Be2 (BO3) (HTeO3) compound and crystal, preparation method and application thereof

Abstract

The invention discloses a Be2 (BO3) (HTeO3) compound as well as a crystal, a preparation method and application thereof in nonlinear optics, the crystal realizes connection of [Be2BO3F2] infinity layers through a (HTeO3)-group, that is, the (HTeO3)-group in the structure is connected with two opposite (BeO4) 6-tetrahedrons in the adjacent [Be2BO3O2] infinity layers through shared suspended O atoms, and the (HTeO3)-group in the [Be2BO3O2] infinity layers is disordered in position around the c-axis direction. The crystal has a frequency-doubled effect equivalent to that of KBBF, and has the potential to be applied to an ultraviolet region to a middle and far infrared region; meanwhile, the crystal does not absorb moisture and has good physical properties.

Description

Technical Field

[0001] The invention belongs to the technical field of functional crystal materials, and in particular relates to a Be2(BO3)(HTeO3) compound and its crystal, a preparation method and application in nonlinear optics. Background Art

[0002] Nonlinear optical crystals have become cutting-edge functional materials widely used in the field of optoelectronic technology because of their frequency conversion function, which can easily realize the tunability of all-solid-state laser wavelengths. Such crystals play an important role in laser micromachining, information storage and other fields. Previously, the development of most nonlinear optical crystals mainly came from traditional compound systems such as borates, phosphates and iodates. However, with the continuous advancement of laser technology, higher requirements are placed on the performance of nonlinear optical crystals. It has become increasingly difficult to find new nonlinear optical crystals from traditional single compound systems. Therefore, the development of new synthesis strategies, such as the expansion of new compound systems such as complex salts, is of great significance to promote the research of nonlinear optical crystals. Summary of the invention

[0003] In order to solve the above technical problems, the present invention provides a compound with the chemical formula Be2(BO3)(HTeO3).

[0004] The present invention also provides a method for preparing the compound with the chemical formula Be2(BO3)(HTeO3), which comprises: mixing a Be-containing compound, a B-containing compound and a Te-containing compound, and preparing the compound by a hydrothermal reaction.

[0005] According to an embodiment of the present invention, the Be-containing compound is selected from at least one of BeO, BeSO4·4H2O or BeF2, preferably BeO.

[0006] According to an embodiment of the present invention, the B-containing compound is selected from at least one of H3BO3, B2O3, HBO2 and Li2B4O7, preferably H3BO3.

[0007] According to an embodiment of the present invention, the Te-containing compound is selected from TeO2 or H2TeO3, preferably TeO2.

[0008] According to an embodiment of the present invention, in the Be-containing compound, the B-containing compound and the Te-containing compound, n(Be):n(B):n(Te)=(1-3):(1-6):(1-3); preferably 2:(1-5):(1-2); exemplified by 1:1:1, 1:3:2, 1:6:3, 3:1:1, 2:1:1, 2:5:1, 2:2:1.5.

[0009] According to an embodiment of the present invention, the reaction is carried out in a solvent, and the solvent can be selected from an organic solvent or an inorganic solvent, preferably an inorganic solvent, such as water, exemplified by deionized water.

[0010] According to an embodiment of the present invention, the volume ratio of the sum of the masses of the Be-containing compound, the B-containing compound, and the Te-containing compound to the solvent can be (25-80) g:100 mL, preferably (40-60) g:100 mL; exemplary are 26 g:100 mL, 39 g:100 mL, 52 g:100 mL, and 65 g:100 mL.

[0011] According to an embodiment of the present invention, the reaction temperature of the hydrothermal reaction may be 160 to 240° C., preferably 180 to 220° C., for example 180° C., 200° C., 220° C. Further, the heating rate of the hydrothermal reaction may be 10 to 30° C. / h, exemplified by 10° C. / h, 20° C. / h, 30° C. / h.

[0012] According to an embodiment of the present invention, the reaction time of the hydrothermal reaction may be 1 to 3 days, exemplified by 1 day or 2 days.

[0013] According to an embodiment of the present invention, the preparation method further comprises: after the hydrothermal reaction is completed, collecting a compound with a chemical formula of Be2(BO3)(HTeO3) from the reaction solution.

