Rare earth doped lutetium tantalum oxide single crystal and preparation method and application thereof
Rare-earth-doped lutetium tantalum oxide single crystals were prepared by laser heating base method and optical floating zone method, which solved the problem of high melting point material preparation and enabled the application of high-density scintillator material, suitable for electromagnetic calorimeter and radiation detection fields.
Patent Information
- Application Number
- CN202511188019.8
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-08-25
- Publication Date
- 2025-11-28
AI Technical Summary
Existing technologies are difficult to effectively prepare rare earth-doped lutetium tantalum oxide RexLu3-xTaO7 single crystals, mainly due to the difficulty in preparation caused by its high melting point, and the high requirements for crucibles in existing methods, which limit their application.
Rare-earth-doped lutetium tantalum oxide (RexLu3-xTaO7) single crystals were prepared using a laser-heated substrate method. This method, which combines laser heating substrate and optical floating zone method, avoids dependence on crucibles and allows for direct growth of single crystals from polycrystalline raw material rods.
High-density rare-earth-doped lutetium tantalum oxide single crystals were prepared with a density as high as 9.78 g/cm3. They are suitable for electromagnetic calorimeters, high-resolution radiation detection imaging, and radiation dose monitoring. They have good physicochemical stability and a high melting point, enabling them to work in harsh environments and improving detection efficiency.
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Figure CN121023644A_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of scintillator materials, and relates to a novel single crystal, its preparation method and application, and particularly to a rare earth-doped lutetium tantalum oxide single crystal, its preparation method and application. Background Technology
[0002] Rare earth-doped lutetium tantalum oxide Re x Lu 3-x TaO7 single crystal is a scintillator material that can convert the energy of high-energy particles (alpha particles, electrons, protons, neutrons, etc.) or radiation (gamma rays, X-rays) into ultraviolet / visible photons that are easily detected by photomultiplier tubes, silicon photodiodes, etc. It can be applied in electromagnetic calorimeters, high-resolution radiation detection imaging, and radiation dose monitoring. Since the main performance indicators of scintillators are high density, high light yield, and fast light decay, high-density scintillators have a large absorption coefficient and strong stopping power for high-energy rays or particles, resulting in a short radiation length. This allows them to convert as much radiation energy as possible into light signals within a very small scale, thereby improving detection efficiency. Rare-earth-doped lutetium tantalum oxide (Re...)... x Lu 3-x TaO7 crystals have a high density of 9.78 g / cm³. 3 This is far higher than the density of currently widely used scintillators, therefore Re x Lu 3-x TaO7 crystal is a promising new high-density scintillator material. However, Re... x Lu 3-x The melting point of TaO7 crystals is as high as 2380℃, which places high demands on the melting point and chemical stability of the crucible, leading to Re x Lu 3-x The preparation of TaO7 single crystals is difficult, therefore, current research on Re... x Lu 3-x There are few reports on the preparation and performance studies of TaO7 single crystals. Since the laser-heated substrate method and the optical floating zone method can prepare single crystals without a crucible and only require polycrystalline raw material rods, this invention employs the laser-heated substrate method to prepare high-melting-point Re x Lu 3-x The preparation of TaO7 single crystals will introduce a new type of high-density scintillator material to the field of scintillators. Summary of the Invention
[0003] To address the problems existing in the prior art, this invention provides a rare earth-doped lutetium tantalum oxide Re x Lu 3-x TaO7 single crystal, its preparation method and application: This single crystal can be applied to electromagnetic calorimeters, high-resolution radiation detection imaging and radiation dose monitoring.
[0004] To achieve the above object, the technical scheme of the present application is as follows: In the first aspect, a rare earth doped lutetium tantalum oxide single crystal is provided, and the chemical formula of the single crystal is Re x Lu 3-x TaO7, the Re is selected from one or more of rare earth elements (such as Eu, Tb, etc.), and the x satisfies 0≤x≤3.
[0005] Preferably, the lutetium tantalum oxide single crystal is cubic system, the melting point is 2380℃, and the density is 9.78g / cm 3 .
