Compounds Alkali Metal Borophosphates, 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), their producing method and uses thereof. A.sub.3B.sub.11P.sub.2O.sub.23 (A=K, Rb, Cs) belong to triclinic crystal system, and have a space group of P1, crystal cell parameters of a=6.284(8)-8.784(3) , b=6.338(3)-8.838(3) , c=6.463(3)-8.963(3) , =70-105, =75-106, =76-107 and Z=1 and a unit cell volume of V=257.4(3)-696.0(6) .sup.3. A.sub.3B.sub.11P.sub.2O.sub.23 (A=K, Rb, Cs) compounds were prepared by a high-temperature solid-state reaction method or a hydrothermal method, and A.sub.3B.sub.11P.sub.2O.sub.23 (A=K, Rb, Cs) NLO crystals were prepared by a high-temperature solid-state reaction method, a hydrothermal method or a solution method. These materials can be used to manufacture second harmonic generator, up-down frequency converter, optical parametric oscillator, etc.

Claims

1. The compounds alkali metal borophosphates, wherein the compounds have a chemical formula of A.sub.3B.sub.11P.sub.2O.sub.23 (A=K, Rb, Cs), which belong to triclinic crystal system, with unit-cell parameters a=6.284(8)-8.784(3) , b=6.338(3)-8.838(3) , c=6.463(3)-8.963(3) , =70-105, =75-106, =76-107, and Z=1 and unit cell volumes of V=257.4(3)-696.0(6) .sup.3.

2. The preparation method for the compounds alkali metal borophosphates according to claim 1, comprising the following steps: performing a solid-phase reaction method after mixing a potassium/rubidium/cesium-containing compound, a boron-containing compound, a phosphorus-containing compound to obtain the compounds alkali metal borophosphates, wherein the element potassium/rubidium/cesium in the potassium/rubidium/cesium-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 2.5-3.5:9-13:1-3. The potassium containing compounds include at least one of potassium hydroxide, potassium oxide and potassium salt; potassium salt includes at least one of potassium fluoride, potassium chloride, potassium bromide, potassium nitrate, potassium oxalate, potassium carbonate, potassium bicarbonate and potassium sulfate; The rubidium containing compounds include at least one of rubidium hydroxide, rubidium oxide and rubidium salt; rubidium salt includes at least one of rubidium fluoride, rubidium chloride, rubidium bromide, rubidium nitrate, rubidium oxalate, rubidium carbonate, rubidium bicarbonate and rubidium sulfate; The cesium containing compounds include at least one of cesium hydroxide, cesium oxide and cesium salt; cesium salt includes at least one of cesium fluoride, cesium chloride, cesium bromide, cesium nitrate, cesium oxalate, cesium carbonate, cesium bicarbonate and cesium sulfate; The boron containing compounds include at least one of boron oxide, boric acid and boron salt; the boron salt includes at least one of boron chloride, boron bromide, boron nitrate, boron oxalate, boron carbonate and boron sulfate; The phosphorus containing compounds include at least one of phosphorus pentoxide and phosphorus salt; the phosphorus salt includes at least one of phosphorus chloride, phosphorus bromide, phosphorus nitrate, phosphorus oxalate, phosphorus carbonate, ammonium dihydrogen phosphate, potassium dihydrogen phosphate, potassium/rubidium/cesium dihydrogen phosphate, cesium dihydrogen phosphate and phosphorus sulfate.

3. The preparation method for the compounds alkali metal borophosphates according to claim 2, wherein the compounds alkali metal borophosphates are prepared by a high-temperature solid-phase reaction method or a hydrothermal method comprising the following steps: A mixture of a potassium/rubidium/cesium-containing compound, a boron-containing compound, a phosphorus-containing compound was thoroughly ground, in which the molar ratio of element potassium/rubidium/cesium in the potassium/rubidium/cesium-containing compound, elemental boron in the boron-containing compound, and elemental phosphorus in the phosphorus-containing compound is 2.5-3.5:9-13:1-3. And the mixture was preheated to 350-1000 C., held for a period of time, with several intermediate grindings to get compound A.sub.3B.sub.11P.sub.2O.sub.23 (A=K, Rb, Cs) polycrystalline powder, and performing X-ray analysis on the obtained compounds alkali metal borophosphates polycrystalline powder, wherein the X-ray diffraction patterns are consistent with the theoretical X-ray diffraction patterns of A.sub.3B.sub.11P.sub.2O.sub.23 (A=K, Rb, Cs) analyzed by single-crystal structures. Or a. a mixture of a potassium/rubidium/cesium-containing compound, a boron-containing compound, a phosphorus-containing compound was combined with deionized water (0.1-50 mL) or boric acid 0.1-50 g, in which element potassium/rubidium/cesium in the potassium/rubidium/cesium-containing compound, elemental boron in the boron-containing compound, and elemental phosphorus in the phosphorus-containing compound are in a molar ratio of 1-5:7-16:0.5-4; b. The mixture was loaded into Teflon-lined autoclave and subsequently sealed; c. The autoclave was heated to 120-800 C., held for a period of time, and then cooled to room temperature; d. Open the autoclave and filter the solution containing crystals to obtain the transparent alkali metal borophosphates compounds.

4. The alkali metal borophosphates nonlinear optical crystals, wherein the crystals have a chemical formula of A.sub.3B.sub.11P.sub.2O.sub.23 (A=K, Rb, Cs), which belong to triclinic crystal system, has a space group of P.sub.1, with unit-cell parameters a=6.284(8)-8.784(3) , b=6.338(3)-8.838(3) , c=6.463(3)-8.963(3) , =70-105, =75-106, =76-107 and Z=1 and a unit cell volume of V=257.4(3)-696.0(6) .sup.3.

