A birefringent crystal and its preparation method

Abstract

The present invention discloses a birefringent crystal and a preparation method thereof, belonging to the field of optical material technology. The chemical formula of the birefringent crystal is SbTeO3F; the space group of the birefringent crystal is P212121; the unit cell parameters are α=90°, β=90°, γ=90°, and Z=4. During preparation, an antimony-containing compound and a tellurium-containing compound are dissolved in a mixed solution, which is then filtered, and the filtrate is allowed to stand at room temperature for 4 to 5 days; the precipitated crystals are then collected and washed to obtain the obtained product. The birefringent crystal preparation process of the present invention is simple and has good repeatability. It can reduce the preparation cost while improving the yield. The obtained birefringent crystal has a large birefringence and can remain stable in both air and water, and has good physical and chemical stability.

Description

Technical Field

[0001] The present invention belongs to the technical field of optical materials, and in particular relates to a birefringent crystal and a preparation method thereof. Background Art

[0002] When a beam of light strikes the surface of a crystal, it produces two refracted beams, a phenomenon known as birefringence. Crystals capable of this phenomenon are called birefringent crystals. This birefringence is a crucial optical performance parameter for optoelectronic functional materials. This property can be exploited to modulate and detect the polarization state of light, generating linearly polarized light and achieving beam displacement. Therefore, birefringent crystal materials are widely used in the manufacture of key components such as optical isolators, optical modulators, polarization beam splitters, and polarizer prisms.

[0003] Currently, the main birefringent crystals used commercially include TiO2 (Δn = 0.256 @ 546 nm), CaCO3 (Δn = 0.172 @ 532 nm), YVO4 (Δn = 0.204 @ 53 nm), LiNbO3 (Δn = 0.074 @ 546 nm), and α-BaB2O4 (Δn = 0.122 @ 546 nm). Natural birefringent crystals TiO2 and CaCO3 are limited in their application due to quality issues such as impurities and defects. Artificial birefringent crystals CaCO3, YVO4, and LiNbO3 are relatively expensive to synthesize, and some birefringent crystals suffer from low transmittance and low birefringence. Therefore, the search for high-performance birefringent crystal materials is of great significance. Summary of the Invention

[0004] In view of the above-mentioned prior art, the present invention provides a birefringent crystal and a preparation method thereof to solve the technical problems of the prior art such as high preparation cost of birefringent materials, low light transmittance and small birefringence.

[0005] In order to achieve the above object, the technical solution adopted by the present invention is: to provide a birefringent crystal, the chemical formula of the birefringent crystal is SbTeO3F; the space group of the birefringent crystal is P212121; the unit cell parameters are α=90°, β=90°, γ=90°, Z=4.

[0006] The present invention also provides a method for preparing the above-mentioned birefringent crystal, comprising the following steps:

[0007] S1: mixing an antimony-containing compound and a tellurium-containing compound, dissolving the mixture in a mixed solution, and stirring at a stirring rate of 800 to 1200 rpm for 15 to 25 minutes to obtain a precursor solution; the mixed solution is obtained by mixing hydrofluoric acid and distilled water;

[0008] S2: Filter the precursor solution, and let the filtrate stand at room temperature for 4 to 5 days;

[0009] S3: Collect the precipitated crystals and wash them to obtain the product.

[0010] On the basis of the above technical solution, the present invention can also be improved as follows.

[0011] Furthermore, the antimony-containing compound is SbF3, and the tellurium-containing compound is TeO2.

[0012] Furthermore, the molar ratio of SbF3 to TeO2 is 4:1.

[0013] Furthermore, the material-liquid ratio of the mixture to the mixed solution is 1 g: 3-5 mL.

[0014] Furthermore, the mixed solution is prepared by mixing hydrofluoric acid and distilled water in a volume ratio of 1:25 to 35.

[0015] Furthermore, the mixed solution is prepared by mixing hydrofluoric acid and distilled water in a volume ratio of 1:30.

[0016] Furthermore, the stirring rate in S1 is 1000 rpm and the stirring time is 20 min.

[0017] Furthermore, the cleaning method in S3 is to rinse with distilled water and ethanol 1 to 3 times respectively.

[0018] The beneficial effects of the present invention are:

[0019] 1. The birefringent crystal preparation process of the present invention is simple and has good repeatability, which can reduce the preparation cost and improve the yield.

