阅读说明：本技术 一种氟硼铝酸铯铷非线性光学晶体及其制备方法和用途 (Cesium rubidium fluoroboroaluminate nonlinear optical crystal and preparation method and application thereof ) 是由 王颖 刘红坤 于 2019-12-05 设计创作，主要内容包括：本发明提供了一种氟硼铝酸铯铷非线性光学晶体及其制备方法和用途,所述晶体的化学式为CsRbAl<Sub>2</Sub>(B<Sub>3</Sub>O<Sub>6</Sub>)<Sub>2</Sub>F<Sub>2</Sub>,晶体的分子量为567.19,所述晶体的结构属于六方晶系,空间群为<I>P-62c</I>,晶胞参数为<I>a(The invention provides a cesium rubidium fluoroboroaluminate nonlinear optical crystal and a preparation method and application thereof, wherein the chemical formula of the crystal is CsRbAl 2 (B 3 O 6 ) 2 F 2 The molecular weight of the crystal is 567.19, the structure of the crystal belongs to a hexagonal system, and the space group is P‑62c Cell parameter of a =b=6.9807Å， c =8.057Å， α = β =90°， γ =120 °, cell volume 340.02 Å 3 . The crystal can be prepared by adopting a pulling method or a high-temperature melt method. The nonlinear optical performance of the crystal is close to KBBF, and the crystal can be used for Nd: progressive frequency doubling generation of YAG (λ =1064 nm) lasers shorter than 200Harmonic light output at nm. In addition, the crystal of the invention has a single crystal structure, is colorless and transparent, has good thermal stability, can grow in air atmosphere without adopting highly toxic raw materials for synthesis, and has insignificant crystal layer growth habit.)

1. The cesium rubidium fluoroboroaluminate nonlinear optical crystal is characterized in that the chemical formula of the crystal is CsRbAl₂(B₃O₆)₂F₂The molecular weight of the crystal is 567.19, the structure of the crystal belongs to a hexagonal system, and the space group isP-62cCell parameter ofa=b= 6.9807 Å，c= 8.057 Å，α=β=90°，γ=120 °, cell volume 340.02 ų。

2. A method for preparing cesium rubidium fluoroboroaluminate nonlinear optical crystal of claim 1, characterized by comprising the steps of:

a. respectively weighing compounds containing Cs, Al, B, O and F as raw materials according to the molar ratio of the chemical formula;

b. mixing and grinding the raw materials, placing the mixture in a muffle furnace, heating to 500 ~ 650 ℃ for 24 ~ 96 hours for sintering, and cooling to room temperature after sintering to obtain cesium rubidium fluoroboroaluminate polycrystalline powder;

c. the crystal growth by the Czochralski method or the kyropoulos method comprises the following steps:

c-1, filling cesium rubidium fluoroborate aluminate polycrystalline powder into a platinum crucible, then placing the platinum crucible into a crystal furnace, heating to 660 ~ 800 ℃, keeping the temperature for 5 ~ 96 hours until the raw materials are completely and uniformly melted, and then rapidly cooling to 0.5 ~ 2 ℃ above the freezing point to obtain a melt, wherein the freezing point is 650 +/-5 ℃;

c-2, fixing seed crystals at the lower ends of the seed crystal rods, contacting the seed crystals with the liquid level of the melt, preheating for 1 ~ 10min, cooling to the freezing point or 0.1 ~ 1 ℃ below the freezing point, and starting crystal growth;

c-3, applying crystal transformation at 2 ~ 20rpm through a crystal growth controller, pulling the seed crystal at the speed of 0 ~ 10 mm/day, then slowly cooling at the speed of 0.1 ~ 5 ℃/day, after cooling, pulling the crystal away from the liquid level, and cooling to room temperature at the speed of 10 ~ 30 ℃/hour to obtain the cesium rubidium fluoroboroaluminate nonlinear optical crystal;

the method for growing the crystal by adopting the high-temperature molten salt method comprises the following steps:

c-1, putting cesium rubidium fluoroboroaluminate polycrystalline powder and a fluxing agent into a platinum crucible, then putting the platinum crucible into a crystal furnace, heating to 600 ~ 750 ℃, keeping the temperature for 5 ~ 96 hours until the raw materials are completely and uniformly melted, and then quickly cooling to 5 ~ 10 ℃ above a saturation point to obtain a mixed melt, wherein the temperature of the saturation point is 550 ~ 650 ℃ and 650 ℃ (different according to the types and the using amount of the fluxing agent);

c-2, fixing seed crystals at the lower ends of the seed crystal rods, contacting the seed crystals with the liquid level of the mixed melt, preheating for 1 ~ 10min, cooling to a saturation point, and starting crystal growth;

c-3, applying crystal transformation at 2 ~ 20rpm by a crystal growth controller, then slowly cooling at the speed of 0.1 ~ 5 ℃/day, lifting the crystal out of the liquid surface after cooling, and cooling to room temperature at the speed of 10 ~ 30 ℃/hour to obtain the cesium rubidium fluoroboroaluminate nonlinear optical crystal.

3. The method for preparing cesium rubidium fluoroboroaluminate nonlinear optical crystals according to claim 2, wherein in the step a, the Cs-containing compound is Cs₂CO₃、CsNO₃、CsHCO₃、CsOH、CH₃COOCs, CsF or CsBF₄(ii) a The Rb containing compound is Rb₂CO₃、RbNO₃、RbHCO₃、RbOH、CH₃COORb, RbF or RbBF₄(ii) a The Al-containing compound is Al₂O₃、Al(OH)₃Or (NH)₄)₃AlF₆(ii) a The compound containing B is H₃BO₃、B₂O₃Or CsBF₄(ii) a The F-containing compound being NH₄F、NH₄HF₂、CsF、RbF、HBF₄、RbBF₄、CsBF₄Or (NH)₄)₃AlF₆。

4. The method for preparing cesium rubidium fluoroboroaluminate nonlinear optical crystal according to claim 2, wherein the flux B is selected from the group consisting of₂O₃、H₃BO₃、CsF、RbF、(NH₄)₂AlF₆、PbF₂、NaF、NH₄F, the mol ratio of the cesium fluoroaluminate rubidium polycrystalline powder to the fluxing agentThe ratio was 1: 0.1 ~ 15.

5. Use of the cesium rubidium fluoroboroaluminate nonlinear optical crystal as claimed in claim 1, wherein the crystal is used for a frequency conversion device of a deep ultraviolet all-solid-state laser with an output light wavelength of less than 200 nm.

Technical Field

The invention relates to the technical field of photoelectron functional materials, in particular to a cesium rubidium fluoroborate aluminate nonlinear optical crystal and a preparation method and application thereof.

Background

Generated by multi-stage frequency conversion technology based on nonlinear optical crystalThe ultraviolet coherent light has the advantages of high efficiency, simple and compact structure, good output beam quality, long service life and the like, and has important application prospect in the high-technology fields of laser lithography, laser precision machining, photoelectron spectrometer, laser Raman spectrometer and the like and the field of advanced instrument manufacturing industry. The nonlinear optical crystal material suitable for ultraviolet/deep ultraviolet bands is a core material of an all-solid-state laser light source. In recent years, new nonlinear optical crystal materials have been discovered, but few have been able to meet commercial uv laser output. For a new nonlinear crystal material with excellent performance, the following requirements are generally required to be met: 1) effective nonlinear optical coefficients greater than 1 KDP, i.e.d _eff >d ₃₆(KDP) =0.39 pm/V; 2) a wide light transmission range and an ultraviolet cut-off edge of less than 200 nm; 3) moderate birefringence (Δ)n~ 0.08.08), 4) high laser damage threshold(s) ((R))>1 GW/cm²) (ii) a 5) Easy growth of large-size single crystal, stable physical and chemical properties, suitability for processing and the like. Currently, the only deep ultraviolet nonlinear optical crystal KBe capable of being practically applied₂BO₃F₂(KBBF), which satisfies the above-mentioned requirements 1 to 4, but has a lamellar growth habit, and it is difficult to obtain a large-sized crystal, which greatly limits its mass production and application. In addition, the KBBF raw material contains highly toxic beryllium oxide, which affects the industrial preparation of the KBBF raw material to a certain extent. Therefore, it is necessary to search for a new type of deep ultraviolet nonlinear optical crystal having excellent properties.

