Second-order nonlinear optical material zinc fluoborate as well as preparation method and application thereof

Abstract

The invention relates to the technical field of second-order nonlinear optical materials, in particular to a second-order nonlinear optical material zinc fluoroborate as well as a preparation method and application thereof. The chemical formula of the zinc fluoborate is KZnBO3FH, and the crystallographic characteristics are as follows: the zinc fluoborate belongs to a hexagonal system, the space group is P-6c2, and the crystal unit cell parameters are as follows: alpha is equal to 90 degrees, beta is equal to 90 degrees, and gamma is equal to 120 degrees; z = 2. According to the zinc fluoborate salt, a hydrothermal synthesis process is adopted, boric acid and water are used as solvents, zinc fluoride, potassium carbonate and potassium fluoborate react for 12-48 hours at the temperature of 200-220 DEG C under the condition of a potassium hydroxide strong alkali medium, and finally the potassium zinc fluoborate which has a regular triangular prism shape and is crystallized in a non-centered space group is obtained. The potassium zinc fluoborate shows excellent second-order nonlinear optical characteristics, the powder frequency-doubled effect intensity of the potassium zinc fluoborate can reach 7 times that of a KH2PO4 (KDP) reference material, and meanwhile, the potassium zinc fluoborate has a 379nm short-wave ultraviolet absorption cutoff edge and shows excellent wide-spectrum light transmission performance.

Description

Technical Field

[0001] This invention relates to the field of second-order nonlinear optical material zinc fluoroborate salt technology, specifically to a second-order nonlinear optical material zinc fluoroborate salt, its preparation method and application. Background Technology

[0002] Nonlinear optical (NLO) crystals are an important component in the development of modern solid-state lasers. They effectively extend the wavelength range of solid-state lasers, finding irreplaceable applications in cutting-edge fields such as optoelectronic communication, laser precision machining, and biomedical imaging. Generally, nonlinear optical materials can be categorized based on their light transmission range into infrared (IR), visible (vis), ultraviolet (UV), and deep ultraviolet (DUV, below 200nm) NLO crystal materials. Many nonlinear optical materials include β-BaB₂O₄ (β-BBO), LiB₃O₅ (LBO), and CsLiB₆O₄. 10 Zinc fluoroborate (CLBO), CsB3O5 (CBO), KTiOPO4, KBa2BO3F2 (KBBF), and ZnGeP2 have been discovered and put into commercial use. Among them, borates have very important applications in nonlinear optical materials due to their structural diversity and excellent performance characterization. Meanwhile, introducing fluorine atoms into borates can cause a blue shift of the ultraviolet absorption cutoff edge of the compound towards shorter wavelengths, effectively reducing the electronic polarizability of the material and thus obtaining zinc fluoroborate salts with superior performance.

[0003] Research has revealed that the synthesis methods for borates mainly include high-temperature solid-state methods, hydrothermal / solvothermal methods, precursors, and fluxes. However, these methods are complex, costly, and difficult to scale up for application. Summary of the Invention

[0004] The purpose of this invention is to solve the problems of complex and high cost in the synthesis process of borates in the prior art, and to propose a new second-order nonlinear optical material, zinc fluoroborate.

[0005] The present invention achieves the above objectives through the following technical solutions:

[0006] First, this invention provides a second-order nonlinear optical material, zinc fluoroborate salt. The zinc fluoroborate salt is potassium zinc fluoroborate, with the chemical formula KZnFBO3H, belonging to the hexagonal crystal system, with triangular prism-shaped crystals, space group P-6c2, and unit cell parameters of [missing information]. α=90°, β=90°, γ=120°; Z = 2.

[0007] As a further improvement of the present invention, the basic structural unit of the aluminum phosphate salt is composed of isolated BO3 planar triangular anionic coordinating groups and ZnO3F2 hexahedrons; each BO3 planar triangle connects to three ZnO3F2 hexahedrons, and each ZnO3F2 hexahedron connects to three BO3 planar triangles. The ZnO3F2 hexahedrons are connected by sharing F atom vertices to form a one-dimensional chain structure [ZnO3F2] extending along the a-axis or b-axis of the unit cell. ∞ The one-dimensional chain is further bridged by shared oxygen atoms through BO3 groups to form a three-dimensional open framework structure, and potassium ions fill the channels.

[0008] Second, the present invention provides a method for preparing the above-mentioned second-order nonlinear optical material zinc fluoroborate, comprising the following steps:

[0009] (1) Place boric acid, zinc fluoride, potassium carbonate, potassium fluoroborate and potassium hydroxide raw materials in a polytetrafluoroethylene reaction liner, add ultrapure deionized water and stir evenly, then seal in a reaction vessel.

