A nonlinear optical crystal europium germanium oxysulfide and its preparation method and application

Abstract

The present invention discloses a nonlinear optical crystal europium germanium oxysulfide and its preparation method and application. The chemical formula of the nonlinear optical crystal is Eu(II)4Eu(III)2Ge3S 11 O2, with a molecular weight of 1514.33; the preparation method specifically comprises the following steps: (1) weighing the reaction raw materials according to the element molar ratio of Eu:Ge:S:O being 6:3:11:2; (2) mixing the reaction raw materials uniformly, evacuating, and sealing; (3) sintering at high temperature, and cooling to obtain. The present invention adopts a high-temperature solid-phase synthesis method to synthesize the nonlinear optical crystal europium germanium oxysulfide, which has excellent infrared nonlinear optical properties: a long infrared absorption cutoff edge, a large nonlinear optical coefficient (1.2×AgGaS2), and the ability to exist stably in air. It can be used as a new mid- and far-infrared nonlinear optical crystal in all-solid-state lasers (high-power infrared laser systems).

Description

Technical Field

[0001] The present invention relates to the technical field of frequency doubling crystals, and more particularly to a nonlinear optical crystal europium germanium oxysulfide and a preparation method and application thereof. Background Art

[0002] All-solid-state lasers, with their advantages of compact size, high beam quality, and high power, have become a key development direction in laser technology, with applications spanning key fields such as industry, medicine, national defense, and energy. Nonlinear optical crystals, the core components of all-solid-state lasers, enable frequency conversion to produce the desired laser output wavelength.

[0003] While mature nonlinear optical crystals are currently available for the ultraviolet and visible wavelengths, high-performance frequency-converting crystals are still lacking in the mid- and far-infrared (3-20μm) and deep ultraviolet (<200nm) regions. For superior infrared nonlinear optical crystals, their performance must meet the requirements of "long infrared absorption cutoff edge, large nonlinear optical coefficient, and high resistance to laser damage (wide bandgap)" while also eliminating the performance drawbacks of existing commercial crystals, such as "low laser damage threshold and two-photon absorption." The bandgap of a crystal is directly proportional to its resistance to laser damage and inversely proportional to its nonlinear optical coefficient. Therefore, improving a crystal's resistance to laser loss while maintaining a large nonlinear optical coefficient is a significant challenge in the design and synthesis of new infrared nonlinear optical crystals. Therefore, based on the key performance requirements for infrared nonlinear optical crystals, designing new crystals that balance the demands of "damage resistance and large frequency doubling" has become a pressing challenge. Solving this critical scientific challenge will also provide effective theoretical guidance for the future development of new crystals with superior performance.

[0004] Sulfur oxides are an important research system for mixed anion inorganic functional materials. There are two different anions (O 2- and S 2- ), which can be considered a hybrid compound of an oxide and a sulfide. Given the different electronegativity, ionic radius, and bonding mechanism of the two anions, oxysulfides combine the inherent performance advantages of oxides and sulfides, showing great potential in complex and diverse structural features and rich and diverse physicochemical properties. To date, hundreds of oxysulfides have been discovered, covering a wide range of applications, making them a preferred research system for many functional materials researchers.

[0005] At present, the exploration of infrared nonlinear optical crystals has also been extended to the sulfur-oxygen system. Since oxides themselves have a wide optical band gap and high resistance to laser damage, and sulfides have a large frequency doubling capability, the crystal structure of sulfur-oxygen crystals has the potential to perfectly integrate the inherent performance advantages of oxides and sulfides. At the same time, sulfur-oxygen system crystals can avoid the corrosion of quartz tubes by halide raw materials during the synthesis of sulfur-halogen crystals, further reducing the difficulty of preparing the target crystals. This can provide a new system and new ideas for the subsequent design and synthesis of infrared nonlinear optical crystals with excellent comprehensive performance.

[0006] Therefore, how to develop an infrared nonlinear optical sulfur-oxygen crystal with excellent performance is an urgent problem that needs to be solved by those skilled in the art. Summary of the Invention

[0007] In view of this, the object of the present invention is to provide a nonlinear optical crystal europium germanium oxysulfide and its preparation method and application, so as to solve the deficiencies in the prior art.