[0020] 2. The present invention combines two cations ([SbO3F] 4- and [TeO3] 3- ) are combined together to form a birefringent crystal with a special unit cell structure. The resulting birefringent crystal has a large birefringence and can remain stable in both air and water, with good physical and chemical stability. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 The formation mechanism diagram of the birefringent crystal SbTeO3F; where (a) is [SbO3F] 4- and [TeO3] 3- (b) is the three-dimensional framework structure of SbTeO3F;

[0022] Figure 2 is the X-ray powder diffraction pattern of birefringent crystal SbTeO3F;

[0023] Figure 3 This is the thermogravimetric spectrum of birefringent crystal SbTeO3F;

[0024] Figure 4 is the infrared spectrum of birefringent crystal SbTeO3F;

[0025] Figure 5 This is the UV-visible diffuse reflectance spectrum of the birefringent crystal SbTeO3F;

[0026] Figure 6 This is the birefringence test chart of the birefringent crystal SbTeO3F. DETAILED DESCRIPTION

[0027] The specific implementation methods of the present invention are described in detail below with reference to the embodiments.

[0028] Example 1

[0029] A birefringent crystal having a chemical formula of SbTeO3F is prepared by the following steps:

[0030] S1: SbF3 and TeO2 were mixed at a molar ratio of 4:1, and then the mixture was dissolved in a mixed solution at a material-liquid ratio of 1 g:4 mL, and then stirred at a stirring rate of 1000 rpm for 20 minutes to obtain a precursor solution; the mixed solution was prepared by mixing hydrofluoric acid and distilled water at a volume ratio of 1:30;

[0031] S2: Filter the precursor solution with filter paper, and let the filtrate stand at room temperature for 5 days;

[0032] S3: Collect the precipitated crystals and rinse them with distilled water and ethanol twice each.

[0033] Example 2

[0034] A birefringent crystal having a chemical formula of SbTeO3F is prepared by the following steps:

[0035] S1: SbF3 and TeO2 were mixed in a molar ratio of 4:1, and then the mixture was dissolved in a mixed solution at a material-liquid ratio of 1 g:3 mL, and then stirred at a stirring rate of 800 rpm for 25 minutes to obtain a precursor solution; the mixed solution was prepared by mixing hydrofluoric acid and distilled water in a volume ratio of 1:35;

[0036] S2: Filter the precursor solution with filter paper, and let the filtrate stand at room temperature for 4 days;

[0037] S3: Collect the precipitated crystals and rinse them with distilled water and ethanol once each.

[0038] Example 3

[0039] A birefringent crystal having a chemical formula of SbTeO3F is prepared by the following steps:

[0040] S1: SbF3 and TeO2 were mixed in a molar ratio of 4:1, and then the mixture was dissolved in a mixed solution at a material-liquid ratio of 1 g:5 mL, and then stirred at a stirring rate of 1200 rpm for 15 minutes to obtain a precursor solution; the mixed solution was prepared by mixing hydrofluoric acid and distilled water in a volume ratio of 1:25;

[0041] S2: Filter the precursor solution with filter paper, and let the filtrate stand at room temperature for 5 days;

[0042] S3: Collect the precipitated crystals and rinse them with distilled water and ethanol three times each.

[0043] Experimental example

[0044] The performance of the birefringent crystals prepared in Examples 1 to 3 is similar, and the performance of the birefringent crystal in Example 1 is described below by taking it as an example.

[0045] 1. Structural analysis of birefringent crystal SbTeO3F

[0046] The crystallographic data of the birefringent crystal SbTeO3F are shown in Table 1.

[0047] Table 1 Crystallographic data of birefringent crystal SbTeO3F

[0048]

[0049] Note: a R1(F)=∑||F o |-|F c || / ∑|F o |.wR2(F o 2 )=[∑w(F o 2 -F c 2 ) 2 / ∑w(F o 2 ) 2 ] 1 / 2

[0050] The compound SbTeO3F crystallizes in the orthorhombic system with space group P212121 and unit cell parameters of α=90°,β=90°,γ=90°,Z=4. The formation process of birefringent crystal SbTeO3F is as follows Figure 1As shown in the figure, it can be seen that the asymmetric unit of SbTeO3F contains an independent Sb atom, an independent Te atom, three independent O atoms, and an independent F atom; each Sb atom is coordinated with three O atoms and one F atom to form a distorted [SbO3F] with a seesaw structure. 4- Tetrahedral group ( Figure 1 a), where the Sb-O and Sb-F bond lengths range from 1.991(5) to 2.292(5) and 2.055(4), respectively; each Te atom is coordinated with three O atoms to form a trigonal pyramidal [TeO3] 3- Group ( Figure 1 a), whose bond length ranges from 1.886(5) to 1.913(5); [SbO3F] 4- Group and [TeO3] 3- The groups are connected by shared O atoms to form a three-dimensional framework structure with alternating arrangements of 4-MRs and 8-MRs ( Figure 1 b).

