A nonlinear optical crystal, sodium lead aminosulfonate, its preparation method and uses

Abstract

This invention discloses a nonlinear optical crystal, sodium lead aminosulfonate, its preparation method, and its uses. The sodium lead aminosulfonate has the chemical formula Na₂Pb(SO₃NH₂)₄, belongs to the orthorhombic crystal system, space group C₂₂₁, has a molecular weight of 637.524, and unit cell parameters a = 9.8213(4) Å, b = 9.8315(4) Å, c = 14.5136(6) Å, α = 90°, β = 90°, and γ = 90°. The nonlinear optical crystal prepared by this invention exhibits good ultraviolet transmittance, low toxicity, stability, simple processing, and low cost.

Description

Technical Field

[0001] This invention belongs to the field of novel optoelectronic functional materials, and particularly relates to a nonlinear optical crystal, sodium lead aminosulfonate, its preparation method, and its uses. Background Technology

[0002] Since the advent of lasers, researchers have conducted extensive studies on their properties, discovering that lasers possess a series of characteristics such as high energy, single wavelength, and directional propagation, enabling their wide application in fields such as medicine, scientific research, industrial manufacturing, and aerospace. Depending on the working medium, lasers can be classified into solid-state lasers, gas lasers, dye lasers, semiconductor lasers, etc. Among them, solid-state lasers have advantages such as small size, long lifespan, and high beam quality, making them widely popular in practical applications. Limited by the energy level structure of rare-earth activated ions in the working medium, the most widely used laser wavelengths are mainly distributed in the infrared to near-infrared region. In 1961, Franken et al. experimentally demonstrated the laser frequency doubling phenomenon, where the frequency of the laser light passing through the medium doubles that of the incident light. This phenomenon brought nonlinear optical effects into the public eye. Subsequent research found that nonlinear optical phenomena can not only double the laser frequency but also extend the laser to other wavelength bands through sum-frequency and difference-frequency methods. Utilizing nonlinear optical effects, the application wavelength range of solid-state lasers has been significantly expanded, and nonlinear optical materials have become a hot research area for researchers worldwide.

[0003] As our understanding of crystal growth methods has deepened, significant progress has been made in the research of nonlinear optical crystal materials over the past half-century. Not only have major achievements been made in the discovery of new materials, but many of these materials have also been successfully applied in the field of lasers.

[0004] Currently, common nonlinear optical crystals can be broadly classified into two categories from a chemical perspective: inorganic nonlinear optical crystals and organic nonlinear optical crystals. Inorganic nonlinear optical crystal materials represent the starting point for the exploration of nonlinear optical crystal materials and were the first type of nonlinear optical crystal materials to be put into practical application, playing a dominant role in the practical research of second-order nonlinear optical materials. Based on the transmission band and applicable laser wavelength range, inorganic nonlinear optical crystal materials can be further divided into deep ultraviolet nonlinear optical crystals, ultraviolet nonlinear optical crystals, visible-near-infrared nonlinear optical crystals, and mid-far-infrared nonlinear optical crystals.

[0005] Ultraviolet and deep ultraviolet light, due to their short wavelengths, high photon energy, and excellent beam focusing performance, have shown significant application value in high-resolution imaging, photoelectron spectroscopy analysis, photolithography, and optical disc reading, and are one of the most important development directions in the international optoelectronic field. From the late 1970s to the 1980s, scientists successively discovered a series of ultraviolet and deep ultraviolet nonlinear optical crystals with excellent performance, such as β-BBO (barium β-metabolicate), LBO (lithium borate), CLBO (lithium cesium borate), and KBBF (potassium beryllium fluoroborate). Most of these crystals have been commercialized, but there are still obvious defects: (1) KBBF contains highly toxic Be, making crystal growth difficult and costly; (2) Some borate systems require high-temperature solid-state synthesis, which is complex and energy-intensive; (3) Traditional aminosulfonate crystal systems generally suffer from weak frequency doubling effect, insufficient stability, and harsh preparation conditions, making it difficult to balance low cost and practical performance. Summary of the Invention

[0006] The purpose of this invention is to provide a nonlinear optical crystal, sodium lead aminosulfonate, which has a narrow ultraviolet cutoff edge, good environmental stability, mild preparation method, and low toxicity, and can meet the requirements of nonlinear optical devices in the ultraviolet-visible light band.