[0006] Preferably, the diameter of the single crystal is 200-1000μm, and the length of the single crystal is ≥1cm.
[0007] In the second aspect, a preparation method of the rare earth doped lutetium tantalum oxide single crystal is provided, which comprises selecting a seed crystal, preparing a rare earth doped lutetium tantalum oxide raw material rod, and growing the rare earth doped lutetium tantalum oxide single crystal by using a laser heating pedestal method or an optical floating zone method.
[0008] Preferably, the seed crystal is selected from an oxide single crystal with a melting point higher than that of the lutetium tantalum oxide single crystal or a melting point lower than that of the lutetium tantalum oxide single crystal by not more than 500℃, such as a sapphire single crystal, etc.
[0009] Preferably, the rare earth doped lutetium tantalum oxide raw material rod is prepared by the following steps: first, preparing a rare earth doped lutetium tantalum oxide polycrystal by batching, mixing, cold isostatic pressing and high-temperature solid phase reaction, and then cutting and calcining the polycrystal to obtain a pure quadrangular prism-shaped rare earth doped lutetium tantalum oxide raw material rod.
[0010] Preferably, when the laser heating pedestal method is used, the rare earth doped lutetium tantalum oxide raw material rod is melted by laser heating, and the laser power is 25-35W.
[0011] Preferably, when a seed crystal with a melting point lower than that of the rare earth doped lutetium tantalum oxide single crystal is used for single crystal growth, the following steps are included: (1) moving the raw material rod to the heating focal point, adjusting the laser power to 15-20W, and making the top end of the raw material rod locally melt and form a melt; (2) lowering the seed crystal to a first preset distance above the heating focal point, and the temperature at the preset position is lower than the melting point of the seed crystal to avoid melting thereof; (3) slowly moving the raw material rod upward, making the top end melt of the raw material rod contact the bottom end of the seed crystal, and under the premise of not melting the seed crystal, pulling the seed crystal upward at a speed of 0.5-1mm / min for 5-10s, so that a small section of rare earth doped lutetium tantalum oxide single crystal is grown at the bottom end of the seed crystal; (4) synchronously descending the seed crystal and the raw material rod at the same speed, and descending the bottom end of the seed crystal and the top end of the raw material rod to the heating focal point position; (5) increasing the laser power to 25-35W, adjusting the melting zone appearance to meet the single crystal continuous growth condition, and upwardly pulling the seed crystal and upwardly moving the raw material rod to continuously grow the rare earth doped lutetium tantalum oxide single crystal.
[0012] Preferably, during the growth of the rare earth doped lutetium tantalum oxide single crystal, the pulling speed of the single crystal is set to 0.2-0.4mm / min, and the ratio of the feeding speed of the rare earth doped lutetium tantalum oxide raw material rod to the pulling speed of the rare earth doped lutetium tantalum oxide single crystal is equal to the ratio of the cross-sectional area of the grown single crystal to the cross-sectional area of the rare earth doped lutetium tantalum oxide raw material rod.
[0013] Preferably, during the growth of the rare earth doped lutetium tantalum oxide single crystal to the required length, the pulling speed of the single crystal is set to 5-20mm / min to realize the separation of the single crystal from the melting zone.
[0014] The rare earth doped lutetium tantalum oxide single crystal Re x Lu 3-x TaO7 of the present application has a density of up to 9.78g / cm 3 , which is much higher than the density of the currently widely used scintillator, and is a very promising new type of high-density scintillator material, which can be applied in electromagnetic energy meters and / or high-resolution radiation detection imaging and / or irradiation dose monitoring.
[0015] The characteristics and advantages of the present application are as follows: (1) The present application uses the laser heating pedestal method to prepare the rare earth doped lutetium tantalum oxide Re x Lu 3-x TaO7 single crystal, the diameter of the single crystal is 200-1000μm, the length of the single crystal is ≥1cm, and the crystal surface is smooth and transparent, which is a new type of scintillator material with excellent performance.
