Alkali metal molybdenum iodates and their nonlinear optical crystals, their preparation methods and applications

Abstract

This invention relates to alkali metal molybdenum iodide compounds and alkali metal molybdenum iodide nonlinear optical crystals, their preparation methods, and applications. The series of compounds and crystals all have the general chemical formula AMo₂IO₉, where A = K, Rb, and Cs, all belonging to the monoclinic crystal system, space group P2, with cell parameters α = γ = 90°, β = 85–95°, and Z = 1. The alkali metal molybdenum iodide compounds are synthesized using high-temperature solid-state reaction and hydrothermal methods, while the alkali metal molybdenum iodide crystals are grown using hydrothermal and solution methods. These materials can be used in second harmonic generators, up- and down-frequency converters, optical parametric oscillators, etc.

Description

Technical Field

[0001] This invention relates to a compound alkali metal molybdenum iodate and its nonlinear optical crystal. The general molecular formula of the compound alkali metal molybdenum iodate and its crystal is AMo2IO9, where A = K, Rb, Cs. The invention also relates to the preparation method of the crystal and the nonlinear optical device made using the crystal. Technical Background

[0002] The exploration of novel nonlinear optical crystals with high frequency doubling coefficients, high conversion efficiency, good chemical stability, wide transmission bands, and high optical damage thresholds has always been a hot topic in the field of laser frequency conversion. Currently, the main nonlinear optical materials include: β-BaB2O4 (BBO) crystal, KB3O5 (LBO) crystal, CsB3O5 (CBO) crystal, and CsKB6O... 10 (CLBO) crystals and KBe2BO3F2 (KBBF) crystals. Although the crystal growth technology for these materials has become increasingly mature, significant drawbacks remain, such as hygroscopicity, long growth cycles, and high cost. Therefore, the search for new nonlinear optical crystal materials remains a crucial and challenging task. To overcome these shortcomings, scientists worldwide continue to focus their efforts on exploring and researching various novel nonlinear optical crystals.

[0003] Metal iodates, due to the presence of iodide ions in asymmetric coordination environments and with lone pairs of electrons, can form a variety of unique structures, many of which are potential novel second-order nonlinear optical materials. They exhibit wide transmission bands, large frequency doubling coefficients, high damage thresholds, and good thermal stability. (The last sentence appears to be incomplete and possibly refers to a different topic.) 0 The incorporation of transition metals into iodates yields many novel metal iodate structures, with counter cations including alkali metals and alkaline earth metals. Due to the superposition of polarization effects between the two asymmetric structural units, many of these compounds possess non-centrosymmetric structures and exhibit excellent second-order nonlinear optical properties. Therefore, the synthesis of alkali metal-transition metal-iodates will be an effective means of designing nonlinear optical materials with large frequency doubling effects. Summary of the Invention

[0004] One of the objectives of this invention is to provide alkali metal molybdenum iodide compounds and their preparation methods.

[0005] The second objective of this invention is to provide an alkali metal molybdenum iodide nonlinear optical crystal and its preparation method.

[0006] A third objective of this invention is to provide applications for alkali metal molybdenum iodide nonlinear optical crystals.

[0007] One of the objectives of this invention is achieved as follows:

[0008] The present invention aims to provide an alkali metal molybdenum iodide compound, characterized in that the series of crystals has the molecular formula AMo₂IO₉, where A = K, Rb, Cs, lacks a center of symmetry, belongs to the monoclinic crystal system, space group P2, and has the following cell parameters. α=γ=90°, β=85-95°, Z=1. Alkali metal molybdenum iodates are prepared using a high-temperature solid-state reaction method and a hydrothermal method according to the following chemical reaction formula:

[0009] 1)A2CO3(A=K,Rb,Cs)+4MoO3+I2O5→2AMo2IO9(A=K,Rb,Cs)+CO2↑

[0010] 2)4ANO3(A=K,Rb,Cs)+8MoO3+2I2O5→4AMo2IO9(A=K,Rb,Cs)+4NO2↑+O2↑

[0011] 3)2AOH(A=K,Rb,Cs)+4MoO3+I2O5→2AMo2IO9(A=K,Rb,Cs)+H2O↑

[0012] 4)2A2SO4(A=K,Rb,Cs)+8MoO3+2I2O5→4AMo2IO9(A=K,Rb,Cs)+2SO2↑+O2↑

[0013] 5)A2CO3(A=K,Rb,Cs)+4MoO3+2HIO3→2AMo2IO9(A=K,Rb,Cs)+CO2↑+H2O↑

[0014] 6)4ANO3(A=K,Rb,Cs)+8MoO3+4H5IO6→4AMo2IO9(A=K,Rb,Cs)+10H2O↑+3O2↑+4NO2↑

[0015] 7)2A2C2O4(A=K,Rb,Cs)+8MoO3+4H5IO6→4AMo2IO9(A=K,Rb,Cs)+4CO2↑+10H2O↑+O2↑

[0016] The second objective of this invention is achieved as follows:

[0017] The present invention aims to provide a series of alkali metal molybdenum iodide nonlinear optical crystals, characterized in that the general molecular formula of this series of alkali metal molybdenum iodide nonlinear optical crystals is AMo2IO9, where A = K, Rb, Cs, belonging to the monoclinic crystal system, space group P2, and cell parameters are as follows. α = γ = 90°, β = 85-95°, Z = 1. Alkali metal molybdenum iodide nonlinear optical crystals were grown using hydrothermal and solution methods, with the following specific steps:

[0018] a. Add compounds containing A=K, Rb, Cs, molybdenum, and iodine to the polytetrafluoroethylene liner of a high-pressure reactor with a volume of 25-125 mL, then add 3-50 mL of deionized water and mix thoroughly to obtain a mixture in which the molar ratio of compounds containing A=K, Rb, Cs, molybdenum, and iodine is 1-5:5-10:1-10;

[0019] b. Tighten the lid of the polytetrafluoroethylene liner containing the mixed solution in step a, then put it into the corresponding high-pressure reactor, and tighten the reactor piston.

[0020] c. Place the high-pressure reactor from step b in a constant temperature chamber, heat it to 150-230℃, keep it at that temperature for a period of time, and then cool it to room temperature.

[0021] d. Open the high-pressure reactor and filter the solution containing the crystals to obtain a transparent alkali metal molybdenum iodide nonlinear optical crystal.

[0022] Alternatively, compounds containing A=K, Rb, and Cs, molybdenum, and iodine can be added to a 25-500 mL beaker, followed by 3-400 mL of deionized water. The solution is stirred until clear. The beaker is then placed on a heating stage and heated to 25-150 degrees Celsius. After 1-10 days, the series of alkali metal molybdenum iodide nonlinear optical crystals are obtained. To further grow them, seed crystals of this series are suspended in the solution using fine platinum wire. To reduce water evaporation, the beaker is covered with a polyethylene plate with several tens of millimeter-sized holes punched in it. After 1-5 weeks, a centimeter-sized alkali metal molybdenum iodide nonlinear optical crystal is removed from the solution.

[0023] The third objective of this invention is achieved as follows:

[0024] The aforementioned alkali metal molybdenum iodide crystals are suitable for nonlinear optical devices such as frequency multipliers, up or down frequency converters, or optical parametric oscillators. Attached Figure Description

[0025] Figure 1 This is a comparison of the X-ray diffraction pattern of the present invention and the crystal X-ray diffraction pattern obtained in Example 1.

[0026] Figure 2 This is a crystal structure diagram of the alkali metal molybdenum iodide salt of the present invention;

[0027] Figure 3The working principle diagram of the nonlinear optical device fabricated in this invention includes (1) a laser, (2) a full-focus lens, (3) an alkali metal molybdenum iodide nonlinear optical crystal, (4) a beam splitter, (5) a filter, and ω is the frequency of the refracted light. Detailed Implementation

[0028] The present invention will now be described in detail with reference to the accompanying drawings and embodiments:

[0029] Example 1:

[0030] According to the reaction formula: A2CO3(A=K,Rb,Cs)+4MoO3+I2O5→2AMo2IO9(A=K,Rb,Cs)+CO2↑, the compound AMo2IO9(A=K,Rb,Cs) is synthesized.