5. The preparation method for the alkali metal borophosphates A.sub.3B.sub.11P.sub.2O.sub.23(A=K, Rb, Cs) nonlinear optical crystals adopt a high-temperature solid-state reaction method, a hydrothermal method or a solution method based on the following specific operation steps: A.sub.3B.sub.11P.sub.2O.sub.23 (A=K, Rb, Cs) polycrystalline powder with the stoichiometric ratios (A: B:P=3:11:2) or a mixture of the A.sub.3B.sub.11P.sub.2O.sub.23 (A=K, Rb, Cs) polycrystalline powder with fluxing agent is heated to obtain a mixed melt. Or directly heat the mixture of the potassium/rubidium/cesium-containing compound, boron-containing compound and phosphorus-containing compound or the mixture of potassium/rubidium/cesium-containing compound, boron-containing compound and phosphorus-containing compound and fluxing agents to obtain a mixed melt. The crucible of the liquid is placed in the crystal growth furnace, 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 nonlinear optical crystals were prepared; Or a. a mixture of a potassium/rubidium/cesium-containing compound, a boron-containing compound, a phosphorus-containing compound was combined with deionized water (0.1-50 mL) or boric acid 0.1-50 g, in which element potassium/rubidium/cesium in the potassium/rubidium/cesium-containing compound, elemental boron in the boron-containing compound, and elemental phosphorus in the phosphorus-containing compound are in a molar ratio of 1-5:7-16:0.5-4; b. The mixture was loaded into Teflon-lined autoclave and subsequently sealed; c. The autoclave was heated to 120-800 C., held for a period of time, and then cooled to room temperature; d. Open the autoclave and filter the solution containing crystals to obtain the transparent alkali metal borophosphates compounds. Or a mixture of a potassium/rubidium/cesium-containing compound, a boron-containing compound, a phosphorus-containing compound, and deionized water (0.1-400 mL) was placed in a beaker and stirred until dissolved completely. Then put the beaker on the heating table and heat it to 25-400 C. After 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 nonlinear optical crystals from the solution.

6. The method according to claim 5, wherein a molar ratio of the compound A.sub.3B.sub.11P.sub.2O.sub.23 (A=K, Rb, Cs) single-phase polycrystalline powder to the fluxing agent is 1:0-20; or a molar ratio of a potassium/rubidium/cesium-containing compound, a boron-containing compound, a phosphorus-containing compound and a fluxing agent is 0.5-5:6-16:0.5-4:0-20; The fluxing agents mainly include self-service fluxing agents, such as K.sub.2CO.sub.3, KF, KOH, K.sub.2O, KCl, KBF.sub.4, Rb.sub.2CO.sub.3, RbF, RbOH, Rb.sub.2O, RbCl, RbBF.sub.4, Cs.sub.2CO.sub.3, CsF, CsOH, Cs.sub.2O, CsCl, CsBF.sub.4, H.sub.3BO.sub.3, B.sub.2O.sub.3, KH.sub.2PO.sub.4, RbH.sub.2PO.sub.4, CsH.sub.2PO.sub.4, KBO.sub.2, RbBO.sub.2, CsBO.sub.2, NH.sub.4H.sub.2PO.sub.4, P.sub.2O.sub.5, etc. and other composite fluxing agents, such as