Compound telluric acid scandium rubidium second-order nonlinear optical crystal as well as preparation method and application thereof

Abstract

The invention discloses a compound rubidium scandium tellurate second-order nonlinear optical crystal as well as a preparation method and application thereof, and belongs to the technical field of optical crystal materials. The method comprises the following steps: mixing a scandium-containing compound, a rubidium-containing compound and a tellurium-containing compound, preparing the compound rubidium scandium tellurate by adopting a solid-phase reaction method, and heating and melting the obtained compound rubidium scandium tellurate single-phase polycrystalline powder or a mixture of the obtained compound rubidium scandium tellurate single-phase polycrystalline powder and a fluxing agent to obtain uniform mixed melt; or directly heating and melting a mixture of the scandium-containing compound, the rubidium-containing compound and the tellurium-containing compound or a mixture of the scandium-containing compound, the rubidium-containing compound, the tellurium-containing compound and the fluxing agent to obtain uniform mixed melt, and performing crystal growth to obtain the scandium-containing rubidium-tellurium-containing crystal. The crystal has stable physical and chemical properties, has potential application value, can be applied to nonlinear optical devices, such as laser frequency multipliers, can generate laser output different from incident light frequency, and provides new material selection and technical support for development of laser technology.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of nonlinear optics, in particular, the present application relates to a synthesis method of tellurite nonlinear optical crystal cesium rubidium tellurate and its application in nonlinear optical devices. BACKGROUND

[0002] Nonlinear optical (NLO) crystals are indispensable key components of all-solid-state lasers due to their ability to extend the laser wavelength. Currently, the traditional borate, phosphate and other nonlinear optical crystal materials applied in the ultraviolet-visible light waveband are the most mature, including commercialized crystals such as β-BaB2O4(BBO), LiB3O5(LBO), KBe2BO3F2(KBBF), CsLiB6O 10 (CLBO), KH2PO4(KDP), KTiOPO4(KTP) and the like. However, compared with the ultraviolet-visible light waveband, the NLO crystal types in the mid-infrared waveband are relatively few, mainly focusing on traditional chalcopyrite type crystals such as AgGaS2(AGS), AgGaSe2(AGSe), ZnGeP2(ZGP) and the like. Although these crystals have advantages such as large second-order nonlinear optical coefficient and wide transmission range, they have small intrinsic band gap, resulting in low laser damage threshold, serious two-photon absorption and other disadvantages, which limit their application range. Therefore, designing and synthesizing mid-infrared nonlinear optical crystals with excellent performance, especially those capable of breaking through the 3.0eV band gap "barrier", has become a scientific problem to be solved in the exploration of mid-infrared nonlinear optical crystal materials.

[0003] In recent years, tellurite systems have attracted widespread attention from researchers due to their unique structure and performance. In the tellurite system, Te and O atoms have rich coordination modes, which can form [TeO3] triangular pyramid, [TeO4] seesaw, [TeO5] and other polyhedral units that easily cause microstructure distortion. In addition, the heavy element tellurium atom is beneficial to widen the infrared absorption cutoff edge due to its inherent low phonon energy characteristics. Based on these characteristics, the introduction of rare earth cations Sc 3 + into the tellurite system on the one hand can improve the degree of structural distortion, thereby increasing the nonlinear optical effect, and on the other hand, the selection of rare earth cations without d-d and f-f electron transition is beneficial to increase the optical band gap. Therefore, the rare earth-containing tellurite is a potential new type of mid-infrared nonlinear optical crystal candidate system. SUMMARY

[0004] In view of the problems in the prior art, the present application introduces alkali metal cations Rb + and rare earth cations Sc 3+The introduction of a tellurite system containing a stereochemically active lone pair of electrons provides a second-order nonlinear optical crystal rubidium scandium tellurate RbScTe2O6 with excellent performance. The rubidium scandium tellurate crystal in the application is characterized in that the crystal has the following performance indexes: strong powder frequency doubling effect (> 2* KDP); short ultraviolet cutoff edge (< 240 nm); large optical band gap (> 4.0 eV); wide infrared transmission cutoff edge (> 5.0 μm); and the transmission range can effectively cover the key 3-5 μm atmospheric transmission window. Therefore, the excellent comprehensive performance of the rubidium scandium tellurate crystal makes it a potential mid-infrared nonlinear optical crystal.