[0014] The present invention also provides a nonlinear optical crystal, the chemical formula of which is Be2(BO3)(HTeO3), that is, the nonlinear optical crystal is a Be2(BO3)(HTeO3) crystal.

[0015] According to an embodiment of the present invention, the nonlinear optical crystal belongs to the hexagonal system and has the following characteristics: Figure 1 The crystal structure shown has a space group of The unit cell parameters are α=β=90°, γ=120, z=2.

[0016] According to an embodiment of the present invention, the nonlinear optical crystal has the following Figure 2 X-ray diffraction pattern shown.

[0017] According to an embodiment of the present invention, the powder frequency doubling effect of the nonlinear optical nonlinear optical crystal is 1.24 times that of KH2PO4 (KDP).

[0018] According to the embodiment of the present invention, the ultraviolet absorption cut-off wavelength of the nonlinear optical crystal can reach 239 nm, that is, the nonlinear optical crystal is an ultraviolet-mid-infrared and far-infrared frequency doubling optical crystal.

[0019] According to the embodiment of the present invention, the nonlinear optical crystal can achieve a relatively high transmittance between 0.3 and 5.5 μm, and the band gap of the crystal is 4.32 eV.

[0020] According to an embodiment of the present invention, the nonlinear optical crystal is composed of honeycomb [Be2BO3O2] ∞ Layer and [HTeO3] ∞ The layers are stacked alternately.

[0021] The present invention also provides a method for preparing the nonlinear optical crystal, the method comprising:

[0022] The Be-containing compound, the B-containing compound and the Te-containing compound are mixed and heated for crystallization to obtain the crystal.

[0023] Preferably, the selection of the Be-containing compound, the B-containing compound and the Te-containing compound is respectively consistent with the selection in the above-mentioned preparation method of the compound with the chemical formula Be2(BO3)(HTeO3).

[0024] According to an embodiment of the present invention, the method is carried out in a solvent. The solvent has the meaning as described above.

[0025] According to an embodiment of the present invention, the temperature of the heating crystallization is 160-240° C., preferably 180-220° C., and exemplarily 180° C., 200° C., 220° C., and 240° C. For example, the time of the heating crystallization is 3-15 days, preferably 5-7 days, and exemplarily 5 days, 7 days, 10 days, and 15 days.

[0026] According to an embodiment of the present invention, the preparation method further comprises: after the crystallization is completed, cooling, separating and drying the reaction liquid to obtain the crystal.

[0027] For example, the cooling rate is 1 to 10°C / h, exemplified by 1°C / h, 5°C / h, and 10°C / h.

[0028] According to an embodiment of the present invention, the preparation method specifically comprises the following steps:

[0029] (a) mixing a Be-containing compound, a B-containing compound, a Te-containing compound and a solvent, and heating the mixture to 160 to 240° C. at a rate of 10 to 30° C. / h for crystallization;

[0030] (b) After the crystallization is completed, the reaction system is cooled to room temperature at a rate of 1 to 10° C. / h, and the crystals can be obtained after separation and drying.

[0031] The present invention also provides applications of the crystal in the fields of laser frequency doubling, electro-optic modulation, photorefractive information processing and information storage; preferably, the crystal is used in a frequency doubling device in an all-solid-state laser.

[0032] Beneficial effects of the present invention:

[0033] The inventors found that in the borate system, the π-conjugated (BO3) 3- The planar triangular groups have a wider band gap and a larger microscopic second-order polarizability, and their coplanar arrangement is conducive to the synthesis of nonlinear optical crystals with large band gaps and frequency doubling coefficients. (BO3) 3- The group is considered to be the most excellent nonlinear optically active group in borate, and the most representative crystal is KBe2BO3F2 (KBBF). The KBBF structure is a typical layered structure, and the weak interlayer force is the root cause of its severe layered growth habit. Structural modification based on the KBBF structure, including enhancing the interlayer force, is a hot spot for creating new nonlinear optical crystals. The present invention creatively uses (HTeO3) - The group is used as a linker to construct a 3- and (HTeO3) - A composite elementary compound of a group and a nonlinear optical crystal of the compound.

