Series of Alkali Metal Borophosphates Compounds, and Alkali Metal Borophosphates Nonlinear Optical Crystals as well as Preparation Method and Application thereof

Abstract

The present invention relates to compounds and their nonlinear optical (NLO) crystals of A.sub.3B.sub.11P.sub.2O.sub.23 (A=K, Rb, Cs, NH.sub.4), their producing method and uses thereof. The series of compounds have a chemical formula of A.sub.3B.sub.11P.sub.2O.sub.23 (A=K, Rb, Cs, NH.sub.4), which are namely K.sub.3B.sub.11P.sub.2O.sub.23, Rb.sub.3B.sub.11P.sub.2O.sub.23, Cs.sub.3B.sub.11P.sub.2O.sub.23 and (NH.sub.4).sub.3B.sub.11P.sub.2O.sub.23. The series of NLO crystals having the chemical formula of A.sub.3B.sub.11P.sub.2O.sub.23 (A=K, Rb, Cs, NH.sub.4), belong to rhombohedral crystal system, and have a space group of R3, crystal cell parameters of a=b=10.016(5)-12.591(5) , c=12.105(6)-14.905(6) , Z=3. A.sub.3B.sub.11P.sub.2O.sub.23 (A=K, Rb, Cs, NH.sub.4) compounds were prepared by a solid-state reaction method or a hydrothermal method, and A.sub.3B.sub.11P.sub.2O.sub.23 (A=K, Rb, Cs, NH.sub.4) NLO crystals were prepared by a high-temperature solid-state reaction method, a hydrothermal method, or a solution method. T They meet the requirements for the frequency conversion of UV wavelength lasers and could be used to prepare nonlinear optical devices.

Claims

1. A series of alkali metal borophosphates compounds, having a chemical formula of A.sub.3B.sub.11P.sub.2O.sub.23 (A=K, Rb, Cs, NH.sub.4), i.e. K.sub.3B.sub.11P.sub.2O.sub.23, Rb.sub.3B.sub.11P.sub.2O.sub.23, Cs.sub.3B.sub.11P.sub.2O.sub.23, and (NH.sub.4).sub.3B.sub.11P.sub.2O.sub.23, in which the molecular weights are 666.15, 805.26, 947.57 and 602.97, respectively.

2. A method for synthesizing the compounds as claimed in claim 1, the series of alkali metal borophosphates compounds were synthesized by conventional solid-state reaction methods, or a hydrothermal method.

3. The synthesizing method for the series of alkali metal borophosphates compounds as claimed in claim 2, comprising the following steps: the solid-state reaction method is used to prepare A.sub.3B.sub.11P.sub.2O.sub.23, wherein A=K, Rb, Cs, NH.sub.4 compounds, comprising the following steps: A mixture of a A-containing compound (A=K, Rb, Cs, NH.sub.4), a boron-containing compound, a phosphorus-containing compound was thoroughly ground. Then, the mixture was put into a muffle furnace for calcination, with several intermediate grindings to get the A.sub.3B.sub.11P.sub.2O.sub.23 (A=K, Rb, Cs, NH.sub.4) single phase polycrystalline powder, wherein the element A=K, Rb, Cs, NH.sub.4 in the A-containing compounds, the element boron in the boron-containing compounds, and the element phosphorus in the phosphorus-containing compounds are in a molar ratio of 2.5-3.5:10.5-11.5:1.5-2.5; the hydrothermal method is used to prepare A.sub.3B.sub.11P.sub.2O.sub.23, wherein A=K, Rb, Cs, NH.sub.4 compounds, comprising the following steps: A mixture of a A-containing compound (A=K, Rb, Cs, NH.sub.4), a boron-containing compound, a phosphorus-containing compound was combined with deionized water (0.1-50 mL) or mineralizer 0.1-50 g, wherein element A=K, Rb, Cs, NH.sub.4 in the A-containing compound, elemental boron in the boron-containing compound, and elemental phosphorus in the phosphorus-containing compound are in a molar ratio of 1-4:10-12:1-3; The mixture was loaded into Teflon-lined autoclave and subsequently sealed; The autoclave was heated, and then cooled to room temperature; Finally, filter the solution containing crystals to obtain the transparent alkali metal borophosphates compounds; the A-containing compounds (A=K, Rb, Cs, NH.sub.4) include at least one of AOH, A.sub.2O and alkali metal salt; alkali metal salt includes at least one of AF, ACl, ABr, ANO.sub.3, A.sub.2C.sub.2O.sub.4, A.sub.2CO.sub.3, AHCO.sub.3, A.sub.2SO.sub.4, wherein A=K, Rb, Cs, NH.sub.4; the boron containing compounds include at least one of B.sub.2O.sub.3, H.sub.3BO.sub.3 and boron salt; the boron salt includes at least one of ABO.sub.2, ABO.sub.3, A.sub.3BO.sub.3, A.sub.2B.sub.4O.sub.7, wherein A=K, Rb, Cs, NH.sub.4; the phosphorus containing compounds include at least one of P.sub.2O.sub.5, H.sub.3PO.sub.4 and phosphorus salt; the phosphorus salt includes at least one of AH.sub.2PO.sub.4, A.sub.2HPO.sub.4, A.sub.3PO.sub.4, A.sub.2H.sub.2P.sub.2O.sub.7, A.sub.4P.sub.2O.sub.7 wherein A=K, Rb, Cs, NH.sub.4.