[0005] The first object of the application is to provide a rubidium scandium tellurate nonlinear optical crystal with a chemical formula of RbScTe2O6.

[0006] The second object of the application is to provide a method for synthesizing the compound rubidium scandium tellurate by a high-temperature solid-phase method and growing the rubidium scandium tellurate nonlinear optical crystal by a high-temperature solution method.

[0007] The third object of the application is to provide an application of the rubidium scandium tellurate in nonlinear optical devices.

[0008] To achieve the above objects, the application adopts the following technical solutions:

[0009] The application provides a compound rubidium scandium tellurate with a chemical formula of RbScTe2O6. The preparation process of the compound is as follows: a rubidium-containing compound, a scandium-containing compound and a tellurium-containing compound are mixed, and are sufficiently ground in an agate mortar to make them uniformly mixed. The ground mixture is pre-fired at low temperature in a muffle furnace to remove water and gas in the raw materials. Then, the mixture is placed in a quartz tube, vacuumized and sealed. The temperature is slowly increased for continuous calcination, and finally cooled to room temperature to prepare a rubidium scandium tellurate powder polycrystal pure phase.

[0010] The scandium-containing compound includes at least one of scandium oxide, scandium sulfide, scandium hydroxide or a scandium salt; and the scandium salt includes at least one of scandium fluoride, scandium chloride, scandium nitrate and scandium sulfate.

[0011] The rubidium-containing compound includes at least one of rubidium oxide, rubidium hydroxide or a rubidium salt; and the rubidium salt includes at least one of rubidium chloride, rubidium fluoride and rubidium carbonate.

[0012] The tellurium-containing compound is tellurium dioxide.

[0013] The application adopts a high-temperature solid-phase synthesis method to prepare the compound rubidium scandium tellurate according to the following chemical reaction formula:

[0014] 1) Rb2CO3 + Sc2O3 + 4TeO2 → 2RbScTe2O6 + CO2↑

[0015] 2) Rb2O + Sc2O3 + 4TeO2→ 2RbScTe2O6

[0016] 3) 2RbOH + Sc2O3 + 4TeO2→ 2RbScTe2O6 + H2O

[0017] 4) 2Rb2SO4 + 2Sc2O3 + 8TeO2→ 4RbScTe2O6 + 2SO2↑ + O2↑

[0018] 5) 4RbNO3 + 2Sc2O3 + 8TeO2→ 4RbScTe2O6 + 4NO2↑ + O2↑

[0019] 6) Rb2O + Sc2(SO4)3 + 4TeO2→ 2RbScTe2O6 + 3SO2↑ + 1.5O2↑

[0020] 7) Rb2O + 2Sc(OH)3 + 4TeO2→ 2RbScTe2O6 + 3H2O

[0021] 8) Rb2O + 2Sc(NO3)3 + 4TeO2→ 2RbScTe2O6 + 6NO2↑ + 1.5O2↑

[0022] 9) 4RbClO3 + 2Sc2O3 + 8TeO2→ 4RbScTe2O6 + 4ClO2↑ + O2↑

[0023] 10) 2RbHCO3 + Sc2O3 + 4TeO2→ 2RbScTe2O6 + H2O + 2CO2↑

[0024] The application provides a tellurium acid scandate rubidium second-order nonlinear optical crystal, which is prepared by a high-temperature solid-phase synthesis method and has a chemical formula of RbScTe2O6. The tellurium acid scandate rubidium RbScTe2O6 has excellent comprehensive performance, including a powder frequency doubling effect stronger than 2×KDP (KH2PO4), an ultraviolet cutoff edge shorter than 240 nm, an infrared transmission cutoff edge longer than 5.0 μm, and stable physical and chemical properties. The tellurium acid scandate rubidium RbScTe2O6 belongs to a hexagonal system, a P63mc space group, and has a unit cell parameter of Z = 1, a molecular weight of 481.63. The structure of the tellurium acid scandate rubidium RbScTe2O6 is composed of distorted isolated [TeO3] triangular pyramid groups and [ScO6] octahedral groups.

