Bi8o6(oH)4(so4)(no3)6.h2o compound, crystal thereof, preparation method and application

Abstract

The application discloses a Bi8O6(OH)4(SO4)(NO3)6.H2O compound, a crystal thereof, a preparation method and application in nonlinear optics. 10 The crystal has a zero-dimensional crystal structure composed of a unique [Bi8O ‑ (SO4)] closed polar cage and a free [NO3] 2‑ Group introduces a Bi-O cage to form a unique polar closed cage, and presents a polarization superposition enhancement effect, so that the crystal has a strong frequency doubling effect, and has potential application in an ultraviolet to near-infrared region; meanwhile, the crystal is non-hygroscopic, stable in air, and has good physical properties.

Description

Technical Field

[0001] This invention belongs to the field of functional crystal materials technology, specifically relating to a Bi8O6(OH)4(SO4)(NO3)6·H2O compound, its crystal, preparation method, and application in nonlinear optics. Background Technology

[0002] Nonlinear optical crystals have wide applications in industry, civilian use, and medicine. Research on nonlinear optical crystals has always been a hot topic in the field of optoelectronic functional crystals. Relying on their frequency conversion performance, they can easily convert mature lasers to other wavelengths, thereby expanding the laser wavelength range and meeting the application needs of different fields. With the continuous development of laser technology, the performance requirements for nonlinear optical crystals are also constantly increasing, making the exploration of novel nonlinear optical crystals increasingly challenging. The anionic group theory plays an important guiding role in the exploration of nonlinear optical crystals. From the perspective of compound systems and functional units, most previous developments of nonlinear optical crystals mainly originated from borates, phosphates, sulfates, etc., which possess planar triangular π-conjugation (BO3). 3- Groups and tetrahedrons (BO4) 5- (PO4) 3- and (SO4) 2- Traditional single-component systems with the same functional groups are no longer viable alternatives. Currently, the strategy of functional motif compositing, which involves introducing two or more anionic functional motifs into the same crystal, has proven to be an effective approach for developing novel nonlinear optical crystals. However, synthesizing compounds with composite functional motifs often presents significant challenges. Summary of the Invention

[0003] Based on the above background, the present invention provides a compound with the chemical formula Bi8O6(OH)4(SO4)(NO3)6·H2O.

[0004] The present invention also provides a method for preparing the compound with the chemical formula Bi8O6(OH)4(SO4)(NO3)6·H2O, the method comprising: mixing a compound containing Bi, a compound containing S and a compound containing N, and subjecting the mixture to a hydrothermal reaction to prepare the compound with the chemical formula Bi8O6(OH)4(SO4)(NO3)6·H2O.

[0005] According to an embodiment of the present invention, the Bi-containing compound is selected from at least one of Bi2O3, BiF3, Bi(NO3)3·5H2O and BiI3, preferably Bi(NO3)3·5H2O.

[0006] According to an embodiment of the present invention, the S-containing compound is selected from at least one of H2SO4, (NH4)2SO4, K2SO4 and CaSO4, preferably H2SO4.

[0007] According to an embodiment of the present invention, the nitrogen-containing compound is selected from at least one of LiNO3, NaNO3, KNO3, Ba(NO3)2, and Bi(NO3)3·5H2O, preferably Bi(NO3)3·5H2O. When both the Bi-containing compound and the nitrogen-containing compound are selected from Bi(NO3)3·5H2O, the amount added is calculated according to the stoichiometric ratio in the chemical formula, or the amount added is determined according to the following proportions.

[0008] According to an embodiment of the present invention, in the compounds containing Bi, S, and N, the molar ratio of Bi, S, and N, n(Bi):n(S):n(N), is (5-20):(1-2):(15-60); preferably (8-16):(1-2):(24-48); exemplary ratios are 8:1:24, 15:2:45, and 10:1:30.

[0009] According to an embodiment of the present invention, the hydrothermal reaction is carried out in a solvent, which may be selected from organic solvents or inorganic solvents, preferably inorganic solvents, such as a mixture of water and sulfuric acid, exemplified by a deionized aqueous solution of sulfuric acid.

[0010] According to an embodiment of the present invention, the total mass of the raw materials (i.e., the sum of the masses of the compounds containing Bi, S, and N) to the volume ratio of the solvent can be (60-150) g:100 mL, preferably (70-100) g:100 mL; exemplary examples are 75 g:100 mL, 85 g:100 mL, and 95 g:100 mL.