In the previous studies, there have been studies on alkali metal borate deep ultraviolet nonlinear crystals such as "cesium fluoroborate and cesium fluoroborate nonlinear optical crystals and methods of preparation and use" (patent application No. 201710215337.8), "Compound birefringent crystals of sodium fluoroborate and methods of preparation and use" (patent application No. 201610932882.4), "Compound nonlinear optical crystals of cesium rubidium fluoroborate and cesium fluoroborate and methods of preparation and use" (patent application No. 201710845438.3), and "Compound nonlinear optical crystals of cesium potassium fluoroborate and methods of preparation and use" (patent application Special publicationBy application number 201710845730.5), etc. The present invention differs from the above-mentioned studies in that B is simultaneously introduced into the crystal structure₃O₆Radical and AlO₃F group, no B-F bond, better thermal stability than the original fluoborate, high melting point (more than 650 ℃) and good crystal stability, and can be synthesized and grown in an open system. In contrast to the other earlier related patent "Compound Cesium fluoroboroaluminate and Cesium fluoroboroaluminate nonlinear optical Crystal" (patent application No. 201910688722.3), the compound CsRbAl of the present invention₂(B₃O₆)₂F₂Belonging to the hexagonal system with a space group ofP-62cThe molecular formula and crystal structure are completely different. The compound belongs to uniaxial crystal, has high symmetry, and is biaxial crystal (such as CsAlB) in crystal processing₃O₆F) Easier and more advantageous in practical application. In addition, the growth habit, the key parameters of the growth process, the linear and nonlinear optical properties of the crystal and the like are different from those of the former. The compounds of the present invention are not simple isomorphic substitutions for known compounds.

Disclosure of Invention

The invention aims to provide a cesium rubidium fluoroboroaluminate nonlinear optical crystal, a preparation method and application thereof, and aims to solve the problem that the comprehensive performance of the conventional nonlinear optical crystal is not ideal.

The purpose of the invention is realized by the following technical scheme: a cesium rubidium fluoroboroaluminate nonlinear optical crystal has a chemical formula of CsRbAl₂(B₃O₆)₂F₂CRABF for short, the molecular weight of the crystal is 567.19, the structure of the crystal belongs to a hexagonal system, and the space group isP-62cCell parameter ofa=b= 6.9807 Å，c= 8.057 Å，α=β=90°，γ=120 °, cell volume 340.02 ų。

The preparation method of the cesium rubidium fluoroboroaluminate nonlinear optical crystal comprises the following steps:

a. respectively weighing compounds containing Cs, Al, B, O and F as raw materials according to the molar ratio of the chemical formula;

b. mixing and grinding the raw materials, placing the mixture in a muffle furnace, heating to 500 ~ 650 ℃ for 24 ~ 96 hours for sintering, and cooling to room temperature after sintering to obtain cesium rubidium fluoroboroaluminate polycrystalline powder;

c. the crystal growth by the Czochralski method or the kyropoulos method comprises the following steps:

c-1, filling cesium rubidium fluoroborate aluminate polycrystalline powder into a platinum crucible, then placing the platinum crucible into a crystal furnace, heating to 650 ~ 800 ℃, keeping the temperature for 5 ~ 96 hours until the raw materials are completely and uniformly melted, and then rapidly cooling to 0.5 ~ 2 ℃ above the freezing point to obtain a melt, wherein the freezing point is 650 +/-5 ℃;

