Compounds of antimony sulfide, lanthanum, and barium sulfide, and far-infrared birefringent optical crystals of antimony sulfide, lanthanum, and barium sulfide, their preparation methods and applications

Abstract

This invention relates to the compounds barium lanthanum sulfide and barium lanthanum sulfide, as well as their preparation methods and applications in the mid-to-far-infrared birefringent optical crystals. It aims to address the problem of low birefringence in existing mid-to-far-infrared crystals. The chemical formula of the barium lanthanum sulfide of this invention is Ba₂La₂Sb₄S₂. 10 (S2), with a molecular weight of 1424.22, crystallizes in a monoclinic system with space group P21 / c and cell parameters a=8.6373(5), b=14.7336(9), c=15.9161(9), α=γ=90°, β=92.661(2)°. The compound or polycrystalline material is prepared using a high-temperature solution or solid-state method; a single crystal is grown from the polycrystalline material, exhibiting a birefringence of 0.53 at 1064 nm and a large birefringence in the range of 1~14 μm, and is used in optical isolators, circulators, beam shifters, optical polarizers, or optical modulators.

Description

Technical Field

[0001] This invention relates to compounds lanthanum barium sulfide and lanthanum barium sulfide, as well as their preparation methods and applications in the mid- and far-infrared birefringent optical crystals, belonging to the field of birefringent crystals in the mid- and far-infrared band. Background Technology

[0002] Birefringence is the phenomenon where a beam of light propagating in a crystal produces two polarized beams. Of the two polarized beams produced by birefringence, the ordinary ray (o ray) obeys the law of refraction, and its refractive index is expressed as n. o This indicates that the e-ray (extraordinary ray) does not obey the law of refraction, and its refractive index is expressed in terms of n. e This indicates that the angle between two polarized beams is related to the propagation direction and polarization state of the light waves. Crystals exhibiting birefringence are called birefringent crystals. Birefringent crystals play an irreplaceable role in optical devices such as optical isolators, polarizing beam splitters, phase delayers, and electro-optic modulators, and are in high demand, especially in high-precision laser processing, infrared sensing, fiber optic communication, and military optoelectronic systems. The performance of a birefringent crystal device mainly depends on the phase delay (φ) between the o-ray and e-ray, which is directly proportional to the birefringence (∆n) of the material. Simultaneously, the beam splitting capability of a birefringent crystal is also directly proportional to the device thickness (d). An ideal birefringent crystal needs to have the largest possible birefringence within its operating wavelength range.

[0003] Birefringent crystals can be classified according to their application wavelength into deep ultraviolet / ultraviolet birefringent crystals, visible-near-infrared birefringent crystals, and mid-to-far-infrared birefringent crystals. Currently, widely used deep ultraviolet / ultraviolet, visible, and near-infrared birefringent crystals mainly include rutile-TiO2 (0.255@1064 nm), YVO4 (0.208@1064 nm), CaCO3 (0.163@1064 nm), α-BaB2O4 (0.116@1064 nm), and LiNbO3 (0.080@1064 nm). However, these crystals exhibit significant absorption in the infrared band, and their birefringence is relatively low, especially in the mid-to-far-infrared band, thus limiting their effective application in this area. Chalcogenides and phosphorus compounds possess a wide infrared optical transmission range in the mid-to-far-infrared band; commercially available crystals include GaSe, AgGaQ2 (Q = S, Se), ZnGeP2, and CdGeAs2. However, the birefringence values ​​of these commercially available materials are generally below 0.2 in the mid- and far-infrared bands, making them unsuitable for effective application in optical devices in this band. Therefore, there is an urgent need to develop high-performance mid- and far-infrared birefringent crystals with high birefringence and a wide infrared transmission range. Summary of the Invention

[0004] This invention aims to address the technical problem that existing crystals with a wide infrared optical transmission range in the mid- and far-infrared band have birefringence values ​​below 0.2, making them unsuitable for effective application in mid- and far-infrared optical devices. The invention provides compounds Ba₂La₂Sb₄Sb₄ and Ba₂La₂Sb₄ ... 10 (S2) Birefringent crystals have the advantages of both high birefringence (0.53 @ 1064 nm) and wide infrared transmission range (1-14 μm).

[0005] One objective of this invention is to provide a compound, barium lanthanum sulfide, with the chemical formula Ba₂La₂Sb₄S. 10 (S2), with a molecular weight of 1424.22, crystallizes in the monoclinic system, space group P21 / c, with cell parameters a=8.6373(5), b=14.7336(9), c=15.9161(9), α=γ=90°, β=92.661(2)°, and a unit cell volume of 2023.3(2) Å. 3 .

[0006] The second objective of this invention is to provide a method for preparing the compound barium lanthanum sulfide, which employs a high-temperature solution method within a sealed vacuum quartz tube. The specific preparation method is carried out according to the following steps:

[0007] 1. In an inert atmosphere glove box, mix the Ba source, La source, Sb source, and elemental S in a molar ratio of (1~2.5):(0.5~1):2:(6~8) until homogeneous. Place the mixture into a clean graphite crucible, then place the graphite crucible into a quartz tube. Use a vacuum pump to evacuate the quartz tube to 10°C. -1 ~10 -3 After Pa, a melt seal is performed.