4. The alkali metal borophosphates nonlinear optical crystals having a chemical formula of A.sub.3B.sub.11P.sub.2O.sub.23 (A=K, Rb, Cs, NH.sub.4), i.e. K.sub.3B.sub.11P.sub.2O.sub.23, Rb.sub.3B.sub.11P.sub.2O.sub.23, Cs.sub.3B.sub.11P.sub.2O.sub.23, and (NH.sub.4).sub.3B.sub.11P.sub.2O.sub.23, respectively, which belong to rhombohedral crystal system, and have a space group of R3 with unit-cell parameters a=b=10.016(5)-12.591(5) , c=12.105(6)-14.905(6) , Z=3.

5. A method for synthesizing the alkali metal nonlinear optical crystals as claimed in claim 4, the series of alkali metal borophosphates nonlinear optical crystals were synthesized by a high-temperature solid-state reaction method, a hydrothermal method, or a solution method.

6. The growth method for the series of alkali metal borophosphates nonlinear optical crystals as claimed in claim 5, based on the following operation steps: the high-temperature solid-state reaction method is used to prepare A.sub.3B.sub.11P.sub.2O.sub.23, wherein A=K, Rb, Cs, NH.sub.4 compounds, comprising the following steps: A.sub.3B.sub.11P.sub.2O.sub.23 (A=K, Rb, Cs, NH.sub.4) compounds or a mixture of the A.sub.3B.sub.11P.sub.2O.sub.23 (A=K, Rb, Cs, NH.sub.4) compounds with fluxing agent is heated to obtain a mixed melt. Or directly heat the mixture of the A-containing compound (A=K, Rb, Cs, NH.sub.4), boron-containing compound and phosphorus-containing compound or the mixture of A-containing compound (A=K, Rb, Cs, NH.sub.4), boron-containing compound, phosphorus-containing compound and fluxing agents to obtain a mixed melt. The crucible of the liquid is placed in the crystal growth furnace to cool down the temperature, and then the seed rod is lifted out of the liquid surface before the melt solidifies to obtain the seed crystal; the seed crystal is fixed on the seed rod, and the seed crystal is brought down to the liquid surface of the mixed melt or in the mixed melt for melting back to the saturation temperature; cooling or constant temperature growth. Finally, alkali metal borophosphates A.sub.3B.sub.11P.sub.2O.sub.23 (A=K, Rb, Cs, NH.sub.4) nonlinear optical crystals were prepared; the hydrothermal method is used to prepare A.sub.3B.sub.11P.sub.2O.sub.23, wherein A=K, Rb, Cs, NH.sub.4 compounds, comprising the following steps: A.sub.3B.sub.11P.sub.2O.sub.23 (A=K, Rb, Cs, NH.sub.4) compounds or a mixture of the A.sub.3B.sub.11P.sub.2O.sub.23 (A=K, Rb, Cs, NH.sub.4) compounds with mineralizer; Or directly mixing the A-containing compound (A=K, Rb, Cs, NH.sub.4), boron-containing compound and phosphorus-containing compound or the mixture of A-containing compound (A=K, Rb, Cs, NH.sub.4), boron-containing compound, phosphorus-containing compound and mineralizer to obtain a mixed melt. The mixture was combined with deionized water, and loaded into Teflon-lined autoclave; The autoclave was heated, and then cooled to room temperature; Finally, filter the solution containing crystals to obtain the transparent alkali metal borophosphates A.sub.3B.sub.11P.sub.2O.sub.23 (A=K, Rb, Cs, NH.sub.4) nonlinear optical crystals; the solution method is used to prepare A.sub.3B.sub.11P.sub.2O.sub.23, wherein A=K, Rb, Cs, NH.sub.4 compounds, comprising the following steps: A.sub.3B.sub.11P.sub.2O.sub.23 (A=K, Rb, Cs, NH.sub.4) compounds or a mixture of the A.sub.3B.sub.11P.sub.2O.sub.23 (A=K, Rb, Cs, NH.sub.4) compounds with cosolvent; Or directly mixing the A-containing compound (A=K, Rb, Cs, NH.sub.4), boron-containing compound and phosphorus-containing compound or the mixture of A-containing compound (A=K, Rb, Cs, NH.sub.4), boron-containing compound, phosphorus-containing compound and cosolvent to obtain a mixed melt. Then, the mixture was dissolved in deionized water and placed in a beaker stirred until dissolved completely. Then put the beaker on the heating table to heat for a period of time, the series of alkali metal borophosphates nonlinear optical crystals are obtained. In order to further grow them, the seed crystals of the series of crystals were suspended in solution with fine platinum wires. In order to reduce the evaporation of water, the beaker is covered with a layer of polyethylene plate and pierced with dozens of millimeter sized holes. After a period of time, take out a centimeter size alkali metal borophosphates A.sub.3B.sub.11P.sub.2O.sub.23 (A=K, Rb, Cs, NH.sub.4) nonlinear optical crystals from the solution.