[0010] (2) Place the reactor in the furnace, heat it and react at a constant temperature. After the set reaction time, gradually cool it down. After the reaction is completed, turn off the furnace and let it cool naturally to room temperature.

[0011] (3) Remove the naturally cooled liner from the reactor, wash the solid mixture in the liner repeatedly with boiling water and dry it to finally obtain the second-order nonlinear optical material zinc fluoroborate salt.

[0012] As a further improvement of the present invention, in step (1), the molar ratio of boric acid, zinc fluoride, potassium carbonate, potassium fluoroborate and potassium hydroxide is 4:1:1:1:5.

[0013] As a further improvement of the present invention, in step (2), the temperature is first heated from room temperature to 220°C at a rate of 10°C / min for 120 min, and then maintained at a constant temperature of 220±1°C for 12h-48h for hydrothermal reaction.

[0014] As a further improvement of the present invention, in step (2), the gradient cooling is to terminate the reaction by reducing the temperature from 220℃ to 70℃ at a gradient cooling rate of 1.8℃ / h after a constant temperature reaction of 12h-48h.

[0015] Third, the present invention provides an application of the above-mentioned second-order nonlinear optical material zinc fluoroborate salt in second-order nonlinear optical materials.

[0016] The beneficial effects of this invention are as follows:

[0017] (1) The present invention obtains a novel zinc fluoroborate salt with a non-central space group by hydrothermal synthesis. The zinc fluoroborate salt has excellent second-order nonlinear optical properties and its second harmonic generation (SHG) intensity reaches 1.8 times that of KH2PO4 (KDP).

[0018] (2) The zinc fluoroborate salt prepared by this invention is a potential second-order nonlinear optical material that can be used in laser frequency conversion, optical communication, integrated circuits, sensors, biomedicine and other fields.

[0019] (3) The operation process of this invention is simple and convenient, highly operable, low cost, mild reaction temperature, energy saving and environmental protection, and high target yield. The ultraviolet cutoff edge of this novel zinc potassium fluoroborate is about 379 nm. Attached Figure Description

[0020] Figure 1 This is a molecular crystal structure diagram of the zinc fluoroborate salt prepared in this invention;

[0021] Figure 2 This is a scanning electron microscope (SEM) image of the zinc fluoroborate salt prepared in this invention;

[0022] Figure 3 This is the XRD pattern of the zinc fluoroborate salt prepared in this invention;

[0023] Figure 4 This is the EDS electronic spectrum of the zinc fluoroborate salt prepared in this invention;

[0024] Figure 5 This is the ultraviolet diffuse reflectance spectrum of the zinc fluoroborate salt prepared in this invention;

[0025] Figure 6 This is a diagram showing the second-order nonlinear optical effect and phase matching of the zinc fluoroborate salt prepared in this invention. Detailed Implementation

[0026] The subject matter described herein will now be discussed with reference to exemplary embodiments. It should be understood that these embodiments are discussed only to enable those skilled in the art to better understand and implement the subject matter described herein, and changes may be made to the function and arrangement of the elements discussed without departing from the scope of this specification.

[0027] At least one embodiment of the present invention discloses a second-order nonlinear optical material, zinc fluoroborate. The second-order nonlinear optical material, zinc fluoroborate, is potassium zinc fluoroborate, with the chemical formula KZnFBO3H. It belongs to the hexagonal crystal system, has a triangular prism-shaped crystal, a space group of P-6c2, and a unit cell parameter of [missing information]. α=90°, β=90°, γ=120°; Z = 2.

[0028] The basic structural unit of the second-order nonlinear optical material zinc fluoroborate salt consists of isolated BO3 planar triangular anionic coordinating groups and ZnO3F2 hexahedrons. Each BO3 planar triangle connects to three ZnO3F2 hexahedrons, and each ZnO3F2 hexahedron connects to three BO3 planar triangles. The ZnO3F2 hexahedrons are connected by sharing F atom vertices to form a one-dimensional chain structure [ZnO3F2] extending along the a-axis or b-axis of the unit cell. ∞ The one-dimensional chain is further bridged by shared oxygen atoms through BO3 groups to form a three-dimensional open framework structure, and potassium ions fill the channels to balance the charge.

[0029] At least one embodiment of the present invention discloses a method for preparing a second-order nonlinear optical material, zinc fluoroborate, comprising the following steps:

[0030] (1) Place boric acid, zinc fluoride, potassium carbonate, potassium fluoroborate and potassium hydroxide raw materials in a polytetrafluoroethylene reaction liner, add ultrapure deionized water and stir evenly, then seal in a reaction vessel.