[0008] 2. Place the sealed quartz tube from step one into a temperature-controlled muffle furnace, raise the temperature to 850-900℃ at a rate of 10-25℃ / h and hold for 48-72 h, then lower it to room temperature at a rate of 3-5℃ / h to obtain the compound barium lanthanum sulfide, with the chemical formula Ba₂La₂Sb₄S. 10 (S2).

[0009] Furthermore, the Ba source mentioned in step one is Ba or BaS; the La source is La or La2S3; and the Sb source is Sb or Sb2S3.

[0010] The third objective of this invention is to provide a method for preparing polycrystalline antimony-lanthanum-barium sulfide compounds. This method employs a high-temperature solid-state process within a sealed vacuum quartz tube. The specific preparation method is carried out according to the following steps:

[0011] 1. In an inert atmosphere glove box, the Ba source, La source, Sb source and elemental S are ground in a mortar and pestle according to a molar ratio of 2:1:2:(1~1.5) to ensure uniform mixing. The mixture is then placed in a clean graphite crucible, which is then placed inside a quartz tube. Inert gas is introduced into the quartz tube until the reading of the external pressure vacuum gauge reaches -0.095~-0.010 MPa. The quartz tube is then melted and sealed using an oxyhydrogen flame. The Ba source is BaS; the La source is La or La2S3; and the Sb source is Sb2S3.

[0012] 2. Place the sealed quartz tube from step one into a temperature-controlled muffle furnace, raise the temperature to 750-800℃ at a heating rate of 50-65℃ / h and hold for 24-36 h, then lower it to room temperature at a cooling rate of 80-100℃ / h to obtain a polycrystalline material of antimony-sulfur lanthanum barium sulfate, the chemical formula of which is Ba2La2Sb4S. 10 (S2).

[0013] Furthermore, the Ba source mentioned in step one is BaS; the La source is La or La2S3; and the Sb source is Sb2S3.

[0014] The fourth objective of this invention is to provide a solution of lanthanum-barium sulfate (Ba2La2Sb4S). 10 (S2) A method for preparing a mid-to-far-infrared birefringent optical crystal, the method comprising the following steps:

[0015] 1. In a glove box under an inert atmosphere, the compound antimony lanthanum barium sulfate (Ba₂La₂Sb₄S) is placed... 10 (S2) The polycrystalline material and the S source are mixed evenly to obtain a mixture; the mass of the S source is 0.01%~5.00% of the mass of the polycrystalline material of the compound antimony lanthanum barium sulfate; the mixture is loaded into a long quartz tube, and then the quartz tube is evacuated to a vacuum degree of 10 using a vacuum pump. -3 ~10 -5 After Pa, perform melt sealing;

[0016] 2. Place the sealed quartz tube from step one into a temperature-controlled muffle furnace, raise the temperature to 850-900℃ at a heating rate of 15-25℃ / h and hold for 40-50 h, then cool to room temperature at a cooling rate of 0.5-1.5℃ / h to obtain lanthanum-barium sulfide (Ba₂La₂Sb₄S). 10 (S2) Mid- to far-infrared birefringent optical crystal.

[0017] The fifth objective of this invention is to provide a solution of sulfide, antimony, lanthanum, barium (Ba2La2Sb4S). 10 The application of (S2) mid-infrared birefringent optical crystals is to combine sulfur, antimony, lanthanum, and barium (Ba2La2Sb4S)10 (S2) Mid- and far-infrared birefringent optical crystals are used in optical isolators, circulators, beam shifters, optical polarizers, or optical modulators.

[0018] Furthermore, the optical polarizer is a polarizing beam splitter prism.

[0019] Furthermore, the polarizing beam splitter is a Glan prism, a Wollaston prism, or a Lochte prism.

[0020] The compound of this invention, Ba2La2Sb4S, is an antimony-sulfur compound. 10 (S2) is prepared according to the following chemical reaction formula:

[0021] (1)2Ba+2La+4Sb+12S=Ba2La2Sb4S 10 (S2);

[0022] (2)2BaS+2La+4Sb+10S=Ba2La2Sb4S 10 (S2);

[0023] (3)2Ba+La2S3+4Sb+9S=Ba2La2Sb4S 10 (S2);

[0024] (4)2BaS+La2S3+4Sb+7S=Ba2La2Sb4S 10 (S2);

[0025] (5)2Ba+2La+2Sb2S3+6S=Ba2La2Sb4S 10 (S2);

[0026] (6)2BaS+2La+2Sb2S3+4S=Ba2La2Sb4S 10 (S2);

[0027] (7)2Ba+La2S3+2Sb2S3+3S=Ba2La2Sb4S 10 (S2);

[0028] (8)2BaS+La2S3+2Sb2S3+S=Ba2La2Sb4S 10 (S2);

[0029] The preparation method of the polycrystalline sulfur-antimony-lanthanum-barium material of the present invention is carried out according to the following chemical reaction formula:

[0030] (9)2BaS+La2S3+2Sb2S3+S=Ba2La2Sb4S 10 (S2);

[0031] (10)2BaS+2La+2Sb2S3+4S=Ba2La2Sb4S 10 (S2);

[0032] The present invention relates to a sulfur-antimony-lanthanum-barium infrared birefringent optical crystal. This crystal is used in the mid- and far-infrared bands. It is a biaxial crystal with a birefringence between 0.42 (7300 nm) and 0.64 (700 nm), and 0.53 at 1064 nm. It has a large birefringence in the range of 1 to 14 μm. It can be used to fabricate optical components such as Glan prisms, Wollaston prisms and other polarization beam splitters, optical isolators, beam shifters, phase delay devices and electro-optic modulation devices. It has important applications in the fields of photolithography and communications. Attached Figure Description

[0033] Figure 1 The compound Ba2La2Sb4S prepared in Example 9 is an antimony lanthanum barium sulfate compound. 10 XRD curve of (S2).

[0034] Figure 2 The image shows the optical infrared transmission spectrum of the polycrystalline material synthesized in Example 9.

[0035] Figure 3 The image shows the Raman spectrum of the polycrystalline material synthesized in Example 9.

[0036] Figure 4 The antimony-sulfur lanthanum-barium Ba2La2Sb4S grown in Example 11 10 (S2) Schematic diagram of the crystal structure of a mid-to-far-infrared birefringent optical crystal, where a is [Sb4S 10 [cluster; b is [Sb4S] 10 The clusters are arranged along direction a; c is the [Sb4S] as seen from direction a. 10 Cluster; d is [Ba2S] 15 (S2)] cluster; e is... 2 [Ba2S9(S2)] ∞ Chain; f is a [La2S8(S2)] cluster; g is 2 [La2S8(S2)] ∞ Chain; h represents the three-dimensional crystal structure as seen from the a direction.

[0037] Figure 5 This is a graph showing the birefringence calculation in Example 11.

[0038] Figure 6 This is a schematic diagram of the Glan prism used in the mid- and far-infrared band fabricated in Example 14.

[0039] Figure 7This is a schematic diagram of the Wollaston prism for the mid- and far-infrared band fabricated in Example 15.

[0040] Figure 8 This is a schematic diagram of a wedge-shaped birefringent crystal polarization beam splitter used in the mid- and far-infrared band in Example 16, where 1 is the incident light; 2 is the o-light; 3 is the e-light; 4 is the optical axis; and 5 is the crystal.

[0041] Figure 9 This is a schematic diagram of the optical isolator for the mid- and far-infrared band fabricated in Example 17, where 6 represents the light transmission direction and the cuboid is a birefringent crystal. Detailed Implementation

[0042] The beneficial effects of the present invention will be verified using the following examples.

[0043] Example 1: In this example, the chemical reaction is 2Ba + 2La + 4Sb + 12S = Ba2La2Sb4S 10 (S2) The compound barium lanthanum sulfide was prepared by a high-temperature solution method in a closed vacuum quartz tube. The specific operation was carried out according to the following steps:

[0044] 1. In a glove box under a nitrogen atmosphere, weigh out 0.058 g Ba, 0.059 g La, 0.103 g Sb, and 0.081 g S, mix them thoroughly, and place them in a clean graphite crucible. The molar ratio of Ba, La, Sb, and S is 2:2:4:12. Then, place the graphite crucible into a quartz tube with a length of 20 cm and a diameter of 15 mm, and use a vacuum pump to evacuate the quartz tube to a vacuum degree of 10. -2 After Pa, perform melt sealing;

[0045] 2. The sealed quartz tube from step 1 is placed in a temperature-controlled muffle furnace and heated to 900 ℃ at a rate of 10 ℃ / h and held for 72 h. Then, it is cooled to room temperature at a rate of 5 ℃ / h to obtain the compound barium lanthanum sulfide.

[0046] The chemical formula of the compound lanthanum barium sulfide prepared in Example 1, determined by single-crystal diffraction, is Ba₂La₂Sb₄S. 10 (S2).

[0047] Example 2: In this example, the chemical reaction is 2BaS + 2La + 4Sb + 10S = Ba2La2Sb4S 10 (S2) The compound barium lanthanum sulfide was prepared by a high-temperature solution method in a closed vacuum quartz tube. The specific operation was carried out according to the following steps:

[0048] 1. In a glove box under a nitrogen atmosphere, weigh out 0.071 g BaS, 0.059 g La, 0.103 g Sb, and 0.068 g S, mix them thoroughly, and place them in a clean graphite crucible. The molar ratio of BaS, La, Sb, and S is 2:2:4:10. Place the graphite crucible into a quartz tube 20 cm long and 15 mm in diameter, and use a vacuum pump to evacuate the quartz tube to a vacuum level of 10. -3 After Pa, perform melt sealing;

[0049] 2. Place the sealed quartz tube from step one into a temperature-controlled muffle furnace, raise the temperature to 900℃ at a rate of 15℃ / h and hold for 60 h, then lower it to room temperature at a rate of 5℃ / h to obtain the compound barium lanthanum sulfide. The chemical formula of this compound is Ba2La2Sb4S 10 (S2).

