Lanthanum ion doped boric acid oxygen calcium yttrium nonlinear optical crystal material as well as preparation method and application thereof

Abstract

The invention discloses a lanthanum ion doped oxygen calcium yttrium borate nonlinear optical crystal material and a preparation method thereof, the lanthanum ion doped oxygen calcium yttrium borate nonlinear optical crystal material belongs to a monoclinic system, the space group is Cm, the chemical formula is La0.1: Y0. 9Ca4O (BO3) 3, the frequency multiplication coefficient is 2 * KDP, the ultraviolet cut-off edge is less than 200 nm, and no absorption peak with the intensity greater than or equal to 0.2 cm <-1 > exists in the range of 200-2500 nm. Therefore, the lanthanum ion doped yttrium calcium oxide borate crystal can be used as a nonlinear optical material with a wide application prospect in the field of optical parameter chirped pulse amplification.

Description

Technical Field

[0001] This invention belongs to the field of crystal growth and application technology, specifically relating to a lanthanum ion-doped yttrium oxyborate nonlinear optical crystal material, its preparation method, and its application in the field of nonlinear optics. Background Technology

[0002] In the 1980s, chirped pulse amplification (CPA) technology was proposed. As shown in the graph, CPA technology significantly improved laser focusing intensity, reaching the petawatt (10¹⁵ W) level. However, CPA technology suffers from limitations such as gain bandwidth. To overcome these shortcomings, optical parametric chirped pulse amplification (OPCPA) technology gradually developed, capable of increasing laser focusing intensity to even higher levels. Based on the principle of optical parametric amplification, OPCPA utilizes nonlinear optical crystals to amplify signal light, offering advantages such as wide bandwidth, high gain, and low noise. It can achieve efficient pulse amplification over a wider wavelength range and has been widely applied in multi-cycle pulse amplification and high-order harmonic generation.

[0003] Rare earth calcium borate oxychloride (RCa4O(BO3)3, where R is a rare earth element) is a class of crystal materials with non-centrosymmetric structures. Due to its excellent physicochemical properties, uniform melting, easy orientation, easy large-size growth, and wide transparency in the ultraviolet-visible region, it has attracted much attention in the fields of frequency conversion, optical parametric amplification, and laser gain media.

[0004] Among a series of rare-earth calcium oxyborate salt crystals, yttrium oxyborate (YCa4O(BO3)3, YCOB) crystals have become an important research direction due to their stable physicochemical properties and lack of absorption in the ultraviolet-visible-infrared regions. However, their nonlinear optical properties can be further improved.

[0005] In addition, YCOB crystals are usually grown by the Czochralski method, but this method has the problem of high cost in large-scale production.

[0006] Therefore, finding a nonlinear optical crystal with high physicochemical stability, good nonlinear optical properties, and low preparation cost is an urgent problem to be solved. Summary of the Invention

[0007] This invention addresses existing technologies by providing a lanthanum ion-doped yttrium oxyborate nonlinear optical crystal material, its preparation method, and its application in the field of high-temperature piezoelectricity.

[0008] This invention provides a lanthanum ion-doped yttrium oxyborate nonlinear optical crystal material, characterized in that the lanthanum ion-doped yttrium oxyborate nonlinear optical crystal belongs to the monoclinic crystal system, point group m, space group Cm, and has the chemical formula La.0.1 :Y 0.9 Ca4O(BO3)3 has unit cell parameters of a = 8.0737 ~ 8.183 Å, b = 16.0088 ~ 16.11 Å, c = 3.5283 ~ 3.623 Å, α = γ = 90°, and β = 101.166° ~ 101.36°.

[0009] Optionally, the crystal material has a frequency doubling factor of 2.1 × KDP, an ultraviolet cutoff edge of less than 200 nm, and no intensity greater than or equal to 0.2 cm in the 200~3000 nm range. -1 The absorption peak.

[0010] A second aspect of the present invention provides a method for preparing a lanthanum ion-doped yttrium oxyborate nonlinear optical crystal material as described in any one of the first aspects above, comprising: Step 1: Prepare lanthanum ion-doped calcium oxy borate polycrystalline material; Step 2: Place the yttrium oxyborate seed crystal at the bottom of the crucible, fill the top of the seed crystal with the polycrystalline material, and seal the crucible; Step 3: Place the crucible in the crystal growth furnace, raise the furnace temperature to melt both the polycrystalline material and the top of the seed crystal, complete the inoculation, and obtain the inoculated material; Step 4: Control the temperature gradient in the crystal growth furnace to decrease, so that the inoculated material crystallizes, is kept warm, and cooled to obtain lanthanum ion-doped yttrium oxyborate nonlinear optical crystal material.

