A deep ultraviolet-transmitting potassium scandium sulfate nonlinear optical crystal, its preparation method and application

Abstract

This invention belongs to the field of inorganic nonlinear optical materials technology, and particularly relates to a deep ultraviolet-transmitting potassium scandium sulfate nonlinear optical crystal, its preparation method, and its applications. The crystal has the chemical formula K3Sc(SO4)3, belongs to the monoclinic crystal system, and has different space groups at different temperatures: the space group below 200K is Pc (No. 7), and the space group above 202K is Ia (No. 9). The phase transition temperature of the crystal is between 200 and 202K. The potassium scandium sulfate nonlinear optical crystal of this invention has excellent nonlinear optical performance, with a powder frequency doubling intensity of approximately 1.62 times KDP, a wide transmission range, and a short deep ultraviolet cutoff edge (190 nm), and can achieve frequency-doubled laser output of Nd:YAG (1064 nm) lasers.

Description

Technical Field

[0001] This invention belongs to the field of inorganic nonlinear optical materials technology, and particularly relates to a deep ultraviolet-transmitting potassium scandium sulfate nonlinear optical crystal, its preparation method and application, especially its use as a nonlinear optical device. Background Technology

[0002] Deep ultraviolet (DUV) lasers possess high energy density and high spectral resolution, making them widely applicable in high-resolution spectroscopy, high-precision microprocessing, laser processing technology, biomedicine, and advanced scientific research equipment. DUV nonlinear optical crystals can generate coherent DUV light through frequency conversion, particularly the generation of second harmonics, playing a crucial role in all-solid-state lasers. A practical DUV nonlinear optical crystal must simultaneously meet stringent requirements, such as a non-centrosymmetric structure, a short DUV cutoff edge, and a large frequency doubling factor. However, current DUV nonlinear optical crystals, such as KBe₂BO₃F₂ (KBBF), NH₄Be₂BO₃F₂, and Na₄B₈O₉F₂, are limited in their application. 10 , RbMgCO3F, [C(NH2)3]3PO4∙2H2O, (NH4)2PO3F, (NH4)2B4SO 10 , Sr2(OH)3NO3, Ba2(OH)3NO3, NH4NaLi2(SO4)2, Ba3P3O 10 X (X=Cl, Br), etc., cannot meet all the above requirements. Therefore, the design and synthesis of novel inorganic deep ultraviolet nonlinear optical crystals remain a hot research topic in various countries. Summary of the Invention

[0003] To overcome the shortcomings of existing technologies, this invention provides a deep ultraviolet-transmitting potassium scandium sulfate nonlinear optical crystal, its preparation method, and its application. The potassium scandium sulfate nonlinear optical crystal exhibits low-temperature phase transition properties.

[0004] As previously stated, this invention provides a potassium scandium sulfate crystal with the chemical formula K3Sc(SO4)3, belonging to the monoclinic crystal system. The crystal has different space groups at different temperatures: below 200 K, the space group is [space group number missing]. Pc (No. 7), the space group above 202 K is Ia (No.9) The phase transition temperature of the crystal is 200~202K, and there is almost no significant thermal and volume change before and after the phase transition.

[0005] According to an embodiment of the present invention, the cell parameters of the potassium scandium sulfate crystal are as follows: a =8.8~9.3 Å, b =14.0~14.5 Å, c =8.8~9.3 Å,α = γ =90°, β =105~110°, V =1100~1200 Å 3 For example, when the temperature is 200 K, the cell parameters of the crystal are: a =9.1265(4) Å, b =14.3859(5) Å, c =9.0785(4) Å, α = γ =90°, β =108.539(5) °, V =1130.09(9) Å 3 When the temperature is 230 K, the cell parameters of the crystal are: a =9.0940(1)Å, b =14.4257(2) Å, c =9.1336(4) Å, α = γ =90°, β =108.343(2) °, V =1137.33(3) Å 3 .

[0006] According to an embodiment of the present invention, the potassium scandium sulfate crystal is a transparent crystal.

[0007] According to an embodiment of the present invention, the potassium scandium sulfate crystal has a substantially similar shape to... Figure 1 The crystal structure shown.