[0025] The application provides a preparation method of a compound tellurium acid scandate rubidium second-order nonlinear optical crystal. The tellurium acid scandate rubidium second-order nonlinear optical crystal is grown by a flux method, and a specific growth scheme is as follows:

[0026] a. mixing the compound rubidium scandium tellurate single-phase polycrystalline powder or the compound rubidium scandium tellurate pure-phase polycrystalline powder with a fluxing agent uniformly, heating to 600-1200℃ at a temperature increasing rate of 10-100℃ / h, keeping the temperature for at least 24h, and slowly cooling the mixed solution to 300-900℃, wherein the molar ratio of the compound rubidium scandium tellurate pure-phase polycrystalline powder to the fluxing agent is 1:0-20;

[0027] or directly heating the mixture of the scandium-containing compound, the rubidium-containing compound and the tellurium-containing compound or the mixture of the scandium-containing compound, the rubidium-containing compound and the tellurium-containing compound and a fluxing agent to 600-1200℃ at a temperature increasing rate of 10-100℃ / h, keeping the temperature for not less than 24h, and cooling the mixed solution to 300-900℃, wherein the molar ratio of the scandium-containing compound, the rubidium-containing compound and the tellurium-containing compound to the fluxing agent is 1:1:4:0-30;

[0028] The fluxing agent mainly includes Rb2CO3, Rb2O, RbOH, Sc(NO3)3, TeO2 and MoO3, and in addition, a composite fluxing agent including one or more of Rb2CO3-Rb2O, Rb2CO3-RbOH, Rb2O-Sc(NO3)3, Rb2CO3-TeO2 or TeO2-Rb2CO3-MoO3.

[0029] The polycrystalline powder pure phase of the compound rubidium scandium tellurate provided by the application is synthesized by a high-temperature solid-phase method: mixing a scandium-containing compound, a rubidium-containing compound and a tellurium-containing compound at a molar ratio of 1:1:4, grinding them thoroughly to make them uniformly mixed, placing them in a Pt crucible and putting them into a muffle furnace, pre-burning for 24h to remove water and gas in the raw materials, then placing them in a quartz tube, vacuumizing and sealing, increasing the temperature to 500-700℃ for sintering for not less than 96h, and finally obtaining the polycrystalline powder pure phase of RbScTe2O6 after the reaction is finished and the temperature is decreased to room temperature.

[0030] b. preparing a rubidium scandium tellurate seed crystal: slowly decreasing the mixed solution obtained in step a to room temperature at a temperature decreasing rate of 0.1-10℃ / h, and obtaining the rubidium scandium tellurate seed crystal by spontaneous crystallization;

[0031] c. placing the Pt crucible containing the mixed solution prepared in step a into a molten salt furnace, fixing the seed crystal obtained in step b on a seed crystal rod by a platinum wire, and placing the seed crystal above the solution liquid surface. First, pre-heating the seed crystal for 30-40min, when the temperature is higher than the saturation point by 5-15℃, slowly immersing the seed crystal below the solution liquid surface, keeping the temperature for 5-20min to eliminate impurities on the surface of the seed crystal, and then decreasing the temperature to the saturation point temperature at a temperature decreasing rate of 0.2-1℃ / min;

[0032] d, then slowly cooling at a cooling rate of 1-5 ℃ / h, the seed rod rotating at 3-60 rpm, crystal growth, after the crystal grows to the desired size, the crystal is lifted to 1-2 cm above the liquid surface, then the temperature is reduced to room temperature at a cooling rate of 10-50 ℃ / h, finally the furnace is opened and the crystal is taken out, obtaining the rubidium scandium tellurate second-order nonlinear optical crystal.

[0033] The molar ratio of Rb2CO3 to Rb2O in the fluxing agent Rb2CO3-Rb2O system is 1-10:1-10; the molar ratio of Rb2CO3 to RbOH in the Rb2CO3-RbOH system is 1-8:1-10; the molar ratio of Rb2O to Sc(NO3)3 in the Rb2O-Sc(NO3)3 system is 1-6:1-10; the molar ratio of Rb2CO3 to TeO2 in the Rb2CO3-TeO2 system is 1-10:1-5; the molar ratio of Rb2CO3, TeO2 and MoO3 in the Rb2CO3-TeO2-MoO3 system is 2-10:1-20:1-5.

[0034] The rubidium scandium tellurate second-order nonlinear optical crystal obtained by the method can be prepared into a frequency doubling device, and under room temperature, using a Nd:YAG Q-switched laser light source, infrared light with a wavelength of 1064 nm is emitted, and after passing through the target crystal, green laser with a wavelength of 532 nm can be outputted. BRIEF DESCRIPTION OF DRAWINGS

[0035] Figure 1 It is an X-ray diffraction pattern of RbScTe2O6 powder.