[0011] Optionally, step 1 includes: Weigh out the raw materials CaCO3 or CaO, H3BO3 or B2O3, La2O3 and Y2O3 according to the stoichiometric ratio, and then add 1% to 10% of H3BO3 or B2O3 in an additional molar ratio, mix them evenly to obtain the mixture. The mixture is pressed into blocks and sintered and cooled at 1000℃~1100℃ to obtain the first sintered product. The first sintering product is crushed, ground, and pressed into blocks, and then sintered and cooled at 1200℃~1300℃ to obtain the lanthanum ion-doped calcium oxy borate polycrystalline material.

[0012] Optionally, the first sintering time is 12 to 20 hours, and the second sintering time is 24 to 40 hours.

[0013] Optionally, step 3 includes: The crucible is placed in a crystal growth furnace, and the part of the crucible containing the polycrystalline material is placed in the high-temperature zone of the crystal growth furnace. The temperature of the high-temperature zone is raised to the first melting temperature to melt the polycrystalline material and generate a polycrystalline molten liquid. The portion of the crucible placed on top of the seed crystal is placed in the temperature gradient zone of the crystal growth furnace, and the temperature of the temperature gradient zone is raised to the second melting temperature to melt the top of the seed crystal. The temperature is then maintained to complete the inoculation and obtain the inoculated material.

[0014] Optionally, The step of raising the temperature of the high-temperature zone to the first melting temperature to melt the polycrystalline material and generate a polycrystalline melt includes: raising the temperature of the high-temperature zone to 1480°C~1490°C within 10 hours, bringing the polycrystalline material to a fully molten state and overheating it by 50°C~100°C, and holding it at that temperature for 24 hours~48 hours to melt the polycrystalline material and obtain a polycrystalline melt. The step of raising the temperature of the temperature gradient zone to the second melting temperature to melt the top of the seed crystal, holding the temperature, and completing the inoculation to obtain the inoculated material includes: raising the temperature of the temperature gradient zone to 1410℃ ~ 1420℃ to melt the top of the seed crystal, holding the temperature for 2 hours ~ 3 hours, completing the inoculation, and obtaining the inoculated material.

[0015] Optionally, step 4 includes: The crucible is placed on the lowering device of the crystal growth furnace, and the lowering device is controlled to descend in the temperature gradient zone of the crystal growth furnace. After the inoculated material in the molten state in the crucible crystallizes, the descent is stopped, the temperature is maintained, and the material is cooled to obtain the lanthanum ion-doped calcium oxy borate polycrystalline material.

[0016] Optionally, along the direction of crucible descent, the temperature in the temperature gradient zone decreases at a gradient of 30℃ / cm to 50℃ / cm, and the crucible descent rate is 6mm / day to 10mm / day. The heat preservation conditions are: constant temperature at 1200℃~1300℃ for 1.0 hour~2.0 hours; The cooling conditions are as follows: gradually cooling to room temperature at a rate of 30°C / hour to 50°C / hour.

[0017] Optionally, the chemical formula of the yttrium oxyborate seed crystal is YCa4O(BO3)3 single crystal.

[0018] Optionally, the crucible may be Ф9 × Φ50 × 300 mm in size.

[0019] The third aspect of this invention provides an application of a lanthanum ion-doped calcium borate yttrium nonlinear optical crystal material, characterized in that the lanthanum ion-doped calcium borate yttrium nonlinear optical crystal material is the lanthanum ion-doped calcium borate yttrium nonlinear optical crystal material according to any one of claims 1 to 2 or the lanthanum ion-doped calcium borate yttrium nonlinear optical crystal material according to any one of claims 3 to 9, and the lanthanum ion-doped calcium borate yttrium nonlinear optical crystal material is used in the preparation of nonlinear optical materials and OPCPA technology.

[0020] Compared with the prior art, the features of the present invention are as follows: 1. The method for preparing lanthanum ion-doped yttrium oxyborate nonlinear optical crystals of the present invention is the crucible lowering method. This method has the following characteristics: (1) It can realize crystal growth in non-growth habit directions, flexibly meeting different application needs; (2) It uses a closed crucible, which effectively prevents external impurities from contaminating the crystal and the volatilization of melt components, ensuring crystal purity and chemical consistency; (3) It has better control over the growth rate, but the growth time is longer; (4) It is easy to control the crystal structure and morphology; (5) The growth process is simple; (6) It is not easy to generate bubbles inside the crystal; (7) The cost is low; (8) It can control the simultaneous growth of multiple crystals; (9) The axial temperature gradient is smaller than that of the Czochralski method, which is beneficial to overcome the crystal cracking problem.

[0021] 2. Due to La 3+ With Y 3+ Elements belonging to the same group and having similar chemical structures, therefore, in crystal structures, Y... 3+ The location is easily affected by La 3+ The substitution results in the formation of lanthanum ion-doped calcium borate yttrium single crystals (hereinafter referred to as La:YCOB). Simultaneously, due to the differences in their electronic layers and radii, La... 3+ Once it enters the crystal lattice, it causes changes in the crystal's lattice parameters. These changes further affect the nonlinear optical properties of the yttrium oxyborate crystal, giving it unique advantages and potential applications in nonlinear optics.

