Rare earth erbium doped lithium tetraborate film photoluminescence dosimeter and preparation method thereof
The preparation of rare earth erbium-doped lithium tetraborate films at room temperature by sol-gel method, which solved the equipment complexity and film cracking problems caused by high-temperature preparation, achieved high crystallinity and uniformity, and improved the sensitivity of radiation dose measurement and range, reducing energy consumption and cost.
Patent Information
- Application Number
- CN202411393517.1
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-10-08
- Publication Date
- 2025-01-03
AI Technical Summary
The existing lithium tetraborate film preparation methods have problems such as increasing equipment complexity and cost due to high temperature environments, thermal expansion stresses lead to film cracking, boric acid volatility and microcrystal inhomogeneity, which affects the luminescence effect and measurement accuracy of the material.
The rare earth erbium doped lithium tetraborate film was prepared by hydrolysis and polymerization at room temperature by using sol-gel low-temperature wet chemistry method, and the viscosity was adjusted using tannin acid and tetraethylene pentamine, and the spin coating method was applied at 500-800. Calcination at °C to control the film thickness and crystallinity and reduce organic matter residues.
A rare earth erbium-doped lithium tetraborate film has been achieved with high crystallinity and uniformity, which improves the sensitivity and range of radiation dose measurement, reduces energy consumption and cost, simplifies processes, and facilitates large-scale production.
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Figure CN119247437A_ABST
Abstract
Description
Technical Field
[0001] The invention relates to the field of radiation dose measurement, and in particular to an optically stimulated luminescence dose meter of a rare earth erbium-doped lithium tetraborate film and a preparation method thereof. Background Art
[0002] OSL has a wide range of applications in radiation detection and protection, personal and environmental dose monitoring, nuclear medicine and medical physics, space exploration and other fields. OSL dosimeters based on luminescence dosimetry have the advantages of high sensitivity, high measurement accuracy, wide range, flexible size, automatic reading and potential identification in mixed radiation fields, and have gradually become one of the most reliable and commonly used methods for radiation dose monitoring. When a material is irradiated by X-rays, gamma rays, alpha particles, beta particles, protons, neutrons and high-energy particles, when the radiation absorption energy is greater than the band gap, it will cause the ionization of valence band electrons, and then the carriers will be captured by the trap energy level; subsequently, under the action of light, the captured electrons absorb energy and release back to the conduction band, and the free electrons in the conduction band and the captured holes undergo indirect recombination to produce luminescence. The intensity of the emitted light is a function of the radiation dose absorbed by the sample, so it can be used to measure radiation dose. The photoluminescence process can release electrons trapped in deep electron traps that cannot be released by the general thermoluminescence process by selecting the wavelength of the excitation light and the readout temperature. That is, the photoluminescence process may release more trapped electrons. Therefore, the measurement sensitivity of photoluminescence of certain materials is high.
[0003] The absorption of radiation energy is closely related to the primary atomic number of the material's isotope content. Lithium tetraborate (Li2B4O7) has a similar equivalent atomic number to human tissue. Lithium tetraborate films with a thickness of less than 1 micron can simulate human skin and have a wide range of applications in nuclear medicine and medical physics. In terms of radiation protection, it contains the element 10 B and 6 Li can react with neutrons, has good neutron shielding and high detection sensitivity. Rare earth doped lithium tetraborate can improve the accuracy of absorbed dose and the range of radiation dose measurement, and is one of the most ideal photoluminescence radiation detection dosimeters. Li2B4O7 doped with rare earth erbium can effectively increase the luminescence intensity, thereby improving the sensitivity and dose detection range.
[0004] The current method for preparing lithium tetraborate thin film has the following defects: first, the melting point of lithium tetraborate is relatively high (about 917°C), and a high temperature environment is required during the film preparation process, which may lead to increased equipment complexity and cost; second, due to the difference in thermal expansion coefficients, stress will be generated between the film and the substrate during the cooling process, causing the film to crack or peel off; third, the melting process at high temperature is likely to cause the volatilization of boric acid raw materials; fourth, the size of the precipitated microcrystals is very uneven, and during the crystallization process, it is difficult for rare earth luminescent ions to enter the lithium tetraborate lattice site, affecting the luminescence effect of the material. With the widespread popularization of civilian use, small and integrated radiation dosimeters are the inevitable path of future development. The present invention discloses a rare earth erbium doped lithium tetraborate thin film optically stimulated luminescence dosimeter and a preparation method thereof, which prepares a thin film with good uniformity, high crystallinity and high sensitivity in air. Summary of the invention
[0005] The purpose of the present invention is to provide a method for preparing a rare earth erbium doped lithium tetraborate film with high crystallinity, high sensitivity, wide detection range and strong anti-fading ability, so as to solve the problems of low crystallinity, uneven thickness and film cracking of lithium tetraborate film. The size and thickness of the crystallites in the synthesized film are uniform, and the doping concentration of rare earth erbium is high, which can meet the requirements of optically stimulated luminescence dosimeter based on environmental monitoring or medical physics for human body dose.
