Method for preparing indium lead telluride polycrystalline material for single crystal growth by horizontal gradient crystallization method

Abstract

A method for preparing indium lead telluride polycrystalline material for single crystal growth by horizontal gradient crystallization method, which relates to a method for preparing indium lead telluride polycrystalline material. It aims to solve the technical problems of severe cracking and strong optical absorption of existing PIT single crystals. This method: weigh Pb source, In source, Te source and In2Te3 raw materials and put them in a crucible, put Te that provides atmosphere pressure in another crucible, and then place the two crucibles at both ends of a quartz tube, fill them with inert gas and seal them; put the quartz tube in a double-temperature zone horizontal tube furnace, put the raw material crucible in the high temperature zone, and the other crucible in the low temperature zone, and obtain indium lead telluride polycrystalline material after the reaction stage, homogenization stage, gradient crystallization stage and cooling stage. Single crystals are grown using the polycrystalline material, and the optical absorption of a double-sided polished wafer with a thickness of 4.385 mm is less than 0.17 cm at 2.09 μm. ‑1 , can be used with the help of laser pumping to output mid-infrared and far-infrared lasers for use in industry, medicine and energy fields.

Description

Technical Field

[0001] The invention relates to a method for preparing indium lead telluride polycrystalline material. Background Art

[0002] Nonlinear optical crystals in the infrared band have broad application prospects in important fields such as industry, medicine and energy. However, the intrinsic defects of chalcopyrite crystals (such as AgGaS2, AgGaSe2 and ZnGeP2) used in commercial infrared bands, such as low laser damage threshold and two-photon absorption, limit their application in far-infrared high-power solid-state lasers. The development of modern infrared laser technology requires new crystals with the following properties: First, they can efficiently utilize the 1064nm laser pump output by Nd:YAG lasers. Second, the new crystals need to cover an output range of more than 10μm.

[0003] Compared with phosphorus compounds, telluride crystals in chalcogenides have lower phonon energy, which is conducive to obtaining nonlinear optical crystal materials with a transmission range covering the 10-14 μm atmospheric window. 10 (PIT) crystal is a new type of nonlinear optical material. It belongs to the trigonal system and crystallizes in the R32 space group. It has a light transmission band (1.3-31 μm), suitable birefringence (~0.05), and a large nonlinear coefficient (d 11 =51pm / V). In addition, 2μm laser can be used to output 5-25μm continuously tunable laser through optical parametric oscillation technology. Theoretical simulation also proves that PIT crystal has the ability to achieve 10-30μm laser output.

[0004] The PIT crystals grown by the current method suffer from severe crystal cracking, strong optical absorption, and uneven distribution of elements inside the crystal. The main reason for the above phenomena is that PIT crystals are a type of non-uniform molten compounds, and the melt composition is difficult to control during the single crystal growth process. Therefore, there is an urgent need for a method to prepare polycrystalline raw materials for high-quality PIT single crystal growth. Summary of the invention

[0005] The present invention aims to solve the technical problems of severe crystal cracking and strong optical absorption of existing PIT single crystals, thereby providing a method for synthesizing polycrystalline raw materials that are helpful for growing high-quality PIT single crystals by means of horizontal gradient crystallization. The method synthesizes PIT polycrystalline materials by means of gradient crystallization, and uses the polycrystalline raw materials to grow single crystals with low optical absorption, so that it meets the requirements of far-infrared laser output by 2.09μm laser pump optical parametric oscillation.