7. The crystal growth method according to claim 6, based on the following specific operation steps: the high-temperature solid-state reaction method is used to prepare A.sub.3B.sub.11P.sub.2O.sub.23, wherein A=K, Rb, Cs, NH.sub.4 nonlinear optical crystals. The series of alkali metal borophosphates compounds and the fluxing agent are in a ratio of 1:0-20; or a molar ratio of a A-containing compound (A=K, Rb, Cs, NH.sub.4), a boron-containing compound, a phosphorus-containing compound and a fluxing agent is 2.5-3.5:10.5-11.5:1.5-2.5:0-20; The fluxing agents mainly include at least one or more of alkali metal salts, i.e., alkali metal carbonates, alkali metal nitrates, alkali metal sulfates, alkali metal oxalates, alkali metal borates, alkali metal phosphates, alkali metal halides, alkali metal fluoroborates, alkali metal metaborates, and alkali metal oxides, alkali metal hydroxides, and monohydrogen phosphates, dihydrogen phosphates, boron oxide, boric acid, phosphoric acid, lead oxide, lead fluoride, molybdenum oxide, bismuth oxide; the hydrothermal method is used to prepare A.sub.3B.sub.11P.sub.2O.sub.23, wherein A=K, Rb, Cs, NH.sub.4 nonlinear optical crystals. The series of alkali metal borophosphates compounds and the mineralizer are in a ratio of 1:0-10; or a molar ratio of a A-containing compound (A=K, Rb, Cs, NH.sub.4), a boron-containing compound, a phosphorus-containing compound and a fluxing agent is 2-4:10-12:1-3:0-10; the mineralizer include at least one or more of AOH, A.sub.2O, AF, ACl, ABr, ABF.sub.4, A.sub.3PO.sub.4, A.sub.3BO.sub.3, ANO.sub.3, A.sub.2C.sub.2O.sub.4 A.sub.2CO.sub.3, AHCO.sub.3, A.sub.2SO.sub.4, A.sub.2HPO.sub.4, AH.sub.2PO.sub.4, B.sub.2O.sub.3, wherein A=K, Rb, Cs, NH.sub.4; the solution method is used to prepare A.sub.3B.sub.11P.sub.2O.sub.23, wherein A=K, Rb, Cs, NH.sub.4 nonlinear optical crystals. The series of alkali metal borophosphates compounds and the cosolvent are in a ratio of 1:0-30; or a molar ratio of a A-containing compound (A=K, Rb, Cs, NH.sub.4), a boron-containing compound, a phosphorus-containing compound and a fluxing agent is 2.5-3.5:10.5-11.5:1.5-2.5:0-30; Cosolvents are self-cosolvents.

8. The use as claimed in claim 4, wherein said nonlinear optical crystals, A.sub.3B.sub.11P.sub.2O.sub.23 (A=K, Rb, Cs, NH.sub.4) can be used as frequency converting apparatus, which generates a second, third, fourth or fifth harmonic of a 1064-nm Nd:YAG laser.

9. The use as claimed in claim 4, wherein said nonlinear optical crystals, A.sub.3B.sub.11P.sub.2O.sub.23 (A=K, Rb, Cs, NH.sub.4) can be used in the preparation of multi-band frequency doubling devices or optics.

10. The use as claimed in claim 4, wherein said nonlinear optical crystals can be used as the second harmonic generator, the upper and lower frequency converters, optical parametric oscillator from infrared to ultraviolet.

Description

BRIEF DESCRIPTION OF THE FIGURES

[0047] FIG. 1 is an X-ray powder diffraction pattern of a compound Rb.sub.3B.sub.11P.sub.2O.sub.23 of the present invention;

[0048] FIG. 2 is an X-ray powder diffraction pattern of a compound Cs.sub.3B.sub.11P.sub.2O.sub.23 of the present invention;

[0049] FIG. 3 is a structural diagram of a A.sub.3B.sub.11P.sub.2O.sub.23 (A=K, Rb, Cs, NH.sub.4) crystal of the present invention;

[0050] FIG. 4 is a working schematic diagram of a nonlinear optical apparatus manufactured from A.sub.3B.sub.11P.sub.2O.sub.23 (A=K, Rb, Cs, NH.sub.4) crystal of the present invention, where 1 is the laser generator, 2 is the incident laser beam, 3 is post-treated and optically fabricated A.sub.3B.sub.11P.sub.2O.sub.23 (A=K, Rb, Cs, NH.sub.4) NLO devices, 4 is a output beam and 5 is a filter.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0051] The present invention is described above through specific embodiments, but the invention is not limited to these embodiments.

