A lead-free glass ceramic scintillator and its preparation method and application

Abstract

The present invention belongs to the field of optical functional materials and detection technology, and discloses a non-lead glass ceramic scintillator and a preparation method thereof. (1) The components of the precursor glass are SiO2-Na2CO3-Al2O3-CaCO3-NaF-LuF3-GdF3-CeF3; (2) Using the glass components in step (1), SiO2, Na2CO3, Al2O3, CaCO3, NaF, LuF3, GdF3, CeF3 and other raw materials are accurately weighed, and an appropriate amount of Al powder is added, and the mixture is fully mixed and then transferred into an alumina crucible; (3) The precursor glass in step (2) is prepared by a melt quenching method, and the melting temperature is 1350-1450°C and the temperature is kept for 1 to 2 hours; (4) The precursor glass obtained in step (3) is subjected to a crystallization treatment to obtain a Na5Lu 9‑x Gd x F 32 :Ce 3+ The scintillator preparation method of the present invention is simple, the preparation cycle is short, the raw materials used are low in cost and do not contain lead, and are very suitable for large-scale industrial production. The luminescent center of the scintillator in the present invention is Ce 3+ ions, Al powder addition can effectively inhibit Ce 3+ At the same time, energy is easily transferred from Gd ions to Ce ions, improving luminescence efficiency.

Description

Technical Field

[0001] The present invention relates to the field of photoelectric functional materials and detection technology, and specifically to a method for preparing a lead-free glass ceramic scintillator and its application in the field of X-ray detection. Background Art

[0002] Scintillators are widely used in fields such as medical imaging, industrial non-destructive testing, and safety inspection. The continuous progress of society and science has put forward higher requirements for scintillators, including high stability, high spatial resolution, excellent radioluminescence, reasonable decay time, and low-cost production. Traditional single crystal scintillators such as BGO, CsI:Tl, and YAG:Ce have disadvantages such as long preparation cycle, high cost, and inflexible device processability, which limit their further application. Perovskite scintillators are unstable in harsh environments such as high temperature, high humidity, and high-energy x-ray irradiation, as well as the disadvantage of lead, which increases the cost of their actual utilization. Therefore, researchers are committed to developing a scintillator that has the advantages of the above materials and overcomes their disadvantages.

[0003] A scintillator is a material that, when exposed to ionizing radiation, converts the absorbed radiation energy into visible or ultraviolet light. This light can be detected and measured by detectors (such as photomultiplier tubes or solid-state photodetectors), enabling the location and quantification of the radiation source. Scintillators have a wide range of applications in medical imaging, industrial nondestructive testing, and safety inspections. However, current scintillator technology has some major drawbacks and technical issues that need to be addressed urgently:

[0004] 1. Cost and preparation cycle: Traditional single crystal scintillators (such as BGO, CsI:Tl and YAG:Ce) have a long preparation cycle and high cost, which hinders their large-scale application and promotion.

[0005] 2. Stability issues: Perovskite scintillators are unstable in harsh environments such as high temperature, high humidity and high-energy x-ray irradiation, which limits their application in some harsh environments.

[0006] 3. Environmental issues: Perovskite scintillators contain lead, a harmful heavy metal that can impact the environment and human health. Therefore, it is necessary to find alternative materials that are lead-free or contain low amounts of lead.

[0007] 4. Processability: The device processability of traditional single crystal scintillators is not flexible, which to some extent limits the design of their shape and size, and thus affects their application in different fields.

[0008] 5. Performance parameters: such as high stability, high spatial resolution, excellent radioluminescence, reasonable decay time, etc. These are the basic requirements for scintillator performance, but current scintillator technology cannot meet these requirements well.

[0009] Therefore, researchers need to develop a scintillator that has the advantages of the above materials while overcoming their disadvantages in order to meet the higher requirements of scintillators brought about by the continuous progress of society and science. Summary of the Invention

[0010] In view of the problems and shortcomings in the prior art, the present invention provides a lead-free glass-ceramic scintillator, a preparation method thereof, and applications in the field of X-ray detection.

[0011] In order to achieve the above technical objectives, a lead-free glass-ceramic scintillator is characterized in that the molar ratios of its components are: SiO2: 35~55mol%, Na2CO3: 5~15mol%, Al2O3: 10~20mol%, CaCO3: 2~10mol%, NaF: 2~10mol%, LuF3: 3~15mol%, GdF3: 0~10mol%, CeF3: 0~5mol%.

