Millimeter-sized thorium cluster compound single crystal, synthesis method thereof and application thereof in radiation detection and protection

Abstract

The application discloses a millimeter-level thorium cluster compound single crystal, a synthesis method thereof and application of the millimeter-level thorium cluster compound single crystal in radiation detection and protection, and relates to the technical field of radiation detection and protection. The synthesis method comprises the following process: a hydrophilic thorium salt and 3-pyridine-4-yl-benzoic acid are subjected to a solvothermal reaction in a mixed solvent, and after the reaction is completed, a transparent block crystal is obtained; the transparent block crystal is washed and dried to obtain the millimeter-level thorium cluster compound single crystal; the mixed solvent comprises water, an inorganic acid and an organic solvent. The millimeter-level thorium cluster compound single crystal has the effects of radiation color change, good ray response selectivity, strong radiation stability, strong ray retardation capacity and high reusability. The thorium metal cluster compound single crystal material can be used for detecting X-ray cumulative radiation dose by using the above-mentioned properties, and simultaneously acts as a radiation shielding material to efficiently block ionizing radiation, thereby playing a role in radiation protection.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of radiation detection materials, in particular to a millimeter-level thorium cluster single crystal and a synthesis method thereof and application thereof in radiation detection and protection. BACKGROUND

[0002] With the rapid development of the fields of national defense industry, nuclear science and technology, radiation medicine, radiation technology has been widely used in medical diagnosis, food processing, national defense equipment, etc. The harm of the generated rays to the environment and human beings has also initially appeared. Developing efficient, sensitive and fast ionizing radiation detection technology is the key to radiation pollution prevention, and designing efficient radiation shielding materials has become an important guarantee for the rational use of radiation technology. However, the traditional radiation shielding materials are difficult to meet the requirements of structure and function integration, and the materials with both radiation detection and radiation shielding functions are even rarer.

[0003] At present, a variety of commercial chemical dosimeter materials have been developed, such as radiation photoluminescence dosimeter, scintillator dosimeter, thermoluminescence dosimeter, alanine dosimeter, etc. Radiation color-changing materials are also one of the dosimeter materials, but there are still defects such as poor sensitivity, narrow detection line and poor stability. The traditional irradiation dosimeter materials have defects such as poor radiation blocking ability and narrow detection line range, which leads to that some materials can only realize qualitative or semi-quantitative detection of radiation dose. The traditional radiation shielding materials are generally lead materials with high density and large atomic number, but considering the toxicity of lead compounds and the generation of secondary radiation, concrete or fiber fabric is generally used to protect X / γ rays and other ionizing radiation. However, with the further development of nuclear industry and radiation devices, the field of nuclear energy application is becoming more and more wide, and simple radiation shielding materials cannot meet the requirements of radiation detection and protection. Therefore, it is necessary to develop new radiation detection and protection materials.

[0004] Actinide metals have the advantages of large atomic number, high density and strong radiation blocking ability, and some research institutions have carried out related research on actinide metals as radiation detection materials. However, there are few materials that have both radiation shielding and dosimeter functions. Such materials can not only qualitatively or quantitatively detect radiation dose through irradiation color change, but also can shield radiation. Therefore, the development of such materials can help to solve the problem of single function of materials in the field of dosimeter and radiation shielding materials. SUMMARY

[0005] In order to solve the technical problems existing in the prior art, the purpose of the present application is to provide a millimeter-level thorium cluster single crystal and a synthesis method thereof and application thereof in radiation detection and protection, which can solve the problem of single function of materials in the field of dosimeter and radiation shielding materials.

[0006] The technical scheme adopted by the present application is as follows:

[0007] A synthesis method of a millimeter-level thorium cluster single crystal comprises the following processes:

[0008] A water-soluble thorium salt and 3-pyridine-4-yl-benzoic acid are subjected to a solvothermal reaction in a mixed solvent, and after the reaction is completed, transparent block crystals are obtained, which are washed and dried to obtain the millimeter-level thorium cluster single crystal.

[0009] The mixed solvent comprises water, an inorganic acid and an organic solvent.

