A fluorinated cerium-based sulfate second-order nonlinear optical crystal material and its preparation and application

Abstract

The invention relates to a fluorinated cerium-based sulfate second-order nonlinear optical crystal material and preparation and application thereof. The chemical formula of the crystal material is Ce3F4(SO4)4, the molecular weight is 880.60, it belongs to the monoclinic system, the space group is C2, the unit cell parameters are #imgabs0#α=90°, β=96.67°~96.87°, γ=90°, Z=2, and the unit cell volume is #imgabs1#. The powder SHG coefficient of the crystal Ce3F4(SO4)4 of the invention is 1.0 times that of KH2PO4(KDP) under 1064nm laser irradiation, and phase matching can be achieved under 1064nm laser irradiation, indicating that the crystal material has broad application prospects in the fields of laser frequency conversion, photoelectric modulation, laser signal holographic storage, etc.

Description

Technical Field

[0001] The invention belongs to the technical field of nonlinear optical crystal materials, and relates to a fluorinated cerium-based sulfate second-order nonlinear optical crystal material and a preparation method and application thereof. Background Art

[0002] The typical feature of second-order nonlinear optical crystals is the frequency doubling effect (SHG). They are an important optoelectronic functional material with important application prospects in the fields of laser frequency conversion, optoelectronic modulation, and holographic storage of laser signals. Currently, commercialized nonlinear optical materials include BBO (β-barium borate), LBO (lithium borate), KDP (potassium dihydrogen phosphate), and KTP (potassium titanyl phosphate). With the development of laser technology and the emergence of tunable lasers, nonlinear optical devices have developed rapidly, including laser frequency doubling, frequency mixing, parametric oscillation and amplification; electro-optical modulation, deflection, Q switching, and photorefractive devices. The above research and applications have put forward more and higher requirements for the physical and chemical properties of nonlinear optical materials, but the current development of nonlinear optical materials is still difficult to meet these requirements. Therefore, it is necessary to continuously develop new types of nonlinear optical crystals. Summary of the invention

[0003] The purpose of the present invention is to provide a fluorinated cerium-based sulfate second-order nonlinear optical crystal material and its preparation and application. The prepared crystal exhibits a strong frequency doubling effect, its powder SHG effect is more than 1 times that of KDP, and phase matching can be achieved. It is a nonlinear optical material with potential application value.

[0004] The purpose of the present invention can be achieved by the following technical solutions:

[0005] One of the technical solutions of the present invention provides a fluorinated cerium-based sulfate second-order nonlinear optical crystal material, whose chemical formula is Ce3F4(SO4)4, belongs to the monoclinic system, its space group is C2, and the unit cell parameters are α=90°,β=96.67°~96.87°,γ=90°,Z=2,the unit cell volume is

[0006] The crystal structure of the fluorosulfate of the present invention is as follows: two crystallographically independent Ce 4+ The ions are coordinated with five oxygen atoms, three fluorine atoms, and six oxygen atoms, two fluorine atoms to form two polyhedrons [Ce(1)O5F3] and [Ce(2)O6F2], in which adjacent Ce(1) and Ce(2) atoms are connected by F(2) atoms, and adjacent Ce(1) and Ce(1) atoms are bridged by F(1), thus forming a two-dimensional [Ce3F4] ∞The two crystallographically independent [SO4] groups cover the adjacent [Ce(1)O5F3] and [Ce(2)O6F2] polyhedra to form three-membered rings and further act as interlayer connectors to form the final three-dimensional structure.

[0007] The second technical solution of the present invention provides a method for preparing a fluorinated cerium-based sulfate second-order nonlinear optical crystal material, wherein a cerium source, a sulfur source, a fluorine source, and water are mixed to form an initial mixed raw material, which is then crystallized under hydrothermal conditions to obtain a target product.

[0008] Furthermore, the cerium source is cerium dioxide or cerium sulfate.

[0009] Furthermore, the sulfur source is sulfuric acid.

[0010] Furthermore, the fluorine source is strontium fluoride.