[0007] To achieve the above objectives, the present invention provides a nonlinear optical crystal sodium lead sulfamate, with the chemical formula Na2Pb(SO3NH2)4, belonging to the orthorhombic crystal system, space group C2221, molecular weight 637.524, and unit cell parameters a=9.8213(4) Å, b=9.8315(4) Å, c=14.5136(6) Å, α=90°, β=90°, γ=90°.

[0008] The frequency doubling efficiency of the crystal powder is 0.3 times that of KH2PO4 (KDP), and the crystal is a transparent crystal with an ultraviolet cutoff edge of 258 nm.

[0009] A method for preparing a nonlinear optical crystal, sodium lead aminosulfonate, comprising: S1. Add sodium source, lead source and aminosulfonic acid to a beaker, then add deionized water and stir to react; S2. Continue to add deionized water to the solution after the reaction to adjust the pH of the solution, and obtain a mixed solution; S3. The mixed solution of S2 is reacted and crystallized in a constant temperature water bath using an aqueous solution method. After filtration, washing, and drying, a transparent crystal of the compound is obtained, which is the nonlinear optical crystal sodium lead aminosulfonate.

[0010] The molar ratio of the sodium source, lead source, and aminosulfonic acid is 3:4:14.

[0011] The sodium source is sodium carbonate or sodium hydroxide.

[0012] The lead source is lead carbonate or lead acetate.

[0013] The steps of the aqueous solution method include: transferring the clear mixed solution into a constant temperature water bath, sealing the mouth of the beaker with a sealing film, punching several small holes in the film, and placing the solution in a clean, uncontaminated environment with no air convection.

[0014] In step S3, the temperature of the constant temperature water bath is 30 ℃-40 ℃, the crystallization temperature is 30 ℃-40 ℃, and the crystallization time is 5~15 days; the drying temperature is 40 ℃, and the drying time is 1h-2h.

[0015] The application of the aforementioned nonlinear optical crystal, sodium lead aminosulfonate, in the fabrication of nonlinear optical devices.

[0016] An optical device comprising the aforementioned nonlinear optical crystal sodium lead aminosulfonate; the optical device includes a frequency multiplier, an optical parametric oscillator, and a frequency converter.

[0017] Beneficial effects: The nonlinear optical crystal sodium lead sulfamate prepared by this invention has a narrow ultraviolet cutoff edge, good environmental stability, mild preparation method, and low toxicity. This material system not only maintains the environmentally friendly characteristics of being Be-free, but also exhibits excellent environmental stability. The synthesis process is simple, reducing raw material costs and energy consumption, and it has good application prospects. Attached Figure Description

[0018] Figure 1 The single-crystal PXRD pattern of Na2Pb(SO3NH2)4; Figure 2 The elemental analysis spectrum of Na2Pb(SO3NH2)4; Figure 3 Characterization spectrum of the thermal properties of Na2Pb(SO3NH2)4; Figure 4 The infrared absorption spectrum of Na2Pb(SO3NH2)4 is shown below. Figure 5 The spectrum of Na2Pb(SO3NH2)4 is shown. (a) UV-Vis-NIR diffuse reflectance spectrum; (b) optical bandgap diagram; Figure 6 The test spectra of the second-order nonlinear optical properties of Na2Pb(SO3NH2)4 are shown. (a) Powder frequency doubling effect test spectrum, (b) Oscilloscope signal spectrum; Figure 7 The theoretical birefringence spectrum of Na2Pb(SO3NH2)4; Figure 8 The theoretically calculated bandgap spectrum of Na2Pb(SO3NH2)4; Figure 9 The density of states spectrum of Na2Pb(SO3NH2)4; Figure 10 The following are structural diagrams of Na2Pb(SO3NH2)4: (a) Coordination environment of Na1 atoms in Na2Pb(SO3NH2)4, (b) Coordination environment of Pb atoms, (c) Coordination environment of Na2 atoms, (d) Diagram of the smallest asymmetric unit, (e) Diagram of one-dimensional connection mode, and (f) Unit cell structure diagram of Na2Pb(SO3NH2)4 crystal. Figure 11 The diagram shows the working principle of the nonlinear optical device fabricated for this invention. Detailed Implementation