[0010] Preferably, the inorganic acid is perchloric acid, and the mass content of the perchloric acid in the mixed solvent is 4%-5%, and the pH value of the solvothermal reaction system is not greater than 1.5.

[0011] Preferably, the organic solvent is N,N'-dimethylformamide, and the volume ratio of water to N,N'-dimethylformamide is (3-5):1.

[0012] Preferably, the molar ratio of the water-soluble thorium salt to 3-pyridine-4-yl-benzoic acid is (1-2):(1:2).

[0013] Preferably, in the solvothermal reaction system, the concentration of the water-soluble thorium salt is 0.02-0.10 mmol / mL.

[0014] Preferably, the water-soluble thorium salt is thorium nitrate.

[0015] Preferably, in the solvothermal reaction process, the reaction temperature is 90-120 DEG C, and the reaction time is 5-10 days.

[0016] The present application also provides a millimeter-level thorium cluster single crystal, which is prepared by the synthesis method as described above, and has the following chemical formula:

[0017] [Th6O4(OH)4(H2O)6](H8C 12 NO2)6(COOH)6.

[0018] The metal center of the millimeter-level thorium cluster single crystal is tetravalent thorium element, and the ligand is 3-pyridine-4-yl-benzoic acid.

[0019] The millimeter-level thorium cluster single crystal can produce irradiation discoloration under irradiation, and can restore the color before irradiation after the irradiation discoloration.

[0020] The millimeter-level thorium cluster single crystal as described above is used for X-ray cumulative dose detection.

[0021] The millimeter-scale thorium cluster single crystal described above is used as a radiation shielding material in radiation protection.

[0022] The present invention has the following beneficial effects:

[0023] In the synthesis method of millimeter-scale thorium cluster single crystals of this invention, the role of the inorganic acid is to adjust the reaction pH to below 1.5 and to maintain the crystal structure framework. Water is used to dissolve the thorium salt, and the organic solvent is used to dissolve 3-pyridin-4-yl-phenylcarboxylic acid. This invention uses 3-pyridin-4-yl-phenylcarboxylic acid as a ligand, which coordinates with tetravalent thorium under solvothermal conditions to crystallize, resulting in the millimeter-scale thorium cluster single crystals exhibiting irradiation discoloration under X-ray irradiation.

[0024] The millimeter-scale thorium cluster single crystal of the present invention has a radiation-induced color-changing effect and good X-ray response selectivity, strong radiation stability, strong X-ray blocking ability, and high reusability. Utilizing the above properties, the thorium metal cluster single crystal material of the present invention can be used to detect the cumulative X-ray radiation dose, and at the same time, it can act as a radiation shielding material to effectively block ionizing radiation and play a role in radiation protection.

[0025] The above description is merely an overview of the technical solution of the present invention. In order to better understand the technical means of the present invention and to implement it in accordance with the contents of the specification, the following describes the preferred embodiments of the present invention in conjunction with detailed drawings. Attached Figure Description

[0026] Figure 1 This is a schematic diagram of the structure of the millimeter-scale thorium cluster single crystal prepared in Example 1 of the present invention;

[0027] Figure 2 These are powder diffraction patterns of the millimeter-scale thorium cluster single crystal before and after irradiation, as tested in Example 1 of this invention.

[0028] Figure 3 These are the infrared spectra of 3-pyridin-4-yl-phenylcarboxylic acid and millimeter-scale thorium cluster single crystals before and after irradiation, as tested in Example 1 of this invention.

[0029] Figure 4 This is a thermal stability diagram of the millimeter-scale thorium cluster single crystal tested in Example 1 of this invention;

[0030] Figure 5 This is an irradiated reversible color-changing photograph of a millimeter-scale thorium cluster single crystal tested in Example 1 of this invention;

[0031] Figure 6(a) shows the UV-vis absorption spectra of the millimeter-sized thorium cluster single crystal before and after X-ray irradiation, as tested in Example 1 of the present invention; Figure 6(b) shows the UV-vis absorption spectra of the millimeter-sized thorium cluster single crystal before and after UV irradiation, as tested in Example 1 of the present invention.

[0032] Figure 7 This is a graph showing the free radical signal before and after irradiation with different doses of X-rays and before and after UV irradiation fading of a millimeter-sized thorium cluster single crystal in Example 1 of the present invention.