KOHH.sub.3BO.sub.3, KOHB.sub.2O.sub.3, KOHP.sub.2O.sub.5, KOHNH.sub.4H.sub.2PO.sub.4, K.sub.2CO.sub.3H.sub.3BO.sub.3, K.sub.2CO.sub.3B.sub.2O.sub.3, K.sub.2CO.sub.3P.sub.2O.sub.5, K.sub.2CO.sub.3NH.sub.4H.sub.2PO.sub.4, KFH.sub.3BO.sub.3, KFB.sub.2O.sub.3, KFP.sub.2O.sub.5, KFNH.sub.4H.sub.2PO.sub.4, KClH.sub.3BO.sub.3, KClB.sub.2O.sub.3, KClP.sub.2O.sub.5, KClNH.sub.4H.sub.2PO.sub.4, K.sub.2OPbO, K.sub.2OPbF.sub.2, KOHPbO, KOHPbF.sub.2, KFBi.sub.2O.sub.3, KFMoO.sub.3, KBF.sub.4Bi.sub.2O.sub.3, KBF.sub.4MoO.sub.3, K.sub.2CO.sub.3Li.sub.4P.sub.2O.sub.7, K.sub.2CO.sub.3KBO.sub.2, K.sub.2CO.sub.3NaF, K.sub.2CO.sub.3NaCl, K.sub.2CO.sub.3Li.sub.4P.sub.2O.sub.7NaF, K.sub.2CO.sub.3Li.sub.4P.sub.2O.sub.7NaCl, K.sub.2CO.sub.3Li.sub.4P.sub.2O.sub.7MoO.sub.3, K.sub.2CO.sub.3LiBO.sub.2MoO.sub.3, K.sub.2CO.sub.3H.sub.3BO.sub.3P.sub.2O.sub.5, K.sub.2CO.sub.3H.sub.3BO.sub.3NH.sub.4H.sub.2PO.sub.4, K.sub.2CO.sub.3H.sub.3BO.sub.3PbO, RbOHH.sub.3BO.sub.3, RbOHB.sub.2O.sub.3, RbOHP.sub.2O.sub.5, RbOHNH.sub.4H.sub.2PO.sub.4, Rb.sub.2CO.sub.3H.sub.3BO.sub.3, Rb.sub.2CO.sub.3B.sub.2O.sub.3, Rb.sub.2CO.sub.3P.sub.2O.sub.5, Rb.sub.2CO.sub.3NH.sub.4H.sub.2PO.sub.4, RbFH.sub.3BO.sub.3, RbFB.sub.2O.sub.3, RbFP.sub.2O.sub.5, RbFNH.sub.4H.sub.2PO.sub.4, RbClH.sub.3BO.sub.3, RbClB.sub.2O.sub.3, RbClP.sub.2O.sub.5, RbClNH.sub.4H.sub.2PO.sub.4, Rb.sub.2OPbO, Rb.sub.2OPbF.sub.2, RbOHPbO, RbOHPbF.sub.2, RbFBi.sub.2O.sub.3, RbFMoO.sub.3, RbBF.sub.4Bi.sub.2O.sub.3, RbBF.sub.4MoO.sub.3, Rb.sub.2CO.sub.3Li.sub.4P.sub.2O.sub.7, Rb.sub.2CO.sub.3RbBO.sub.2, Rb.sub.2CO.sub.3NaF, Rb.sub.2CO.sub.3NaCl, Rb.sub.2CO.sub.3Li.sub.4P.sub.2O.sub.7NaF, Rb.sub.2CO.sub.3Li.sub.4P.sub.2O.sub.7NaCl, Rb.sub.2CO.sub.3Li.sub.4P.sub.2O.sub.7MoO.sub.3, Rb.sub.2CO.sub.3LiBO.sub.2MoO.sub.3, Rb.sub.2CO.sub.3H.sub.3BO.sub.3P.sub.2O.sub.5, Rb.sub.2CO.sub.3H.sub.3BO.sub.3NH.sub.4H.sub.2PO.sub.4, Rb.sub.2CO.sub.3H.sub.3BO.sub.3PbO, CSOHH.sub.3BO.sub.3, CsOHB.sub.2O.sub.3, CsOHP.sub.2O.sub.5, CsOHNH.sub.4H.sub.2PO.sub.4, CS.sub.2CO.sub.3H.sub.3BO.sub.3, CS.sub.2CO.sub.3B.sub.2O.sub.3, CS.sub.2CO.sub.3P.sub.2O.sub.5, CS.sub.2CO.sub.3NH.sub.4H.sub.2PO.sub.4, CSFH.sub.3BO.sub.3, CSFB.sub.2O.sub.3, CSFP.sub.2O.sub.5, CSFNH.sub.4H.sub.2PO.sub.4, CSClH.sub.3BO.sub.3, CSClB.sub.2O.sub.3, CSClP.sub.2O.sub.5, CSClNH.sub.4H.sub.2PO.sub.4, H.sub.3BO.sub.3P.sub.2O.sub.5, H.sub.3BO.sub.3NH.sub.4H.sub.2PO.sub.4, B.sub.2O.sub.3P.sub.2O.sub.5, B.sub.2O.sub.3NH.sub.4H.sub.2PO.sub.4, Cs.sub.2OPbO, Cs.sub.2OPbF.sub.2, CsOHPbO, CsOHPbF.sub.2, CsFBi.sub.2O.sub.3, CsFMoO.sub.3, CsBF.sub.4Bi.sub.2O.sub.3, CsBF.sub.4MoO.sub.3, Cs.sub.2CO.sub.3Li.sub.4P.sub.2O.sub.7, CS.sub.2CO.sub.3CSBO.sub.2, Cs.sub.2CO.sub.3NaF, Cs.sub.2CO.sub.3NaCl, Cs.sub.2CO.sub.3Li.sub.4P.sub.2O.sub.7NaF, Cs.sub.2CO.sub.3Li.sub.4P.sub.2O.sub.7NaCl, Cs.sub.2CO.sub.3Li.sub.4P.sub.2O.sub.7MoO.sub.3, Cs.sub.2CO.sub.3LiBO.sub.2MoO.sub.3, Cs.sub.2CO.sub.3H.sub.3BO.sub.3P.sub.2O.sub.5, Cs.sub.2CO.sub.3H.sub.3BO.sub.3NH.sub.4H.sub.2PO.sub.4, Cs.sub.2CO.sub.3H.sub.3BO.sub.3PbO, etc.

