Tellurium-based optical crystal material with large birefringence as well as preparation method and application of tellurium-based optical crystal material

Abstract

The invention discloses a tellurium-based optical crystal material with large birefringence and a preparation method and application thereof, and belongs to the technical field of optical materials. Organic pi conjugated ring-phenanthroline and a Cl element beneficial to blue shift of an ultraviolet cut-off side are introduced into Te4 + cations with lone pair electrons with stereochemical activity, Te4 + is reduced to obtain Te2 + cations under the condition that ethanol is used as a solvent, in addition, two N on phenanthroline contain lone pair electrons and are good bidentate ligands, and the organic pi conjugated ring-phenanthroline-Cl-Te < 4 + >-Te2 +-Te < 2 + >-Te < 2 + >-Te < 2 + >-Te < 2 + >-Te < 2 + >-Te < 2 + >-Te < 2 + >- In the crystal synthesis process, lone electron pairs and Te < 2 + > are provided to form chemical coordinate bonds and organic coordinate bonds, so that the Te < 2 + > shows a neat and consistent plane structure, groups are neatly and consistently arranged, the optical anisotropy of the compound is effectively improved, the optical crystal-(C12H8N2) TeCl2 with the great birefringence is obtained, and the birefringence can reach 1.086 nm and 546 nm.

Description

Technical Field

[0001] The 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 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 such as linear optical devices, fiber optic sensors, and advanced optical communication systems. After years of unremitting efforts by scientists, many birefringent crystal materials with excellent performance have been obtained. Some crystals have stood out and are widely used in polarizers and compensators, such as MgF2, CaCO3, YVO4, α-BaB2O4 (α-BBO), TiO2, etc.

[0003] However, most of the above-mentioned birefringent crystals have some defects, which hinder their application in real life. For example, YVO4 crystal has a large birefringence of about 0.216@532 nm, but the valence state of the Y element in the crystal is not very stable, resulting in poor quality of the obtained crystal; in addition, YVO4 cannot transmit the light region below 400 nm and cannot be directly used in the ultraviolet (UV) light region. Calcite crystal, namely CaCO3, is a natural mineral with many impurities, which hinders its use in the manufacture of polarizing prisms with high optical quality. α-BaB2O4 crystal has phase transition during growth and is not very stable, making it difficult to obtain high-quality crystals. MgF2 crystal has a very short ultraviolet cutoff edge of up to 110 nm and can be used in the deep ultraviolet region, but the birefringence of the crystal is too small, only 0.012 at 546 nm, which is not conducive to device miniaturization. Therefore, it is still necessary to explore new optical crystal materials with excellent comprehensive performance by adopting reasonable design strategies. 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 and a preparation method and 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: 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; S2: react the mixture in a closed environment at 140-160°C for 6-9 days, then cool to room temperature, collect crystals, and obtain a primary product; S3: Wash the primary product.

[0007] Further, C 12 The molar ratio of H8N2·H2O and TeCl4 is 1:2.5.

[0008] Furthermore, the volume ratio of hydrochloric acid to anhydrous ethanol in the mixed solvent is 3:40.

[0009] Furthermore, the mixture C 12 The concentration of H8N2·H2O is 0.04~0.05 mol / L.

[0010] Furthermore, in S2, the reaction temperature is 150°C and the reaction time is 7 days.

[0011] Furthermore, the cooling rate in S2 is 5 °C / min.

[0012] Furthermore, the cleaning method in S3 is to rinse with anhydrous ethanol for 3 to 5 times.

[0013] The invention also discloses the application of the tellurium-based optical crystal material with large birefringence in the preparation of polarization devices.

[0014] The beneficial effects of the present invention are: 1. The present invention is to use Te with stereochemically active lone pair electrons 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+ The Te 2+ In addition, the two N atoms on o-phenanthroline contain lone pairs of electrons, making it a good bidentate ligand. In the process of synthesizing crystals, it provides lone pairs of electrons to form a bond with Te 2+ Forming chemical coordination bonds, organic coordination bonds allow Te 2+ It shows a uniform planar structure, which makes the groups arranged uniformly, effectively increases the optical anisotropy of the compound, and obtains an optical crystal with extremely high birefringence - (C 12H8N2)TeCl2, the birefringence can reach 1.086@546 nm.

[0015] 2. The optical crystals reported in the prior art are basically tetravalent Te. The optical crystals prepared by the present invention (C 12 H8N2)TeCl2 introduced divalent Te into optical crystals for the first time, resulting in a crystal structure with a planar quadrilateral configuration and neat and consistent arrangement. While improving the optical properties of the crystals, it expanded the application of tellurium-containing compounds in crystals.

[0016] 3. The tellurium-based optical crystal material with a 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

[0017] Figure 1 Tellurium-based optical crystal material (C 12 H8N2)TeCl2 three-dimensional framework structure; Figure 2 Tellurium-based optical crystal material (C 12 H8N2) X-ray powder diffraction pattern of TeCl2; Figure 3 Tellurium-based optical crystal material (C 12 H8N2)Thermogravimetric spectrum of TeCl2; Figure 4 Tellurium-based optical crystal material (C 12 H8N2)Infrared spectrum of TeCl2; Figure 5 Tellurium-based optical crystal material (C 12 H8N2)UV-visible diffuse reflectance spectrum of TeCl2; Figure 6 Tellurium-based optical crystal material (C 12 H8N2)Birefringence test chart of TeCl2. DETAILED DESCRIPTION

[0018] The specific implementation modes of the present invention are described in detail below with reference to the embodiments.