[0008] According to an embodiment of the present invention, the potassium scandium sulfate crystal is a nonlinear optical crystal.

[0009] According to an embodiment of the present invention, the potassium scandium sulfate crystal has a substantially similar shape to... Figure 2 The topographic diagram shown.

[0010] According to an embodiment of the present invention, the potassium scandium sulfate crystal is a single crystal.

[0011] According to an embodiment of the present invention, the single crystal size of the potassium scandium sulfate crystal is greater than 2 mm, preferably greater than 2.2 mm, for example 2.5 mm.

[0012] According to an embodiment of the present invention, the potassium scandium sulfate crystal has a substantially similar shape to... Figure 3 The X-ray powder diffraction pattern shown.

[0013] According to an embodiment of the present invention, the ultraviolet absorption edge of the potassium scandium sulfate crystal is 190 nm.

[0014] According to an embodiment of the present invention, the potassium scandium sulfate crystal has a substantially similar shape to... Figure 4 The optical transmittance in the ultraviolet region is shown.

[0015] According to an embodiment of the present invention, the potassium scandium sulfate crystals with a particle size of 212-270 μm, under 1064 nm laser irradiation, exhibit essentially the following properties: Figure 5 The second harmonic signal is shown.

[0016] According to an embodiment of the present invention, the octave intensity of the potassium scandium sulfate crystal is 1.62 times that of KH2PO4 (KDP).

[0017] According to an embodiment of the present invention, the potassium scandium sulfate crystal can achieve phase matching under 1064 nm laser irradiation, and has essentially the same properties as... Figure 6 The frequency doubling effect-particle size diagram is shown.

[0018] The present invention also provides a method for preparing the above-mentioned potassium scandium sulfate crystals, comprising the following steps: mixing a potassium-containing compound, a scandium-containing compound, sulfuric acid and water, and obtaining the potassium scandium sulfate crystals by hydrothermal reaction.

[0019] According to an embodiment of the present invention, the temperature is 200-300. o It is carried out under condition C.

[0020] According to an embodiment of the present invention, the hydrothermal reaction employs programmed temperature control: first heating, then maintaining a constant temperature, and finally cooling. For example, the temperature is increased from room temperature to 200-250°C within 60-240 minutes. o C, keep at a constant temperature for 12-120 hours, then add 1-10 o Cooling to room temperature at ℃ / hour; preferably, heating from room temperature to 230-240℃ within 100-140 minutes. o C, constant temperature for 72-120 hours, then 2-5 o Cool down to room temperature at C / hour.

[0021] According to an embodiment of the present invention, the molar volume ratio of the potassium compound, the scandium-containing compound, sulfuric acid and water is (1-8) mmol : (0.3-1.8) mmol : (0.1-1.0) mL : (0.5-4) mL, preferably the molar volume ratio of the potassium compound, the scandium-containing compound, sulfuric acid and water is (2-6) mmol : (0.5-1.2) mmol : (0.1-0.6) mL : (1-3) mL.

[0022] According to an embodiment of the present invention, the potassium-containing compound is one, two or more of potassium hydroxide, potassium nitrate, potassium sulfate, potassium chloride and potassium fluoride, for example, potassium hydroxide.

[0023] According to an embodiment of the present invention, the scandium-containing compound is one or a mixture of two of scandium oxide and scandium sulfate, for example, the scandium-containing compound is scandium oxide.

[0024] According to an embodiment of the present invention, the sulfuric acid is a sulfuric acid solution, for example, a concentrated sulfuric acid solution of 95.0% to 98.0%.

[0025] According to an embodiment of the present invention, the solvent is water.

[0026] According to an embodiment of the present invention, the molar volume ratio of potassium hydroxide, scandium oxide, and concentrated sulfuric acid is (1-8) mmol:(0.3-1.8) mmol:(0.1-1.0) mL, preferably, the molar volume ratio of potassium hydroxide, scandium oxide, and concentrated sulfuric acid is 4 mmol:0.8 mmol:0.3 mL.