[0012] Furthermore, Na5Lu was precipitated from the glass matrix. 9-x Gd x F 32 :Ce 3+ of microcrystals.

[0013] The present invention also provides a method for preparing a lead-free glass-ceramic scintillator, comprising the following steps:

[0014] (1) The composition of the precursor glass is SiO2-Na2CO3-Al2O3-CaCO3-NaF-LuF3-GdF3-CeF3;

[0015] (2) Using the glass components in step (1), accurately weigh SiO2, Na2CO3, Al2O3, CaCO3, NaF, LuF3, GdF3, CeF3 and other raw materials, add appropriate amount of Al powder, mix thoroughly and transfer into an alumina crucible;

[0016] (3) preparing the precursor glass in step (2) by melt quenching method, with the melting temperature being 1350-1450° C. and keeping the temperature for 1-2 hours;

[0017] (4) The precursor glass obtained in step (3) is crystallized to obtain a glass having the chemical formula Na5Lu 9-x Gd x F 32 :Ce 3+ of glass-ceramics.

[0018] Furthermore, in the glass system in step (1), the molar ratio of each component is SiO2: 35-55mol%, Na2CO3: 5-15mol%, Al2O3: 10-20mol%, CaCO3: 2-10mol%, NaF: 2-10mol%, LuF3: 3-15mol%, GdF3: 0-10mol%, and CeF3: 0-5mol%.

[0019] Furthermore, as a preferred embodiment of the present invention, the addition of reducing agent Al powder can effectively inhibit Ce 3+ To Ce 4 + reaction, minimizing Ce 4+ content to ensure luminous efficiency.

[0020] Furthermore, the addition amount of the Al powder in step (2) is 0 to 10 mol%.

[0021] Furthermore, the crystallization conditions in step (4) are: keeping the temperature at 400-500°C for 1-4 hours, and the heating rate is 3-15°C / min.

[0022] Furthermore, the microcrystals obtained after the heat treatment in step (4) have the chemical formula Na5Lu 9-x Gd x F 32 :Ce 3+ According to the different contents of LuF3 and GdF3 and the differences in crystallization temperature and time, 0 <x<9。

[0023] The present invention also provides an application of a lead-free glass ceramic scintillator in X-ray imaging and luminescence detection.

[0024] In combination with the above technical solutions and the technical problems solved, the advantages and positive effects of the technical solutions to be protected by the present invention are as follows:

[0025] First, the scintillator preparation method of the present invention is simple, with a short preparation cycle. The raw materials used are low-cost and lead-free, making it very suitable for large-scale industrial production. Furthermore, the scintillator material is environmentally friendly and has low recycling or disposal costs. Thanks to the protection of glass, the scintillator of the present invention can withstand corrosion from water, oxygen, moisture, and the like, extending its application range. The scintillator of the present invention maintains its initial state under high-energy radiation, offering greater stability and practical applicability. Furthermore, the non-lead glass ceramic scintillator of the present invention has a simple preparation method, low raw material costs, and a short preparation cycle, making it very suitable for industrial production.

[0026] Second, the lead-free glass ceramic scintillator of the present invention is prepared by precipitating Na5Lu in a precursor glass matrix. 9-x Gd xF 32 :Ce 3+ On the one hand, the precipitated crystals are protected by the glass matrix and can withstand high energy X-ray radiation. On the other hand, the luminescent center of the scintillator in the present invention is Ce. 3+ ions, Al powder addition can effectively inhibit Ce 3+ ions. At the same time, Gd 3+ The ground state is very close to Ce 3+ The 5d energy level of the scintillator can easily transfer energy from the Gd ions to the Ce ions, thereby improving the luminescence efficiency. This makes the fluorescence intensity of the scintillator of the present invention much higher than that of traditional single crystal scintillators such as BGO.

[0027] Third, as auxiliary evidence for the inventiveness of the claims of the present invention, it is also reflected in the following important aspects:

[0028] (1) The expected benefits and commercial value of the technical solution of the present invention after transformation are:

[0029] The present invention relates to a non-lead glass ceramic scintillator and a preparation method. The scintillator industry has a mature application market, including security inspection, hospitals, scientific research and factory testing. Currently, scintillators are mainly traditional crystals such as BGO and CsI:Tl, which have high production costs and long cycles. The non-lead glass ceramic scintillator in the present invention has low R&D investment and production costs, which is a huge advantage from the perspective of product promotion. The scintillator of the present invention can withstand high-dose X-ray radiation, has high stability, and has better scintillation performance than traditional scintillators such as BGO. It has a long service life and has high commercial value and practicality from a performance perspective.