[0031] a. Add A2CO3 (A=K,Rb,Cs) to the polytetrafluoroethylene liner of a 25mL high-pressure reactor at a molar ratio of 1:7, then add MoO3 and I2O5, and finally add 4mL of deionized water. Mix thoroughly to obtain a mixture.

[0032] b. Tighten the polytetrafluoroethylene liner cap containing the mixture from step a, then place it into a clean and uncontaminated high-pressure reactor, and tighten the reactor piston.

[0033] c. Place the high-pressure reactor from step 5 in a constant temperature chamber, raise the temperature to 220°C at a rate of 20°C / h, maintain the temperature for 5 days, and then cool it to room temperature at a rate of 4°C / h.

[0034] d. Open the high-pressure reactor and filter the solution containing crystals to obtain the compound alkali metal molybdenum iodide. The product is a transparent crystal.

[0035] Example 2

[0036] The chemical reaction is: 4ANO3 (A=K,Rb,Cs) + 8MoO3 + 2I2O5 → 4AMo2IO9 (A=K,Rb,Cs) + 4NO2↑ + O2↑

[0037] The specific steps for preparing the alkali metal molybdenum iodate compound are as follows:

[0038] a. Add 4ANO3 (A=K,Rb,Cs) to the polytetrafluoroethylene liner of a 25mL high-pressure reactor at a molar ratio of 1:4, add MoO3 and I2O5, then add 5mL of deionized water and mix thoroughly to obtain a mixture.

[0039] b. Tighten the polytetrafluoroethylene liner cap containing the mixture from step a, then place it into a clean and uncontaminated high-pressure reactor, and tighten the reactor piston.

[0040] c. Place the high-pressure reactor from step 5 in a constant temperature chamber, raise the temperature to 180°C at a rate of 20°C / h, maintain the temperature for 5 days, and then cool it to room temperature at a rate of 3°C / h.

[0041] d. Open the high-pressure reactor and filter the solution containing crystals to obtain the compound alkali metal molybdenum iodide. The product is a transparent crystal.

[0042] Example 3

[0043] The chemical reaction is as follows: 2AOH (A=K,Rb,Cs) + 4MoO3 + I2O5 → 2AMo2IO9 (A=K,Rb,Cs) + H2O↑

[0044] The specific steps for preparing the alkali metal molybdenum iodate compound are as follows:

[0045] a. Add AOH (A=K,Rb,Cs) to the polytetrafluoroethylene liner of a 125mL high-pressure reactor at a molar ratio of 1:7, add MoO3 and I2O5, then add 45mL of deionized water and mix thoroughly to obtain a mixture.

[0046] b. Tighten the polytetrafluoroethylene liner cap containing the mixture from step a, then place it into a clean and uncontaminated high-pressure reactor, and tighten the reactor piston.

[0047] c. Place the high-pressure reactor from step 5 in a constant temperature chamber, raise the temperature to 220°C at a rate of 20°C / h, maintain the temperature for 5 days, and then cool it to room temperature at a rate of 4°C / h.

[0048] d. Open the high-pressure reactor and filter the solution containing crystals to obtain the compound alkali metal molybdenum iodide. The product is a transparent crystal.

[0049] Example 4

[0050] The chemical reaction is as follows: 2A₂SO₄(A=K,Rb,Cs) + 8MoO₃ + 2I₂O₅ → 4AMo₂IO₉(A=K,Rb,Cs) + 2SO₂↑ + O₂↑

[0051] The specific steps for preparing the alkali metal molybdenum iodate compound are as follows:

[0052] a. At a molar ratio of 3:9, first add 2A2SO4 (A=K,Rb,Cs) to the polytetrafluoroethylene liner of a 25mL high-pressure reactor, add MoO3 and I2O5, and then add 4mL of deionized water to mix them thoroughly to obtain a mixture.

[0053] b. Tighten the polytetrafluoroethylene liner cap containing the mixture from step a, then place it into a clean and uncontaminated high-pressure reactor, and tighten the reactor piston.