[0031] (2) Place the reactor in the furnace, heat it and react at a constant temperature. After the set reaction time, gradually cool it down. After the reaction is completed, turn off the furnace and let it cool naturally to room temperature.

[0032] (3) Remove the naturally cooled liner from the reactor, wash the solid mixture in the liner repeatedly with boiling water and dry it to finally obtain the second-order nonlinear optical material zinc fluoroborate salt.

[0033] In step (1), the molar ratio of boric acid, zinc fluoride, potassium carbonate, potassium fluoroborate and potassium hydroxide is 4:1:1:1:5.

[0034] In step (2), the temperature is first raised from room temperature to 220℃ at a rate of 10℃ / min over 120 minutes, and then maintained at a constant temperature of 220±1℃ for 12-48 hours for hydrothermal reaction. The gradient cooling is performed by decreasing the temperature from 220℃ to 70℃ at a gradient cooling rate of 1.8℃ / h after 12-48 hours of constant temperature reaction to terminate the reaction.

[0035] At least one embodiment of the present invention discloses the application of zinc fluoroborate salt, a second-order nonlinear optical material, in second-order nonlinear optical materials.

[0036] The present application will be described in further detail below with reference to experiments and accompanying drawings. It should be noted that the specific embodiments described below are only for further illustration of the present application and should not be construed as limiting the scope of protection of the present application. Those skilled in the art can make some non-essential improvements and adjustments to the present application based on the above application content.

[0037] 1. Explanation

[0038] Unless otherwise specified, all methods used in this invention are conventional methods known to those skilled in the art, and all reagents and materials used are commercially available products, and all instruments used are conventional instruments known to those skilled in the art.

[0039] 2 methods

[0040] 2.1 Preparation of Zinc Fluoroborate Salt

[0041] Boric acid, zinc fluoride, potassium carbonate, potassium fluoroborate, and potassium hydroxide were weighed sequentially in a molar ratio of 4:1:1:1:5 and placed in a polytetrafluoroethylene (PTFE) liner. 0.1 ml of deionized water was added, and the mixture was sealed in a high-pressure reactor. The reactor was then transferred to a hydrothermal temperature-controlled furnace, where the temperature was raised from room temperature to a crystallization temperature of 220±1℃ over 120 minutes at a constant heating rate of 10℃ / min. This temperature was maintained for 48 hours for crystal growth. Subsequently, the reactor was cooled to 70℃ using a gradient cooling rate of 1.8℃ / h to terminate the reaction. The reactor was allowed to cool naturally. The crystalline product obtained from the liner was ultrasonically cleaned with boiling water at 90-100℃ to remove excess powder impurities. After drying in a drying oven, polycrystalline potassium zinc fluoroborate powder was obtained, with a yield of 90% based on the Zn content of the reactants.

[0042] 2.2 Characteristics of Zinc Fluoroborate Salt

[0043] The zinc fluoroborate salt obtained in the above experiment has the chemical formula KZnBO3FH. This zinc fluoroborate salt is a colorless, transparent, triangular prism-shaped bulk crystal, belonging to the hexagonal crystal system, space group P-6c2, and unit cell parameter [missing information]. α=90°, β=90°, γ=120°; Z = 2. For example... Figure 1 The diagram shows the crystal structure of this zinc fluoroborate salt. The basic structural unit of this zinc fluoroborate salt crystal consists of isolated BO3 planar triangular anionic coordinating groups and ZnO3F2 hexahedrons. Each BO3 planar triangle connects to three ZnO3F2 hexahedrons, and each ZnO3F2 hexahedron connects to three BO3 planar triangles. The ZnO3F2 hexahedrons are connected by sharing F atom vertices, forming a one-dimensional chain structure [ZnO3F2] extending along the a-axis or b-axis of the unit cell. ∞ The one-dimensional chain is further bridged by shared oxygen atoms through BO3 groups to form a three-dimensional open framework structure, and potassium ions fill the channels to balance the charge.

[0044] 2.3 Characterization of zinc fluoroborate salt

[0045] Figure 2The image shows a SEM image of zinc fluoroborate. As can be seen from the SEM image, the zinc fluoroborate prepared by the above method is a colorless and transparent triangular prism block. Figure 3 The XRD pattern of this material is shown below. As can be seen from the XRD pattern, the spectrum of this material is similar to that of single-crystal potassium zinc fluoroborate. Figure 1 The crystal planes are aligned and the purity is high, indicating that the material synthesized using the above method is indeed potassium zinc fluoroborate. Figure 4 The above is the electron energy spectrum of potassium zinc fluoroborate. The spectrum shows that the content ratio of its constituent elements matches the chemical formula of potassium fluoroborate, further proving that the material is potassium zinc fluoroborate.