[0050] Example 3: In this example, the chemical reaction is 2Ba + La₂S₃ + ​​4Sb + 9S = Ba₂La₂Sb₄S 10 (S2) The compound barium lanthanum sulfide was prepared by a high-temperature solution method in a closed vacuum quartz tube. The specific operation was carried out according to the following steps:

[0051] 1. In a glove box under a nitrogen atmosphere, weigh out 0.058 g Ba, 0.079 g La₂S₃, 0.103 g Sb, and 0.061 g S, mix them thoroughly, and place them in a clean graphite crucible. The molar ratio of Ba, La₂S₃, Sb, and S is 2:1:4:9. Then, place the graphite crucible into a quartz tube with a length of 20 cm and a diameter of 15 mm, and use a vacuum pump to evacuate the quartz tube to a vacuum degree of 10. -1 After Pa, perform melt sealing;

[0052] 2. The sealed quartz tube from step one is placed in a temperature-controlled muffle furnace, heated to 900℃ at a rate of 20℃ / h and held at that temperature for 60h, then cooled to room temperature at a rate of 5℃ / h to obtain the compound barium lanthanum sulfide. The chemical formula of this compound is Ba2La2Sb4S. 10 (S2).

[0053] Example 4: In this example, the chemical reaction is 2BaS + La₂S₃ + ​​4Sb + 7S = Ba₂La₂Sb₄S 10 (S2) The compound barium lanthanum antimony was prepared using a high-temperature solution method in a closed vacuum quartz tube. The specific operation was carried out according to the following steps:

[0054] 1. In a glove box under a nitrogen atmosphere, weigh out 0.071 g BaS, 0.079 g La2S3, 0.103 g Sb, and 0.047 g S, mix them thoroughly, and place them in a clean graphite crucible. The molar ratio of BaS, La2S3, Sb, and S is 2:1:4:7. Then, place the graphite crucible into a quartz tube with a length of 20 cm and a diameter of 15 mm, and use a vacuum pump to evacuate the quartz tube to a vacuum degree of 10. -2 After Pa, perform melt sealing;

[0055] 2. The sealed quartz tube from step one is placed in a temperature-controlled muffle furnace, heated to 880℃ at a rate of 15℃ / h and held for 72 h, then cooled to room temperature at a rate of 5℃ / h to obtain the compound barium lanthanum sulfide. The chemical formula of this compound is Ba2La2Sb4S. 10 (S2).

[0056] Example 5: In this example, the chemical reaction is 2Ba + 2La + 2Sb → 2S3 + 6S = Ba2La2Sb4S 10 (S2) The compound barium lanthanum sulfide was prepared by a high-temperature solution method in a closed vacuum quartz tube. The specific operation was carried out according to the following steps:

[0057] 1. In a glove box under a nitrogen atmosphere, weigh out 0.058 g Ba, 0.059 g La, 0.143 g Sb₂S₃, and 0.041 g S, mix them thoroughly, and place them in a clean graphite crucible. The molar ratio of Ba, La, Sb₂S₃ to S is 2:2:2:6. Then, place the graphite crucible into a quartz tube with a length of 20 cm and a diameter of 15 mm, and use a vacuum pump to evacuate the quartz tube to a vacuum degree of 10. -1 After Pa, perform melt sealing;

[0058] 2. The sealed quartz tube from step one is placed in a temperature-controlled muffle furnace, heated to 850℃ at a rate of 20℃ / h and held at that temperature for 56 h, then cooled to room temperature at a rate of 5℃ / h to obtain the compound barium lanthanum sulfide. The chemical formula of this compound is Ba2La2Sb4S. 10 (S2).

[0059] Example 6: In this example, the chemical reaction is 2BaS + 2La + 2Sb2S3 + 4S = Ba2La2Sb4S 10 (S2) The compound barium lanthanum sulfide was prepared by a high-temperature solution method in a closed vacuum quartz tube. The specific operation was carried out according to the following steps:

[0060] 1. In a glove box under a nitrogen atmosphere, weigh out 0.071 g BaS, 0.059 g La, 0.143 g Sb₂S₃, and 0.041 g S, mix them thoroughly, and place them in a clean graphite crucible. The molar ratio of BaS, La, Sb₂S₃, and S is 2:2:4:4. Place the graphite crucible into a quartz tube 20 cm long and 15 mm in diameter, and use a vacuum pump to evacuate the quartz tube to a vacuum degree of 10. -2 After Pa, perform melt sealing;

[0061] 2. The sealed quartz tube from step one is placed in a temperature-controlled muffle furnace, heated to 880℃ at a rate of 20℃ / h and held at that temperature for 56 h, then cooled to room temperature at a rate of 5℃ / h to obtain the compound barium lanthanum sulfide. The chemical formula of this compound is Ba2La2Sb4S. 10 (S2).