7. The method according to claim 6, wherein the composite fluxing agents, the molar ratio of KOH to B.sub.2O.sub.3 in the KOHB.sub.2O.sub.3 system of the fluxing agent is 0.5-4:0.6-12; the molar ratio of KOH to P.sub.2O.sub.5 in the KOHP.sub.2O.sub.5 system is 0.5-5:6-15; the molar ratio of KOH to NH.sub.4H.sub.2PO.sub.4 in the KOHNH.sub.4H.sub.2PO.sub.4 system is 1-4:7-12; the molar ratio of K.sub.2CO.sub.3 to H.sub.3BO.sub.3 in the K.sub.2CO.sub.3H.sub.3BO.sub.3 system is 0.5-3:0.8-16; the molar ratio of K.sub.2CO.sub.3 to B.sub.2O.sub.3 in the K.sub.2CO.sub.3B.sub.2O.sub.3 system is 1-3:0.9-16; the molar ratio of K.sub.2CO.sub.3 to P.sub.2O.sub.5 in the K.sub.2CO.sub.3P.sub.2O.sub.5 system is 0.5-2:6-12; the molar ratio of K.sub.2CO.sub.3 to NH.sub.4H.sub.2PO.sub.4 in the K.sub.2CO.sub.3NH.sub.4H.sub.2PO.sub.4 system is 1-4:1.1-16; the molar ratio of KF to H.sub.3BO.sub.3 in the KFH.sub.3BO.sub.3 system is 0.5-4:8-15; the molar ratio of KF to B.sub.2O.sub.3 in the KFB.sub.2O.sub.3 system is 0.5-3:0.6-15; the molar ratio of KF to P.sub.2O.sub.5 in the KFP.sub.2O.sub.5 system is 0.5-3:0.7-10; the molar ratio of KF to NH.sub.4H.sub.2PO.sub.4 in the KFNH.sub.4H.sub.2PO.sub.4 system is 0.5-3:6-10; the molar ratio of KCl to H.sub.3BO.sub.3 in the KClH.sub.3BO.sub.3 system is 0.5-3.5:6-14; the molar ratio of KCl to B.sub.2O.sub.3 in the KClB.sub.2O.sub.3 system is 0.5-3.5:6-14; the molar ratio of KCl to P.sub.2O.sub.5 in the KClP.sub.2O.sub.5 system is 0.5-3.5:7-15; the molar ratio of KCl to NH.sub.4H.sub.2PO.sub.4 in the KClNH.sub.4H.sub.2PO.sub.4 system is 0.5-5:6-15; the molar ratio of K.sub.2O to PbO in the K.sub.2OPbO system is 0.5-5: 6-16; the molar ratio of K.sub.2O to PbF.sub.2 in the K.sub.2OPbF.sub.2 system is 0.5-5:6-16; the molar ratio of KOH to PbO in the KOHPbO system is 0.5-5:6-16; the molar ratio of the KOH to PbF.sub.2 in the KOHPbF.sub.2 system is 0.5-5:6-16; the molar ratio of the KF to Bi.sub.2O.sub.3 in the KFBi.sub.2O.sub.3 system is 0.5-5:6-16; the molar ratio of the KF to MoO.sub.3 in the KFMoO.sub.3 system is 0.5-5:6-16; the molar ratio of the KBF.sub.4 to Bi.sub.2O.sub.3 in the KBF.sub.4Bi.sub.2O.sub.3 system is 0.5-5:6-16; the molar ratio of the KBF.sub.4 to MoO.sub.3 in the KBF.sub.4MoO.sub.3 system is 0.5-5:6-16; the molar ratio of K.sub.2CO.sub.3 to Li.sub.4P.sub.2O.sub.7 in the K.sub.2CO.sub.3Li.sub.4P.sub.2O.sub.7 system is 0.5-3.5:7-15; the molar ratio of K.sub.2CO.sub.3 to KBO.sub.2 in the K.sub.2CO.sub.3KBO.sub.2 system is 0.5-5:6-15; the molar ratio of K.sub.2CO.sub.3 to NaF in the K.sub.2CO.sub.3NaF system is 0.5-3.5:7-15; the molar ratio of K.sub.2CO.sub.3 to NaCl in the K.sub.2CO.sub.3NaCl system is 0.5-5:6-15; the molar ratio of K.sub.2CO.sub.3, Li.sub.4P.sub.2O.sub.7 to NaF in the K.sub.2CO.sub.3Li.sub.4P.sub.2O.sub.7NaF system is 0.5-5:6-16:0.6-16; the molar ratio of K.sub.2CO.sub.3, Li.sub.4P.sub.2O.sub.7 to NaCl in the K.sub.2CO.sub.3Li.sub.4P.sub.2O.sub.7NaCl system is 0.5-5:6-16:6-16; the molar ratio of K.sub.2CO.sub.3, Li.sub.4P.sub.2O.sub.7 to MoO.sub.3 in the K.sub.2CO.sub.3Li.sub.4P.sub.2O.sub.7 MoO.sub.3 system is 0.5-5:6-16:6-16; the molar ratio of K.sub.2CO.sub.3, LiBO.sub.2 to MoO.sub.3 in the K.sub.2CO.sub.3 LiBO.sub.2 MoO.sub.3 system is 0.5-5:6-16:6-16; the molar ratio of K.sub.2CO.sub.3, H.sub.3BO.sub.3 to P.sub.2O.sub.5 in the K.sub.2CO.sub.3H.sub.3BO.sub.3P.sub.2O.sub.5 system is 0.5-5:6-16:6-16; the molar ratio of K.sub.2CO.sub.3, H.sub.3BO.sub.3 to NH.sub.4H.sub.2PO.sub.4 in the K.sub.2CO.sub.3H.sub.3BO.sub.3NH.sub.4H.sub.2PO.sub.4 system is 0.5-5:6-16:6-16; the molar ratio of K.sub.2CO.sub.3, H.sub.3BO.sub.3 to PbO in the K.sub.2CO.sub.3H.sub.3BO.sub.3PbO system is 0.5-5:6-16: 6-16; the molar ratio of RbOH to B.sub.2O.sub.3 in the RbOHB.sub.2O.sub.3 system is 0.5-4:6-12; the molar ratio of RbOH to P.sub.2O.sub.5 in the RbOHP.sub.2O.sub.5 system is 0.5-5:6-15; the molar