[0022] Tests show that, compared to undoped yttrium oxyborate (YCOB) crystals, lanthanum ion-doped yttrium oxyborate (La:YCOB) crystals exhibit a blue-shifted ultraviolet cutoff edge to below 200 nm, while also possessing a larger doubling coefficient (2.1 × KDP). This indicates that La:YCOB crystals have unique advantages and potential application prospects in nonlinear optics. Attached Figure Description

[0023] Figure 1 This is a physical image of the lanthanum ion-doped yttrium oxyborate nonlinear optical crystal prepared in Example 1 of this invention.

[0024] Figure 2 This is the XRD pattern of the lanthanum ion-doped yttrium borate oxygen-calcium nonlinear optical crystal prepared in Example 1 of this invention. YCOB is the abbreviation for YCa4O(BO3)3 crystal; La:YCOB is the abbreviation for La 0.1 :Y 0.9 The abbreviation for Ca4O(BO3)3 crystal.

[0025] Figure 3 This is an infrared-visible second-order nonlinear optical test of the lanthanum ion-doped yttrium borate oxygen-calcium nonlinear optical crystal prepared in Example 1 of this invention. La:YCOB represents La... 0.1 :Y 0.9 The abbreviation for Ca4O(BO3)3 crystal; KDP is the abbreviation for KH2PO4 crystal.

[0026] Figure 4 The images show the transmission contrast spectra of the lanthanum ion-doped calcium borate yttrium nonlinear optical crystal, calcium borate yttrium crystal, and lanthanum calcium borate yttrium prepared in Example 1 of this invention. La:YCOB represents La... 0.1 :Y 0.9 The abbreviation for Ca4O(BO3)3 crystal; YCOB is the abbreviation for YCa4O(BO3)3 crystal; LaCOB is the abbreviation for LaCa4O(BO3)3 crystal. Detailed Implementation

[0027] This invention provides a lanthanum ion-doped yttrium oxyborate nonlinear optical crystal material, characterized in that the lanthanum ion-doped yttrium oxyborate nonlinear optical crystal belongs to the monoclinic crystal system, point group m, space group Cm, and has the chemical formula La. 0.1 :Y 0.9 Ca4O(BO3)3 has unit cell parameters of a = 8.0737 ~ 8.183 Å, b = 16.0088 ~ 16.11 Å, c = 3.5283 ~ 3.623 Å, α = γ = 90°, and β = 101.166° ~ 101.36°.

[0028] Specifically, due to La 3+ With Y 3+ Elements belonging to the same group and having similar chemical structures, therefore, in crystal structures, Y... 3+ The location is easily affected by La 3+ The substitution results in the formation of lanthanum ion-doped calcium borate yttrium single crystals (hereinafter referred to as La:YCOB). Simultaneously, due to the differences in their electronic layers and radii, La... 3+Once it enters the crystal lattice, it causes changes in the crystal's lattice parameters. These changes further affect the nonlinear optical properties of the yttrium oxyborate crystal, giving it unique advantages and potential applications in nonlinear optics.

[0029] Tests have shown that, compared to undoped yttrium oxyborate (YCOB) crystals, lanthanum ion-doped yttrium oxyborate (La:YCOB) crystals exhibit a blue-shifted ultraviolet cutoff edge to below 200 nm and also possess a larger frequency doubling coefficient. This indicates that La:YCOB crystals have unique advantages and potential application prospects in nonlinear optics.

[0030] A second aspect of the present invention provides a method for preparing a lanthanum ion-doped yttrium oxyborate nonlinear optical crystal material as described in any one of the first aspects above, comprising: Step 1: Prepare lanthanum ion-doped calcium oxy borate polycrystalline material; Step 2: Place the yttrium oxyborate seed crystal at the bottom of the crucible, fill the top of the seed crystal with the polycrystalline material, and seal the crucible; Step 3: Place the crucible in the crystal growth furnace, raise the furnace temperature to melt both the polycrystalline material and the top of the seed crystal, complete the inoculation, and obtain the inoculated material; Step 4: Control the temperature gradient in the crystal growth furnace to decrease, so that the inoculated material crystallizes, is kept warm, and cooled to obtain lanthanum ion-doped yttrium oxyborate nonlinear optical crystal material.

[0031] In some embodiments, step 1 includes: Weigh out the raw materials CaCO3 or CaO, H3BO3 or B2O3, La2O3 and Y2O3 according to the stoichiometric ratio, and then add 1% to 10% of H3BO3 or B2O3 in an additional molar ratio, mix them evenly to obtain the mixture. The mixture is pressed into blocks and sintered and cooled at 1000℃~1100℃ to obtain the first sintered product. The first sintering product is crushed, ground, and pressed into blocks, and then sintered and cooled at 1200℃~1350℃ to obtain the lanthanum ion-doped calcium oxy borate polycrystalline material.