[0006] The method for preparing a PIT polycrystalline raw material for single crystal growth by a horizontal gradient crystallization method of the present invention is carried out according to the following steps:

[0007] 1. In an inert atmosphere glove box, weigh Pb source, In source and Te source according to the stoichiometric ratio of Pb:In:Te of 1:6:10, weigh additional In2Te3 according to 1% to 7% of the total mass of Pb source, In source and Te source, and weigh out Te to provide atmosphere pressure;

[0008] 2. Place the Pb source, In source, Te source and additional In2Te3 in one crucible, place Te that provides the atmosphere pressure in another crucible, and then place the two crucibles at both ends of a quartz tube, respectively, and fill the quartz tube with 0.1-0.99atm of inert gas, and then use a hydrogen-oxygen flame to melt and seal the quartz tube;

[0009] 3. Preparation of PIT polycrystalline materials by heating reaction:

[0010] (1) Reaction stage: The sealed quartz tube is placed in a dual-temperature zone horizontal tube furnace. The Pb source, In source, Te source and additional In2Te3 are placed in the high temperature zone, and Te that provides atmosphere pressure is placed in the low temperature zone. The Te in the low temperature zone is used to avoid the generation of binary impurities In2Te, InTe, and In3Te4 during the synthesis process, thereby affecting the purity of the product; the high temperature zone is heated to 350-450°C at a rate of 5-20°C / h and kept at a constant temperature for 3-10 hours. The purpose of this process is to control the reaction rate of the active metal Pb and Te element to avoid violent reactions that cause the final product of the compound to deviate from the stoichiometric ratio; then the temperature is continued to be raised to 700-800°C at a rate of 5-10°C / h and maintained for 50-100 hours. The purpose is to convert the high melting point In7Te 10 Completely melt to ensure that there is no In7Te in the product 10 Impurities; During this stage, the low temperature zone is heated to 500°C at a rate of 5-20°C / h and kept at 500°C throughout this stage; this temperature control can better avoid the formation of impurity products during the reaction process;

[0011] (2) Homogenization stage: After the reaction stage is completed, the temperature field in the low temperature zone is rapidly heated to 950-1000°C at a rate of 10-30°C / h, and the temperature field in the high temperature zone is kept at 700-800°C for 50-100h. The purpose of this stage is to promote the complete reaction of the binary and ternary tellurides formed in the crucible in the high temperature zone, and to make the pressure in the quartz tube in the low temperature zone greater than that in the high temperature zone, so as to avoid the decomposition of the compound under high temperature state and cause the segregation of the compound, which is conducive to the formation of a homogenized PIT single homogeneous compound.

[0012] (3) Gradient crystallization stage: The temperature in the low temperature zone is kept constant at 950-1000°C; the temperature field in the high temperature zone is rapidly changed at a rate of 20-50°C / h, forming a temperature field with a gradient of 1-5°C / cm in the high temperature zone, and gradient crystallization is performed at a rate of 0.1-10 mm / h;

[0013] (4) Cooling stage: The high temperature zone is cooled to room temperature at a rate of 15 to 30°C / h, and the low temperature zone is cooled to room temperature at a rate of 30 to 60°C / h to obtain the indium lead telluride polycrystalline material for single crystal growth.

[0014] Furthermore, the Pb source described in step 1 is bulk metallic lead, powdered metallic lead, beaded metallic lead or lead telluride compound.

[0015] Furthermore, the In source in step 1 is bulk metal element indium, powdered metal element indium, beaded metal element indium or indium tritelluride compound.

[0016] Furthermore, the Te source in step 1 is bulk single crystal tellurium, powdered metal tellurium or beaded metal tellurium.

[0017] Furthermore, the mass of Te for providing the atmosphere pressure in step 1 is 3 to 10 grams.

[0018] Furthermore, the crucible in step 2 is made of carbon-coated quartz, high-purity corundum, high-purity graphite or high-purity pyrolytic boron nitride.

[0019] Furthermore, the inert gas in step 2 is N2, Ar or He.