[0054] c. Place the high-pressure reactor from step 5 in a constant temperature chamber, raise the temperature to 220°C at a rate of 20°C / h, maintain the temperature for 5 days, and then cool it to room temperature at a rate of 4°C / h.

[0055] d. Open the high-pressure reactor and filter the solution containing crystals to obtain the compound alkali metal molybdenum iodide. The product is a transparent crystal.

[0056] Example 5

[0057] The chemical reaction is A2CO3 (A=K,Rb,Cs) + 4MoO3 + 2HIO3 → 2AMo2IO9 (A=K,Rb,Cs) + CO2↑ + H2O↑

[0058] The specific steps for preparing the alkali metal molybdenum iodate compound are as follows:

[0059] a. At a molar ratio of 4:6, first add A2CO3 (A=K,Rb,Cs) to the polytetrafluoroethylene liner of a 25mL high-pressure reactor, add MoO3 and I2O5, then add 5mL of deionized water, and mix thoroughly to obtain a mixture.

[0060] b. Tighten the polytetrafluoroethylene liner cap containing the mixture from step a, then place it into a clean and uncontaminated high-pressure reactor, and tighten the reactor piston.

[0061] c. Place the high-pressure reactor from step 5 in a constant temperature chamber, raise the temperature to 220°C at a rate of 20°C / h, maintain the temperature for 5 days, and then cool it to room temperature at a rate of 3°C / h; d. Open the high-pressure reactor, filter the solution containing crystals, and obtain the compound alkali metal molybdenum iodide. The obtained product is a transparent crystal.

Claims

1. A compound of alkali metal molybdenum iodide, characterized in that... The compound has the general molecular formula AMo₂IO₉, where A = K, Rb, Cs, lacks a center of symmetry, belongs to the monoclinic crystal system, and has the space group [missing information]. P 2. The unit cell parameters are a = 3.50692(6) - 4.7139(12) Å, b = 6.05744 - 7.1665(19) Å, c = 6.5950(10) - 7.7201(2) Å, α = γ = 90°, β = 85-95°, Z = 1, and the unit cell volume V = 142.48(5) - 252.29(10) Å. 3 Furthermore, the molar ratio of molybdenum to iodine in the compound is 2:

1.

2. The method for preparing the alkali metal molybdenum iodate compound according to claim 1, characterized in that, A series of alkali metal molybdenum iodide compounds were synthesized using high-temperature solid-state reaction or hydrothermal methods.

3. The method for preparing the alkali metal molybdenum iodate compound according to claim 2, characterized in that... The following steps are performed: A compound containing A=K,Rb,Cs, a molybdenum compound, and an iodine compound are mixed evenly, ground, and then placed in a muffle furnace. The pre-calcination temperature is 100-200℃ to remove moisture and gases from the raw materials. After cooling to room temperature, the mixture is removed, ground, and then calcined in a muffle furnace at a temperature of 210-500℃ to obtain a series of polycrystalline powders of alkali metal molybdenum iodate compounds. The molar ratio of K, Rb,Cs in the A=K,Rb,Cs compound, molybdenum in the molybdenum compound, and iodine in the iodine compound is 0.5-1:1-4:0.5-2. Alternatively, add compounds containing A=K,Rb,Cs, molybdenum, and iodine to the polytetrafluoroethylene liner of a high-pressure reactor with a volume of 25-125 mL, then add 3-50 mL of deionized water and mix thoroughly to obtain a mixture in which the molar ratio of compounds containing A=K,Rb,Cs, molybdenum, and iodine is 1-5:5-10:1-10. b. Tighten the lid of the polytetrafluoroethylene liner containing the mixed solution in step a, then put it into the corresponding high-pressure reactor, and tighten the reactor piston. c. Place the high-pressure reactor from step b in a constant temperature chamber, heat it to 150-230℃, keep it at that temperature for a period of time, and then cool it to room temperature. d. Open the high-pressure reactor and filter the solution containing crystals to obtain a transparent alkali metal molybdenum iodide compound; The A=K, Rb, Cs-containing compounds include at least one of potassium hydroxide, potassium oxide, potassium salts, rubidium hydroxide, rubidium oxide, rubidium salts, cesium hydroxide, cesium oxide, and cesium salts; potassium salts include at least one of potassium chloride, potassium bromide, potassium nitrate, potassium oxalate, potassium carbonate, potassium bicarbonate, and potassium sulfate; rubidium salts include at least one of rubidium chloride, rubidium bromide, rubidium nitrate, rubidium oxalate, rubidium carbonate, rubidium bicarbonate, and rubidium sulfate; and cesium salts include at least one of cesium chloride, cesium bromide, cesium nitrate, cesium oxalate, cesium carbonate, cesium bicarbonate, and cesium sulfate. The molybdenum-containing compound includes at least one of molybdenum oxide, molybdenum hydroxide, and molybdenum salts; the molybdenum salts include at least one of molybdenum chloride, molybdenum bromide, molybdenum nitrate, molybdenum oxalate, molybdenum carbonate, and molybdenum sulfate. The iodine-containing compound is iodine pentoxide, iodic acid, periodic acid, and iodized salts; the iodized salts include at least one of potassium iodate, rubidium iodate, cesium iodate, potassium periodate, rubidium periodate, and cesium periodate.

