Imaging device based on hexagonal boron nitride neutron imaging plate and preparation method thereof

Abstract

The invention discloses an imaging device based on a hexagonal boron nitride neutron imaging plate and a preparation method thereof, and the device comprises a neutron source, a collimator, a neutron imaging plate, a first reflector and an imaging device, and also comprises an excitation source which is used for emitting laser; the neutron imaging plate is an h-BN imaging plate and comprises a substrate and an h-BN film covering the substrate. The imaging device is a CCD (Charge Coupled Device) fluorescence imaging device; thermal neutrons emitted by the neutron source irradiate a to-be-detected sample, part of the thermal neutrons penetrate through the to-be-detected sample and then irradiate the h-BN imaging plate, thermal neutron irradiation damage defects occur, photoluminescence is generated under excitation of laser emitted by the laser source, and the photoluminescence is reflected to the CCD fluorescence imaging device through the first reflector to complete imaging of the to-be-detected sample. According to the invention, neutron current detection can be realized according to the boron vacancy defect of h-10BN and by utilizing the photoluminescence characteristic of h-10BN, the gamma sensitivity is low, the device process is simple, and the neutron measurement cost is reduced.

Description

Technical Field

[0001] This invention relates to the field of neutron imaging technology, and in particular to an imaging device based on a hexagonal boron nitride neutron imaging plate and its fabrication method. Background Technology

[0002] Highly efficient neutron measurements are crucial for many fields, including condensed matter physics, neutron logging, nuclear power plant safety monitoring, and radiation environment detection. However, directly and efficiently measuring neutrons has always been a significant challenge. Because neutrons are uncharged and interact weakly with most matter, they do not readily interact with electrons in matter when passing through it, thus failing to directly induce ionization. Therefore, developing advanced neutron measurement techniques and methods is of great importance.

[0003] With 6 Li and 10 Neutron detection technology using solid-state semiconductors of element boron as the substrate is an emerging technology that holds promise for replacing the most widely used method currently. 3 He gas neutron detectors are becoming more efficient detectors. Currently, based on h- 10 Neutron measurements in BN primarily focus on developing charge-collecting neutron detectors. This method requires h- 10 Electrodes are deposited on the surface of BN, and the changes in electrical signals caused by nuclear fission products are collected by the electric field of the electrodes. The neutron dose is then obtained by multiplying the electrical signal intensity by the conversion factor.

[0004] However, the above methods place high demands on device fabrication, requiring processing under precise microscale conditions, which is both technically challenging and costly. Furthermore, the generation and collection of electrical signals are affected by h- 10 BN crystal defects and impurities have a significant impact, therefore this method is effective for h- 10 BN crystals require high quality, while high-quality h- 10 The preparation of BN crystals is not an easy task.

[0005] In existing technologies, chemical vapor deposition or physical vapor deposition methods are commonly used to prepare h- 10 BN, however, both of the above methods require high temperature or high pressure environments, thus placing high demands on the equipment, and both methods require a substrate as h- 10 The growth support for BN thin films, and the h- 10 BN thin films are prone to h- 10 BN film is damaged. Summary of the Invention

[0006] To address the shortcomings of the existing technology, the technical problem to be solved by this invention is: to propose an imaging device based on a hexagonal boron nitride neutron imaging plate and its fabrication method, capable of imaging based on h-10 Boron vacancy defects in boron nanoparticles (BN) are utilized, and their photoluminescence properties are employed to achieve neutron flux detection. This method simplifies device fabrication and reduces the cost of neutron measurement. Furthermore, h- 10 BN crystals are insensitive to gamma rays, and gamma rays have difficulty in inducing h- 10 BN crystals exhibit point defects, providing good n (neutron flux) and γ discrimination capabilities, and h- 10 BN crystals have good stability and are well adaptable to harsh environments such as high temperature, high pressure, and high humidity.

[0007] One technical solution adopted in this invention is: a neutron imaging device, comprising a neutron source, a collimator, a neutron imaging plate, a first reflecting mirror, and an imaging device, and further comprising an excitation source for emitting laser light; the neutron imaging plate is an h-BN imaging plate, comprising a substrate and an h-BN thin film covering the substrate, the h-BN thin film being conformally stacked from h-BN nanosheets; the imaging device is a CCD fluorescence imaging device; thermal neutrons emitted by the neutron source irradiate the sample to be tested after passing through the collimator, and some thermal neutrons penetrate the sample to be tested and irradiate the h-BN imaging plate, being absorbed by the h-BN thin film. 10 B is captured, resulting in thermal neutron irradiation damage defects. Under the excitation of the laser emitted by the laser source, photoluminescence is generated, which is reflected by the first mirror to the CCD fluorescence imaging device to complete the imaging of the sample under test.

