Radiochromic material as well as preparation method and application thereof

Abstract

The invention discloses a radiochromic material and a preparation method and application thereof, and particularly relates to the field of radiation dose monitoring. The chemical formula of the radiochromic material is AF2: xB, wherein A is Ca < 2 + >, Ba < 2 + > or Sr < 2 + >, B is rare earth element La < 3 + >, Ce < 4 + >, Sm < 3 + >, Eu < 3 + >, Tb < 3 + > or Dy < 3 + >, and x is more than or equal to 0.0001 and less Wherein raw materials of the radiochromic material comprise a source A and a source B, the source A is fluoride of an element A, and the source B is one or a mixture of oxide and fluoride of an element B; the radiochromic material can change from white to grey blue under ionizing radiation. The radiochromic material is sensitive to ionizing radiation response, the lower detection limit can reach 30 mGy, the crystal structure is simple, the forbidden band width is large, and the chemical stability is good.

Description

Technical Field

[0001] This application relates to the field of radiation dose monitoring, and in particular to a radiation-chromatic material, its preparation method, and its application. Background Technology

[0002] Currently, commonly used personal dosimeters mainly include electronic dosimeters, fluorescent solid-state dosimeters (thermoluminescent dosimeters, optically stimulated luminescence dosimeters, and radiation photoluminescence dosimeters), and radiochromic dosimeters. Radiochromic dosimeters are a type of dosimeter that undergoes a significant color change under ionizing radiation. Their dose information can be directly and quickly indicated by the degree of color change, giving them a clear advantage in scenarios requiring timely dose information, such as high-radioactive environments and nuclear accident emergency response, making them ideal personal dosimeters.

[0003] Currently, common color-changing radiation dosimeters are usually based on organic polymers, such as plexiglass, GEX B3 series thin-film dosimeters, FWT-60 and Fricke dosimeters, etc. The color-changing process of these dosimeters mainly depends on the polymerization reaction of their internal active molecules. They usually require a high irradiation dose to produce a strong degree of polymerization. At the same time, the polymerization reaction process usually takes a long time. This leads to problems such as low sensitivity and long waiting time after irradiation, making it difficult to apply them to personal radiation dose monitoring. Summary of the Invention

[0004] The main purpose of this application is to provide a radiation-chromatic material, its preparation method, and its application, aiming to solve the problems of low sensitivity and long waiting time after irradiation in existing dosimeter materials.

[0005] To achieve the above objectives, this application provides a radiochromic material with the chemical formula AF2:xB; wherein A is Ca 2 + Ba 2+ or Sr 2+ B is the rare earth element La. 3+ Ce 4+ 、Sm 3+ Eu 3+ 、Tb 3+ or Dy 3+ , 0.000≤x≤0.02; wherein, the raw materials of the radiochromic material include source A and source B, source A is a fluoride of element A, and source B is one or a mixture of two of the oxide and fluoride of element B; the radiochromic material can change color from white to grayish-blue under ionizing radiation.

[0006] To achieve the above objectives, this application also provides a method for preparing a radiochromic material, comprising: mechanically activating a source A to obtain a precursor powder; pressing the precursor powder in a mold to obtain a green body; and sintering the green body at a temperature of 600-1000℃ for 4-10 hours to obtain the radiochromic material.

[0007] Optionally, the precursor powder may also include a B source.

[0008] Optionally, the precursor powder is prepared by placing source A in a ball mill jar, adding lubricant, and ball milling at a speed of 100-200 rpm for 60-300 min to obtain powder of 2-10 µm; drying the powder at a temperature of 50-70℃ for 4-8 h to obtain precursor powder.

[0009] Optionally, the green body is prepared by adding an adhesive to the precursor powder and granulating it to obtain a mixture; placing the mixture in a mold and pressing it under a pressure of 2-20 MPa for 30-120 s to obtain the green body.

[0010] Optionally, the heating rate during the sintering process is 3-8℃ / min.

[0011] To achieve the above objectives, this application also provides the application of a radiation-chromatic material in a dosimeter.

[0012] Optionally, the measurement method for radiochromic materials is as follows: under ionizing radiation, the radiochromic material undergoes a color change process from white to grayish-blue, and the radiation dose information is determined based on the degree of color change, or by reading the reflectance spectrum of the dosimeter.

[0013] Optionally, the dosimeter has a detection limit of 30 mGy and a response time of less than 1 s.