[0019] The present invention will now be described in detail with reference to specific embodiments. These embodiments are based on the technical solution of the present invention and provide detailed implementation methods and specific operating procedures. However, the scope of protection of the present invention is not limited to the following embodiments. Unless otherwise specified, the equipment used in the following embodiments is conventional equipment in the art; unless otherwise specified, the reagents used are commercially available products or prepared using conventional methods in the art. Specific details not described in the following embodiments can be achieved using conventional experimental methods in the art.

[0020] Example 1

[0021] The preparation of the nonlinear optical crystal sodium lead aminosulfonate Na2Pb(SO3NH2)4 includes the following steps: Weigh out Na2CO3, PbCO3, and HSO3NH2 in a molar ratio of 3:4:14; Mixing: Place the above raw materials into a 100 mL beaker and add 40 mL of deionized water. Stir to mix evenly. The stirring speed is 1200 rpm and the stirring time is 1 h. Constant temperature: Transfer the clear solution to a constant temperature water bath, then seal the mouth of the beaker with sealing film, and then poke several small holes in the film. Place the solution in a clean, uncontaminated environment with no air convection. The temperature of the constant temperature water bath is 35 ℃.

[0022] Crystallization: The crystallization temperature is 35 ℃ and the crystallization time is 10 days.

[0023] Washing: After obtaining pure crystals, filter the solution containing crystals and wash with water and 25% ethanol alternately. Drying: The crystal was placed in a vacuum drying oven, heated to 40 °C, and held at that temperature for 12 h to obtain the final crystal sample, which is a transparent nonlinear optical crystal, sodium lead aminosulfonate. Single-crystal testing was performed using a single-crystal diffractometer, and the single-crystal structure was analyzed using APEX4, thus confirming the crystal's chemical formula as Na2Pb(SO3NH2)4_C2221.

[0024] The nonlinear optical crystal sodium lead sulfamate (Na₂Pb(SO₃NH₂)₄) belongs to the orthorhombic crystal system, space group C₂₂₁, has a molecular weight of 637.524, and unit cell parameters a = 9.8213(4) Å, b = 9.8315(4) Å, c = 14.5136(6) Å, α = 90°, β = 90°, γ = 90°, Z = 4, V = 1401.41(10) Å. 3 .

[0025] Example 2

[0026] The preparation of Na2Pb(SO3NH2)4 includes the following steps: Weigh out Na2CO3, PbCO3, and HSO3NH2 in a molar ratio of 3:4:14; Mixing: Place the above raw materials into a 250 mL beaker and add 100 mL of deionized water. Stir to mix evenly, and then continue to add deionized water to adjust the pH of the solution to 4.5. The stirring speed is 1200 rpm and the stirring time is 1 h. Constant temperature: Transfer the clear solution to a constant temperature water bath, then seal the mouth of the beaker with sealing film, and then poke several small holes in the film. Place the solution in a clean, uncontaminated environment with no air convection. The temperature of the constant temperature water bath is 30 ℃.

[0027] Crystallization: The crystallization temperature is 30℃ and the crystallization time is 10 days.

[0028] Washing: After obtaining pure crystals, filter the solution containing crystals and wash with water and 25% ethanol alternately. Drying: The crystals were placed in a vacuum drying oven, heated to 40 °C and kept at that temperature for 12 h to obtain the final crystal sample, which is a transparent crystal of the compound sodium lead aminosulfonate.

[0029] Example 3

[0030] The difference from Example 2 is that the raw materials were placed in a 500mL beaker, 200mL of deionized water was added, and the mixture was stirred until homogeneous. Deionized water was then added to adjust the pH of the solution to 5. The temperature of the constant temperature water bath was 35℃, and the crystallization temperature was 35℃. The remaining preparation steps were the same as those for the raw materials.