[0034] (1) The present invention provides a novel telluric acid boric acid composite Be2(BO3)(HTeO3) compound and its crystal, the crystal has a structural configuration similar to KBBF, and its crystal structure is composed of (BO3) 3- [Be2BO3O2] ∞ Layer and [HTeO3] ∞ Layers are stacked alternately; [Be2BO3O2] ∞ The layer is similar to the [Be2BO3F2] in the famous KBe2BO3F2 (KBBF) structure. ∞ The layers are very similar, within the layer (BO3) 3- The groups are arranged almost uniformly, contributing to the main nonlinear effect of the crystal. The special feature of the present invention is that the structure is formed by (HTeO3) - The group realizes [Be2BO3F2] ∞ The connection of the layers, i.e. (HTeO3) in the structure - The group and the adjacent [Be2BO3O2] ∞ Two opposite (BeO4) layers 6- The tetrahedra are connected by sharing dangling O atoms, [HTeO3] ∞ In-layer (HTeO3) - There is positional disorder around the c-axis of the group. The crystal has a frequency doubling effect comparable to that of KBBF and has the potential to be used in the ultraviolet to mid-infrared region; at the same time, the crystal does not absorb moisture and has excellent physical properties.

[0035] (2) The Be2(BO3)(HTeO3) crystal of the present invention outputs a strong 532nm light under 1064nm laser irradiation, and its powder frequency doubling effect is 1.24 times that of KH2PO4 (KDP), and phase matching can be achieved.

[0036] (3) The Be2(BO3)(HTeO3) crystal of the present invention has a wide light transmittance range, being transparent in the range of 0.3 to 5.5 μm, and having an ultraviolet cutoff edge of 239 nm. It can be applied to the ultraviolet-mid-infrared and far-infrared regions, and has potential application prospects in the fields of nonlinear optics, laser technology, electro-optic modulation, photorefractive information processing, and information storage.

[0037] (4) The physical and chemical properties of the Be2(BO3)(HTeO3) crystal of the present invention are stable.

[0038] (5) The preparation method of the Be2(BO3)(HTeO3) compound and crystal of the present invention has a simple process, a fast growth rate and a low cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Figure 1 It is a schematic diagram of the crystal structure of the Be2(BO3)(HTeO3) crystal of the present invention.

[0040] Figure 2 This is a comparison chart of the X-ray diffraction simulation spectrum obtained by fitting the crystal structure of the sample in Example 2 according to the single crystal X-ray diffraction data and the powder X-ray diffraction of the sample in Example 1.

[0041] Figure 3 It is a schematic diagram of frequency doubling test, wherein 1 is a laser, 2 is an incident laser beam, 3 is the Be2(BO3)(HTeO3) crystal of Example 3, 4 is the generated outgoing laser beam, and 5 is a photomultiplier tube equipped with a filter.

[0042] Figure 4 This is the frequency doubling test result of the sample in Example 2.

[0043] Figure 5 This is the UV-visible-near infrared diffuse reflectance diagram of the sample in Example 2.

[0044] Figure 6 This is the infrared spectrum of the sample in Example 2. DETAILED DESCRIPTION

[0045] The technical scheme of the present invention will be further described in detail below in conjunction with specific embodiments. It should be understood that the following embodiments are only exemplary descriptions and explanations 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 included in the scope that the present invention is intended to protect.

[0046] Unless otherwise specified, the raw materials and reagents used in the following examples are commercially available or can be prepared by known methods.

[0047] Example 1 Preparation of Be2(BO3)(HTeO3) Compound

[0048] Be2(BO3)(HTeO3) compound was prepared by the following steps:

[0049] (a) BeO (0.02 mol, 0.500 g), H3BO3 (0.01 mol, 0.618 g), TeO2 (0.01 mol, 1.596 g) and H2O (10 mL) were placed in a reactor with a polytetrafluoroethylene liner (25 mL), and the temperature was increased to 180 °C at a rate of 10 °C / h and kept at this temperature for 2 days;

[0050] (b) After the reaction is completed, the system is naturally cooled to room temperature, and Be2(BO3)(HTeO3) compound powder can be obtained after separation and drying.

