Solar-blind ultraviolet high-transmittance guanidine methylphosphonate nonlinear optical crystal as well as preparation method and application thereof

Abstract

The invention discloses a solar-blind ultraviolet region high-transmittance guanidine methylphosphonate nonlinear optical crystal and a preparation method and application thereof, the chemical formula of the crystal is [C (NH2) 3] 2 (CH3PO3), the crystal belongs to a monoclinic system, and the space group of the crystal is Cm (No.8). The guanidine methylphosphonate nonlinear optical material has excellent nonlinear optical performance, the powder frequency doubling intensity of the guanidine methylphosphonate nonlinear optical material is about 1.0 time of KDP, the light transmission range is wide, the ultraviolet cut-off edge is 207 nm, and frequency doubling laser output of an Nd: YAG (1064 nm) laser can be achieved. The growth method of the [C (NH2) 3] 2 (CH3PO3) crystal is simple, and the prepared crystal is high in quality, large in size and high in laser damage threshold (326.8 MW / cm < 2 >), is suitable for manufacturing a laser frequency conversion device, and can be applied to equipment such as an all-solid-state laser and an optical parametric oscillator.

Description

Technical Field

[0001] This invention belongs to the field of nonlinear optical crystal materials technology, and relates to a solar-blind guanidine methylphosphonate nonlinear optical crystal with high ultraviolet transmittance, its preparation method and application. Background Technology

[0002] Nonlinear optical crystals, as a core component of all-solid-state lasers, can generate new coherent beams through second harmonic generation, thus playing a crucial role in modern laser applications. In particular, nonlinear optical crystals capable of converting laser wavelengths to the ultraviolet region have gradually become a research hotspot due to their key roles in high-precision micromachining, ultra-high-resolution lithography, laser processing technology, biomedicine, and advanced scientific instruments. To date, ultraviolet nonlinear optical crystals such as β-BaB₂O₄ (BBO), LiB₃O₅ (LBO), KH₂PO₄ (KDP), and L-arginine phosphate monohydrate (LAP) have been developed and successfully commercialized. On the other hand, the solar-blind ultraviolet region (210-280 nm) demonstrates unique application value in fields such as communications, food sterilization, fire alarm systems, and unmanned aerial vehicles (UAVs). With the rapid development of laser science and technology, the exploration of high-performance novel ultraviolet nonlinear optical crystal materials has become particularly urgent. An ideal ultraviolet nonlinear optical crystal should possess excellent properties such as a wide transparency range that can cover the solar-blind ultraviolet region, second-order nonlinear optical effects comparable to KDP, and moderate birefringence to achieve phase matching. It should also have good physicochemical stability and crystal growth characteristics, as well as a high laser damage threshold. Summary of the Invention

[0003] To obtain an ideal ultraviolet nonlinear optical crystal, this invention provides a guanidine methylphosphonate compound. The nonlinear optical crystal based on this compound has excellent properties such as a wide transparency range that can cover the solar-blind ultraviolet region, a second-order nonlinear optical effect comparable to KDP, and a moderate birefringence to achieve phase matching. It also has good physicochemical stability and crystal growth characteristics, as well as a high laser damage threshold.

[0004] Specifically, the present invention provides a methylphosphonic acid guanidine compound with the chemical formula [C(NH2)3]2(CH3PO3).

[0005] The present invention also provides a method for preparing the methylphosphonic acid guanidine compound, which is also referred to as Method 1, and includes the following steps:

[0006] The methylphosphonic acid, guanidine carbonate, and methanol were mixed and subjected to a solvothermal reaction to obtain the guanidine methylphosphonate compound.

[0007] According to an embodiment of the present invention, the temperature of the solvothermal reaction is 100-150°C, exemplarily 120°C; the time of the solvothermal reaction is 1-60 hours, exemplarily 48 hours.