[0016] (2) Compared with other materials, the rare earth doped lutetium tantalum oxide Re x Lu 3-x TaO7 single crystal of the present application has the following advantages: the density is up to 9.78g / cm 3 , which is much higher than the density of the currently widely used scintillator, the high-density scintillator has a large absorption coefficient for high-energy rays or particles and a strong stopping power, and can convert as much radiation energy as possible into light signals in a very small scale, thereby improving the detection efficiency; the physical and chemical properties are stable, and the melting point is as high as 2380℃, which can work in harsh environments such as high temperature and corrosive atmosphere. Therefore, the rare earth doped lutetium tantalum oxide of the present application has good application prospects in the fields of electromagnetic energy meters, high-resolution radiation detection imaging, and irradiation dose monitoring.
[0017] (3) The rare earth doped lutetium tantalum oxide Re x Lu 3-x TaO7 single crystal, avoids the limitation of the crucible method for growing crystals, and can be prepared into a single crystal by laser heating of a polycrystalline raw material rod without a crucible, solving the problem of high melting point of the rare earth doped lutetium tantalum oxide and difficult preparation. BRIEF DESCRIPTION OF DRAWINGS
[0018] Figure 1 Picture of the Lu3TaO7 single crystal sample prepared in Example 1; Figure 2 Laue diffraction spot diagram of the Lu3TaO7 single crystal prepared in Example 1; Figure 3 Excitation and emission spectra of the Lu3TaO7 single crystal prepared in Example 1; Figure 4 Eu 0.15 Lu 2.85 TaO7 single crystal sample picture; Figure 5 Eu 0.15 Lu 2.85 TaO7 single crystal Laue diffraction spot diagram; Figure 6 Eu 0.15 Lu 2.85 TaO7 single crystal emission spectrum at an excitation wavelength of 285 nm; Figure 7 Eu 0.15 Lu 2.85 TaO7 single crystal fluorescence lifetime curve at an excitation wavelength of 285 nm and an emission wavelength of 629 nm; Figure 8 Bi 0.03 Lu 2.97 TaO7 single crystal sample picture; Figure 9 Tb 0.03 Lu 2.97 TaO7 single crystal sample picture. DETAILED DESCRIPTION
[0019] The application will be further described below in conjunction with examples, but is not limited thereto.
[0020] Example 1 The Lu3TaO7 single crystal is prepared by a laser heating pedestal method, and the preparation method is as follows: (a) Seed crystal selection Since Lu3TaO7 single crystal is a new material, there is no readily available Lu3TaO7 single crystal as a seed crystal. Therefore, a single crystal with a melting point similar to that of Lu3TaO7 is selected as the seed crystal. In this embodiment, a sapphire single crystal with a diameter of 450μm is selected as the seed crystal.
[0021] (b) Preparation of Lu3TaO7 polycrystalline raw material rods According to the stoichiometric ratio of Lu2O3:Ta2O5=3:1, 30g of high-purity Lu2O3 and Ta2O5 oxide powder raw materials were calculated and weighed. The raw materials were placed in a bottle and shaken for 24 hours to ensure thorough mixing. The mixed raw materials were then packed into a cylindrical, slender rubber sleeve and compacted. The rubber sleeve containing the raw materials was then subjected to cold isostatic pressing. Afterward, the cylindrical raw material rod was disassembled and placed in a muffle furnace for a high-temperature solid-state reaction at 1500℃ to obtain Lu3TaO7 polycrystalline material. The cylindrical polycrystalline raw material rod was then cut into 1×1×80mm square rods. Finally, the cut raw material rods were calcined at 800℃ to remove impurities, thus obtaining pure square prism-shaped Lu3TaO7 polycrystalline raw material rods.
[0022] (c) Melting of Lu3TaO7 polycrystalline feed rod The top of a quadrangular prism-shaped Lu3TaO7 polycrystalline raw material rod is placed in the laser heating area of the laser heating base crystal growth system. The position of the raw material rod is adjusted so that its top coincides with the focused laser. Then, the laser power is adjusted to 30W to melt the top of the raw material rod into a hemispherical shape.