[0032] In some embodiments, the first sintering time is 12 to 20 hours, and the second sintering time is 24 to 40 hours.

[0033] In some embodiments, step 3 includes: The crucible is placed in a crystal growth furnace, and the part of the crucible containing the polycrystalline material is placed in the high-temperature zone of the crystal growth furnace. The temperature of the high-temperature zone is raised to the first melting temperature to melt the polycrystalline material and generate a polycrystalline molten liquid. The portion of the crucible placed on top of the seed crystal is placed in the temperature gradient zone of the crystal growth furnace, and the temperature of the temperature gradient zone is raised to the second melting temperature to melt the top of the seed crystal. The temperature is then maintained to complete the inoculation and obtain the inoculated material.

[0034] In some embodiments, raising the temperature of the high-temperature zone to a first melting temperature to melt the polycrystalline material and generate a polycrystalline melt includes: raising the temperature of the high-temperature zone to 1480°C to 1490°C within 10 hours, bringing the polycrystalline material to a fully molten state and overheating it by 50°C to 100°C, and holding it at that temperature for 24 to 48 hours to melt the polycrystalline material and obtain a polycrystalline melt. The step of raising the temperature of the temperature gradient zone to the second melting temperature to melt the top of the seed crystal, holding the temperature, and completing the inoculation to obtain the inoculated material includes: raising the temperature of the temperature gradient zone to 1410℃ ~ 1420℃ to melt the top of the seed crystal, holding the temperature for 2 hours ~ 3 hours, completing the inoculation, and obtaining the inoculated material.

[0035] In some embodiments, step 4 includes: The crucible is placed on the lowering device of the crystal growth furnace, and the lowering device is controlled to descend in the temperature gradient zone of the crystal growth furnace. After the inoculated material in the molten state in the crucible crystallizes, the descent is stopped, the temperature is maintained, and the material is cooled to obtain the lanthanum ion-doped calcium oxy borate polycrystalline material.

[0036] In some embodiments, along the descent direction of the crucible, the temperature in the temperature gradient zone decreases at a gradient of 30℃ / cm to 50℃ / cm, and the descent rate of the crucible is 6mm / day to 10mm / day. The heat preservation conditions are: constant temperature at 1200℃~1300℃ for 1.0 hour~2.0 hours; The cooling conditions are as follows: gradually cooling to room temperature at a rate of 30°C / hour to 50°C / hour.

[0037] In some embodiments, the chemical formula of the yttrium oxyborate seed crystal is YCa4O(BO3)3 single crystal.

[0038] In some embodiments, the crucible may be Ф9 × Φ50 × 300 mm in size.

[0039] The third aspect of the present invention provides the use of a crystal material prepared according to the lanthanum ion-doped calcium oxy borate nonlinear optical crystal material according to any one of the first aspects and the preparation method of the lanthanum ion-doped calcium oxy borate nonlinear optical crystal material according to any one of the second aspects, wherein the lanthanum ion-doped calcium oxy borate nonlinear optical crystal material is used in the preparation of piezoelectric crystal materials and sensor devices.

[0040] Specifically, the method for preparing lanthanum ion-doped yttrium oxyborate nonlinear optical crystals according to the present invention is the crucible lowering method, which has the following characteristics: (1) It can achieve crystal growth in directions other than the growth habit direction, flexibly meeting different application needs; (2) It uses a closed crucible, which effectively prevents external impurities from contaminating the crystal and the volatilization of melt components, ensuring crystal purity and chemical consistency; (3) It has better control over the growth rate, but the growth time is longer; (4) It is easy to control the crystal structure and morphology; (5) The growth process is simple; (6) It is not easy to generate bubbles inside the crystal; (7) The cost is low; (8) It can control the simultaneous growth of multiple crystals; (9) The axial temperature gradient is smaller than that of the Czochralski method, which is beneficial to overcoming the crystal cracking problem. In some embodiments, the method specifically includes: (1) Ingredients: After drying the raw materials calcium carbonate (CaCO3), lanthanum oxide (La2O3), and yttrium oxide (Y2O3) at 200℃, they are reacted with boric acid (H3BO3) according to the chemical formula La... 0.1 :Y 0.9 Weigh the substances according to the stoichiometric ratio of Ca4O(BO3)3, then add 1% to 10% of H3BO3 or B2O3 in molar ratio, and then mix thoroughly to obtain a mixture.

