A second-order nonlinear optical potassium cadmium fluoroborate crystal material, a preparation method and application thereof
By preparing potassium fluoroborate cadmium crystal material, the performance limitations of existing second-order nonlinear optical crystal materials have been overcome, enabling efficient and low-cost laser frequency conversion and optoelectronic modulation applications, and providing a method for preparing high-quality crystals.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- HEFEI UNIV
- Filing Date
- 2026-05-25
- Publication Date
- 2026-07-21
AI Technical Summary
Existing second-order nonlinear optical crystal materials such as KDP, KTP and β-BBO have their own limitations in performance, such as high damage threshold, limited resistance to optical damage or difficulty in crystal growth. Traditional high-temperature solid-state methods are energy-intensive and difficult to control crystal morphology and purity, making it difficult to meet the requirements for the preparation of high-quality crystals.
A second-order nonlinear optical potassium fluoroborate cadmium crystal material, KCdFBO3H, was prepared by hydrothermal reaction. Using the planar triangle of BO3 and the triangular bipyramidal structure of CdO3F2 as basic structural units, a one-dimensional chain and a three-dimensional open framework were formed. Potassium ions filled the channels to prepare a triangular prism-shaped crystal for laser frequency conversion and photoelectric modulation.
A potassium fluoroborate crystal with excellent second-order nonlinear optical properties was achieved. The powder frequency doubling intensity is about 5.1 times that of KDP. It has phase matching conditions, high crystallinity, is environmentally friendly, and the raw materials are readily available and low in cost, making it suitable for industrial applications.
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Abstract
Description
Technical Field
[0001] This invention relates to the field of inorganic nonlinear optical materials technology, and in particular to a second-order nonlinear optical potassium fluoroborate cadmium crystal material, its preparation method, and its application. Background Technology
[0002] Nonlinear optical materials are key functional materials in fields such as laser frequency conversion, photoelectric modulation, and optical information processing. With the rapid development of laser technology, the research and development of novel second-order nonlinear optical crystals with excellent comprehensive performance has become an important research direction.
[0003] Currently, commercially available KH₂PO₄ (KDP), KTiOPO₄ (KTP), and β-BaB₂O₄ (β-BBO) still have certain limitations: KDP has a high damage threshold but a low nonlinear coefficient; KTP has a good frequency doubling effect but limited resistance to photodamage; β-BBO has excellent UV transmittance but is difficult to grow and is prone to deliquescence. Meanwhile, traditional high-temperature solid-state methods are energy-intensive and difficult to control in terms of crystal morphology and purity, making it difficult to meet the requirements for preparing high-quality crystals.
[0004] In recent years, fluoroborooxyate systems have attracted much attention due to their structural diversity and excellent optical transmittance in the ultraviolet and deep ultraviolet regions, while research on cadmium-containing fluoroborooxyates is still relatively insufficient. Summary of the Invention
[0005] Based on this, the purpose of this invention is to provide a second-order nonlinear optical potassium fluoroborate cadmium crystal material, its preparation method and application. This second-order nonlinear optical potassium fluoroborate cadmium crystal material has excellent second-order nonlinear optical properties, and its powder frequency doubling intensity is about 5.1 times that of KDP. It can achieve phase matching and has application potential in laser frequency conversion, optoelectronic modulation and other fields.
[0006] To achieve the above objectives, the present invention adopts the following technical solution: This invention provides a second-order nonlinear optical potassium fluoroborate crystal material, wherein the chemical formula of the potassium fluoroborate crystal material is KCdFBO3H, it belongs to the hexagonal crystal system, and its space group is [missing information]. P- 6 c 2 (No. 188), unit cell parameters are: a = b =5.01710(10)Å, c = 8.3553(2) Å, α = β =90°, γ =120° V =182.137(8) Å 3 , Z = 2.
[0007] As a further improvement to the above-described scheme of the present invention, the potassium fluoroborate cadmium crystal material uses BO3 planar triangles and CdO3F2 triangular bipyramids as basic structural units. Each BO3 planar triangle is connected to three CdO3F2 triangular bipyramids, and each CdO3F2 triangular bipyramid is connected to three BO3 planar triangles. The CdO3F2 triangular bipyramids share F atom vertices along the unit cell. a shaft or b Axial connections form a one-dimensional infinite chain [CdO3F2]. ∞ Each chain is bridged by oxygen atoms of the BO3 group to form a three-dimensional open framework, and potassium ions fill the pores of the three-dimensional open framework.
[0008] As a further improvement to the above-mentioned solution of the present invention, the potassium fluoroborate cadmium crystal material has a triangular prism block structure.
[0009] The present invention also provides a method for preparing the second-order nonlinear optical potassium fluoroborate cadmium crystal material as described above, which includes the following steps: adding boric acid, cadmium oxide, potassium fluoride, potassium fluoroborate and potassium hydroxide into ultrapure water, performing a hydrothermal reaction at a constant temperature, separating, washing, and drying to obtain the second-order nonlinear optical potassium fluoroborate cadmium crystal material.