[0008] In order to achieve the above object, the present invention adopts the following technical solutions:

[0009] A nonlinear optical crystal europium germanium oxysulfide, the chemical formula is Eu(II)4Eu(III)2Ge3S 11 O2, with a molecular weight of 1514.33. Among them, Eu atoms have two valence states of +2 and +3, while the valences of Ge atoms, S atoms and O atoms are +4, -2 and -2 respectively.

[0010] Furthermore, the nonlinear optical crystal europium germanium oxysulfide is a red, transparent single crystal with a non-centrosymmetric structure, a trigonal crystal system, and a space group of R3.

[0011] Furthermore, the unit cell parameters of the above nonlinear optical crystal Europium Germanium Oxysulfide are c = 17.9568 (6), α = β = 90°, γ = 120°, Z = 9, unit cell volume

[0012] A method for preparing the above-mentioned nonlinear optical crystal europium germanium oxysulfide specifically comprises the following steps:

[0013] (1) Weigh the reaction raw materials according to the element molar ratio of Eu:Ge:S:O of 6:3:11:2;

[0014] (2) Mix all the reaction materials evenly, evacuate and seal;

[0015] (3) Sintering at high temperature and cooling to obtain nonlinear optical crystal europium germanium oxysulfide.

[0016] Furthermore, in step (1), the weighing device is a sealed container having a water content and an oxygen content of 0.01 to 0.2 ppm. Furthermore, the water content and oxygen content are both 0.01 ppm. Furthermore, the sealed container is a vacuum glove box filled with an inert gas. Furthermore, the inert gas is argon.

[0017] Furthermore, in the above step (1), the reaction raw materials are Eu (elemental europium), EuS (elemental europium sulfide), Eu2O3 (elemental europium oxide), Ge (elemental germanium), GeS2 (germanium disulfide), GeO2 (germanium dioxide) and S (elemental sulfur).

[0018] Furthermore, in the above step (2), the vacuum degree of the vacuum pump is 10 -5 ~10 -3 Pa. Furthermore, the vacuum degree of the above vacuum pumping is 10 -3 Pa.

[0019] Furthermore, in the above step (3), the high-temperature sintering procedure is as follows: first, heating to 500-700°C at a rate of 17-20°C / h, holding for 7-10 hours; then heating to 1000-1050°C at a rate of 25-40°C / h, holding for 70-110 hours. Furthermore, the high-temperature sintering procedure is as follows: first, heating to 600°C at a rate of 17°C / h, holding for 10 hours; then heating to 1020°C at a rate of 25°C / h, holding for 96 hours.

[0020] Furthermore, in the above step (3), the cooling rate is 0.2-0.3°C / h, down to room temperature. Furthermore, the above cooling rate is 0.2°C / h.

[0021] The present invention also seeks to protect the use of the above-mentioned nonlinear optical crystal europium germanium oxysulfide or the nonlinear optical crystal europium germanium oxysulfide prepared by the above-mentioned preparation method in the preparation of infrared band laser frequency conversion crystals, infrared electro-optical devices, infrared communication devices or infrared laser guidance devices.

[0022] It can be seen from the above technical solution that compared with the prior art, the beneficial effects of the present invention are as follows:

[0023] The present invention adopts a high-temperature solid-phase synthesis method to synthesize a nonlinear optical crystal europium germanium oxysulfide, which has excellent infrared nonlinear optical properties: a long infrared absorption cutoff edge, a large nonlinear optical coefficient (1.2×AgGaS2), and the ability to exist stably in the air. It can be used as a new mid- and far-infrared nonlinear optical crystal in all-solid-state lasers (high-power infrared laser systems). BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1This is the powder XRD pattern of the nonlinear optical crystal europium germanium oxysulfide in Example 1, where the purple curve is the experimental value and the black curve is the theoretical value;

[0025] Figure 2 This is a schematic diagram of the structure of the nonlinear optical crystal europium germanium oxysulfide according to Example 1;

[0026] Figure 3 This is a transmission spectrum of the nonlinear optical crystal europium germanium oxysulfide in Example 1;

[0027] Figure 4 This is the band gap diagram of the nonlinear optical crystal europium germanium oxysulfide in Example 1;

[0028] Figure 5 This is a schematic structural diagram of a nonlinear optical system when the nonlinear optical crystal europium germanium oxysulfide or commercial crystal AgGaS2 of Example 1 is used as a frequency doubling crystal, wherein: 1-laser, 2-full-condensing lens, 3-nonlinear optical crystal europium germanium oxysulfide or commercial crystal AgGaS2 powder of Example 1, 4-output light beam, 5-filter.

