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

Abstract

The application discloses a fluorine-containing zirconium phosphate compound, a nonlinear optical crystal thereof and a preparation method and application thereof, and belongs to the technical field of inorganic functional crystal materials. The chemical formula of the fluorine-containing zirconium phosphate compound is ZrPO4F. The nonlinear optical crystal is composed of a [PO4] tetrahedron and a fluorine-containing zirconium coordination polyhedron to form a three-dimensional skeleton structure, zirconium is six-coordinated and forms a zirconium oxygen coordination polyhedron containing F; the nonlinear optical crystal is a non-centrosymmetric crystal; the nonlinear optical crystal is of an orthorhombic system; the space group of the nonlinear optical crystal is Pna 21; the cell parameters of the nonlinear optical crystal are a = 11.6094 (5) Å, b = 6.9038 (3) Å, c = 5.4921 (2) Å, α = β = γ = 90°, Z = 4, and the unit cell volume is V = 440.19 (3) Å 3 . The nonlinear optical crystal has a nonlinear optical effect, a large band gap (deep ultraviolet transparency), a wide transmission range and easy preservation, and is a nonlinear optical crystal material with great potential application value.

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] 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] Second-order nonlinear optical (NLO) crystals can achieve frequency transformations such as frequency doubling, sum-frequency response, difference-frequency response, and optical parametric processes, making them crucial core materials in fields such as solid-state lasers, precision spectroscopy, photolithography, and information processing. For the deep ultraviolet band (especially around 200 nm and below), materials not only need a large band gap and good ultraviolet transmittance, but also require a non-centrosymmetric crystal structure with a certain degree of birefringence to achieve phase matching. Existing deep ultraviolet NLO crystal systems often face the challenge of simultaneously achieving deep ultraviolet transparency, frequency doubling response, and birefringence; furthermore, some materials suffer from limitations such as toxicity, difficulty in growth, or insufficient stability. 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 ZrPO4F. Its nonlinear optical crystal consists of a three-dimensional framework structure formed by connecting [PO4] tetrahedra with fluorinated zirconium coordination polyhedra; zirconium is hexagonally coordinated and forms F-containing zirconium-oxygen coordination polyhedra; the nonlinear optical crystal is a non-centrosymmetric crystal; the nonlinear optical crystal is orthorhombic; the space group of the nonlinear optical crystal is [missing information]. Pna 21; The unit cell parameters of a nonlinear optical crystal are a =11.6094(5)Å, b =6.9038(3)Å, c =5.4921(2)Å, α = β = γ =90°, Z=4, unit cell volume is V=440.19(3)Å 3 This nonlinear optical crystal exhibits nonlinear optical effects, has a large band gap (transparent in deep ultraviolet), a wide transmission range, and is easy to store, making it a nonlinear optical crystal material with great potential application value.

[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 ZrPO4F.

[0007] According to a second aspect of this application, a nonlinear optical crystal containing the fluorinated zirconium phosphate compound described above is provided.

[0008] A nonlinear optical crystal of the fluorinated zirconium phosphate compound described above, wherein the nonlinear optical crystal is composed of a three-dimensional framework structure formed by connecting [PO4] tetrahedra and fluorinated zirconium coordination polyhedra, wherein zirconium is hexacoordinated and forms F-containing zirconium-oxygen coordination polyhedra; The nonlinear optical crystal is a non-centrosymmetric crystal; The nonlinear optical crystal is an orthorhombic crystal system; The space group of the nonlinear optical crystal is Pna twenty one; The cell parameters of the nonlinear optical crystal are: a =11.6094(5)Å, b =6.9038(3)Å, c =5.4921(2)Å, α = β = γ =90°, Z=4, unit cell volume is V=440.19(3)Å 3 .

[0009] 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.

[0010] A method for preparing the above-described nonlinear optical crystal containing fluorinated zirconium phosphate compound, the method comprising the following steps: S1. Mix the zirconium source and phosphorus 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.

[0011] Optionally, in S1, the zirconium source is ZrF4.

[0012] Optionally, in S1, the phosphorus source is NH4H2PO4.

[0013] Optionally, in S1, the molar ratio of the zirconium source to the phosphorus source is (0.5-2.0):(0.5-2.0).

[0014] Optionally, in step S1, water is also added to the reactor.

[0015] Optionally, the reactor is a polytetrafluoroethylene-lined stainless steel hydrothermal reactor; The volume of the reaction vessel is 10-50 mL.

[0016] Optionally, in S2, the rate of temperature increase is 15~35℃ / h; The target temperature is 200~250℃, and the constant temperature time is 5000~10000 min; The cooling rate of the program is 2~6.8℃ / h.

[0017] Optionally, in step S2, the nonlinear optical crystal containing fluorinated zirconium phosphate compound is sequentially subjected to separation, washing, and drying.