[0019] Example 1 A tellurium-based optical crystal material with a large birefringence is prepared by the following steps: 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 prepared by mixing hydrochloric acid and anhydrous ethanol in a volume ratio of 3:40; C12 The concentration of H8N2·H2O is 0.047 mol / L 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, and then cooled to room temperature at a rate of 5°C / hour to obtain light yellow flaky crystals, i.e., the primary product; S3: Rinse the primary product with anhydrous ethanol for 4 times.

[0020] Example 2 A tellurium-based optical crystal material with a large birefringence is prepared by the following steps: 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 prepared by mixing hydrochloric acid and anhydrous ethanol in a volume ratio of 3:40; C 12 The concentration of H8N2·H2O is 0.04 mol / L S2: The mixture was placed in the inner lining of a hydrothermal reactor, and the hydrothermal reactor was placed in a 160°C forced air drying oven and heated continuously for 6 days, and then cooled to room temperature at a rate of 5°C / hour to obtain light yellow flaky crystals, i.e., the primary product; S3: Rinse the primary product with anhydrous ethanol for 3 times.

[0021] Example 3 A tellurium-based optical crystal material with a large birefringence is prepared by the following steps: S1: C 12 H8N2·H2O and TeCl4 were dissolved in a mixed solvent and stirred for 25 min to obtain a mixture; wherein C 12 The molar ratio of H8N2·H2O to TeCl4 is 1:2.5; the mixed solvent is prepared by mixing hydrochloric acid and anhydrous ethanol in a volume ratio of 3:40; C 12 The concentration of H8N2·H2O is 0.05 mol / L S2: The mixture was placed into the inner lining of a hydrothermal reactor, and the hydrothermal reactor was placed in a 140°C forced air drying oven and heated continuously for 9 days, and then cooled to room temperature at a rate of 5°C / hour to obtain light yellow flaky crystals, i.e., the primary product; S3: Rinse the primary product with anhydrous ethanol for 5 times.

[0022] Experimental example The properties of the tellurium-based optical crystal materials prepared in Examples 1 to 3 are similar. The tellurium-based optical crystal material in Example 1 is taken as an example to illustrate its properties.

[0023] 1. Tellurium-based optical crystal materials with large birefringence (C 12 Structural Analysis of H8N2)TeCl2 Tellurium-based optical crystal materials (C 12 The crystallographic data of H8N2)TeCl2 are shown in Table 1.

[0024] Table 1 Tellurium-based optical crystal materials (C 12 Crystallographic data of H8N2)TeCl2 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 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 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. 12 The symmetric 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 two N atoms containing lone pairs of electrons on o-phenanthroline, and forms a covalent bond with two Cl atoms. The bond lengths of Te-Cl and Te-N 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 butterfly-shaped structure. Figure 1 The 0-dimensional cluster structure shown.

[0025] 2. Tellurium-based optical crystal materials with large birefringence (C 12 Characterization of H8N2)TeCl2 (1) Tellurium-based optical crystal materials (C 12 X-ray Powder Diffraction Analysis of H8N2)TeCl2 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.

[0026] (2) Tellurium-based optical crystal materials (C 12 Thermogravimetric analysis of H8N2)TeCl2 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 starts to lose weight at 135℃~700℃, with a total weight loss rate of 33%.

[0027] (3) Tellurium-based optical crystal materials (C 12 Infrared Spectrum Analysis of H8N2)TeCl2 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 window appears at 3100 cm -1 The peaks on the left and right are the stretching vibrations of the unsaturated CH bonds 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, at 701~808 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 indicates that o-phenanthroline and Te 2+ Coordination took place and a coordination bond was formed.

[0028] (4) Tellurium-based optical crystal materials (C 12 Analysis of UV-Vis Diffuse Reflectance Spectrum of H8N2)TeCl2 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 (H8N2)TeCl2 is 3.20 eV, and the corresponding UV absorption cutoff edge is 387.5 nm. 12 H8N2)TeCl2 is an ultraviolet optical material with application prospects.

[0029] (5) Tellurium-based optical crystal materials (C 12 Analysis of Birefringence of H8N2)TeCl2 The tellurium-based optical crystal material (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.

[0030] Although the specific implementation of the present invention is described in detail in conjunction with the embodiments, it should not be understood as limiting the scope of protection of this patent. Within the scope described in 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, 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.

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: 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; S2: react the mixture in a closed environment at 140-160°C for 6-9 days, then cool to room temperature, collect crystals, and obtain a primary product; S3: Wash the primary product.

3. The preparation method according to claim 2, characterized in that: The C 12 The molar ratio of H8N2·H2O and TeCl4 is 1:2.

5.

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

40.

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

6. The preparation method according to claim 2, characterized in that: In S2, the reaction temperature is 150°C and the reaction time is 7 days.

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

8. 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.

9. Use of the tellurium-based optical crystal material with a large birefringence as claimed in claim 1 in the preparation of polarization devices.

Images