[0014] Compared with the prior art, the beneficial effects of this application are as follows: The radiochromic material of this invention, using an A source as raw material, undergoes a color-changing process from white to grayish-blue under ionizing radiation; during high-temperature sintering, the radiochromic material can generate a large amount of F related to the radiochromic process. - gap and F - The vacancy defect makes it highly sensitive to ionizing radiation, with a detection limit of 30 mGy, thus improving sensitivity. The crystal structure is simple, with a large band gap and good chemical stability. The raw materials required for preparation are inexpensive and readily available. It can be obtained by one-step sintering using the traditional solid-state sintering method. The preparation process is simple, and the resulting samples have a high yield and low cost, making it suitable for large-scale production applications.

[0015] When the radiochromic material of the present invention is used to measure the dose of a radiation agent, the degree of color change is related to the radiation dose received. The dose information can be qualitatively or semi-quantitatively indicated by the degree of color change, or quantitatively read by measuring the reflectance spectrum of the dosimeter. The dose result is simple and direct to read, so it can be used as a good personal dosimeter material. Attached Figure Description

[0016] Figure 1 The XRD pattern of the sample obtained in Example 1 of this application; Figure 2 This is a radiochromic image of the sample obtained in Example 1 of this application after being irradiated with different doses of X-rays; Figure 3 The reflectance spectra of the sample obtained in Example 1 of this application after X-ray irradiation at different doses are shown. Figure 4 The dose response curve of the sample obtained in Example 1 of this application; Figure 5 The XRD pattern of the sample obtained in Example 4 of this application; Figure 6 This is a radiochromic image of the sample obtained in Example 4 of this application after being irradiated with different doses of X-rays; Figure 7 The reflectance spectra of the sample obtained in Example 4 of this application after X-ray irradiation at different doses are shown. Figure 8 This is the dose response curve of the sample obtained in Example 4 of this application; The realization of the purpose, functional features and advantages of this application will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0017] To make the objectives, technical solutions, and advantages of this application clearer, the technical solutions of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0018] The first embodiment of the present invention provides a radiochromic material with the chemical formula AF2:xB; wherein A is Ca 2+ Ba 2+ or Sr 2+ B is the rare earth element La. 3+ Ce 4+ 、Sm 3+ Eu 3+ 、Tb 3+ or Dy 3+0.000≤x≤0.02; wherein, the raw materials of the radiochromic material include source A and source B, source A is a fluoride of element A, and source B is one or a mixture of two of the oxides and fluorides of element B. The radiochromic material can change color from white to grayish-blue under ionizing radiation.

[0019] In this embodiment, during the high-temperature sintering process, fluoride ions in the AF2 crystal gain sufficient energy due to thermal motion to detach from their normal lattice positions and form fluoride ions. - Vacancy defects or gaps entering AF2 form F - Interstitial defects. Under ionizing radiation, electrons transfer and transition within these defects, resulting in optical absorption and causing color change. The radiochromic properties are determined by the Fo in the material. - gap and F - The concentration of vacancies and related defects determines the concentration. The introduced B source is a trivalent or tetravalent rare earth ion, which will anisovalently substitute for the divalent cation at the A site during high-temperature sintering. To maintain charge balance, this will result in the generation of more F in the material. - Vacancies are created, thereby optimizing the radiation color-changing performance.

[0020] The second embodiment of the present invention provides a method for preparing a radiochromic material, specifically including the following steps: Step S1: Mechanically activate source A to obtain precursor powder; For example, mechanical activation is performed by high-energy ball milling or grinding. During the mechanical activation process, an appropriate amount of alcohol solution is added as a lubricant to improve the mechanical activation efficiency. Specifically, when mechanical activation is performed by high-energy ball milling, the precursor powder is prepared as follows: source A is placed in a ball milling jar, a lubricant is added, and the mixture is ball-milled at 100-200 rpm for 60-300 min to obtain powder with a particle size of 2-10 µm; the powder is then dried at 50-70°C for 4-8 h to obtain the precursor powder. Furthermore, the precursor powder also includes source B.

[0021] Step S2: The precursor powder is placed in a mold and pressed to obtain a green body; Specifically, an adhesive is added to the precursor powder for granulation to obtain a mixture; the mixture is placed in a mold and pressed under a pressure of 2-20 MPa for 30-120 s to obtain a green body.

[0022] Furthermore, the mixture obtained from granulation is sieved to a mesh size of 50-150 to obtain powder with good particle dispersibility, which is convenient for subsequent tableting.