[0018] 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 a nonlinear optical frequency conversion device, the nonlinear optical frequency conversion device comprising a nonlinear crystal element in a frequency multiplier, a sum / difference frequency converter, or an optical parametric oscillator / amplifier.

[0019] According to a fifth aspect of this application, a nonlinear optical device is provided, the nonlinear optical device comprising the nonlinear optical crystal of the fluorinated zirconium phosphate compound described above.

[0020] The beneficial effects that this application can produce include: (1) The nonlinear optical crystal in this application has a polar non-centrosymmetric structure. Pna 21), which is a structural prerequisite for satisfying second-order nonlinear optical effects.

[0021] (2) The nonlinear optical crystal still maintains a high reflectance of more than 90% at 200nm (corresponding to the deep ultraviolet transparent feature), indicating that it can be used for deep ultraviolet related optical windows.

[0022] (3) At a fundamental frequency of 1064 nm, the overtone response of the nonlinear optical crystal is about 1.6 times that of the potassium dihydrogen phosphate crystal, and it exhibits phase-matching characteristics (with increasing particle size and tending to plateau).

[0023] (4) The birefringence measured at 550 nm is approximately 0.026, which can provide the necessary anisotropic basis for phase matching.

[0024] (5) Nonlinear optical crystals are colorless and transparent, and thermal analysis shows that they have good thermal stability at temperatures ≤475K. Attached Figure Description

[0025] Figure 1This is a schematic diagram of the structure of the nonlinear optical crystal prepared in Example 1 of this application.

[0026] 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.

[0027] 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.

[0028] 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.

[0029] Figure 5 This is a schematic diagram of the birefringence test results of the nonlinear optical crystal prepared in Example 1 of this application.

[0030] 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

[0031] The present application is described in detail below with reference to the embodiments, but the present application is not limited to these embodiments.

[0032] Unless otherwise specified, all raw materials used in the embodiments of this application were purchased through commercial channels.

[0033] The nonlinear optical crystal in this embodiment is prepared by a hydrothermal reaction method, and the reaction equation is ZrF4 + NH4H2PO4 = ZrPO4F + 3HF↑ + NH3↑.

[0034] Unless otherwise specified, all test methods are standard and all instrument settings are those recommended by the manufacturer.

[0035] Example 1 Weigh 1 mmol of NH4H2PO4 and 1 mmol of ZrF4, place them in an agate mortar and grind them thoroughly for at least 5 minutes to ensure they are mixed evenly. Transfer the mixed powder to a 25 mL polytetrafluoroethylene-lined reactor and add 0.5 mL of deionized water as a mineralizing agent.

[0036] After sealing the reaction vessel, it was placed in an oven and heated from room temperature to 503 K (approximately 230 °C) within 500 min, and held at this temperature for 8000 min. Then, it was slowly cooled to 303 K (approximately 30 °C) within 3000 min using a programmed cooling method. The reaction product was removed, filtered, washed with ethanol, and dried to obtain colorless and transparent ZrPO4F single crystals.

[0037] Example 2 Weigh 5 mmol of NH4H2PO4 and 5 mmol of ZrF4, place them in an agate mortar and grind them thoroughly for at least 5 minutes to ensure they are mixed evenly. Transfer the mixed powder to a 25 mL polytetrafluoroethylene-lined reactor and add 1 mL of deionized water as a mineralizing agent.

[0038] After sealing the reaction vessel, it was placed in an oven and heated to 230°C at a rate of 25°C / h, held at that temperature for 5.5 days, and then slowly cooled to room temperature at a rate of 3°C / h. The reaction product was then removed, filtered, washed with ethanol, and dried to obtain colorless and transparent ZrPO4F single crystals.

[0039] Example 3 Weigh 1 mmol of NH4H2PO4 and 1 mmol of ZrF4, place them in an agate mortar and grind them thoroughly for at least 5 minutes to ensure they are mixed evenly. Transfer the mixed powder to a 25 mL polytetrafluoroethylene-lined reactor (without adding additional water).

[0040] After sealing the reaction vessel, it was placed in an oven and heated to 230°C at a rate of 30°C / h and kept at that temperature for 5.5 days. Then, it was slowly cooled to room temperature over a 3000-minute time. The reaction product was then removed, filtered, washed with ethanol, and dried to obtain colorless and transparent ZrPO4F single crystals.

[0041] Example 4 Weigh 5 mmol of NH4H2PO4 and 6 mmol of ZrF4, place them in an agate mortar and grind them thoroughly for at least 5 minutes to ensure they are mixed evenly. Transfer the mixed powder to a 25 mL polytetrafluoroethylene-lined reactor and add 1 mL of deionized water as a mineralizing agent.