[0020] The indium lead telluride polycrystalline material for single crystal growth prepared by the present invention is placed in a mortar and crushed into a powder state, and then placed in a pyrolytic boron nitride crucible, and the crucible is placed in a quartz tube, and 0.1 to 6.0 g of Te single substance is additionally added to the quartz tube to provide a Te vapor atmosphere; and then a molecular pump is used to evacuate to 10 -5 Pa, using hydrogen-oxygen flame to melt and seal the quartz tube; placing the quartz tube in a horizontal Bridgman single crystal growth furnace, placing the powdered indium lead telluride polycrystalline material in a constant temperature zone 20 to 50°C higher than the melting point for 20 to 100 hours, and then growing the PIT single crystal under the conditions of a temperature gradient of 1 to 10°C / cm and a growth rate of 0.1 to 2.0 mm / h. After the growth is completed, the temperature is lowered to room temperature at a rate of 5 to 60°C / h to obtain the PIT single crystal.

[0021] The present invention adopts the horizontal gradient crystallization method to evenly disperse the additionally added In2Te3 compound to various parts of the polycrystalline ingot, and the purity of the area with better crystallinity is significantly improved, and the prepared PIT polycrystalline material suitable for the growth of PIT single crystals is prepared. The single crystal is grown by the horizontal Bridgman crucible descent method. The grown single crystal is cut into a PIT wafer with a thickness of 4.385 mm and double-sided polished. The optical absorption of the wafer at 2.09 μm is less than 0.17 cm -1 , which is conducive to pumping the output of mid- and far-infrared lasers with the help of 2.09μm lasers. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 Schematic diagram of the dual-temperature zone synthesis in Example 1; in the figure, 1 is the first crucible, 2 is the second crucible, 3 is the quartz tube, 4 is the high temperature zone, 5 is the low temperature zone, and 6 is the heating module;

[0023] Figure 2 It is the temperature curve diagram in step 3 in Example 1;

[0024] Figure 3 is a photograph of the indium lead telluride polycrystalline material obtained in Example 1;

[0025] Figure 4 is the XRD spectrum of the indium lead telluride polycrystalline material synthesized in Example 1;

[0026] Figure 5 The PIT single crystal wafer is cut from a single crystal grown from the indium lead telluride polycrystalline material synthesized in Example 1;

[0027] Figure 6 This is the absorption curve of the PIT single crystal in Example 1. DETAILED DESCRIPTION

[0028] The beneficial effects of the present invention are verified by the following examples.

[0029] Embodiment 1: The method for preparing PIT polycrystalline material for single crystal growth by horizontal gradient crystallization method of this embodiment is carried out according to the following steps:

[0030] 1. In an inert atmosphere glove box, weigh 28.617 g of powdered metal element lead, 95.149 g of powdered metal element indium, 176.233 g of powdered metal element tellurium according to the stoichiometric ratio of Pb:In:Te of 1:6:10, and weigh an additional 15 g of powdered In2Te3 and 5.00 g of Te to provide atmosphere pressure;

[0031] 2. In a glove box, powdered metal element lead, powdered metal element indium, powdered metal element tellurium and additional powdered In2Te3 are put into a mortar, mixed and ground evenly, and placed in a boat-shaped PBN first crucible 1, and Te providing atmosphere pressure is placed in another boat-shaped second PBN crucible 2, and then the two crucibles are placed at both ends of a quartz tube 3, and 0.5atm nitrogen is filled into the quartz tube at the same time, and then the quartz tube is melted and sealed using a hydrogen-oxygen flame;

[0032] 3. Preparation of PIT polycrystalline materials by heating reaction:

[0033] (1) Reaction stage: The sealed quartz tube is placed in a dual-temperature zone horizontal tube furnace, the mixed powder of Pb, In, Te and In2Te3 is placed in the high temperature zone 4, and Te providing the atmosphere pressure is placed in the low temperature zone 5; the high temperature zone is heated to 400°C at a rate of 15°C / h and kept at this temperature for 10 hours. The purpose of this process is to control the reaction rate of the active metal lead and the non-metallic tellurium element to avoid the violent reaction that causes the final product of the compound to deviate from the stoichiometric ratio; then the temperature is continued to be raised to 750°C at a rate of 8°C / h and maintained for 70 hours. The purpose is to convert the high melting point In7Te3 into 10 Completely melt to ensure that there is no In7Te in the product 10 Impurities; During this stage, the low temperature zone is heated to 500°C at a rate of 15°C / h and kept at 500°C throughout this stage; this temperature control can better suppress the intensity of chemical reactions;