[0046] 2.4 Ultraviolet diffuse reflectance (bandgap) diagram of zinc fluoroborate salt and frequency doubling and phase matching diagram of second-order nonlinear optical effects

[0047] Figure 5 The above-mentioned zinc fluoroborate salt has a UV diffuse reflectance bandgap, which shows that its bandgap is approximately 3.27 eV. Figure 6 The diagram shows the frequency doubling and phase matching of the second-order nonlinear optical effect. As can be seen from the diagram, the material has excellent second-order nonlinear optical effect, with its second harmonic generation (SHG) intensity reaching 7 times that of KH2PO4 (KDP), and it also satisfies phase matching.

[0048] 2.5 Application of Zinc Fluoroborate Salt in Second-Order Nonlinear Optical Materials

[0049] This invention obtains a novel zinc fluoroborate salt with a non-central space group through hydrothermal synthesis. This zinc fluoroborate salt has excellent second-order nonlinear optical properties and its second harmonic generation (SHG) intensity is 7 times that of KH2PO4 (KDP).

[0050] The zinc fluoroborate salt prepared by this invention is a potential second-order nonlinear optical material that can be used in laser frequency conversion, optical communication, integrated circuits, sensors, biomedicine and other fields.

[0051] The embodiments described above are merely examples 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 present invention. 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 modifications and improvements all fall within the scope of protection of the present invention.

Claims

1. A second-order nonlinear optical material, zinc fluoroborate salt, characterized in that, The second-order nonlinear optical material, zinc fluoroborate salt, is potassium zinc fluoroborate with the chemical formula KZnFBO3H. It belongs to the hexagonal crystal system, has a triangular prism-shaped crystal, a space group of P-6c2, and a unit cell parameter of [missing value]. α=90°, β=90°, γ=120°; Z = 2.

2. The second-order nonlinear optical material zinc fluoroborate salt according to claim 1, characterized in that, The basic structural unit of the aluminum phosphate salt consists of isolated BO3 planar triangular anionic coordinating groups and ZnO3F2 hexahedrons; each BO3 planar triangle connects to three ZnO3F2 hexahedrons, and each ZnO3F2 hexahedron connects to three BO3 planar triangles. The ZnO3F2 hexahedrons are connected by sharing F atom vertices to form a one-dimensional chain structure [ZnO3F2] extending along the a-axis or b-axis of the unit cell. ∞ The one-dimensional chain is further bridged by shared oxygen atoms through BO3 groups to form a three-dimensional open framework structure, and potassium ions fill the channels.

3. A method for preparing zinc fluoroborate salt, a second-order nonlinear optical material as described in any one of claims 1-2, characterized in that, Includes the following steps: (1) Place boric acid, zinc fluoride, potassium carbonate, potassium fluoroborate and potassium hydroxide raw materials in a polytetrafluoroethylene reaction liner, add ultrapure deionized water and stir evenly, then seal in a reaction vessel. (2) Place the reactor in the furnace, heat it and react at a constant temperature. After the set reaction time, gradually cool it down. After the reaction is completed, turn off the furnace and let it cool naturally to room temperature. (3) Remove the naturally cooled liner from the reactor, wash the solid mixture in the liner repeatedly with boiling water and dry it to finally obtain the second-order nonlinear optical material zinc fluoroborate salt.

4. The method for preparing the second-order nonlinear optical material zinc fluoroborate salt according to claim 3, characterized in that, In step (1), the molar ratio of boric acid, zinc fluoride, potassium carbonate, potassium fluoroborate and potassium hydroxide is 4:1:1:1:

5.

5. The method for preparing the second-order nonlinear optical material zinc fluoroborate salt according to claim 3, characterized in that, In step (2), the temperature is first raised from room temperature to 220℃ at a rate of 10℃ / min over 120 minutes, and then maintained at a constant temperature of 220±1℃ for 12h-48h for hydrothermal reaction.

6. The method for preparing the second-order nonlinear optical material zinc fluoroborate salt according to claim 5, characterized in that, In step (2), the gradient cooling is to stop the reaction by reducing the temperature from 220℃ to 70℃ at a gradient cooling rate of 1.8℃ / h after a constant temperature reaction of 12h-48h.

7. The application of zinc fluoroborate salt, a second-order nonlinear optical material as described in any one of claims 1-2, in second-order nonlinear optical materials.

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