[0008] According to an exemplary embodiment of the present invention, the solvothermal reaction employs programmed temperature control: for example, the temperature is increased from room temperature (e.g., 30°C) to 120°C within 120 minutes at a heating rate of 45°C / hour, held at the temperature for 48 hours, and then cooled back to room temperature at a rate of 1.25°C / hour.

[0009] According to an embodiment of the present invention, the molar volume ratio of methylphosphonic acid, guanidine carbonate and methanol is (1-5) mmol:(1-5) mmol:(1-5) mL, for example 2 mmol:2 mmol:3 mL.

[0010] This invention also provides a method for preparing the guanidine methylphosphonate crystals, which is also referred to as Method Two, and includes the following steps:

[0011] Methylphosphonic acid, guanidine carbonate, lithium carbonate and water are mixed to obtain a reaction solution, which is then filtered and evaporated to obtain the guanidine methylphosphonic acid crystals.

[0012] According to an embodiment of the present invention, lithium carbonate plays a role in adjusting the pH.

[0013] According to an embodiment of the present invention, the evaporation temperature is room temperature to 50°C, for example, 40°C.

[0014] According to an embodiment of the present invention, the molar volume ratio of methylphosphonic acid, guanidine carbonate, lithium carbonate and water is (5-15) mmol:(5-15) mmol:(10-20) mmol:(10-30) mL, for example 10 mmol:10 mmol:18 mmol:20 mL.

[0015] According to an embodiment of the present invention, the pH value of the reaction solution is 8-9, exemplarily 8, 8.5, or 9. In this reaction system, the pH value of the reaction solution has a significant impact on the synthesis of the crystal. A certain amount of lithium carbonate can be added as an acid-base adjuster to ensure the final pH value of the reaction solution is between 8 and 9.

[0016] The present invention also provides a guanidine methylphosphonate crystal, the chemical formula of which is [C(NH2)3]2(CH3PO3), belonging to the monoclinic crystal system.

[0017] According to an embodiment of the present invention, the cell parameters of the guanidine methylphosphonate crystal are as follows: α=γ=90°, β=119.324°(5),

[0018] According to an embodiment of the present invention, the guanidine methylphosphonate crystal is a transparent crystal.

[0019] According to an embodiment of the present invention, the guanidine methylphosphonate crystal has a substantially as follows Figure 1 The crystal structure shown.

[0020] According to an embodiment of the present invention, the guanidine methylphosphonate crystal is a nonlinear optical crystal.

[0021] According to an embodiment of the present invention, the guanidine methylphosphonate crystal has a substantially as follows Figure 2 The topographic diagram shown.

[0022] According to an embodiment of the present invention, the size of the guanidine methylphosphonate crystal is greater than 5 mm, preferably greater than 6 mm, for example 6.1 mm.

[0023] According to an embodiment of the present invention, the guanidine methylphosphonate crystal has a substantially as follows Figure 3 The X-ray powder diffraction pattern shown.

[0024] According to an embodiment of the present invention, the guanidine methylphosphonate crystal has a substantially as follows Figure 4 The optical transmittance in the ultraviolet-visible region is shown, with an ultraviolet absorption cutoff edge of 207 nm.

[0025] According to an embodiment of the present invention, the guanidine methylphosphonate crystals with a particle size of 150-212 μm, under 1064 nm laser irradiation, exhibit essentially the following properties: Figure 5 The second harmonic signal is shown.

[0026] According to an embodiment of the present invention, the guanidine methylphosphonate crystal shown has an overtone intensity of 1.0 times that of KH2PO4 (KDP).

[0027] According to an embodiment of the present invention, the guanidine methylphosphonate crystal can achieve phase matching under 1064nm laser irradiation, and has essentially the same properties as... Figure 6 The frequency doubling effect-particle size diagram is shown.

[0028] According to an embodiment of the present invention, the guanidine methylphosphonate crystals only begin to decompose in a nitrogen atmosphere until the temperature reaches 262.8°C, and have essentially the following properties: Figure 7 The thermogravimetric curve is shown.