[0041] (2) Preparation of polycrystalline material: The mixture prepared in step (1) is placed in a muffle furnace and sintered for the first time at a constant temperature of 1000℃~1100℃ for 12 to 20 hours. After cooling to room temperature, the polycrystalline material after the first sintering is obtained. The polycrystalline material after the first sintering is crushed and ground to make it evenly mixed. It is then pressed into a round cake-shaped block and sintered for the second time at a constant temperature of 1200℃~1350℃ for 24 to 40 hours. After cooling to room temperature, the lanthanum ion-doped calcium oxy borate polycrystalline material after the second sintering is obtained. (3) Lanthanum ion-doped yttrium oxyborate (La) 0.1 :Y 0.9 Growth of Ca4O(BO3)3 single crystals: The polycrystalline material and seed crystal obtained in step (2) are sealed in a platinum crucible with dimensions of Ф9 × Φ50 × 300 mm, with the seed crystal located in the seed crystal well. The platinum crucible is then placed in a corundum tube, and alumina powder is filled between the corundum tube and the platinum crucible for heat preservation. The corundum tube and the platinum crucible are placed in a furnace. The corundum tube and the portion of the crucible containing the polycrystalline material are raised to the high-temperature zone. The program is set so that the temperature in the furnace in the high-temperature zone slowly rises to 1480°C within 10 hours, bringing the polycrystalline material to a fully molten state. The melt is then kept superheated by 50°C to 100°C for 24 to 48 hours to ensure that the polycrystalline material is fully melted and reaches a uniform state, resulting in a uniform high-temperature molten polycrystalline material.

[0042] Adjust the relative position of the crucible and the furnace body so that the top of the seed crystal is located in the temperature gradient zone of the crystal growth furnace. Control the temperature of the top of the seed crystal in the temperature gradient zone within the range of 1410℃ to 1420℃ and maintain it for 2 hours to complete the seeding.

[0043] The platinum crucible is controlled to descend within the temperature gradient zone of the crystal growth furnace, allowing the molten polycrystalline material in the crucible to gradually crystallize in the temperature field as the crucible descends. During crystal growth, the temperature gradient in the temperature gradient zone is 30℃~50℃ / cm along the direction of crucible descent. The crucible is controlled to descend at a rate of 6 mm / day~10 mm / day for single crystal growth until all the polycrystalline material in the crucible has crystallized, at which point the descent of the crucible is stopped. After single crystal growth is completed, the crystal is kept at a temperature of 1200℃ ~ 1300℃ in the furnace body temperature field for 1.0 to 2.0 hours, and then cooled to room temperature at a rate of 30℃ / hour to 50℃ / hour. The mechanical platform is then lowered, the platinum crucible is removed, and after peeling off the platinum crucible, lanthanum ion-doped calcium borate yttrium nonlinear optical crystal material is obtained.

[0044] The following description, in conjunction with specific embodiments and accompanying drawings, provides further details.

[0045] Example 1: A method for preparing a lanthanum ion-doped yttrium oxyborate nonlinear optical crystal material includes: (1) Ingredients According to the chemical formula (La) 0.1 :Y 0.9 The stoichiometric ratio of Ca4O(BO3)3 was determined by weighing the raw materials: calcium carbonate (CaCO3, 179.27 g, 1.79 mol), lanthanum oxide (La2O3, 7.29 g, 0.022 mol), yttrium oxide (Y2O3, 45.50 g, 0.20 mol), and boric acid (H3BO3, 84.72 g, 1.37 mol). An additional 1% to 10% molar ratio of H3BO3 was added, and the mixture was thoroughly mixed to obtain the final mixture.

[0046] (2) Preparation of polycrystalline materials The mixture prepared in step (1) is pressed into a disc-shaped block and placed in a muffle furnace. It is sintered at a constant temperature of 1100℃ for 12 hours. After cooling to room temperature, the polycrystalline material after the first sintering is obtained. The polycrystalline material after the first sintering is crushed and ground to make it evenly mixed. It is then pressed into a disc-shaped block and sintered at a constant temperature of 1350℃ for 24 hours. After cooling to room temperature, the lanthanum ion-doped calcium oxy borate polycrystalline material after the second sintering is obtained.

[0047] (3) La 0.1 :Y 0.9 Ca4O(BO3)3 single crystal growth The polycrystalline material and seed crystal obtained in step (2) are sealed in a platinum crucible with dimensions of Ф9 × Φ50 × 300 mm, with the seed crystal located in the seed crystal well. The platinum crucible is then placed in an alumina tube, and alumina powder is filled between the alumina tube and the platinum crucible for heat preservation. The alumina tube and the platinum crucible are placed in a furnace. The alumina tube and the crucible containing the polycrystalline material are raised to the high-temperature zone. The program is set so that the temperature in the furnace in the high-temperature zone slowly rises to 1480°C within 10 hours, bringing the polycrystalline material to a fully molten state. The melt is then kept 100°C superheated and held for 24 hours to ensure that the polycrystalline material is fully melted and reaches a uniform state, resulting in a uniform high-temperature molten polycrystalline material.