Embodiment 1

[0052] A.sub.3B.sub.11P.sub.2O.sub.23 (A=K, Rb, Cs, NH.sub.4) polycrystalline powder was prepared according to a reaction formula: 3A.sub.2CO.sub.3 (A=K, Rb, Cs, NH.sub.4)+22H.sub.3BO.sub.3+4NH.sub.4H.sub.2PO.sub.4.fwdarw.2A.sub.3B.sub.11P.sub.2O.sub.23 (A=K, Rb, Cs, NH.sub.4)+39H.sub.2O+3CO.sub.2+4NH.sub.3 as follows:

[0053] Reagents were weighed according to stoichiometric proportion and were put in a mortar, and then mixed and ground carefully. The mixture was put in a lidless corundum crucible of size of (100 mm100 mm. The said crucible was put into a muffle furnace, heated to 350 C. slowly and held at this temperature for 24 hours. After being cooled down, the loose and porous sample was taken out of the crucible and was once again mixed thoroughly, ground and put back to the crucible and compacted. The mixture was heated at 550 C. for 24 h and cooled to room temperature. The sample was then taken out and ground thoroughly, and the mixture was put back to the crucible and heated at 550 C. for 48 h. The product was analyzed by the powder X-ray diffraction of the product, where the X-ray diffraction pattern was consistent with a theoretical X-ray diffraction pattern of A.sub.3B.sub.11P.sub.2O.sub.23 (A=K, Rb, Cs, NH.sub.4) analyzed by a single-crystal structure.

[0054] Then, the single-phase polycrystalline powder was put into a (80 mm80 mm lidless platinum crucible which was placed in the center of a vertical, programmable temperature furnace, was heated at 850 C. until the melt became transparent and clear, held at this temperature for 15 h, and then quickly cooled to the initial crystallization temperature (650 C.). Then, a platinum wire was promptly dipped into the solution. The temperature was decreased at a rate of 0.5 C./h, then the platinum wire was pulled out of the solution, and allowed to cool to room temperature at a rate of 10 C./h.

[0055] Thus, a few colorless, transparent plate crystals crystallized on the platinum wire. The obtained crystals could be used as seeds. A seed crystal of A.sub.3B.sub.11P.sub.2O.sub.23 (A=K, Rb, Cs, NH.sub.4) was attached with Pt wire to a Pt rod and then suspended on solution at 600 C. for a quarter. The seed crystal was kept at this temperature in solution for half an hour while rotating at a rate of 10 rpm. The temperature of the furnace was first lowered quickly to 550 C. and then lowered at a rate of 2 C./day. After the growth of crystal ended, the crystal was lifted out of liquid surface. The temperature of the crystal was then lowered to room temperature at a rate of 10 C./h. As a result, transparent A.sub.3B.sub.11P.sub.2O.sub.23 (A=K, Rb, Cs, NH.sub.4) crystal with a size of 56 mm40 mm30 mm was obtained.

Embodiment 2

[0056] A.sub.3B.sub.11P.sub.2O.sub.23 (A=K, Rb, Cs, NH.sub.4) polycrystalline powder was prepared according to a reaction formula: 3AOH (A=K, Rb, Cs, NH.sub.4)+11H.sub.3BO.sub.3+P.sub.2O.sub.5.fwdarw.A.sub.3B.sub.11P.sub.2O.sub.23 (A=K, Rb, Cs, NH.sub.4)+18H.sub.2O as follows:

[0057] Reagents were weighed according to stoichiometric proportion, preparation of A.sub.3B.sub.11P.sub.2O.sub.23 (A=K, Rb, Cs, NH.sub.4) crystal by fluxing agent method: AOH (A=K, Rb, Cs, NH.sub.4)P.sub.2O.sub.5 as the fluxing agent system, the said reagents are used as the solute with the molar ratio of solute:fluxing agent=1:4, the molar ratio of AOH (A=K, Rb, Cs, NH.sub.4)/P.sub.2O.sub.5 was selected at 3/5. Then, mixed the said reagents with fluxing agent and put into a 80 mm80 mm lidless platinum crucible which was placed in the center of a vertical, programmable temperature furnace, was heated at 800 C., held at this temperature for 60 h, and then quickly cooled to the initial crystallization temperature (750 C.).

[0058] The temperature was decreased to room temperature at a rate of 1.5 C./h to obtain the seeds.

[0059] A seed crystal of A.sub.3B.sub.11P.sub.2O.sub.23 (A=K, Rb, Cs, NH.sub.4) was attached with Pt wire to a Pt rod and then suspended on solution at 700 C. for ten minutes. The seed crystal was kept at this temperature in solution for half an hour while rotating at a rate of 10 rpm. The temperature of the furnace was first lowered quickly to 600 C. and then lowered at a rate of 1 C./day. After the growth of crystal ended, the crystal was lifted out of liquid surface. The temperature of the crystal was then lowered to room temperature at a rate of 20 C./h. As a result, transparent A.sub.3B.sub.11P.sub.2O.sub.23 (A=K, Rb, Cs, NH.sub.4) crystal with a size of 36 mm22 mm15 mm was obtained.

