Zinc borate crystal ammonified by fluoride, its preparing process and application
1. An ammono zinc fluoride borate crystal, which is characterized in that the chemical formula of the crystal is Zn2BO3F(NH3) Molecular weight of 225.66, belonging to hexagonal system, space group of P63mc, cell parameter ofZ＝2。
2. A process for the preparation of the crystals of zinc ammine fluoride borate according to claim 1, wherein the crystals are prepared by a hydrothermal method with programmed temperature control, by the following steps:
(a) ZnF is reacted with2And H3BO3Uniformly mixing according to the mol ratio of 1: 2-2: 1;
(b) transferring the mixture obtained in the step (a) into a polytetrafluoroethylene lining of a 25ml hydrothermal kettle, adding 1-4 ml of 25% -28% ammonia water and 2-6 ml of water, stirring to fully dissolve and uniformly mix the substances, and screwing and sealing the hydrothermal kettle;
(c) and (c) placing the hydrothermal kettle in the step (b) in a constant temperature box, heating to 180-230 ℃ at the speed of 50 ℃/h, keeping the temperature for 3-7 days, cooling to room temperature at the speed of 1-10 ℃/h, and opening the hydrothermal kettle to obtain the ammonified zinc fluoride crystal.
3. The nonlinear optical device formed from a zinc ammine fluoride borate crystal of claim 1, wherein at least one incident light wave passes through the zinc ammine fluoride borate crystal to produce an outgoing light wave having a frequency different from the incident light wave.
4. The nonlinear optical device in accordance with claim 3 wherein the nonlinear optical device comprises a frequency doubling generator, a frequency converter, and an optical parametric oscillator.
Background
The nonlinear optical crystal refers to a kind of functional material capable of generating nonlinear optical effect, which can change the frequency of laser, including frequency doubling, sum frequency, difference frequency, optical parametric oscillation and optical amplification. The laser can be subjected to frequency conversion through a nonlinear optical device made of a nonlinear optical crystal, so that the wavelength of the laser is expanded, and the application range of the laser is widened. Therefore, the nonlinear optical crystal has huge application in the technical field of laser.
With the development of laser technology and the advent of tunable lasers, nonlinear optical devices have been rapidly developed. Currently, the nonlinear optical crystal in practical use includes β -Ba2B2O4(BBO)、LiB3O5(LBO)、KTiOPO4(KTP) and KBe2BO3F2(KBBF) and the like. In particular to a KBBF crystal which is the only practical material for outputting deep ultraviolet coherent radiation by laser direct frequency doubling. The all-solid-state deep ultraviolet coherent light source has important application in many high-technology fields. Such as: the development of a new generation of laser circuit lithography requires a deep ultraviolet coherent light source; the high-end scientific research instrument and equipment manufactured by using the all-solid-state deep ultraviolet coherent light source obtains important results in the researches of graphene, high-temperature superconductivity, topological insulators, wide and modern semiconductors, catalysts and the like due to the precise performance front edge and indexes, so that the depth of material research is improved, and a new scientific research field is developed; the deep ultraviolet coherent light source can also greatly promote the development of the laser precision machining industry. However, the preparation of KBBF crystals involves a highly toxic Be element and is not environmentally friendly. Furthermore, the lamellar growth habit and long growth cycle of KBBF crystals limit the size of the crystals produced, preventing their further development and use. Therefore, it is necessary to search for a novel nonlinear optical crystal having a crystal structure similar to KBBF but containing no highly toxic Be element.
Disclosure of Invention
The invention aims to provide an ammonified zinc fluoride borate crystal which is characterized in thatThe chemical formula of the crystal is Zn2BO3F(NH3) Molecular weight of 225.66, belonging to hexagonal system, space group of P63mc, cell parameter of Z＝2。
The invention also aims to provide a preparation method of the ammonified zinc fluoride crystal, which utilizes a hydrothermal method and adopts a program temperature control mode to prepare the crystal.
It is a further object of the present invention to provide the use of the crystals of zinc ammine fluoride borate as non-linear optical devices.
