Compound titanium lead tellurate nonlinear optical crystal as well as preparation method and application thereof

Abstract

The invention provides a lead titanium tellurate second-order nonlinear optical crystal and a preparation method and application thereof, and belongs to the technical field of optical crystal materials. The compound is prepared by a solid-phase synthesis method and a fluxing agent method, and the preparation method comprises the step of growing the titanium lead tellurate nonlinear optical crystal by adopting the fluxing agent method. The obtained product has the advantages of large frequency-doubled effect, large optical band gap, wide transmission range, stable physical and chemical properties and difficulty in deliquescence, and can be used for preparing near-intermediate infrared nonlinear optical frequency conversion devices.

Description

Technical Field

[0001] This invention relates to the field of nonlinear optics, specifically to the synthesis of a tellurate nonlinear optical crystal, lead titanium tellurate, and its application in nonlinear optical devices. Background Technology

[0002] Non-centrosymmetric (NCS) materials have attracted widespread attention from scientists due to their diverse properties, including frequency conversion, thermoelectricity, piezoelectricity, and ferroelectricity. Among these, second-order nonlinear optical (NLO) crystals have become an important component of all-solid-state lasers, playing a crucial role in extending the wavelength of existing laser sources through laser frequency conversion. Over the past few decades, various NLO crystals, such as LiNbO3 (LN), KH2PO4 (KDP), KTiOPO4 (KTP), β-BaB2O4 (BBO), LiB3O5 (LBO), KBa2BO3F2 (KBBF), AgGaQ2 (Q = Se, S), and ZnGeP2 (ZGP), have been widely applied in various laser-related fields. However, each of these NLO crystals possesses some intrinsic defects. For example, borate and phosphate NLO crystals have limited mid-infrared (<5 μm) transmission range, while traditional sulfur and phosphorus compounds have low laser-induced damage thresholds due to narrow band gaps and poor two-photon absorption, which severely limits their further applications. Therefore, it is crucial to explore novel NLO crystals with superior performance and overcome these limitations.

[0003] Among various oxide systems, tellurates have attracted widespread attention from researchers due to their structural diversity and wide mid-infrared transmission range, making them a promising candidate for exploring mid-infrared nonlinear optical crystals. This research involves introducing Pb with second-order SOJT (Sodium-Jetel-Teller) distortion into the tellurate system. 2+ and Ti 4+ This not only enhances the second-order micropolarizability, thus achieving stronger second-order nonlinear optical effects, but also expands the mid-infrared transmission range. Therefore, lead-titanium tellurates are considered an ideal system for exploring novel high-performance mid-infrared nonlinear optical crystals. Summary of the Invention This invention will use Te 6+ Pb ions, main group cations with stereochemically active lone pairs of electrons 2+ and d 0 Transition metal cation Ti 4+ By combining these methods, a high-performance second-order nonlinear optical crystal, lead titanium tellurate, is obtained. The lead titanium tellurate crystal of this invention has an ultraviolet cutoff edge of 403 nm and an infrared transmittance of 730 cm⁻¹. -1The light transmittance does not decrease significantly, and its transmission range can effectively cover the critical 3-5 μm atmospheric transmission window, while also exhibiting a large powder overtone response. Therefore, lead titanium tellurate crystal is a mid-infrared nonlinear optical crystal with potential applications.

[0004] The first objective of this invention is to provide a lead titanium telluride nonlinear optical crystal with the chemical formula Pb₄Ti₃TeO. 13 ;

[0005] The second objective of this invention is to provide a method for preparing and growing lead titanium tellurate crystals using a high-temperature solid-state method and a flux method.

[0006] The third objective of this invention is to provide the application of lead titanium tellurate in nonlinear optical devices.

[0007] To achieve the above objectives, the present invention adopts the following technical solution:

[0008] The compound provided by this invention, lead titanium tellurate, has the chemical formula Pb₄Ti₃TeO. 13 The preparation process of this compound is as follows: lead-containing compound, titanium-containing compound and tellurium-containing compound raw materials are mixed and ground thoroughly with an agate mortar to make them evenly mixed. The ground mixture is placed in a muffle furnace for low-temperature pre-calcination to remove moisture and gas from the raw materials. The temperature is slowly increased and calcination is continued. The mixture is taken out and ground repeatedly during the process. Finally, it is cooled to room temperature to prepare polycrystalline pure phase titanium lead tellurate powder.