[0033] Figure 8 These are color change images of the millimeter-sized thorium cluster single crystal tested under different doses of X-ray irradiation in Example 1 of this invention;

[0034] Figure 9 This is a linear fit graph between the absorption peak intensity at 372 nm and the cumulative X-ray dose in the absorption spectrum test of the millimeter-scale thorium cluster single crystal of Example 1 of the present invention after X-ray irradiation.

[0035] Figure 10(a) is a schematic diagram of the size of the single crystal tested in Example 1 of the present invention, which is a millimeter-sized thorium cluster compound; Figure 10(b) is a diagram of the longitudinal discoloration depth of the irradiated surface of the single crystal of the millimeter-sized thorium cluster compound in Example 1 of the present invention after irradiation with 5 kGy X-rays.

[0036] Figure 11(a) is a diagram showing the dimensions of a wafer made from a millimeter-sized thorium cluster single crystal according to Example 1 of the present invention; Figure 11(b) is a diagram showing an X-ray radiation shielding test device made from a millimeter-sized thorium cluster single crystal according to Example 1 of the present invention.

[0037] Figure 12(a) shows the X-ray energy spectrum measured by a scintillator detector before and after the X-ray blocking window of the millimeter-sized thorium cluster single crystal sample with different thicknesses in Example 1 of the present invention; Figure 12(b) shows the photon count rate measured before and after the X-ray blocking window of the millimeter-sized thorium cluster single crystal sample with different thicknesses in Example 1 of the present invention. Detailed Implementation

[0038] The specific embodiments of the present invention will be described in further detail below with reference to the accompanying drawings and examples. The following examples are for illustrative purposes only and are not intended to limit the scope of the invention.

[0039] The present invention provides a method for synthesizing millimeter-scale thorium cluster single crystals, comprising the following steps:

[0040] A water-soluble thorium salt and 3-pyridin-4-yl-phenylcarboxylic acid are subjected to a solvothermal reaction in a mixed solvent of water and organic solvent at a reaction temperature of 90-120℃. After the reaction is complete, transparent bulk crystals are obtained, which include thorium metal cluster single crystal materials. The mixed solvent also includes 4wt%-5wt% inorganic acid, and the molar ratio of water-soluble thorium salt to 3-pyridin-4-yl-phenylcarboxylic acid is (1-2):(1:2).

[0041] Furthermore, the water-soluble thorium salt is thorium nitrate.

[0042] Furthermore, in the solvothermal reaction system, the concentration of water-soluble thorium salt is 0.02-0.10 mmol / mL.

[0043] Furthermore, the volume ratio of water to organic solvent is (3-5):1.

[0044] Furthermore, the organic solvent is selected from N,N'-dimethylformamide (DMF).

[0045] Furthermore, the solvothermal reaction time is 5-10 days.

[0046] In this invention, 4.5 wt% inorganic acid means that the inorganic acid accounts for 4%-5% of the total mass of the reaction solution.

[0047] In the above synthesis methods, the role of the inorganic acid is to adjust the reaction pH and crystal structure framework. The concentration of the inorganic acid refers to the mass fraction of the inorganic acid in the mixed solvent. The pH of the solvothermal reaction system is not greater than 1.5. The role of water is to dissolve the thorium salt, and the role of the organic solvent is to dissolve 3-pyridin-4-yl-phenylcarboxylic acid.

[0048] The chemical formula of the millimeter-sized thorium cluster single crystal obtained by the above synthesis method of the present invention is as follows:

[0049] [Th6O4(OH)4(H2O)6](H8C 12 NO2)6(COOH)6

[0050] The metal center of this millimeter-scale thorium cluster single crystal is tetravalent thorium, and the ligand is 3-pyridin-4-yl-phenylcarboxylic acid.

[0051] The present invention relates to the application of millimeter-scale thorium cluster single crystals in X-ray cumulative dose detection; the irradiation source includes X-rays.

[0052] Furthermore, the X-ray tube target material is a W target, and the output power of the X-ray tube is 11.5-12.5W.

[0053] Furthermore, the quantitative detection dose of X-rays is no more than 4 kGy.