[0030] (2) The technical solution of the present invention fills the technical gap in the industry at home and abroad:

[0031] Traditional crystal scintillators are the mainstay of commercial scintillators, but they lack performance and are expensive. New lead-containing scintillators offer cost and performance advantages, but lead is unfriendly to the environment and the human body. Typically, the scintillation performance of new lead-free materials is far inferior to that of traditional crystals. The technical solution of the present invention addresses the practical application challenges of new lead-free scintillators. Compared to traditional crystal scintillators, the lead-free glass-ceramic scintillator of the present invention not only reduces costs and improves scintillation performance, but also eliminates the environmental and human hazards of lead.

[0032] Fourthly, the present invention provides a new component ratio of a lead-free glass-ceramic scintillator, which may lead to optimized performance, such as higher light yield and shorter decay time.

[0033] The present invention may improve the optical properties of the scintillator by precipitating specific microcrystals in the glass matrix, so that the scintillator has higher energy resolution.

[0034] The present invention provides a specific preparation method for the lead-free glass ceramic scintillator, including the components of the precursor glass, the preparation of the precursor glass by melt quenching method, and the steps of crystallization treatment, which may lead to the optimization of the performance of the scintillator.

[0035] The present invention clarifies the amount of Al powder added during the preparation process, which may affect the light yield and decay time of the final product.

[0036] The present invention clarifies the specific conditions of the crystallization treatment, which may affect the size and shape of the precipitated microcrystals, thereby affecting the performance of the scintillator.

[0037] The present invention clarifies the chemical formula of the obtained microcrystals, which may be helpful for understanding and optimizing the performance of scintillators.

[0038] The present invention clarifies that the mixing process of raw materials involves thorough mixing to ensure uniformity, which may help improve the uniformity and performance of the final product.

[0039] The present invention clarifies that a certain holding time is involved in the melt quenching process of the precursor glass to ensure complete melting, which may help to improve the purity and performance of the final product. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] Figure 1 This is a TEM image of a lead-free glass-ceramic scintillator prepared in an embodiment of the present invention.

[0041] Figure 2 This is the X-ray diffraction pattern of the lead-free glass-ceramic scintillator prepared in an embodiment of the present invention.

[0042] Figure 3 This is a comparison chart of the photoluminescence and X-ray radiation luminescence of the lead-free glass-ceramic scintillator prepared in an embodiment of the present invention.

[0043] Figure 4 The fluorescence lifetime of the lead-free glass-ceramic scintillator prepared in the embodiment of the present invention.

[0044] Figure 5 The present invention provides an application of the lead-free glass-ceramic scintillator prepared in accordance with an embodiment of the present invention in the field of X-ray detection.

[0045] Figure 6 This is a comparison chart of the X-ray excited luminescence spectra of the lead-free glass ceramic scintillator prepared in an embodiment of the present invention and the commercial BGO crystal.

[0046] Figure 7 Transmission spectra of the lead-free glass-ceramic scintillator prepared according to the embodiment of the present invention under different X-ray radiation intensities. DETAILED DESCRIPTION

[0047] The following are examples of the present invention. It should be noted that the examples are provided to provide a more detailed description of certain aspects, features, and embodiments of the present invention and are not intended to limit the scope of the present invention. The present invention is not limited to the following examples. The methods described are conventional methods unless otherwise specified.

[0048] In an embodiment of the present invention, a method for preparing a lead-free glass-ceramic scintillator comprises the following steps:

[0049] (1) The components of the precursor glass are SiO2-Na2CO3-Al2O3-CaCO3-NaF-LuF3-GdF3-CeF3. The molar ratios of the components in the precursor glass are: SiO2: 35-55 mol%, Na2CO3: 5-15 mol%, Al2O3: 10-20 mol%, CaCO3: 2-10 mol%, NaF: 2-10 mol%, LuF3: 3-15 mol%, GdF3: 0-10 mol%, and CeF3: 0-5 mol%.

[0050] (2) Using the glass components in step (1), accurately weigh SiO2, Na2CO3, Al2O3, CaCO3, NaF, LuF3, GdF3, CeF3 and other raw materials, add 0-10 mol% of Al powder, mix thoroughly and transfer into an alumina crucible.

[0051] (3) The precursor glass is prepared by melt quenching method in step (2), with the melting temperature being 1350-1450° C. and being kept warm for 1 to 2 hours.