[0023] Step S3: Sinter the green blank at a temperature of 600-1000℃ for 4-10 hours to obtain a radiation-chromic material. The heating rate during the sintering process is 3-8℃ / min. If the sintering temperature of the green blank is too low, the crystallinity of the obtained sample will be poor. If the sintering temperature is too high, some raw material components will volatilize and deviate from the original stoichiometric ratio.

[0024] In this embodiment, mechanical activation can, on the one hand, mix the raw materials evenly, and on the other hand, refine the particle size of the raw materials to 2-10µm, thereby increasing the surface activation energy of the material and facilitating subsequent sintering and molding.

[0025] A third embodiment of the present invention provides an application of the radiochromic material of claim 1 in a dosimeter. The method for measuring the radiochromic material involves the material undergoing a color change from white to grayish-blue under ionizing radiation, and the radiation dose information is determined based on the degree of color change, or by reading the reflectance spectrum of the dosimeter. Compared with traditional color-changing dosimeters, the dosimeter of the present invention has the following advantages: (1) Compared with the color change from white to dark gray that usually occurs in traditional color-changing dosimeters, the color change of AF2 is more obvious, making it easier to determine the irradiation dose by the degree of color change; (2) The effective atomic number of the AF2 matrix is ​​16.5, which is close to that of human tissue, giving it good tissue equivalence. This makes the absorbed dose measured by the color-changing material closer to the absorbed dose of the organism to be monitored, thus eliminating the need for subsequent dose calibration; (3) The photochromic phenomenon of AF2 is caused by the transfer and transition of electrons in different defects. The color change process does not involve chemical reactions, making its color change process rapid with a response time as fast as 1 second; (4) The special crystal structure of AF2 makes it easy to generate more F during the high-temperature preparation process. - gap and F - The vacancy greatly enhances its radiation color change sensitivity, making the dosimeter's detection limit 30 mGy.

[0026] Example 1 Weigh 5g of CaF2 chemical raw material and place it in a ball mill jar. After adding alcohol, ball mill at 200 rpm for 60 min for mechanical activation. Place the ball-milled mixture in an oven and dry it at 60℃ for 5 h to obtain precursor powder. Place the dried powder in an agate mortar and add an appropriate amount of polyvinyl alcohol (PVA) glue. After grinding thoroughly, sieve it through a 100-mesh sieve. Weigh 0.5g of the sieved powder each time and place it in a mold. Press it into a green body under a pressure of 5MPa for 1 min. Place the green body into a tube sintering furnace under an air atmosphere for sintering. The sintering parameters are set as follows: heating rate of 5℃ / min, from room temperature to 700℃, holding for 4 h, and then naturally cooling to room temperature with the furnace temperature to obtain the target sample CaF2.

[0027] Example 2 Weigh 8g of CaF2 chemical raw material and place it in a ball mill jar. Add an appropriate amount of alcohol and ball mill at 100 rpm for 300 min for mechanical activation. Place the ball-milled mixture in an oven and dry it at 60℃ for 5 h to obtain precursor powder. Place the dried powder in an agate mortar and add an appropriate amount of PVA adhesive. Grind thoroughly and then sieve through an 80-mesh sieve. Weigh 0.5g of the sieved powder each time and place it in a mold. Press it into a green body under a pressure of 5 MPa for 1 min. Place the green body into a tube sintering furnace under an air atmosphere for sintering. The sintering parameters are set as follows: heating rate of 5℃ / min, from room temperature to 900℃, holding for 6 h, and then naturally cooling to room temperature with the furnace temperature to obtain the target sample CaF2.

[0028] Example 3 Weigh 5g of CaF2 chemical raw material and place it in a mortar. Disperse it in 10mL of anhydrous ethanol and grind it at room temperature for 20min to grind the raw material into a uniform and dry powder. Add an appropriate amount of PVA glue to the uniform and dry powder for granulation. Continue grinding into uniform fine particles and then use a tablet press to compress the powder into tablets. Finally, place the compressed tablets into a tube furnace and heat it from room temperature to 700℃. Keep it at this temperature for 4h and then let it cool naturally to room temperature with the furnace temperature to obtain the target sample CaF2.