[0008] Furthermore, the thickness of the h-BN film is 13±1μm.

[0009] Furthermore, it also includes a filter, which is disposed between the first reflector and the CCD fluorescence imaging device, so that after the photoluminescence of h-BN is reflected on the first reflector, it passes through the filter to remove stray light before entering the CCD fluorescence imaging device.

[0010] Furthermore, the first reflector is a dichroic reflector, used to selectively reflect the photoluminescence of the h-BN imaging plate.

[0011] Furthermore, it also includes a filter, and the first reflector is a dichroic reflector.

[0012] Furthermore, it also includes a second reflector, which is disposed between the laser source and the h-BN imaging plate. The laser emitted by the laser source can be reflected on the surface of the second reflector and then directed toward the h-BN imaging plate.

[0013] Another technical solution adopted in this invention is: providing a method for preparing a neutron imaging plate based on hexagonal boron nitride, the method comprising:

[0014] S1: Mix h-BN powder and urea evenly, pour into a ball mill for ball milling, and obtain a mixture of h-BN nanosheets and urea;

[0015] S2: Add deionized water to the mixture of h-BN nanosheets and urea, stir magnetically, and then place it in a dialysis bag to stand to obtain the initial slurry;

[0016] S3: The initial slurry was placed in a centrifuge to remove water, and h-BN nanosheets were collected from the wall of the centrifuge tube;

[0017] S4: h-BN nanosheets are placed in a polar solvent and dispersed using an ultrasonic instrument to obtain a dispersion.

[0018] S5: Place the dispersion into a vacuum filtration device and filter the dispersion to allow h-BN nanosheets to adhere to the filter membrane and form an h-BN film.

[0019] S6: Transfer the h-BN thin film to the target substrate to obtain the h-BN imaging plate.

[0020] Furthermore, in step S1, the mass ratio of h-BN powder to urea is 4:1, and the size of h-BN powder is 1-2 μm.

[0021] Furthermore, in step S1, the ball milling time is 5 hours and the ball mill speed is 600 rpm.

[0022] Furthermore, in step S2, the dialysis bag has a retention capacity of 6000-10000 Da and a settling time of 3-5 days.

[0023] Furthermore, in step S3, the centrifuge speed is set to 10,000 rpm and the centrifugation time is set to 1 hour.

[0024] Furthermore, in step S4, the polar solvent is one or more of isopropanol, N-methylpyrrolidone, dimethylformamide, dimethyl sulfoxide, and deionized water.

[0025] Furthermore, in step S4, the frequency of the ultrasonic instrument is set to 25MHz, the single dispersion time is set to 3-5s, the interval between single dispersions is set to 1s, and the total dispersion time is set to 30min.

[0026] Furthermore, in step S5, the filter membrane has a pore size of 0.2 μm and is made of PTFE.

[0027] Furthermore, in step S6, before transferring the h-BN film to the target substrate, the filter membrane with the h-BN film attached needs to be immersed in a polar solvent for 3 seconds.

[0028] The imaging device based on a hexagonal boron nitride neutron imaging plate and its preparation method of the present invention have at least the following beneficial effects: The present invention prepares h-BN nanosheets by using h-BN powder and urea, and forms an h-BN thin film on the filter membrane by filtration, and then transfers it to the target substrate by transfer printing. The method does not require the use of vapor deposition, and the process is simple, the equipment requirements are not high, and the cost is low. Attached Figure Description

[0029] The accompanying drawings, which are included to provide a further understanding of this application and form part of this application, illustrate exemplary embodiments and are used to explain this application, but do not constitute an undue limitation of this application. In the drawings:

[0030] Figure 1 This is a schematic diagram of the neutron imaging device of the present invention.

[0031] Figure 2 This is an image of the sample to be tested used in Embodiment 1 of the present invention.

[0032] Figure 3 This is a neutron imaging photograph of the sample to be tested in Embodiment 1 of the present invention.

[0033] Figure 4 This is a flowchart of one embodiment of the method for preparing a neutron imaging plate based on hexagonal boron nitride according to the present invention.

[0034] Figure 5 This is a SEM image of the h-BN film prepared in Example 2 of the present invention.