[0027] According to an embodiment of the present invention, in this reaction system, the pH value of the reaction solution has an important influence on the synthesis of the crystal. A certain amount of acid-base adjuster should be added so that the final pH value of the reaction solution is between 1 and 4. Preferably, the added acid-base adjuster is sulfuric acid, and the final pH value of the reaction solution is 2-3.

[0028] According to an embodiment of the present invention, the volume ratio of sulfuric acid to water is (0.1-1.0) mL:(0.5-4) mL.

[0029] The present invention also provides a nonlinear optical crystal material, wherein the material contains at least the potassium scandium sulfate crystal.

[0030] The present invention also provides an application of the above-mentioned potassium scandium sulfate crystal as a nonlinear optical crystal material.

[0031] The present invention also provides the application of the potassium scandium sulfate in visible light frequency doubling laser output.

[0032] The present invention also provides the application of the potassium scandium sulfate crystal in all-solid-state lasers; for example, the all-solid-state lasers are used in laser communication, laser processing, laser medicine, and semiconductor processing.

[0033] The present invention also provides the application of the potassium scandium sulfate crystal in optoelectronic devices; preferably, the optical device is an optical parametric oscillator, an optical detector, etc., such as an ultra-low temperature switch, a sensitive sensor, etc.

[0034] Beneficial effects

[0035] 1. This invention provides the first-ever acquisition of potassium scandium sulfate (K3Sc(SO4)3) crystal and its application as a nonlinear optical crystal. This crystal exhibits excellent nonlinear optical properties, with a powder frequency doubling intensity of approximately 1.62 times the KDP, a wide transmission range, and a short deep ultraviolet cutoff edge (190 nm). It is also capable of achieving frequency-doubled laser output from Nd:YAG (1064 nm) lasers.

[0036] 2. The growth method of potassium scandium sulfate (K3Sc(SO4)3) crystal in this invention is simple, and the prepared crystals have high quality, large size, and a high laser damage threshold (165.12 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

[0037] Figure 1 This is a schematic diagram of the structure of potassium scandium sulfate K3Sc(SO4)3 crystals prepared in Example 1 of the present invention;

[0038] Figure 2 This is a photograph of the potassium scandium sulfate K3Sc(SO4)3 crystals grown according to the present invention.

[0039] Figure 3 Here is the X-ray powder diffraction pattern of potassium scandium sulfate (K3Sc(SO4)3) crystal prepared in Example 1 of this invention: Figure 3 (a) is the theoretically simulated X-ray powder diffraction pattern. Figure 3 (b) is the X-ray powder diffraction pattern of the experimental test;

[0040] Figure 4 This is an ultraviolet transmittance image of potassium scandium sulfate K3Sc(SO4)3 crystals prepared in Example 1 of this invention;

[0041] Figure 5 This is a second harmonic signal diagram of potassium scandium sulfate K3Sc(SO4)3 crystals with a particle size of 212-270 μm under 1064 nm laser irradiation.

[0042] Figure 6 This is a graph showing the relationship between the magnitude of the frequency doubling effect and the particle size of the potassium scandium sulfate (K3Sc(SO4)3) crystal prepared in Example 1 of this invention under 1064 nm laser irradiation. Detailed Implementation

[0043] 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.

[0044] Unless otherwise stated, the raw materials and reagents used in the following examples are commercially available products or can be prepared by known methods.

[0045] Example 1

[0046] 4.0 mmol of potassium hydroxide, 0.8 mmol of scandium oxide, 0.3 mL of concentrated sulfuric acid, and 1.0 mL of water were added to a polytetrafluoroethylene-lined stainless steel hydrothermal reactor. The reactor was then placed in a muffle furnace and heated from room temperature to 235°C over 120 minutes. o C, constant temperature for 96 hours, then at 4 o The rate was reduced to room temperature by C / h; the product was filtered and washed with anhydrous ethanol to obtain a large amount of pure potassium scandium sulfate K3Sc(SO4)3 crystals.

[0047] See Figure 1 The figure shown is a crystal structure diagram of potassium scandium sulfate K3Sc(SO4)3 crystal prepared in this embodiment. The upper figure is the crystal structure diagram at a temperature below 200 K, and the lower figure is the crystal structure diagram at a temperature above 202 K. There is almost no obvious thermal and volume change before and after the phase transition.