[0011] According to an embodiment of the present invention, the reaction temperature of the hydrothermal reaction can be 160–220°C, preferably 180–220°C, for example, 180°C, 200°C, or 220°C. Further, the heating rate of the hydrothermal reaction can be 10–30°C / h, for example, 10°C / h, 20°C / h, or 30°C / h.

[0012] According to an embodiment of the present invention, the reaction time of the hydrothermal reaction can be 1 to 3 days, preferably 1 to 2 days, with 1 day and 2 days being exemplary.

[0013] According to an embodiment of the present invention, the preparation method further includes: after the hydrothermal reaction is completed, collecting the compound with the chemical formula Bi8O6(OH)4(SO4)(NO3)6·H2O from the reaction solution.

[0014] The present invention also provides a nonlinear optical crystal with the chemical structural formula Bi8O6(OH)4(SO4)(NO3)6·H2O, that is, the nonlinear optical crystal is a Bi8O6(OH)4(SO4)(NO3)6·H2O crystal.

[0015] According to an embodiment of the present invention, the nonlinear optical crystal belongs to an orthorhombic crystal system with space group Pmn21; the cell parameters are as follows: α=β=γ=90°, z=8.

[0016] According to an embodiment of the present invention, the nonlinear optical crystal does not have a center of symmetry.

[0017] According to an embodiment of the present invention, the nonlinear optical crystal has the following characteristics: Figure 1 The crystal structure shown is composed of [Bi8O] 10 [SO4] Closed polar cage and free [NO3] - The zero-dimensional crystal structure formed.

[0018] According to an embodiment of the present invention, the nonlinear optical crystal has the following characteristics: Figure 2 The X-ray diffraction pattern shown.

[0019] According to an embodiment of the present invention, the ultraviolet absorption edge of the nonlinear optical crystal can reach 265 nm, the band gap is 4.09 eV, and a high transmittance can be achieved between 0.3 and 2.0 μm.

[0020] The present invention also provides a method for preparing the nonlinear optical crystal, characterized in that the method includes: mixing a compound containing Bi, a compound containing S, a compound containing N and a solvent, and then heating and crystallizing to obtain the nonlinear optical crystal.

[0021] According to an embodiment of the present invention, the selection of the Bi-containing compound, the S-containing compound, the N-containing compound, and the solvent is consistent with the selection in the preparation method of the compound with the chemical formula Bi8O6(OH)4(SO4)(NO3)6·H2O.

[0022] According to an embodiment of the present invention, the temperature for the heating crystallization is 160–240°C, preferably 180–220°C;

[0023] The heating and crystallization time is 5 to 15 days, preferably 5 to 12 days, with examples being 5 days, 7 days, 10 days, and 15 days.

[0024] According to an embodiment of the present invention, the preparation method further includes: after crystallization is completed, cooling, separating, and drying the reaction solution to obtain the nonlinear optical crystal.

[0025] According to an embodiment of the present invention, during the cooling process, the cooling rate is 1 to 20°C / h, specifically 1 to 10°C / h, and exemplary values ​​are 1°C / h, 5°C / h, and 9°C / h.

[0026] According to an embodiment of the present invention, the method for preparing the nonlinear optical crystal specifically includes the following steps:

[0027] (1) Mix the Bi-containing compound, the S-containing compound, the N-containing compound and the solvent, and then heat the mixture to 160-240℃ at a rate of 10-30℃ / hour for 5-15 days to crystallize.

[0028] (2) After crystallization, the reaction system is cooled to room temperature at a rate of 1-20℃ / h, and the nonlinear optical crystal is obtained after separation and drying.

[0029] The present invention also provides applications of the aforementioned nonlinear optical crystal in optical devices. For example, it can be used in fields such as laser frequency conversion, electro-optic modulation, photorefractive information processing, or information storage.

[0030] Preferably, it is used as a frequency doubling device in an all-solid-state laser.

[0031] Preferably, it is used for frequency doubling light output of 1-2 micrometer lasers.

[0032] According to an embodiment of the present invention, the nonlinear optical crystal can be used as an optical device in the ultraviolet-near infrared optical band.

[0033] According to an embodiment of the present invention, the nonlinear optical crystal is used in the fields of fabricating frequency multiplier generators, up or down frequency converters, or optical parametric oscillators.