[0035] Figure 6 This is a SEM cross-sectional image of the h-BN thin film prepared in Example 2 of the present invention.

[0036] Figure 7 The image shows the XRD pattern of the h-BN thin film prepared in Example 2 of this invention.

[0037] Figure 8 This is a Raman diagram of the h-BN thin film prepared in Example 2 of the present invention.

[0038] Figure 9 This is an optical microscope image of the h-BN thin film prepared in Example 2 of the present invention.

[0039] Figure 10 This is a digital photograph of the h-BN thin film prepared in Example 2 of the present invention.

[0040] Figure Labels

[0041] Neutron source-1; Collimator-2; Sample to be tested-3; h-BN imaging plate-4; First reflector-5; Second reflector-6; Laser source-7; Filter-8; CCD fluorescence imaging device-9. Detailed Implementation

[0042] To make the technical points of the present invention clearer, the following will provide further explanation in conjunction with specific embodiments. The embodiments are implemented under the premise of the technical solution of the present invention, and detailed implementation methods and specific operation processes are given. However, the protection scope of the present invention is not limited to the following examples.

[0043] Example 1

[0044] Please see Figure 1 This is a schematic diagram of the neutron imaging device of the present invention. The neutron imaging device includes a neutron source 1, a collimator 2, a neutron imaging plate, a first reflecting mirror 5, and an imaging device. The neutron imaging plate is an h-BN imaging plate 4, comprising a substrate and an h-BN thin film covering the substrate. The h-BN thin film is conformally stacked from h-BN nanosheets. The imaging device is a CCD fluorescence imaging device 9. Thermal neutrons emitted by the neutron source 1 irradiate the sample 3 to be tested after passing through the collimator 2. Some thermal neutrons penetrate the sample 3 to irradiate the h-BN imaging plate 4 and are then absorbed by the h-BN thin film. 10 B-B is captured, resulting in thermal neutron irradiation damage defects. Excitation by the laser emitted from the laser source 7 produces photoluminescence, which is reflected by the first mirror 5 to the CCD fluorescence imaging device 9 to complete the imaging of the sample 3. Furthermore, the aforementioned h-BN thin film is conformally stacked from h-BN nanosheets, with a thickness of 13±1 μm.

[0045] To avoid direct illumination of the laser source 7 onto the h-BN imaging plate 4, which would cause optical path cross-interference between the laser and the photoluminescence of the h-BN imaging plate 4, the second reflector 6 can be used to fold the laser optical path to precisely control the laser optical path and the irradiation position.

[0046] To improve imaging quality, a filter 8 can be placed between the first reflector 5 and the CCD fluorescence imaging device 9. This allows the photoluminescence emitted by the h-BN imaging plate 4 to be reflected by the first reflector 5, filtered by the filter 8 to remove stray light, and then enter the CCD fluorescence imaging device 9, thus improving image quality. Alternatively, the first reflector 5 can be configured as a dichroic reflector to selectively reflect the laser-excited photoluminescence of the h-BN imaging plate 4 and absorb stray light of other wavelengths, thereby improving image quality.

[0047] Of course, setting the first reflecting mirror 5 as a dichroic reflecting mirror and simultaneously setting the filter 8 can maximize the improvement of image quality.

[0048] The principle of this device is as follows:

[0049] Thermal neutrons emitted by neutron source 1 are collimated by collimator 2 and then irradiated onto sample 3. Due to the interaction of neutrons with different substances, they are more sensitive to low-Z elements. Some neutrons will be absorbed, while others will pass through sample 3 and irradiate onto h-BN imaging plate 4, thus completing the information acquisition.

[0050] When thermal neutrons (0.025 eV) are detected by the h-BN imaging plate 4 10 After B is absorbed, the following occurs: 10 B,(n,α) 7 The Li reaction, which produces 7Li particles in the excited state, has a branching ratio of 94%, and its nuclear reaction formula is as follows:

[0051]

[0052] Genesis in the ground state 7 The branching ratio of Li particles is 6%, the average reaction energy is 2.34 MeV, and its nuclear reaction formula is:

[0053]

[0054] Furthermore, this energy causes some boron atoms to be knocked out of their positions, creating vacancies in the crystal lattice. The vacancies left by the displaced boron atoms capture additional electrons, becoming... The defect is a negatively charged boron vacancy. The defect consists of a missing boron atom and three equivalent nitrogen atoms as nearest neighbors. This defect forms a spin triplet state (m = 0, m = ±1), characterized by a zero-field splitting value D = 3.5 GHz. It can be excited by a 532 nm laser to induce significant near-infrared photoluminescence. Therefore, the laser source 7 in this embodiment should be a 532 nm laser source.