[0009] The lead-containing compound includes at least one of lead oxide, lead sulfide, lead hydroxide, or lead salts; the lead salts include at least one of lead fluoride, lead chloride, lead carbonate, and lead sulfate.

[0010] The titanium-containing compound includes at least one of titanium oxide, titanium hydroxide, or titanium salts; the titanium salts include at least one of titanium chloride and titanium fluoride.

[0011] The tellurium-containing compound is tellurium dioxide.

[0012] Lead titanium tellurate was prepared using a high-temperature solid-state synthesis method according to the following chemical reaction formula:

[0013] 1)4PbO+3TiO2+TeO2+0.5O2→Pb4Ti3TeO 13

[0014] 2)4PbF2+3TiO2+TeO2+2.5O2→Pb4Ti3TeO 13 +4F2↑

[0015] 3)4Pb(OH)2+3TiO2+TeO2+0.5O2→Pb4Ti3TeO 13 +4H2O↑

[0016] 4)4PbS+3TiO2+TeO2+6.5O2→Pb4Ti3TeO 13 +4SO2↑

[0017] 5)4PbCl2+3TiO2+TeO2+2.502→Pb4Ti3TeO 13 +4Cl2↑

[0018] 6)4PbCO3+3TiO2+TeO2+0.5O2→Pb4Ti3TeO 13 +4CO2↑

[0019] 7)4PbSO4+3TiO2+TeO2→Pb4Ti3TeO 13 +4SO2↑+1.5O2↑

[0020] 8)4PbO+3Ti(OH)4+TeO2+0.5O2→Pb4Ti3TeO 13 +6H2O↑

[0021] 9)4PbO+3TiCl4+TeO2+3.5O2→Pb4Ti3TeO 13 +6Cl2↑

[0022] 10)4PbO+3TiF4+TeO2+3.5O2→Pb4Ti3TeO 13 +6F2↑

[0023] The pure phase of the lead titanium tellurate second-order nonlinear optical crystal provided by this invention is prepared by a high-temperature solid-state synthesis method, and its chemical formula is Pb4Ti3TeO. 13 The ultraviolet cutoff edge is 403 nm, and the infrared spectral transmittance is at 730 cm⁻¹. 1 There was no significant decrease in the permeability, and it had a wide permeability range and stable physicochemical properties.

[0024] This invention provides a method for preparing a second-order nonlinear optical crystal of lead titanium tellurate. The method employs a flux method to grow the second-order nonlinear optical crystal of lead titanium tellurate, and the specific growth scheme is as follows:

[0025] a. Mix the pure-phase polycrystalline titanium lead tellurate powder with the flux evenly, heat it to 700-1200℃ at a heating rate of 10-100℃ / h, keep it at this temperature for at least 24h, and slowly cool the mixed solution to 300-900℃, wherein the molar ratio of the pure-phase polycrystalline titanium lead tellurate powder to the flux is 1:0-20.

[0026] Alternatively, a mixture of lead-containing compounds, titanium-containing compounds, and tellurium-containing compounds, or a mixture of lead-containing compounds, titanium-containing compounds, and tellurium-containing compounds with flux, can be heated to 700-1200℃ at a heating rate of 10-100℃ / h, held at that temperature for no less than 24h, and then cooled to 300-900℃, wherein the molar ratio of lead-containing compounds, titanium-containing compounds, and tellurium-containing compounds to flux is 4∶3∶1∶0-30;

[0027] The fluxes mainly include PbO, PbF2, Li2CO3, TeO2, and TiF4. In addition, there are composite fluxes, including PbO-PbF2 and TiF4. e One or more of O2-PbO, TiF4-PbO, or TeO2-PbO-PbF2.

[0028] The polycrystalline pure phase of lead titanium tellurate provided by this invention is synthesized by a high-temperature solid-state method: A lead-containing compound, a titanium-containing compound, and a tellurium-containing compound are mixed in a molar ratio of 4:3:1, thoroughly ground to ensure homogeneity, placed in a Pt crucible and then placed in a muffle furnace. Pre-calcination is performed for 24 hours to remove moisture and gases from the raw materials. The temperature is then increased to 600-800℃ and sintered for at least 72 hours, with repeated grinding during this period. After the reaction is complete, the mixture is cooled to room temperature to finally obtain Pb₄Ti₃TeO. 13 Pure phase of polycrystalline powder.

