A fluorine-containing zirconium phosphate compound, a nonlinear optical crystal thereof, and a preparation method and application thereof

Abstract

This application discloses a fluorinated zirconium phosphate compound, its nonlinear optical crystal, its preparation method, and its applications. The chemical formula of the fluorinated zirconium phosphate compound is Zr(H2PO4)(HPO4)F·nH2O, where 0≤n≤3, and n is an integer. Its nonlinear optical crystal consists of a two-dimensional infinite layered structure formed by [ZrO5F] coordination polyhedra and [HPO4] and [H2PO4] tetrahedra connected by shared oxygen atoms, with interlayer crystal water molecules forming a hydrogen bond network. The nonlinear optical crystal is a non-centrosymmetric crystal; it belongs to the monoclinic crystal system; and its space group is [missing information - likely a specific space group or group]. I 2; The unit cell parameters of a nonlinear optical crystal are a =10.1200(5)Å, b =6.5653(3)Å, c =15.6899(8), β =92.340(5), unit cell volume V =1041.58(9)Å 3 This nonlinear optical crystal possesses deep ultraviolet transparency, a considerable frequency doubling response, and high birefringence, thus meeting the application requirements of nonlinear optical devices. Furthermore, the preparation method has the advantages of simple operation, low cost, low pollution, and low toxicity of the raw materials used.

Description

Technical Field

[0001] This application relates to a fluorinated zirconium phosphate compound, its nonlinear optical crystal, its preparation method and application, belonging to the field of inorganic functional crystal materials technology. Background Technology

[0002] Since Franken first discovered the nonlinear optical effects of crystals in 1962, research on nonlinear optical crystal materials has gradually emerged. With the further development and widespread application of laser technology, nonlinear optical crystals currently have extremely broad application prospects in spectrometers, microelectronics, and information communication. Different application fields require different laser frequencies, and shorter wavelength ultraviolet and even deep ultraviolet lasers play a significant role in modern instruments such as medical devices, communications, photolithography, and ultra-high energy resolution photoelectron spectrometers. Currently, the development of all-solid-state deep ultraviolet laser sources has become a recent research hotspot in the international laser science community.

[0003] Deep ultraviolet (DUV) / UV nonlinear optical crystals can achieve laser frequency doubling and frequency conversion through second-order nonlinear processes, and are widely used in precision lithography, spectroscopy, information optics and other fields. Existing DUV crystal systems often face the following challenges: (1) it is difficult to balance deep UV transmittance with nonlinear effects; (2) crystal growthability, environmental stability and overall optical performance still need to be improved; (3) many systems introduce structural units that easily lead to redshift of the absorption edge when improving frequency doubling or birefringence. Therefore, it is urgent to develop a new material system that combines deep UV transparency, considerable frequency doubling and large birefringence, and can be controllably prepared and obtained as a single crystal. Summary of the Invention

[0004] To address the aforementioned technical problems, this application provides a fluorinated zirconium phosphate compound, its nonlinear optical crystal, its preparation method, and its applications. The chemical formula of the fluorinated zirconium phosphate compound is Zr(H₂PO₄)(HPO₄)F·nH₂O, where 0 ≤ n ≤ 3, and n is an integer. Its nonlinear optical crystal consists of a two-dimensional infinite layered structure formed by [ZrO₅F] coordination polyhedra and [HPO₄] and [H₂PO₄] tetrahedra connected by shared oxygen atoms, with interlayer crystal water molecules forming a hydrogen bond network. The nonlinear optical crystal is a non-centrosymmetric crystal; it belongs to the monoclinic crystal system; and its space group is [space group missing]. I 2; The unit cell parameters of a nonlinear optical crystal are a =10.1200(5)Å, b =6.5653(3)Å, c =15.6899(8), β =92.340(5), unit cell volume V =1041.58(9)Å 3This nonlinear optical crystal possesses deep ultraviolet transparency, a considerable frequency doubling response, and significant birefringence, thus meeting the application requirements of nonlinear optical devices.

[0005] According to a first aspect of this application, a fluorinated zirconium phosphate compound is provided.

[0006] A fluorinated zirconium phosphate compound, wherein the chemical formula of the fluorinated zirconium phosphate compound is Zr(H2PO4)(HPO4)F·nH2O, wherein 0≤n≤3, and n is an integer.

[0007] Optionally, n=3, and the chemical formula of the fluorinated zirconium phosphate compound is Zr(H2PO4)(HPO4)F·3H2O.

[0008] According to a second aspect of this application, a nonlinear optical crystal containing the fluorinated zirconium phosphate compound described above is provided.