[0054] The millimeter-scale thorium cluster single crystal of this invention exhibits a color change under X-ray irradiation; this characteristic is known as irradiation-induced color change. Utilizing this characteristic, it can be used for X-ray cumulative dose detection, enabling quantitative analysis of X-ray dose. The dose detection method includes establishing detection standards and the detection procedure itself.

[0055] The steps to establish detection standards include using an X-ray source with known voltage and current and dose rate, and establishing detection standards based on the color change of millimeter-scale thorium cluster single crystals or the change of absorption spectral signals before and after irradiation.

[0056] The detection steps include irradiating the millimeter-sized thorium cluster single crystal of the present invention with X-rays of unknown intensity, comparing the color change of the thorium cluster single crystal material or the change of the absorption spectrum signal before and after irradiation with the detection standard, and performing quantitative or qualitative analysis on the X-rays of unknown intensity.

[0057] Furthermore, when establishing testing standards, quantitative or qualitative testing standards should be established.

[0058] When establishing quantitative detection standards, this includes establishing quantitative detection standards for changes in absorption spectra.

[0059] When establishing a quantitative detection standard for the intensity change of characteristic peaks in absorption spectra, the original thorium cluster single crystal material is irradiated under X-rays of known intensity, and then the absorption spectrum of the thorium cluster single crystal material is recorded. The relationship between the cumulative X-ray irradiation dose and the intensity change of characteristic peaks in absorption spectra is established, and this is used as the detection standard.

[0060] The recording method can be achieved using a UV-vis absorption spectroscopy acquisition system.

[0061] When establishing a visual qualitative detection method for color change caused by irradiation, the original thorium cluster compound single crystal material is irradiated with X-rays of unknown intensity. The color change produced is observed with the naked eye and compared with the initial color of the material. The cumulative dose of the X-ray source of known intensity corresponding to the occurrence of the same color change is found, thereby determining the dose number of the X-ray source to be tested.

[0062] Furthermore, for quantitative detection, the X-ray detection dose is 1.2-4 kGy, and for qualitative detection, the X-ray detection dose is 0-4.8 kGy.

[0063] Furthermore, when collecting the changes in UV-vis absorption spectrum signals after X-ray irradiation, the method also includes collecting signals from thorium cluster single crystal materials under white light using a solid-state spectrometer.

[0064] After the thorium cluster compound single crystal material of the present invention exhibits irradiation discoloration behavior, it can be heated at 90-120°C for 5-10 days in an indoor environment with normal temperature (e.g., 20-35°C) and normal pressure (e.g., 101-103 kPa) and irradiated under ultraviolet light for 1-2 days, and the material color can be completely restored to the state before irradiation, so that the material can be recycled during the irradiation detection process.

[0065] Furthermore, after irradiation, the material can be placed in a dark room at room temperature and pressure for 2-3 months, after which the material will return from deep purple to colorless. Because irradiation excites the organic ligands to generate free radicals, the free radical signal generated after irradiation can be analyzed using electron paramagnetic resonance (EPR) spectroscopy. The free electrons are transferred within the pyridine ring of the ligand, and the enhanced π-π interactions in the structure lead to luminescence and a change in the material's color. After resting in the dark room, the free radical signal disappears, and the material's color returns to its initial state.

[0066] Furthermore, after irradiation, the material can be heated at 90-120°C for 5-10 days, and the material will return from dark purple to colorless. Similarly, because heating causes the free radical signal to disappear, the material's color will return to its initial state.

[0067] Furthermore, after irradiation, the material can be irradiated with 365nm UV light for 1-2 days, causing it to revert from a deep purple color to colorless. This is because UV irradiation weakens the free radical signal, allowing the material's color to return to its initial state.

[0068] The present invention relates to a millimeter-scale thorium cluster single crystal material used as a radiation shielding material in radiation protection. The irradiation source includes X-rays, and the detection method includes testing the radiation shielding effect and the ray blocking rate.