[0036] Figure 2 It is a crystal structure unit cell diagram of RbScTe2O6.

[0037] Figure 3 It is an infrared spectrum diagram of RbScTe2O6.

[0038] Figure 4 It is a typical application schematic diagram of RbScTe2O6 crystal, wherein 1 is a light source, 2 is an incident laser beam, 3 is RbScTe2O6 crystal, 4 is a generated laser beam, and 5 is a filter. DETAILED DESCRIPTION

[0039] In order to further illustrate the present application, the present application is further described below in conjunction with examples, but the scope of protection required by the present application is not limited to the scope expressed in the examples.

[0040] Example 1:

[0041] The reaction equation for the synthesis of pure-phase RbScTe2O6 is: Rb2CO3+Sc2O3+4TeO2→2RbScTe2O6+CO2↑

[0042] The analytical pure Rb2CO3, Sc2O3 and TeO2 raw materials were weighed in a molar ratio of 1:1:4, ground, mixed uniformly, and then transferred to a Φ70 mm x 70 mm Pt crucible, which was placed in a muffle furnace. The temperature was raised to 300°C for 24 h for pre-sintering to remove moisture and gas in the raw materials. Subsequently, the sample was placed in a quartz tube, vacuumized and sealed. The temperature was raised to 600°C for calcination for not less than 96 h. Finally, the heating was stopped, and the sample was cooled to room temperature with the furnace. A white powder was obtained, which was the pure phase of RbScTe2O6. The powder X-ray diffraction pattern of the sample was obtained by powder X-ray diffraction test, as shown in FIG. 1. Figure 1 ;

[0043] The prepared pure phase polycrystalline powder of the compound rubidium scandium tellurate RbScTe2O6 was mixed with a fluxing agent TeO2 at a molar ratio of 1:2 and ground thoroughly, and then loaded into a Φ70 mm x 70 mm Pt crucible. The mixed raw materials were heated to about 800°C at a temperature rising rate of 50-80°C / h. After the raw materials and the fluxing agent were melted, the high-temperature solution in the Pt crucible was continuously maintained at a uniform temperature for 10-12 h. At the same time, a platinum wire was slowly lowered below the solution surface, and then the temperature was lowered to induce spontaneous crystallization. The crystal has a chemical formula of RbScTe2O6, crystallizes in a non-centrosymmetric hexagonal crystal system space group P63mc, has a wide transmittance range, an infrared cutoff edge wider than 5.0 μm, and stable physical and chemical properties and is not easy to deliquesce, as shown in FIG. 2. Figure 2 ,3.

[0044] The solution was slowly cooled at a rate of 1-5°C / h to obtain rubidium scandium tellurate grains;

[0045] The small grains of RbScTe2O6 obtained by spontaneous crystallization were used as seeds to grow rubidium scandium tellurate crystals by top seeded solution growth (TSSG) technology. The seeds were fixed on a seed rod by a platinum wire, preheated at a position 1-2 cm above the solution surface, slowly lowered into the solution surface at a temperature 5-15°C higher than the saturation point, maintained for 30-40 min to remove surface impurities, and then the temperature was lowered to the saturation point;

[0046] The temperature was further lowered at a rate of 0.5-3°C / day, the seed rod rotated at a speed of 5-60 rpm, and after the growth was completed, the crystal was lifted to a position 1-2 cm above the solution surface, and then cooled to room temperature at a rate of 10-50°C / h. Then the crystal was taken out to obtain the RbScTe2O6 crystal.

[0047] The raw material rubidium carbonate in the reaction formula can be replaced by rubidium fluoride, rubidium oxide, rubidium hydroxide, rubidium chloride or rubidium sulfate and other other lead-containing salts, and scandium oxide can be replaced by scandium nitrate, scandium sulfate or scandium chloride.

[0048] Example 2:

[0049] RbScTe2O6 pure phase synthesis, the reaction equation is: Rb2O + Sc2O3 + 4TeO2→ 2RbScTe2O6

[0050] The prepared compound of RbScTe2O6 pure phase polycrystalline powder is mixed with Rb2CO3-Rb2O flux in a molar ratio of 1:1 and ground uniformly, and the molar ratio of the flux Rb2CO3 to Rb2O is 1:2. The mixed sample is placed in a Φ70mm×70mm Pt crucible, and the mixed raw materials are heated to 750-850℃ at a heating rate of 50-80℃ / h. After the mixture is melted, continue to heat for 10-12h to make the high-temperature solution in the Pt crucible melt uniformly. The platinum wire is lowered below the solution surface, and slow cooling is performed for spontaneous crystallization.