[0029] Figure 6 This is a graph showing the harmonic generation intensity and sample particle size of the nonlinear optical crystal europium germanium oxysulfide and the commercial crystal AgGaS2 in Example 1. DETAILED DESCRIPTION

[0030] The following is a clear and complete description of the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts are within the scope of protection of the present invention.

[0031] Example 1

[0032] Nonlinear optical crystal europium germanium oxysulfide, chemical formula is Eu(II)4Eu(III)2Ge3S 11 O2, with a molecular weight of 1514.33, is a red, transparent, non-centrosymmetric single crystal with a trigonal crystal system, a space group of R3, and unit cell parameters of c = 17.9568 (6), α = β = 90°, γ = 120°, Z = 9, unit cell volume

[0033] The method for preparing the above-mentioned nonlinear optical crystal europium germanium oxysulfide specifically comprises the following steps:

[0034] (1) In a vacuum glove box filled with argon and containing 0.01 ppm of water and oxygen, EuS, GeS2, GeO2, and S were weighed in a molar ratio of 6:2:1:1;

[0035] (2) Mix all the raw materials evenly, put them into a clean graphite crucible, and then put them into a quartz tube. -3 After vacuuming under the condition of Pa, the sealing is carried out with hydrogen-oxygen flame;

[0036] (3) Place the sealed quartz tube in a high-temperature sintering furnace, first heat it to 600°C at a rate of 17°C / h and keep it warm for 10 hours; then heat it to 1020°C at a rate of 25°C / h and keep it warm for 96 hours; finally cool it to room temperature at a rate of 0.2°C / h to obtain the nonlinear optical crystal europium germanium oxysulfide.

[0037] Example 2

[0038] Nonlinear optical crystal europium germanium oxysulfide, chemical formula is Eu(II)4Eu(III)2Ge3S 11 O2, with a molecular weight of 1514.33, is a red, transparent, non-centrosymmetric single crystal with a trigonal crystal system, a space group of R3, and unit cell parameters of c = 17.9568 (6), α = β = 90°, γ = 120°, Z = 9, unit cell volume

[0039] The method for preparing the above-mentioned nonlinear optical crystal europium germanium oxysulfide specifically comprises the following steps:

[0040] (1) In a vacuum glove box filled with argon and containing 0.05 ppm of water and oxygen, Eu, GeS2, GeO2, and S were weighed in a molar ratio of 6:2:1:7;

[0041] (2) Mix all the raw materials evenly, put them into a clean graphite crucible, and then put them into a quartz tube. -3 After vacuuming under the condition of Pa, the sealing is carried out with hydrogen-oxygen flame;

[0042] (3) Place the sealed quartz tube in a high-temperature sintering furnace, first heat it to 700°C at a rate of 20°C / h and keep it warm for 10 hours; then heat it to 1050°C at a rate of 40°C / h and keep it warm for 96 hours; finally cool it to room temperature at a rate of 0.2°C / h to obtain the nonlinear optical crystal europium germanium oxysulfide.

[0043] Example 3

[0044] Nonlinear optical crystal europium germanium oxysulfide, chemical formula is Eu(II)4Eu(III)2Ge3S 11 O2, with a molecular weight of 1514.33, is a red, transparent, non-centrosymmetric single crystal with a trigonal crystal system, a space group of R3, and unit cell parameters of c = 17.9568 (6), α = β = 90°, γ = 120°, Z = 9, unit cell volume

[0045] The method for preparing the above-mentioned nonlinear optical crystal europium germanium oxysulfide specifically comprises the following steps:

[0046] (1) In a vacuum glove box filled with argon and containing 0.1 ppm of water and oxygen, Eu, Ge, GeO2, and S were weighed in a molar ratio of 6:2:1:11.

