Alkali metal difluoromalonate compounds, crystals thereof, and methods of making and using the same

Abstract

The present application relates to alkali metal difluoromalonate compound, its crystal and preparation method and application, the chemical formula of alkali metal difluoromalonate compound of the present application is A2(C3F2O4) nH2O, wherein, A is alkali metal, n is the integer of >0.It is colorless and transparent, not deliquescent in air, and has very strong phase matching ability;Its ultraviolet absorption edge is shorter than 250nm;The compound can produce 2 times frequency or 3 times frequency or 4 times frequency harmonic light output to the laser beam with wavelength of 1.064 μm, and can be used for preparing harmonic generator.

Description

Technical Field

[0001] This invention belongs to the field of optoelectronic functional materials technology, specifically relating to alkali metal difluoromalonate compounds, their crystals, preparation methods, and applications. Background Technology

[0002] The nonlinear optical effect of crystals refers to the transformation of a beam of light of a certain frequency into light of other frequencies through interaction with the medium.

[0003] Nonlinear optical crystals can perform frequency conversion on lasers through nonlinear optical effects, thus broadening the wavelength range of lasers and making them a core material for solid-state lasers. For example, borate nonlinear optical crystals such as BaB₂O₄ (BBO), LiB₃O₅ (LBO), KBa₂BO₃F₂ (KBBF), Sr₂Be₂B₂O₇ (SBBO), Ba₂Be₂B₂O₇ (TBO), K₂Al₂B₂O₇ (KABO), and BaAl₂B₂O₇ (BABO) have long been of interest to scientists due to their excellent linear and nonlinear optical properties. In fields such as laser-controlled nuclear fusion, optical information storage, and microfabrication, ultraviolet coherent light sources play a crucial role, and the key lies in developing ultraviolet nonlinear optical crystals with superior performance.

[0004] The anionic group of BBO crystal is (B3O6) with a conjugated large π bond. 3- Planar groups, due to the presence of conjugated large π bonds, exhibit extremely high polarizability anisotropy, which in turn leads to excessively high birefringence in the crystal (Δn = 0.12). This may cause walk-off effects, thereby affecting harmonic conversion efficiency and the quality of output light, thus limiting practical applications.

[0005] The anionic groups in LBO crystals can be considered as (B3O6) 3- One of the three-coordinate BO3 configurations in the group is replaced by a four-coordinate BO4 configuration, thus forming (B3O7). 5- This group avoids excessively high polarizability anisotropy because the conjugated large π bond is broken. However, due to (B3O7) 5- The groups in the LBO crystal are connected to each other at a 45° angle to the c-axis to form a helical chain, which makes it impossible to achieve parallel arrangement in the crystal lattice. This results in the crystal having excessively low birefringence (Δn = 0.04~0.05), which makes it difficult for the crystal to achieve phase matching in the ultraviolet region, greatly limiting its application range.

[0006] KBBF consists of planar groups (BO3). 3-Composed of tetrahedral BO3F groups, this crystal possesses a very short ultraviolet absorption edge (155 nm), a moderate birefringence (Δn = 0.07), and can achieve phase matching over a wide wavelength range, making it the only nonlinear optical crystal to date capable of practical applications. However, as a layered crystal, KBBF exhibits a much smaller interlayer binding energy than intralayer binding energy, resulting in a severe layered growth habit that poses significant challenges to the growth of large-size crystals.

[0007] Therefore, developing ultraviolet nonlinear optical crystal materials with excellent performance in all aspects has become one of the challenges and cutting-edge directions in the current research field of nonlinear optical materials. Summary of the Invention

[0008] To overcome the shortcomings of existing technologies, this invention provides an alkali metal difluoromalonate compound, its crystals, its preparation method, and its applications. The alkali metal difluoromalonate compound of this invention is colorless and transparent, does not deliquesce in air, and has extremely strong phase-matching ability; its ultraviolet absorption edge is shorter than 250 nm; the compound can generate harmonic light output at 2nd, 3rd, or 4th harmonics from a laser beam with a wavelength of 1.064 μm, and can be used to prepare harmonic generators.