[0009] A nonlinear optical crystal containing the aforementioned fluorinated zirconium phosphate compound, wherein the nonlinear optical crystal is a two-dimensional infinite layered structure formed by [ZrO5F] coordination polyhedra and [HPO4] and [H2PO4] tetrahedra connected by shared oxygen atoms, and contains water molecules of crystallization between the layers to form a hydrogen bond network; The nonlinear optical crystal is a non-centrosymmetric crystal; The nonlinear optical crystal is a monoclinic crystal system; The space group of the nonlinear optical crystal is: I 2; The cell parameters of the nonlinear optical crystal are: a =10.1200(5)Å, b =6.5653(3)Å, c =15.6899(8), β =92.340(5), unit cell volume V =1041.58(9)Å 3 .

[0010] According to a third aspect of this application, a method for preparing a nonlinear optical crystal containing a fluorinated zirconium phosphate compound as described above is provided.

[0011] A method for preparing the above-described nonlinear optical crystal containing fluorinated zirconium phosphate compound, the method comprising the following steps: S1. Mix the hydrogen bond donor, hydrogen bond acceptor, zirconium source, phosphorus source, and fluorine source, and place the mixture in a reaction vessel and seal it. S2. The sealed mixture is first heated to the target temperature, kept at a constant temperature, and then cooled down to obtain the nonlinear optical crystal containing the fluorinated zirconium phosphate compound.

[0012] Optionally, in S1, the hydrogen bond donor is urea.

[0013] Optionally, in S1, the hydrogen bond acceptor is tetramethylammonium chloride.

[0014] Optionally, in S1, the zirconium source is ZrOCl2.

[0015] Optionally, in S1, the phosphorus source is H3PO4.

[0016] Optionally, in S1, the fluorine source is HF.

[0017] Optionally, in S1, the molar ratio of the hydrogen bond donor, hydrogen bond acceptor, zirconium source, phosphorus source and fluorine source is (1-5):(1-3):1:(1-4):(0.1-2).

[0018] Optionally, in S1, mixing the hydrogen bond donor, hydrogen bond acceptor, zirconium source, phosphorus source, and fluorine source includes: first mixing the hydrogen bond donor and the hydrogen bond acceptor to obtain a deep eutectic solvent, and then adding the zirconium source, the phosphorus source, and the fluorine source for mixing.

[0019] Optionally, in S2, the rate of temperature increase is 20~30℃ / h; The target temperature is 200~250℃, and the constant temperature period is 1~5 days; The cooling rate of the program is 5~8℃ / h.

[0020] Optionally, in step S2, the nonlinear optical crystal containing fluorinated zirconium phosphate compound is sequentially subjected to separation, washing, and drying.

[0021] According to a fourth aspect of this application, an application is provided of the nonlinear optical crystal containing the fluorinated zirconium phosphate compound described above in the fabrication of nonlinear optical devices.

[0022] Optionally, the nonlinear optical device is at least one of a frequency multiplier generator, an optical parametric oscillator, and an up / down converter.

[0023] The beneficial effects that this application can produce include: (1) Nonlinear optical crystals are non-centrosymmetric crystals that satisfy the structural conditions of second-order nonlinear effects.

[0024] (2) The nonlinear optical crystal has outstanding deep ultraviolet transparency: the powder UV-Vis-NIR diffuse reflection shows that the reflectivity is >90% at 200nm.

[0025] (3) The nonlinear optical crystal has a strong frequency doubling response: the Kurtz-Perry powder method, at a fundamental frequency of 1064nm, the frequency doubling intensity of the powder is about 2.0 times that of potassium dihydrogen phosphate (particle size 75-120μm).

[0026] (4) The nonlinear optical crystal has a large birefringence: The 2D compound exhibits a birefringence level of 0.041@550nm, which is beneficial for phase matching.

[0027] (5) The nonlinear optical crystal has good thermal stability: the TG / DTA display system remains stable up to about 475K. Attached Figure Description

[0028] Figure 1 This is a schematic diagram of the structure of the nonlinear optical crystal prepared in Example 1 of this application.

[0029] Figure 2 The X-ray diffraction pattern is obtained by fitting the nonlinear optical crystal prepared in Example 1 of this application with its single crystal structure.

[0030] Figure 3 This is a schematic diagram of the frequency doubling test results of the nonlinear optical crystal prepared in Example 1 of this application.

[0031] Figure 4 This is a schematic diagram of the ultraviolet diffuse reflection / transmission characteristics of the nonlinear optical crystal prepared in Example 1 of this application at around 200 nm.

[0032] Figure 5 This is a schematic diagram of the birefringence test results of the nonlinear optical crystal prepared in Example 1 of this application.