The asymmetric structural element in the crystal structure of the zinc ammonium fluoride borate comprises two independent Zn atoms, an independent B atom, an independent O atom and an independent NH3A molecule. B forms [ BO ] with the adjacent O3]Planar triangular groups, two independent Zn atoms forming tetra-coordinated [ ZnO ] with adjacent O, F and N atoms3F]And [ ZnO ]3N]A group. [ BO ]3]、[ZnO3F]And [ ZnO ]3N]The groups share a common apical oxygen atom with each other to form a layered structure, similar to that of KBBF crystals composed of [ BO3]And [ BeO3F]A structured layered structure.
The preparation method of the zinc borate crystal through ammonification and fluorination adopts a hydrothermal method and is carried out through program temperature control, and the specific operation is carried out according to the following steps:
(a) ZnF is reacted with2And H3BO3Uniformly mixing according to the mol ratio of 1: 2-2: 1;
(b) transferring the mixture obtained in the step (a) into a polytetrafluoroethylene lining of a 25ml hydrothermal kettle, adding 1-4 ml of 25% -28% ammonia water and 2-6 ml of water, stirring to fully dissolve and uniformly mix the substances, and screwing and sealing the hydrothermal kettle;
(c) and (c) placing the hydrothermal kettle in the step (b) in a constant temperature box, heating to 180-230 ℃ at the speed of 50 ℃/h, keeping the temperature for 3-7 days, cooling to room temperature at the speed of 1-10 ℃/h, and opening the hydrothermal kettle to obtain the ammonified zinc fluoride crystal.
The zinc borate crystal has higher transmission in the ultraviolet-visible region within the range of 200-700nm, does not reach the transmission cut-off edge in the ultraviolet region, and has the powder frequency doubling efficiency of KH under the irradiation of 1064nm laser2PO4(KDP) 0.8 times the weight of the total composition.
ZnF in the invention2、H3BO3And the ammonia water can adopt the reagent and raw material sold in the market, and has the advantages of simple operation, short growth period, low cost, easy obtainment of large-size single crystals and the like.
The zinc borate crystal prepared by the invention is used for manufacturing nonlinear optical devices, including frequency doubling generators, frequency converters and optical parametric oscillators. The nonlinear optical device manufactured by the zinc ammonium fluoride borate crystal is characterized in that at least one light wave is incident to the zinc ammonium fluoride borate crystal, so that an emergent light wave with a frequency different from that of the incident light wave is generated.
Drawings
FIG. 1 shows an ammonolysis of zinc fluoroborate Zn2BO3F(NH3) Crystal of [ BO ]3]、[ZnO3F]And [ ZnO ]3N]The groups share oxygen atoms with each other to form a layered structure, which is schematically projected at the center of the ab plane.
FIG. 2 shows the ammonification of zinc fluoroborate Zn2BO3F(NH3) The projection of the stacking of crystal structures along the b-axis direction is schematically shown.
FIG. 3 shows the ammonification of zinc fluoroborate Zn2BO3F(NH3) Powder X-ray diffraction pattern of (a).
FIG. 4 is a schematic diagram of the operation of a typical non-linear optical device made from crystals of zinc ammine fluoride borate, wherein: 1 is a laser, 2 is an incident light wave, 3 is an ammonification zinc fluoride crystal, 4 is an emergent light wave, and 5 is a filter.
The diagram of fig. 4 is illustrated as follows: the laser 1 emits an incident light wave 2, the light wave is incident to the zinc ammonium fluoride borate crystal 3 to generate an emergent light wave 4, the emergent light wave comprises a light wave with a frequency different from that of the incident light wave 2, and the light wave with a different frequency can be separated by the optical filter 5.
Detailed Description
The present invention is further illustrated by the following specific examples.
EXAMPLE 1 growth of Zinc Aminofluorinated Borate crystals by hydrothermal method
0.31g of ZnF was weighed out separately2(3mmol) and 0.37g of H3BO3(6mmol), mixed in a mortar and ground well. And transferring the mixture into a polytetrafluoroethylene lining of a 25ml hydrothermal kettle, adding 1.5ml of ammonia water (with the concentration of 25-28%) and 6ml of water, stirring to fully dissolve and uniformly mix the substances, and screwing and sealing the hydrothermal kettle. And (3) placing the hydrothermal kettle in a constant temperature box, heating to 180 ℃ at the speed of 50 ℃/h, keeping the temperature for 7 days, cooling to room temperature at the speed of 1 ℃/h, and opening the hydrothermal kettle to obtain the ammonified zinc fluoride crystal.