[0009] This invention is achieved through the following technical solution:

[0010] An alkali metal difluoromalonate compound, wherein the chemical formula of the alkali metal difluoromalonate compound is A2(C3F2O4)·nH2O, wherein A is an alkali metal and n is an integer ≥0.

[0011] Specifically, A is K, Rb, or Cs; n is 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10.

[0012] Specifically, when A is K and n is 0, its chemical formula is K2(C3F2O4). The alkali metal difluoromalonate compound is a nonlinear optical crystal, lacking a center of symmetry, belonging to an orthorhombic crystal system, with space group Cmc21 and cell parameters of [missing information]. α=β=γ=90°, Z=4, unit cell volume is

[0013] Specifically, when A is Rb and n is 2, its chemical formula is Rb2(C3F2O4)·2H2O; the alkali metal difluoromalonate compound is a nonlinear optical crystal, lacking a center of symmetry, belonging to an orthorhombic crystal system, with space group Fdd2 and cell parameters of [missing information]. α=β=γ=90°, Z=8, unit cell volume is

[0014] Specifically, when A is Cs and n is 2, the alkali metal difluoromalonate compound with the chemical formula Cs2(C3F2O4)·2H2O is a nonlinear optical crystal, lacking a center of symmetry, belonging to an orthorhombic crystal system, with a crystal space group of Fdd2 and a unit cell parameter of [missing information]. α=β=γ=90°, Z=8, unit cell volume is

[0015] When A is K and n is 1, its chemical formula is K2(C3F2O4)·H2O, belonging to the orthorhombic crystal system, with crystal space group P212121 and unit cell parameters of [missing information]. α=β=γ=90°, Z=4, unit cell volume is

[0016] When A is Rb and n is 1, its chemical formula is Rb2(C3F2O4)·H2O, belonging to the monoclinic crystal system, with a crystal space group of P21 / c and a unit cell parameter of . α = 90°, β = 105.506°, γ = 90°, Z = 4, unit cell volume is

[0017] When A is Cs and n is 1, its chemical formula is Cs2(C3F2O4)·H2O, belonging to the monoclinic crystal system, with a crystal space group of P21 / c and a unit cell parameter of [missing information]. α = 90°, β = 105.730°, γ = 90°, Z = 4, unit cell volume is

[0018] Option 2)

[0019] A method for preparing an alkali metal difluoromalonate compound, comprising the following steps:

[0020] AOH·xH2O with a molar ratio greater than or equal to 1.5:1 (preferably (1.5~2):1) is reacted with C5H6F2O4 in deionized water at a temperature of 25~100℃ for more than 1 hour, and then evaporated at a temperature of 20℃~100℃ for 10~20 days to obtain the alkali metal difluoromalonate compound; wherein A is an alkali metal, and n is an integer ≥0. x in AOH·xH2O is also an integer ≥0.

[0021] Specifically, the molar ratio of AOH·xH2O to C5H6F2O4 is (1.8~2):1.

[0022] Specifically, the ratio of the total mass of AOH·xH2O and C5H6F2O4 to deionized water is 5–50 g: 100 ml. Preferably, it is 10–30 g: 100 ml.

[0023] The reaction temperature is 30–80°C, for example, 40°C or 70°C.

[0024] The evaporation temperature is 35–80℃. For example, 40℃ or 70℃.

[0025] Option 3)

[0026] The alkali metal difluoromalonate compound is used in the fabrication of lasers, ultraviolet harmonic generators, optical parametric amplifiers, and optical waveguides. The compound can generate harmonic light output at 2nd, 3rd, or 4th harmonics from a laser beam with a wavelength of 1.064 μm.

[0027] Option 4)

[0028] Optical parametric amplifier devices, including the aforementioned alkali metal difluoromalonate compound.