[0033] Figure 6 This is a schematic diagram of the working principle of a nonlinear optical device made using the nonlinear optical crystal in Embodiment 1 of this application, wherein 1-laser, 2-incident laser beam, 3-nonlinear optical crystal, 4-outgoing laser beam, and 5-filter. Detailed Implementation

[0034] The present application is described in detail below with reference to the embodiments, but the present application is not limited to these embodiments.

[0035] Unless otherwise specified, all raw materials used in the embodiments of this application were purchased through commercial channels.

[0036] The nonlinear optical crystal in this embodiment is prepared by a hydrothermal reaction method, and the reaction equation is ZrOCl2·8H2O+2H3PO4+HF=Zr(H2PO4)(HPO4)F·3H2O+2HCl↑+5H2O.

[0037] Unless otherwise specified, all test methods are standard and all instrument settings are those recommended by the manufacturer.

[0038] Example 1 Weigh 2.8 g (46.6 mmol) of urea and 2.4 g (21.9 mmol) of tetramethylammonium chloride, place them in a beaker, preheat at 353 K and keep at that temperature for about 1500 min to form a clear and homogeneous deep eutectic solvent; then add 0.25 g (0.76 mmol) of ZrOCl2·8H2O, 20 μL (about 0.46 mmol) of HF (40% aqueous solution) and 104 μL (about 1.54 mmol) of H3PO4 (85% aqueous solution) to the solvent, mix well and transfer to a 25 mL polytetrafluoroethylene-lined reactor and seal it; place the reactor in an oven, heat it to 463 K (about 190 °C) and keep it at that temperature for 3000 min (about 50 h), and then slowly cool it to room temperature over about 1500 min. After the reaction is complete, the product is removed, filtered, washed with ethanol, and dried naturally to obtain colorless and transparent blocky / plate-like single crystals, namely Zr(H2PO4)(HPO4)F·3H2O crystals.

[0039] Example 2 The rest of the operation is the same as in Example 1, except that the amount of HF (40% aqueous solution) is adjusted to 10 μL (about 0.23 mmol).

[0040] Example 3 The rest of the operation is the same as in Example 1, except that the amount of HF (40% aqueous solution) is adjusted to 30 μL (about 0.69 mmol).

[0041] Example 4 The rest of the operation is the same as in Example 1, except that the amount of H3PO4 (85%) is adjusted to 80 μL (about 1.18 mmol).

[0042] Example 5 The remaining procedures were the same as in Example 1, except that a deep eutectic solvent was first prepared, followed by the addition of 1 mL of deionized water, then ZrOCl2·8H2O, HF, and H3PO4. The mixture was then loaded into a reactor and heated to 185°C for 3 days, followed by cooling to room temperature at a rate of 2°C / h. After the reaction was complete, the product was removed, filtered, washed with ethanol, and dried to obtain larger crystals with higher transparency.

[0043] Example 6 The remaining procedures were the same as in Example 1, except that ZrOCl2·8H2O, HF, and H3PO4 were added to the eutectic solvent, followed by 10 mg of Zr(H2PO4)(HPO4)F·3H2O seed crystals, and then the mixture was sealed in a reactor. The temperature was raised to approximately 190°C and held at that temperature for 48 hours to allow for complete dissolution and recrystallization. Subsequently, the mixture was cooled to room temperature at a rate of 2°C / h. After the reaction was complete, the product was removed, filtered, washed with ethanol, and dried to obtain larger crystals with higher transparency.

[0044] Characterization and Testing The nonlinear optical crystal prepared in Example 1 is taken as a typical example: Figure 1 This indicates that the nonlinear optical crystal is a two-dimensional infinite layered structure formed by the connection of [ZrO5F] coordination polyhedra and [HPO4] and [H2PO4] tetrahedra through shared oxygen atoms.

[0045] Figure 2 This indicates that the prepared nonlinear optical crystal is consistent with the X-ray diffraction pattern obtained by fitting its single crystal structure.

[0046] At room temperature, using an Nd:YAG laser as the fundamental frequency source, near-infrared laser with an incident wavelength of 1064 nm was used to generate a second harmonic through a ZrPO4F crystal, resulting in a green laser with an output wavelength of 532 nm (e.g., ...). Figure 3 As shown in the figure, this result indicates that nonlinear optical crystals can be applied to nonlinear optical fields such as frequency doubling and frequency conversion.

[0047] The ultraviolet-visible diffuse reflectance / transmittance properties of nonlinear optical crystals are tested, such as... Figure 4 As shown, the results indicate that the ultraviolet absorption cutoff edge of the nonlinear optical crystal is below 200 nm, and it has good optical transmittance characteristics in the wavelength range of 200-800 nm. At the same time, the nonlinear optical crystal is not easily broken or moisture-absorbing under normal conditions, making it easy to store and use in device fabrication.