[0034] (2) Homogenization stage: After the reaction stage is completed, the temperature field in the high temperature zone is kept unchanged at 750°C, and the temperature field in the low temperature zone is rapidly heated to 1000°C at a rate of 20°C / h and kept at this temperature for 60 hours; the purpose of this stage is to promote the complete reaction of the binary and ternary tellurides formed in the crucible in the high temperature zone to form a homogenized PIT single homogeneous compound;

[0035] (3) Gradient crystallization stage: The temperature in the low temperature zone is kept constant at 1000°C, and the temperature field in the high temperature zone is rapidly changed at a rate of 30°C / h. A temperature field with a gradient of 3°C / cm is formed in the high temperature zone, and gradient crystallization is performed at a rate of 5 mm / h. After 200 mm of gradient crystallization, gradient crystallization is completed;

[0036] (4) Cooling stage: The high temperature zone is cooled to room temperature at a rate of 15°C / h, and the low temperature zone is cooled to room temperature at a rate of 50°C / h, thereby obtaining the indium lead telluride polycrystalline material for single crystal growth.

[0037] The schematic diagram of the dual temperature zone synthesis in this embodiment is as follows Figure 1 As shown, Pb+6In+10Te=PbIn6Te 10 The reaction formula uses a dual temperature zone synthesis furnace to prepare the PIT compound and the synthesis product is further purified by horizontal gradient crystallization. The temperature curve diagram in step 3 is as follows Figure 2 shown.

[0038] The photo of the indium lead telluride polycrystalline material obtained in this example is as follows Figure 3 As shown, from Figure 3 It can be seen that the entire multi-crystalline ingot obtained is complete and has good crystal quality, indicating that the overall uniformity is high.

[0039] The indium lead telluride polycrystalline material synthesized in this example was sampled from the left, middle and right sections, and its XRD spectrum was tested as follows: Figure 4 As shown. Figure 4 It can be seen that the components of each segment of the Indium Lead Telluride polycrystalline material are uniform and the crystallinity is uniform overall.

[0040] The Indium Lead Telluride single crystal is grown using the Indium Lead Telluride polycrystalline material prepared in Example 1. The specific method is as follows:

[0041] The indium lead telluride polycrystalline material was crushed into powder in a mortar, 100 g of which was put into a pyrolytic boron nitride crucible, the crucible was placed in a quartz tube with a diameter of 40 mm, and 5.153 g of Te was added to the quartz tube to provide a Te vapor atmosphere; then a molecular pump was used to evacuate the tube to 10 -5 Pa, a quartz tube is melted and sealed by a hydrogen-oxygen flame; the quartz tube is placed in a horizontal Bridgman single crystal growth furnace, and the powdered lead indium telluride polycrystalline material is placed in a constant temperature zone 30°C higher than the melting point for 50 hours, and then PIT single crystal growth is carried out under the conditions of a temperature gradient of 3°C / cm and a growth rate of 0.1mm / h. After the growth is completed, the temperature is cooled to room temperature at a rate of 20°C / h to obtain a lead indium telluride (PIT) single crystal.

[0042] The PIT single crystal is cut into PIT wafers with a thickness of 4.385 mm and double-sided polished. Figure 5 As shown in the absorption curve of the tested PIT wafer, Figure 6 As shown, from Figure 6 It can be seen that the optical absorption of the wafer at 2.09 μm is less than 0.17 cm -1 , which is conducive to using 2.09μm laser to pump output mid-infrared and far-infrared lasers.

[0043] The embodiments illustrate that the method of horizontal gradient directional crystallization of the present invention further promotes uniform mixing of the additionally added In2Te3 compound in the polycrystalline ingot, thereby avoiding the deterioration of crystallization quality due to large differences in element distribution in different regions during the single crystal growth process, thereby affecting the optical absorption performance of the crystal.