[0051] The solution is slowly cooled at a cooling rate of 1-5℃ / h to obtain RbScTe2O6 crystal grains;

[0052] The RbScTe2O6 crystal grains obtained by spontaneous crystallization are used as seed crystals for crystal growth. The seed crystal is fixed on the seed crystal rod using a platinum wire, and the seed crystal is first placed 1-2cm above the liquid surface for preheating treatment, and then slowly immersed below the solution surface at a temperature 5-15℃ higher than the saturation point temperature for 30-40min to remove surface impurities, and then the temperature is reduced to the saturation point temperature;

[0053] The temperature is then reduced at a rate of 0.5-3℃ / day, the rotation speed of the crystal is 25-30rpm, and automatic forward and reverse rotation is adopted. After the crystal growth is completed, the crystal is raised to 1-2cm above the liquid surface, and the temperature is reduced to room temperature at a rate of 10-50℃ / h to obtain RbScTe2O6 crystal.

[0054] The raw material of rubidium carbonate in the reaction formula can be replaced by rubidium fluoride or rubidium oxide or rubidium hydroxide or rubidium chloride or rubidium sulfate and other other lead-containing salts, and scandium oxide can be replaced by scandium nitrate or scandium sulfate or scandium chloride.

[0055] Example 3:

[0056] RbScTe2O6 pure phase synthesis, the reaction equation is: 2RbOH + Sc2O3 + 4TeO2→ 2RbScTe2O6 + H2O

[0057] The prepared pure phase polycrystalline powder of the compound scandium tellurite such as RbScTe2O6 is mixed with a fluxing agent Rb2CO3-RbOH at a molar ratio of 1:1 and ground uniformly, wherein the molar ratio of Rb2CO3 to RbOH is 2:1, the ground raw material mixture is placed in a Φ70mm×70mm Pt crucible, the mixed raw material is heated to 750-850℃ at a heating rate of 50-80℃ / h, and the high-temperature solution in the Pt crucible is melted uniformly after the crystal growth raw material and the fluxing agent are completely melted and then kept constant for 10-15h. A platinum wire is immersed below the solution surface, and then slowly cooled for spontaneous crystallization;

[0058] The solution is slowly cooled at a cooling rate of 1-5℃ / h to obtain RbScTe2O6 grains;

[0059] The small grains of RbScTe2O6 obtained by spontaneous crystallization are used as seeds for crystal growth. A platinum wire is used to fix the seeds below the seed rod liquid surface, and the surface impurities are removed by keeping for 30-40min, and then the temperature is lowered to the saturation point temperature;

[0060] The temperature is then lowered at a rate of 0.5-3℃ / day, the rotation speed of the crystal is 25-30rpm, and automatic forward and reverse rotation is adopted. After the crystal growth is completed, the crystal is raised to 1-2cm above the liquid surface, and the temperature is lowered to room temperature at a rate of 10-50℃ / h, thereby obtaining RbScTe2O6 crystals.

[0061] The raw material rubidium carbonate in the reaction formula can be replaced with rubidium fluoride, rubidium oxide, rubidium hydroxide, rubidium chloride, or rubidium sulfate and other other lead-containing salts, and scandium oxide can be replaced with scandium nitrate, scandium sulfate, or scandium chloride.

[0062] Example 4:

[0063] The reaction equation for the synthesis of pure phase RbScTe2O6 is: Rb2O+2Sc(NO3)3+4TeO2→2RbScTe2O6+6NO2↑+1.5O2↑

[0064] The prepared pure phase polycrystalline powder of the compound scandium tellurite such as RbScTe2O6 is mixed with a fluxing agent Rb2CO3-RbOH at a molar ratio of 1:1 and ground uniformly, wherein the molar ratio of Rb2CO3 to RbOH is 2:1, the ground raw material mixture is placed in a Φ70mm×70mm Pt crucible, the mixed raw material is heated to 750-850℃ at a heating rate of 50-80℃ / h, and the high-temperature solution in the Pt crucible is melted uniformly after the crystal growth raw material and the fluxing agent are completely melted and then kept constant for 10-15h. A platinum wire is immersed below the solution surface, and then slowly cooled for spontaneous crystallization;

