A tellurium-based optical crystal material with large birefringence, preparation method thereof, and application thereof

Abstract

The present invention discloses a tellurium-based optical crystal material with large birefringence, a preparation method thereof and an application thereof, and belongs to the technical field of optical materials. 4+ In the cation, an organic π-conjugated ring-o-phenanthroline and a Cl element that is beneficial to the blue shift of the ultraviolet cutoff edge are introduced. Under the condition of ethanol as solvent, Te 4+ was reduced to Te 2+ In addition, the two N on o-phenanthroline contain lone pairs of electrons, making it a good bidentate ligand. In the process of synthesizing crystals, it provides lone electron pairs to Te 2+ Forming a chemical coordination bond, the organic coordination bond allows Te 2+ It shows a neat and consistent planar structure, which makes the groups arranged neatly and uniformly, effectively increasing the optical anisotropy of the compound and obtaining an optical crystal with extremely high birefringence (C 12 H8N2)TeCl2, the birefringence can reach 1.086@546 nm.

Description

Technical Field

[0001] The present invention belongs to the technical field of optical materials, and in particular relates to a tellurium-based optical crystal material with a large birefringence, a preparation method thereof, and an application thereof. Background Art

[0002] Birefringent crystals have the ability to modulate polarized light and can be used as polarization devices in a wide range of applications, including linear optical devices, fiber optic sensors, and advanced optical communication systems. Scientists have worked tirelessly for many years to develop birefringent crystal materials with excellent properties. Some of these crystals, such as MgF2, CaCO3, YVO4, α-BaB2O4 (α-BBO), and TiO2, have emerged as promising candidates for use in polarizers and compensators.

[0003] However, most of the aforementioned birefringent crystals suffer from defects that hinder their practical applications. For example, YVO4 crystals have a large birefringence of approximately 0.216 at 532 nm, but the valence state of the Y element in these crystals is unstable, resulting in poor quality crystals. Furthermore, YVO4 is not transparent below 400 nm, making it unsuitable for direct use in the ultraviolet (UV) region. Calcite crystals, also known as CaCO3, are naturally occurring minerals and contain numerous impurities, hindering their use in the fabrication of high-quality polarizing prisms. α-BaB2O4 crystals undergo phase transitions during growth, making them unstable and difficult to obtain. MgF2 crystals have a very short UV cutoff edge, reaching 110 nm, making them suitable for use in the deep UV region. However, their birefringence is too low, at only 0.012 at 546 nm, making them unsuitable for device miniaturization. Therefore, the exploration of novel optical crystal materials with superior comprehensive properties through rational design strategies is still necessary. Summary of the Invention

[0004] In view of the above-mentioned prior art, the present invention provides a tellurium-based optical crystal material with a large birefringence, a preparation method thereof, and an application thereof, so as to solve the technical problems of low birefringence and poor quality of the existing birefringent materials.

[0005] In order to achieve the above object, the technical solution adopted by the present invention is to provide a tellurium-based optical crystal material with a large birefringence, the chemical composition of the tellurium-based optical crystal material is (C 12 H8N2)TeCl2, space group is Pn , the unit cell parameters are a=4.2730(3) Å, b=9.8453(7) Å, c=14.7866(10) Å, α =90°, β =97.013(7), γ =90°, Z=2.

[0006] The present invention also discloses a method for preparing the above-mentioned tellurium-based optical crystal material with large birefringence, comprising the following steps:

[0007] S1: C 12 H8N2·H2O and TeCl4 are dissolved in a mixed solvent and stirred for 15 to 25 minutes to obtain a mixture; the mixed solvent is prepared by mixing hydrochloric acid and anhydrous ethanol;

[0008] S2: reacting the mixture in a sealed environment at 140-160°C for 6-9 days, then cooling to room temperature, collecting crystals to obtain a primary product;

[0009] S3: Clean the primary product.

[0010] Further, C 12 The molar ratio of H8N2·H2O and TeCl4 is 1:2.5.

[0011] Furthermore, the volume ratio of hydrochloric acid to anhydrous ethanol in the mixed solvent is 3:40.

[0012] Furthermore, the mixture C 12 The concentration of H8N2·H2O is 0.04~0.05 mol / L.