[0051] Example 2 Preparation of Be2(BO3)(HTeO3) crystals

[0052] Be2(BO3)(HTeO3) crystals were prepared by the following steps:

[0053] (a) BeO (0.02 mol, 0.500 g), H3BO3 (0.05 mol, 3.092 g), TeO2 (0.01 mol, 1.596 g) and H2O (10 mL) were placed in a reactor with a polytetrafluoroethylene liner (25 mL), and the temperature was raised to 220 °C at a rate of 20 °C / h and crystallized at this temperature for 5 days;

[0054] (b) After the crystallization is completed, the reaction system is cooled to room temperature at a rate of 5°C / h. After separation and drying, Be2(BO3)(HTeO3) crystals can be obtained.

[0055] The structural diagram of the Be2(BO3)(HTeO3) crystal prepared in this embodiment is shown in FIG. Figure 1 As shown, the crystal

[0056] — in the hexagonal system, the space group is P62c, and the unit cell parameters are α=β=90°, γ=120, z=2.

[0057] Example 3 Preparation of Be2(BO3)(HTeO3) crystals

[0058] Be2(BO3)(HTeO3) crystals were prepared by the following steps:

[0059] (a) BeO (0.2 mol, 5.0 g), H3BO3 (0.5 mol, 30.9 g), TeO2 (0.1 mol, 15.96 g) and H2O (100 mL) were placed in a reactor with a polytetrafluoroethylene liner (250 mL), and the temperature was raised to 200 °C at a rate of 15 °C / h and crystallized at this temperature for 10 days;

[0060] (b) After the crystallization is completed, the reaction system is cooled to room temperature at a rate of 5°C / h. After separation and drying, Be2(BO3)(HTeO3) crystals can be obtained.

[0061] Example 4

[0062] Structural analysis and phase analysis of Be2(BO3)(HTeO3) crystals

[0063] The Be2(BO3)(HTeO3) crystal samples prepared in Examples 2-3 were analyzed by single crystal X-ray diffraction. Single crystal X-ray diffraction was performed on a Synergy Custom (Liquid Metal JetD2+) X-ray single crystal diffractometer of Rigaku Corporation, Japan. The data collection temperature was 293K, and the diffraction light source was Ga-Kα radiation ( ), the scanning mode was ω=2θ, and the data were processed by absorption correction using the Multi-Scan method. The structure analysis was completed using the SHELXTL program 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 F-based 2 The full matrix least squares method was used to refine the coordinates of all atoms and the anisotropic thermal parameters. The single crystal X-ray diffraction results showed that the chemical formula of the crystals prepared in Examples 2 to 3 was Be2(BO3)(HTeO3).

[0064] The phase obtained in Example 1 was analyzed by powder X-ray diffraction. Powder X-ray diffraction was performed on a Rigaku Miniflex II X-ray powder diffractometer. The test conditions were a fixed target monochromatic light source Cu-Kα, a wavelength of The scanning range is 5-80°, and the scanning step is 0.02°. The powder X-ray diffraction spectrum shows that the diffraction peak positions of the samples in Examples 1-3 are substantially the same. Figure 2 As shown, except for a trace amount of BeO raw material, the X-ray diffraction spectrum obtained by fitting the crystal structure of Example 2 is basically consistent with the peak position and intensity of the X-ray diffraction spectrum of the sample powder of Example 1. This shows that the Be2(BO3)(HTeO3) single crystal structure analysis prepared in the embodiment of the present invention is correct and the sample is relatively pure.

[0065] Example 5 Frequency doubling test experiment of Be2(BO3)(HTeO3) crystal

[0066] like Figure 3 As shown, a frequency doubling test experiment was performed on the Be2(BO3)(HTeO3) crystal sample obtained in Example 2. The 1064nm laser emitted by the Nd:YAG solid laser was used as the fundamental frequency light to irradiate the Be2(BO3)(HTeO3) crystal powder obtained in Example 2, and the generated frequency doubling light was detected by a photomultiplier tube, and the harmonic intensity was displayed by an oscilloscope. The specific method is as follows:

[0067] The crystal samples to be tested are sieved into particle sizes of 25-45 μm, 45-62 μm, 62-75 μm, 75-109 μm, 109-150 μm and 150-212 μm using a standard sieve. Figure 3 At position 3 in the device shown, at room temperature, a Q-switched Nd:YAG laser is used as the input light source (i.e., laser 1), and the incident wavelength of the incident laser beam 2 is 1064nm. After the incident laser beam 2 passes through the crystal 3 of Example 2, the frequency-doubled signal of the outgoing laser beam 4 after passing through the filter 5 is tested respectively, and the variation trend of the frequency-doubled signal with the particle size is observed to determine whether phase matching can be achieved. Under the same test conditions, KH2PO4 (KDP) is used as the reference for the double frequency test. The test results are shown in FIG. Figure 4 As shown, Figure 4 The results show that the powder frequency-doubled effect of Be2(BO3)(HTeO3) crystal under 1064nm laser irradiation is about 1.24 times that of KDP under the same conditions, and phase matching can be achieved.

[0068] Example 6 Spectral Performance Test of Be2(BO3)(HTeO3) Crystal

[0069] Taking the Be2(BO3)(HTeO3) crystal sample prepared in Example 2 as a representative, the UV diffuse reflectance spectrum test was conducted on the Lambda-950 UV-visible-near infrared spectrophotometer of Perkin-Elmer, USA, and the infrared spectrum test was conducted on the BrukerVERTEX 70 infrared spectrometer. The diffuse reflectance test was conducted using BaSO4 as a reference substrate for baseline test, and then the crystal sample of Example 2 was ground into powder and spread on BaSO4 for reflectance spectrum test. Figure 5 and Figure 6Shown are the UV-Vis-Near-Infrared diffuse reflectance diagram and infrared spectrum diagram of the Be2(BO3)(HTeO3) crystal sample prepared in Example 2. The results in the diagram indicate that the Be2(BO3)(HTeO3) prepared in the present invention has a wider light transmittance range, a very high transmittance in the spectral range of 0.3 to 5.5 μm, and an ultraviolet absorption cutoff wavelength of up to 239 nm. It can be further seen from the ultraviolet spectrum that the Be2(BO3)(HTeO3) crystal prepared in the present invention has a larger band gap of about 4.32 eV.

[0070] The above is an exemplary description of the embodiments of the present invention. However, the protection scope of the present invention is not limited to the above embodiments. Any modification, equivalent substitution, improvement, etc. made by those skilled in the art within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A compound, characterized in that Its chemical formula is Be2(BO3)(HTeO3).

2. The method for preparing the compound according to claim 1, characterized in that: The method comprises: mixing a Be-containing compound, a B-containing compound and a Te-containing compound, and preparing the compound by hydrothermal reaction.

3. The method according to claim 2, characterized in that The Be-containing compound is selected from at least one of BeO, BeSO4·4H2O or BeF2. Preferably, the B-containing compound is selected from at least one of H3BO3, B2O3, HBO2 and Li2B4O7. Preferably, the Te-containing compound is selected from TeO2 or H2TeO3. Preferably, in the Be-containing compound, the B-containing compound and the Te-containing compound, n(Be):n(B):n(Te)=(1-3):(1-6):(1-3).

4. The method according to claim 2, characterized in that: The reaction temperature of the hydrothermal reaction is 160-240° C., and the reaction time of the hydrothermal reaction is 1-3 days.

5. A nonlinear optical crystal, characterized in that: The chemical formula of the crystal is Be2(BO3)(HTeO3), that is, the nonlinear optical crystal is Be2(BO3)(HTeO3) crystal.

6. The crystal according to claim 5, characterized in that The nonlinear optical crystal belongs to six - The cubic system has a space group of P62c and unit cell parameters of α=β=90 o ,γ=120,z=2.

7. The crystal according to claim 5, characterized in that The nonlinear optical crystal is composed of honeycomb [Be2BO3O2] ∞ Layer and [HTeO3] ∞ The layers are stacked alternately.

8. The method for preparing the crystal according to any one of claims 5 to 7, characterized in that: The method comprises: The Be-containing compound, the B-containing compound and the Te-containing compound are mixed and heated for crystallization to obtain the crystal.

9. The method according to claim 8, characterized in that The temperature of the heating crystallization is 160-240° C., and the time of the heating crystallization is 3-15 days.

10. Application of the crystal according to any one of claims 5 to 7 in the fields of laser frequency doubling, electro-optic modulation, photorefractive information processing or information storage; preferably, used as a frequency doubling device in an all-solid-state laser.

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