[0029] Example 4 Five grams of the chemical raw materials CaF2 and TbF3 were weighed together at a molar ratio of 1:0.01 and placed in a ball mill jar. After adding an appropriate amount of alcohol, the mixture was ball-milled at 200 rpm for 60 min for mechanical activation. The mixture obtained from ball milling was placed in an oven and dried at 60°C for 5 h to obtain precursor powder. The dried powder was placed in an agate mortar and an appropriate amount of PVA adhesive was added. After grinding thoroughly, the powder was sieved through a 100-mesh sieve. The sieved powder was weighed in batches of 0.5 g and placed in a mold. The mold was pressed into green blanks by holding the mold under a pressure of 5 MPa for 1 min. The green blanks were then placed in a tube sintering furnace under an air atmosphere. The sintering parameters were set as follows: the heating rate was 5°C / min, the temperature was raised from room temperature to 700°C, and the temperature was held for 4 h. The green blanks were then allowed to cool naturally to room temperature with the furnace temperature to obtain the target sample CaF2:0.01Tb.

[0030] Example 5 Five grams of the chemical raw materials CaF2 and EuF3 were weighed together at a molar ratio of 1:0.01 and placed in a ball mill jar. After adding an appropriate amount of alcohol, the mixture was ball-milled at 200 rpm for 60 min for mechanical activation. The mixture obtained from ball milling was placed in an oven and dried at 60°C for 5 h to obtain precursor powder. The dried powder was placed in an agate mortar and an appropriate amount of PVA adhesive was added. After grinding thoroughly, the powder was sieved through a 100-mesh sieve. The sieved powder was weighed in batches of 0.5 g and placed in a mold. The mold was pressed into green blanks by holding the mold under a pressure of 5 MPa for 1 min. The green blanks were then placed in a tube sintering furnace under an air atmosphere. The sintering parameters were set as follows: heating rate of 5°C / min, heating from room temperature to 700°C, holding for 4 h, and then naturally cooling to room temperature with the furnace temperature to obtain the target sample CaF2:0.01Eu.

[0031] Example 6 Five grams of the chemical raw materials CaF2 and Eu2O3 were weighed together at a molar ratio of 1:0.005 and placed in a ball mill jar. After adding an appropriate amount of alcohol, the mixture was ball-milled at 200 rpm for 60 min for mechanical activation. The mixture obtained from ball milling was placed in an oven and dried at 60°C for 5 h to obtain precursor powder. The dried powder was placed in an agate mortar and an appropriate amount of PVA adhesive was added. After grinding thoroughly, the powder was sieved through an 80-mesh sieve. 0.5 g of the sieved powder was weighed each time and placed in a mold. The mold was pressed into a green body under a pressure of 3 MPa for 1 min. The green body was then placed in a tube sintering furnace under an air atmosphere. The sintering parameters were set as follows: heating rate of 5°C / min, from room temperature to 900°C, holding for 4 h, and then naturally cooled to room temperature with the furnace temperature to obtain the target sample CaF2:0.01Eu.

[0032] The XRD pattern of the CaF2 sample obtained in Example 1 is as follows: Figure 1 As shown, by comparing with the standard diffraction card PDF#75-0363, the diffraction peaks of the obtained sample correspond well with the standard diffraction card, indicating that the pure phase target sample can be successfully synthesized under these synthesis conditions.

[0033] The radiochromic images of the sample obtained in Example 1 after X-ray irradiation with different doses are shown below. Figure 2 As shown in the figure, under ionizing radiation, the sample undergoes a color change from white to grayish-blue, and the degree of color change gradually deepens with increasing irradiation dose. This dose-dependent color change process makes it suitable for personal radiation dose monitoring, providing a direct and rapid indication of radiation dose through the degree of color change. Furthermore, the sample exhibits a significant color change with clear color contrast at an X-ray irradiation dose of 30 mGy, indicating that the lower limit of radiation dose detection for the sample is below 30 mGy.

[0034] Figure 3 The figures show the reflectance spectra of the sample obtained in Example 1 after X-ray irradiation at different doses. As can be seen from the figures, under ionizing irradiation, the reflectance of the sample in the 300-450 nm and 470-700 nm wavelength bands gradually decreases with increasing irradiation dose. There is a one-to-one correspondence between reflectance intensity and irradiation dose, which allows for the quantitative reading of the irradiation dose received by the sample by measuring its reflectance spectrum.

[0035] Figure 4 The figure shows the dose response curve of the sample obtained in Example 1. The integral intensity of the reflectance change in the range of 220-850 nm is used as the dose response parameter. It can be seen from the figure that the integral intensity of the reflectance change increases monotonically with the increase of the irradiation dose, but the linear dose response range is relatively narrow.