[0010] As a further improvement to the above-mentioned scheme of the present invention, the molar ratio of boric acid, cadmium oxide, potassium fluoride, potassium fluoroborate, and potassium hydroxide is 7:1:5:1:6.
[0011] As a further improvement to the above-mentioned scheme of the present invention, the isothermal hydrothermal reaction is first heated to 220±1 ℃ and kept at a constant temperature for 48 hours, and then cooled to 70 ℃ to end the reaction.
[0012] As a further improvement to the above-mentioned solution of the present invention, the heating rate is 10℃ / min and the cooling rate is 1.7±0.1℃ / h.
[0013] As a further improvement to the above-mentioned solution of the present invention, the washing process involves soaking and washing in boiling water at 100°C to remove impurities.
[0014] The present invention also provides an application of the second-order nonlinear optical potassium fluoroborate crystal material as described above in laser frequency converters and optoelectronic modulators.
[0015] Compared with the prior art, the present invention has the following beneficial effects: The second-order nonlinear optical potassium fluoroborate cadmium crystal material provided by this invention has a novel structure, crystallizes in a non-centrosymmetric space group, has excellent second-order nonlinear optical properties, and its powder frequency doubling intensity is about 5.1 times that of KDP. It can achieve phase matching and has application potential in laser frequency conversion, optoelectronic modulation and other fields.
[0016] This invention employs a mild hydrothermal process to prepare second-order nonlinear optical potassium fluoroborate cadmium crystal materials. The conditions are controllable and environmentally friendly, the products have high crystallinity and good batch repeatability, the raw materials are readily available and the cost is low, and the process is simple. It has the potential for scale-up preparation and industrial application, and is of great significance for enriching material systems and expanding device applications. Attached Figure Description
[0017] Figure 1 Scanning electron microscope (SEM) image of the second-order nonlinear optical potassium fluoroborate cadmium crystal material prepared in an embodiment of the present invention; Figure 2 This is a molecular structure diagram of the second-order nonlinear optical potassium fluoroborate cadmium crystal material prepared in the embodiments of the present invention; Figure 3 This is the powder X-ray diffraction (XRD) pattern of the second-order nonlinear optical potassium fluoroborate cadmium crystal material prepared in the embodiments of the present invention; Figure 4 This is the electron energy spectrum (EDS) of the second-order nonlinear optical potassium fluoroborate cadmium crystal material prepared according to an embodiment of the present invention; Figure 5 This is the UV-Vis diffuse reflectance image of the second-order nonlinear optical potassium fluoroborate crystal material prepared according to the embodiments of the present invention; Figure 6 This is a diagram showing the second-order nonlinear optical effect (SHG) and phase matching of the potassium fluoroborate cadmium crystal material prepared according to an embodiment of the present invention. Detailed Implementation
[0018] To facilitate understanding of the present invention, a more comprehensive description will be given below with reference to specific embodiments. However, the present invention can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided to provide a more thorough and complete understanding of the disclosure of the present invention.
[0019] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used herein in the description of the invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention.
[0020] This embodiment proposes a second-order nonlinear optical potassium fluoroborate cadmium crystal material, the preparation method of which includes the following steps: boric acid, cadmium oxide, potassium fluoride, potassium fluoroborate and potassium hydroxide are weighed in a millimolecular ratio of 7:1:5:1:6 and added to a polytetrafluoroethylene-lined reactor. 0.1 mL of ultrapure deionized water is added, and the mixture is stirred evenly and then sealed in a stainless steel high-pressure reactor. The reactor is placed in a programmable temperature controlled furnace, and the temperature is increased to 220±1℃ at a heating rate of 10℃ / min for 120 min. The temperature is maintained at 220±1℃ for 48 h. The temperature is then decreased to 70℃ at a cooling rate of 1.7℃ / h, and the reaction is stopped. After natural cooling to room temperature, the reactor is opened, the solid and liquid are separated, and the obtained crystals are washed with boiling water at 100℃ to remove impurities. After drying, potassium fluoroborate cadmium crystals are obtained.
[0021] Figure 1 Here is a SEM image of the potassium fluoroborate cadmium crystals prepared in this embodiment. Figure 1 It can be seen that the potassium fluoroborate cadmium crystals obtained in this embodiment have a regular triangular prism morphology.
[0022] The potassium fluoroborate cadmium crystal obtained in this embodiment has the chemical formula KCdFBO3H. It is a colorless, transparent, triangular prism-shaped blocky crystal, belonging to the hexagonal crystal system, with a space group of [space group missing]. P- 6 c 2 (No. 188), unit cell parameters are: a=b= 5.01710(10)Å, c =8.3553(2)Å, α = β = 90° γ =120° V =182.137(8)Å 3 , Z =2. For example... Figure 2 As shown, potassium fluoroborate crystals use BO3 planar triangles and CdO3F2 triangular bipyramids as basic structural units. Each BO3 planar triangle is connected to three CdO3F2 triangular bipyramids, and each CdO3F2 triangular bipyramid is connected to three BO3 planar triangles. The CdO3F2 triangular bipyramids share F atom vertices along the unit cell. a shaft or b Axial connections form a one-dimensional infinite chain [CdO3F2]. ∞ Each chain is bridged by oxygen atoms of the BO3 group to form a three-dimensional open framework, and potassium ions fill the channels of the three-dimensional open framework to balance the charge.