[0023] (d) Single crystal growth of Lu3TaO7 Since the melting point of the seed sapphire single crystal is lower than that of the Lu3TaO7 single crystal, the laser power needs to be reduced, slowly decreasing to 15W to locally melt the tip of the raw material rod. Then, the seed crystal is lowered to a low-temperature region above the laser focal point to prevent melting. Next, the raw material rod is moved upwards so that the melt at its tip contacts the seed crystal. While ensuring the seed crystal does not melt, the seed crystal is pulled upwards at a speed of 0.5mm / min for 5 seconds to grow a small section of Lu3TaO7 single crystal. Then, the seed crystal and raw material rod are simultaneously lowered at a speed of 1mm / min until the tip of the raw material rod is at the center of the laser focal point. The laser power is then increased to 32W, and the morphology of the molten zone is adjusted until the conditions for continuous single crystal growth are met. During growth, the pulling speed is set to 0.3mm / min, and the target diameter is 400μm. When the diameter of the grown single crystal stabilizes, the laser power and single crystal pulling speed are kept constant. The ratio of the feed rate to the single crystal pulling speed is equal to the ratio of the cross-sectional area of the grown single crystal to the cross-sectional area of the raw material rod. PID control of the feed rate is then activated for automated single crystal growth.
[0024] (e)Lu3TaO7 single crystal melting and desorption Set the pulling speed to 10 mm / min to allow the single crystal to detach from the molten zone, and slowly reduce the laser power to 0 W.
[0025] The obtained Lu3TaO7 single crystal sample is as follows Figure 1 As shown, the single crystal is transparent and crack-free, and the Laue diffraction pattern is as follows ( Figure 2 The sample exhibits clear and bright Laue diffraction spots, indicating that it is a single-crystal structure. The excitation and emission spectra (excitation wavelength 350 nm, emission wavelength 430 nm) are as follows: Figure 3 As shown, the excitation spectrum is mainly distributed in the 300~400 nm band, indicating that Lu3TaO7 has good absorption ability for near-ultraviolet light. The emission spectrum is in the 400~550 nm band, showing a wide band emission characteristic.
[0026] Example 2 Eu 0.15 Lu 2.85 TaO7 single crystals were prepared by laser heating substrate method, as follows: (a) Seed crystal selection Since Lu3TaO7 single crystals have already been prepared in Example 1, the Lu3TaO7 single crystals in Example 1 are selected as seed crystals.
[0027] (b)Eu 0.15 Lu 2.85 Preparation of TaO7 polycrystalline raw material rods Based on the stoichiometric ratio of Eu₂O₃:Lu₂O₃:Ta₂O₅ = 0.15:2.85:1, the corresponding masses of high-purity oxide powders of Eu₂O₃, Lu₂O₃, and Ta₂O₅ were calculated and weighed. The raw materials were placed in a bottle and shaken for 24 hours to ensure thorough mixing. The mixed raw materials were then packed into a cylindrical, slender rubber sleeve and compacted. The rubber sleeve containing the raw materials was then subjected to cold isostatic pressing. Afterward, the cylindrical raw material rod was disassembled and placed in a muffle furnace for a high-temperature solid-state reaction at 1500℃ to obtain Eu₂O₃. 0.15 Lu 2.85 TaO7 polycrystalline material is obtained by cutting the columnar polycrystalline raw material rod into 1×1×80mm square rods, and finally calcining the cut raw material rods at 800℃ to remove impurities, thus obtaining pure tetragonal prism-shaped Eu. 0.15 Lu 2.85 TaO7 polycrystalline raw material rods.
[0028] (c)Eu 0.15 Lu 2.85 TaO7 polycrystalline raw material rod melting The quadrangular prism Eu 0.15 Lu 2.85The top of the TaO7 polycrystalline raw material rod is placed in the laser heating area of the laser heating base crystal growth system. The position of the raw material rod is adjusted so that its top coincides with the focused laser. Then, the laser power is adjusted to 28W to melt the top of the raw material rod into a hemispherical shape.
