Nonlinear optical crystal europium germanium sulfur oxide and preparation method and application thereof

Abstract

The invention discloses a nonlinear optical crystal europium germanium sulfur oxide and a preparation method and application thereof. The chemical formula of the nonlinear optical crystal is Eu (II) 4Eu (III) 2Ge3S11O2, and the molecular weight of the nonlinear optical crystal is 1514.33. The preparation method specifically comprises the following steps: (1) weighing reaction raw materials according to the element molar ratio of Eu: Ge: S: O of 6: 3: 11: 2; (2) uniformly mixing the reaction raw materials, vacuumizing and sealing; and (3) sintering at high temperature, and cooling. The nonlinear optical crystal europium germanium sulfur oxide is synthesized by adopting a high-temperature solid-phase synthesis method and has the advantages of excellent infrared nonlinear optical performance, relatively long infrared absorption cut-off edge, large nonlinear optical coefficient (1.2 * AgGaS2), stable existence in air and the like; the crystal can be applied to an all-solid-state laser (a high-power infrared laser system) as a novel middle and far infrared nonlinear optical crystal.

Description

Technical Field

[0001] The 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 have the advantages of small size, high beam quality and high power, and have become an important direction for the development of laser technology. Their applications cover important fields such as industry, medicine, national defense and energy. As the core component of all-solid-state lasers, nonlinear optical crystals can obtain the required laser output band through frequency conversion technology.

[0003] At present, there are mature nonlinear optical crystals in the ultraviolet and visible light bands, but there is still a lack of frequency conversion crystals with excellent performance in the mid-to-far infrared band (3-20μm) and deep ultraviolet region (<200nm). For excellent infrared nonlinear optical crystals, their performance is required to meet the requirements of "long infrared absorption cutoff edge, large nonlinear optical coefficient, high resistance to laser damage (wide band gap)", and at the same time eliminate the performance defects of existing commercial crystals such as "low laser damage threshold and two-photon absorption". Among them, the band gap of the crystal is proportional to the resistance to laser damage and inversely proportional to the nonlinear optical coefficient of the crystal. Therefore, it is a huge challenge to improve the crystal's resistance to laser loss while maintaining a large nonlinear optical coefficient for the design and synthesis of new infrared nonlinear optical crystals. Therefore, based on the requirements of infrared nonlinear optical crystals for key performance, designing new crystals to meet the balance requirements of "damage resistance and large frequency doubling" performance has become one of the problems that need to be solved urgently. At the same time, the solution of this key scientific problem can also provide effective theoretical guidance for the future research and development of new crystals with excellent performance.

[0004] Sulfur oxides are an important type of mixed anion inorganic functional materials. There are two different anions (O 2- and S 2- ), which can be regarded as a hybrid compound of oxide and sulfide. Considering the different electronegativity, ionic radius and bonding mode of the two anions, oxysulfide can combine the intrinsic performance advantages of oxides and sulfides, showing great potential in complex and diverse structural characteristics and rich and diverse physical and chemical properties. So far, hundreds of oxysulfide compounds have been discovered, covering a wide range of application fields, and are the preferred research system for many functional material 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, the sulfur-oxygen system crystals can avoid the corrosion of quartz tubes by halide raw materials during the synthesis of sulfur-halide 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 technicians in this field need to solve. 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 a preparation method and application thereof to solve the deficiencies in the prior art.

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

[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, and 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 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 the nonlinear optical crystal europium germanium oxysulfide.

[0016] Furthermore, in the above step (1), the weighed equipment is a sealed container with a water content and an oxygen content of 0.01 to 0.2 ppm. Furthermore, the water content and the 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 procedure of high temperature sintering is: firstly heating to 500-700°C at a rate of 17-20°C / h, and keeping the temperature for 7-10h; then heating to 1000-1050°C at a rate of 25-40°C / h, and keeping the temperature for 70-110h. Furthermore, the procedure of high temperature sintering is: firstly heating to 600°C at a rate of 17°C / h, and keeping the temperature for 10h; then heating to 1020°C at a rate of 25°C / h, and keeping the temperature for 96h.

[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 requests to protect the use of the above nonlinear optical crystal europium germanium oxysulfide or the nonlinear optical crystal europium germanium oxysulfide prepared by the above 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 can exist stably in the air, etc. 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 spectrum of the nonlinear optical crystal europium germanium oxysulfide in Example 1, wherein 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 of Example 1;

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

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

[0028] Figure 5 This is a schematic diagram of the structure 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 focusing 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 frequency doubling intensity and sample particle size of the nonlinear optical crystal europium germanium oxysulfide and the commercial crystal AgGaS2 of Example 1. DETAILED DESCRIPTION

[0030] The technical solutions in the embodiments of the present invention are described clearly and completely below. 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 creative work 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, molecular weight is 1514.33, it is a red transparent non-centrosymmetric single crystal, the crystal system is trigonal, the space group is R3, and the unit cell parameters are c = 17.9568 (6), α = β = 90°, γ = 120°, Z = 9, unit cell volume

[0033] The method for preparing the above 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 reaction materials evenly, put them into a clean graphite crucible, and then put them into a quartz tube. -3 After vacuuming under the condition of 1.5 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 at that temperature for 10 hours; then heat it to 1020°C at a rate of 25°C / h and keep it at that temperature 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, molecular weight is 1514.33, it is a red transparent non-centrosymmetric single crystal, the crystal system is trigonal, the space group is R3, and the unit cell parameters are c = 17.9568 (6), α = β = 90°, γ = 120°, Z = 9, unit cell volume