[0013] Furthermore, in S2, the reaction temperature is 150° C. and the reaction time is 7 days.

[0014] Furthermore, the cooling rate in S2 is 5°C / min.

[0015] Furthermore, the cleaning method in S3 is to rinse with anhydrous ethanol 3 to 5 times.

[0016] The invention also discloses the application of the tellurium-based optical crystal material with large birefringence in preparing polarization devices.

[0017] The beneficial effects of the present invention are:

[0018] 1. The present invention has a stereochemically active lone pair of electrons in Te 4+ In the cation, an organic π-conjugated ring-o-phenanthroline and a Cl element that is beneficial to the blue shift of the ultraviolet cutoff edge are introduced. Under the condition of ethanol as solvent, Te 4+ was reduced to Te 2+ In addition, the two N on o-phenanthroline contain lone pairs of electrons, making it a good bidentate ligand. In the process of synthesizing crystals, it provides lone electron pairs to Te 2+ Forming a chemical coordination bond, the organic coordination bond allows Te 2+It shows a neat and consistent planar structure, which makes the groups arranged neatly and uniformly, effectively increasing the optical anisotropy of the compound and obtaining an optical crystal with extremely high birefringence - (C 12 H8N2)TeCl2, the birefringence can reach 1.086@546 nm.

[0019] 2. Among the optical crystals reported in the prior art, most are tetravalent Te. The optical crystals prepared by the present invention (C 12 H8N2)TeCl2 introduced divalent Te into optical crystals for the first time, obtaining a crystal structure with a planar quadrilateral configuration and neat and consistent arrangement. While improving the optical properties of the crystals, it also expanded the application of tellurium-containing compounds in crystals.

[0020] 3. The tellurium-based optical crystal material with large birefringence prepared by the present invention has stable comprehensive performance, can remain stable in air and ethanol, and has good physical and chemical stability. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 Tellurium-based optical crystal material (C 12 H8N2)TeCl2 three-dimensional framework structure;

[0022] Figure 2 Tellurium-based optical crystal material (C 12 H8N2)TeCl2 X-ray powder diffraction pattern;

[0023] Figure 3 Tellurium-based optical crystal material (C 12 H8N2)TeCl2 thermogravimetric spectrum;

[0024] Figure 4 Tellurium-based optical crystal material (C 12 Infrared spectrum of H8N2)TeCl2;

[0025] Figure 5 Tellurium-based optical crystal material (C 12 UV-visible diffuse reflectance spectrum of H8N2)TeCl2;

[0026] Figure 6 Tellurium-based optical crystal material (C 12 Birefringence test chart of H8N2)TeCl2. 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 tellurium-based optical crystal material with a large birefringence is prepared by the following steps:

[0030] S1: C 12 H8N2·H2O and TeCl4 were dissolved in a mixed solvent and stirred for 20 min to obtain a mixture; wherein, C 12 The molar ratio of H8N2·H2O to TeCl4 is 1:2.5; the mixed solvent is composed of hydrochloric acid and anhydrous ethanol in a volume ratio of 3:40; C 12 The concentration of H8N2·H2O is 0.047 mol / L

[0031] S2: The mixture was placed into the inner lining of a hydrothermal reactor, and the hydrothermal reactor was placed in a 150°C forced air drying oven and heated continuously for 7 days. The temperature was then cooled to room temperature at a rate of 5°C / hour to obtain light yellow flaky crystals, i.e., the primary product.

[0032] S3: Rinse the primary product with anhydrous ethanol 4 times.

[0033] Example 2

[0034] A tellurium-based optical crystal material with a large birefringence is prepared by the following steps:

[0035] S1: C 12 H8N2·H2O and TeCl4 were dissolved in a mixed solvent and stirred for 15 min to obtain a mixture; wherein, C 12 The molar ratio of H8N2·H2O to TeCl4 is 1:2.5; the mixed solvent is composed of hydrochloric acid and anhydrous ethanol in a volume ratio of 3:40; C 12 The concentration of H8N2·H2O is 0.04 mol / L

[0036] S2: The mixture was placed into the inner lining of a hydrothermal reactor, and the hydrothermal reactor was placed in a forced air drying oven and heated continuously for 6 days at 160°C, and then cooled to room temperature at a rate of 5°C / hour to obtain light yellow flaky crystals, i.e., the primary product;

[0037] S3: Rinse the primary product with anhydrous ethanol three times.