[0069] The steps for establishing testing standards include irradiating the thorium cluster compound single crystal material of the present invention with an X-ray source of known output power, and further judging the differences in radiation shielding performance based on the color change of thorium cluster compound single crystal materials of different thicknesses or the change in photon count in the environment during irradiation;

[0070] The detection steps include irradiating the thorium cluster single crystal material of the present invention with X-rays of known output power, comparing the color change of the thorium cluster single crystal material or the change in photon count in the environment during irradiation with the detection standard, and thereby selecting an appropriate thickness of thorium cluster single crystal material as the standard thickness of the radiation protection material.

[0071] Furthermore, the X-ray target is W, and the output power is 15.5-16.5kV, 19.5-20.5μA.

[0072] When establishing the standard thickness of the shielding material, the original thorium cluster single crystal material is ground evenly and pressed into circular materials with a diameter of 15 mm and different thicknesses. The circular materials are placed near the X-ray source window to completely cover the X-ray source window. Then, the ability of the thorium cluster single crystal circular materials of different thicknesses to completely block X-rays during irradiation is recorded, so that X-ray photons do not escape from the source window. This is used as a standard to design a certain thickness of thorium cluster single crystal material as the standard thickness of the radiation shielding material.

[0073] This invention uses 3-pyridin-4-yl-phenylcarboxylic acid as a ligand, which coordinates with tetravalent thorium under solvothermal conditions to crystallize. The crystalline material exhibits irradiation discoloration under X-ray irradiation. This material can be used for qualitative and quantitative detection and calibration after high-dose X-ray irradiation. Compared with traditional irradiation discoloration indicator labels, it achieves both visual qualitative and quantitative detection, while also exhibiting strong irradiation stability, high reusability, and high radiation blocking efficiency. It can also be used as a radiation shielding material.

[0074] Example 1

[0075] This embodiment synthesizes materials and tests the crystal structure stability under different irradiation conditions to verify that the materials in this invention can be practically applied under various high-dose irradiation conditions without causing radiation damage to the materials.

[0076] 0.05 mmol of Th(NO3)4·6H2O solid, 0.05 mmol of 3-pyridin-4-yl-phenylcarboxylic acid solid, 4.5 wt% perchloric acid, 0.8 mL of H2O, and 0.2 mL of DMF were placed in a 5 mL glass vial, sealed, and heated to 100 °C for 5 days. After the reaction was complete, a transparent, large-scale crystalline product was obtained. The crystalline product was removed from the vial and washed with ethanol solution, then dried at room temperature to obtain a thorium cluster compound single crystal material, hereinafter referred to as the crystalline material. The reaction route is as follows:

[0077]

[0078] Figure 1 This is a schematic diagram of the structure of the millimeter-scale thorium cluster compound single crystal material in this embodiment. The millimeter-scale thorium cluster compound single crystal is composed of a 0-dimensional cluster structure, in which tetravalent thorium ions are hydrolyzed and polymerized to form a hexanuclear thorium cluster center [Th6(OH)4(O)4(H2O)6]. 12+ Thorium ions communicate with each other via O 2- and OH - The structure is further modified to connect six 3-pyridin-4-yl-phenylcarboxylic acid ligands and six formic acid anions. The periodic staggered arrangement of the 0-dimensional clusters leads to strong π-π interactions between the pyridine rings, and the structure is arranged in a long-range ordered manner.

[0079] After obtaining millimeter-sized thorium cluster single crystal materials according to the above method, the millimeter-sized thorium cluster single crystal materials were irradiated with 365nm UV excitation light for 2 hours, irradiated with 10kGy dose by X-ray source (12W), and irradiated with 100kGy dose by β-rays generated by electron cyclotron accelerator (1.2MeV).

[0080] The millimeter-scale thorium cluster single crystals before and after irradiation were characterized using powder diffraction, such as... Figure 2 As shown, Figure 2In the simulation, the powder curve of the millimeter-scale thorium cluster single crystal structure was consistent with the peak shape of the curve obtained by X-ray powder diffraction of the crystal sample. This indicates that the millimeter-scale thorium cluster single crystal powder sample had very good purity before irradiation and was free of other impurity phases. Powder diffraction patterns were measured after UV, X-ray, and β-ray irradiation, respectively. Figure 2 The main characteristic peak shapes are the same as those of the powder diffraction peaks of the sample before irradiation, which objectively shows that the crystal morphology has not changed after irradiation and can be applied to the research of irradiation detection and radiation shielding materials.