[0047] (2) Mix all the raw materials evenly, put them into a clean graphite crucible, and then put them into a quartz tube. -3 After vacuuming under the condition of Pa, the sealing is carried out with hydrogen-oxygen flame;

[0048] (3) Place the sealed quartz tube in a high-temperature sintering furnace, first heat it to 500°C at a rate of 20°C / h and keep it warm for 9 hours; then heat it to 1020°C at a rate of 40°C / h and keep it warm for 96 hours; finally cool it to room temperature at a rate of 0.3°C / h to obtain the nonlinear optical crystal europium germanium oxysulfide.

[0049] Example 4

[0050] Nonlinear optical crystal europium germanium oxysulfide, chemical formula is Eu(II)4Eu(III)2Ge3S 11 O2, with a molecular weight of 1514.33, is a red, transparent, non-centrosymmetric single crystal with a trigonal crystal system, a space group of R3, and unit cell parameters of c = 17.9568 (6), α = β = 90°, γ = 120°, Z = 9, unit cell volume

[0051] The method for preparing the above-mentioned nonlinear optical crystal europium germanium oxysulfide specifically comprises the following steps:

[0052] (1) In a vacuum glove box filled with argon and containing 0.15 ppm of water and oxygen, Eu2O3, GeS2, Ge, and S were weighed in a molar ratio of 2 / 3:8 / 3:3:25 / 3, respectively;

[0053] (2) Mix all the raw materials evenly, put them into a clean graphite crucible, and then put them into a quartz tube. -3 After vacuuming under the condition of Pa, the sealing is carried out with hydrogen-oxygen flame;

[0054] (3) Place the sealed quartz tube in a high-temperature sintering furnace, first heat it to 700°C at a rate of 18°C / h and keep it warm for 9 hours; then heat it to 1030°C at a rate of 40°C / h and keep it warm for 96 hours; finally cool it to room temperature at a rate of 0.3°C / h to obtain the nonlinear optical crystal europium germanium oxysulfide.

[0055] Example 5

[0056] Nonlinear optical crystal europium germanium oxysulfide, chemical formula is Eu(II)4Eu(III)2Ge3S 11 O2, with a molecular weight of 1514.33, is a red, transparent, non-centrosymmetric single crystal with a trigonal crystal system, a space group of R3, and unit cell parameters of c = 17.9568 (6), α = β = 90°, γ = 120°, Z = 9, unit cell volume

[0057] The method for preparing the above-mentioned nonlinear optical crystal europium germanium oxysulfide specifically comprises the following steps:

[0058] (1) In a vacuum glove box filled with argon and containing 0.2 ppm of water and oxygen, Eu2O3, EuS, GeS2, and S were weighed in a molar ratio of 2 / 3:8 / 3:1:7 / 3, respectively;

[0059] (2) Mix all the raw materials evenly, put them into a clean graphite crucible, and then put them into a quartz tube. -3 After vacuuming under the condition of Pa, the sealing is carried out with hydrogen-oxygen flame;

[0060] (3) Place the sealed quartz tube in a high-temperature sintering furnace, first heat it to 500°C at a rate of 20°C / h and keep it warm for 9 hours; then heat it to 1020°C at a rate of 40°C / h and keep it warm for 96 hours; finally cool it to room temperature at a rate of 0.3°C / h to obtain the nonlinear optical crystal europium germanium oxysulfide.

[0061] Performance Testing

[0062] 1. Example 1 The powder XRD pattern of the nonlinear optical crystal europium germanium oxysulfide is as follows: Figure 1 shown.

[0063] Depend on Figure 1 It can be seen that the experimental test spectrum is consistent with the theoretical XRD spectrum, indicating that the synthesized sample is a pure europium germanium oxysulfide sample.

[0064] 2. The structural diagram of the nonlinear optical crystal Europium Germanium Oxysulfide of Example 1 is shown in FIG. Figure 2 shown.

[0065] Depend on Figure 2It can be seen that the compound as a whole exhibits honeycomb structural characteristics, and the Ge-based tetrahedral units are arranged in the same direction along the c-axis.

[0066] 3. The transmission spectrum of the nonlinear optical crystal Europium Germanium Oxygen Sulfide of Example 1 is shown in FIG. Figure 3 shown.

[0067] Depend on Figure 3 It can be seen that the infrared cutoff edge of the nonlinear optical crystal Europium Germanium Oxysulfide in Example 1 is ∼20 μm.