[0029] According to an embodiment of the present invention, the guanidine methylphosphonate crystal remains structurally stable at 180°C in air, and has essentially the same properties as described above. Figure 8 The X-ray diffraction pattern of the variable-temperature powder is shown.

[0030] The present invention also provides a method for preparing the above-mentioned methylphosphonic acid guanidine crystals, which includes a method for preparing the above-mentioned methylphosphonic acid guanidine compound.

[0031] The present invention also provides an application of the above-mentioned guanidine methylphosphonate crystal as a nonlinear optical crystal material. Preferably, it is used as a nonlinear optical crystal material for solar-blind ultraviolet transmission.

[0032] The present invention also provides a nonlinear optical crystal material, namely the guanidine methylphosphonate crystal.

[0033] The present invention also provides the application of the guanidine methylphosphonate compound and / or guanidine methylphosphonate crystal and / or nonlinear optical crystal material in visible light frequency doubling laser output.

[0034] The present invention also provides the application of the guanidine methylphosphonate compound and / or guanidine methylphosphonate crystal and / or nonlinear optical crystal material in all-solid-state lasers and optical parametric oscillators; for example, the all-solid-state laser is used in laser communication, laser processing, laser medicine or semiconductor processing.

[0035] The present invention also provides an optical device comprising the above-mentioned guanidine methylphosphonate compound and / or guanidine methylphosphonate crystal and / or nonlinear optical crystal material.

[0036] According to an embodiment of the present invention, the optical device is a nonlinear optical device, such as an all-solid-state laser or an optical parametric oscillator.

[0037] The beneficial effects of this invention are:

[0038] 1. This invention provides the first-ever acquisition of guanidine methylphosphonate [C(NH2)3]2(CH3PO3) crystal and its application as a nonlinear optical crystal. This crystal exhibits excellent nonlinear optical properties (its powder frequency doubling intensity is approximately 1.0 times that of KDP), a wide transmission range, and a short deep ultraviolet cutoff edge (207 nm), and is capable of achieving frequency-doubled laser output from Nd:YAG (1064 nm) lasers.

[0039] 2. The growth method of the methylphosphonate guanidine [C(NH2)3]2(CH3PO3) crystal of the present invention is simple, and the prepared crystal has high quality, large size, and a high laser damage threshold (326.8 MW / cm). 2 It is suitable for making laser frequency conversion devices and can be used in devices such as all-solid-state lasers and optical parametric oscillators. Attached Figure Description

[0040] Figure 1 This is a schematic diagram of the structure of guanidine methylphosphonate [C(NH2)3]2(CH3PO3) crystal prepared in Example 1 of the present invention;

[0041] Figure 2 (a) and (b) are photographs of the methylphosphonate guanidine [C(NH2)3]2(CH3PO3) crystals prepared in Examples 1 and 2 of this invention, respectively.

[0042] Figure 3 These are the experimental X-ray powder diffraction patterns and theoretically simulated X-ray powder diffraction patterns of the methylphosphonate guanidine [C(NH2)3]2(CH3PO3) crystal prepared in Example 1 of this invention.

[0043] Figure 4 This is a UV-Vis transmission image of the guanidine methylphosphonate [C(NH2)3]2(CH3PO3) crystal prepared in Example 1 of this invention;

[0044] Figure 5 This is a second harmonic signal diagram of guanidine methylphosphonate [C(NH2)3]2(CH3PO3) crystals with a particle size of 150-212 μm under 1064 nm laser irradiation.

[0045] Figure 6 This is a graph showing the relationship between the magnitude of the frequency doubling effect and the particle size of the methylphosphonate guanidine [C(NH2)3]2(CH3PO3) crystal prepared in Example 1 of this invention under 1064nm laser irradiation.

[0046] Figure 7 The thermogravimetric curve of guanidine methylphosphonate [C(NH2)3]2(CH3PO3) crystal prepared in Example 1 under nitrogen atmosphere.