[0023] Figure 3 The XRD pattern of potassium fluoroborate cadmium crystals prepared in this embodiment is shown below. Figure 3It can be seen that the results are in good agreement with the single-crystal simulation spectrum, indicating that the product obtained in this embodiment has a pure phase and high crystallinity.
[0024] Figure 4 The electron energy spectrum of the potassium fluoroborate crystals prepared in this embodiment is shown below. Figure 4 The results show that the proportions of each element are consistent with the chemical formula, further confirming the accuracy of the material composition.
[0025] Figure 5 The image shows the diffuse ultraviolet reflectance spectrum of the potassium fluoroborate crystals prepared in this embodiment. Figure 5 This indicates that the band gap of the potassium fluoroborate crystals prepared in this embodiment is approximately 3.19 eV.
[0026] Figure 6 The diagram shows the second-order nonlinear optical effect and phase-matching of the potassium fluoroborate crystal prepared in this embodiment. Figure 6 The results show that the material has excellent second-order nonlinear optical properties, with a second harmonic generation (SHG) intensity 5.1 times that of KDP, and meets the phase matching condition.
[0027] Unless otherwise specified, the experimental methods used in this embodiment are conventional methods in the field; all reagents used are commercially available products.
[0028] The potassium fluoroborate prepared by this invention can be used as a second-order nonlinear optical material for frequency conversion in all-solid-state lasers, such as frequency doubling, sum frequency, and difference frequency conversion.
[0029] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.
[0030] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these all fall within the protection scope of the present invention. Therefore, the protection scope of this invention patent should be determined by the appended claims.
Claims
1. A second-order nonlinear optical potassium fluoroborate cadmium crystal material, characterized in that, The potassium fluoroborate cadmium crystal material has the chemical formula KCdFBO3H, belongs to the hexagonal crystal system, and has the space group [missing information]. P- 6 c 2 (No. 188), unit cell parameters are: a=b= 5.01710(10)Å, c =8.3553(2)Å, α = β =90°, γ =120° V =182.137(8)Å 3 , Z =2.
2. The second-order nonlinear optical potassium fluoroborate crystal material according to claim 1, characterized in that, The potassium fluoroborate cadmium crystal material uses BO3 planar triangles and CdO3F2 triangular bipyramids as basic structural units. Each BO3 planar triangle is connected to three CdO3F2 triangular bipyramids, and each CdO3F2 triangular bipyramid is connected to three BO3 planar triangles. The CdO3F2 triangular bipyramids are connected along the a-axis or b-axis of the unit cell by sharing F atom vertices to form a one-dimensional infinite chain [CdO3F2]. ∞ Each chain is bridged by oxygen atoms of the BO3 group to form a three-dimensional open framework, and potassium ions fill the pores of the three-dimensional open framework.
3. The second-order nonlinear optical potassium fluoroborate crystal material according to claim 1, characterized in that, The potassium fluoroborate cadmium crystal material has a triangular prism block structure.
4. A method for preparing a second-order nonlinear optical potassium fluoroborate cadmium crystal material as described in any one of claims 1-3, characterized in that, It includes the following steps: Boric acid, cadmium oxide, potassium fluoride, potassium fluoroborate, and potassium hydroxide were added to ultrapure water and subjected to a constant-temperature hydrothermal reaction. The mixture was then separated, washed, and dried to obtain a second-order nonlinear optical potassium fluoroborate crystal material.
5. The method for preparing the second-order nonlinear optical potassium fluoroborate cadmium crystal material according to claim 4, characterized in that, The molar ratio of boric acid, cadmium oxide, potassium fluoride, potassium fluoroborate, and potassium hydroxide is 7:1:5:1:
6.
6. The method for preparing second-order nonlinear optical potassium fluoroborate cadmium crystal material according to claim 4, characterized in that, The constant-temperature hydrothermal reaction is first heated to 220±1℃ and kept at that temperature for 48 hours, then cooled to 70℃ to end the reaction.
7. The method for preparing the second-order nonlinear optical potassium fluoroborate cadmium crystal material according to claim 6, characterized in that, The heating rate is 10℃ / min, and the cooling rate is 1.7±0.1℃ / h.
8. The method for preparing second-order nonlinear optical potassium fluoroborate cadmium crystal material according to claim 4, characterized in that, The washing process involves soaking the item in boiling water at 100°C to remove impurities.
9. The application of a second-order nonlinear optical potassium fluoroborate crystal material as described in any one of claims 1-3 in laser frequency converters and optoelectronic modulators.