[0048] This sensitive and reversible transition between the two phases at ultra-low temperatures (-73℃) provides potential application prospects for potassium scandium sulfate (K3Sc(SO4)3) crystals in optoelectronic devices, such as ultra-low temperature switches and sensitive sensors (there is no obvious change in heat and volume between the two phase structures, but theoretical calculations of the structure show that the theoretical birefringence of the two phase structures is significantly different).

[0049] See Figure 2 The image shown is a physical picture of the potassium scandium sulfate K3Sc(SO4)3 crystal prepared in this embodiment. It has a single crystal structure, a large volume, and a side length of up to 2.5 mm.

[0050] See Figure 3 The figure shows the X-ray powder diffraction pattern of potassium scandium sulfate (K3Sc(SO4)3) crystal prepared in this embodiment. As can be seen from the figure, the powder X-ray diffraction (PXRD) experiment of K3Sc(SO4)3 crystal at room temperature... Figure 3 (a) Simulation with single-crystal X-ray diffraction Figure 3 (b) is consistent with the product, proving that the product is a pure phase.

[0051] Example 2

[0052] 6.0 mmol of potassium hydrogen sulfate, 1 mmol of scandium oxide, 0.1 mL of concentrated sulfuric acid, and 2.0 mL of water were added to a polytetrafluoroethylene-lined stainless steel hydrothermal reactor. The reactor was then placed in a muffle furnace and heated from room temperature to 230°C over 120 minutes. o C, constant temperature for 96 hours, then at 2.2 o The rate of C / h was reduced to room temperature; the product was filtered and washed with anhydrous ethanol to obtain a large amount of potassium scandium sulfate K3Sc(SO4)3 crystals.

[0053] Example 3

[0054] See Figure 4 The figure shows the transmittance and short deep ultraviolet cutoff edge of the potassium scandium sulfate (K3Sc(SO4)3) crystal prepared in Example 1 in the ultraviolet and deep ultraviolet bands. See also Figure 5 As shown, its doubling factor is approximately 1.62 times that of commercially available KDP (potassium dihydrogen phosphate) crystals. See also... Figure 6 As shown, the frequency doubling intensity of the crystal in Example 1 under 1064 nm laser irradiation continuously increases with the increase of particle size, and the intensity is higher than that of KDP, indicating that it can achieve phase matching.

[0055] Example 4 Laser Damage Threshold Test

[0056] The crystal obtained in Example 1 was subjected to an r-on-1 irradiation scheme: a point on the optical element was irradiated with progressively increasing energy until damage occurred at that point. Test conditions: 1064 nm wavelength laser, operating frequency 1 Hz, pulse width 10 ns, adjustable laser energy 1-250 mJ, lens focal length f=20 cm, and a relatively high laser damage threshold (165.12 MW / cm²). 2 ).

[0057] In summary, the potassium scandium sulfate K3Sc(SO4)3 of the present invention has excellent nonlinear optical properties and can be used as, but not limited to, a nonlinear optical material, as well as in other optical devices and equipment.

[0058] 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 potassium scandium sulfate crystal, characterized in that, The potassium scandium sulfate crystal has the chemical formula K3Sc(SO4)3 and belongs to the monoclinic crystal system. The potassium scandium sulfate crystal has different space groups at different temperatures: below 200 K, the space group is [space group number missing]. Pc (No. 7), the space group above 202 K is Ia (No. 9), the phase transition temperature of the potassium scandium sulfate crystal is 200~202K; The cell parameters of the potassium scandium sulfate crystal are as follows: a =8.8~9.3 Å, b =14.0~14.5 Å, c =8.8~9.3 Å, α = γ =90°, β =105~110°, V =1100~1200 Å 3 The potassium scandium sulfate crystal is a nonlinear optical crystal.

2. The potassium scandium sulfate crystal according to claim 1, characterized in that, When the temperature is 200 K, the cell parameters of the potassium scandium sulfate crystal are as follows: a =9.1265(4) Å, b =14.3859(5) Å, c =9.0785(4) Å, α = γ =90°, β =108.539(5) °, V =1130.09(9) Å 3 .