[0047] Figure 8 These are variable-temperature powder X-ray diffraction and theoretically simulated X-ray powder diffraction patterns of the guanidine methylphosphonate [C(NH2)3]2(CH3PO3) crystal prepared in Example 1. Detailed Implementation

[0048] The crystal, its preparation method, and applications 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.

[0049] Unless otherwise stated, the raw materials and reagents used in the following examples are commercially available products or can be prepared by known methods.

[0050] Example 1

[0051] Methylphosphonic acid (2 mmol), guanidine carbonate (2 mmol), and 3 mL of methanol were added to a 25 mL stainless steel autoclave lined with polytetrafluoroethylene. The autoclave was heated from room temperature to 120 °C over 120 minutes and held at 120 °C for 2 days. Then, it was gradually cooled to room temperature at a rate of 1.25 °C / h. The mixture was filtered, and the solid product was washed with water to obtain a large amount of pure guanidine methylphosphonate [C(NH2)3]2(CH3PO3) crystals.

[0052] Example 2

[0053] Methylphosphonic acid (10 mmol), guanidine carbonate (10 mmol), and lithium carbonate (18 mmol) were dissolved in 20 mL of distilled water, filtered, and then evaporated at 40 °C for 3-10 days until the reaction solution crystallized, yielding colorless blocky [C(NH2)3]2(CH3PO3) crystals.

[0054] See Figure 1 The image shown is a crystal structure diagram of the methylphosphonate guanidine [C(NH2)3]2(CH3PO3) crystal prepared in Example 1.

[0055] Figure 2 In Figures (a) and (b), we can see the physical images of the methylphosphonic acid guanidine [C(NH2)3]2(CH3PO3) crystals prepared in Examples 1 and 2, respectively. As can be seen from the figures, the methylphosphonic acid guanidine [C(NH2)3]2(CH3PO3) crystals prepared in this invention have a large volume and a side length of up to 6.1 mm.

[0056] See Figure 3 The figure shows the X-ray powder diffraction pattern of the methylphosphonate guanidine [C(NH2)3]2(CH3PO3) crystal prepared in Example 1. As can be seen from the figure, the powder X-ray diffraction experimental pattern of the [C(NH2)3]2(CH3PO3) crystal at room temperature is consistent with the single crystal X-ray diffraction simulation pattern, which proves that the product is a pure phase.

[0057] See Figure 4 The figure shows the transmittance of the methylphosphonate guanidine [C(NH2)3]2(CH3PO3) crystal prepared in Example 1 in the ultraviolet-visible region. It can be seen from the figure that the ultraviolet cutoff edge of the methylphosphonate guanidine [C(NH2)3]2(CH3PO3) crystal prepared in this invention is 207 nm.

[0058] See Figure 5 As shown, the frequency doubling effect of the guanidine methylphosphonate [C(NH2)3]2(CH3PO3) crystal prepared in Example 1 is about 1.0 times that of commercial KDP (potassium dihydrogen phosphate) crystal.

[0059] See Figure 6As shown, the frequency doubling intensity of the guanidine methylphosphonate [C(NH2)3]2(CH3PO3) crystal prepared in Example 1 under 1064 nm laser irradiation continuously increases with the increase of particle size (the guanidine methylphosphonate [C(NH2)3]2(CH3PO3) crystal obtained in Example 1 was first ground into powder, and then sieved through stainless steel sieves of different apertures to obtain guanidine methylphosphonate [C(NH2)3]2(CH3PO3) crystals of different particle sizes). This indicates that it can achieve phase matching.

[0060] Laser damage threshold test

[0061] The crystal obtained in Example 1 was subjected to an r-on-1 irradiation scheme: energy was progressively increased for a single point on the optical element until damage occurred at that point. Test conditions: 1064 nm wavelength laser, 1 Hz operating frequency, 10 ns pulse width, adjustable laser energy from 1-250 mJ, and a lens focal length of f = 20 cm. The laser damage threshold of the methylphosphonate guanidine [C(NH2)3]2(CH3PO3) crystal of this invention was measured to be 326.8 MW / cm. 2 .