[0048] Adjust the relative position of the crucible and the furnace body so that the top of the seed crystal is located in the temperature gradient zone of the crystal growth furnace. Control the temperature of the top of the seed crystal in the temperature gradient zone at 1410 ℃ and maintain it for 2 hours to complete the seeding.

[0049] The platinum crucible is controlled to descend within the temperature gradient zone of the crystal growth furnace, allowing the molten polycrystalline material within the crucible to gradually crystallize in the temperature field as the crucible descends. During crystal growth, the temperature gradient in the temperature gradient zone is 50 °C / cm along the direction of crucible descent. The crucible is controlled to descend at a rate of 10 mm / day for single-crystal growth until all the polycrystalline material in the crucible has crystallized, at which point the descent of the crucible is stopped.

[0050] After single crystal growth, the crystal was kept at 1300 °C in the furnace temperature field for 1.0 hour, then cooled to room temperature at a rate of 50 °C / hour, and the mechanical platform was lowered. The platinum crucible was then removed, and after peeling off the platinum crucible, lanthanum ion-doped calcium borate yttrium nonlinear optical crystal material was obtained. Figure 1 ).

[0051] The crystal obtained in Example 1 was examined for its phase using an XPERT-PRO X-ray diffractometer (D8 ADVANCE DAVINCI, BRUKER, Germany). The phase was determined by Cu... Kα radiation (1.5406 Å) was used to record the crystal phase of the single crystal in the 2θ range of 10° to 70°, and compared with the XRD pattern of the standard YCOB (PDF# 50-0403) PDF card. The diffraction peaks of the La:YCOB crystal were basically consistent with those of the YCOB crystal, indicating that La:YCOB and YCOB have the same crystal structure. Figure 2 The frequency doubling factor of the crystal was measured using an infrared-visible second-order nonlinear optical measuring instrument (Mini NOTS 1064+2100), and was found to be 2.1 × KDP. Figure 3 The absorption spectrum of the crystal was measured using a spectrophotometer (Lambda 950, PerkinElmer, USA), with a test range of 200–2500 nm. It exhibited 80% transmittance in the 250–2500 nm range. Figure 4 Its wider transparent window is suitable for nonlinear optical devices, making it applicable to frequency conversion and other parametric processes.

[0052] Example 2: A method for preparing a lanthanum ion-doped yttrium oxyborate nonlinear optical crystal material includes: (1) Ingredients According to the chemical formula (La) 0.1 :Y 0.9 The stoichiometric ratio of Ca4O(BO3)3 was determined by weighing the raw materials: calcium carbonate (CaCO3, 179.27 g, 1.79 mol), lanthanum oxide (La2O3, 7.29 g, 0.022 mol), yttrium oxide (Y2O3, 45.50 g, 0.20 mol), and boric acid (H3BO3, 84.72 g, 1.37 mol). An additional 1% to 10% molar ratio of H3BO3 was added, and the mixture was thoroughly mixed to obtain the final mixture.

[0053] (2) Preparation of polycrystalline materials The mixture prepared in step (1) is pressed into a disc-shaped block and placed in a muffle furnace. It is sintered for 20 hours at a constant temperature of 1000℃. After cooling to room temperature, the polycrystalline material after the first sintering is obtained. The polycrystalline material after the first sintering is crushed and ground to make it evenly mixed. It is then pressed into a disc-shaped block and sintered for 40 hours at a constant temperature of 1200℃. After cooling to room temperature, the lanthanum ion-doped calcium oxy borate polycrystalline material after the second sintering is obtained.

[0054] (3) La0.1 :Y 0.9 Ca4O(BO3)3 single crystal growth The polycrystalline material and seed crystal obtained in step (2) were sealed in a platinum crucible with dimensions of Ф9 × Φ50 × 300 mm, with the seed crystal located in the seed crystal well. The platinum crucible was then placed in an alumina tube, and alumina powder was filled between the alumina tube and the platinum crucible for heat preservation. The alumina tube and the platinum crucible were placed in a furnace. The alumina tube and the crucible containing the polycrystalline material were raised to the high-temperature zone. The program was set so that the temperature in the furnace in the high-temperature zone slowly rose to 1480°C within 10 hours, bringing the polycrystalline material to a fully molten state. The melt was then kept 50°C superheated and held for 48 hours to ensure that the polycrystalline material was fully melted and reached a uniform state, resulting in a uniform high-temperature molten polycrystalline material.

[0055] Adjust the relative position of the crucible and the furnace body so that the top of the seed crystal is located in the temperature gradient zone of the crystal growth furnace. Control the temperature of the top of the seed crystal in the temperature gradient zone at 1415 ℃ and maintain it for 2 hours to complete the seeding.