Embodiment 3

[0060] A.sub.3B.sub.11P.sub.2O.sub.23 (A=K, Rb, Cs, NH.sub.4) polycrystalline powder was prepared according to a reaction formula: 3A.sub.2CO.sub.3 (A=K, Rb, Cs, NH.sub.4)+22H.sub.3BO.sub.3+2P.sub.2O.sub.5.fwdarw.2A.sub.3B.sub.11P.sub.2O.sub.23 (A=K, Rb, Cs, NH.sub.4)+33H.sub.2O+3CO.sub.2 as follows:

[0061] The said polycrystalline A.sub.3B.sub.11P.sub.2O.sub.23 (A=K, Rb, Cs, NH.sub.4) is used as the solute with the molar ratio of solute:fluxing agent (H.sub.3BO.sub.3P.sub.2O.sub.5)=1:3. Then, mixed homogeneously and put into a 80 mm80 mm lidless platinum crucible which was placed in the center of a vertical, programmable temperature furnace, was heated at 350 C. until the melt became transparent and clear, held at this temperature for 60 h, and then quickly cooled to the initial crystallization temperature (330 C.).

[0062] The temperature was decreased to room temperature at a rate of 3.5 C./h to obtain the seeds.

[0063] A seed crystal of A.sub.3B.sub.11P.sub.2O.sub.23 (A=K, Rb, Cs, NH.sub.4) was attached with Pt wire to a Pt rod and then suspended on solution for 15 minutes. The seed crystal was kept at this temperature in solution for twenty minutes while rotating at a rate of 5 rpm. The temperature of the furnace was first lowered quickly to 315 C. and then lowered at a rate of 3 C./day.

[0064] After the growth of crystal ended, the crystal was lifted out of liquid surface. The temperature of the crystal was then lowered to room temperature at a rate of 1 C./h. As a result, transparent A.sub.3B.sub.11P.sub.2O.sub.23 (A=K, Rb, Cs, NH.sub.4) crystal with a size of 25 mm24 mm10 mm was obtained.

Embodiment 4

[0065] A.sub.3B.sub.11P.sub.2O.sub.23 (A=K, Rb, Cs, NH.sub.4) polycrystalline powder was prepared according to a reaction formula: 3A.sub.2O (A=K, Rb, Cs, NH.sub.4)+22H.sub.3BO.sub.3+2P.sub.2O.sub.5.fwdarw.2A.sub.3B.sub.11P.sub.2O.sub.23 (A=K, Rb, Cs, NH.sub.4)+33H.sub.2O as follows: [0066] a. Reagents were weighed according to stoichiometric proportion, and loaded into a 21 mL Teflon-lined autoclave, further added 3 mL deionized water to obtain the mixed liquid. [0067] b. The mixture was loaded into Teflon-lined autoclave and subsequently sealed; [0068] c. The autoclave was heated to 120 C. at a rate of 20 C./h, held at this temperature for 5 days, and then cooled to room temperature at a rate of 4 C./h; [0069] d. Open the autoclave and filter the solution containing crystals to obtain a transparent alkali metal borophosphates compounds.

Embodiment 5

[0070] A.sub.3B.sub.11P.sub.2O.sub.23 (A=K, Rb, Cs, NH.sub.4) polycrystalline powder was prepared according to a reaction formula: 3AF (A=K, Rb, Cs, NH.sub.4)+11H.sub.3BO.sub.3+2NH.sub.4H.sub.2PO.sub.4.fwdarw.A.sub.3B.sub.11P.sub.2O.sub.23 (A=K, Rb, Cs, NH.sub.4)+18 H.sub.2O+3HF+2NH.sub.3 as follows: [0071] a. Reagents were weighed according to stoichiometric proportion, and loaded into a 150 mL Teflon-lined autoclave, further added 50 mL deionized water to obtain the mixed liquid. [0072] b. The mixture was loaded into Teflon-lined autoclave and subsequently sealed; [0073] c. The autoclave was heated to 330 C. at a rate of 10 C./h, held at this temperature for 10 days, and then cooled to room temperature at a rate of 3 C./h; [0074] d. Open the autoclave and filter the solution containing crystals to obtain a transparent alkali metal borophosphates compounds.

