Birefringent crystal material and preparation method and application thereof

Abstract

The invention relates to the technical field of artificial crystal materials, in particular to a birefringent crystal material and a preparation method and application thereof. The invention provides a novel birefringent crystal material which has a chemical formula of [C (NH2) 3] [ICl4] and has huge birefringence. The raw materials used in the preparation method of the birefringent crystal material are low in toxicity to human bodies, the crystal growth period is short, the cost is low, and the crystal purity is high; the birefringent crystal material can be used as a polarization optical device in the fields of optics and communication.

Description

Technical Field

[0001] The present invention relates to the technical field of artificial crystal materials, and particularly relates to a birefringent crystal material, a preparation method thereof, and an application thereof. Background Art

[0002] Birefringent crystal materials are the core media for regulating the polarization state of light waves in optoelectronic devices and are widely used in precision optical modulators, polarization sensors, and optical communication devices. Although inorganic birefringent materials have been commercialized, their inherent defects such as optical uniformity, processing difficulty, and environmental stability severely restrict their application prospects in optical devices. For example, natural calcite (CaCO3) has insufficient optical uniformity due to lattice defects; titanium dioxide (TiO2) has a high artificial synthesis cost and is difficult to process; the thermal expansion anisotropy of α-phase barium metaborate (α-BaB2O4) easily causes thermal stress mismatch problems in devices; the transmittance of yttrium vanadate (YVO4) drops sharply in the deep ultraviolet band; the birefringence of lithium niobate (LiNbO3) is difficult to meet the requirements of high-precision regulation.

[0003] With the development of the times, people's requirements for birefringent crystal materials are getting higher and higher. Therefore, the development of new birefringent crystal materials has become the key path to promoting the performance leap of optoelectronic devices. Summary of the Invention

[0004] The purpose of the present invention is to provide a birefringent crystal material, a preparation method thereof, and an application thereof to solve at least one technical problem existing in the prior art.

[0005] In the first aspect of the present invention, a birefringent crystal material is provided, and its chemical formula is [C(NH2)3][ICl4], belonging to the monoclinic system, and the space group is P 21 / c , the unit cell parameters are a = 14.96~15.78 Å, b = 3.99~4.00 Å, c = 15.00~15.75 Å, α = 90°, β = 95.10 ~ 95.18°, γ = 90°, V = 935.3~942.2 Å 3 , Z = 4.

[0006] The above birefringent crystal material contains [ICl4] - motifs, and the anisotropy of the polarizability of this motif reaches the maximum value among the four-coordinated structural motifs. Therefore, the above birefringent crystal material has a significantly higher birefringence.

[0007] Furthermore, the unit cell parameters of the above birefringent crystal material are a = 15.779(8) Å, b = 3.996(2) Å, c = 15.003(7) Å, α = 90°, β = 96.336°, γ = 90°, V = 942(8) Å 3 , Z = 4.

[0008] In the second aspect of the present invention, a preparation method of the above birefringent crystal material is provided, which includes the following steps: Dissolve guanidine hydrochloride (CN3H6Cl) and iodine pentoxide (I2O5) in an acidic solution to obtain a mixed solution; Stir the above mixed solution, remove the viscous substance formed at the bottom of the above mixed solution, continue stirring until the above mixed solution is clear, and let it stand for crystallization to obtain the above birefringent crystal material.

[0009] Furthermore, the molar ratio of the above guanidine hydrochloride to iodine pentoxide can be 6 - 8:1.

[0010] Furthermore, the above acidic solution can be hydrochloric acid solution, sulfuric acid solution, nitric acid solution or phosphoric acid solution.

[0011] Furthermore, the concentration range of the above acidic solution can be 3 - 6 mol / L.

[0012] Furthermore, the time for the above static crystallization can be 6 - 15 days.

[0013] In the third aspect of the present invention, the application of the above birefringent crystal material in the preparation of polarization optical devices is provided.

[0014] In the fourth aspect of the present invention, a polarization optical device is provided, which includes a birefringent crystal formed by the above birefringent crystal material.

[0015] Furthermore, the above polarization optical device is a polarization sensor, a wide - spectrum device or a polarization beam splitter.

[0016] Furthermore, the above polarization optical device is an optical isolator.