[0062] Example 7: In this example, the chemical reaction is 2Ba + La₂S₃ + ​​2Sb₂S₃ + ​​3S = Ba₂La₂Sb₄S 10 (S2) The compound barium lanthanum sulfide was prepared by a high-temperature solution method in a closed vacuum quartz tube. The specific operation was carried out according to the following steps:

[0063] 1. In a glove box under a nitrogen atmosphere, weigh out 0.058 g Ba, 0.079 g La₂S₃, 0.143 g Sb₂S₃, and 0.020 g S, mix them thoroughly, and place them in a clean graphite crucible. The molar ratio of Ba, La₂S₃, Sb₂S₃ to S is 2:1:2:3. Then, place the graphite crucible into a quartz tube with a length of 20 cm and a diameter of 15 mm, and use a vacuum pump to evacuate the quartz tube to a vacuum degree of 10. -2 After Pa, perform melt sealing;

[0064] 2. The sealed quartz tube from step one is placed in a temperature-controlled muffle furnace, heated to 860℃ at a rate of 25℃ / h and held at that temperature for 56 h, then cooled to room temperature at a rate of 5℃ / h to obtain the compound barium lanthanum sulfide. The chemical formula of this compound is Ba2La2Sb4S. 10 (S2).

[0065] Example 8: In this example, the chemical reaction is 2BaS + La₂S₃ + ​​2Sb₂S₃ + ​​S = Ba₂La₂Sb₄S 10 (S2) The compound barium lanthanum sulfide was prepared by a high-temperature solution method in a closed vacuum quartz tube. The specific operation was carried out according to the following steps:

[0066] 1. In a glove box under a nitrogen atmosphere, weigh out 0.071 g BaS, 0.079 g La2S3, 0.143 g Sb2S3, and 0.007 g S, mix them thoroughly, and place them in a clean graphite crucible. The molar ratio of BaS, La2S3, Sb2S3, and S is 2:1:2:1. Then, place the graphite crucible into a quartz tube with a length of 20 cm and a diameter of 15 mm, and use a vacuum pump to evacuate the quartz tube to a vacuum degree of 10. - 2 After Pa, perform melt sealing;

[0067] b. Place the sealed quartz tube from step one into a temperature-controlled muffle furnace, raise the temperature to 850℃ at a rate of 25℃ / h and hold for 48 h, then lower it to room temperature at a rate of 5℃ / h to obtain the compound barium lanthanum sulfide. The chemical formula of this compound is Ba2La2Sb4S 10 (S2).

[0068] Example 9: In this example, the chemical reaction is 2BaS + La₂S₃ + ​​2Sb₂S₃ + ​​S = Ba₂La₂Sb₄S 10 (S2) Preparation of antimony lanthanum barium sulfate (Ba2La2Sb4S) using a high-temperature solid-state method 10 For the polycrystalline material (S2), the specific operation is as follows:

[0069] 1. In a glove box under a nitrogen atmosphere, weigh 0.71 g BaS, 0.79 g La2S3, 1.43 g Sb2S3 and 0.07 g S and grind them in a mortar for 15 minutes to mix the raw materials evenly and obtain a mixture in which the molar ratio of BaS, La2S3, Sb2S3 and S is 2:1:2:1. Then put the mixture into a clean graphite crucible, put the graphite crucible into a quartz tube, and then fill the quartz tube with argon gas until the reading of the external pressure vacuum gauge reaches -0.099 MPa. Use an oxyhydrogen flame to melt and seal the quartz tube.

[0070] 2. Place the sealed quartz tube from step one into a temperature-controlled muffle furnace, raise the temperature to 750℃ at a rate of 65℃ / h and hold for 24 h, then lower it to room temperature at a rate of 100℃ / h to obtain lanthanum-barium sulfate (Ba₂La₂Sb₄S). 10 (S2) polycrystalline material.

[0071] The compound barium lanthanum sulfide (Ba2La2Sb4S) prepared in Example 9 of this study... 10 (S2) The XRD pattern of the polycrystalline material is shown in Figure 1. It can be seen that the experimentally measured XRD diffraction peaks are consistent with the calculated XRD diffraction peak heights, which verifies the synthesized antimony lanthanum barium sulfate (Ba2La2Sb4S). 10 (S2) Purity of polycrystalline material.

[0072] The compound Ba2La2Sb4S prepared in Example 9 is an antimony lanthanum barium sulfate compound. 10 (S2) Infrared optical transmission spectrum of polycrystalline material as follows Figure 2 As shown, the Raman spectrum is as follows Figure 3 As shown. Test results indicate that Ba2La2Sb4S... 10 (S2) at 500~400 cm -1 It exhibits no significant absorption in the 2.5~20 μm band, covering two important atmospheric windows: 3~5 μm and 8~12 μm, indicating its potential application prospects in the field of infrared optics.