[0029] b. Preparation of lead titanium tellurate seed crystals: The mixed solution obtained in step a is slowly cooled to room temperature at a cooling rate of 0.1-10℃ / h to obtain lead titanium tellurate seed crystals by spontaneous crystallization.

[0030] c. Place the Pt crucible containing the mixed solution obtained in step a into a molten salt furnace. Fix the seed crystal obtained in step b onto the seed crystal rod using platinum wire, and place the seed crystal above the solution surface. First, preheat the seed crystal for 30-40 minutes. When the temperature is 5-15℃ higher than the saturation point, slowly immerse the seed crystal below the solution surface and hold it at that temperature for 5-20 minutes to remove impurities from the seed crystal surface. Then, reduce the temperature to the saturation point temperature at a cooling rate of 0.2-1℃ / min.

[0031] d. Then, slowly cool down at a rate of 1-5℃ / h, and grow the crystal by rotating the seed crystal rod at 3-60 rpm. After the crystal grows to the required size, lift the crystal to a position 1-2 cm above the liquid surface, and then cool down to room temperature at a rate of 10-50℃ / h. Finally, open the furnace and take out the crystal to obtain a second-order nonlinear optical crystal of lead titanium tellurate.

[0032] The molar ratio of PbO to PbF2 in the flux PbO-PbF2 system is 1-10:1-10; the molar ratio of PbO to TeO2 in the PbO-TeO2 system is 1-10:1-8; the molar ratio of TiF4 to PbO in the PbO-TiF4 system is 1-10:1-20; and the molar ratio of TeO2 to PbO to PbF2 in the TeO2-PbO-PbF2 system is 1-5:1-6:1-6.

[0033] The second-order nonlinear optical crystal of lead titanium tellurate obtained by the method described in this invention can be used to prepare frequency doubling devices. At room temperature, using an Nd:YAG Q-switched laser source, infrared light with a wavelength of 1064 nm is emitted. After passing through the target crystal, green laser light with a wavelength of 532 nm can be output. Attached Figure Description

[0034] Figure 1 Pb4Ti3TeO 13 Powder X-ray diffraction pattern of crystals.

[0035] Figure 2 Pb4Ti3TeO 13 The ultraviolet-visible-near-infrared diffuse reflectance spectrum of the crystal.

[0036] Figure 3 Pb4Ti3TeO 13 Infrared spectrum of crystals.

[0037] Figure 4 Typical Pb4Ti3TeO 13 A schematic diagram of the crystal's application, where 1 is the light source, 2 is the incident laser beam, and 3 is Pb4Ti3TeO. 13 4 is the crystal, 5 is the laser beam produced, and 6 is the filter. Detailed Implementation

[0038] To better illustrate the present invention, the following description is provided in conjunction with embodiments. However, the scope of protection of the present invention is not limited to the scope described in the embodiments.

[0039] Example 1:

[0040] Pb4Ti3TeO 13 The pure-phase synthesis reaction is as follows: 4PbO + 3TiO₂ + TeO₂ + 0.5O₂ → Pb₄Ti₃TeO 13

[0041] Analytical grade PbO, TiO2, and TeO2 raw materials were weighed, ground, and mixed evenly in a molar ratio of 4:3:1. The mixture was then transferred to a φ70mm×70mm Pt crucible and placed in a muffle furnace. The temperature was raised to 350℃ and held for 24 hours for pre-calcination to remove moisture and gases from the raw materials. Subsequently, the temperature was increased to 720℃ and calcined for at least 72 hours. Finally, heating was stopped, and the sample was allowed to cool to room temperature with the furnace to obtain a yellow powder, which is Pb4Ti3TeO. 13 Pure phase. The powder X-ray diffraction pattern of the sample was obtained using powder X-ray diffraction testing; see appendix. Figure 1 ;

[0042] The prepared compound, lead titanium tellurate (Pb₄Ti₃TeO), was... 13 Pure-phase polycrystalline powder and flux TeO2 were mixed at a molar ratio of 1:2 and thoroughly ground. The mixture was then placed in a φ70mm×70mm Pt crucible. The mixture was heated to approximately 800℃ at a heating rate of 50-80℃ / h to melt the raw materials and flux. The temperature was then maintained for 10-12 hours to ensure a uniform concentration of the high-temperature solution within the Pt crucible. Simultaneously, a platinum wire was slowly lowered below the solution surface, followed by cooling to induce spontaneous crystallization. The chemical formula of this crystal is Pb4Ti3TeO. 13 The compound has a UV cutoff edge of 403 nm and an infrared transmittance of 730 cm⁻¹. -1 There is no significant decrease in permeability, it has a wide permeability range, and its physicochemical properties are stable and it is not easily deliquescent. See Appendix. Figure 2 , 3.