[0017] The technical solution of the embodiment of the present invention has the following beneficial effects: A new birefringent crystal material is provided, which has a large birefringence; the raw materials used in the preparation method of the birefringent crystal material are less toxic to the human body, the crystal growth period is short, the cost is low, and the crystal purity is high; the birefringent crystal material can be used as a polarization optical device and find applications in the fields of optics and communication. Description of the Drawings

[0018] Figure 1 It is a schematic diagram of the crystal structure of the birefringent crystal material in the embodiment of the present invention.

[0019] Figure 2 These are the X-ray diffraction patterns of the birefringent crystal material in the embodiments of the present invention and the X-ray diffraction patterns simulated based on the crystal structure of [C(NH2)3][ICl4].

[0020] Figure 3 This is the ultraviolet transmission spectrum of the birefringent crystal material in the embodiments of the present invention.

[0021] Figure 4 These are the refractive index and birefringence of the theoretically calculated birefringent crystal material at different wavelengths in the embodiments of the present invention.

[0022] Figure 5 This is a schematic diagram of the working principle of the polarization optical device in the embodiments of the present invention. Detailed implementation manners

[0023] Next, in combination with the embodiments of the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0024] Samples 1# to 6# of the birefringent crystal material were prepared by the aqueous solution method. The steps are as follows: In a beaker, guanidine hydrochloride, iodine pentoxide, and an acidic solution were mixed in a certain proportion to obtain a mixed solution; the mixed solution was stirred, the viscous substance formed at the bottom was filtered, and stirring was continued until the solution was clear. The opening was sealed with plastic wrap, and holes were made in the plastic wrap. After standing at room temperature for a period of time, yellow rod-shaped crystals grew at the bottom of the mixed solution, which is the birefringent crystal material.

[0025] The relationship between the types and ratios of raw materials in the initial mixture, the concentration and volume of the acidic solution, the crystallization time, and the sample numbers is shown in Table 1.

[0026] Table 1 Correspondence between samples of each embodiment and raw materials used and synthesis conditions

[0027] The single-crystal X-ray diffraction and powder X-ray diffraction methods were used to perform structural analysis and purity analysis on Samples 1# to 6# respectively. The tests were carried out on an Agilent SuperNova single-crystal diffractometer equipped with a molybdenum target (λ = 0.71073 Å), and the diffraction data of the single crystals were collected under the condition of 293(2) K. After the data collection was completed, the collected single-crystal data were processed using OLEX2 software; through the SHELXTL program suite, the crystal structure was refined using the full-matrix least-squares technique, and the crystal structure was analyzed and refined; finally, the PLATON software was used to check whether the single-crystal structure had higher symmetry, and the crystal structure was finally obtained. The results of single-crystal X-ray diffraction showed that Samples 1# to 6# had the same chemical structural formula and crystal structure, the chemical formula was [C(NH2)3][ICl4], and the molecular weight was 328.79; it belonged to the monoclinic system, and the space group was P 21 / c , the unit cell parameters were a = 14.96~15.78 Å, b = 3.99~4.00 Å, c = 15.00~15.75 Å, α = 90°, β = 95.10 ~ 95.18°, γ = 90°, V = 935.3~942.2 Å 3 , Z = 4.

[0028] Taking Sample 1# as a typical representative, its crystallographic parameters were that the unit cell parameters were a = 15.779(8) Å, b = 3.996(2) Å, c = 15.003(7) Å, α = 90°, β = 96.336°, γ = 90°, V = 942(8) Å 3 , Z = 4. The crystal structure of Sample 1# was as shown in Figure 1 .

[0029] The powder X-ray diffraction test was carried out using a Miniflex600 type powder X-ray diffractometer (λ = 1.5418 Å). The diffraction angle range was set to 5°~75°, the step width was 0.02°, and the rate was 0.01° s⁻¹ for the test. The results of the powder X-ray diffraction test showed that on the X-ray diffraction patterns of Samples 1# to 6#, the peak positions of each sample were the same, and the peak intensities were slightly different. Taking Sample 1# as a typical representative, as shown in Figure 2 , according to the crystal structure analyzed by its single-crystal X-ray diffraction, the peak positions of the fitted X-ray diffraction pattern were completely consistent with those of the X-ray diffraction pattern measured after Sample 1# was ground into powder, and there were slight differences in the peak intensities. This indicated that the obtained samples had high purity.