[0034] The beneficial effects of this invention are:

[0035] The inventors discovered that in the nitrate system, π-conjugated (NO3) - Planar triangular groups possess a wide band gap and a large microscopic second-order polarizability. Their coplanar and consistent arrangement is beneficial for synthesizing nonlinear optical crystals with both large band gaps and frequency doubling coefficients. (NO3) - The group is considered one of the most excellent nonlinear optically active groups. In the sulfate system, (SO4) 2- The (NO3) group is also a potentially nonlinear optically active group and is often used to synthesize nonlinear optical crystals with large band gaps. Based on this, this invention constructs a group containing (NO3) - and (SO4) 2-Compounds containing these two nonlinear optically active groups and their nonlinear optical crystals. Specifically, they possess the following characteristics:

[0036] (1) This invention provides a novel compound of nitric acid and sulfuric acid, Bi8O6(OH)4(SO4)(NO3)6·H2O, and its crystals. The Bi8O6(OH)4(SO4)(NO3)6·H2O crystals crystallize in the non-centrosymmetric space group Pmn21, and their structure consists of a unique [Bi8O 10 [SO4] Closed polar cage and free [NO3] - The resulting zero-dimensional crystal structure is (SO4). 2- The introduction of functional groups into the Bi-O cage forms a unique polar closed cage, exhibiting a polarization superposition enhancement effect, which gives the crystal a strong frequency doubling effect and potential applications in the ultraviolet to near-infrared region. Simultaneously, this crystal is non-hygroscopic, stable in air, and possesses excellent physical properties.

[0037] (2) The Bi8O6(OH)4(SO4)(NO3)6·H2O crystal of the present invention outputs strong 532nm light under 1064nm laser irradiation, and its powder frequency doubling effect is about 12 times that of α-SiO2.

[0038] (3) The Bi8O6(OH)4(SO4)(NO3)6·H2O crystal of the present invention has a wide light transmission range and its ultraviolet absorption cutoff wavelength can reach 265nm. It can be applied in the ultraviolet-near infrared region and has potential application prospects in the fields of laser frequency conversion, electro-optic modulation, photorefractive information processing and information storage.

[0039] (4) The Bi8O6(OH)4(SO4)(NO3)6·H2O crystal of the present invention has stable physicochemical properties.

[0040] (5) The preparation method of Bi8O6(OH)4(SO4)(NO3)6·H2O compound and crystal of the present invention is simple, fast in growth and low in cost. Attached Figure Description

[0041] Figure 1 This is a schematic diagram of the crystal structure of Bi8O6(OH)4(SO4)(NO3)6·H2O crystal of the present invention.

[0042] Figure 2 The image shows a comparison between the X-ray diffraction pattern obtained by fitting the crystal structure of Example 2 and the X-ray diffraction pattern of the powder sample of Example 1.

[0043] Figure 3This is a schematic diagram of a frequency doubling test, where 1 is a laser, 2 is the incident laser beam, 3 is the Bi8O6(OH)4(SO4)(NO3)6·H2O crystal prepared in Example 3, 4 is the generated outgoing laser beam, and 5 is a photomultiplier tube equipped with a filter.

[0044] Figure 4 The results of frequency doubling test are for the Bi8O6(OH)4(SO4)(NO3)6·H2O crystal sample prepared in Example 2.

[0045] Figure 5 The image shows the UV-Vis-NIR diffuse reflectance of the Bi8O6(OH)4(SO4)(NO3)6·H2O crystal sample prepared in Example 2.

[0046] Figure 6 The infrared spectrum of the Bi8O6(OH)4(SO4)(NO3)6·H2O crystal sample prepared in Example 2 is shown. Detailed Implementation

[0047] The technical solution of the present invention will be further described in detail below with reference to specific embodiments. It should be understood that the following embodiments are merely illustrative and explanatory of the present invention, and should not be construed as limiting the scope of protection of the present invention. All technologies implemented based on the above content of the present invention are covered within the scope of protection intended by the present invention.

[0048] Unless otherwise stated, the raw materials and reagents used in the following examples are commercially available products or can be prepared by known methods.

[0049] Example 1

[0050] Preparation of Bi8O6(OH)4(SO4)(NO3)6·H2O compounds

[0051] The Bi8O6(OH)4(SO4)(NO3)6·H2O compound was prepared by the following steps:

[0052] (a) Bi(NO3)3·5H2O (0.015mol, 7.276g), H2O (8mL), and H2SO4 solution (0.1mL, concentration 98%) were placed in a reaction vessel with a polytetrafluoroethylene liner (25mL), and the temperature was increased to 180℃ at a rate of 20℃ / h and kept at the temperature for 2 days.

[0053] (b) After the reaction is complete, the system is naturally cooled to room temperature. After separation and drying, Bi8O6(OH)4(SO4)(NO3)6·H2O compound powder can be obtained.