[0031] Example 4

[0032] The difference from Example 2 is that the raw materials were placed in a 500mL beaker, 200mL of deionized water was added, and the mixture was stirred until homogeneous. Deionized water was then added to adjust the pH of the solution to 5.5. The temperature of the constant temperature water bath was 40℃, and the crystallization temperature was 40℃. The remaining preparation steps were the same as those for the raw materials.

[0033] Example 5

[0034] The difference from Example 2 is that the raw materials were placed in a 500mL beaker, 200mL of deionized water was added, and the mixture was stirred until homogeneous. Deionized water was then added to adjust the pH of the solution to 6. The temperature of the constant temperature water bath was 40℃, and the crystallization temperature was 40℃. The remaining preparation steps were the same as those for the raw materials.

[0035] Comparative Example 1 The steps include: Weigh out Na2CO3, PbCO3, and HSO3NH2 in a molar ratio of 1:4:10; Mixing: Place the above raw materials into a 100 mL beaker and add 40 mL of deionized water. Stir to mix evenly. The stirring speed is 1200 rpm and the stirring time is 1 h. Constant temperature: Transfer the clear solution to a constant temperature water bath, then seal the mouth of the beaker with sealing film, and then poke several small holes in the film. Place the solution in a clean, uncontaminated environment with no air convection. The temperature of the constant temperature water bath is 35 ℃.

[0036] Crystallization: The crystallization temperature is 35 ℃ and the crystallization time is 10 days.

[0037] Washing: After obtaining pure crystals, filter the solution containing crystals and wash with water and 25% ethanol alternately. Drying: The crystals were placed in a vacuum drying oven and heated to 40 °C and kept at that temperature for 12 h to obtain the final crystal sample. The single crystal of the product was measured to be a=7.08 Å, b=7.17 Å, c=15.29 Å, α=90°, β=102°, γ=90°. After comparison, it was found to be a known substance: Pb(NH2SO3)2·H2O.

[0038] Comparative Example 2 The difference from Example 1 is that when Na2CO3, PbCO3 and HSO3NH2 are weighed in a molar ratio of 2:4:12, 4:4:16 or 1:4:10, the other steps are the same as in Example 1, and the final crystal samples obtained do not have a frequency doubling effect.

[0039] The nonlinear optical crystal sodium lead aminosulfonate obtained in Examples 1-5 was used to measure its linear (ultraviolet-infrared spectroscopy) and nonlinear (frequency doubling effect, etc.) optical properties to characterize its thermal stability.

[0040] Figure 1 The XRD pattern of the nonlinear crystal Na2Pb(SO3NH2)4 is shown. It is observed that the experimental PXRD pattern matches the simulated theoretical pattern obtained from the single crystal structure analysis very well, indicating that the prepared experimental material is a pure phase.

[0041] Figure 2 The elemental analysis spectrum of sodium lead sulfamate, a nonlinear optical crystal, was obtained. The elemental composition and relative content of Na2Pb(SO3NH2)4 were determined by elemental analysis. The results were completely consistent with the single crystal structure analysis. All target elements were successfully detected, further confirming that the crystal obtained in the experiment is the target compound.

[0042] Figure 3 The thermal properties characterization spectrum of the nonlinear optical crystal sodium lead sulfamate (Na2Pb(SO3NH2)4) shows that the Na2Pb(SO3NH2)4 crystal exhibits good thermal stability at around 210 °C. Above this temperature, it begins to decompose. The experimental results show that the final remaining mass is 69% of the original sample, which is close to the calculated value of 69.85% of the theoretical remaining products Na2SO4 and PbSO4. The test and analysis results indicate that the Na2Pb(SO3NH2)4 crystal has good thermal stability. Thermogravimetric analysis (TGA) showed that the Sr(NO3)(NH2SO3)·H2O nonlinear optical crystal in the prior art ZL202310358393.2 (Xuefei Wang, Yang Li, Zilong Chen, Jihyun Lee, Fangfang Zhang, Kenneth R. Poeppelmeier*, Shilie Pan*, Kang Min Ok*, Sr(NO3)(NH2SO3)·H2O: First Nitrate Sulfamate Revealing Remarkable Second-Harmonic Generation and Optimized Birefringence, Small Struct., 2023, 4, 2300274.) exhibited thermal stability below 130 °C. The sample heated at 150 °C for 12 h directly decomposed into Sr(NO3)2 and Sr(NH2SO3)2, while the sample heated at 250 °C for 12 h showed the presence of Sr(NO3)2 and SrSO4.