[0055] Furthermore, the laser source 7 emits a 532nm laser beam, which is reflected by a mirror and projected onto the h-BN imaging plate 4. The defects emit defect fluorescence, which can be imaged on the CCD fluorescent screen in the CCD fluorescence imaging device 9. A dichroic mirror 5 is placed between the h-BN imaging plate 4 and the CCD fluorescence imaging device 9 to distinguish between the laser source and the defect emission source. A filter 8 is placed in front of the CCD fluorescence imaging device 9 to filter the light scattered by the system. This completes the information reading process.

[0056] Please see Figure 2 The image shown is of sample 3 used in the device test of this embodiment. The stripe spacing is 40μm and the stripe width is 15μm, 25μm, 30μm, 35μm and 40μm. Figure 3 To achieve this through the apparatus of this embodiment, at thermal neutron source 1, a 1×1015 The irradiation dose of ions, and the images obtained.

[0057] Example 2

[0058] Please see Figure 4 This is a flowchart illustrating an embodiment of the method for fabricating a neutron imaging plate based on hexagonal boron nitride according to the present invention. Specifically, this method may include:

[0059] 1. Weigh 5g of h-BN powder and mix it evenly with 20g of urea granules, then pour the mixture into a ball mill. The particle size of h-BN is 1-2μm. In this step, the ball mill speed can be set to 600rpm and the working time can be set to 5 hours. During the ball milling process, open the lid every hour to check and observe the powder settling to the bottom and adhering to the inner wall of the ball mill jar, and stir evenly with a stirring rod.

[0060] The purpose of this step is to allow urea crystals to penetrate the interlayer of h-BN particles through ball milling, weakening the interlayer forces and causing functionalization, thereby enabling the exfoliation of h-BN nanosheet monolayers from the h-BN particles. The selected h-BN powder particles have a size of 1–2 μm to balance the exfoliation difficulty and monolayer yield. When the h-BN powder particles are smaller than 1 μm, the interlayer forces are weak due to their small size, making the resulting h-BN nanosheet monolayers easy to exfoliate, but the obtained monolayers are prone to defects. Conversely, when the h-BN powder particles are larger than 2 μm, the interlayer forces are strong due to their large size, making it extremely difficult to exfoliate h-BN nanosheet monolayers. Therefore, to balance the exfoliation difficulty and monolayer yield, h-BN powder with a particle size of 1–2 μm is selected.

[0061] 2. Add 500 mL of deionized water to the mixture of h-BN nanosheets and urea obtained after ball milling, filter out the zirconium beads, and stir the slurry evenly using a magnetic stirrer before placing it in a dialysis bag and letting it stand for four days. Specifically, the dialysis procedure in this step involves adding 10 mL of the initial slurry to each dialysis bag, dialyzing in deionized water for 4 days, changing the external deionized water every 24 hours, and using a dialysis bag with a molecular weight cutoff of 8000D.

[0062] The purpose of this step is to first remove residual milled beads (zirconium beads) from the mixture of h-BN nanosheets and urea through filtration, and then use a dialysis bag to remove urea molecules from the h-BN particles and urea mixture, thereby obtaining an initial slurry containing h-BN nanosheets. During dialysis, since the molecular weight of urea is much smaller than the molecular weight cutoff of the dialysis bag, urea molecules can freely pass through the dialysis bag. Therefore, it can be considered that the molecular weight cutoff of the dialysis bag is directly proportional to the dialysis efficiency of urea molecules. That is, to improve the dialysis rate of urea, a dialysis bag with a large molecular weight cutoff can be selected. However, an excessively large molecular weight cutoff will cause the loss of h-BN nanosheets. Therefore, to balance the dialysis rate of urea and the loss of h-BN nanosheets, this embodiment uses a dialysis bag with a molecular weight cutoff of 8000D. After 4 days of dialysis, the loss of h-BN nanosheets is less than 5%.

[0063] 3. Weigh 150g of the initial slurry and divide it into three equal portions. Place each portion in a centrifuge and set the centrifuge speed to 10,000 rpm for one hour. The purpose of this step is to allow the h-BN nanosheets dispersed in the initial slurry to adhere to the centrifuge tube wall through centrifugation, thereby collecting the h-BN nanosheets. After one hour of centrifugation, the h-BN nanosheets will adhere to the centrifuge tube wall. Pour out the deionized water. Since the larger h-BN nanosheets will sink to the bottom, collect the upper portion of h-BN nanosheets with the largest aspect ratio.