[0065] The solution is slowly cooled at a cooling rate of 1-5℃ / h to obtain RbScTe2O6 crystal grains;

[0066] The RbScTe2O6 small crystal grains obtained by spontaneous crystallization are used as seeds for crystal growth. The seeds are fixed on a seed rod using a platinum wire, and the seeds are first placed 1-2 cm above the liquid surface for preheating treatment, and then slowly immersed below the liquid surface of the solution at a temperature 5-15℃ higher than the saturation point temperature, and kept for 30-40 min to remove surface impurities, and then the temperature is lowered to the saturation point temperature;

[0067] The temperature is then lowered at a rate of 0.5-3℃ / day, the rotation speed of the crystal is 25-30 rpm, and automatic forward and reverse rotation is adopted. After the crystal growth is completed, the crystal is raised to 1-2 cm above the liquid surface, and the temperature is lowered to room temperature at a rate of 10-50℃ / h, and RbScTe2O6 crystal is obtained.

[0068] The raw material rubidium carbonate in the reaction formula can be replaced by rubidium fluoride, rubidium oxide, rubidium hydroxide, rubidium chloride or other lead-containing salts, and scandium oxide can be replaced by scandium nitrate, scandium sulfate or scandium chloride.

[0069] Example 5:

[0070] The reaction equation for the synthesis of pure-phase RbScTe2O6 is: Rb2SO4+Sc2O3+4TeO2→2RbScTe2O6+SO2↑+0.5O2↑

[0071] The prepared pure-phase polycrystalline powder of the compound RbScTe2O6 is mixed with a fluxing agent Rb2CO3-TeO2 at a molar ratio of 1:1 and ground uniformly, the molar ratio of Rb2CO3 to TeO2 is 1:1, the ground raw material mixture is placed in a Φ70mm×70mm Pt crucible, the mixed raw materials are heated to 750-850℃ at a heating rate of 50-80℃ / h, and the crystal growth raw materials and the fluxing agent are completely melted and then kept at a constant temperature for 10-15h to make the high-temperature solution in the Pt crucible melt uniformly. A platinum wire is immersed below the solution surface, and then slowly cooled for spontaneous crystallization;

[0072] The solution is slowly cooled at a cooling rate of 1-5℃ / h to obtain RbScTe2O6 crystal grains;

[0073] The RbScTe2O6 small crystal grains obtained by spontaneous crystallization are used as seeds for crystal growth. The seeds are fixed on a seed rod using a platinum wire, and the seeds are first placed 1-2 cm above the liquid surface for preheating treatment, and then slowly immersed below the liquid surface of the solution at a temperature 5-15℃ higher than the saturation point temperature, and kept for 30-40 min to remove surface impurities, and then the temperature is lowered to the saturation point temperature;

[0074] Then, the temperature is decreased at a rate of 0.5-3 ℃ / day, the rotation speed of the crystal is 25-30 rpm, and automatic forward and reverse rotation is adopted. After the crystal growth is completed, the crystal is raised to 1-2 cm above the liquid surface, and the temperature is decreased to room temperature at a rate of 10-50 ℃ / h, so that the RbScTe2O6 crystal is obtained.

[0075] The raw material rubidium carbonate in the reaction formula can be replaced by rubidium fluoride, rubidium oxide, rubidium hydroxide, rubidium chloride, rubidium sulfate or other lead-containing salts, and the scandium oxide can be replaced by scandium nitrate, scandium sulfate or scandium chloride.

[0076] Example 6:

[0077] The reaction formula for synthesizing the pure phase of RbScTe2O6 is: Rb2O + Sc2(SO4)3 + 4TeO2→ 2RbScTe2O6 + 3SO2↑ + 1.5O2↑

[0078] The prepared pure phase polycrystalline powder of the compound rubidium scandium tellurate RbScTe2O6 is mixed with a fluxing agent Rb2CO3-TeO2-MoO3 at a molar ratio of 1:1 and ground uniformly, wherein the molar ratio of Rb2CO3 to TeO2 to MoO3 is 1:15:1. The ground raw material mixture is placed in a Φ70 mm×70 mm Pt crucible, the mixed raw materials are heated at a heating rate of 50-80 ℃ / h to 750-850 ℃, and after the crystal growth raw materials and the fluxing agent are completely melted, the temperature is kept constant for 10-15 h to make the high-temperature solution in the Pt crucible melt uniformly. A platinum wire is immersed below the solution surface, and then slowly cooled for spontaneous crystallization;