[0038] Example 3

[0039] A tellurium-based optical crystal material with a large birefringence is prepared by the following steps:

[0040] S1: C 12 H8N2·H2O and TeCl4 were dissolved in a mixed solvent and stirred for 25 min to obtain a mixture; wherein, C 12The molar ratio of H8N2·H2O to TeCl4 is 1:2.5; the mixed solvent is composed of hydrochloric acid and anhydrous ethanol in a volume ratio of 3:40; C 12 The concentration of H8N2·H2O is 0.05 mol / L

[0041] S2: The mixture was placed into the inner lining of a hydrothermal reactor, and the hydrothermal reactor was placed in a forced air drying oven and heated continuously for 9 days at 140°C, and then cooled to room temperature at a rate of 5°C / hour to obtain light yellow flaky crystals, i.e., the primary product;

[0042] S3: Rinse the primary product with anhydrous ethanol 5 times.

[0043] Experimental example

[0044] The properties of the tellurium-based optical crystal materials prepared in Examples 1 to 3 are similar. The properties of the tellurium-based optical crystal material in Example 1 are described as an example.

[0045] 1. Tellurium-based optical crystal materials with large birefringence (C 12 Structural Analysis of H8N2)TeCl2

[0046] Tellurium-based optical crystal materials (C 12 The crystallographic data of H8N2)TeCl2 are shown in Table 1.

[0047] Table 1 Tellurium-based optical crystal materials (C 12 Crystallographic data of H8N2)TeCl2

[0048] Formula Mass 316.35 Crystal system Monoclinic system Space group (Å) 4.2730(3) (Å) 9.8453(7) (Å) 14.7866(10) 90 97.013(7) 90 <![CDATA[ V (Oh 3 )]]> 617.40(8) 2 <![CDATA[ ρ (calcd) (g / cm 3 )]]> 2.037 Temperature (K) 302.75(10) (Å) 0.71073 (000) 360.0 <![CDATA[ µ (mm -1 )]]> 2.818 <![CDATA[ R 1, wxya 2( I >2 ( I )) a ]]> 0.0432 / 0.1005 <![CDATA[GOF on F 2 ]]> 1.046

[0049] Note: a R 1( F ) = ∑|| F o |−| F c || / ∑| F o |. wxya 2( F o 2 ) = [∑w( F o 2 − F c 2 ) 2 / ∑w( F o 2 ) 2 ] 1 / 2

[0050] Tellurium-based optical crystal materials (C 12 H8N2)TeCl2, space group is Pn , the unit cell parameters are a=4.2730(3) Å, b=9.8453(7) Å, c=14.7866(10) Å, α =90°, β =97.013(7), γ =90°, Z=2. In (C 12 The symmetrical unit of H8N2)TeCl2 contains an independent o-phenanthroline ring, an independent Te atom, and two independent Cl atoms. Each Te atom forms a coordination bond with the two lone-pair N atoms on o-phenanthroline and a covalent bond with the two Cl atoms. The Te-Cl and Te-N bond lengths range from 2.630(3)-2.640(3) and 2.282(10)-2.299(9), respectively. The shape is butterfly-shaped, and the entire ring is in the same plane, arranged neatly and uniformly, forming a structure such as Figure 1 The 0-dimensional cluster structure shown.

[0051] 2. Tellurium-based optical crystal materials with large birefringence (C 12 Characterization of H8N2)TeCl2

[0052] (1) Tellurium-based optical crystal materials (C 12 X-ray Powder Diffraction Analysis of H8N2)TeCl2

[0053] Figure 2 It is a tellurium-based optical crystal material (C 12 H8N2)TeCl2 X-ray powder diffraction pattern. It can be seen from the figure that the XRD pattern of the experimental test is basically consistent with the XRD pattern of the single crystal fitting, indicating that (C 12 The H8N2)TeCl2 sample is pure phase and can be used for the next test, which also shows that the single crystal structure analysis is correct.

