CN113897679B - Zirconium fluorosulfate second-order nonlinear optical crystal material and preparation method and application thereof - Google Patents

Abstract

The invention relates to a zirconium fluorosulfate second-order nonlinear optical crystal material and a preparation method and application thereof, wherein the chemical formula of the crystal material is ZrF ₂ (SO ₄ ) Belongs to the orthorhombic system, and the space group is Pca2 ₁ With cell parameters of

α = β = γ =90 °, Z =4, unit cell volume

Compared with the prior art, the crystal ZrF of the invention ₂ (SO ₄ ) Under 1064nm laser irradiation, the powder SHG coefficient is KH ₂ PO ₄ 5.2 times of (KDP) and can realize phase matching under 1064nm laser irradiation.

Description

Zirconium fluorosulfate second-order nonlinear optical crystal material, preparation method and application thereof

technical field

The invention belongs to the fields of inorganic chemistry, crystallography and nonlinear optical materials, relates to an inorganic transition metal fluorosulfate nonlinear optical crystal, and in particular relates to a zirconium fluorosulfate second-order nonlinear optical crystal material and a preparation method thereof. application.

Background technique

Nonlinear optics (NLO) crystalline materials with second harmonic (SHG) properties have important applications in precision manufacturing such as laser frequency conversion, micromachining, optoelectronic modulation, lithography, and semiconductor inspection, as it can produce continuously tunable coherence Light. An ideal NLO crystal should satisfy the following criteria: strong second harmonic (SHG) response, large band gap, easy growth of large-sized single crystals, and good physicochemical stability. However, these factors constrain each other, especially between the SHG response and the band gap. For example, the NLO crystal KTiOPO ₄ (KTP) exhibits a strong SHG response, while the narrow band gap of this material hinders its practical application in the ultraviolet region. Therefore, developing an effective NLO material with a good balance between the frequency doubling effect and the optical band gap is an important research direction in contemporary times.

In recent years, metal sulfates are a class of nonlinear optical crystal materials that are promising for practical applications. Since sulfate is an isotropic tetrahedral unit with nearly non-polar T _d symmetry, this type of material suffers from a weak SHG signal.

SUMMARY OF THE INVENTION

The purpose of the present invention is to solve the problem that the SHG signal of the current tetrahedral element ([SO ₄ ] ^2- ) crystal material is weak, and to provide a UV nonlinear optical crystal that achieves a balance between the frequency doubling intensity and the optical band gap and has good performance. Material - zirconium fluorosulfate second-order nonlinear optical crystal material and preparation method and application thereof.

In order to enhance the nonlinear optical response, the present invention ^{obtains a crystal material with both wide band gap and strong nonlinear optical properties by introducing do transition metal ion Zr 4+ into} the metal sulfate system.

The object of the present invention can be realized through the following technical solutions:

A first aspect of the present invention provides a zirconium fluorosulfate second-order nonlinear optical crystal material, and the chemical formula of the crystal material is ZrF ₂ (SO ₄ ).

The molecular weight of this crystalline material was 225.29.

α＝β＝γ＝90°，Z＝4，晶胞体积为

Preferably, the crystal material belongs to the orthorhombic crystal system, its space group is Pca2 ₁ , and the unit cell parameter is

α=β=γ=90°, Z=4, the unit cell volume is

Preferably, the crystal structure of the crystalline material is: each Zr ⁴⁺ ion is coordinated with four oxygen atoms and four fluorine atoms to form a [ZrO ₄ F ₄ ] polyhedral unit, wherein the four oxygen atoms are respectively coordinated with different four [SO ₄ ] groups are connected; adjacent [ZrO ₄ F ₄ ] polyhedral units are connected to each other in a co-pointed [F(1) and F(2)] manner, thus forming [ZrO ₄ F ₄ ] _∞ layers The asymmetric [SO ₄ ] group is located between the [ZrO ₄ F ₄ ] _∞ layers, acting as an interlayer linker connecting four Zr atoms, forming a three-dimensional structure.

The second aspect of the present invention provides the preparation method of the zirconium fluorosulfate second-order nonlinear optical crystal material, comprising the following steps:

(1) mixing zirconium source, sulfur source, fluorine source and water to form a mixed raw material;

(2) Crystallizing the mixed raw material under hydrothermal conditions to obtain the zirconium fluorosulfate second-order nonlinear optical crystal material.