Embodiment 6

[0075] A.sub.3B.sub.11P.sub.2O.sub.23 (A=K, Rb, Cs, NH.sub.4) polycrystalline powder was prepared according to a reaction formula: 3A.sub.2CO.sub.3 (A=K, Rb, Cs, NH.sub.4)+11B.sub.2O.sub.3+4NH.sub.4H.sub.2PO.sub.4.fwdarw.2A.sub.3B.sub.11P.sub.2O.sub.23 (A=K, Rb, Cs, NH.sub.4)+6H.sub.2O+3CO.sub.2+4NH.sub.3 as follows:

[0076] Reagents were weighed according to stoichiometric proportion, and then the mixture was placed in a beaker (10 mL), further add 0.1 mL deionized water into the beaker and stirred until dissolved completely. Then put the beaker on the heating table and heat it to 25 C. After 2 days, the series of alkali metal borophosphates nonlinear optical crystals are obtained. In order to further grow them, the seed crystals of the series of crystals were suspended in solution with fine platinum wires. In order to reduce the evaporation of water, the beaker is covered with a layer of polyethylene plate and pierced with dozens of millimeter sized holes. After 3 weeks, take out a centimeter size alkali metal borophosphates nonlinear optical crystals from the solution.

Embodiment 7

[0077] A.sub.3B.sub.11P.sub.2O.sub.23 (A=K, Rb, Cs, NH.sub.4) polycrystalline powder was prepared according to a reaction formula: 3A.sub.2CO.sub.3 (A=K, Rb, Cs, NH.sub.4)+11B.sub.2O.sub.3+2P.sub.2O.sub.5.fwdarw.2A.sub.3B.sub.11P.sub.2O.sub.23 (A=K, Rb, Cs, NH.sub.4)+3CO.sub.2 as follows:

[0078] Reagents were weighed according to stoichiometric proportion, and then the mixture was placed in a beaker (1000 mL), further add 400 mL deionized water into the beaker and stirred until dissolved completely. Then put the beaker on the heating table and heat it to 400 C. After 7 days, the series of alkali metal borophosphates nonlinear optical crystals are obtained. In order to further grow them, the seed crystals of the series of crystals were suspended in solution with fine platinum wires. In order to reduce the evaporation of water, the beaker is covered with a layer of polyethylene plate and pierced with dozens of millimeter sized holes. After 5 weeks, take out a centimeter size alkali metal borophosphate nonlinear optical crystal from the solution.

Embodiment 8

[0079] A.sub.3B.sub.11P.sub.2O.sub.23 (A=K, Rb, Cs, NH.sub.4) polycrystalline powder was prepared according to a reaction formula: 3AH.sub.2PO.sub.4 (A=K, Rb, Cs, NH.sub.4)+5.5B.sub.2O.sub.3.fwdarw.A.sub.3B.sub.11P.sub.2O.sub.23 (A=K, Rb, Cs, NH.sub.4)+1.5H.sub.2O+H.sub.3PO.sub.4 as follows:

[0080] Reagents were weighed according to stoichiometric proportion, preparation of A.sub.3B.sub.11P.sub.2O.sub.23 (A=K, Rb, Cs, NH.sub.4) crystal by fluxing agent method: AOH (A=K, Rb, Cs, NH.sub.4)PbO as the fluxing agent system, the said reagents are used as the solute with the molar ratio of solute:fluxing agent=4:7, the molar ratio of AOH (A=K, Rb, Cs, NH.sub.4)/PbO was selected at 1/6. Then, mixed the said reagents with fluxing agent and put into a 80 mm80 mm lidless platinum crucible which was placed in the center of a vertical, programmable temperature furnace, was heated at 350 C., held at this temperature for 60 h, and then quickly cooled to the initial crystallization temperature (330 C.).

[0081] The temperature was decreased to room temperature at a rate of 3.5 C./h to obtain the seeds.

[0082] A seed crystal of A.sub.3B.sub.11P.sub.2O.sub.23 (A=K, Rb, Cs, NH.sub.4) was attached with Pt wire to a Pt rod and then suspended on solution at 330 C. for 15 minutes. The seed crystal was kept at this temperature in solution for half an hour while rotating at a rate of 10 rpm. The temperature of the furnace was first lowered quickly to 315 C. and then lowered at a rate of 3 C./day. After the growth of crystal ended, the crystal was lifted out of liquid surface. The temperature of the crystal was then lowered to room temperature at a rate of 1 C./h. As a result, transparent A.sub.3B.sub.11P.sub.2O.sub.23 (A=K, Rb, Cs, NH.sub.4) crystal with a size of 25 mm24 mm10 mm was obtained.

Embodiment 9

[0083] A.sub.3B.sub.11P.sub.2O.sub.23 (A=K, Rb, Cs, NH.sub.4) polycrystalline powder was prepared according to a reaction formula: 3A.sub.2HPO.sub.4 (A=K, Rb, Cs)+11B.sub.2O.sub.3+0.5P.sub.2O.sub.5.fwdarw.2A.sub.3B.sub.11P.sub.2O.sub.23 (A=K, Rb, Cs, NH.sub.4)+1.5H.sub.2O as follows:

[0084] Reagents were weighed according to stoichiometric proportion, preparation of A.sub.3B.sub.11P.sub.2O.sub.23 (A=K, Rb, Cs, NH.sub.4) crystal by fluxing agent method: A.sub.2CO.sub.3 (A=K, Rb, Cs, NH.sub.4)H.sub.3BO.sub.3NH.sub.4H.sub.2PO.sub.4 as the fluxing agent system, the said reagents are used as the solute with the molar ratio of solute:fluxing agent=5:2, the molar ratio of A.sub.2CO.sub.3 (A=K, Rb, Cs, NH.sub.4 NH.sub.4)/H.sub.3BO.sub.3/NH.sub.4H.sub.2PO.sub.4 was selected at 5/16/16. Then, mixed the said reagents with fluxing agent and put into a (P 80 mm80 mm lidless platinum crucible which was placed in the center of a vertical, programmable temperature furnace, was heated at 550 C., held at this temperature for 60 h, and then quickly cooled to the initial crystallization temperature (530 C.).