[0006] The optically stimulated luminescence dosimeter of a rare earth erbium-doped lithium tetraborate film and a preparation method thereof described in the present invention comprises the following steps:
[0007] (1) High-purity lithium carbonate powder and boric acid powder are uniformly mixed, and deionized water is added and stirred thoroughly to obtain a clear and transparent solution A;
[0008] (2) taking a tannic acid solution, adding a certain amount of deionized water, and performing a hydrolysis reaction at room temperature to prepare a solution B;
[0009] (3) Solution B is slowly added to Solution A, and after thorough mixing and stirring, tetraethylenepentamine is added to adjust the pH value, and erbium oxide powder is added to prepare a solution C of a certain viscosity;
[0010] (4) evenly coating solution C on a substrate by spin coating, drying the sample, and annealing the sample in a muffle furnace to obtain a rare earth erbium-doped lithium tetraborate thin film;
[0011] (5) The optically stimulated luminescence dosimeter includes a transparent shell and a rare earth erbium-doped lithium tetraborate film for detecting radiation signals.
[0012] The transparent shell is provided with a light-through hole corresponding to the light irradiated onto the dosage sheet.
[0013] In some embodiments, the molar ratio of lithium carbonate to boric acid is 1:4-4.8.
[0014] In some embodiments, the reaction time of the lithium carbonate and the boric acid solution is 0.5-5h.
[0015] In some embodiments, solution C is heated at 50-100° C. to have a certain viscosity.
[0016] In some of the embodiments, the molar ratio of erbium oxide to lithium tetraborate is controlled to be Er:Li2B4O7=0.005-0.05:1.
[0017] In some embodiments, the pH is 9-11.
[0018] In some embodiments, the drying temperature is 100-200°C, and the annealing temperature is 500-800°C.
[0019] In some embodiments, the drying time is 0.5-5h, and the annealing time is 0.5-5h.
[0020] In some embodiments, the dried sample is washed 2-3 times in anhydrous ethanol.
[0021] In some embodiments, the heating rate during annealing is 2-9°C / min.
[0022] Compared with the prior art, the rare earth erbium doped lithium tetraborate photoluminescent material of the present invention has the following essential characteristics:
[0023] (1) Sol-gel is a low-temperature wet chemical preparation technology that can prepare thin films at room temperature through the hydrolysis and polymerization chemical reaction of precursor raw materials;
[0024] (2) Selecting tannic acid and tetraethylenepentamine as gelling agents can enhance the viscosity of the gel, reduce film cracking, improve the uniformity of the coating process, and accurately control the thickness of the film;
[0025] (3) Calcination at 500-800°C can remove organic matter and improve crystallinity;
[0026] (4) The film prepared by the present invention has high sensitivity, and doping with erbium ions of different concentrations can improve the accuracy of absorbed dose and the measurement range of radiation dose. It also has low energy consumption, low cost, simple process, easy operation, and is convenient for large-scale production. BRIEF DESCRIPTION OF THE DRAWINGS
[0027] In order to more clearly illustrate the specific implementation of the present application or the technical solutions in the prior art, the following is a brief introduction to the drawings required for use in the specific implementation or the description of the prior art.
[0028] Figure 1This is the SEM image of Li2B4O7:1mol.%Er prepared in Example 1.
[0029] Figure 2 This is the XRD pattern of Li2B4O7:1mol.%Er prepared in Example 1.
[0030] Figure 3 This is the Raman spectrum of Li2B4O7:1mol.%Er prepared in Example 1.
[0031] Figure 4 This is the photoluminescence spectrum of Li2B4O7:1mol.%Er prepared in Example 1, with an excitation wavelength of 520nm.
[0032] Figure 5 This is the photoluminescence spectrum of Li2B4O7:2mol.%Er prepared in Example 1, with an excitation wavelength of 520nm.
[0033] Figure 6 This is the photoluminescence spectrum of Li2B4O7:3mol.%Er prepared in Example 1, with an excitation wavelength of 520nm. DETAILED DESCRIPTION
[0034] The present invention is described in detail and clearly in conjunction with specific embodiments below. Obviously, the described embodiments are only a part of embodiments of the present invention, rather than all embodiments. The following embodiments are not restrictive, and the protection scope of the present invention cannot be limited by the following embodiments. On the contrary, the purpose of providing these embodiments is to provide a more thorough and comprehensive understanding of the disclosure of the present invention.