Preferably, the zirconium source is zirconium dioxide or zirconium fluoride, more preferably, the zirconium source is zirconium fluoride; the sulfur source is sulfuric acid; the fluorine source is hydrofluoric acid or zirconium fluoride, more preferably The fluorine source is zirconium fluoride.

Preferably, the molar ratio of zirconium element, sulfur element, fluorine element and water in the mixed raw material is 1:(0.5-50):(0.5-50):(1-50).

Further preferably, the molar ratio of zirconium element, sulfur element, fluorine element and water in the mixed raw material is 1:(2-10):(1-10):(2-20).

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

Preferably, the preparation method further includes the step of cooling to room temperature after crystallization, and the cooling rate is 0.5-15° C./h. More preferably, the cooling rate is 0.5 to 6°C/h.

The zirconium fluorosulfate crystal material of the present invention has a large frequency doubling effect, and its powder frequency doubling effect is about 5.2 times that of KH ₂ PO ₄ crystal under the irradiation of 1064 nm laser, and can achieve phase matching. In addition, the crystalline material has a band gap of 6.02 eV and a thermally stable temperature of 200 °C. Therefore, the crystal material has broad application prospects in the field of nonlinear optics. For example, it can be used in laser frequency converters. The laser frequency converter is used for outputting visible light laser beams with double frequency harmonics.

The third aspect of the present invention provides the application of the second-order nonlinear optical crystal material of zirconium fluorosulfate, and the crystal material is used for frequency conversion output of ultraviolet laser.

Preferably, the crystal material is used in frequency doubling generators, optical parametric oscillators, optical parametric amplifiers and photoelectric rectifiers.

Compared with the prior art, the beneficial effects of the present invention include but are not limited to the following aspects:

(1) The present invention provides a new inorganic crystal material zirconium fluorosulfate, which can easily form a polarizable fluorozirconium-oxygen polyhedron by replacing oxygen ions with more negatively charged fluoride ions in the transition metal center polyhedron The crystal material has a large frequency doubling effect, which is about 5.2 times the frequency doubling intensity of KH ₂ PO ₄ crystal under 1064 nm laser irradiation, and can achieve phase matching. In addition, the crystal material has a wide transmission range in the ultraviolet and visible regions, a band gap of 6.02 eV, and a thermally stable temperature of 200 °C. It has broad application prospects in the fields of laser frequency conversion, photoelectric modulation, and laser signal holographic storage. ;

(2) The present invention provides a method for preparing the zirconium fluorosulfate crystal material. By adopting a hydrothermal method with mild reaction conditions, through hydrothermal crystallization at a temperature of 150-230° C., high-purity can be obtained in high yield. For crystalline samples, the method is simple and the conditions are mild, which is conducive to the realization of large-scale industrial production;

(3) The zirconium fluorosulfate crystal material of the present invention can be applied to a laser frequency converter, and can be used to output ultraviolet and visible laser beams with double frequency harmonics.

Description of drawings

Fig. 1 is the crystal structure schematic diagram of zirconium fluorosulfate of the present invention;

Figure 2 is a comparison of X-ray diffraction patterns; (a) is the crystal structure of sample 1# analyzed according to single crystal X-ray diffraction data, and the X-ray diffraction pattern obtained by simulation; (b) is sample 1# is ground into powder and used The spectrum obtained by X-ray diffraction test;

Fig. 3 is the ultraviolet-visible-near-infrared transmission spectrum of sample 1#;

Fig. 4 is the infrared spectrum (2.5～25μm) spectrum of sample 1#;

Fig. 5 is the thermogravimetric analysis spectrum of sample 1#;

Figure 6 is the second harmonic signal diagram of sample 1# and KH ₂ PO ₄ sample size in the range of 105-150 μm;

Figure 7 is the second harmonic phase matching diagram of sample 1# in the 1.064μm band.

Detailed ways

A zirconium fluorosulfate second-order nonlinear optical crystal material, the chemical formula of the crystal material is ZrF ₂ (SO ₄ ), and the molecular weight is 225.29.