4. An alkali metal molybdenum iodide nonlinear optical crystal, characterized in that... The general molecular formula of this crystal is AMo₂IO₉, where A = K, Rb, Cs. It does not have a center of symmetry, belongs to the monoclinic crystal system, and has the space group [missing information]. P 2. The unit cell parameters are a = 3.50692(6) - 4.7139(12) Å, b = 6.05744 - 7.1665(19) Å, c = 6.5950(10) - 7.7201(2) Å, α = γ = 90°, β = 85-95°, Z = 1, and the unit cell volume V = 142.48(5) - 252.29(10) Å. 3 Furthermore, the molar ratio of molybdenum to iodine in the compound is 2:

1.

5. The method for preparing the alkali metal molybdenum iodide nonlinear optical crystal according to claim 4, characterized in that, A series of alkali metal molybdenum iodate nonlinear optical crystals were grown using hydrothermal or solution methods.

6. The method according to claim 5, characterized in that, The specific steps are as follows: a. Add compounds containing A=K,Rb,Cs, molybdenum, and iodine to the polytetrafluoroethylene liner of a high-pressure reactor with a volume of 25-125 mL, then add 3-50 mL of deionized water and mix thoroughly to obtain a mixture in which the molar ratio of compounds containing A=K,Rb,Cs, molybdenum, and iodine is 1-5:5-10:1-10; b. Tighten the lid of the polytetrafluoroethylene liner containing the mixed solution in step a, then put it into the corresponding high-pressure reactor, and tighten the reactor piston. c. Place the high-pressure reactor from step b in a constant temperature chamber, heat it to 150-230℃, keep it at that temperature for a period of time, and then cool it to room temperature. d. Open the high-pressure reactor and filter the solution containing the crystals to obtain a transparent alkali metal molybdenum iodide nonlinear optical crystal. Alternatively, compounds containing A=K,Rb,Cs, molybdenum, and iodine can be added to a beaker with a volume of 25-500 mL, followed by 3-400 mL of deionized water. The solution is stirred until clear. The beaker is then placed on a heating platform and heated to 25-150 degrees Celsius. After 1-10 days, the alkali metal molybdenum iodide nonlinear optical crystal is obtained. To further grow it, a seed crystal is suspended in the solution using a fine platinum wire. To reduce water evaporation, a polyethylene plate is placed over the beaker and several tens of millimeter-sized holes are punched in it. After 1-5 weeks, a centimeter-sized alkali metal molybdenum iodide nonlinear optical crystal is removed from the solution.

7. The use of the alkali metal molybdenum iodide nonlinear optical crystal according to claim 4, characterized in that, This alkali metal molybdenum iodide nonlinear optical crystal is used in second harmonic generators, up or down frequency converters, optical parametric oscillators, laser frequency conversion devices, and nonlinear optical devices for laser communication.

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