[0056] The temperature inside the crystal growth furnace was maintained at a constant 1480 °C. The platinum crucible was controlled to descend within the temperature gradient zone of the crystal growth furnace, allowing the molten polycrystalline material in the crucible to gradually crystallize in the temperature field as the crucible descended. During crystal growth, the temperature gradient in the temperature gradient zone was 30 °C / cm along the direction of crucible descent. The crucible was controlled to descend at a rate of 6 mm / day for single crystal growth until all the polycrystalline material in the crucible had crystallized, at which point the descent of the crucible was stopped. After single crystal growth, the crystal was kept at 1200 °C in the furnace temperature field for 2.0 hours, then cooled to room temperature at a rate of 30 °C / hour. The mechanical platform was then lowered, the platinum crucible was removed, and after peeling off the platinum crucible, lanthanum ion-doped calcium borate yttrium nonlinear optical crystal material was obtained. Subsequently, the composition, structure, piezoelectric properties, and electrical conductivity of the material were tested.

[0057] Example 3: A method for preparing a lanthanum ion-doped yttrium oxyborate nonlinear optical crystal material includes: (1) Ingredients According to the chemical formula (La) 0.1 :Y 0.9 The stoichiometric ratio of Ca4O(BO3)3 was determined by weighing the raw materials: calcium carbonate (CaCO3, 179.27 g, 1.79 mol), lanthanum oxide (La2O3, 7.29 g, 0.022 mol), yttrium oxide (Y2O3, 45.50 g, 0.20 mol), and boric acid (H3BO3, 84.72 g, 1.37 mol). An additional 1% to 10% molar ratio of H3BO3 was added, and the mixture was thoroughly mixed to obtain the final mixture.

[0058] (2) Preparation of polycrystalline materials The mixture prepared in step (1) was placed in a muffle furnace and sintered for 16 hours at a constant temperature of 1050℃. After cooling to room temperature, the polycrystalline material after the first sintering was obtained. The polycrystalline material after the first sintering was crushed and ground to make it evenly mixed. It was pressed into a round cake-shaped block and sintered for 36 hours at a constant temperature of 1300℃. After cooling to room temperature, the lanthanum ion-doped calcium oxy borate polycrystalline material after the second sintering was obtained.

[0059] (3) La 0.1 :Y 0.9 Ca4O(BO3)3 single crystal growth The polycrystalline material and seed crystal obtained in step (2) were sealed in a platinum crucible with dimensions of Ф9 × Φ50 × 300 mm, with the seed crystal located in the seed crystal well. The platinum crucible was then placed in an alumina tube, and alumina powder was filled between the alumina tube and the platinum crucible for heat preservation. The alumina tube and the platinum crucible were placed in a furnace. The alumina tube and the crucible containing the polycrystalline material were raised to the high-temperature zone. The program was set so that the temperature in the furnace in the high-temperature zone slowly rose to 1480°C within 10 hours, bringing the polycrystalline material to a fully molten state. The melt was then kept at 80°C superheated for 36 hours to ensure that the polycrystalline material was fully melted and reached a uniform state, resulting in a uniform high-temperature molten polycrystalline material.

[0060] Adjust the relative position of the crucible and the furnace body so that the top of the seed crystal is located in the temperature gradient zone of the crystal growth furnace. Control the temperature of the top of the seed crystal in the temperature gradient zone at 1420℃ and maintain it for 2 hours to complete the seeding.

[0061] The temperature inside the crystal growth furnace is maintained at a constant 1480℃. The platinum crucible is controlled to descend within the temperature gradient zone of the crystal growth furnace, allowing the molten polycrystalline material in the crucible to gradually crystallize in the temperature field as the crucible descends. During crystal growth, the temperature gradient in the temperature gradient zone is 40℃ / cm along the direction of crucible descent. The crucible is controlled to descend at a rate of 8 mm / day for single crystal growth until all the polycrystalline material in the crucible has crystallized, at which point the descent of the crucible is stopped. After single crystal growth, the crystal was kept at 1250°C in the furnace temperature field for 2.0 hours, then cooled to room temperature at a rate of 40°C / hour. The mechanical platform was then lowered, the platinum crucible was removed, and after peeling off the platinum crucible, lanthanum ion-doped calcium oxy borate yttrium nonlinear optical crystal material was obtained. The composition, structure, and nonlinear optical properties of the material were then tested.

Claims

1. A lanthanum ion-doped yttrium oxyborate nonlinear optical crystal material, characterized in that, The lanthanum ion-doped calcium oxy borate yttrium nonlinear optical crystal belongs to the monoclinic crystal system, point group m, space group Cm, and has the chemical formula La. 0.1 :Y 0.9 Ca4O(BO3)3 has unit cell parameters of a = 8.0737 ~ 8.183 Å, b = 16.0088 ~ 16.11 Å, c = 3.5283 ~ 3.623 Å, α = γ = 90°, and β = 101.166° ~ 101.36°.