[0035] In the present invention, unless otherwise specified, the numerical intervals involved above are considered to be continuous and include the minimum and maximum values of the range, that is, all values between the two. In particular, when the described range is an integer, all integers in the range are included. In addition, when multiple ranges are provided to describe features or characteristics, these ranges can be combined. In other words, all ranges disclosed herein, unless otherwise explicitly stated, should be understood to include any sub-ranges therein.
[0036] In the present invention, the method steps without emphasizing the temperature are generally carried out at normal temperature or room temperature.
[0037] The following are specific embodiments, which are intended to further explain the present invention in detail to help those skilled in the art and researchers to further understand. Any form of modification made within the scope of the claims of this application is within the scope of protection of the claims of this application.
[0038] Example 1
[0039] (1) High-purity lithium carbonate powder and boric acid powder were mixed evenly (the molar ratio of lithium carbonate to boric acid was 1:4), deionized water was added and stirred thoroughly, and the mixture was reacted for 1 hour to obtain a clear and transparent solution A;
[0040] (2) taking a tannic acid solution, adding a certain amount of deionized water, and performing a hydrolysis reaction at room temperature to prepare a solution B;
[0041] (3) Solution B was slowly added to Solution A. After thorough mixing and stirring, tetraethylenepentamine was added to adjust the pH to 10, and erbium oxide powder (molar ratio: Er:Li2B4O7=0.01:1) was added. The mixture was heated at 80°C to prepare a solution C of a certain viscosity.
[0042] (4) Solution C was evenly coated on the substrate by spin coating, and the sample was dried at 200° C. for 1 h. The dried sample was washed twice in anhydrous ethanol, placed in a muffle furnace, and heated to 800° C. at a rate of 3° C. / min, and calcined for 1 h to obtain a rare earth erbium-doped lithium tetraborate film;
[0043] (5) An optically stimulated luminescence dosimeter is made by placing a rare earth erbium-doped lithium tetraborate film in a transparent shell to detect radiation signals.
[0044] The chemical formula of the rare earth erbium doped lithium tetraborate film obtained in this embodiment is Li2B4O7: 1 mol.% Er. Figure 1 , Figure 1 Shown is a SEM image of rare earth erbium-doped lithium tetraborate film, from which it can be seen that the film has good uniformity and high crystallinity. Figure 2 and Figure 3 They are the XRD pattern and Raman spectrum of rare earth erbium doped lithium tetraborate film, indicating that it is a rare earth erbium doped lithium tetraborate crystal with higher purity. Figure 4 The photoluminescence spectrum of Li2B4O7: 1mol.% Er is shown with an excitation wavelength of 520nm. It can be seen that in the photoluminescence, there are strong luminescence peaks in the range of 535-560nm.
[0045] Example 2
[0046] (1) High-purity lithium carbonate powder and boric acid powder were mixed evenly (the molar ratio of lithium carbonate to boric acid was 1:4), deionized water was added and stirred thoroughly, and the mixture was reacted for 1 hour to obtain a clear and transparent solution A;
[0047] (2) taking a tannic acid solution, adding a certain amount of deionized water, and performing a hydrolysis reaction at room temperature to prepare a solution B;
[0048] (3) Solution B was slowly added to Solution A. After thorough mixing and stirring, tetraethylenepentamine was added to adjust the pH to 10, and erbium oxide powder (molar ratio: Er:Li2B4O7=0.02:1) was added. The mixture was heated at 80°C to prepare a solution C of a certain viscosity.
[0049] (4) Solution C was evenly coated on the substrate by spin coating, and the sample was dried at 200° C. for 1 h. The dried sample was washed twice in anhydrous ethanol, placed in a muffle furnace, and heated to 800° C. at a rate of 3° C. / min, and calcined for 1 h to obtain a rare earth erbium-doped lithium tetraborate film;
[0050] (5) An optically stimulated luminescence dosimeter is made by placing a rare earth erbium-doped lithium tetraborate film in a transparent shell to detect radiation signals.
[0051] The chemical formula of the rare earth erbium-doped lithium tetraborate film obtained in this embodiment is Li2B4O7: 2 mol.% Er. Figure 5 The photoluminescence spectrum of Li2B4O7: 2mol.% Er is shown with an excitation wavelength of 520nm. It can be seen that in the photoluminescence, there are strong luminescence peaks in the range of 530-880nm.