[0085] The temperature was decreased to room temperature at a rate of 3.5 C./h to obtain the seeds.

[0086] A seed crystal of A.sub.3B.sub.11P.sub.2O.sub.23 (A=K, Rb, Cs, NH.sub.4) was attached with Pt wire to a Pt rod and then suspended on solution at 530 C. for 15 minutes. The seed crystal was kept at this temperature in solution for half an hour while rotating at a rate of 10 rpm. The temperature of the furnace was first lowered quickly to 515 C. and then lowered at a rate of 3 C./day. After the growth of crystal ended, the crystal was lifted out of liquid surface. The temperature of the crystal was then lowered to room temperature at a rate of 1 C./h. As a result, transparent A.sub.3B.sub.11P.sub.2O.sub.23 (A=K, Rb, Cs, NH.sub.4) crystal with a size of 25 mm24 mm10 mm was obtained.

Embodiment 10

[0087] A.sub.3B.sub.11P.sub.2O.sub.23 (A=K, Rb, Cs, NH.sub.4) polycrystalline powder was prepared according to a reaction formula: 6AOH (A=K, Rb, Cs, NH.sub.4)+11B.sub.2O.sub.3+2P.sub.2O.sub.5.fwdarw.2A.sub.3B.sub.11P.sub.2O.sub.23 (A=K, Rb, Cs, NH.sub.4)+3H.sub.2O as follows:

[0088] Reagents were weighed according to stoichiometric proportion, preparation of A.sub.3B.sub.11P.sub.2O.sub.23 (A=K, Rb, Cs, NH.sub.4) crystal by fluxing agent method: ABF.sub.4-MoO.sub.3 as the fluxing agent system, the said reagents are used as the solute with the molar ratio of solute:fluxing agent=9:3, the molar ratio of ABF.sub.4/MoO.sub.3 was selected at 4/7. Then, mixed the said reagents with fluxing agent and put into a 80 mm80 mm lidless platinum crucible which was placed in the center of a vertical, programmable temperature furnace, was heated at 450 C., held at this temperature for 60 h, and then quickly cooled to the initial crystallization temperature (400 C.).

[0089] The temperature was decreased to room temperature at a rate of 3.5 C./h to obtain the seeds.

[0090] A seed crystal of A.sub.3B.sub.11P.sub.2O.sub.23 (A=K, Rb, Cs, NH.sub.4) was attached with Pt wire to a Pt rod and then suspended on solution at 405 C. for 15 minutes. The seed crystal was kept at this temperature in solution for half an hour while rotating at a rate of 10 rpm. The temperature of the furnace was first lowered quickly to 400 C. and then lowered at a rate of 3 C./day. After the growth of crystal ended, the crystal was lifted out of liquid surface. The temperature of the crystal was then lowered to room temperature at a rate of 1 C./h. As a result, transparent A.sub.3B.sub.11P.sub.2O.sub.23 (A=K, Rb, Cs, NH.sub.4) crystal with a size of 25 mm24 mm10 mm was obtained.

Embodiment 11

[0091] A.sub.3B.sub.11P.sub.2O.sub.23 (A=K, Rb, Cs, NH.sub.4) polycrystalline powder was prepared according to a reaction formula: 12AH.sub.2PO.sub.4 (A=K, Rb, Cs, NH.sub.4)+22H.sub.3B.sub.2O.sub.3+2P.sub.2O.sub.5.fwdarw.4A.sub.3B.sub.11P.sub.2O.sub.23 (A=K, Rb, Cs, NH.sub.4)+33H.sub.2+8H.sub.3PO.sub.4 as follows: [0092] a. Reagents were weighed according to stoichiometric proportion, and loaded into a 100 mL Teflon-lined autoclave, further added 50 g H.sub.3BO.sub.3 to obtain the mixed liquid. [0093] b. The mixture was loaded into Teflon-lined autoclave and subsequently sealed; [0094] c. The autoclave was heated to 180 C. at a rate of 20 C./h, held at this temperature for 10 days, and then cooled to room temperature at a rate of 4 C./h; [0095] d. Open the autoclave and filter the solution containing crystals to obtain a transparent alkali metal borophosphates compounds.