[0042] After sealing the reaction vessel, it was placed in an oven and heated to 225°C at 25°C / h and kept at that temperature for 5 days. Then, it was slowly cooled to room temperature at 3°C / h. The reaction product was removed, filtered, washed with ethanol, and dried to obtain colorless and transparent ZrPO4F single crystals.

[0043] Example 5 Weigh 45 mmol of NH4H2PO4 and 45 mmol of ZrF, place them in an agate mortar and grind them thoroughly for at least 5 minutes to ensure they are evenly mixed. Transfer the mixed powder to a 25 mL polytetrafluoroethylene-lined reactor, add 0.5 mL of deionized water and 10 μL of 40% HF solution as mineralizing agents.

[0044] After sealing the reaction vessel, it was placed in an oven and heated to 220°C at a rate of 20°C / h and kept at that temperature for 6.5 days. Then, it was slowly cooled to room temperature at a rate of 3°C / h. The reaction product was then removed, filtered, washed with ethanol, and dried to obtain colorless and transparent ZrPO4F single crystals.

[0045] Example 6 Weigh 5 mmol of NH4H2PO4 and 45 mmol of ZrF, place them in an agate mortar and grind them thoroughly for at least 5 minutes to ensure they are evenly mixed. Transfer the mixed powder to a 25 mL polytetrafluoroethylene-lined reactor, add 12.5 mg of ZrPO4F seed crystals, and then add 1 mL of deionized water as a mineralizing agent.

[0046] After sealing the reaction vessel, it was placed in an oven and heated to 230°C at 25°C / h. The temperature was maintained for 3 days to allow it to fully dissolve and recrystallize. Then, the temperature was slowly lowered to room temperature at 1.5°C / h. The reaction product was removed, filtered, washed with ethanol, and dried to obtain ZrPO4F single crystals with larger size and higher transparency.

[0047] 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 composed of a three-dimensional framework structure formed by connecting [PO4] tetrahedra and fluorine-containing zirconium coordination polyhedra, with zirconium being six-coordinated and forming F-containing zirconium-oxygen coordination polyhedra.

[0048] 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.

[0049] 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.

[0050] The ultraviolet-visible diffuse reflectance / transmittance properties of nonlinear optical crystals are tested, such as... Figure 4As 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.

[0051] 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 =0.026@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.

[0052] 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 multiplier, a frequency converter, or an optical parametric oscillator, etc.

[0053] 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 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 ZrPO4F.

2. A nonlinear optical crystal containing a fluorinated zirconium phosphate compound as described in claim 1, characterized in that, The nonlinear optical crystal is composed of a three-dimensional framework structure formed by connecting [PO4] tetrahedra and fluorine-containing zirconium coordination polyhedra, with zirconium being six-coordinated and forming F-containing zirconium-oxygen coordination polyhedra. The nonlinear optical crystal is a non-centrosymmetric crystal; The nonlinear optical crystal is an orthorhombic crystal system; The space group of the nonlinear optical crystal is: Pna twenty one; The cell parameters of the nonlinear optical crystal are: a =11.6094(5)Å, b =6.9038(3)Å, c =5.4921(2)Å, α = β = γ =90°, Z=4, unit cell volume is V=440.19(3)Å 3 .

3. A method for preparing a nonlinear optical crystal containing a fluorinated zirconium phosphate compound as described in claim 2, characterized in that, The preparation method includes the following steps: S1. Mix the zirconium source and phosphorus 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.

4. The preparation method according to claim 3, characterized in that, In S1, the zirconium source is ZrF4; Preferably, in S1, the phosphorus source is NH4H2PO4.

5. The preparation method according to claim 3, characterized in that, In S1, the molar ratio of the zirconium source to the phosphorus source is (0.5-2.0):(0.5-2.0).

6. The preparation method according to claim 3, characterized in that, S1 also includes adding water to the reaction vessel; Preferably, the reactor is a polytetrafluoroethylene-lined stainless steel hydrothermal reactor; The volume of the reaction vessel is 10-50 mL.

7. The preparation method according to claim 3, characterized in that, In S2, the rate of temperature increase is 30~50℃ / h; The target temperature is 200~250℃, and the constant temperature time is 5000~10000 min; The cooling rate of the program is 2~6.8℃ / h.

8. The preparation method according to claim 3, characterized in that, 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 2 in the fabrication of a nonlinear optical frequency conversion device, characterized in that, The nonlinear optical frequency conversion device includes a frequency multiplier, a sum / difference frequency converter, or a nonlinear crystal element in an optical parametric oscillator / amplifier.

10. A nonlinear optical device, characterized in that, The nonlinear optical device includes the nonlinear optical crystal of the fluorinated zirconium phosphate compound as described in claim 2.

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