ratio of RbOH to NH.sub.4H.sub.2PO.sub.4 in the RbOHNH.sub.4H.sub.2PO.sub.4 system is 1-4:7-12; the molar ratio of Rb.sub.2CO.sub.3 to H.sub.3BO.sub.3 in the Rb.sub.2CO.sub.3H.sub.3BO.sub.3 system is 0.5-3:0.8-16; the molar ratio of Rb.sub.2CO.sub.3 to B.sub.2O.sub.3 in the Rb.sub.2CO.sub.3B.sub.2O.sub.3 system is 1-3:9-16; the molar ratio of Rb.sub.2CO.sub.3 to P.sub.2O.sub.5 in the Rb.sub.2CO.sub.3P.sub.2O.sub.5 system is 0.5-2:0.6-12; the molar ratio of Rb.sub.2CO.sub.3 to NH.sub.4H.sub.2PO.sub.4 in the Rb.sub.2CO.sub.3NH.sub.4H.sub.2PO.sub.4 system is 1-4:11-16; the molar ratio of RbF to H.sub.3BO.sub.3 in the RbFH.sub.3BO.sub.3 system is 0.5-4:8-15; the molar ratio of RbF to B.sub.2O.sub.3 in the RbFB.sub.2O.sub.3 system is 0.5-3:6-15; the molar ratio of RbF to P.sub.2O.sub.5 in the RbFP.sub.2O.sub.5 system is 0.5-3:7-10; the molar ratio of RbF to NH.sub.4H.sub.2PO.sub.4 in the RbFNH.sub.4H.sub.2PO.sub.4 system is 0.5-3:6-10; the molar ratio of RbCl to H.sub.3BO.sub.3 in the RbClH.sub.3BO.sub.3 system is 0.5-3.5:6-14; the molar ratio of RbCl to B.sub.2O.sub.3 in the RbClB.sub.2O.sub.3 system is 0.5-3.5:0.6-14; the molar ratio of RbCl to P.sub.2O.sub.5 in the RbClP.sub.2O.sub.5 system is 0.5-3.5:7-15; the molar ratio of RbCl to NH.sub.4H.sub.2PO.sub.4 in the RbClNH.sub.4H.sub.2PO.sub.4 system is 0.5-5:6-15; the molar ratio of Rb.sub.20 to PbO in the Rb.sub.2OPbO system is 0.5-5: 6-16; the molar ratio of Rb.sub.20 to PbF.sub.2 in the Rb.sub.2OPbF.sub.2 system is 0.5-5:6-16; the molar ratio of RbOH to PbO in the RbOHPbO system is 0.5-5:6-16; the molar ratio of the RbOH to PbF.sub.2 in the RbOHPbF.sub.2 system is 0.5-5:6-16; the molar ratio of the RbF to Bi.sub.2O.sub.3 in the RbFBi.sub.2O.sub.3 system is 0.5-5:6-16; the molar ratio of the RbF to MoO.sub.3 in the RbFMoO.sub.3 system is 0.5-5:6-16; the molar ratio of the RbBF.sub.4 to Bi.sub.2O.sub.3 in the RbBF.sub.4Bi.sub.2O.sub.3 system is 0.5-5:6-16; the molar ratio of the RbBF.sub.4 to MoO.sub.3 in the RbBF.sub.4MoO.sub.3 system is 0.5-5:6-16; the molar ratio of Rb.sub.2CO.sub.3 to Li.sub.4P.sub.2O.sub.7 in the Rb.sub.2CO.sub.3Li.sub.4P.sub.2O.sub.7 system is 0.5-3.5:7-15; the molar ratio of Rb.sub.2CO.sub.3 to RbBO.sub.2 in the Rb.sub.2CO.sub.3RbBO.sub.2 system is 0.5-5:6-15; the molar ratio of Rb.sub.2CO.sub.3 to NaF in the Rb.sub.2CO.sub.3NaF system is 0.5-3.5:0.7-15; the molar ratio of Rb.sub.2CO.sub.3 to NaCl in the Rb.sub.2CO.sub.3NaCl system is 0.5-5:6-15; the molar ratio of Rb.sub.2CO.sub.3, Li.sub.4P.sub.2O.sub.7 to NaF in the Rb.sub.2CO.sub.3Li.sub.4P.sub.2O.sub.7NaF system is 0.5-5:6-16:6-16; the molar ratio of Rb.sub.2CO.sub.3, Li.sub.4P.sub.2O.sub.7 to NaCl in the Rb.sub.2CO.sub.3Li.sub.4P.sub.2O.sub.7NaCl system is 0.5-5:0.6-16:0.6-16; the molar ratio of Rb.sub.2CO.sub.3, Li.sub.4P.sub.2O.sub.7 to MoO.sub.3 in the Rb.sub.2CO.sub.3Li.sub.4P.sub.2O.sub.7 MoO.sub.3 system is 0.5-5:6-16:6-16; the molar ratio of Rb.sub.2CO.sub.3, LiBO.sub.2 to MoO.sub.3 in the Rb.sub.2CO.sub.3 LiBO.sub.2 MoO.sub.3 system is 0.5-5:6-16:6-16; the molar ratio of Rb.sub.2CO.sub.3, H.sub.3BO.sub.3 to P.sub.2O.sub.5 in the Rb.sub.2CO.sub.3H.sub.3BO.sub.3P.sub.2O.sub.5 system is 0.5-5:6-16:6-16; the molar ratio of Rb.sub.2CO.sub.3, H.sub.3BO.sub.3 to NH.sub.4H.sub.2PO.sub.4 in the Rb.sub.2CO.sub.3H.sub.3BO.sub.3NH.sub.4H.sub.2PO.sub.4 system is 0.5-5:6-16:6-16; the molar ratio of Rb.sub.2CO.sub.3, H.sub.3BO.sub.3 to PbO in the Rb.sub.2CO.sub.3H.sub.3B.sub.03PbO system is 0.5-5:6-16: 6-16; the molar ratio of CsOH to B.sub.2O.sub.3 in the CsOHB.sub.2O.sub.3 system is 0.5-4:6-12; the molar ratio of CsOH to P.sub.2O.sub.5 in the CsOHP.sub.2O.sub.5 system is 0.5-5:6-15; the molar ratio of CsOH to NH.sub.4H.sub.2PO.sub.4 in the CsOHNH.sub.4H.sub.2PO.sub.4 system is 1-4:7-12; the molar ratio of Cs.sub.2CO.sub.3 to H.sub.3BO.sub.3 in the Cs.sub.2CO.sub.3H.sub.3BO.sub.3 system is 0.5-3:0.8-16; the