[0081] like Figure 3 As shown, the Fourier transform infrared spectra of the millimeter-scale thorium cluster single crystal material in this embodiment remain consistent before and after irradiation, indicating that the chemical bonds in the crystal did not break before and after irradiation, and the bonding mode remained basically unchanged. This also indicates that the framework structure of the material is stable and no collapse phenomenon has occurred.

[0082] Thermal stability of millimeter-scale thorium cluster single crystal material in this embodiment

[0083] In this embodiment, the synthesized millimeter-scale thorium cluster single crystal material was subjected to thermal stability testing to verify that the millimeter-scale thorium cluster single crystal material of the present invention can be used at different temperatures.

[0084] The millimeter-scale thorium cluster compound single-crystal material generated in this embodiment was characterized using TG data analysis, such as... Figure 4 As shown, it is demonstrated that the crystalline material is structurally stable before 100℃. The water molecules and solvent molecules in the material defects begin to collapse after 250℃, which is between 100-250℃. Therefore, it is proven that the material is thermally stable and can be used cyclically below 100℃.

[0085] This embodiment demonstrates the reversible color change and recyclability of millimeter-scale thorium cluster single crystals.

[0086] The millimeter-scale thorium cluster single crystal material of this embodiment was irradiated with X-rays and then subjected to fading treatment to verify the reversible color change phenomenon of the millimeter-scale thorium cluster single crystal material after irradiation and its recyclability.

[0087] The millimeter-scale thorium cluster single crystal material prepared in this embodiment was irradiated with more than 1 kGy under an X-ray source (12W). The crystal changed from colorless to deep purple. Then it was stored in a dark room, heated at 100°C, or irradiated with 365nm UV light. Figure 5 As shown, it was found that the millimeter-sized thorium cluster single crystal completely faded after two months in a dark room, and the crystal that had changed color also completely faded after being heated at 100°C for two days. After being irradiated under 365nm UV for one day, the crystal color completely faded. This indicates that all three treatment methods can reversibly change the color of the millimeter-sized thorium cluster single crystal material back to the original transparent crystal, and the millimeter-sized thorium cluster single crystal material can be reused for radiation detection applications.

[0088] This embodiment presents the selective irradiation color-changing performance test and mechanism analysis of a 4 mm-sized thorium cluster single crystal.

[0089] The millimeter-scale thorium cluster single crystal material of this embodiment was used for UV and X-ray irradiation. The single crystal material prepared in this embodiment was placed on a quartz glass slide, and the UV-vis absorption spectrum of the crystal color before and after X-ray irradiation under white light was measured using a solid-state spectrometer. Under cumulative X-ray dose irradiation, the crystal color gradually deepened to a deep purple, and the intensity of the characteristic absorption peaks in the absorption spectrum also gradually changed, as shown in Figures 6(a) and 6(b). The characteristic absorption peak at 318 nm in the ultraviolet region decreased, while the characteristic peak at 372 nm increased. The characteristic peaks in the visible region (450-700 nm) increased overall, indicating that the white light transmittance decreased and the absorption of white light increased, thus the crystal color deepened. However, when irradiated with 365 nm UV and the absorption spectrum of the irradiated single crystal was collected in the same way, the crystal color and absorption spectrum did not change significantly after long-term irradiation, proving that the material has a selective color-changing response to X-rays and can be used for the detection of ionizing radiation, avoiding interference from non-ionizing radiation irradiation.

[0090] Figure 7 The changes in the intensity of free radical signals after cumulative X-ray irradiation of millimeter-scale thorium cluster single crystal materials, and the decay of free radical signals at different time periods under 365nm UV irradiation, indicate that the more free radicals generated by X-ray excitation, the more discoloration occurs in the single crystal material, and the purple color becomes deeper as the free radical signal increases. However, after UV irradiation, the free radical signal decreases, so the deep purple color gradually fades after X-ray irradiation and gradually fades back to the initial transparent color. It can be seen that the formation and decay of free radicals are the main reasons for the purple discoloration and reduction fading of crystal materials after irradiation.