[0029] The beneficial effects of this invention are:

[0030] This invention prepares compounds with the chemical formula A2(C3F2O4)·nH2O, where A is an alkali metal and n is an integer ≥0, specifically alkali metal difluoromalonate compounds such as K2(C3F2O4) (hereinafter referred to as KCFO), Rb2(C3F2O4)·2H2O (hereinafter referred to as RCFO), and Cs2(C3F2O4)·2H2O (hereinafter referred to as CCFO) and their nonlinear optical crystals. This nonlinear optical crystal exhibits extremely strong phase-matching ability (measured using a powder harmonic generation method, its powder harmonic generation effect is approximately 4-5 times that of KH2PO4 (KDP)); its ultraviolet absorption edge is shorter than 250 nm. Furthermore, this nonlinear optical crystal can realize 2nd, 3rd, and 4th harmonic generators of Nd:YAG (λ=1.064μm). Moreover, this nonlinear optical crystal has a single-crystal structure, is colorless and transparent, and does not deliquesce in air. Therefore, it can be foreseen that A2(C3F2O4)·nH2O (specifically such as K2(C3F2O4), Rb2(C3F2O4)·2H2O, and Cs2(C3F2O4)·2H2O) will be widely used in various nonlinear optics fields and will open up nonlinear optics applications in the ultraviolet band. Attached Figure Description

[0031] Figure 1 This is a schematic diagram of the structure of a KCFO crystal.

[0032] Figure 2 This is a schematic diagram of the structure of RCFO and CCFO crystals (RCFO and CCFO are isomorphic compounds).

[0033] Figure 3 This is a schematic diagram of the structure of K2(C3F2O4)·H2O crystal.

[0034] Figure 4 This is a schematic diagram of the crystal structures of Rb2(C3F2O4)·H2O and Cs2(C3F2O4)·H2O (Rb2(C3F2O4)·H2O and Cs2(C3F2O4)·H2O are isomorphic compounds).

[0035] Figure 5 This is the X-ray diffraction pattern of KCFO single crystal after it has been ground into powder.

[0036] Figure 6 This is the X-ray diffraction pattern of RCFO single crystal after it has been ground into powder.

[0037] Figure 7 This is the X-ray diffraction pattern of CCFO single crystal after it has been ground into powder.

[0038] Figure 8 This is a typical schematic diagram of the nonlinear optical effects of KCFO, RCFO, and CCFO crystals when used as frequency doubling crystals. In this diagram, 1 is the laser, 2 is the incident laser beam, 3 is the single crystal after crystal post-processing and optical processing, 4 is the generated outgoing laser beam, and 5 is the filter.

[0039] Figure 9 This is a crystal photograph of Example 1.

[0040] Figure 10 This is a crystal photograph of Example 2.

[0041] Figure 11 This is a crystal photograph of Example 3. Detailed Implementation

[0042] 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.

[0043] Unless otherwise stated, the raw materials and reagents used in the following examples are commercially available products or can be prepared by known methods.

[0044] Example 1

[0045] Preparation of K2(C3F2O4) single crystals

[0046] The raw materials used are as follows:

[0047] 0.06 mol (3.44 g) of KOH

[0048] C5H6F2O4 0.03mol (5.04g)

[0049] H2O 50ml

[0050] The specific operating steps are as follows: Weigh the above raw materials according to the above dosage, put them into a 100ml beaker, place a magnetic stir bar inside, and put the beaker into a magnetic heating stirrer. While stirring, heat the beaker to 80℃. After the reaction is complete, place it in a 70℃ oven to evaporate, and obtain a K2(C3F2O4) single crystal with a size of 40×5×5mm.

[0051] (like Figure 9 (As shown)

[0052] The X-ray diffraction pattern of the single crystal after it has been ground into powder in this embodiment is as follows: Figure 5 As shown, its crystal structure diagram is as follows. Figure 1 As shown. It lacks a center of symmetry, belongs to the orthorhombic crystal system, has a space group of Cmc21, and its cell parameters are... α=β=γ=90°, Z=4, unit cell volume is

[0053] Example 2

[0054] Rb2(C3F2O4)·2H2O single crystals were prepared by aqueous solution method.