[0029] (d)Eu 0.15 Lu 2.85 TaO7 single crystal growth The seed crystal is slowly lowered until it contacts the tip of the molten raw material rod, and then pulled upwards at a speed of 0.3 mm / min to grow Eu. 0.15 Lu 2.85 TaO7 single crystal, with a target diameter of 400 μm. Once the crystal diameter stabilizes, the laser power and crystal pulling speed remain constant. The ratio of the feed rate to the crystal pulling speed is equal to the ratio of the cross-sectional area of the grown single crystal to the cross-sectional area of the raw material rod. PID control of the feed rate is then initiated, and Eu... 0.15 Lu 2.85 Automated growth of TaO7 single crystals.
[0030] (e)Eu 0.15 Lu 2.85 TaO7 single crystal melting When Eu 0.15 Lu 2.85 When the TaO7 single crystal grows to the required length, the single crystal growth rate is set to 10 mm / min to allow the single crystal to leave the molten zone, and the laser power is slowly reduced to 0 W.
[0031] Eu produced 0.15 Lu 2.85 TaO7 single crystal samples, such as Figure 4 As shown, the single crystal is transparent and longer than 6 cm. Its Laue diffraction pattern is as follows. Figure 5 As shown, clear and bright Laue diffraction spots indicate that the sample has a single-crystal structure. The emission spectrum at an excitation wavelength of 285 nm is as follows. Figure 6 As shown, the fluorescence lifetime curves at an excitation wavelength of 285 nm and an emission wavelength of 629 nm are as follows: Figure 7 As shown, it exhibits a single exponential decay (τ=1.43 ms).
[0032] Example 3 Bi 0.03 Lu 2.97 TaO7 single crystals were prepared by laser heating substrate method, as follows: (a) Seed crystal selection The Lu3TaO7 single crystal from Example 1 was selected as the seed crystal.
[0033] (b)Bi 0.03 Lu 2.97Preparation of TaO7 polycrystalline raw material rods Based on the stoichiometric ratio of Bi₂O₃:Lu₂O₃:Ta₂O₅ = 0.03:2.97:1, the corresponding masses of high-purity Bi₂O₃, Lu₂O₃, and Ta₂O₅ oxide powder raw materials were calculated and weighed. The raw materials were placed in a bottle and shaken for 24 hours to ensure thorough mixing. The mixed raw materials were then packed into a cylindrical, slender rubber sleeve and compacted. The rubber sleeve containing the raw materials was then subjected to cold isostatic pressing. Finally, the cylindrical raw material rod was disassembled and placed in a muffle furnace for a high-temperature solid-state reaction at 1500℃ to obtain Bi₂O₃. 0.03 Lu 2.97 TaO7 polycrystalline material is obtained by cutting the columnar polycrystalline raw material rod into 1×1×80mm square rods, and finally calcining the cut raw material rods at 800℃ to remove impurities, thus obtaining pure tetragonal prism-shaped Bi. 0.03 Lu 2.97 TaO7 polycrystalline raw material rods.
[0034] (c)Bi 0.03 Lu 2.97 TaO7 polycrystalline raw material rod melting The quadrangular prism Bi 0.03 Lu 2.97 The top of the TaO7 polycrystalline raw material rod is placed in the laser heating area of the laser heating base crystal growth system. The position of the raw material rod is adjusted so that its top coincides with the focused laser. Then, the laser power is adjusted to 30W to melt the top of the raw material rod into a hemispherical shape.
[0035] (d)Bi 0.03 Lu 2.97 TaO7 single crystal growth The seed crystal is slowly lowered until it contacts the tip of the molten raw material rod, and then pulled upwards at a speed of 0.3 mm / min to grow Bi. 0.03 Lu 2.97 TaO7 single crystal, with a target diameter of 400 μm. Once the crystal diameter stabilizes, the laser power and crystal pulling speed remain constant. The ratio of the feed rate to the crystal pulling speed is equal to the ratio of the cross-sectional area of the grown single crystal to the cross-sectional area of the raw material rod. PID control of the feed rate is then initiated, and Bi... 0.03 Lu 2.97 Automated growth of TaO7 single crystals.