[0091] Qualitative and quantitative analysis of the X-ray irradiation color change response of millimeter-scale thorium cluster single crystal materials in this embodiment.

[0092] The single crystal material of this embodiment was placed under X-rays for irradiation experiments. The color signal changes of the crystal before and after irradiation were compared. At the same time, the changes in UV-vis absorption spectrum after irradiation with different doses were tested. The X-ray irradiation dose was quantified by linear fitting of the characteristic absorption peak intensity and the cumulative irradiation dose, so as to verify that the irradiation color change effect of the material of this invention can be used for qualitative and quantitative detection of X-rays.

[0093] The UV-Vis absorption spectrum of a raw crystal sample was measured and photographed using a solid-state spectrometer. The sample was then irradiated with X-rays at doses of 0 Gy, 90 Gy, 240 Gy, 360 Gy, 600 Gy, 900 Gy, 1200 Gy, 1800 Gy, 2400 Gy, 3000 Gy, and 4000 Gy. The absorption spectra after irradiation were then measured at different cumulative irradiation doses. Based on the change in absorption intensity at the characteristic absorption peak of 372 nm in the spectrum, a linear relationship was fitted with the cumulative irradiation dose. Figure 8 As shown, the emission peak of the crystal increases at 372 nm before X-ray irradiation. Simultaneously, the fitting results show that the absorption spectrum of the crystal remains basically unchanged under irradiation doses below 1200 Gy. Within the dose range of 1.2-4 kGy, the change in absorption peak intensity is linearly positively correlated with the cumulative irradiation dose. Therefore, it can be used for dose detection and calibration of 1.2-4 kGy under X-ray (W target) irradiation.

[0094] The color change of a raw crystal sample after cumulative X-ray irradiation was captured using a photographic system. The cumulative irradiation doses were 0 Gy, 400 Gy, 750 Gy, 1200 Gy, 1800 Gy, 2400 Gy, 3600 Gy, and 4800 Gy. The irradiated single crystal was photographed under the same exposure intensity. Figure 9 As shown, it was found that as the cumulative dose increased, the color of the irradiated surface of the large crystal gradually turned purple and the color intensity gradually deepened. Therefore, the cumulative X-ray irradiation dose can be qualitatively identified by the naked eye, and qualitative detection and identification of X-rays can be performed.

[0095] This embodiment tests the radiation shielding performance of a 6mm-scale thorium cluster single-crystal material.

[0096] In this embodiment, a millimeter-scale thorium cluster single crystal sample was irradiated with X-rays. The X-ray source's exit window was completely blocked by a crystal wafer, and the photon count at the radiation background at the X-ray source window was tested to verify that the crystal wafer material of standard thickness in this invention can completely block X-ray photons and play a role in radiation shielding.

[0097] As shown in Figures 10(a) and 10(b), the synthesized millimeter-sized single crystal (3×3×3mm) was first irradiated with 4.8 kGy of X-rays. It can be seen that the irradiated crystal surface can block X-ray photons. After irradiation, the discoloration depth on the side of the crystal is 0.25mm-0.75mm. At this point, the X-rays cannot penetrate the single crystal at all, demonstrating a very good radiation protection effect.

[0098] A large amount of synthesized crystal material was ground and pressed into cylindrical sheets, as shown in Figures 11(a) and 11(b). The diameter of the cylindrical sheets was 15 mm, and the thicknesses were 0.4 mm, 0.8 mm, and 1.2 mm, respectively. First, the photon count rate of the background and the X-ray energy spectrum signal received by the detector were measured at a position 40 mm directly opposite the X-ray source exit port using a scintillator detector. Then, the X-ray source (W target, 16 kV / 20 μA) was turned on, and the X-ray emission energy spectrum and photon count rate at that position were measured. Then, the exit window of the X-ray source was covered with discs of different thicknesses, and the X-ray emission energy spectrum and photon count rate at that position were measured. As shown in Figures 12(a) and 12(b), a 0.4 mm thick crystal wafer can block 83.35% of X-ray photons, a 0.8 mm thick crystal wafer can block 97.89% of X-ray photons, and a 1.2 mm thick crystal wafer can block 99.73% of X-ray photons. It can be seen that crystal wafers thicker than 1.2 mm can completely block all X-ray photons from the emission window of the X-ray source (W target, 16 kV / 20 μA).