[0055] The raw materials used are as follows:

[0056] RbOH·H2O 0.06mol (7.23g)

[0057] C5H6F2O4 0.03mol (5.04g)

[0058] H2O 50ml

[0059] The specific operating steps are as follows: Weigh the above raw materials according to the above dosage, put them into a 100ml beaker, place a magnetic stir bar inside, and put the beaker in a magnetic stirrer. While stirring, heat the beaker to 40℃. After the reaction is complete, place it in a 40℃ oven to evaporate, and you will obtain Rb2(C3F2O4)·2H2O single crystals with a size of 7×10×5mm. (e.g.) Figure 10 (As shown)

[0060] The X-ray diffraction pattern of the single crystal after it has been ground into powder in this embodiment is as follows: Figure 6 As shown, its crystal structure diagram is as follows. Figure 2 As shown. The alkali metal difluoromalonate compound in this embodiment is a nonlinear optical crystal, lacking a center of symmetry, belonging to an orthorhombic crystal system, with space group Fdd2 and cell parameters of [missing information]. α=β=γ=90°, Z=8, unit cell volume is

[0061] Example 3

[0062] Cs2(C3F2O4)·2H2O single crystals were prepared by aqueous solution method.

[0063] The raw materials used are as follows:

[0064] CsOH·H2O 0.06mol (10.07g)

[0065] C5H6F2O4 0.03mol (5.04g)

[0066] H2O 50ml

[0067] The specific operating steps are as follows: Weigh the above raw materials according to the above dosage, put them into a 100ml beaker, place a magnetic stir bar inside, and put the beaker in a magnetic stirrer. While stirring, heat the beaker to 40℃. After the reaction is complete, place it in a 40℃ oven to evaporate, and you will obtain a Cs2(C3F2O4)·2H2O single crystal with a size of 12×12×7mm. (e.g.) Figure 11 (As shown)

[0068] The X-ray diffraction pattern of the single crystal after it has been ground into powder in this embodiment is as follows: Figure 7 As shown, its crystal structure diagram is as follows. Figure 2 As shown. This embodiment does not have a center of symmetry, belongs to an orthorhombic crystal system, has a crystal space group of Fdd2, and a unit cell parameter of... α=β=γ=90°, Z=8, unit cell volume is

[0069] Example 4

[0070] Rb2(C3F2O4)·2H2O single crystals were prepared by aqueous solution method.

[0071] The raw materials used are as follows:

[0072] RbOH·H2O 0.054mol (6.51g)

[0073] C5H6F2O4 0.03mol (5.04g)

[0074] H2O 50ml

[0075] The specific operating steps are as follows: Weigh the above raw materials according to the above dosage, put them into a 100ml beaker, place a magnetic stir bar inside, and put the beaker into a magnetic heating stirrer. While stirring, heat the beaker to 25℃. After the reaction is complete, place it in a 20℃ oven to evaporate, and you will get Rb2(C3F2O4)·2H2O single crystals.

[0076] The X-ray diffraction pattern of the single crystal after it has been ground into powder in this embodiment is as follows: Figure 6 As shown, its crystal structure diagram is as follows. Figure 2 As shown. The alkali metal difluoromalonate compound in this embodiment is a nonlinear optical crystal, lacking a center of symmetry, belonging to an orthorhombic crystal system, with space group Fdd2 and cell parameters of [missing information]. α=β=γ=90°, Z=8, unit cell volume is

[0077] Example 5

[0078] Preparation of Cs2(C3F2O4)·2H2O single crystals

[0079] The raw materials used are as follows:

[0080] CsOH·H2O 0.045mol (7.55g)

[0081] C5H6F2O4 0.03mol (5.04g)

[0082] H2O 50ml

[0083] The specific operating steps are as follows: Weigh the above raw materials according to the above dosage, put them into a 100ml beaker, place a magnetic stir bar inside, and put the beaker into a magnetic heating stirrer. While stirring, heat the beaker to 100℃. After the reaction is complete, place it in a 20℃ oven to evaporate, which yields the Cs2(C3F2O4)·2H2O single crystal.

