mix evenly; and then held for 5-10 h.
9. The synthesis method of a selenium and sulfide infrared optical crystal according to claim 8, characterized in that, In step (5), during temperature oscillation, the high-temperature zone and the low-temperature zone first cool from 950-1050 °C to 880-930 °C at a rate of 5-10 °C / min, then cool from 880-930 °C to 780-830 °C at a rate of 5-10 °C / min, and then rise from 780-830 °C to 880-930 °C at a rate of 5-10 °C / min, and the temperature is raised and lowered 2-3 times for temperature oscillation.
10. A method for synthesizing a selenium and sulfide infrared optical crystal according to claim 1, characterized in that, In step (1), if the selenium and sulfide infrared optical crystal contains lithium element, the elemental raw materials are first put into a graphite crucible, and then the graphite crucible is put into a quartz crucible.