c-2, fixing seed crystals at the lower ends of the seed crystal rods, contacting the seed crystals with the liquid level of the melt, preheating for 1 ~ 10min, cooling to the freezing point or 0.1 ~ 1 ℃ below the freezing point, and starting crystal growth;

c-3, applying crystal rotation of 2 ~ 20rpm through a crystal growth controller, pulling the seed crystal at the speed of 0 ~ 10 mm/day (including pulling or not pulling, namely the kyropoulos method), then slowly cooling at the speed of 0.1 ~ 5 ℃/day, after cooling, pulling the crystal away from the liquid level, and cooling to room temperature at the speed of 10 ~ 30 ℃/hour to obtain the cesium rubidium fluoroborate aluminate nonlinear optical crystal;

the method for growing the crystal by adopting the high-temperature molten salt method comprises the following steps:

c-1, putting cesium rubidium fluoroboroaluminate polycrystalline powder and a fluxing agent into a platinum crucible, then putting the platinum crucible into a crystal furnace, heating to 600 ~ 750 ℃, keeping the temperature for 5 ~ 96 hours until the raw materials are completely and uniformly melted, and then quickly cooling to 5 ~ 10 ℃ above a saturation point to obtain a mixed melt, wherein the temperature of the saturation point is 550 ~ 650 ℃ and 650 ℃ (different according to the types and the using amount of the fluxing agent);

c-2, fixing seed crystals at the lower ends of the seed crystal rods, contacting the seed crystals with the liquid level of the mixed melt, preheating for 1 ~ 10min, cooling to a saturation point, and starting crystal growth;

c-3, applying crystal transformation at 2 ~ 20rpm by a crystal growth controller, then slowly cooling at the speed of 0.1 ~ 5 ℃/day, lifting the crystal out of the liquid surface after cooling, and cooling to room temperature at the speed of 10 ~ 30 ℃/hour to obtain the cesium rubidium fluoroboroaluminate nonlinear optical crystal.

In step aThe compound containing Cs is Cs₂CO₃、CsNO₃、CsHCO₃、CsOH、CH₃COOCs, CsF or CsBF₄(ii) a The Rb containing compound is Rb₂CO₃、RbNO₃、RbHCO₃、RbOH、CH₃COORb, RbF or RbBF₄(ii) a The Al-containing compound is Al₂O₃、Al(OH)₃Or (NH)₄)₃AlF₆(ii) a The compound containing B is H₃BO₃、B₂O₃Or CsBF₄(ii) a The F-containing compound being NH₄F、NH₄HF₂、CsF、RbF、HBF₄、RbBF₄、CsBF₄Or (NH)₄)₃AlF₆。

The fluxing agent B₂O₃、H₃BO₃、CsF、RbF、(NH₄)₂AlF₆、PbF₂、NaF、NH₄F, and the molar ratio of the cesium fluoride aluminate rubidium polycrystalline powder to the fluxing agent is 1: 0.1 ~ 15.

In the method for preparing the cesium rubidium fluoroboroaluminate nonlinear optical crystal, when a melt is prepared, a Cs-containing compound, an Rb-containing compound, an Al-containing compound, a B-containing compound and an F-containing compound can be directly weighed to replace the used cesium rubidium fluoroboroaluminate polycrystalline powder, and the compounds are weighed and uniformly mixed according to the molar ratio of Cs to Rb to Al to B to F of 0.5 ~ 3 to 0.5 ~ 3 to 0.5 ~ 10 to 1 ~ 20 to 0.5 ~ 20.

The cesium rubidium fluoroboroaluminate nonlinear optical crystal is used for generating harmonic light output of 2 frequency multiplication, 3 frequency multiplication, 4 frequency multiplication, 5 frequency multiplication or 6 frequency multiplication for laser beams with the wavelength of 1064 nm.