[0084] The X-ray diffraction pattern of the single crystal after it has been ground into powder in this embodiment is as follows: Figure 7 As shown, its crystal structure diagram is as follows. Figure 2 As shown. This embodiment does not have a center of symmetry, belongs to an orthorhombic crystal system, has a crystal space group of Fdd2, and a unit cell parameter of... α=β=γ=90°, Z=8, unit cell volume is

[0085] Example 6

[0086] Preparation of K2(C3F2O4)·H2O

[0087] The raw materials used are as follows:

[0088] 0.06 mol (3.44 g) of KOH

[0089] C5H6F2O4 0.03mol (5.04g)

[0090] H2O 50ml

[0091] The specific operating steps are as follows: Weigh the above raw materials according to the above dosage, put them into a 100ml beaker, place a magnetic stir bar inside, and place the beaker in a magnetic stirrer. While stirring, heat the beaker to 80℃. After the reaction is complete, place it in a 30℃ oven to evaporate, obtaining K2(C3F2O4)·H2O single crystals.

[0092] The schematic diagram of the single crystal structure obtained in this embodiment is shown below. Figure 3 As shown. It lacks a center of symmetry, belongs to the orthorhombic crystal system, has a crystal space group of P212121, and a unit cell parameter of... α=β=γ=90°, Z=4, unit cell volume is

[0093] Example 7

[0094] Preparation of Rb2(C3F2O4)·H2O

[0095] The raw materials used are as follows:

[0096] RbOH·H2O 0.054mol (6.51g)

[0097] C5H6F2O4 0.03mol (5.04g)

[0098] H2O 50ml

[0099] The specific operating steps are as follows: Weigh the above raw materials according to the above dosage, put them into a 100ml beaker, place a magnetic stir bar inside, and put the beaker into a magnetic heating stirrer. While stirring, heat the beaker to 25℃. After the reaction is complete, place it in a 100℃ oven to evaporate, thus obtaining Rb2(C3F2O4)·H2O single crystals.

[0100] A schematic diagram of the single crystal structure obtained in this embodiment is shown below. Figure 4 As shown. It belongs to the monoclinic crystal system, with crystal space group P21 / c and cell parameters of... α = 90°, β = 105.506°, γ = 90°, Z = 4, unit cell volume is

[0101] Example 8

[0102] Preparation of Cs2(C3F2O4)·H2O

[0103] The raw materials used are as follows:

[0104] CsOH·H2O 0.045mol (7.55g)

[0105] C5H6F2O4 0.03mol (5.04g)

[0106] H2O 100ml

[0107] The specific operating steps are as follows: Weigh the above raw materials according to the above dosage, put them into a beaker, place a magnetic stir bar inside, and place the beaker in a magnetic heating stirrer. While stirring, heat the beaker to 100°C. After the reaction is complete, place it in a 100°C oven to evaporate, which yields the Cs2(C3F2O4)·H2O single crystal.

[0108] A schematic diagram of the single crystal structure obtained in this embodiment is shown below. Figure 4 As shown. It belongs to the monoclinic crystal system, with crystal space group P21 / c and cell parameters of... α = 90°, β = 105.730°, γ = 90°, Z = 4, unit cell volume is

[0109] The K2(C3F2O4), Rb2(C3F2O4)·2H2O and Cs2(C3F2O4)·2H2O crystals obtained in the above embodiments were processed, cut, oriented, polished, and then placed in... Figure 8 At position 3 in the device shown, at room temperature, using a Q-switched Nd:YAG laser as the input light source with an incident wavelength of 1064 nm, a significant 532 nm frequency-doubled green light output was observed, with an output intensity approximately 4-5 times that of KDP under the same conditions. Specifically, the output intensity of K2(C3F2O4) crystal is approximately 4 times that of KDP under the same conditions, the output intensity of Rb2(C3F2O4)·2H2O crystal is approximately 5 times that of KDP under the same conditions, and the output intensity of Cs2(C3F2O4)·2H2O crystal is approximately 5 times that of KDP under the same conditions.

[0110] Therefore, the alkali metal difluoromalonate compound of the present invention can be used to prepare lasers, ultraviolet harmonic generators, optical parametric amplifiers, and optical waveguides. The compound can generate harmonic light output at 2nd, 3rd, or 4th harmonics from a laser beam with a wavelength of 1.064 μm.