[0051] 2. Characterization of birefringent crystal SbTeO3F

[0052] (1) X-ray powder diffraction analysis of birefringent crystal SbTeO3F

[0053] Figure 2 This is the X-ray powder diffraction pattern of birefringent SbTeO3F crystals. As can be seen from the figure, the experimental XRD pattern is essentially consistent with the single crystal fitted XRD pattern, indicating that the SbTeO3F sample is pure and suitable for further testing. It also confirms that the single crystal structure analysis is correct. After the SbTeO3F sample was exposed to air and water for 120 hours, another XRD test was performed, revealing that the XRD pattern remained essentially unchanged, demonstrating the good physical and chemical stability of the SbTeO3F compound.

[0054] (2) Thermogravimetric analysis of birefringent crystal SbTeO3F

[0055] Thermogravimetric spectrum of birefringent crystal SbTeO3F Figure 3 As shown in the figure, it can be seen that the birefringent crystal SbTeO3F can remain stable within 146℃, and begins to lose weight in the range of 146℃~800℃, with a total weight loss rate of 19.7%.

[0056] (3) Infrared spectroscopy analysis of birefringent crystal SbTeO3F

[0057] The infrared spectrum of birefringent crystal SbTeO3F is as follows Figure 4 As shown in the figure, it can be seen that the birefringent crystal SbTeO3F has a wavelength of 4000~800cm -1The wide window appears at 744cm -1 / 624cm -1 The peak at 509 cm is the asymmetric stretching vibration of the Sb-O / F bond and the Te-O bond. -1 The peaks at are the bending vibrations of Sb-O / F and Te-O bonds.

[0058] (4) Analysis of UV-visible diffuse reflectance spectra of birefringent crystal SbTeO3F

[0059] The UV-visible diffuse reflection of birefringent crystal SbTeO3F is as follows Figure 5 As shown in the figure, it can be seen that the experimental band gap of SbTeO3F is 4.08eV and the corresponding ultraviolet absorption cutoff edge is 303nm. The results show that SbTeO3F is an ultraviolet optical material with application prospects.

[0060] (5) Birefringence test of birefringent crystal SbTeO3F

[0061] The birefringence of the refractive crystal SbTeO3F was measured using a ZEISS Axio A1 polarizing microscope at a wavelength of 546 nm. Figure 6 The test results show that the compound SbTeO3F exhibits a large birefringence of 0.298@546nm, indicating that SbTeO3F is an excellent birefringent material.

[0062] Although the specific embodiments of the present invention have been described in detail in conjunction with the embodiments, this should not be construed as limiting the scope of protection of this patent. Within the scope described by the claims, various modifications and variations that can be made by those skilled in the art without creative work still fall within the scope of protection of this patent.

Claims

1. A birefringent crystal, characterized in that: The chemical formula of the birefringent crystal is SbTeO3F; the space group of the birefringent crystal is P 212121; the unit cell parameters are a = 4.9843(2)Å, b = 6.7932(3)Å, c = 11.0144(5)Å, α = 90°, β = 90°, γ = 90°, Z = 4.

2. The method for preparing a birefringent crystal according to claim 1, wherein The following steps are involved: S1: mixing an antimony-containing compound and a tellurium-containing compound, dissolving the mixture in a mixed solution, and stirring at a stirring rate of 800-1200 rpm for 15-25 minutes to obtain a precursor solution; the mixed solution is obtained by mixing hydrofluoric acid and distilled water; the antimony-containing compound is SbF3, and the tellurium-containing compound is TeO2; the molar ratio of SbF3 to TeO2 is 4:1; S2: Filter the precursor solution and let the filtrate stand at room temperature for 4-5 days; S3: Collect the precipitated crystals and wash them to obtain the product.

3. The preparation method according to claim 2, wherein: The material-liquid ratio of the mixture to the mixed solution is 1 g:3-5 mL.

4. The preparation method according to claim 2, wherein: The mixed solution is prepared by mixing hydrofluoric acid and distilled water in a volume ratio of 1:25-35.

5. The preparation method according to claim 4, characterized in that: The mixed solution is prepared by mixing hydrofluoric acid and distilled water in a volume ratio of 1:

30.

6. The preparation method according to claim 2, wherein: The stirring rate in S1 was 1000 rpm and the stirring time was 20 min.

7. The preparation method according to claim 2, characterized in that: The cleaning method in S3 is to rinse with distilled water and ethanol 1 to 3 times each.

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