α＝β＝γ＝90°，Z＝4，晶胞体积为

优选该晶体材料的晶体结构为：每个Zr⁴⁺离子分别和四个氧原子以及四个氟原子配位形成[ZrO₄F₄]多面体单元，其中四个氧原子分别和不同的四个[SO₄]基团连接；相邻的[ZrO₄F₄]多面体单元以共点的[F(1)和F(2)]方式相互连接，从而形成了[ZrO₄F₄]_∞层状结构；不对称的[SO₄]基团位于[ZrO₄F₄]_∞层之间，作为连接四个Zr原子的层间连接体，形成三维结构。Preferably, the crystal material belongs to the orthorhombic crystal system, its space group is Pca2 ₁ , and the unit cell parameter is

α=β=γ=90°, Z=4, the unit cell volume is

Preferably, the crystal structure of the crystalline material is: each Zr ⁴⁺ ion is coordinated with four oxygen atoms and four fluorine atoms to form a [ZrO ₄ F ₄ ] polyhedral unit, wherein the four oxygen atoms are respectively coordinated with four different [ZrO 4 F 4 ] polyhedral units. SO ₄ ] groups are connected; adjacent [ZrO ₄ F ₄ ] polyhedral units are connected to each other in a co-pointed [F(1) and F(2)] manner, thus forming a [ZrO ₄ F ₄ ] _∞ layered structure ; Asymmetric [SO ₄ ] groups are located between the [ZrO ₄ F ₄ ] _∞ layers, acting as interlayer connectors connecting four Zr atoms, forming a three-dimensional structure.

The preparation method of the zirconium fluorosulfate second-order nonlinear optical crystal material comprises the following steps:

(1) mixing zirconium source, sulfur source, fluorine source and water to form a mixed raw material;

(2) Crystallizing the mixed raw material under hydrothermal conditions to obtain the zirconium fluorosulfate second-order nonlinear optical crystal material.

Preferably, the zirconium source is zirconium dioxide or zirconium fluoride, more preferably the zirconium source is zirconium fluoride; preferably the sulfur source is sulfuric acid; the fluorine source is preferably hydrofluoric acid or zirconium fluoride, and more preferably the fluorine source is zirconium fluoride. Preferably, the molar ratio of zirconium element, sulfur element, fluorine element and water in the mixed raw material is 1:(0.5-50):(0.5-50):(1-50). More preferably, the molar ratio of zirconium element, sulfur element, fluorine element and water in the mixed raw material is 1:(2-10):(1-10):(2-20). Preferably, the temperature of the hydrothermal conditions is 150-230° C., and the crystallization time is not less than 24 hours. Further preferably, the temperature of the hydrothermal condition is 180-230°C, and the crystallization time is not less than 48h. Preferably, the preparation method further includes the step of cooling to room temperature after crystallization, and the cooling rate is 0.5-15°C/h. More preferably, the cooling rate is 0.5 to 6°C/h.

The zirconium fluorosulfate crystal material of the present invention has a large frequency doubling effect, and its powder frequency doubling effect is about 5.2 times that of KH ₂ PO ₄ crystal under the irradiation of 1064 nm laser, and can achieve phase matching. In addition, the crystalline material has a band gap of 6.02 eV and a thermally stable temperature of 200 °C. Therefore, the crystal material has broad application prospects in the field of nonlinear optics. For example, it can be used in laser frequency converters. The laser frequency converter is used for outputting visible light laser beams with double frequency harmonics.

The zirconium fluorosulfate second-order nonlinear optical crystal material can be applied to ultraviolet laser frequency conversion output. Preferably, the crystal material can be used in frequency doubling generators, optical parametric oscillators, optical parametric amplifiers and photoelectric rectifiers.

The embodiments of the present invention are described in detail below. This embodiment is implemented on the premise of the technical solution of the present invention, and provides a detailed implementation manner and a specific operation process, but the protection scope of the present invention is not limited to the following implementation. example.

Hydrothermal synthesis of the sample of Example 1

The zirconium source, sulfur source, fluorine source and water are mixed into starting materials according to a certain proportion, sealed in a hydrothermal reactor with a polytetrafluoroethylene lining, heated to the crystallization temperature, and kept at a constant temperature for a period of time, with 3 The temperature of the reaction system is slowly lowered to room temperature at a rate of ℃/h, and the transparent bulk zirconium fluorosulfate crystals can be obtained by filtration and cleaning.

The relationship between the types and proportions of raw materials in the initial mixture, the crystallization temperature, the crystallization time and the sample number is shown in Table 1.