Embodiment 12

[0096] A.sub.3B.sub.11P.sub.2O.sub.23 (A=K, Rb, Cs, NH.sub.4) polycrystalline powder was prepared according to a reaction formula: 6ACl (A=K, Rb, Cs, NH.sub.4)+11B.sub.2O.sub.3+4NH.sub.4H.sub.2PO.sub.4.fwdarw.2A.sub.3B.sub.11P.sub.2O.sub.23 (A=K, Rb, Cs, NH.sub.4)+6HCl+4NH.sub.3+3H.sub.2O as follows: [0097] a. Reagents were weighed according to stoichiometric proportion, and loaded into a 21 mL Teflon-lined autoclave, further added 0.1 g H.sub.3BO.sub.3 to obtain the mixed liquid. [0098] b. The mixture was loaded into Teflon-lined autoclave and subsequently sealed; [0099] c. The autoclave was heated to 160 C. at a rate of 10 C./h, held at this temperature for 11 days, and then cooled to room temperature at a rate of 4 C./h; [0100] d. Open the autoclave and filter the solution containing crystals to obtain a transparent alkali metal borophosphates compounds.

Embodiment 13

[0101] A.sub.3B.sub.11P.sub.2O.sub.23 (A=K, Rb, Cs, NH.sub.4) polycrystalline powder was prepared according to a reaction formula: 6ACl (A=K, Rb, Cs, NH.sub.4)+22H.sub.3BO.sub.3+2P.sub.2O.sub.5.fwdarw.2A.sub.3B.sub.11P.sub.2O.sub.23 (A=K, Rb, Cs, NH.sub.4)+6HCl+30H.sub.2O as follows:

[0102] Reagents were weighed according to stoichiometric proportion, and then the mixture was placed in a beaker (10 mL), further add 0.1 mL deionized water into the beaker and stirred until dissolved completely. Then put the beaker on the heating table and heat it to 400 C. After 7 days, the series of alkali metal borophosphates nonlinear optical crystals are obtained. In order to further grow them, the seed crystals of the series of crystals were suspended in solution with fine platinum wires. In order to reduce the evaporation of water, the beaker is covered with a layer of polyethylene plate and pierced with dozens of millimeter sized holes. After 5 weeks, take out a centimeter size alkali metal borophosphate nonlinear optical crystal from the solution.

Embodiment 14

[0103] Any K.sub.3B.sub.11P.sub.2O.sub.23, Rb.sub.3B.sub.11P.sub.2O.sub.23, Cs.sub.3B.sub.11P.sub.2O.sub.23, and (NH.sub.4).sub.3B.sub.11P.sub.2O.sub.23 nonlinear optical crystals obtained according to embodiments 1 to 13 were mounted on the position of 3 as shown in FIG. 4; a Q-switched Nd: YAG laser device was taken as a light source with an incident wavelength of 1064 nm at the room temperature came into K.sub.3B.sub.11P.sub.2O.sub.23, Rb.sub.3B.sub.11P.sub.2O.sub.23, Cs.sub.3B.sub.11P.sub.2O.sub.23, and (NH.sub.4).sub.3B.sub.11P.sub.2O.sub.23 single crystal 3 to generate frequency-doubled laser with a wavelength of 532 nm; and an outgoing beam 4 contained infrared lights with wavelengths of 1064 nm and 532 nm, and frequency-doubled laser with a wavelength of 532 nm was obtained after the light was filtered by a light filter 5.

Embodiment 15

[0104] Any K.sub.3B.sub.11P.sub.2O.sub.23, Rb.sub.3B.sub.11P.sub.2O.sub.23, Cs.sub.3B.sub.11P.sub.2O.sub.23, and (NH.sub.4).sub.3B.sub.11P.sub.2O.sub.23 nonlinear optical crystals obtained according to embodiments 1 to 13 were mounted on the position of 3 as shown in FIG. 4; a Q-switched Nd: YAG laser device was taken as a light source with an incident wavelength of 532 nm at the room temperature came into K.sub.3B.sub.11P.sub.2O.sub.23, Rb.sub.3B.sub.11P.sub.2O.sub.23, Cs.sub.3B.sub.11P.sub.2O.sub.23, and (NH.sub.4).sub.3B.sub.11P.sub.2O.sub.23 single crystal 3 to generate frequency-doubled laser with a wavelength of 266 nm; and an outgoing beam 4 contained infrared lights with wavelengths of 532 nm and 266 nm, and frequency-doubled laser with a wavelength of 266 nm was obtained after the light was filtered by a light filter 5.

Embodiment 16

[0105] Any K.sub.3B.sub.11P.sub.2O.sub.23, Rb.sub.3B.sub.11P.sub.2O.sub.23, Cs.sub.3B.sub.11P.sub.2O.sub.23, and (NH.sub.4).sub.3B.sub.11P.sub.2O.sub.23 nonlinear optical crystals obtained according to embodiments 1 to 13 were subjected to directional cutting and polishing processing to form a single crystal device. A 1064 nm Nd: YAG Q-switched laser source was used as a pump source to generate a laser output with a wavelength shorter than 266 nm.