[0036] The XRD pattern of the CaF2:0.01Tb sample obtained in Example 4 is as follows: Figure 5 As shown, by comparing with the standard diffraction card PDF#75-0363, the diffraction peaks of the obtained sample correspond well with the standard diffraction card, indicating that the doping of trace amounts of Tb in the CaF2 matrix... 3+ The ions do not affect the phase structure, and the target sample in pure phase can be successfully synthesized under these synthetic conditions.

[0037] Figure 6 The images show the radiochromic changes of the sample obtained in Example 4 after X-ray irradiation at different doses. The CaF2:0.01Tb sample exhibits similar radiochromic characteristics to the CaF2 sample obtained in Example 1. Under ionizing radiation, the sample changes color from white to grayish-blue, and the degree of color change gradually deepens with increasing irradiation dose. This dose-dependent color change process makes it suitable for personal radiation dose monitoring, as the radiation dose information can be intuitively and quickly indicated by the degree of color change. Furthermore, the sample also exhibits a significant color change at an X-ray irradiation dose of 30 mGy, with clear color contrast, indicating that the lower limit of radiation dose detection for the sample is below 30 mGy.

[0038] Figure 7 The image shows the reflectance spectra of the sample obtained in Example 4 after X-ray irradiation at different doses. Under ionizing irradiation, the reflectance of the sample in the 300-450 nm and 470-700 nm wavelength bands gradually decreased with increasing irradiation dose. There is a one-to-one correspondence between reflectance intensity and irradiation dose, which allows for the quantitative reading of the irradiation dose information of the sample by measuring the reflectance spectrum of the irradiated sample.

[0039] Figure 8The figure shows the dose response curve of the sample obtained in Example 4. Using the integral intensity of the reflectance change in the 220-850 nm range as the dose response parameter, it can be seen from the figure that the integral intensity of the reflectance change increases monotonically with increasing irradiation dose. Meanwhile, Example 4 exhibits a good linear dose response in the 30-120 mGy range. This indicates that, compared to Example 1, adding a B source in Example 4 can increase the linear dose response range.

[0040] The above are merely preferred embodiments of this application and do not limit the patent scope of this application. Any equivalent structural or procedural transformations made using the content of this application's specification and drawings, or direct or indirect applications in other related technical fields, are similarly included within the patent protection scope of this application.

Claims

1. A radiochromic material, characterized in that, Its chemical formula is AF2:xB; Where A is Ca 2+ Ba 2+ or Sr 2+ B is the rare earth element La. 3+ Ce 4+ 、Sm 3+ Eu 3+ 、Tb 3+ or Dy 3+ , 0.000≤x≤0.02; The raw materials of the radiation-chromatic material include source A and source B, wherein source A is a fluoride of element A, and source B is one or a mixture of two of the oxides and fluorides of element B. The radiochromic material can change color from white to grayish-blue under ionizing radiation.

2. A method for preparing the radiochromic material according to claim 1, characterized in that, include: Source A is mechanically activated to obtain precursor powder; The precursor powder is placed in a mold and pressed to obtain a green body; The green body is sintered at a temperature of 600-1000℃ for 4-10 hours to obtain a radiation-chromatic material.

3. The method for preparing the radiochromic material according to claim 2, characterized in that, The precursor powder also includes a B source.

4. The method for preparing the radiochromic material according to claim 2, characterized in that, The precursor powder is prepared by placing source A in a ball mill jar, adding lubricant, and ball milling at a speed of 100-200 rpm for 60-300 min to obtain powder of 2-10 µm; drying the powder at a temperature of 50-70℃ for 4-8 h to obtain precursor powder.

5. The method for preparing the radiochromic material according to claim 2, characterized in that, The preparation method of the green body is to add an adhesive to the precursor powder and granulate it to obtain a mixture; The mixture is placed in a mold and pressed under a pressure of 2-20 MPa for 30-120 seconds to obtain a green body.

6. The method for preparing the radiochromic material according to claim 2, characterized in that, The heating rate during the sintering process is 3-8℃ / min.

7. The application of the radiochromic material of claim 1 in a dosimeter.

8. The application of the radiochromic material according to claim 7 in a dosimeter, characterized in that, The method for measuring the radiochromic material is as follows: under ionizing radiation, the radiochromic material undergoes a color change process from white to grayish-blue. The dose information of the radiation agent is determined based on the degree of color change, or by reading the reflectance spectrum of the dosimeter.

9. The application of the radiochromic material according to claim 7 in a dosimeter, characterized in that, The dosimeter has a detection limit of 30 mGy and a response time of less than 1 s.

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