[0052] (4) The precursor glass obtained in step (3) is subjected to crystallization treatment. The crystallization conditions are: keeping the temperature at 400-500°C for 1-4 hours and heating at a rate of 3-15°C / min. The chemical formula is Na5Lu 9-x Gd x F 32 :Ce 3+ of glass-ceramics, of which 0 <x<9。

[0053] The following is described with reference to preferred specific embodiments.

[0054] A method for preparing a lead-free glass ceramic scintillator comprises the following steps:

[0055] Step 1: The precursor glass comprises SiO2-Na2CO3-Al2O3-CaCO3-NaF-LuF3-GdF3-CeF3. The preferred molar ratios of the components in the precursor glass are: SiO2: 45 mol%, Na2CO3: 10 mol%, Al2O3: 15 mol%, CaCO3: 4 mol%, NaF: 6 mol%, LuF3: 5 mol%, GdF3: 3 mol%, and CeF3: 1 mol%.

[0056] Step 2: Using the glass components in step 1, accurately weigh SiO2, Na2CO3, Al2O3, CaCO3, NaF, LuF3, GdF3, CeF3 and other raw materials, and add 2.5 mol% of Al powder, mix thoroughly in a mortar for 1 hour, and then transfer the mixed powder into an alumina crucible.

[0057] Step 3: Prepare the precursor glass using the melt quenching method in Step 2 at a melt temperature of 1400°C for 1 hour. Immediately thereafter, pour the melt onto a copper plate controlled at 300°C. Simultaneously, pressurize the melt with another copper plate, causing the melt to rapidly form glass between the plates.

[0058] Step 4: The precursor glass obtained in step 3 is cut into a shape with a thickness of 2 mm and polished, and then crystallized. The crystallization conditions are 450℃ for 2 hours and a heating rate of 5℃ / min. The final chemical formula is Na5Lu 9-x Gd x F 32 :Ce 3+ of glass-ceramics.

[0059] After testing, Na5Lu in glass 9-x Gd x F 32 :Ce 3+ The average size of the crystallites is 16 nm. Figure 1 shown. Figure 2 The X-ray diffraction pattern of the lead-free glass-ceramic scintillator shown shows that the glass-ceramic has a very good crystalline phase. Figure 3 This is a comparison chart of luminescence and photoluminescence under X-ray radiation. The wavelength of the excitation light of the photoluminescence spectrum is 330nm. Under this excitation light, the microcrystalline glass shows good fluorescence, and the luminescence peak is at 383nm. Under X-ray irradiation, the microcrystalline glass also shows a good luminescence curve, which is basically consistent with the photoluminescence curve, indicating that the luminescence comes from Ce 3+ Luminous center. Figure 4 Na5Lu 9-x Gd x F 32 :Ce 3+The fluorescence lifetime of glass-ceramics was 52.7 nanoseconds, which is much lower than that of rare earth ions (Tb 3+ 、Eu 3+ )The lifetime of the doped glass scintillator is short (milliseconds), which is beneficial for X-ray imaging.

[0060] like Figure 5 As shown, the lead-free glass ceramic can be used as a scintillator element in the field of X-ray detection and imaging. The structure of the spring and chip in the capsule can be clearly seen. Importantly, the spatial resolution of the scintillator of the present invention reaches 14lp / mm, which is higher than many perovskite and BGO scintillators. The results show that the scintillator containing Na5Lu 9-x Gd x F 32 :Ce 3+ Microcrystalline scintillators have greater X-ray imaging advantages and can be used to identify capsule springs and circuit boards.

[0061] Using commercial BGO crystals of the same thickness as a comparative example, the X-ray (tube voltage 50kV, tube current 200μA) irradiation was tested to compare the performance of the crystals with those of Na5Lu. 9-x Gd x F 32 :Ce 3+ The sparkle and luminescence of glass-ceramic. Figure 6 As shown in FIG, the luminous intensity of the glass-ceramic has exceeded that of the BGO crystal, and the integrated intensity has reached 126% of that of the BGO crystal. This comparison shows that the lead-free glass-ceramic scintillator provided by the present invention has excellent scintillation performance.

[0062] like Figure 7 As shown, Na5Lu was tested 9-x Gd x F 32 :Ce 3+ The transmittance of the glass-ceramic scintillator under different radiation intensities was measured. The results showed that even under high-intensity radiation, the transmittance of the lead-free glass-ceramic scintillator of the present invention remained essentially unchanged compared to its initial transmittance. This demonstrates that the lead-free glass-ceramic scintillator provided by the present invention has excellent stability and is suitable for commercial development.