[0079] The solution is slowly cooled at a rate of 1-5 ℃ / h to obtain rubidium scandium tellurate crystal grains;

[0080] The small crystal grains of RbScTe2O6 obtained by spontaneous crystallization are used as seeds for crystal growth. A platinum wire is used to fix the seeds on a seed rod, the seeds are first placed 1-2 cm above the liquid surface for preheating treatment, and then the seeds are slowly immersed below the solution surface at a temperature 5-15 ℃ higher than the saturation point temperature, and kept for 30-40 min to remove surface impurities, and then the temperature is decreased to the saturation point temperature.

[0081] Then, the temperature is decreased at a rate of 0.5-3 ℃ / day, the rotation speed of the crystal is 25-30 rpm, and automatic forward and reverse rotation is adopted. After the crystal growth is completed, the crystal is raised to 1-2 cm above the liquid surface, and the temperature is decreased to room temperature at a rate of 10-50 ℃ / h, so that the RbScTe2O6 crystal is obtained.

[0082] The raw material rubidium carbonate in the reaction formula can be replaced by rubidium fluoride, rubidium oxide, rubidium hydroxide, rubidium chloride, rubidium sulfate or other lead-containing salts, and the scandium oxide can be replaced by scandium nitrate, scandium sulfate or scandium chloride.

[0083] Example 7:

[0084] The RbScTe2O6 crystal obtained by the above method is used to prepare nonlinear optical devices:

[0085] The RbScTe2O6 nonlinear optical crystals obtained in Examples 1-4 are oriented and processed according to the crystallographic data and the required thickness, angle, and size, and the light-transmitting surface is polished, and can be used as nonlinear optical devices.

[0086] According to the attached Figure 4 As shown, the obtained crystal 3 is fixed between the light source 1 and the filter 5. At room temperature, a Nd:YAG Q-switched laser light source is used. After the incident infrared light beam 2 with a wavelength of 1064nm is incident on the crystal 3, the outgoing light beam 4 contains infrared light with a wavelength of 1064nm and green light of 532nm. After passing through the filter 5, a green laser with a wavelength of 532nm is obtained.

[0087] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and substitutions can be made without departing from the technical principles of the present invention. These improvements and substitutions should also be regarded as the scope of protection of the present invention.

Claims

1. A compound scandium telluride rubidium second-order nonlinear optical crystal, characterized in that: Its chemical formula is RbScTe2O6.

2. The compound scandium telluride rubidium nonlinear optical crystal according to claim 1, characterized in that: The scandium telluride rubidium telluride RbScTe2O6 belongs to the hexagonal system, P63mc space group, and the unit cell parameters are The molecular weight is 481.

63.

3. The method for preparing the scandium-rubidium telluride second-order nonlinear optical crystal according to claim 1 or 2, characterized in that: Scandium telluride rubidium nonlinear optical pure phase polycrystal and single crystal are prepared by solid phase reaction method and flux method respectively, including the following steps: a. Mixing a scandium-containing compound, a rubidium-containing compound, and a tellurium-containing compound to prepare the compound scandium-rubidium tellurate RbScTe2O6 by a solid-phase reaction method, wherein the molar ratio of the scandium element in the scandium-containing compound, the rubidium element in the rubidium-containing compound, and the tellurium element in the tellurium-containing compound is 1:1:4; b. The scandium-rubidium telluride compound is synthesized by a high-temperature solid-phase method. The specific process is as follows: raw materials containing a scandium compound, a rubidium compound, and a tellurium compound are mixed, ground and mixed uniformly using an agate mortar, placed in a muffle furnace, and pre-calcined at a low temperature to remove moisture and gas from the raw materials. The raw materials are then placed in a quartz tube, evacuated and sealed, and the temperature is slowly increased and calcined. Finally, the mixture is cooled to room temperature to synthesize the scandium-rubidium telluride compound. The scandium-containing compound includes at least one of scandium oxide, scandium sulfide, scandium hydroxide or a scandium salt; the scandium salt includes at least one of scandium fluoride, scandium chloride, scandium nitrate and scandium sulfate; The rubidium-containing compound includes at least one of rubidium oxide, rubidium hydroxide or a rubidium salt; the rubidium salt includes at least one of rubidium chloride, rubidium fluoride and rubidium carbonate; The tellurium-containing compound is tellurium dioxide; heating any of the obtained scandium and rubidium telluride compound single-phase polycrystalline powders or a mixture of any of the obtained scandium and rubidium telluride compound single-phase polycrystalline powders and a flux to obtain a uniform mixed melt; or directly heating and melting a mixture of the scandium-containing compound, the rubidium-containing compound and the tellurium-containing compound or a mixture of the scandium-containing compound, the rubidium-containing compound and the tellurium-containing compound and a flux to obtain a uniform mixed melt; c. Placing the Pt crucible containing the mixed solution prepared in step b in a molten salt furnace, and fixing a lead titanium telluride seed crystal to one end of a seed crystal rod using a platinum wire. First, preheating the seed crystal by placing it 1-2 cm above the liquid surface for 30-40 minutes. When the temperature is 5-15°C above the saturation point, slowly immerse the seed crystal below the liquid surface for 5-20 minutes to melt away surface impurities or defects. Then, lower the temperature to below the saturation temperature at a cooling rate of 0.2-1°C / min or maintain a constant temperature to obtain a scandium telluride rubidium nonlinear optical crystal.