[0043] The solution was slowly cooled at a rate of 1-5℃ / h to obtain lead titanium tellurate crystals.

[0044] Pb4Ti3TeO obtained by spontaneous crystallization 13 Small crystals are used as seed crystals to grow lead titanium tellurate crystals using Top Seed Granules (TSSG) technology. The seed crystal is fixed to a seed rod using platinum wire. First, the seed crystal is preheated by placing it 1-2 cm above the solution surface. Then, at a temperature 5-15°C above the saturation point, the seed crystal is slowly lowered into the solution and held for 30-40 minutes to remove surface impurities. Subsequently, the temperature is lowered to the saturation point.

[0045] Then, cool the crystal at a rate of 0.5-3℃ / day, with the seed crystal rod rotating at 5-60 rpm. After growth, lift the crystal to a height of 1-2 cm above the liquid surface and cool it to room temperature at a rate of 10-50℃ / h. Then remove the crystal to obtain Pb4Ti3TeO. 13 Crystal.

[0046] In the reaction formula, lead oxide can be replaced by other lead-containing salts such as lead fluoride, lead carbonate, lead hydroxide, lead chloride, or lead sulfate, and titanium oxide can be replaced by titanium fluoride, titanium hydroxide, or titanium chloride.

[0047] Example 2:

[0048] Pb4Ti3TeO 13 The pure-phase synthesis has the following reaction equation: 4PbF₂ + 3TiO₂ + TeO₂ + 2.5O₂ → Pb₄Ti₃TeO 13 +4F2↑

[0049] The prepared compound, lead titanium tellurate (Pb₄Ti₃TeO), was... 13 Pure-phase polycrystalline powder and flux PbO-PbF2 were mixed and ground uniformly in a molar ratio of 1:1, with the molar ratio of PbO to PbF2 being 1:2. The mixed sample was placed in a φ70mm×70mm Pt crucible, and the mixture was heated to 750-850℃ at a heating rate of 50-80℃ / h. After the mixture melted, it was held at this temperature for 10-12 hours to ensure a uniform concentration of the high-temperature solution in the Pt crucible. A platinum wire was then lowered below the surface of the solution, and the temperature was slowly lowered to induce spontaneous crystallization.

[0050] The solution was slowly cooled at a rate of 1-5℃ / h to obtain lead titanium tellurate crystals.

[0051] Pb4Ti3TeO obtained by spontaneous crystallization 13 The grain is used as a seed crystal for crystal growth. The seed crystal is fixed on the seed crystal rod using platinum wire. The seed crystal is first placed 1-2 cm above the liquid surface for preheating treatment. Then, at a temperature 5-15℃ above the saturation point, the seed crystal is slowly immersed below the liquid surface and kept for 30-40 minutes to remove surface impurities. Afterward, the temperature is lowered to the saturation point temperature.

[0052] The crystal is then cooled at a rate of 0.5-3℃ / day, with the crystal rotation speed at 25-30 rpm and automatic forward and reverse rotation. After crystal growth is complete, 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 to obtain Pb4Ti3TeO. 13 Crystal.

[0053] In the reaction formula, lead fluoride can be replaced by other lead-containing salts such as lead sulfide, lead carbonate, lead hydroxide, lead chloride, or lead sulfate, and titanium oxide can be replaced by titanium fluoride, titanium hydroxide, or titanium chloride.

[0054] Example 3:

[0055] Pb4Ti3TeO 13The pure-phase synthesis reaction is as follows: 4Pb(OH)₂ + 3TiO₂ + TeO₂ + 0.5O₂ → Pb₄Ti₃TeO 13 +4H2O↑

[0056] The prepared compound, lead titanium tellurate (Pb₄Ti₃TeO), was... 13 Pure-phase polycrystalline powder and flux PbO-TiF4 were mixed and ground uniformly at a molar ratio of 1:1, with a molar ratio of PbO to TiF4 of 2:1. The ground raw material mixture was placed in a φ70mm×70mm Pt crucible, and the mixture was heated to 750-850℃ at a heating rate of 50-80℃ / h. After the growth material and flux were completely melted, the temperature was maintained for 10-15 hours to ensure uniform concentration of the high-temperature solution in the Pt crucible. Platinum wire was immersed below the surface of the solution, and then the temperature was slowly lowered to allow spontaneous crystallization.