[0099] The above results indicate that the millimeter-scale crystal material of this invention exhibits selective irradiation color-changing response to X-rays, enabling visual qualitative detection of high-dose X-rays and quantitative detection of cumulative dose. It is an excellent material for irradiation color-changing dosimeters, which can utilize the X-ray irradiation color-changing effect to analyze the magnitude of irradiated radiation dose. It is also a highly efficient ionizing radiation shielding material, which can play a role in radiation protection.

[0100] As can be seen from the above results, the present invention has the following characteristics:

[0101] (1) This invention introduces actinide thorium to construct thorium metal cluster single crystal material as a new type of radiation color change detection material. Compared with traditional hybrid materials, inorganic materials, polymer materials, etc., it has a wider detection limit and stronger radiation blocking ability.

[0102] (2) The thorium cluster compound single crystal material of the present invention has strong irradiation stability and high reusability;

[0103] (3) In this invention, the thorium cluster compound single crystal material can be used to achieve qualitative or quantitative detection of X-rays by utilizing the irradiation color change effect, and the millimeter-scale single crystal can achieve visual detection of X-rays.

[0104] (4) This invention uses millimeter-scale single-crystal materials to make radiation shielding materials, which can achieve efficient protection and shielding of radiation;

[0105] (5) The present invention provides a millimeter-scale single crystal material that can be used to qualitatively or quantitatively determine the radiation dose by irradiation color change and simultaneously shield the radiation. It achieves a very wide range of irradiation detection limits, realizes accurate dose detection by using the change of material color, and also plays a role in radiation protection.

[0106] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the technical principles of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for synthesizing millimeter-scale thorium cluster single crystals, characterized in that, The process includes the following: A water-soluble thorium salt was reacted with 3-pyridin-4-yl-phenylcarboxylic acid in a mixed solvent in a solvothermal reaction. After the reaction was complete, a transparent bulk crystal was obtained. The transparent bulk crystal was washed and dried to obtain the millimeter-sized thorium cluster single crystal. The chemical formula of the millimeter-sized thorium cluster single crystal is [Th6O4(OH)4(H2O)6](H8C 12 NO2)6(COOH)6; The mixed solvent contains water, inorganic acid, and organic solvent; The inorganic acid used is perchloric acid, and the mass content of perchloric acid in the mixed solvent is 4.5%, and the pH value of the solvothermal reaction system is not greater than 1.5; The organic solvent used is N,N'-dimethylformamide, and the volume ratio of water to N,N'-dimethylformamide is (3-5):1; The molar ratio of water-soluble thorium salt to 3-pyridin-4-yl-phenylcarboxylic acid is 1:1; In the solvothermal reaction system, the concentration of water-soluble thorium salt is 0.02-0.10 mmol / mL; The water-soluble thorium salt is thorium nitrate; During the solvothermal reaction, the reaction temperature is 90-120℃ and the reaction time is 5-10 days.

2. A millimeter-scale thorium cluster compound single crystal, characterized in that, The millimeter-scale thorium cluster single crystal was prepared by the synthesis method described in claim 1, and the chemical formula of the millimeter-scale thorium cluster single crystal is as follows: [Th6O4(OH)4(H2O)6](H8C 12 NO2)6(COOH)6; The metal center of the millimeter-scale thorium cluster single crystal is tetravalent thorium, and the ligand is 3-pyridin-4-yl-phenylcarboxylic acid; The millimeter-sized thorium cluster single crystal can produce irradiation discoloration under irradiation conditions. After the millimeter-sized thorium cluster single crystal undergoes irradiation discoloration, it can recover to its original color before irradiation.

3. The application of the millimeter-scale thorium cluster single crystal according to claim 2, characterized in that, The millimeter-scale thorium cluster single crystal is used in X-ray cumulative dose detection.

4. The application of the millimeter-scale thorium cluster single crystal according to claim 2, characterized in that, The millimeter-sized thorium cluster single crystal is used as a radiation shielding material in radiation protection.

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