molar ratio of Cs.sub.2CO.sub.3 to B.sub.2O.sub.3 in the Cs.sub.2CO.sub.3B.sub.2O.sub.3 system is 1-3:9-16; the molar ratio of Cs.sub.2CO.sub.3 to P.sub.2O.sub.5 in the Cs.sub.2CO.sub.3P.sub.2O.sub.5 system is 0.5-2:6-12; the molar ratio of Cs.sub.2CO.sub.3 to NH.sub.4H.sub.2PO.sub.4 in the Cs.sub.2CO.sub.3NH.sub.4H.sub.2PO.sub.4 system is 1-4:1.1-16; the molar ratio of CsF to H.sub.3BO.sub.3 in the CsFH.sub.3BO.sub.3 system is 0.5-4:8-15; the molar ratio of CsF to B.sub.2O.sub.3 in the CsFB.sub.2O.sub.3 system is 0.5-3:6-15; the molar ratio of CsF to P.sub.2O.sub.5 in the CsFP.sub.2O.sub.5 system is 0.5-3:7-10; the molar ratio of CsF to NH.sub.4H.sub.2PO.sub.4 in the CsFNH.sub.4H.sub.2PO.sub.4 system is 0.5-3:6-10; the molar ratio of CsCl to H.sub.3BO.sub.3 in the CsClH.sub.3BO.sub.3 system is 0.5-3.5:0.6-14; the molar ratio of CsCl to B.sub.2O.sub.3 in the CsClB.sub.2O.sub.3 system is 0.5-3.5:6-14; the molar ratio of CsCl to P.sub.2O.sub.5 in the CsClP.sub.2O.sub.5 system is 0.5-3.5:7-15; the molar ratio of CsCl to NH.sub.4H.sub.2PO.sub.4 in the CsClNH.sub.4H.sub.2PO.sub.4 system is 0.5-5:6-15; the molar ratio of H.sub.3BO.sub.3 to P.sub.2O.sub.5 in the H.sub.3BO.sub.3P.sub.2O.sub.5 system is 0.5-5:6-16; the molar ratio of H.sub.3BO.sub.3 to NH.sub.4H.sub.2PO.sub.4 in the H.sub.3BO.sub.3NH.sub.4H.sub.2PO.sub.4 system is 0.5-5:6-16; the molar ratio of B.sub.2O.sub.3 to P.sub.2O.sub.5 in the B.sub.2O.sub.3P.sub.2O.sub.5 system is 0.5-5:0.6-16; the molar ratio of B.sub.2O.sub.3 to NH.sub.4H.sub.2PO.sub.4 in the B.sub.2O.sub.3NH.sub.4H.sub.2PO.sub.4 system is 0.5-5:6-16; the molar ratio of H.sub.3B.sub.03 to NH.sub.4H.sub.2PO.sub.4 in the H.sub.3BO.sub.3NH.sub.4H.sub.2PO.sub.4 system is 0.5-5:6-16; the molar ratio of Cs.sub.2O to PbO in the Cs.sub.2OPbO system is 0.5-5: 6-16; the molar ratio of Cs.sub.2O to PbF.sub.2 in the Cs.sub.2OPbF.sub.2 system is 0.5-5:6-16; the molar ratio of CsOH to PbO in the CsOHPbO system is 0.5-5:6-16; the molar ratio of the CsOH to PbF.sub.2 in the CsOHPbF.sub.2 system is 0.5-5:6-16; the molar ratio of the CsF to Bi.sub.2O.sub.3 in the CsFBi.sub.2O.sub.3 system is 0.5-5:6-16; the molar ratio of the CsF to MoO.sub.3 in the CsFMoO.sub.3 system is 0.5-5:6-16; the molar ratio of the CsBF.sub.4 to Bi.sub.2O.sub.3 in the CsBF.sub.4Bi.sub.2O.sub.3 system is 0.5-5:6-16; the molar ratio of the CsBF.sub.4 to MoO.sub.3 in the CsBF.sub.4MoO.sub.3 system is 0.5-5:0.6-16; the molar ratio of Cs.sub.2CO.sub.3 to Li.sub.4P.sub.2O.sub.7 in the Cs.sub.2CO.sub.3Li.sub.4P.sub.2O.sub.7 system is 0.5-3.5:7-15; the molar ratio of Cs.sub.2CO.sub.3 to CsBO.sub.2 in the Cs.sub.2CO.sub.3 CsBO.sub.2 system is 0.5-5:6-15; the molar ratio of Cs.sub.2CO.sub.3 to NaF in the Cs.sub.2CO.sub.3NaF system is 0.5-3.5:7-15; the molar ratio of Cs.sub.2CO.sub.3 to NaCl in the Cs.sub.2CO.sub.3NaCl system is 0.5-5:6-15; the molar ratio of Cs.sub.2CO.sub.3, Li.sub.4P.sub.2O.sub.7 to NaF in the Cs.sub.2CO.sub.3Li.sub.4P.sub.2O.sub.7NaF system is 0.5-5:6-16:6-16; the molar ratio of Cs.sub.2CO.sub.3, Li.sub.4P.sub.2O.sub.7 to NaCl in the Cs.sub.2CO.sub.3Li.sub.4P.sub.2O.sub.7NaCl system is 0.5-5:0.6-16:0.6-16; the molar ratio of Cs.sub.2CO.sub.3, Li.sub.4P.sub.2O.sub.7 to MoO.sub.3 in the Cs.sub.2CO.sub.3Li.sub.4P.sub.2O.sub.7 MoO.sub.3 system is 0.5-5:6-16:6-16; the molar ratio of Cs.sub.2CO.sub.3, LiBO.sub.2 to MoO.sub.3 in the Cs.sub.2CO.sub.3 LiBO.sub.2 MoO.sub.3 system is 0.5-5:0.6-16:6-16; the molar ratio of Cs.sub.2CO.sub.3, H.sub.3BO.sub.3 to P.sub.2O.sub.5 in the Cs.sub.2CO.sub.3H.sub.3BO.sub.3P.sub.2O.sub.5 system is 0.5-5:0.6-16:0.6-16; the molar ratio of Cs.sub.2CO.sub.3, H.sub.3BO.sub.3 to NH.sub.4H.sub.2PO.sub.4 in the Cs.sub.2CO.sub.3H.sub.3BO.sub.3NH.sub.4H.sub.2PO.sub.4 system is 0.5-5:6-16:6-16; the molar ratio of Cs.sub.2CO.sub.3, H.sub.3BO.sub.3 to PbO in the Cs.sub.2CO.sub.3H.sub.3BO.sub.3PbO system is 0.5-5:6-16: 6-16.