Table 1 Correspondence between samples and raw materials and synthesis conditions

Example 2 Crystal Structure Analysis

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

扫描方式为ω；数据采用Multi-Scan方法进行吸收校正处理。结构解析采用SHELXTL-97程序包完成；用直接法确定重原子的位置，用差值傅立叶合成法得到其余原子坐标；用基于F²的全矩阵最小二乘法精修所有原子的坐标及各向异性热参数。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 0.23×0.19×0.15mm ³ ; the data collection temperature is 293K, and the diffraction light source is Mo-Kα ray monochromated by graphite

The scanning mode is ω; the data is processed by the Multi-Scan method for absorption correction. Structural analysis was done using the SHELXTL-97 package; the positions of heavy atoms were determined by the direct method, and the coordinates of the remaining atoms were obtained by the difference Fourier synthesis method; the coordinates and anisotropy of all atoms were refined by the full-matrix least squares method based on F ² thermal parameters.

电压电流为40kV/20A，狭缝DivSlit/RecSlit/SctSlit分别为2.00deg/0.3mm/2.00deg，扫描范围5–70°，扫描步长0.02°。ZrF₂(SO₄)，分子量为225.29，属于正交晶系，其空间群为Pca2₁，晶胞参数为

α＝β＝γ＝90°，Z＝4，晶胞体积为

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, wavelength

The voltage and current were 40kV/20A, the slit DivSlit/RecSlit/SctSlit were 2.00deg/0.3mm/2.00deg, respectively, the scanning range was 5–70°, and the scanning step was 0.02°. ZrF ₂ (SO ₄ ), with a molecular weight of 225.29, belongs to the orthorhombic system, its space group is Pca2 ₁ , and the unit cell parameter is

α=β=γ=90°, Z=4, the unit cell volume is

α＝β＝γ＝90°，Z＝4，晶胞体积为

Among them, the single crystal X-ray diffraction test results show that samples 1# to 6# have the same chemical structural formula and crystal structure, the chemical formula is ZrF ₂ (SO ₄ ), the molecular weight is 225.29, belong to the orthorhombic system, and its space group is Pca2 ₁ , the unit cell parameters are

α=β=γ=90°, Z=4, the unit cell volume is

α＝β＝γ＝90°，Z＝4，晶胞体积为

其晶体结构如图1所示。Taking sample 1# as a typical representative, its crystal structure data is

α=β=γ=90°, Z=4, the unit cell volume is

Its crystal structure is shown in Figure 1.

The powder X-ray diffraction test results show that in the XRD patterns of samples 1# to 6#, the peak positions of each sample are basically the same, and the peak intensity is slightly different.

Take sample 1# as a typical representative, as shown in Figure 2. In Fig. 2(a), the sample 1# is ground into powder and obtained by X-ray diffraction test and in Fig. 2(b) according to its single crystal X-ray diffraction analysis of the crystal structure, the simulated X-ray diffraction pattern, the peak The positions and peak intensities are consistent, indicating that the obtained samples are of high purity.

Embodiment 3 Ultraviolet transmission spectrum test

The transmission spectrum test of sample 1# was carried out on a Cary 5000 UV-Vis-NIR spectrophotometer of Agilent, USA. The results are shown in Fig. 3, and it can be seen from Fig. 3 that the compound has no obvious absorption in the range of 206 nm to 2500 nm. The compound has a wide optical transmission range, the UV absorption cut-off edge is 206 nm, and the corresponding optical band gap is 6.02 eV.

Example 4 Infrared Spectrum Test

The infrared spectrum test of sample 1# was carried out on the Nicolet iS10 Fourier infrared spectrometer of Thermo Fisher Scientific Co., Ltd. The results are shown in Fig. 4, and it can be seen from Fig. 4 that the compound has a wide optical transmission range.

Example 5 Thermogravimetric test

The thermogravimetric test of sample 1# was carried out on a Netzsch STA 409PC thermogravimetric analyzer. The results are shown in Figure 5. It can be seen from Figure 5 that the compound can be stable to 200°C and has good thermal stability.