[0011] Furthermore, the added amounts of the cerium source, sulfur source, fluorine source and water satisfy: the molar ratio of cerium, sulfur, fluorine and water in the initial mixed raw material is 1: (0.5-40): (0.5-50): (1-100). Preferably, the molar ratio of cerium, sulfur, fluorine and water is 1: (0.5-40): (0.5-50): (1-100); more preferably, the molar ratio of cerium, sulfur, fluorine and water is 1: (1-10): (2-20): (5-30).

[0012] Further, the temperature of the hydrothermal condition is 150-230°C, and the time is not less than 24 hours. Preferably, the temperature of the hydrothermal condition is 180-230°C, and the crystallization time is not less than 48 hours.

[0013] Furthermore, after the crystallization is completed, a cooling treatment is performed, and the cooling rate is 0.5 to 15° C. / h. Preferably, the cooling rate is 0.5 to 6° C. / h.

[0014] The third technical solution of the present invention provides the application of fluorinated cerium-based sulfate second-order nonlinear optical crystal material, which is used for visible infrared laser frequency conversion output. Specifically, it can be applied to laser frequency converters, such as for visible light and infrared laser beams to output doubled frequency harmonics. The fluorinated cerium-based sulfate crystal material of the present invention has a large frequency doubling effect. Under 1064nm laser irradiation, its powder frequency doubling effect is about 1.0 times that of KDP crystal, and phase matching can be achieved. In addition, the band gap of the crystal material is 2.50eV, and the thermal stability temperature is 260oC. Therefore, the crystal material has broad application prospects in the field of nonlinear optics.

[0015] Furthermore, the crystal material is used in frequency doubling generators, optical parametric oscillators, optical parametric amplifiers and photoelectric rectifiers.

[0016] Compared with the prior art, the present invention has the following advantages:

[0017] (1) The crystal material of the present invention has a large frequency doubling effect, which is about 1.0 times the frequency doubling intensity of KDP crystal under 1064nm laser irradiation, and can achieve phase matching. In addition, the crystal material has a wide transmission range in the ultraviolet-visible light region and infrared light region, a band gap of 2.50eV, and a thermal stability temperature of 260oC. It has broad application prospects in the fields of laser frequency conversion, photoelectric modulation, laser signal holographic storage, etc.;

[0018] (2) The present invention adopts a hydrothermal method with mild reaction conditions. At a temperature of 150 to 230°C, a high-purity crystalline sample can be obtained in high yield through hydrothermal crystallization. The method is simple and the conditions are mild, which is conducive to large-scale industrial production.

[0019] (3) The fluorinated cerium-based sulfate crystal material of the present invention can be applied to laser frequency converters, and can be used to output visible and infrared laser beams as doubled frequency harmonics. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 It is a schematic diagram of the crystal structure of fluorocerium sulfate;

[0021] Figure 2 The following are comparisons of X-ray diffraction patterns; (a) is the simulated X-ray diffraction pattern of sample 1# based on the crystal structure analyzed from single crystal X-ray diffraction data; (b) is the pattern obtained by X-ray diffraction test after sample 1# is ground into powder;

[0022] Figure 3 is the UV-Vis-NIR absorption spectrum of sample 1#;

[0023] Figure 4 It is the infrared spectrum (2.5-25 μm) spectrum of sample 1#;

[0024] Figure 5 This is the thermogravimetric analysis spectrum of sample 1#;

[0025] Figure 6 It is the second harmonic signal diagram of sample 1# and KDP sample with size ranging from 105 to 150 μm;

[0026] Figure 7 This is the second harmonic phase matching diagram of sample 1# in the 1.064μm band. DETAILED DESCRIPTION

[0027] The present invention is described in detail below in conjunction with the accompanying drawings and specific embodiments. This embodiment is implemented based on the technical solution of the present invention, and provides a detailed implementation method and specific operation process, but the protection scope of the present invention is not limited to the following embodiments.

[0028] In the following examples, unless otherwise specified, raw materials or processing techniques are conventional commercially available raw materials or conventional processing techniques in the art.