8. Use of the alkali metal borophosphates nonlinear optical crystals according to claim 4, characterized in that the alkali metal borophosphates nonlinear optical crystals are used for the second harmonic generator, the upper and lower frequency converters, the optical parametric oscillation, laser frequency converter, laser communication and other nonlinear optical devices.

Description

BRIEF DESCRIPTION OF THE FIGURES

[0036] FIG. 1 is an X-ray powder diffraction pattern of a compound A.sub.3B.sub.11P.sub.2O.sub.23 (A=K, Rb, Cs) of the present invention;

[0037] FIG. 2 is a structural diagram of a A.sub.3B.sub.11P.sub.2O.sub.23 (A=K, Rb, Cs) crystal of the present invention;

[0038] FIG. 3 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) crystal of the present invention, where 1 is a laser device, 2 is a condensing lens, 3 is a A.sub.3B.sub.11P.sub.2O.sub.23 (A=K, Rb, Cs) crystal, 4 is a beam splitting prism and 5 is a light filter.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0039] The present invention is described above through specific embodiments, but the invention is not limited to these embodiments.

Embodiment 1

[0040] A.sub.3B.sub.11P.sub.2O.sub.23 (A=K, Rb, Cs) polycrystalline powder was prepared according to a reaction formula: 3A.sub.2O (A=K, Rb, Cs)+22H.sub.3BO.sub.3+2P.sub.2O.sub.5.fwdarw.2A.sub.3B.sub.11P.sub.2O.sub.23 (A=K, Rb, Cs)+33H.sub.2O as follows:

[0041] 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 300 C. slowly and held 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 750 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 750 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) analyzed by a single-crystal structure.

[0042] Preparation of A.sub.3B.sub.11P.sub.2O.sub.23 (A=K, Rb, Cs) crystal by fluxing agent method: A.sub.2O(A=K, Rb, Cs)H.sub.3BO.sub.3 as the fluxing agent system, the compound of A.sub.3B.sub.11P.sub.2O.sub.23 (A=K, Rb, Cs) is used as the solute, the molar ratio of solute/fluxing agent was selected at 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 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.

[0043] 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) was attached with Pt wire to a Pt rod and then suspended on solution at 730 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 650 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) crystals with a size of 56 mm40 mm30 mm was obtained.

Embodiment 2

[0044] A.sub.3B.sub.11P.sub.2O.sub.23 (A=K, Rb, Cs) polycrystalline powder was prepared according to a reaction formula: 3AOH (A=K, Rb, Cs)+11H.sub.3BO.sub.3O.sub.5.fwdarw.A.sub.3B.sub.11P.sub.2O.sub.23 (A=K, Rb, Cs)+18H.sub.2O as follows:

[0045] Reagents were weighed according to stoichiometric proportion, preparation of A.sub.3B.sub.11P.sub.2O.sub.23 (A=K, Rb, Cs) crystal by fluxing agent method: AOH (A=K, Rb, Cs)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)/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 1000 C., held at this temperature for 60 h, and then quickly cooled to the initial crystallization temperature (850 C.).

[0046] The temperature was decreased to room temperature at a rate of 1.5 C./h to obtain the seeds.

[0047] A seed crystal of A.sub.3B.sub.11P.sub.2O.sub.23 (A=K, Rb, Cs) was attached with Pt wire to a Pt rod and then suspended on solution at 800 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) crystals with a size of 36 mm22 mm15 mm was obtained.

Embodiment 3

[0048] A.sub.3B.sub.11P.sub.2O.sub.23 (A=K, Rb, Cs) polycrystalline powder was prepared according to a reaction formula: 3A.sub.2CO.sub.3 (A=K, Rb, Cs)+22H.sub.3BO.sub.3+2P.sub.2O.sub.5.fwdarw.2A.sub.3B.sub.11P.sub.2O.sub.23 (A=K, Rb, Cs)+33H.sub.2O+3CO.sub.2 as follows:

[0049] The said polycrystalline A.sub.3B.sub.11P.sub.2O.sub.23 (A=K, Rb, Cs) 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.).

[0050] The temperature was decreased to room temperature at a rate of 3.5 C./h to obtain the seeds.

[0051] A seed crystal of A.sub.3B.sub.11P.sub.2O.sub.23 (A=K, Rb, Cs) 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. 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) crystals with a size of 25 mm24 mm10 mm was obtained.

Embodiment 4

[0052] A.sub.3B.sub.11P.sub.2O.sub.23 (A=K, Rb, Cs) polycrystalline powder was prepared according to a reaction formula: 3A.sub.2CO.sub.3 (A=K, Rb, Cs)+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)+33H.sub.2O+3CO.sub.2+4NH.sub.3 as follows: [0053] 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. [0054] b. The mixture was loaded into Teflon-lined autoclave and subsequently sealed; [0055] c. The autoclave was heated to 120 C. at a rate of 20 C./h, held for 5 days, and then cooled to room temperature at a rate of 4 C./h; [0056] d. Open the autoclave and filter the solution containing crystals to obtain a transparent alkali metal borophosphates compounds.

Embodiment 5

[0057] A.sub.3B.sub.11P.sub.2O.sub.23 (A=K, Rb, Cs) polycrystalline powder was prepared according to a reaction formula: 3AF (A=K, Rb, Cs)+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)+18 H.sub.2O+3HF+2NH.sub.3 as follows: [0058] 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. [0059] b. The mixture was loaded into Teflon-lined autoclave and subsequently sealed; [0060] c. The autoclave was heated to 330 C. at a rate of 10 C./h, held for 10 days, and then cooled to room temperature at a rate of 3 C./h; [0061] d. Open the autoclave and filter the solution containing crystals to obtain a transparent alkali metal borophosphates compounds.