[0043] Figure 4The infrared absorption spectrum of sodium lead aminosulfonate, a nonlinear optical crystal, is shown in the range of 1550-1650 cm⁻¹. -1 2200-2350 cm -1 and 3200-3500 cm -1 The region corresponds to the bending, rocking, and stretching vibrations of the [NH2] group; at 790-800 cm⁻¹ -1 880-950 cm -1 1050-1060 cm -1 and 1190-1250 cm -1 The region corresponds to antisymmetric and symmetric stretching of [SO3]. The assignment peaks of Na2Pb(SO3NH2)4 crystals are consistent with previously reported experimental and theoretical IR data for aminosulfonates.

[0044] Figure 5 The UV-Vis-NIR diffuse reflectance spectrum of sodium lead aminosulfonate, a nonlinear optical crystal; its UV-Vis-NIR diffuse reflectance spectrum is as follows. Figure 5 As shown in (a), the ultraviolet cutoff edge (λ) of Na₂Pb(SO₃NH₂)₄ crystal. cut-off The optical band gap is 258 nm, and the optical band gap diagram is as follows: Figure 5 As shown in (b) above, its optical bandgap was calculated to be 4.55 eV using the Kubelka-munk function, indicating that the crystal has a wide ultraviolet transmission window and a short ultraviolet cutoff edge. Meanwhile, the ultraviolet cutoff edge of Sr(NO3)(NH2SO3)·H2O is (λ...). cut-off The wavelength is 290 nm, and the optical band gap is 4.10 eV. Na2Pb(SO3NH2)4 is more suitable for working in the shorter wavelength ultraviolet region than Sr(NO3)(NH2SO3)·H2O.

[0045] Figure 6 The spectrum shows the second-order nonlinear optical properties of sodium lead aminosulfonate, a nonlinear optical crystal. Its powder frequency doubling effect is as follows: Figure 6 As shown in (a) of the diagram, the intensity of the second-order nonlinear optical effect of the compound increases with increasing particle size; the larger the particle size, the more significant the frequency doubling effect. The oscilloscope signal graph is shown below. Figure 6 As shown in (b) above. Samples with particle sizes between 180 and 280 μm were selected for the experiment, and the results showed that the overtone intensity was approximately 0.3 times that of KDP.

[0046] Figure 7 The theoretical birefringence spectrum of sodium lead sulfamate, a nonlinear optical crystal, shows that the refractive indices of its three principal axes satisfy the order ny > nx > nz. The calculated birefringence value at the characteristic wavelength of 546.1 nm is 0.0239.

[0047] Figure 8 The theoretical band gap spectrum of sodium lead sulfamate, a nonlinear optical crystal, was calculated. First-principles calculations based on density functional theory (DFT) were performed on the two compounds using the CASTEP software package. The indirect band gap of Na2Pb(SO3NH2)4 was calculated to be 4.5977 eV, which is in good agreement with the experimental value.

[0048] Figure 9 This is the density of states (DOS) spectrum of the nonlinear optical crystal sodium lead sulfamate. The top of the valence band is mainly occupied by N-2p and O-2p orbitals, while the bottom of the conduction band is mainly occupied by Pb-6p orbitals. Based on the above DOS analysis results, it can be concluded that (NH2SO3) - The n and o atomic orbitals in the functional group, together with the Pb atomic orbitals in the PbO4N4 polyhedron, participate in the electronic transition processes of the compound. Their synergistic effect determines the optical properties of the two Na2Pb(SO3NH2)4 compounds mentioned above.