The cesium rubidium boroaluminate nonlinear optical crystal is used for harmonic generators, optical parametric and amplification devices or optical waveguide devices in deep ultraviolet regions.

The cesium rubidium fluoroboroaluminate nonlinear optical crystal is used for optical parametric and amplification devices from infrared to deep ultraviolet regions.

The cesium rubidium fluoroboroaluminate nonlinear optical crystal is applied to frequency conversion in a deep ultraviolet all-solid-state laser with the output light wavelength lower than 200 nm.

The nonlinear optical crystal has stronger nonlinear optical effect, and the powder frequency doubling test shows that the powder frequency doubling effect of the nonlinear optical crystal is about 2 times that of commercial crystal KH₂PO₄(see FIG. 3); the ultraviolet cut-off edge is shorter than 190 nm. In addition, the nonlinear optical performance of the crystal is close to KBBF, and the crystal can be used for Nd: progressive frequency multiplication of YAG (λ =1064 nm) lasers produces harmonic light outputs shorter than 200 nm. Furthermore, the crystal of the invention has a single crystal structure, is colorless and transparent, is stable in air, has good thermal stability (the melting point is more than 650 ℃), can grow in air atmosphere without adopting highly toxic raw materials, and has insignificant crystal layer growth habit.

The nonlinear optical crystal of the present invention has excellent optical properties in combination with B having a large nonlinear coefficient₃O₆Radical and asymmetric AlO₃The F group can balance multiple standards required by the deep ultraviolet nonlinear optical crystal material. On the one hand the conjugated group B₃O₆Can provide large nonlinear effect and large birefringence, and on the other hand, AlO₃The F group plays a role in eliminating a terminal oxygen atom dangling bond, increases the ultraviolet transmission range of the crystal and can meet the use requirement of the nonlinear optical crystal from an infrared region to a deep ultraviolet region. Therefore, the cesium rubidium fluoroboroaluminate nonlinear optical crystal has the advantages of wide ultraviolet transmission range, large nonlinear effect and large birefringence.

Compared with the existing KBBF crystal, the nonlinear optical performance is close, but the interlayer spacing of the cesium-rubidium fluoroborate aluminate nonlinear optical crystal is obviously shortened, the layered growth habit is improved, and BeO virulent raw materials are not needed. Compared with the deep ultraviolet nonlinear crystal of the alkali metal/alkaline earth metal fluoborate mentioned in other patents in the prior period, the crystal of the invention has good thermal stability and can grow in an open system. The preparation method can obtain centimeter-level crystals, and the nonlinear optical crystals with corresponding large sizes can be obtained by using a large-size crucible or container and prolonging the growth period of the crystals, and the crystals are transparent and have no package, so the preparation method has the advantages of high growth speed, low cost, easiness in obtaining large-size crystals and the like.

Drawings

FIG. 1 is a schematic diagram of the structure of a cesium rubidium fluoroboroaluminate nonlinear optical crystal.

FIG. 2 is an XRD ray diffraction pattern of cesium rubidium fluoroboroaluminate nonlinear optical crystal after grinding into powder.

FIG. 3 is a graph comparing frequency doubling measurements of cesium rubidium fluoroboroaluminate nonlinear optical crystals with KDP.

Fig. 4 is a typical schematic diagram of a nonlinear optical effect when a cesium rubidium fluoroboroaluminate nonlinear optical crystal is applied as a frequency doubling crystal, wherein 1 is a laser, 2 is a focusing prism, 3 is a processed cesium rubidium fluoroboroaluminate crystal, 4 is a beam splitter prism, and 5 is a narrow-band filter.

Detailed Description

The present invention will be described in detail with reference to specific examples. The following examples are not intended to limit the scope of the present invention, and any modifications made on the basis of the present invention do not depart from the spirit of the present invention. The raw materials or equipment used in the present invention are commercially available unless otherwise specified. The process conditions not mentioned in the present invention are carried out according to the conventional operations of the prior art.