4. The method for preparing the compound scandium telluride rubidium nonlinear optical crystal according to claim 3, characterized in that: The molar ratio of the scandium and rubidium telluride pure phase polycrystalline powder to the flux is 1:0-20; the molar ratio of the scandium-containing compound, the rubidium-containing compound and the tellurium-containing compound to the flux is 1:1:4:0-30.

5. The method for preparing the compound scandium telluride rubidium nonlinear optical crystal according to claim 3, characterized in that: Step a: After mixing the scandium-containing compound, the rubidium-containing compound and the tellurium-containing compound, pre-sintering for 24 hours to remove moisture and gas in the raw materials, placing them in a quartz tube, evacuating and sealing, raising the temperature to 500-700°C and sintering for not less than 96 hours, and cooling to room temperature after the reaction is completed.

6. The method for preparing the compound scandium telluride rubidium nonlinear optical crystal according to claim 3, characterized in that: In step b, the scandium telluride compound single-phase polycrystalline powder or the scandium telluride compound pure-phase polycrystalline powder is mixed evenly with a flux, heated to 600-1200°C at a heating rate of 10-100°C / h, kept at this temperature for at least 24 hours, and the mixed solution is slowly cooled to 300-900°C.

7. The method for preparing the compound scandium telluride rubidium nonlinear optical crystal according to claim 3, characterized in that: In step b, a mixture of a scandium-containing compound, a rubidium-containing compound and a tellurium-containing compound, or a mixture of a scandium-containing compound, a rubidium-containing compound and a tellurium-containing compound and a flux is directly heated to 600-1200°C at a heating rate of 10-100°C / h, and the temperature is kept constant for not less than 24 hours, and the mixed solution is cooled to 300-900°C.

8. The method for preparing the compound scandium telluride rubidium nonlinear optical crystal according to claim 3, characterized in that: The flux includes Rb2CO3, Rb2O, RbOH, Sc(NO3)3, TeO2 or MoO3, and a composite flux including one or more of Rb2CO3-Rb2O, Rb2CO3-RbOH, Rb2O-Sc(NO3)3, Rb2CO3-TeO2, or TeO2-Rb2CO3-MoO3.

9. The method for preparing the compound scandium telluride rubidium nonlinear optical crystal according to claim 3, characterized in that: The molar ratio of Rb2CO3 to Rb2O in the composite flux Rb2CO3-Rb2O system is 1-10:1-10; the molar ratio of Rb2CO3 to RbOH in the Rb2CO3-RbOH system is 1-8:1-10; the molar ratio of Rb2O to Sc(NO3)3 in the Rb2O-Sc(NO3)3 system is 1-6:1-10; the molar ratio of Rb2CO3 to TeO2 in the Rb2CO3-TeO2 system is 1-10:1-5; the molar ratio of Rb2CO3 to TeO2 to MoO3 in the Rb2CO3-TeO2-MoO3 system is 2-10:1-20:1-5.

10. Use of the compound scandium telluride rubidium nonlinear optical crystal according to claim 1 or 2, characterized in that: The scandium telluride rubidium nonlinear optical crystal is used to manufacture a frequency doubling generator, an up-frequency converter, a down-frequency converter and an optical parametric oscillator.

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