Embodiment 6 Frequency doubling test experiment and results

The frequency doubling test experiment of sample 1# is as follows: The laser with a wavelength of 1064 nm generated by a Q-switched Nd:YAG solid-state laser is used as the fundamental frequency light, and the crystal powder to be tested is irradiated, and the second harmonic generated is detected by a photomultiplier tube. Display the harmonic intensity with an oscilloscope. Grind the KH ₂ PO ₄ crystals of the crystal sample and the control sample respectively, and sieve crystals with different particle sizes with a standard sieve. 150～200, 200～280μm. Observe the trend of the frequency doubling signal intensity changing with the granularity, and judge whether it can achieve phase matching. Under the same test conditions, compare the intensity of the second harmonic generated by the sample and the KH ₂ PO ₄ sample, so as to obtain the relative magnitude of the frequency doubling effect of the sample.

The test results show that the compound zirconium fluorosulfate crystal has a large frequency doubling effect. Under the irradiation of the 1064nm wavelength laser, the frequency doubling signal intensity is 5.2 times that of the control sample KH ₂ PO ₄ crystal (as shown in Figure 6), and the phase can be realized. match (see Figure 7).

The foregoing description of the embodiments is provided to facilitate understanding and use of the invention by those of ordinary skill in the art. It will be apparent to those skilled in the art that various modifications to these embodiments can be readily made, and the generic principles described herein can be applied to other embodiments without inventive step. Therefore, the present invention is not limited to the above-mentioned embodiments, and improvements and modifications made by those skilled in the art according to the disclosure of the present invention without departing from the scope of the present invention should all fall within the protection scope of the present invention.

Claims (6)

1. The application of zirconium fluorosulfate second-order nonlinear optical crystal material is characterized in that the chemical formula of the crystal material is ZrF ₂ (SO ₄ )；

The crystalline material belongs to the orthorhombic system, and the space group isPca2 ₁ Cell parameter ofa = 7.800~8.00 Å，b = 5.97~6.17 Å，c = 7.82~8.02 Å，α = β = γ = 90°，ZUnit cell volume of =4V = 380.07 Å ³ ；

The crystal material is used for ultraviolet laser frequency conversion output;

the crystal material is prepared by the following processes:

(1) Mixing a zirconium source, a sulfur source, a fluorine source and water to form a mixed raw material;

(2) Crystallizing the mixed raw materials under a hydrothermal condition to obtain the zirconium fluorosulfate second-order nonlinear optical crystal material;

the temperature of the hydrothermal condition is 150-230 ℃, and the crystallization time is not less than 24h;

the preparation method also comprises the step of cooling to room temperature after crystallization, wherein the cooling rate is 0.5 to 15 ℃/h.

2. The use of the zirconium fluorosulfate second order nonlinear optical crystal material of claim 1, wherein the crystal structure of the crystal material is: each Zr ⁴⁺ Ions coordinated to four oxygen atoms and four fluorine atoms, respectively, [ ZrO ] ₄ F ₄ ]Polyhedral units in which four oxygen atoms are respectively different from four [ SO ] ₄ ]Group attachment; adjacent [ ZrO ] of ₄ F ₄ ]Polyhedral unit with concurrent [ F (1) and F (2)]Are connected to each other in such a way that [ ZrO ] is formed ₄ F ₄ ] _∞ A layered structure; asymmetric [ SO ₄ ]The radical being located in [ ZrO ₄ F ₄ ] _∞ Between the layers, an interlayer connector connecting four Zr atoms is formed to have a three-dimensional structure.

3. Use of a zirconium fluorosulfate second order nonlinear optical crystal material in accordance with claim 1 wherein the zirconium source is zirconium dioxide or zirconium fluoride; the sulfur source is sulfuric acid; the fluorine source is hydrofluoric acid or zirconium fluoride.

4. The use of the zirconium fluorosulfate second order nonlinear optical crystal material of claim 1, wherein the molar ratio of zirconium, sulfur, fluorine and water in the mixed raw material is 1: (0.5 to 50): (0.5 to 50): (1 to 50).

5. The use of the zirconium fluorosulfate second order nonlinear optical crystal material of claim 4, wherein the molar ratio of zirconium element, sulfur element, fluorine element and water in the mixed raw material is 1: (2 to 10): (1 to 10): (2 to 20).

6. Use of a zirconium fluorosulfate second order nonlinear optical crystal material in accordance with claim 1, characterized in that the crystal material is used in frequency doubling generators, optical parametric oscillators, optical parametric amplifiers and optoelectronic rectifiers.

Images