[0049] The compounds obtained in Examples 1-5 were processed according to... Figure 11 As shown, placed in the corresponding position, at room temperature, an infrared beam with a wavelength of 1064 nm emitted by a Q-switched Nd:YAG laser is incident on a nonlinear optical crystal, sodium lead sulfamate, through a focusing lens, producing green frequency-doubled light with a wavelength of 532 nm. The outgoing beam contains infrared light with a wavelength of 1064 nm and green light with a wavelength of 532 nm. After being filtered out by a filter, the frequency-doubled light with a wavelength of 532 nm is obtained. A clear output of 532 nm frequency-doubled green light is observed, and the output intensity is about 0.3 times that of KDP under the same conditions.

[0050] It should be understood that the above description of the preferred embodiments is quite detailed, but it should not be considered as a limitation on the scope of protection of this invention. Those skilled in the art, under the guidance of this invention, can make substitutions or modifications without departing from the scope of protection of the claims of this invention, and all such substitutions or modifications fall within the scope of protection of this invention. The scope of protection of this invention should be determined by the appended claims.

Claims

1. A nonlinear optical crystal, sodium lead aminosulfonate, characterized in that, The chemical formula is Na2Pb(SO3NH2)4, which belongs to the orthorhombic crystal system, space group C2221, molecular weight is 637.524, and unit cell parameters are a=9.8213(4) Å, b=9.8315(4) Å, c=14.5136(6) Å, α=90°, β=90°, γ=90°.

2. The nonlinear optical crystal sodium lead aminosulfonate according to claim 1, characterized in that, The powder frequency doubling efficiency of the crystal is 0.3 times that of KH2PO4, and the crystal is a transparent crystal with an ultraviolet cutoff edge of 258 nm.

3. A method for preparing the nonlinear optical crystal sodium lead aminosulfonate as described in claim 1 or 2, characterized in that, include: S1. Add sodium source, lead source and aminosulfonic acid to a beaker, then add deionized water and stir to react; S2. Continue to add deionized water to the solution after the reaction to adjust the pH of the solution, and obtain a mixed solution; S3. The mixed solution of S2 is reacted and crystallized in a constant temperature water bath using an aqueous solution method. After filtration, washing, and drying, a transparent crystal of the compound is obtained, which is the nonlinear optical crystal sodium lead aminosulfonate.

4. The method for preparing the nonlinear optical crystal sodium lead aminosulfonate according to claim 3, characterized in that, The molar ratio of the sodium source, lead source, and aminosulfonic acid is 3:4:

14.

5. The method for preparing the nonlinear optical crystal sodium lead aminosulfonate according to claim 3, characterized in that, The sodium source is sodium carbonate or sodium hydroxide.

6. The method for preparing the nonlinear optical crystal sodium lead aminosulfonate according to claim 3, characterized in that, The lead source is lead carbonate or lead acetate.

7. The method for preparing the nonlinear optical crystal sodium lead aminosulfonate according to claim 3, characterized in that, The steps of the aqueous solution method include: transferring the clear mixed solution into a constant temperature water bath, sealing the mouth of the beaker with a sealing film, punching several small holes in the film, and placing the solution in a clean, uncontaminated environment with no air convection.

8. The method for preparing the nonlinear optical crystal sodium lead aminosulfonate according to claim 3, characterized in that, In step S3, the temperature of the constant temperature water bath is 30 ℃-40 ℃, the crystallization temperature is 30 ℃-40 ℃, and the crystallization time is 5~15 days; the drying temperature is 40 ℃, and the drying time is 1h-2h.

9. The use of sodium lead aminosulfonate, a nonlinear optical crystal as described in claim 1 or 2, in the fabrication of optical devices.

10. An optical device, characterized in that, It contains sodium lead aminosulfonate, a nonlinear optical crystal as described in claim 1 or 2; the optical device includes a frequency multiplier, an optical parametric oscillator, and a frequency converter.

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