[0052] Example 3
[0053] (1) High-purity lithium carbonate powder and boric acid powder were mixed evenly (the molar ratio of lithium carbonate to boric acid was 1:4), deionized water was added and stirred thoroughly, and the mixture was reacted for 1 hour to obtain a clear and transparent solution A;
[0054] (2) taking a tannic acid solution, adding a certain amount of deionized water, and performing a hydrolysis reaction at room temperature to prepare a solution B;
[0055] (3) Solution B was slowly added to Solution A. After thorough mixing and stirring, tetraethylenepentamine was added to adjust the pH to 10, and erbium oxide powder (molar ratio: Er:Li2B4O7=0.03:1) was added. The mixture was heated at 80°C to prepare a solution C of a certain viscosity.
[0056] (4) Solution C was evenly coated on the substrate by spin coating, and the sample was dried at 200° C. for 1 h. The dried sample was washed twice in anhydrous ethanol, placed in a muffle furnace, and heated to 800° C. at a rate of 3° C. / min, and calcined for 1 h to obtain a rare earth erbium-doped lithium tetraborate film;
[0057] (5) An optically stimulated luminescence dosimeter is made by placing a rare earth erbium-doped lithium tetraborate film in a transparent shell to detect radiation signals.
[0058] The chemical formula of the rare earth erbium-doped lithium tetraborate film obtained in this embodiment is Li2B4O7: 3 mol.% Er. Figure 6The photoluminescence spectrum of Li2B4O7: 1mol.% Er is shown with an excitation wavelength of 520nm. It can be seen that in the photoluminescence, there are strong luminescence peaks in the range of 530-580nm.
Claims
1. A rare earth erbium doped lithium tetraborate thin film optically stimulated luminescence dosimeter and a preparation method thereof, characterized in that: The preparation of rare earth erbium doped lithium tetraborate thin film includes the following steps: (1) High-purity lithium carbonate powder and boric acid powder are mixed evenly, and deionized water is added and stirred thoroughly to obtain a clear and transparent solution A; (2) taking a tannic acid solution, adding a certain amount of deionized water, and performing a hydrolysis reaction at room temperature to prepare a solution B; (3) Solution B is slowly added to Solution A, and after thorough mixing and stirring, tetraethylenepentamine is added to adjust the pH value, and erbium oxide powder is added to prepare a solution C of a certain viscosity; (4) evenly coating solution C on a substrate by spin coating, drying the sample, and annealing the sample in a muffle furnace to obtain a rare earth erbium-doped lithium tetraborate thin film; (5) The optically stimulated luminescence dosimeter includes a transparent shell and a rare earth erbium-doped lithium tetraborate film for detecting radiation signals. The transparent shell is provided with a light-through hole corresponding to the light irradiated onto the dosage sheet.
2. The optically stimulated luminescence dosimeter of rare earth erbium doped lithium tetraborate thin film and the preparation method thereof according to claim 1, characterized in that: In step (1), the molar ratio of lithium carbonate to boric acid is 1:4-4.
8.
3. The optically stimulated luminescence dosimeter of rare earth erbium doped lithium tetraborate thin film and the preparation method thereof according to claim 1, characterized in that: In step (1), the reaction time is 0.5-5h.
4. The optically stimulated luminescence dosimeter of rare earth erbium doped lithium tetraborate thin film and the preparation method thereof according to claim 1, characterized in that: In step (3), solution C is heated at 50-100° C. to have a certain viscosity.
5. The optically stimulated luminescence dosimeter of rare earth erbium doped lithium tetraborate thin film and the preparation method thereof according to claim 1, characterized in that: In step (3), the molar ratio of erbium oxide to lithium tetraborate is controlled to Er:Li2B4O7=0.005-0.05:
1.
6. The optically stimulated luminescence dosimeter of rare earth erbium doped lithium tetraborate thin film and the preparation method thereof according to claim 1, characterized in that: In step (3), pH = 9-11.
7. The optically stimulated luminescence dosimeter of rare earth erbium doped lithium tetraborate thin film and the preparation method thereof according to claim 1, characterized in that: In step (4), the drying temperature is 100-200°C and the annealing temperature is 500-800°C.
8. The optically stimulated luminescence dosimeter of rare earth erbium doped lithium tetraborate thin film and the preparation method thereof according to claim 1, characterized in that: In step (4), the drying time is 0.5-5h, and the annealing time is 0.5-5h.
9. The optically stimulated luminescence dosimeter of rare earth erbium doped lithium tetraborate thin film and the preparation method thereof according to claim 1, characterized in that: In step (4), the dried sample is washed 2-3 times in anhydrous ethanol.
10. The optically stimulated luminescence dosimeter of rare earth erbium doped lithium tetraborate thin film and the preparation method thereof according to claim 1, characterized in that: In step (4), the heating rate during annealing is 2-9°C / min.