Embodiment 6

[0062] A.sub.3B.sub.11P.sub.2O.sub.23 (A=K, Rb, Cs) polycrystalline powder was prepared according to a reaction formula: 3A.sub.2CO.sub.3 (A=K, Rb, Cs)+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)+6H.sub.2O+3CO.sub.2+4NH.sub.3 as follows:

[0063] 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

[0064] A.sub.3B.sub.11P.sub.2O.sub.23 (A=K, Rb, Cs) polycrystalline powder was prepared according to a reaction formula: 3A.sub.2CO.sub.3 (A=K, Rb, Cs)+11B.sub.2O.sub.3+2P.sub.2O.sub.5.fwdarw.2A.sub.3B.sub.11P.sub.2O.sub.23 (A=K, Rb, Cs)+3CO.sub.2 as follows:

[0065] 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

[0066] A.sub.3B.sub.11P.sub.2O.sub.23 (A=K, Rb, Cs) polycrystalline powder was prepared according to a reaction formula: 3AH.sub.2PO.sub.4 (A=K, Rb, Cs)+5.5B.sub.2O.sub.3.fwdarw.A.sub.3B.sub.11P.sub.2O.sub.23 (A=K, Rb, Cs)+1.5H.sub.2O+H.sub.3PO.sub.4 as follows:

[0067] Reagents were weighed according to stoichiometric proportion, preparation of A.sub.3B.sub.11P.sub.2O.sub.23 (A=K, Rb, Cs) crystal by fluxing agent method: AOH (A=K, Rb, Cs)PbO as the fluxing agent system, the said reagents are used as the solute with the molar ratio of solute:fluxing agent=0.5:7, the molar ratio of AOH (A=K, Rb, Cs)/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.).

[0068] The temperature was decreased to room temperature at a rate of 3.5 C./h to obtain the seeds.

[0069] A seed crystal of A.sub.3B.sub.11P.sub.2O.sub.23 (A=K, Rb, Cs) 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) crystals with a size of 25 mm24 mm10 mm was obtained.

Embodiment 9

[0070] A.sub.3B.sub.11P.sub.2O.sub.23 (A=K, Rb, Cs) 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)+1.5H.sub.2O as follows:

[0071] Reagents were weighed according to stoichiometric proportion, preparation of A.sub.3B.sub.11P.sub.2O.sub.23 (A=K, Rb, Cs) crystal by fluxing agent method: A.sub.2CO.sub.3(A=K, Rb, Cs)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)/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 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.).

[0072] The temperature was decreased to room temperature at a rate of 3.5 C./h to obtain the seeds.

[0073] A seed crystal of A.sub.3B.sub.11P.sub.2O.sub.23 (A=K, Rb, Cs) 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) crystals with a size of 25 mm24 mm10 mm was obtained.

Embodiment 10

[0074] A.sub.3B.sub.11P.sub.2O.sub.23 (A=K, Rb, Cs) polycrystalline powder was prepared according to a reaction formula: 6AOH (A=K, Rb, Cs)+11B.sub.2O.sub.3+2P.sub.2O.sub.5.fwdarw.2A.sub.3Bi.sub.1P.sub.2O.sub.23 (A=K, Rb, Cs)+3H.sub.2O as follows:

[0075] Reagents were weighed according to stoichiometric proportion, preparation of A.sub.3B.sub.11P.sub.2O.sub.23 (A=K, Rb, Cs) 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 350 C., held at this temperature for 60 h, and then quickly cooled to the initial crystallization temperature (330 C.).

[0076] The temperature was decreased to room temperature at a rate of 3.5 C./h to obtain the seeds.

[0077] A seed crystal of A.sub.3B.sub.11P.sub.2O.sub.23 (A=K, Rb, Cs) 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) crystals with a size of 25 mm24 mm10 mm was obtained.

Embodiment 11

[0078] A.sub.3B.sub.11P.sub.2O.sub.23 (A=K, Rb, Cs) polycrystalline powder was prepared according to a reaction formula: 12AH.sub.2PO.sub.4 (A=K, Rb, Cs)+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)+33H.sub.2+8H.sub.3PO.sub.4 as follows: [0079] 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. [0080] b. The mixture was loaded into Teflon-lined autoclave and subsequently sealed; [0081] c. The autoclave was heated to 180 C. at a rate of 20 C./h, held for 10 days, and then cooled to room temperature at a rate of 4 C./h; [0082] d. Open the autoclave and filter the solution containing crystals to obtain a transparent alkali metal borophosphates compounds.

Embodiment 12

[0083] A.sub.3B.sub.11P.sub.2O.sub.23 (A=K, Rb, Cs) polycrystalline powder was prepared according to a reaction formula: 6ACl (A=K, Rb, Cs)+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)+6HCl+4NH.sub.3+3H.sub.2O as follows: [0084] 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. [0085] b. The mixture was loaded into Teflon-lined autoclave and subsequently sealed; [0086] c. The autoclave was heated to 160 C. at a rate of 10 C./h, held for 11 days, and then cooled to room temperature at a rate of 4 C./h; [0087] d. Open the autoclave and filter the solution containing crystals to obtain a transparent alkali metal borophosphates compounds.

Embodiment 13

[0088] A.sub.3B.sub.11P.sub.2O.sub.23 (A=K, Rb, Cs) polycrystalline powder was prepared according to a reaction formula: 6ACl (A=K, Rb, Cs)+22H.sub.3BO.sub.3+2P.sub.2O.sub.5.fwdarw.2A.sub.3B.sub.11P.sub.2O.sub.23 (A=K, Rb, Cs)+6HCl+30H.sub.2O as follows:

[0089] 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

[0090] Any alkali metal borophosphates nonlinear optical crystals obtained according to embodiments 1 to 13 was mounted on the position of 3 as shown in FIG. 3; a Q-switched Nd: YAG laser device was taken as a light source with an incident wavelength of 1064 nm at the room temperature. An infrared light beam 2 with a wavelength of 1064 nm emitted by the Q-switched Nd: YAG laser device 1 came into A.sub.3B.sub.11P.sub.2O.sub.23 (A=K, Rb, Cs) single crystal 3 to generate frequency-doubled laser with a wavelength of 532 nm; and an outgoing beam 4 contained infrared light with a wavelength of 1064 nm and light with a wavelength of 532 nm, and frequency-doubled laser with a wavelength of 532 nm was obtained after the light was filtered by a light filter 5.