[0029] The cerium source, sulfur source, fluorine source and water are mixed in a certain proportion to form a starting raw material, and the mixture is sealed in a hydrothermal reactor with a polytetrafluoroethylene liner, and the temperature is raised to the crystallization temperature. After a period of constant temperature, the temperature of the reaction system is slowly lowered to room temperature at a certain rate, and the mixture is filtered and washed to obtain transparent block-shaped fluorinated cerium sulfate crystals.

[0030] The relationship between the type and ratio of raw materials in the initial mixture, crystallization temperature, crystallization time and sample number is shown in Table 1.

[0031] Table 1 Correspondence between samples, raw materials and synthesis conditions

[0032]

[0033] Embodiment 2:

[0034] Crystal structure analysis

[0035] The structures of samples 1# to 6# were analyzed using single crystal X-ray diffraction and powder X-ray diffraction methods.

[0036] The single crystal X-ray diffraction test was carried out on a D8 VENTURE CMOS X-ray single crystal diffractometer from Bruker, Germany. The crystal size is 0.12×0.07×0.06mm 3 ; The data collection temperature is 293K, and the diffraction light source is graphite monochromatized Mo-Kα rays The scanning mode was ω; the data were processed for absorption correction using the Multi-Scan method. The structure analysis was completed using the SHELXTL-97 program package; the positions of heavy atoms were determined using the direct method, and the coordinates of the remaining atoms were obtained using the difference Fourier synthesis method; the F-based 2 The full-matrix least-squares method was used to refine the coordinates of all atoms and the anisotropic thermal parameters.

[0037] The powder X-ray diffraction test was carried out on a Bruker D8 X-ray powder diffractometer from Bruker, Germany. The test conditions were a fixed target monochromatic light source Cu-Kα, a wavelength The voltage and current are 40kV / 20A, the slits DivSlit / RecSlit / SctSlit are 2.00deg / 0.3mm / 2.00deg respectively, the scanning range is 5-70°, and the scanning step is 0.02°. Ce3F4(SO4)4, with a molecular weight of 880.60, belongs to the monoclinic system, its space group is C2, and the unit cell parameters are α=90°,β=96.67°~96.87°,γ=90°,Z=2,the unit cell volume is

[0038] Among them, the single crystal X-ray diffraction test results show that samples 1#~6# have the same chemical formula and crystal structure, the chemical formula is Ce3F4(SO4)4, the molecular weight is 880.60, it belongs to the monoclinic system, its space group is C2, and the unit cell parameters are α=90°,β=96.67°~96.87°,γ=90°,Z=2,the unit cell volume is

[0039] Take sample 1# as a typical example, its crystal structure data is α=90°,β=96.773°,γ=90°,Z=2,the unit cell volume is Its crystal structure is Figure 1 shown.

[0040] The powder X-ray diffraction test results show that in the powder XRD spectra of samples 1# to 6#, the peak positions of each sample are basically the same, but the peak intensities are slightly different.

[0041] Take sample 1# as a typical example. Figure 2 shown. Figure 2 The spectrum obtained by X-ray diffraction test after sample 1# in (a) was ground into powder is similar to Figure 2 In (b), based on the crystal structure analyzed by single crystal X-ray diffraction, the simulated X-ray diffraction pattern has consistent peak positions and peak intensities, indicating that the obtained sample has high purity.

[0042] Embodiment 3:

[0043] UV diffuse reflectance spectrum test

[0044] The diffuse reflectance absorption spectrum test of sample 1# was conducted on a Cary 5000 UV-visible-near infrared spectrophotometer from Agilent Technologies, USA. Figure 3 As shown by Figure 3 It can be seen that the compound has a wide optical transmittance range and an optical band gap of 2.50 eV.

[0045] Embodiment 4:

[0046] Infrared spectrum test

[0047] The infrared spectrum test of sample 1# was conducted on a Nicolet iS10 Fourier infrared spectrometer from Thermo Fisher Scientific Inc., USA. The results are as follows Figure 4 As shown by Figure 4 It can be seen that the compound has a wide optical transmittance range.

[0048] Embodiment 5:

[0049] Thermogravimetric testing

[0050] The thermogravimetric test of sample 1# was conducted on a Netzsch STA 409PC thermogravimetric analyzer manufactured by Netzsch Equipment Manufacturing Co., Ltd., Germany. The results are shown in the figure below. Figure 5 As shown by Figure 5 It can be seen that the compound can be stable to 260oC and has good thermal stability.