EXAMPLE 2 growth of Zinc Aminofluorinated Borate crystals by hydrothermal method
0.62g of ZnF was weighed respectively2(6mmol) and 0.25g of H3BO3(4mmol), mixed in a mortar and ground well. And transferring the mixture into a polytetrafluoroethylene lining of a 25ml hydrothermal kettle, adding 4ml of ammonia water (the concentration is 25% -28%) and 2ml of water, stirring to fully dissolve and uniformly mix the substances, and screwing and sealing the hydrothermal kettle. And (3) placing the hydrothermal kettle in a constant temperature box, heating to 230 ℃ at the speed of 50 ℃/h, keeping the temperature for 3 days, cooling to room temperature at the speed of 5 ℃/h, and opening the hydrothermal kettle to obtain millimeter-grade zinc ammonium fluoride borate crystals, wherein the maximum crystal size can be 3mm multiplied by 2mm multiplied by 0.5 mm.
Example 3 Crystal Structure resolution of Aminofluorinated Zinc Borate
The samples of examples 1 and 2 were subjected to structural analysis by single crystal X-ray diffraction method. Wherein the single crystal X-ray diffraction is carried out on Gemini E type X-ray single crystal diffractometer of Agilent, USA, and the diffraction light source is Mo-K monochromatized by graphiteαRay of radiationThe scanning mode is omega, and data processing is carried out on the data by adopting a Multi-Scan method. Structural analysis adopts SHELX-2013 program, determines heavy atom position by direct method, obtains other atom coordinates by difference Fourier synthesis method, and uses F-based2The full matrix least square method refines the coordinates and anisotropic thermal parameters of all atoms.
Typical single crystal X-ray diffraction analysis results are as follows. The chemical formula of the crystal is Zn2BO3F(NH3) The name of the product is ammoniated zinc fluoborate, the molecular weight is 225.66, the product belongs to hexagonal system, and the space group is P63mc, cell parameter of And Z is 2. The asymmetric structural element in the crystal structure of the zinc ammonium fluoride borate comprises two independent Zn atoms, an independent B atom, an independent O atom and an independent NH3A molecule. B forms [ BO ] with the adjacent O3]Planar triangular groups, two independent Zn atoms forming tetra-coordinated [ ZnO ] with adjacent O, F and N atoms3F]And [ ZnO ]3N]A group of (1). [ BO ]3]、[ZnO3F]And [ ZnO ]3N]The groups share oxygen atoms with each other to form a layered structure, as shown in FIGS. 1 and 2, similar to that of KBBF crystal composed of [ BO [ ]3]And [ BeO3F]A structured layered structure.
Example 4 powder X-ray diffraction analysis of Zinc Aminofluorinated borate crystals
After grinding the zinc tetrafluoroborate ammine crystals obtained in examples 1 and 2, powder X-ray diffraction analysis was carried out on an Advance D8 powder diffractometer from Bruker, Germany, under the test conditions of Cu target KαLight sourceTube voltage and tube current of X-ray tube40kV and 40mA, the scanning range is 5-70 degrees, and the scanning step is 0.02 degree. The measurement results are shown in FIG. 3.
Example 5 frequency doubling experiment of Aminofluorinated Zinc Borate crystals
The zinc ammonium fluoride borate crystals obtained in examples 1-2 were placed at the position 3 as shown in FIG. 4. Using an Nd: the infrared laser with the wavelength of 1064nm emitted by the YAG pulse laser is used as an incident light wave to irradiate the zinc ammonium fluoride borate crystal, and a frequency doubling visible light wave with the wavelength of 532nm can be generated. FIG. 3 shows a graph consisting of Nd: the infrared laser with the wavelength of 1064nm emitted by the YAG pulse laser is used as an incident light wave 2 to irradiate the zinc ammonium fluoride borate crystal 3, and a frequency doubling light wave with the wavelength of 532nm can be generated. The emergent light wave 4 contains the original 1064nm incident light wave with unchanged frequency and the newly generated 532nm frequency doubling light wave. The original incident light wave with unchanged frequency can be filtered by the filter 5, and only 532nm frequency-doubled light wave passes through the filter.