[0039] The method for preparing the above 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 reaction materials evenly, put them into a clean graphite crucible, and then put them into a quartz tube. -3 After vacuuming under the condition of 1.5 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 at that temperature for 10 hours; then heat it to 1050°C at a rate of 40°C / h and keep it at that temperature 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, molecular weight is 1514.33, it is a red transparent non-centrosymmetric single crystal, the crystal system is trigonal, the space group is R3, and the unit cell parameters are c = 17.9568 (6), α = β = 90°, γ = 120°, Z = 9, unit cell volume

[0045] The method for preparing the above 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 reaction materials evenly, put them into a clean graphite crucible, and then put them into a quartz tube. -3 After vacuuming under the condition of 1.5 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 at that temperature for 9 hours; then heat it to 1020°C at a rate of 40°C / h and keep it at that temperature 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, molecular weight is 1514.33, it is a red transparent non-centrosymmetric single crystal, the crystal system is trigonal, the space group is R3, and the unit cell parameters are c = 17.9568 (6), α = β = 90°, γ = 120°, Z = 9, unit cell volume

[0051] The method for preparing the above 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 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 reaction materials evenly, put them into a clean graphite crucible, and then put them into a quartz tube. -3 After vacuuming under the condition of 1.5 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 at that temperature for 9 hours; then heat it to 1030°C at a rate of 40°C / h and keep it at that temperature 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, molecular weight is 1514.33, it is a red transparent non-centrosymmetric single crystal, the crystal system is trigonal, the space group is R3, and the unit cell parameters are c = 17.9568 (6), α = β = 90°, γ = 120°, Z = 9, unit cell volume

[0057] The method for preparing the above 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 reaction materials evenly, put them into a clean graphite crucible, and then put them into a quartz tube. -3 After vacuuming under the condition of 1.5 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 at that temperature for 9 hours; then heat it to 1020°C at a rate of 40°C / h and keep it at that temperature 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 spectrum 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 sample of europium germanium oxysulfide.

[0064] 2. Example 1 The schematic diagram of the structure of the nonlinear optical crystal europium germanium oxysulfide is as follows Figure 2 shown.

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

[0066] 3. Example 1 The transmission spectrum of the nonlinear optical crystal europium germanium oxysulfide is shown in 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 oxysulfide 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 and commercial crystal AgGaS2 of Example 1 with different particle sizes (50 to 250 μm) are placed at position 3 respectively. At room temperature, an infrared light beam with a wavelength of 2090 nm is emitted by a Q-switched Ho:Tm:Cr:YAG laser 1, which is injected into the nonlinear optical crystal europium germanium oxysulfide 3 through a fully focusing lens 2 to generate a doubled frequency light with a wavelength of 1045 nm. The output light 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 doubled frequency light with a wavelength of 1045 nm. The doubled frequency intensity of the nonlinear optical crystal europium germanium oxysulfide and 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 range of particle size of 200-250μm, the output intensity of the nonlinear optical crystal europium germanium oxysulfide of Example 1 is 1.2 times that of the commercial infrared nonlinear optical crystal AgGaS2.

[0072] The above description of the disclosed embodiments enables one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be 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 will not be limited to the embodiments shown herein, but rather 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.

2. The nonlinear optical crystal europium germanium oxysulfide according to claim 1, characterized in that: It is a red, transparent, non-centrosymmetric single crystal with a trigonal crystal system and a space group of R3.

3. The nonlinear optical crystal europium germanium oxysulfide according to claim 1, characterized in that: The unit cell parameters are c = 17.9568 (6), α = β = 90°, γ = 120°, Z = 9, unit cell volume 4. A method for preparing the nonlinear optical crystal europium germanium oxysulfide as claimed in 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) high temperature sintering and cooling to obtain the nonlinear optical crystal europium germanium oxysulfide.

5. The method for preparing a nonlinear optical crystal europium germanium oxysulfide according to claim 4, 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.

6. The method for preparing a nonlinear optical crystal europium germanium oxysulfide according to claim 4, characterized in that: In step (1), the reaction raw materials are Eu, EuS, Eu2O3, Ge, GeS2, GeO2 and S respectively.

7. The method for preparing the nonlinear optical crystal europium germanium oxysulfide according to claim 4, characterized in that: In step (2), the vacuum degree of the vacuum pumping is 10 -5 ~10 -3 Pa.

8. The method for preparing a nonlinear optical crystal europium germanium oxysulfide according to claim 4, characterized in that: In step (3), the high temperature sintering procedure is: firstly, heating to 500-700°C at a rate of 17-20°C / h, and keeping warm for 7-10h; then heating to 1000-1050°C at a rate of 25-40°C / h, and keeping warm for 70-110h.

9. The method for preparing the nonlinear optical crystal europium germanium oxysulfide according to claim 4, characterized in that: In step (3), the cooling rate is 0.2-0.3°C / h, down to room temperature.

10. Use of the nonlinear optical crystal europium germanium oxysulfide as described in any one of claims 1 to 3 or the nonlinear optical crystal europium germanium oxysulfide prepared by the preparation method as described in any one of claims 4 to 9 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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