Claims

1. A method for preparing indium lead telluride polycrystalline material for single crystal growth by horizontal gradient crystallization, characterized in that: The method proceeds as follows:

1. In an inert atmosphere glove box, weigh Pb source, In source and Te source according to the stoichiometric ratio of Pb:In:Te of 1:6:10, weigh additional In2Te3 according to 1% to 7% of the total mass of Pb source, In source and Te source, and weigh out Te to provide atmosphere pressure; 2. Place the Pb source, In source, Te source and additional In2Te3 in one crucible, place Te that provides the atmosphere pressure in another crucible, and then place the two crucibles at both ends of a quartz tube, respectively, and fill the quartz tube with 0.1-0.99atm of inert gas, and then use a hydrogen-oxygen flame to melt and seal the quartz tube; 3. Preparation of PIT polycrystalline material by heating reaction: (1) Reaction stage: The sealed quartz tube is placed in a dual-temperature zone horizontal tube furnace, the Pb source, In source, Te source and additional In2Te3 are placed in the high temperature zone, and Te that provides the atmosphere pressure is placed in the low temperature zone; the high temperature zone is heated to 350-450°C at a rate of 5-20°C / h, kept constant for 3-10 hours, and then continued to be heated to 700-800°C at a rate of 5-10°C / h and maintained for 50-100 hours; during this stage, the low temperature zone is heated to 500°C at a rate of 5-20°C / h, and is kept at 500°C throughout this stage; (2) Homogenization stage: After the reaction stage is completed, the temperature field in the low temperature zone is rapidly raised to 950-1000°C at a rate of 10-30°C / h, and the temperature field in the high temperature zone is kept at 700-800°C for 50-100h; (3) Gradient crystallization stage: The temperature in the low temperature zone is kept constant at 950-1000°C; the temperature field in the high temperature zone is rapidly changed at a rate of 20-50°C / h, forming a temperature field with a gradient of 1-5°C / cm in the high temperature zone, and gradient crystallization is performed at a rate of 0.1-10 mm / h; (4) Cooling stage: After the gradient crystallization is completed, the high temperature zone is cooled to room temperature at a rate of 15 to 30°C / h, and the low temperature zone is cooled to room temperature at a rate of 30 to 60°C / h to obtain the indium lead telluride polycrystalline material for single crystal growth.

2. The method for preparing indium lead telluride polycrystalline material for single crystal growth by horizontal gradient crystallization method according to claim 1, characterized in that: The Pb source described in step 1 is bulk metal elemental lead, powdered metal elemental lead, beaded metal elemental lead or lead telluride compound.

3. The method for preparing indium lead telluride polycrystalline material for single crystal growth by horizontal gradient crystallization method according to claim 1 or 2, characterized in that: The In source described in step 1 is bulk metal element indium, powdered metal element indium, beaded metal element indium or indium tritelluride compound.

4. The method for preparing indium lead telluride polycrystalline material for single crystal growth by horizontal gradient crystallization method according to claim 1 or 2, characterized in that: The Te source described in step 1 is bulk single crystal tellurium, powdered metal tellurium or beaded metal tellurium.

5. The method for preparing indium lead telluride polycrystalline material for single crystal growth by horizontal gradient crystallization method according to claim 1 or 2, characterized in that: The mass of Te for providing the atmosphere pressure in step 1 is 3 to 10 grams.

6. The method for preparing indium lead telluride polycrystalline material for single crystal growth by horizontal gradient crystallization method according to claim 1 or 2, characterized in that: The crucible in step 2 is made of carbon-coated quartz, high-purity corundum, high-purity graphite or high-purity pyrolytic boron nitride.

7. The method for preparing indium lead telluride polycrystalline material for single crystal growth by horizontal gradient crystallization method according to claim 1 or 2, characterized in that: The inert gas in step 2 is N2, Ar or He.

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