[0036] (e)Bi 0.03 Lu 2.97 TaO7 single crystal melting When Bi 0.03 Lu 2.97 When the TaO7 single crystal grows to the required length, the single crystal growth rate is set to 10 mm / min to allow the single crystal to leave the molten zone, and the laser power is slowly reduced to 0 W.
[0037] Bi produced 0.03 Lu 2.97 TaO7 single crystal samples, such as Figure 8 As shown, it is a single transparent crystal with a length of approximately 5.4 cm.
[0038] Example 4 Tb 0.03 Lu 2.97 TaO7 single crystals were prepared by laser heating substrate method, as follows: (a) Seed crystal selection The Lu3TaO7 single crystal from Example 1 was selected as the seed crystal.
[0039] (b)Tb 0.03 Lu 2.97 Preparation of TaO7 polycrystalline raw material rods Based on the stoichiometric ratio of Tb₂O₃:Lu₂O₃:Ta₂O₅ = 0.03:2.97:1, the corresponding masses of high-purity Tb₂O₃, Lu₂O₃, and Ta₂O₅ oxide powder raw materials were calculated and weighed. The raw materials were placed in a bottle and shaken for 24 hours to ensure thorough mixing. The mixed raw materials were then packed into a cylindrical, slender rubber sleeve and compacted. The rubber sleeve containing the raw materials was then subjected to cold isostatic pressing. Afterward, the cylindrical raw material rod was disassembled and placed in a muffle furnace for a high-temperature solid-state reaction at 1500℃ to obtain Tb₂O₃. 0.03 Lu 2.97 TaO7 polycrystalline material is obtained by cutting the columnar polycrystalline raw material rod into 1×1×80mm square rods, and finally calcining the cut raw material rods at 800℃ to remove impurities, thus obtaining pure square prism-shaped Tb. 0.03 Lu 2.97 TaO7 polycrystalline raw material rods.
[0040] (c)Tb 0.03 Lu 2.97 TaO7 polycrystalline raw material rod melting The quadrangular prism Tb 0.03 Lu 2.97 The top of the TaO7 polycrystalline raw material rod is placed in the laser heating area of the laser heating base crystal growth system. The position of the raw material rod is adjusted so that its top coincides with the focused laser. Then, the laser power is adjusted to 30W to melt the top of the raw material rod into a hemispherical shape.
[0041] (d)Tb 0.03 Lu 2.97 TaO7 single crystal growth The seed crystal is slowly lowered until it contacts the tip of the molten raw material rod, and then pulled upwards at a speed of 0.3 mm / min to grow Tb. 0.03 Lu 2.97TaO7 single crystal, with a target diameter of 400 μm. Once the crystal diameter stabilizes, the laser power and crystal pulling speed remain constant. The ratio of the feed rate to the crystal pulling speed is equal to the ratio of the cross-sectional area of the grown single crystal to the cross-sectional area of the raw material rod. PID control of the feed rate is then activated to perform Tb... 0.03 Lu 2.97 Automated growth of TaO7 single crystals.
[0042] (e)Tb 0.03 Lu 2.97 TaO7 single crystal melting When Tb 0.03 Lu 2.97 When the TaO7 single crystal grows to the required length, the single crystal growth rate is set to 10 mm / min to allow the single crystal to leave the molten zone, and the laser power is slowly reduced to 0 W.
[0043] Tb produced 0.03 Lu 2.97 TaO7 single crystal samples, such as Figure 9 As shown, the single crystal is brown and longer than 2 cm.
[0044] Other embodiments of this application will readily occur to those skilled in the art upon consideration of the specification and practice of the disclosure herein. This application is intended to cover any variations, uses, or adaptations of this application that follow the general principles of this application and include common knowledge or customary techniques in the art not disclosed herein. The specification and embodiments are to be considered exemplary only.
Claims
1. A rare earth-doped lutetium-tantalum oxide single crystal, characterized in that, The chemical formula of this single crystal is Re. x Lu 3-x TaO7, wherein Re is selected from one or more rare earth elements, and x satisfies 0≤x≤3.