[0063] Example 1:

[0064] The present invention provides a method for preparing a lead-free glass ceramic scintillator, the specific steps of which are as follows:

[0065] (1) Accurately weigh various raw materials according to the molar ratio of SiO2: 40 mol%, Na2CO3: 12 mol%, Al2O3: 20 mol%, CaCO3: 10 mol%, NaF: 8 mol%, LuF3: 3 mol%, GdF3: 6 mol%, and CeF3: 1 mol%, and add an appropriate amount of Al powder;

[0066] (2) The above raw materials are fully mixed and transferred into an alumina crucible;

[0067] (3) Place the crucible in a muffle furnace and keep it at 1375°C for 1 hour;

[0068] (4) After the heat preservation is completed, the crucible is taken out and immediately quenched with cold water to obtain a precursor glass;

[0069] (5) The precursor glass was placed at 420°C for 2 hours for crystallization to obtain a chemical formula of Na5Lu 9- x Gd x F 32 :Ce 3+ Glass-ceramics, where x=8 is the main crystalline phase.

[0070] Example 2:

[0071] The present invention provides a method for preparing a lead-free glass ceramic scintillator, the specific steps of which are as follows:

[0072] (1) Accurately weigh various raw materials according to the molar ratio of SiO2: 45 mol%, Na2CO3: 8 mol%, Al2O3: 18 mol%, CaCO3: 7 mol%, NaF: 6 mol%, LuF3: 10 mol%, GdF3: 4 mol%, and CeF3: 2 mol%, and add an appropriate amount of Al powder;

[0073] (2) The above raw materials are fully mixed and transferred into an alumina crucible;

[0074] (3) Place the crucible in a muffle furnace and keep it at 1400°C for 1.5 hours;

[0075] (4) After the heat preservation is completed, the crucible is taken out and immediately quenched with cold water to obtain a precursor glass;

[0076] (5) The precursor glass was placed at 450°C for 3 hours for crystallization to obtain a chemical formula of Na5Lu 9- x Gd x F 32 :Ce 3+ Glass-ceramics, where x=6 is the main crystalline phase.

[0077] The above are only two specific embodiments of the present invention, and the present invention also includes other embodiments. The lead-free glass-ceramic scintillator of the present invention has good optical and scintillation properties and is suitable for medical imaging, nuclear detection, high-energy physics experiments and other fields.

[0078] The above is only a specific embodiment for better understanding the present invention, and the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can make equivalent replacements or changes based on the technical solution and inventive concept of the present invention within the technical scope disclosed by the present invention, and they should be covered by the protection scope of the present invention.

Claims

1. A lead-free glass ceramic scintillator, characterized in that: The molar ratios of its components are: SiO2: 35~55mol%, Na2CO3: 5~15mol%, Al2O3: 10~20mol%, CaCO3: 2~10mol%, NaF: 2~10mol%, LuF3: 3~15mol%, GdF3: 0~10mol%, CeF3: 0~5mol%; The chemical formula of Na5Lu precipitated from the glass matrix 9-x Gd x F 32 :Ce 3+ of microcrystals; The preparation method of lead-free glass ceramics comprises the following steps: (1) The components of the precursor glass are SiO2: 35~55mol%, Na2CO3: 5~15mol%, Al2O3: 10~20mol%, CaCO3: 2~10mol%, NaF: 2~10mol%, LuF3: 3~15mol%, GdF3: 0~10mol%, CeF3: 0~5mol%; (2) Using the glass components in step (1), accurately weigh SiO2, Na2CO3, Al2O3, CaCO3, NaF, LuF3, GdF3, and CeF3 raw materials, add Al powder, mix thoroughly, and transfer into an alumina crucible; (3) preparing the precursor glass by melt quenching method in step (2), with the melting temperature of 1350-1450°C and keeping the temperature for 1-2 hours; (4) The precursor glass obtained in step (3) is crystallized to obtain a glass with the chemical formula Na5Lu 9-x Gd x F 32 :Ce 3+ of glass-ceramics, where 0< x <9.

2. The lead-free glass-ceramic scintillator according to claim 1, characterized in that: The addition amount of Al powder is 0~10mol%.

3. The lead-free glass-ceramic scintillator according to claim 1, characterized in that: The crystallization conditions are 400-500°C for 1-4 hours.

Images