[0048] Birefringence tests were performed on the nonlinear optical crystal using a polarizing microscope combined with a Berek compensator: when linearly polarized light was incident on the biaxial crystal in a non-optical axis direction, it split into two beams, resulting in an optical path difference. R With sample thickness T and birefringence Δ n satisfy R= Δ n×T Therefore, the birefringence value can be calculated by measuring the optical path difference and thickness. For example... Figure 5 As shown, the experimental birefringence of the nonlinear optical crystal at a wavelength of 550 nm is Δ n=0.041@550nm, which is basically consistent with the theoretical calculation value, indicating that the nonlinear optical crystal has a certain optical anisotropy, which can provide the necessary conditions for phase-matched frequency conversion.

[0049] like Figure 6 As shown, a laser beam 2 emitted by laser 1 enters a nonlinear optical crystal 3, and the resulting outgoing laser beam 4 passes through a filter 5 to obtain the desired laser beam. This nonlinear optical laser can be a frequency doubler, a frequency converter, or an optical parametric oscillator, etc.

[0050] The above description is merely a few embodiments of this application and is not intended to limit this application in any way. Although this application discloses preferred embodiments as described above, it is not intended to limit this application. Any changes or modifications made by those skilled in the art without departing from the scope of the technical solution of this application using the disclosed technical content are equivalent to equivalent implementation cases and all fall within the scope of the technical solution.

Claims

1. A fluorinated zirconium phosphate compound, characterized in that, The chemical formula of the fluorinated zirconium phosphate compound is Zr(H2PO4)(HPO4)F·nH2O, where 0≤n≤3 and n is an integer.

2. The fluorinated zirconium phosphate compound according to claim 1, characterized in that, n=3, and the chemical formula of the fluorinated zirconium phosphate compound is Zr(H2PO4)(HPO4)F·3H2O.

3. A nonlinear optical crystal of a fluorinated zirconium phosphate compound as described in claim 1 or 2, characterized in that, The nonlinear optical crystal is a two-dimensional infinite layered structure formed by [ZrO5F] coordination polyhedra and [HPO4] and [H2PO4] tetrahedra connected by shared oxygen atoms, and contains water molecules of crystallization between the layers to form a hydrogen bond network; The nonlinear optical crystal is a non-centrosymmetric crystal; The nonlinear optical crystal is a monoclinic crystal system; The space group of the nonlinear optical crystal is: I 2; The cell parameters of the nonlinear optical crystal are: a =10.1200(5)Å, b =6.5653(3)Å, c =15.6899(8), β =92.340(5), unit cell volume V =1041.58(9)Å 3 .

4. A method for preparing a nonlinear optical crystal containing a fluorinated zirconium phosphate compound as described in claim 3, characterized in that, The preparation method includes the following steps: S1. Mix the hydrogen bond donor, hydrogen bond acceptor, zirconium source, phosphorus source, and fluorine source, and place the mixture in a reaction vessel and seal it. S2. The sealed mixture is first heated to the target temperature, kept at a constant temperature, and then cooled down to obtain the nonlinear optical crystal containing the fluorinated zirconium phosphate compound.

5. The preparation method according to claim 4, characterized in that, In S1, the hydrogen bond donor is urea; Preferably, in S1, the hydrogen bond acceptor is tetramethylammonium chloride; Preferably, in S1, the zirconium source is ZrOCl2; Preferably, in S1, the phosphorus source is H3PO4; Preferably, in S1, the fluorine source is HF.

6. The preparation method according to claim 4, characterized in that, In S1, the molar ratio of the hydrogen bond donor, hydrogen bond acceptor, zirconium source, phosphorus source and fluorine source is (1-5):(1-3):1:(1-4):(0.1-2).

7. The preparation method according to claim 4, characterized in that, In S1, the mixing of the hydrogen bond donor, hydrogen bond acceptor, zirconium source, phosphorus source, and fluorine source includes: first mixing the hydrogen bond donor and the hydrogen bond acceptor to obtain a deep eutectic solvent, and then adding the zirconium source, the phosphorus source, and the fluorine source and mixing them.

8. The preparation method according to claim 4, characterized in that, In S2, the rate of temperature increase is 30~50℃ / h; The target temperature is 200~250℃, and the constant temperature period is 1~5 days; The cooling rate of the program is 5~8℃ / h; Preferably, in step S2, the nonlinear optical crystal containing fluorinated zirconium phosphate compound is sequentially subjected to separation, washing, and drying.

9. The application of the nonlinear optical crystal containing a fluorinated zirconium phosphate compound as described in claim 3 in the fabrication of nonlinear optical devices.

10. The nonlinear optical device according to claim 9, characterized in that, The nonlinear optical device is at least one of a frequency multiplier generator, an optical parametric oscillator, and an up / down converter.

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