[0073] Example 10: In this example, the chemical reaction is 2BaS + 2La + 2Sb2S3 + 4S = Ba2La2Sb4S 10 (S2) Preparation of antimony lanthanum barium sulfate (Ba2La2Sb4S) using a high-temperature solid-state method 10 For the polycrystalline material (S2), the specific operation is as follows:

[0074] 1. In a glove box under a nitrogen atmosphere, weigh 0.58 g Ba, 0.79 g La2S3, 1.43 g Sb2S3 and 0.2 g S, mix them evenly, and grind them in a mortar for 15 minutes to ensure uniform mixing of the raw materials, thereby obtaining a mixture in which the molar ratio of Ba, La2S3, Sb2S3 and S is 2:1:2:1. Place the mixture into a clean graphite crucible, then place the graphite crucible into a quartz tube, and then fill the quartz tube with argon gas until the reading of the external pressure vacuum gauge reaches -0.098 MPa. Use an oxyhydrogen flame to melt and seal the quartz tube.

[0075] 2. Place the sealed quartz tube from step one into a temperature-controlled muffle furnace, raise the temperature to 800℃ at a rate of 80℃ / h and hold for 36 h, then lower it to room temperature at a rate of 80℃ / h to obtain lanthanum-barium sulfate (Ba₂La₂Sb₄S). 10 (S2) polycrystalline material.

[0076] Example 11: This example describes the growth of lanthanum barium sulfate (Ba2La2Sb4S) using a fluxing method. 10 (S2) Infrared birefringent optical crystal, the specific operation is carried out according to the following steps:

[0077] 1. In a glove box under a nitrogen atmosphere, the compound Ba2La2Sb4S prepared in Example 9 was placed... 10(S2) The polycrystalline material and Sb2S3 are mixed evenly to obtain a mixture; wherein the mass of Sb2S3 is 1.00% of the mass of the compound antimony lanthanum barium sulfate polycrystalline material; the mixture is placed into a quartz tube with a length of 20 cm and a diameter of 35 mm, and then the quartz tube is evacuated to a vacuum degree of 10 using a vacuum pump. -4 After Pa, argon gas is then introduced into the quartz tube until the reading of the external pressure vacuum gauge reaches -0.098 MPa, and the quartz tube is melted and sealed using an oxyhydrogen flame.

[0078] 2. Place the sealed quartz tube from step one into a temperature-controlled muffle furnace, raise the temperature to 850℃ at a rate of 15℃ / h and hold for 50 h, then cool it to room temperature at a rate of 1.0℃ / h to obtain sulfide, antimony, lanthanum, barium (Ba₂La₂Sb₄S). 10 (S2) Mid- to far-infrared birefringent optical crystal.

[0079] Figure 4 The antimony-sulfur lanthanum-barium Ba2La2Sb4S grown in Example 11 10 (S2) Schematic diagram of the crystal structure of a mid-to-far-infrared birefringent optical crystal, where a is [Sb4S 10 [cluster; b is [Sb4S] 10 The clusters are arranged along direction a; c is the [Sb4S] as seen from direction a. 10 Cluster; d is [Ba2S] 15 (S2)] cluster; e is... 2 [Ba2S9(S2)] ∞ Chain; f is a [La2S8(S2)] cluster; g is 2 [La2S8(S2)] ∞ Chain; h represents the three-dimensional crystal structure as seen from the a direction.

[0080] Figure 5 The lanthanum barium sulfate (Ba2La2Sb4S) prepared in Example 11 10 (S2) The birefringence calculation curve of the mid-infrared birefringent optical crystal shows that Ba2La2Sb4S 10 The birefringence of (S2) is between 0.42 (7300 nm) and 0.64 (700 nm).

[0081] Example 12: This example describes the growth of lanthanum barium sulfate (Ba2La2Sb4S) using a fluxing method. 10 (S2) Infrared birefringent optical crystal, the specific operation is carried out according to the following steps:

[0082] 1. In a glove box under a nitrogen atmosphere, the compound Ba2La2Sb4S prepared in Example 9 was placed... 10(S2) The polycrystalline material and Sb2S3 are mixed evenly to obtain a mixture; the mass of Sb2S3 is 2.50% of the mass of the compound antimony lanthanum barium sulfate polycrystalline material; the mixture is placed into a quartz tube with a length of 20 cm and a diameter of 35 mm, and then the quartz tube is evacuated to a vacuum degree of 10 using a vacuum pump. -4 After Pa, argon gas is then introduced into the quartz tube until the reading of the external pressure vacuum gauge reaches -0.095~-0.010 MPa, and the quartz tube is melted and sealed using an oxyhydrogen flame.

[0083] 2. Place the sealed quartz tube from step one into a temperature-controlled muffle furnace, raise the temperature to 850℃ at a rate of 20℃ / h and hold for 45 h, then cool it to room temperature at a rate of 1.0℃ / h to obtain lanthanum-barium sulfate (Ba2La2Sb4S). 10 (S2) Infrared birefringent optical crystal.