[0057] The solution was slowly cooled at a rate of 1-5℃ / h to obtain lead titanium tellurate crystals.

[0058] Pb4Ti3TeO obtained by spontaneous crystallization 13 The grain is used as a seed crystal for crystal growth. The seed crystal is fixed to the seed crystal rod using platinum wire. The seed crystal is first placed 1-2 cm above the liquid surface for preheating treatment. Then, at a temperature 5-15℃ higher than the saturation point, the seed crystal is slowly immersed below the liquid surface and held for 30-40 minutes to remove surface impurities. The temperature is then lowered to the saturation point temperature.

[0059] The liquid is then cooled at a rate of 0.5-3℃ / day, with the crystal rotating at 25-30 rpm and automatic forward and reverse rotation. After crystal growth is complete, 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 to obtain Pb4Ti3TeO. 13 Crystal.

[0060] In the reaction formula, lead hydroxide can be replaced by other lead-containing salts such as lead sulfide, lead carbonate, lead fluoride, lead chloride, or lead sulfate, and titanium oxide can be replaced by titanium fluoride, titanium hydroxide, or titanium chloride.

[0061] Example 4:

[0062] Pb4Ti3TeO 13 The pure-phase synthesis reaction is as follows: 4PbCl₂ + 3TiO₂ + TeO₂ + 2.5O₂ → Pb₄Ti₃TeO 13 +4Cl2↑

[0063] The prepared compound, lead titanium tellurate (Pb₄Ti₃TeO), was... 13Pure-phase polycrystalline powder and flux Li₂CO₃ are mixed at a molar ratio of 1:1 and ground uniformly. The ground raw material mixture is placed in a φ70mm×70mm Pt crucible, and the mixture is heated to 750-850℃ at a heating rate of 50-80℃ / h. After the crystal growth raw material and flux are completely melted, the temperature is maintained for 10-15h to ensure uniform concentration of the high-temperature solution in the Pt crucible. Platinum wire is immersed below the solution surface, and then the temperature is slowly lowered to allow spontaneous crystallization.

[0064] The solution was slowly cooled at a rate of 1-5℃ / h to obtain lead titanium tellurate crystals.

[0065] Pb4Ti3TeO obtained by spontaneous crystallization 13 The grain is used as a seed crystal for crystal growth. The seed crystal is fixed on the seed crystal rod using platinum wire. The seed crystal is first placed 1-2 cm above the liquid surface for preheating treatment. Then, at a temperature 5-15℃ above the saturation point, the seed crystal is slowly immersed below the liquid surface and kept for 30-40 minutes to remove surface impurities. After that, the temperature is lowered to the saturation point temperature.

[0066] The liquid is then cooled at a rate of 0.5-3℃ / day, with the crystal rotating at 25-30 rpm and automatic forward and reverse rotation. After crystal growth is complete, 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 to obtain Pb4Ti3TeO. 13 Crystal.

[0067] In the reaction formula, lead chloride can be replaced by other lead-containing salts such as lead sulfide, lead carbonate, lead fluoride, lead oxide, or lead sulfate, and titanium oxide can be replaced by titanium fluoride, titanium hydroxide, or titanium chloride.

[0068] Example 5:

[0069] Pb4Ti3TeO obtained by the above method 13 Crystal fabrication of nonlinear optical devices:

[0070] The Pb4Ti3TeO obtained in Examples 1-4 13 Nonlinear optical crystals are oriented and processed according to crystallographic data and the required thickness, angle, and size. The light-transmitting surface is then polished, and the crystal can be used as a nonlinear optical device.

[0071] According to the appendix Figure 4 The crystal is fixed at position 3. At room temperature, an infrared beam 2 with an incident wavelength of 1064 nm is incident on the crystal 3 using an Nd:YAG Q-switched laser source. The outgoing beam 4 contains infrared light with a wavelength of 1064 nm and green light with a wavelength of 532 nm. After passing through the filter 5, a green laser with a wavelength of 532 nm is obtained.