[0111] The embodiments of the present invention have been described above. However, the present invention is not limited to the above embodiments. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. An alkali metal difluoromalonate compound, characterized in that: The chemical formula of the alkali metal difluoromalonate compound is A2(C3F2O4)·nH2O, where A is an alkali metal and n is an integer ≥0; A is K, Rb, or Cs; n is 0, 1, or 2; When A is K and n is 0, its chemical formula is K2 (C3F2O4). The alkali metal difluoromalonate compound is a nonlinear optical crystal, lacks a center of symmetry, belongs to an orthorhombic crystal system, and has a space group of [missing information]. Cmc2 1 The unit cell parameters are a = 5.8014(5) Å, b = 14.6740(16) Å, c = 7.9473(8) Å, α = β = γ = 90°, Z = 4, unit cell volume is V = 676.55 Å 3 ; When A is Rb and n is 2, its chemical formula is Rb2(C3F2O4)·2H2O; the alkali metal difluoromalonate compound is a nonlinear optical crystal, lacks a center of symmetry, belongs to an orthorhombic crystal system, and has a space group of Fdd2 The unit cell parameters are a = 20.6926(3) Å, b = 15.8443 (2) Å, c = 5.0537(1) Å, α = β = γ = 90°, Z = 8, unit cell volume is V = 1656.90 Å 3 ; When A is Cs and n is 2, its chemical formula is Cs2(C3F2O4)·2H2O. The alkali metal difluoromalonate compound is a nonlinear optical crystal, lacks a center of symmetry, belongs to an orthorhombic crystal system, and has a space group of [space group missing]. Fdd2 The unit cell parameters are a = 16.5741(5) Å, b = 21.4724 (6) Å, c = 5.3244(2) Å, α = β = γ = 90°, Z = 8, unit cell volume is V = 1894.88 Å 3 ; When A is Rb and n is 1, its chemical formula is Rb2(C3F2O4)·H2O, belonging to the monoclinic crystal system, and its crystal space group is [missing information]. P2 1 / c The unit cell parameters are a = 8.6165(6) Å, b = 11.5028 (6) Å, c = 8.2278(5) Å, α = 90°, β = 105.506°, γ = 90°, Z = 4, unit cell volume is V = 785.81 Å 3 ; When A is Cs and n is 1, its chemical formula is Cs2(C3F2O4)·H2O, belonging to the monoclinic crystal system, and its crystal space group is [missing information]. P2 1 / c The unit cell parameters are a = 8.8730(4) Å, b = 11.3248 (5) Å, c = 8.9516(4) Å, α = 90°, β = 105.730° γ = 90°, Z = 4, unit cell volume is V = 865.81 Å 3 .

2. A method for preparing an alkali metal difluoromalonate compound, characterized in that: Includes the following steps: AOH·xH2O with a molar ratio greater than or equal to 1.5:1 and C5H6F2O4 are reacted in deionized water at a temperature of 25~100℃ for more than 1 hour, and then evaporated at a temperature of 20℃-100℃ for 10-20 days to obtain the alkali metal difluoromalonate compound A2(C3F2O4)·nH2O as described in claim 1; wherein A is an alkali metal and n is an integer ≥0.

3. The method for preparing the alkali metal difluoromalonate compound according to claim 2, characterized in that: The molar ratio of AOH·xH2O to C5H6F2O4 is (1.8~2):1; The ratio of the total mass of AOH·xH2O and C5H6F2O4 to deionized water is 5~50g : 50~100ml; The reaction temperature is 30~80℃; The evaporation temperature is 35~80℃.

4. The use of the alkali metal difluoromalonate compound as described in claim 1, characterized in that: The aforementioned alkali metal difluoromalonate compound is used to prepare lasers, ultraviolet harmonic generators, optical parametric amplifiers, and optical waveguide devices.

5. An optical parametric amplifier device, characterized in that: Includes the alkali metal difluoromalonate compound as described in claim 1.

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