[0084] Example 13: This example describes the growth of lanthanum barium sulfate (Ba2La2Sb4S) using a fluxing method. 10 (S2) Infrared birefringent optical crystal, the specific operation is carried out according to the following steps:

[0085] 1. In a glove box under a nitrogen atmosphere, the compound Ba2La2Sb4S prepared in Example 9 was placed... 10 (S2) The polycrystalline material and Sb2S3 are mixed evenly to obtain a mixture; the mass of Sb2S3 is 5.00% of the mass of the compound antimony lanthanum barium sulfate polycrystalline material; the mixture is placed into a quartz tube with a length of 20 cm and a diameter of 35 mm, and then the quartz tube is evacuated to a vacuum degree of 10 using a vacuum pump. -4 After Pa, argon gas is then introduced into the quartz tube until the reading of the external pressure vacuum gauge reaches -0.095~-0.010 MPa, and the quartz tube is melted and sealed using an oxyhydrogen flame.

[0086] 2. Place the sealed quartz tube from step one into a temperature-controlled muffle furnace, raise the temperature to 800℃ at a rate of 25℃ / h and hold for 40 h, then cool to room temperature at a rate of 1.0℃ / h to obtain lanthanum-barium sulfate (Ba2La2Sb4S). 10 (S2) Infrared birefringent optical crystal.

[0087] Example 14: The sulfur-antimony-lanthanum-barium (Ba₂La₂Sb₄S) prepared in Examples 11, 12, and 13 were respectively used. 10 (S2) The method for fabricating a Glan prism using a mid-to-far infrared birefringent optical crystal is as follows: [The text then describes a process involving the fabrication of a prism using a crystal containing sulfur, antimony, lanthanum, and barium (Ba2La2Sb4S)]. 10 (S2) A mid-to-far-infrared birefringent optical crystal, fabricated into two identical crystal prisms, is used in the mid-to-far-infrared band. A schematic diagram of this Glan prism is shown below. Figure 6As shown, the light is incident perpendicularly along the crystallographic axis of the crystal, and the incident plane contains two other crystallographic axes. Two prisms are connected together along the inclined plane by a thin layer of air; or the connecting layer between the two prisms can be replaced with optical adhesive of different refractive indices, thus obtaining polarizing prisms with different apex angles. By adjusting the apex angle of the prism, prism designs within the crystal's transmission band can be achieved. When a beam of light is incident perpendicularly to the incident plane, after passing through the first prism of the Glan prism, the directions of the two beams of light with mutually perpendicular polarization directions are not deflected. The angle of incidence on the inclined plane is equal to the angle between the inclined plane of the prism and the right-angled plane (i.e., the apex angle of the prism). By selecting a suitable prism apex angle, one beam of polarized light undergoes total internal reflection on the inclined plane, and the other beam of polarized light exits after passing through the connecting layer between the two prisms and the second prism.

[0088] Example 15: The sulfur-antimony-lanthanum-barium (Ba₂La₂Sb₄S) prepared in Examples 11, 12, and 13 were respectively... 10 (S2) Fabrication of a Wollaston prism using birefringent crystals: The specific fabrication method is as follows: Two birefringent crystal prisms, consisting of sulfur, antimony, lanthanum, and barium, are processed and then bonded together to form a Wollaston prism. A schematic diagram of the Wollaston prism structure is shown below. Figure 7 As shown, the two prisms have the same apex angle, but the crystallographic axes contained in the incident and exit surfaces are different. The incident light is incident perpendicularly on the end face of the prism. Inside prism one, two beams of polarized light with mutually perpendicular polarization directions travel at different speeds along the same direction. When the light enters prism two from prism one, the refractive index changes because the crystallographic axis rotates 90° along the incident direction. The two linearly polarized beams are separated due to birefringence. When the two separated beams of polarized light enter the air from prism two, they undergo a second birefringence and are further separated. The greater the birefringence of the crystal, the more favorable it is for the separation of the beams.

[0089] Example 16: The sulfur-antimony-lanthanum-barium (Ba₂La₂Sb₄S) prepared in Examples 11, 12, and 13 were respectively used. 10 (S2) Fabrication of a wedge-shaped birefringent crystal polarization beam splitter using birefringent crystals. A schematic diagram of the wedge-shaped birefringent crystal polarization beam splitter is shown below. Figure 8 As shown, 1 represents the incident light; 2 represents the o-ray; 3 represents the e-ray; 4 represents the optical axis; and 5 represents the crystal. A wedge-shaped birefringent crystal, with the direction of light passing through it along the crystal's y-axis, allows a beam of natural light to be incident along the optical principal axis y-axis. After passing through the crystal, the light can be split into two linearly polarized beams. The greater the birefringence, the farther the two beams can be separated, facilitating beam separation.

[0090] Example 17: The sulfur-antimony-lanthanum-barium (Ba₂La₂Sb₄S) prepared in Examples 11, 12, and 13 were respectively used. 10(S2) The optical isolator is fabricated using birefringent crystals. Specifically, a Faraday rotator with its incident beam polarization plane rotated by 45° is placed between a pair of birefringent crystal deflectors placed at 45° angles to each other. This constitutes an optical isolator. A schematic diagram of the optical isolator is shown below. Figure 9 As shown, 6 represents the light transmission direction. The cuboid is a birefringent crystal, which only allows forward-propagating light beams to pass through the system while blocking backward-propagating light beams. Figure 9 'a' indicates that the incident light beam can pass through. Figure 9 The 'b' indicates that the reflected light is blocked.