3. The potassium scandium sulfate crystal according to claim 1, characterized in that, When the temperature is 230 K, the cell parameters of the potassium scandium sulfate crystal are as follows: a =9.0940(1) Å, b =14.4257(2) Å, c =9.1336(4) Å, α = γ =90°, β =108.343(2) °, V =1137.33(3) Å 3 .

4. The potassium scandium sulfate crystal according to claim 1, characterized in that, The potassium scandium sulfate crystal has an X-ray powder diffraction pattern as shown in Figure 3.

5. The potassium scandium sulfate crystals according to any one of claims 1-4, characterized in that, The ultraviolet absorption cutoff edge of the potassium scandium sulfate crystal is 190 nm.

6. The potassium scandium sulfate crystals according to any one of claims 1-4, characterized in that, The potassium scandium sulfate crystal has a harmonic overtone intensity of 1.62 times that of KH2PO4 (KDP).

7. The potassium scandium sulfate crystals according to any one of claims 1-4, characterized in that, The potassium scandium sulfate crystal can achieve phase matching under 1064 nm laser irradiation.

8. A method for preparing potassium scandium sulfate crystals according to any one of claims 1-7, characterized in that, Includes the following steps: A reaction solution is prepared by mixing a potassium-containing compound, a scandium-containing compound, sulfuric acid, and water. The reaction solution is then subjected to a hydrothermal reaction to obtain the potassium scandium sulfate crystals.

9. The method for preparing potassium scandium sulfate crystals according to claim 8, characterized in that, The temperature of the hydrothermal reaction is 235°C. o C; The molar volume ratio of the potassium compound, scandium-containing compound, sulfuric acid and water is (1-8) mmol : (0.3-1.8) mmol : (0.1-1.0) mL : (0.5-4) mL.

10. The method for preparing potassium scandium sulfate crystals according to claim 8, characterized in that, The potassium-containing compound is one, two, or a mixture of more than one of potassium hydroxide, potassium nitrate, potassium sulfate, potassium chloride, and potassium fluoride. The scandium-containing compound is one or a mixture of two of scandium oxides and scandium sulfates.

11. The method for preparing potassium scandium sulfate crystals according to claim 10, characterized in that, The scandium-containing compound is scandium oxide.

12. The method for preparing potassium scandium sulfate crystals according to claim 11, characterized in that, The molar volume ratio of potassium hydroxide, scandium oxide, and concentrated sulfuric acid is (1-8) mmol : (0.3-1.8) mmol : (0.1-1.0) mL.

13. The method for preparing potassium scandium sulfate crystals according to any one of claims 8-12, characterized in that, After mixing potassium-containing compounds, scandium-containing compounds, sulfuric acid, and water to obtain a reaction solution, the following steps are also included: adding an acid-base adjuster to make the final pH value of the reaction solution between 1 and 4.

14. The method for preparing potassium scandium sulfate crystals according to any one of claims 8-12, characterized in that, The hydrothermal reaction employs programmed temperature control: the temperature is increased from room temperature to 200-250°C within 60-240 minutes. o C, keep at a constant temperature for 12-120 hours, then add 1-10 o Cool down to room temperature at C / hour.

15. A nonlinear optical crystal material, said material comprising at least the potassium scandium sulfate crystal according to any one of claims 1-7 or the potassium scandium sulfate crystal prepared by the method according to any one of claims 8-14.

16. The application of a potassium scandium sulfate crystal according to any one of claims 1-7 or a potassium scandium sulfate crystal prepared by the method according to any one of claims 8-14 as a nonlinear optical crystal material.

17. The application of a potassium scandium sulfate crystal according to any one of claims 1-7 or a potassium scandium sulfate crystal prepared by the method according to any one of claims 8-14 in optoelectronic devices.

18. The application according to claim 17, characterized in that, The optical devices are optical parametric oscillators and optical detectors.

19. The application according to claim 17, characterized in that, The optical devices are cryogenic switches and sensitive sensors.

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