2. The rare-earth-doped lutetium tantalum oxide single crystal according to claim 1, characterized in that, The lutetium tantalum oxide single crystal is cubic, with a melting point of 2380℃ and a density of 9.78 g / cm³. 3 .
3. The rare-earth-doped lutetium tantalum oxide single crystal according to claim 1, characterized in that, The diameter of the single crystal is 200~1000μm, and the length of the single crystal is ≥1cm.
4. A method for preparing a rare-earth-doped lutetium tantalum oxide single crystal according to any one of claims 1 to 3, characterized in that, Seed crystals were selected to prepare rare earth-doped lutetium tantalum oxide raw material rods, and rare earth-doped lutetium tantalum oxide single crystals were grown using the laser heating substrate method or the optical floating zone method.
5. The method for preparing rare-earth-doped lutetium tantalum oxide single crystals according to claim 4, characterized in that, In the selection of seed crystals, oxide single crystals with melting points higher than lutetium tantalum oxide single crystals or melting points lower than lutetium tantalum oxide single crystals not exceeding 500℃ are selected as seed crystals.
6. The method for preparing rare-earth-doped lutetium tantalum oxide single crystals according to claim 4, characterized in that, Rare earth-doped lutetium tantalum oxide raw material rods are prepared through the following steps: First, rare earth-doped lutetium tantalum oxide polycrystalline material is prepared by batching, mixing, cold isostatic pressing and high-temperature solid-state reaction. Then, the polycrystalline material is cut and calcined to obtain pure rare earth-doped lutetium tantalum oxide raw material rods. When using the laser heating base method, the laser power is set to 25~35W.
7. The method for preparing rare-earth-doped lutetium tantalum oxide single crystals according to claim 5, characterized in that, When the method uses a seed crystal with a melting point lower than that of the rare earth-doped lutetium tantalum oxide single crystal for single crystal growth, it includes the following steps: (1) Move the raw material rod to the heating focal point and adjust the laser power to 15~20W so that the top of the raw material rod is partially melted and forms a melt; (2) The seed crystal is lowered to a first preset distance above the heating focal point, where the temperature is lower than the melting point of the seed crystal to prevent it from melting; (3) Slowly move the raw material rod upward so that the melt at the top of the rod contacts the bottom of the seed crystal. Without melting the seed crystal, pull the seed crystal upward at a speed of 0.5~1mm / min for 5~10s so that a small section of rare earth doped lutetium tantalum oxide single crystal grows at the bottom of the seed crystal. (4) The seed crystal and the raw material rod are lowered synchronously at the same speed, so that the bottom of the seed crystal and the top of the raw material rod are lowered to the position of the heating focus; (5) Increase the laser power to 25~35W and adjust the morphology of the melting zone to meet the conditions for continuous growth of single crystal. Pull the seed crystal upward and move the raw material rod upward to continuously grow rare earth doped lutetium tantalum oxide single crystal.
8. The method for preparing rare-earth-doped lutetium tantalum oxide single crystals according to claim 4, characterized in that, When growing rare-earth-doped lutetium tantalum oxide single crystals, the pulling speed of the single crystal is set to 0.2~0.4 mm / min, and the ratio of the feeding speed of the rare-earth-doped lutetium tantalum oxide raw material rod to the pulling speed of the rare-earth-doped lutetium tantalum oxide single crystal is controlled to be equal to the ratio of the cross-sectional area of the grown single crystal to the cross-sectional area of the rare-earth-doped lutetium tantalum oxide raw material rod.
9. The method for preparing rare-earth-doped lutetium tantalum oxide single crystals according to claim 4, characterized in that, When rare earth-doped lutetium tantalum oxide single crystals are grown to the required length, the single crystal pulling speed is set to 5~20 mm / min to achieve single crystal detachment from the molten zone.
10. The application of the rare earth-doped lutetium tantalum oxide single crystal according to any one of claims 1 to 3 or the single crystal prepared by the preparation method according to any one of claims 4 to 9 in electromagnetic calorimeters and / or high-resolution radiation detection imaging and / or radiation dose monitoring.