2. The lanthanum ion-doped yttrium oxyborate nonlinear optical crystal material according to claim 1, characterized in that, The crystal material has a frequency doubling factor of 2×KDP, an ultraviolet cutoff edge of less than 200 nm, and no intensity greater than or equal to 0.2 cm in the 200~3000 nm range. -1 The absorption peak.

3. A method for preparing a lanthanum ion-doped yttrium oxyborate nonlinear optical crystal material as described in any one of claims 1 to 2, characterized in that, include: Step 1: Prepare lanthanum ion-doped calcium oxy borate polycrystalline material; Step 2: Place the yttrium oxyborate seed crystal at the bottom of the crucible, fill the top of the seed crystal with the polycrystalline material, and seal the crucible; Step 3: Place the crucible in the crystal growth furnace, raise the furnace temperature to melt both the polycrystalline material and the top of the seed crystal, complete the inoculation, and obtain the inoculated material; Step 4: Control the temperature gradient in the crystal growth furnace to decrease, so that the inoculated material crystallizes, is kept warm, and cooled to obtain lanthanum ion-doped yttrium oxyborate nonlinear optical crystal material.

4. The preparation method according to claim 3, characterized in that, Step 1 includes: CaCO3, H3BO3, La2O3 and Y2O3 are mixed to obtain a mixture. The mixture is sintered at 1000℃~1100℃ and then cooled to obtain the first sintered product. The first sintering product is crushed, ground, and pressed into blocks, and then sintered and cooled at 1200℃~1300℃ to obtain the lanthanum ion-doped calcium oxy borate polycrystalline material.

5. The preparation method according to claim 4, characterized in that, The first sintering time is 12 to 20 hours, and the second sintering time is 24 to 40 hours.

6. The preparation method according to claim 3, characterized in that, Step 3 includes: The crucible is placed in a crystal growth furnace, and the part of the crucible containing the polycrystalline material is placed in the high-temperature zone of the crystal growth furnace. The temperature of the high-temperature zone is raised to the first melting temperature to melt the polycrystalline material and generate a polycrystalline molten liquid. The portion of the crucible placed on top of the seed crystal is placed in the temperature gradient zone of the crystal growth furnace, and the temperature of the temperature gradient zone is raised to the second melting temperature to melt the top of the seed crystal. The temperature is then maintained to complete the inoculation and obtain the inoculated material.

7. The preparation method according to claim 6, characterized in that, The step of raising the temperature of the high-temperature zone to the first melting temperature to melt the polycrystalline material and generate a polycrystalline melt includes: raising the temperature of the high-temperature zone to 1480°C to 1490°C within 10 hours, bringing the polycrystalline material to a fully molten state and overheating it by 50°C to 100°C, and holding it at that temperature for 24 to 48 hours to melt the polycrystalline material and obtain a polycrystalline melt. The step of raising the temperature of the temperature gradient zone to the second melting temperature to melt the top of the seed crystal, holding the temperature, and completing the inoculation to obtain the inoculated material includes: raising the temperature of the temperature gradient zone to 1410℃ ~ 1420℃ to melt the top of the seed crystal, holding the temperature for 2 hours ~ 3 hours, completing the inoculation, and obtaining the inoculated material.

8. The preparation method according to claim 3, characterized in that, Step 4 includes: The crucible is placed on the lowering device of the crystal growth furnace, and the lowering device is controlled to descend in the temperature gradient zone of the crystal growth furnace. After the inoculated material in the molten state in the crucible crystallizes, the descent is stopped, the temperature is maintained, and the material is cooled to obtain the lanthanum ion-doped calcium oxy borate polycrystalline material.

9. The preparation method according to claim 8, characterized in that, Along the direction of crucible descent, the temperature in the temperature gradient zone decreases at a gradient of 30℃ / cm to 50℃ / cm, and the crucible descent rate is 6mm / day to 10mm / day. The heat preservation conditions are: constant temperature at 1200℃~1300℃ for 1.0 hour~2.0 hours; The cooling conditions are as follows: gradually cooling to room temperature at a rate of 30°C / hour to 50°C / hour.

10. The use of a lanthanum ion-doped yttrium oxyborate nonlinear optical crystal material, characterized in that, The lanthanum ion-doped calcium oxy borate yttrium nonlinear optical crystal material is the lanthanum ion-doped calcium oxy borate yttrium nonlinear optical crystal material according to any one of claims 1 to 2 or the lanthanum ion-doped calcium oxy borate yttrium nonlinear optical crystal material according to any one of claims 3 to 9. The lanthanum ion-doped calcium oxy borate yttrium nonlinear optical crystal material is used in optical parametric chirped pulse amplification technology.

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