[0030] The diffuse reflection spectrum test of Sample 1# was carried out on a PerkinElmer Lamda-950 ultraviolet / visible / near-infrared spectrophotometer. The specific measurement process is as follows: First, BaSO4 was used as a standard sample (100% reflectivity) to scan the baseline once. Then, the pure Sample 1# powder was evenly sprinkled on the surface of BaSO4, compacted with a quartz column, and then tested. The information on the diffuse reflection characteristics of Sample 1# within 200 - 800 nm was recorded. The results are as Figure 3 shown. The diffuse reflection spectrum of Sample 1# shows that its absorption cut-off edge is approximately around 243 nm. Based on the Kubelka-Munk function, the reflectivity can be used to calculate the experimental energy gap: F(R)=(1 - R) 2 / (2R)=K / S where R is the reflectivity, K is the absorption, and S is the scattering. According to the above formula, the experimental band gap of Sample 1# can be calculated to be 2.34 eV.

[0031] The first-principles calculations of the optical properties of Samples 1# - 6# were carried out based on density functional theory. The calculation of the refractive index shows obvious anisotropy. As Figure 4 shown, the birefringence reaches 0.95 at a wavelength of 550 nm.

[0032] Samples 1# - 6# can all be used to prepare polarization optical devices. The polarization optical device is an optical isolator. As Figure 5 shown, the optical isolator core of the optical isolator includes a first birefringent crystal 2, a rotator 3, and a second birefringent crystal 4. Among them, both the first birefringent crystal 2 and the second birefringent crystal 4 are formed of the birefringent crystal material [C(NH2)3][ICl4]. When the optical isolator is placed in the optical path, a light beam is emitted by a laser emitter 1, passes through the first birefringent crystal 2, is divided into an e-ray and an o-ray, and then enters the second birefringent crystal 4 through the rotator 3. The generated output light beam is collected by a collimator 5 to collect the optical signal.

[0033] As described above, only the preferred embodiments of the present invention are provided, and there is no limitation in any form and substance to the present invention. It should be noted that for those of ordinary skill in the art in this technical field, without departing from the method of the present invention, several improvements and supplements can still be made, and these improvements and supplements should also be regarded as the protection scope of the present invention. For those skilled in the art, without departing from the spirit and scope of the present invention, any equivalent changes made by using the above-disclosed technical content, such as slight modifications, decorations, and evolutions, are equivalent embodiments of the present invention; at the same time, any equivalent changes, modifications, and evolutions made to the above embodiments based on the essential technology of the present invention still fall within the scope of the technical solutions of the present invention.

Claims

1. A birefringent crystal material, characterized in that, The chemical formula is [C(NH2)3][ICl4], belonging to the monoclinic system, and the space group is P 21 / c , the unit cell parameters are a = 14.96~15.78 Å, b = 3.99~4.00 Å, c = 15.00~15.75 Å, α = 90°, β = 95.10 ~ 95.18°, γ = 90°, V = 935.3~942.2 Å 3 , Z = 4.

2. The preparation method of the birefringent crystal material according to claim 1, characterized in that, It includes the following steps: Dissolve guanidine hydrochloride and iodine pentoxide in an acidic solution to obtain a mixed solution; Stir the mixed solution, remove the viscous substance formed at the bottom of the mixed solution, continue stirring until the mixed solution is clarified, and let it stand for crystallization to obtain the birefringent crystal material.

3. The method according to claim 2, wherein The molar ratio of guanidine hydrochloride to iodine pentoxide is 6 - 8:

1.

4. The method according to claim 2, wherein The acidic solution is hydrochloric acid solution, sulfuric acid solution, nitric acid solution or phosphoric acid solution.

5. The method according to claim 2, characterized in that, The concentration range of the acidic solution is 3 - 6 mol / L.

6. The method according to claim 2, characterized in that The time for standing crystallization is 6 - 15 days.

7. Use of the birefringent crystal material according to claim 1 in the preparation of a polarization optical device.

8. A polarization optical device, characterized in that, It includes a birefringent crystal formed by the birefringent crystal material according to claim 1.

9. The polarization optical device according to claim 8, wherein The polarization optical device is a polarization sensor, a wide-spectrum device or a polarization beam splitter.

10. The polarization optical device according to claim 8, characterized in that, The polarization optical device is an optical isolator.

Images