[0054] Example 2

[0055] Preparation of Bi8O6(OH)4(SO4)(NO3)6·H2O crystals

[0056] Bi8O6(OH)4(SO4)(NO3)6·H2O crystals were prepared by the following steps:

[0057] (a) Bi(NO3)3·5H2O (0.15mol, 72.76g), H2O (80mL) and H2SO4 solution (1mL, concentration 98%) were placed in a reaction vessel with a polytetrafluoroethylene liner (250mL), and the temperature was increased to 180℃ at a rate of 15℃ / h and crystallized at a constant temperature for 7 days.

[0058] (b) After crystallization, the reaction system is cooled to room temperature at a rate of 5℃ / h. After separation and drying, Bi8O6(OH)4(SO4)(NO3)6·H2O crystals can be obtained.

[0059] A schematic diagram of the structure of the Bi8O6(OH)4(SO4)(NO3)6·H2O crystal obtained in this embodiment is shown below. Figure 1 As shown, this crystal belongs to the orthorhombic crystal system, with space group Pmn21 and cell parameters of [missing information]. α=β=γ=90°, z=8.

[0060] Example 3

[0061] Preparation of Bi8O6(OH)4(SO4)(NO3)6·H2O crystals

[0062] Bi8O6(OH)4(SO4)(NO3)6·H2O crystals were prepared by the following steps:

[0063] (a) Bi(NO3)3·5H2O (0.015mol, 7.276g), H2O (8mL) and H2SO4 solution (0.1mL, concentration 98%) were placed in a reaction vessel with a polytetrafluoroethylene liner (25mL), and the temperature was increased to 200℃ at a rate of 20℃ / h and kept at the temperature for 10 days for crystallization.

[0064] (b) After crystallization, the reaction system is naturally cooled to room temperature, and Bi8O6(OH)4(SO4)(NO3)6·H2O crystals are obtained after separation and drying.

[0065] Example 4

[0066] Structural analysis and phase analysis of Bi8O6(OH)4(SO4)(NO3)6·H2O crystal

[0067] The structure of the Bi8O6(OH)4(SO4)(NO3)6·H2O crystal samples prepared in Examples 2 and 3 was analyzed by single-crystal X-ray diffraction. The crystal structure of Bi8O6(OH)4(SO4)(NO3)6·H2O was determined using a Bruker SMARTAPEX III CCD diffractometer under Mo Kα radiation. Recording was performed at 293(2)K, with a scanning mode of ω=2θ. Data were processed using the Multi-Scan method for absorption correction. Structural analysis was performed using the SHELXTL package; the positions of heavy atoms were determined using the direct method, and the coordinates of the remaining atoms were obtained using the difference Fourier synthesis method; F-based... 2 The coordinates of all atoms and anisotropic thermal parameters were refined using the full matrix least squares method. Single-crystal X-ray diffraction results showed that the chemical formula of the crystals prepared in Examples 2 and 3 was Bi8O6(OH)4(SO4)(NO3)6·H2O.

[0068] The phases obtained in Example 1 were analyzed using powder X-ray diffraction (XRD). Powder XRD data for Bi8O6(OH)4(SO4)(NO3)6·H2O were acquired in the range of 5°–80° (2θ) with a step width of 0.02° and a step size of 2s on a SmartLab 9KW powder XRD instrument with Cu-Kα radiation. The powder XRD patterns showed that the diffraction peak positions of the samples in Examples 1–3 were basically the same. Figure 2 As shown, the X-ray diffraction pattern obtained by fitting the crystal structure of Example 2 is basically consistent with the peak position and intensity of the X-ray diffraction pattern of the sample powder of Example 1. This indicates that the Bi8O6(OH)4(SO4)(NO3)6·H2O single crystal prepared in Example 2 of the present invention is a single pure phase with high purity.

[0069] Example 5

[0070] Frequency doubling test experiment of Bi8O6(OH)4(SO4)(NO3)6·H2O crystal

[0071] The Bi8O6(OH)4(SO4)(NO3)6·H2O crystal sample obtained in Example 2 was subjected to frequency doubling tests, such as... Figure 3 As shown. A 1064nm laser emitted from an Nd:YAG solid-state laser was used as the fundamental frequency light to irradiate the Bi8O6(OH)4(SO4)(NO3)6·H2O crystal powder prepared in Example 2. The generated frequency-doubled light was detected using a photomultiplier tube, and the harmonic intensity was displayed using an oscilloscope. The specific method is as follows:

[0072] The particle size distribution of the crystal samples to be tested was determined using standard sieves to be 45–58 μm, 58–75 μm, 75–106 μm, 106–150 μm, 150–250 μm, and 250–355 μm. The crystal samples of these particle sizes were then placed... Figure 3 At position 3 of the apparatus shown, at room temperature, a Q-switched Nd:YAG laser (i.e., laser 1) is used as the input light source. The incident wavelength of the laser beam 2 is 1064 nm. After the incident laser beam 2 passes through crystal 3 of Example 2, the frequency harmonic signal of the output laser beam 4 after passing through filter 5 is measured, and the trend of the frequency harmonic signal with particle size is observed to determine whether phase matching can be achieved. Under the same test conditions, α-SiO2 is used as the reference for the second harmonic test. The test results are as follows. Figure 4 As shown in the figure, the results indicate that Bi8O6(OH)4(SO4)(NO3)6·H2O crystals (i.e. Figure 4 The frequency doubling effect of BSNO under 1064nm laser irradiation is about 12 times that of α-SiO2 under the same conditions.

[0073] Example 6

[0074] Spectral performance testing of Bi8O6(OH)4(SO4)(NO3)6·H2O crystals

[0075] Taking the Bi8O6(OH)4(SO4)(NO3)6·H2O crystal sample obtained in Example 1 as an example, ultraviolet diffuse reflectance spectra of Bi8O6(OH)4(SO4)(NO3)6·H2O were measured on a Shimadzu SolidSpec-3700DUV spectrophotometer. The spectra of Bi8O6(OH)4(SO4)(NO3)6·H2O in the range of 500–4000 cm⁻¹ were recorded using a Nicolet iS50 FT-IR spectrometer. -1 The infrared spectrum was measured within the specified range. Diffuse reflectance testing used BaSO4 as a reference substrate for baseline measurement. Then, the Bi8O6(OH)4(SO4)(NO3)6·H2O crystal sample prepared in Example 2 was ground into powder and spread on BaSO4 for reflectance spectroscopy testing. Figure 5 and Figure 6 The figures show the UV-Vis-NIR diffuse reflectance and infrared spectra of the Bi8O6(OH)4(SO4)(NO3)6·H2O crystal sample prepared in Example 2. The results indicate that the Bi8O6(OH)4(SO4)(NO3)6·H2O prepared in this invention has a wide transmittance range, and its UV absorption cutoff wavelength can reach 265 nm. Further UV spectral conversion shows that the Bi8O6(OH)4(SO4)(NO3)6·H2O crystal prepared in this invention has a large band gap of approximately 4.09 eV.

[0076] The embodiments of the present invention have been described above by way of example. However, the scope of protection of the present invention is not limited to the above embodiments. Any modifications, equivalent substitutions, improvements, etc., made by those skilled in the art within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A nonlinear optical crystal, characterized by, The chemical structural formula of the crystal is Bi8O6(OH)4(SO4)(NO3)6·H2O, that is, the nonlinear optical crystal is Bi8O6(OH)4(SO4)(NO3)6·H2O crystal.

2. The nonlinear optical crystal of claim 1, wherein, The nonlinear optical crystal belongs to an orthorhombic system, a space group is Pmn21; a unit cell parameter is a=9.5438 , b=10.1242 , c=14.4298 , α=β=γ=90 o , z=8.

3. The nonlinear optical crystal of claim 1, wherein The nonlinear optical crystal does not have a symmetry center.

4. The nonlinear optical crystal of claim 1, wherein, The nonlinear optical crystal consists of [Bi8O 10 (SO4)] closed polar cage and free [NO3] - zero-dimensional crystal structure.

5. The method of producing a nonlinear optical crystal according to any one of claims 1 to 4, characterized by, The method comprises: mixing a Bi element-containing compound, an S element-containing compound, an N element-containing compound and a solvent, and then heating and crystallizing to obtain the nonlinear optical crystal. The Bi element-containing compound is at least one selected from Bi2O3, BiF3, Bi(NO3)3·5H2O and BiI3; The S element-containing compound is at least one selected from H2SO4, (NH4)2SO4, K2SO4 and CaSO4; The N element-containing compound is at least one selected from LiNO3, NaNO3, KNO3, Ba(NO3)2 and Bi(NO3)3·5H2O; The molar ratio of Bi, S and N in the Bi element-containing compound, the S element-containing compound and the N element-containing compound is n(Bi):n(S):n(N)=(5-20):(1-2):(15-60); The temperature of the heating and crystallizing is 160-240 DEG C; And / or, the time of the heating and crystallizing is 5-15 days.

6. Use of the nonlinear optical crystal according to any one of claims 1-4 in an optical device.

7. Use according to claim 6, characterized in that, It can be used in the fields of laser frequency conversion, electro-optic modulation, photorefractive information processing or information storage.

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