[0062] Stability test

[0063] The [C(NH2)3]2(CH3PO3) crystals prepared in Example 1 are characterized by their non-hygroscopic properties and stability in ambient air at room temperature. The thermal stability of [C(NH2)3]2(CH3PO3) was tested using thermogravimetric analysis and variable-temperature powder X-ray diffraction, and the results are as follows: Figure 7 , 8 As shown in the figure, the [C(NH2)3]2(CH3PO3) prepared in this invention only begins to decompose in a nitrogen atmosphere until the temperature reaches 262.8℃. The consistency between the diffraction pattern of variable-temperature powder X-ray diffraction at 180℃ and the simulated pattern based on single-crystal X-ray diffraction data indicates that the crystal of [C(NH2)3]2(CH3PO3) remains structurally stable in air at 180℃.

[0064] In summary, the methylphosphonate guanidine [C(NH2)3]2 (CH3PO3) of the present invention has excellent nonlinear optical properties and can be used as, but not limited to, nonlinear optical crystal materials, as well as in other optical devices and equipment.

[0065] The specific 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 exemplary 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 claims of the present invention.

Claims

1. A guanidine methylphosphonate compound, characterized in that, Its chemical formula is [C(NH2)3]2(CH3PO3).

2. The method for preparing the methylphosphonic acid guanidine compound according to claim 1, characterized in that, The preparation method includes the following steps: Method 1: Methylphosphonic acid, guanidine carbonate, and methanol are mixed and subjected to a solvothermal reaction to obtain the guanidine methylphosphonate compound; Method 2: Methylphosphonic acid, guanidine carbonate, lithium carbonate and water are mixed to obtain a reaction solution, and the guanidine methylphosphonate compound is obtained by slow evaporation.

3. The preparation method according to claim 2, characterized in that, The temperature of the solvothermal reaction is 100–150°C; the time of the solvothermal reaction is 1–60 hours. Preferably, the molar volume ratio of methylphosphonic acid, guanidine carbonate and methanol is (1-5) mmol:(1-5) mmol:(1-5) mL. Preferably, the evaporation temperature is room temperature to 50°C. Preferably, the molar volume ratio of methylphosphonic acid, guanidine carbonate, lithium carbonate and water is (5-15) mmol: (5-15) mmol: (10-20) mmol: (10-30) mL. Preferably, the pH value of the reaction solution is 8-9.

4. A guanidine methylphosphonate crystal, characterized in that, The chemical formula of the crystal is [C(NH2)3]2(CH3PO3).

5. The guanidine methylphosphonate crystal as described in claim 4, characterized in that, The cell parameters of the guanidine methylphosphonate crystal are as follows: α=γ=90°, β=119.324°(5), Preferably, the ultraviolet absorption cutoff edge of the guanidine methylphosphonate crystal is 207 nm. Preferably, the guanidine methylphosphonate crystal shown has an overtone intensity of 1.0 times that of KH2PO4 (KDP).

6. The application of the guanidine methylphosphonate crystal according to claim 4 or 5 as a nonlinear optical crystal material. Preferably, it is used as a nonlinear optical crystal material for solar-blind ultraviolet transmission.

7. A nonlinear optical crystal material, characterized in that, The material is the guanidine methylphosphonate crystal as described in claim 4 or 5.

8. The application of the guanidine methylphosphonate compound of claim 1 and / or the guanidine methylphosphonate crystal of claim 4 and / or the nonlinear optical crystal material of claim 7 in visible light frequency doubling laser output.

9. The application of the guanidine methylphosphonate compound of claim 1 and / or the guanidine methylphosphonate crystal of claim 4 and / or the nonlinear optical crystal material of claim 7 in all-solid-state lasers and optical parametric oscillators; for example, the all-solid-state laser is used in laser communication, laser processing, laser medicine, or semiconductor processing.

10. An optical device comprising the above-mentioned guanidine methylphosphonate compound and / or guanidine methylphosphonate crystal and / or nonlinear optical crystal material.

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