[0068] 4. Example 1 The band gap diagram of the nonlinear optical crystal Europium Germanium Oxygen Sulfide is as follows Figure 4 shown.

[0069] Depend on Figure 4 It can be seen that the band gap of the nonlinear optical crystal Europium Germanium Oxysulfide in Example 1 is 2.12 eV.

[0070] 5. If Figure 5 As shown, the nonlinear optical crystal europium germanium oxysulfide of Example 1 and the commercial crystal AgGaS2 of different particle sizes (50 to 250 μm) are placed at position 3 respectively. At room temperature, an infrared beam with a wavelength of 2090 nm is emitted by a Q-switched Ho:Tm:Cr:YAG laser 1, which is incident on the nonlinear optical crystal europium germanium oxysulfide 3 through a condenser lens 2, generating a frequency-doubled light with a wavelength of 1045 nm. The outgoing beam 4 contains infrared light with a wavelength of 2090 nm and light of 1045 nm, which is filtered out by a filter 5 to obtain a frequency-doubled light with a wavelength of 1045 nm. The frequency-doubled light intensity of the nonlinear optical crystal europium germanium oxysulfide and the commercial crystal AgGaS2 of Example 1 and the sample particle size curve is shown in FIG. Figure 6 shown.

[0071] Depend on Figure 6 It can be seen that under the irradiation of 2090nm fundamental frequency light, in the particle size range of 200-250μm, the output intensity of the nonlinear optical crystal europium germanium oxysulfide in Example 1 is 1.2 times that of the commercial infrared nonlinear optical crystal AgGaS2.

[0072] The above description of the disclosed embodiments is intended to enable one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be readily apparent to one skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention is not limited to the embodiments shown herein but is intended to conform to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A nonlinear optical crystal europium germanium oxysulfide, characterized in that: The chemical formula is Eu(II)4Eu(III)2Ge3S 11 O2, molecular weight is 1514.33, it is a red transparent non-centrosymmetric single crystal, the crystal system is trigonal, and the space group is R 3.

2. The nonlinear optical crystal europium germanium oxysulfide according to claim 1, characterized in that: The unit cell parameters are a=b=16.8314(5)Å, c=17.9568(6), α=β=90°, γ=120°, Z=9, and the unit cell volume V=4405.5(3)Å. 3 .

3. A method for preparing the nonlinear optical crystal europium germanium oxysulfide according to claim 1, characterized in that: The specific steps include: (1) Weigh the reaction raw materials according to the element molar ratio of Eu:Ge:S:O of 6:3:11:2; (2) Mix all the reaction materials evenly, evacuate and seal; (3) sintering at a high temperature and cooling to obtain the nonlinear optical crystal europium germanium oxysulfide; The high-temperature sintering procedure is as follows: first, heating to 500-700°C at a rate of 17-20°C / h, and keeping warm for 7-10 hours; then heating to 1000-1050°C at a rate of 25-40°C / h, and keeping warm for 70-110 hours.

4. The method for preparing a nonlinear optical crystal europium germanium oxysulfide according to claim 3, characterized in that: In step (1), the weighing equipment is a closed container with a water content and an oxygen content of 0.01 to 0.2 ppm.

5. The method for preparing a nonlinear optical crystal europium germanium oxysulfide according to claim 3, characterized in that: In step (1), the reaction raw materials are selected from Eu, EuS, Eu2O3, Ge, GeS2, GeO2 and S.

6. The method for preparing a nonlinear optical crystal europium germanium oxysulfide according to claim 3, characterized in that: In step (2), the vacuum degree of the vacuum pump is 10 -5 ~10 -3 Pa.

7. The method for preparing a nonlinear optical crystal europium germanium oxysulfide according to claim 3, characterized in that: In step (3), the cooling rate is 0.2-0.3°C / h, down to room temperature.

8. Use of the nonlinear optical crystal europium germanium oxysulfide according to any one of claims 1 to 2 or the nonlinear optical crystal europium germanium oxysulfide prepared by the preparation method according to any one of claims 3 to 7 in the preparation of infrared laser frequency conversion crystals, infrared electro-optical devices, infrared communication devices or infrared laser guidance devices.

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