[0072] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and substitutions can be made without departing from the technical principles of the present invention, and these improvements and substitutions should also be considered within the scope of protection of the present invention.

Claims

1. This invention relates to a method for preparing a second-order nonlinear optical crystal, lead titanium tellurate, and the application of lead titanium tellurate single crystals grown using top-seeded crystal technology in nonlinear optical devices. The compound is synthesized via a high-temperature solid-state method, and its chemical formula is Pb₄Ti₃TeO. 13 .

2. The method for preparing the lead titanium tellurate nonlinear optical crystal according to claim 1, characterized in that: The pure-phase lead titanium tellurate and the nonlinear optical crystal were prepared by solid-state reaction method and flux method, respectively, including the following steps: a. The compound lead titanium tellurate (Pb₄Ti₃TeO) is prepared by mixing a lead-containing compound, a titanium-containing compound, and a tellurium-containing compound using a solid-state reaction method. 13 The molar ratio of lead in lead-containing compounds, titanium in titanium-containing compounds, and tellurium in tellurium-containing compounds is 4:3:

1. b. The compound titanium lead tellurate is synthesized by a high-temperature solid-state method. The specific process is as follows: lead-containing compound, titanium-containing compound and tellurium-containing compound raw materials are mixed and ground evenly using an agate mortar and pestle. The mixture is placed in a muffle furnace and pre-calcined at a low temperature to remove moisture and gas from the raw materials. The temperature is then slowly increased and calcined. The mixture is removed and ground multiple times during the process. Finally, it is cooled to room temperature, and the compound titanium lead tellurate is successfully synthesized. The lead-containing compound includes at least one of lead oxide, lead sulfide, lead hydroxide, or lead salts; the lead salts include at least one of lead fluoride, lead chloride, lead carbonate, and lead sulfate. The titanium-containing compound includes at least one of titanium oxide, titanium hydroxide, or titanium salt; the titanium salt includes at least one of titanium chloride and titanium fluoride; The tellurium-containing compound is tellurium dioxide; A mixture of any obtained lead titanium tellurate pure-phase polycrystalline powder or any obtained lead titanium tellurate single-phase polycrystalline powder with flux is heated to obtain a homogeneous mixed melt. Alternatively, a mixture of lead-containing compounds, titanium-containing compounds, and tellurium-containing compounds, or a mixture of lead-containing compounds, titanium-containing compounds, and tellurium-containing compounds with flux, can be directly heated and melted to obtain a homogeneous mixed melt. c. Place the Pt crucible containing the mixed solution prepared in step b into a molten salt furnace, and use platinum wire to fix the lead titanium tellurate seed crystal to one end of the seed crystal rod. First, preheat the seed crystal by placing it 1-2 cm above the liquid surface at a temperature 5°C above the saturation point. - At 15°C, the seed crystal is slowly immersed below the liquid surface and held for 30-40 minutes to melt away surface impurities or defects. Then, the temperature is lowered below the saturation temperature or kept at a constant temperature to obtain a lead titanium tellurate nonlinear optical crystal.

3. The method for preparing the lead titanium tellurate nonlinear optical crystal according to claim 2, characterized in that: The molar ratio of the pure-phase polycrystalline titanium lead tellurate powder to the flux is 1:0-20; the flux mainly includes PbO, PbF2, Li2CO3, TeO2, TiF4, and in addition, there are composite fluxes, including one or more of PbO-PbF2, TeO2-PbO, TiF4-PbO, or TeO2-PbO-PbF2.

4. The method for preparing the lead titanium tellurate nonlinear optical crystal according to claim 3, characterized in that: The molar ratio of PbO to PbF2 in the flux PbO-PbF2 system is 1-10:1-10; the molar ratio of PbO to TeO2 in the PbO-TeO2 system is 1-10:1-8; the molar ratio of TiF4 to PbO in the TiF4-PbO system is 1-10:1-20; and the molar ratio of TeO2 to PbO to PbF2 in the TeO2-PbO-PbF2 system is 1-5:1-6:1-6.

5. The use of the lead titanium tellurate nonlinear optical crystal according to claim 1, characterized in that: This lead titanium tellurate nonlinear optical crystal is used to fabricate frequency multipliers, up-frequency converters, down-frequency converters, and optical parametric oscillators.

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