[0054] (2) Tellurium-based optical crystal materials (C 12 Thermogravimetric Analysis of H8N2)TeCl2

[0055] Tellurium-based optical crystal materials (C 12 Thermogravimetric spectrum of H8N2)TeCl2 is as follows Figure 3 As shown in the figure, it can be seen that (C 12 H8N2)TeCl2 can remain stable within 135℃ and begins to lose weight between 135℃ and 700℃, with a total weight loss rate of 33%.

[0056] (3) Tellurium-based optical crystal materials (C 12 Infrared Spectrum Analysis of H8N2)TeCl2

[0057] Tellurium-based optical crystal materials (C 12 The infrared spectrum of H8N2)TeCl2 is as follows Figure 4 As shown, (C 12 H8N2)TeCl2 has a wavelength of 4000~800 cm -1 The wide transmission window appears at 3100 cm -1 The peaks on the left and right are the stretching vibrations of the unsaturated CH bond in the o-phenanthroline ring, appearing at 1600 cm -1 The nearby peaks are the stretching vibrations of C=N and C=C on the ring, appearing at 1589~1452 cm -1 The peak is the vibration peak of o-phenanthroline ring, which is between 701 and 808 cm -1 and 1517 cm -1 The absorption peak appears, indicating that o-phenanthroline is coordinated and the characteristic peak is red-shifted to 739 cm -1 and 853 cm -1 Nearby is the bending vibration absorption peak of the CH bond outside the ring plane. This shows that phenanthroline and Te 2+ Coordination is carried out to form a coordination bond.

[0058] (4) Tellurium-based optical crystal materials (C 12 Analysis of UV-Vis Diffuse Reflectance Spectra of H8N2)TeCl2

[0059] Tellurium-based optical crystal materials (C 12 UV-visible diffuse reflectance of H8N2)TeCl2 Figure 5 As shown in the figure, we can see that (C 12 The experimental band gap of TeCl2 is 3.20 eV, and the corresponding UV absorption cutoff edge is 387.5 nm. The results show that (C 12 H8N2)TeCl2 is an ultraviolet optical material with application prospects.

[0060] (5) Tellurium-based optical crystal materials (C 12 Birefringence Analysis of H8N2)TeCl2

[0061] The polarization of tellurium-based optical crystal materials (C 12 H8N2)TeCl2 birefringence, the results are as follows Figure 6 The test results show that tellurium-based optical crystal materials (C 12 H8N2)TeCl2 exhibits a large birefringence, which can reach 1.086@546 nm.

[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 tellurium-based optical crystal material with a large birefringence, characterized in that: The chemical composition of the tellurium-based optical crystal material is (C 12 H8N2)TeCl2, where C 12 H8N2 is o-phenanthroline; the space group of tellurium-based optical crystal materials is Pn , the unit cell parameters are a=4.2730(3) Å, b=9.8453(7) Å, c=14.7866(10) Å, α =90°, β =97.013(7)°, γ =90°, Z=2.

2. The method for preparing the tellurium-based optical crystal material with large birefringence according to claim 1, characterized in that: The following steps are involved: S1: Phenanthroline hydrate C 12 H8N2·H2O and TeCl4 are dissolved in a mixed solvent and stirred for 15 to 25 minutes to obtain a mixture; the mixed solvent is a mixture of hydrochloric acid and anhydrous ethanol; the C 12 The molar ratio of H8N2·H2O and TeCl4 is 1:2.5; S2: reacting the mixture in a sealed environment at 140-160°C for 6-9 days, then cooling to room temperature, collecting crystals to obtain a primary product; S3: Clean the primary product.

3. The preparation method according to claim 2, wherein: The volume ratio of hydrochloric acid to anhydrous ethanol in the mixed solvent is 3:

40.

4. The preparation method according to claim 3, wherein: The mixture contains C 12 The concentration of H8N2·H2O is 0.04~0.05 mol / L.

5. The preparation method according to claim 2, wherein: In S2, the reaction temperature is 150°C and the reaction time is 7 days.

6. The preparation method according to claim 2, wherein: The cooling rate in S2 is 5 °C / min.

7. The preparation method according to claim 2, characterized in that: The cleaning method in S3 is to rinse with anhydrous ethanol 3 to 5 times.

8. Use of the tellurium-based optical crystal material with large birefringence according to claim 1 in the preparation of polarization devices.

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