[0091] Utilizing the high birefringence of sulfur, antimony, lanthanum, and barium (Ba2La2Sb4S) 10 (S2) Birefringent crystals are used to prepare optical devices. Optical devices made from crystals with large birefringence can achieve better results with smaller dimensions, which is beneficial for device miniaturization and large-scale device fabrication.

Claims

1. A compound, antimony sulfide, lanthanum, and barium, characterized in that, The chemical formula of this compound is Ba2La2Sb4S 10 (S2), with a molecular weight of 1424.22, crystallizes in the monoclinic system, space group P21 / c, with cell parameters a=8.6373(5), b=14.7336(9), c=15.9161(9), α=γ=90°, β=92.661(2)°, and a unit cell volume of 2023.3(2) Å. 3 .

2. A method for preparing the compound barium lanthanum sulfide, characterized in that, The specific preparation method is carried out according to the following steps:

1. In an inert atmosphere glove box, mix the Ba source, La source, Sb source, and elemental S in a molar ratio of (1~2.5):(0.5~1):2:(6~8) until homogeneous. Place the mixture into a clean graphite crucible, then place the graphite crucible into a quartz tube. Use a vacuum pump to evacuate the quartz tube to 10°C. -1 ~10 -3 After Pa, perform melt sealing; 2. Place the sealed quartz tube from step one into a temperature-controlled muffle furnace, raise the temperature to 850-900℃ at a rate of 10-25℃ / h and hold for 48-72 h, then lower it to room temperature at a rate of 3-5℃ / h to obtain the compound barium lanthanum sulfide, with the chemical formula Ba₂La₂Sb₄S. 10 (S2).

3. The method for preparing the compound barium lanthanum sulfide according to claim 2, characterized in that, The Ba source mentioned in step one is Ba or BaS; the La source is La or La2S3; and the Sb source is Sb or Sb2S3.

4. A method for preparing a polycrystalline compound of antimony-sulfur, lanthanum, and barium, characterized in that, This method is performed in the following steps:

1. In an inert atmosphere glove box, according to the molar ratio of Ba source, La source, Sb source and elemental S 2:1:2:(1~1.5), grind Ba source, La source, Sb source and elemental S in a mortar until the raw materials are evenly mixed, then put them into a clean graphite crucible, and then put the graphite crucible into a quartz tube. Fill the quartz tube with inert gas until the reading of the external pressure vacuum gauge reaches -0.095~-0.010 MPa, and use an oxyhydrogen flame to melt and seal the quartz tube.

2. Place the sealed quartz tube from step one into a temperature-controlled muffle furnace, raise the temperature to 750-800℃ at a heating rate of 50-65℃ / h and hold for 24-36 h, then lower it to room temperature at a cooling rate of 80-100℃ / h to obtain a polycrystalline material of antimony-sulfur lanthanum barium sulfate, the chemical formula of which is Ba2La2Sb4S. 10 (S2).

5. The method for preparing a polycrystalline compound of antimony-sulfur, lanthanum, and barium according to claim 4, characterized in that, The Ba source mentioned in step one is BaS; the La source is La or La2S3; and the Sb source is Sb2S3.

6. A method for preparing a far-infrared birefringent optical crystal of sulfur, antimony, lanthanum, and barium, characterized in that, The preparation method is carried out according to the following steps:

1. In a glove box under an inert atmosphere, the compound antimony lanthanum barium sulfate (Ba₂La₂Sb₄S) is placed... 10 (S2) The polycrystalline material and the S source are mixed evenly to obtain a mixture; the mass of the S source is 0.01%~5.00% of the mass of the polycrystalline material of the compound antimony lanthanum barium sulfate; the mixture is loaded into a long quartz tube, and then the quartz tube is evacuated to a vacuum degree of 10 using a vacuum pump. -3 ~10 -5 After Pa, perform melt sealing; 2. Place the sealed quartz tube from step 1 into a temperature-controlled muffle furnace, raise the temperature to 850-900 ℃ at a heating rate of 15-25 ℃ / h and hold for 40-50 h, then cool to room temperature at a cooling rate of 0.5-1.5 ℃ / h to obtain a far-infrared birefringent optical crystal of sulfur, antimony, lanthanum, and barium.

7. The application of the far-infrared birefringent optical crystal of sulfur, antimony, lanthanum, and barium prepared by the method of claim 6, characterized in that, This application involves using antimony, lanthanum, and barium sulfate (Ba2La2Sb4S). 10 (S2) Mid- and far-infrared birefringent optical crystals are used in optical isolators, circulators, beam shifters, optical polarizers, or optical modulators.

8. The application of the far-infrared birefringent optical crystal of sulfur, antimony, lanthanum, and barium according to claim 7, characterized in that, The optical polarizer is a polarizing beam splitter prism.

9. The application of the far-infrared birefringent optical crystal of sulfur, antimony, lanthanum, and barium according to claim 8, characterized in that, The polarizing beam splitter is a Glan prism, a Wollaston prism, or a Lochte prism.

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