[0051] Embodiment 6:

[0052] Frequency doubling test experiment and results

[0053] The frequency doubling test experiment of sample 1# is as follows: a laser with a wavelength of 1064nm generated by a Q-switched Nd:YAG solid laser is used as the fundamental frequency light to irradiate the tested crystal powder, a photomultiplier tube is used to detect the generated second harmonic, and an oscilloscope is used to display the harmonic intensity. The crystal sample and the control sample KDP crystal are ground separately, and crystals of different particle sizes are sieved out with a standard sieve. The particle size ranges are less than 26, 26-50, 50-74, 74-105, 105-150, 150-200, and 200-280μm. Observe the trend of the frequency doubling signal intensity changing with the particle size to determine whether phase matching can be achieved. Under the same test conditions, the second harmonic intensity generated by the sample and the KDP sample is compared to obtain the relative size of the sample frequency doubling effect.

[0054] The test results show that the compound fluorinated cerium sulfate crystal has a large frequency doubling effect. Under 1064nm wavelength laser irradiation, the frequency doubling signal intensity is 1.0 times that of the control sample KDP crystal (such as Figure 6 ), phase matching can be achieved (such as Figure 7 ).

[0055] The above description of the embodiments is to facilitate the understanding and use of the invention by those skilled in the art. It is obvious that those skilled in the art can easily make various modifications to these embodiments and apply the general principles described herein to other embodiments without creative work. Therefore, the present invention is not limited to the above embodiments, and improvements and modifications made by those skilled in the art based on the disclosure of the present invention without departing from the scope of the present invention should be within the scope of protection of the present invention.

Claims

1. A fluorinated cerium-based sulfate second-order nonlinear optical crystal material, characterized in that: Its chemical formula is Ce3F4(SO4)4, it belongs to the monoclinic system, its space group is C2, and its unit cell parameters are α=90°,β=96.67°~96.87°,γ=90°,Z=2,the unit cell volume is 2. The method for preparing a fluorinated cerium-based sulfate second-order nonlinear optical crystal material according to claim 1, characterized in that: A cerium source, a sulfur source, a fluorine source, and water are mixed to form an initial mixed raw material, which is then crystallized under hydrothermal conditions to obtain a target product.

3. The method for preparing a fluorinated cerium-based sulfate second-order nonlinear optical crystal material according to claim 2, characterized in that: The cerium source is cerium dioxide or cerium sulfate.

4. The method for preparing a fluorinated cerium-based sulfate second-order nonlinear optical crystal material according to claim 2, characterized in that: The sulfur source is sulfuric acid.

5. The method for preparing a fluorinated cerium-based sulfate second-order nonlinear optical crystal material according to claim 2, characterized in that: The fluorine source is strontium fluoride.

6. The method for preparing a fluorinated cerium-based sulfate second-order nonlinear optical crystal material according to claim 2, characterized in that: The added amounts of the cerium source, sulfur source, fluorine source and water satisfy the following requirement: the molar ratio of cerium element, sulfur element, fluorine element and water in the initial mixed raw material is 1:(0.5-40):(0.5-50):(1-100).

7. The method for preparing a fluorinated cerium-based sulfate second-order nonlinear optical crystal material according to claim 2, characterized in that: The temperature of the hydrothermal condition is 150-230°C and the time is not less than 24 hours.

8. The method for preparing a fluorinated cerium-based sulfate second-order nonlinear optical crystal material according to claim 2, characterized in that: After the crystallization is completed, a cooling treatment is performed, and the cooling rate is 0.5 to 15°C / h.

9. The use of the fluorinated cerium-based sulfate second-order nonlinear optical crystal material according to claim 1, characterized in that: The crystal material is used for visible infrared laser frequency conversion output.

10. The use of the fluorinated cerium-based sulfate second-order nonlinear optical crystal material according to claim 9, characterized in that: The crystal material is used in frequency doubling generators, optical parametric oscillators, optical parametric amplifiers and photoelectric rectifiers.

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