[0064] 4. Add 50 mL of isopropanol (IPA) to the collected h-BN nanosheets and disperse them using an ultrasonic device. The ultrasonic frequency is 25 MHz, the single dispersion time is set to 3-5 seconds, and the interval time is 1 second; the dispersion time is 30 minutes. In this step, in addition to isopropanol (IPA) as a polar solvent, other polar solvents that can be used include isopropanol (IPA), N-methylpyrrolidone (NMP), dimethylformamide (DMF), dimethyl sulfoxide (DMSO), or deionized water, preferably dimethylformamide (DMF) or isopropanol (IPA).

[0065] 5. Pour the dispersion into a vacuum filtration device and perform vacuum filtration to allow h-BN nanosheets to adhere to the filter membrane and form an h-BN film. Continuously observe the slurry level in the filter bottle and the falling speed. Stop vacuum filtration when the filtration rate is less than 10 drops per second. Before vacuum filtration, allow the dispersion to stand for 30 minutes. Take the top three-quarters of the dispersion as a stable binder for vacuum filtration. The vacuum filtration device consists of a filter bottle, filter membrane, sintered glass core, collection bottle, and an external vacuum pump. The vacuum pump generates negative pressure, creating a pressure difference across the filter membrane. This pressure difference drives the h-BN dispersion through the filter membrane, while the h-BN nanosheets are retained on the membrane. During retention, the h-BN nanosheets form conformal stacks, with each layer tightly packed and mutually adaptable to form the h-BN film. In this process, each layer precisely follows the surface morphology and contour of the layer below, thus forming a continuous and uniform multilayer structure. This stacking of structures reduces the gaps between layers, improving the compactness and stability of the h-BN film.

[0066] 6. Immerse the filter membrane with the attached h-BN film in a polar solvent for 3 seconds, then transfer it to a PET substrate. Allow the solvent to dry, then slowly peel off the filter paper. A dense, pure h-BN film is obtained. In this step, once the h-BN nanosheets conformally stack, they will not dissolve. Immersing the h-BN film along with the filter membrane in the polar solvent helps maintain its solvation state. After the h-BN film is transferred to the target substrate, as the solvent evaporates, adhesion switching at the interface begins, relatively weakening the adhesion at the h-BN / PTFE interface. After the solvent has completely evaporated, the adhesion in the entire system, from strongest to weakest, is: h-BN / target substrate > h-BN / h-BN > h-BN / PTFE. At this point, the PTFE filter membrane can be separated from the target substrate, while the h-BN film remains on the target substrate, completing the fabrication of the h-BN imaging plate. It is also important to note in this step that if dimethylformamide (DMF) is used as the polar solvent, since PTFE material is used as the filter membrane in this embodiment, and PTFE is difficult to wet in dimethylformamide (DMF), a small amount of isopropanol is needed to wet the PTFE filter membrane before filtration.

[0067] Please see Figure 5 The image shows a SEM surface feature map of the h-BN film prepared using the steps of this embodiment. As can be seen from the image, the surface of the h-BN film is mostly smooth. Please refer to [link to SEM image]. Figure 6The image shows a cross-sectional feature image of the h-BN film prepared using the steps of this embodiment, obtained by scanning electron microscopy. The image reveals that the thickness of the h-BN film is 13 ± 1 μm, indicating a very uniform thickness. Please refer to [link to relevant documentation]. Figure 7 The image shown is the XRD pattern of the h-BN thin film prepared in this embodiment, obtained by X-ray diffraction. The image reveals that the diffraction peak of the prepared h-BN thin film is located around 26.8°, which is a characteristic peak of its (002) crystal plane, and the interlayer spacing is approximately... Please see Figure 8 The image shows the Raman spectrum of the h-BN thin film prepared in this embodiment. The spectrum indicates that the h-BN thin film exhibits high density at approximately 1366 cm⁻¹. -1 A characteristic peak exists at this location, with no other peaks, consistent with the Raman spectrum of h-BN. From... Figure 9 , Figure 10 As can be seen from the photos, the prepared h-BN film has relatively complete edges.

[0068] Example 3

[0069] 1. Weigh 5g of h-BN powder and mix it evenly with 20g of urea granules, then pour the mixture into a ball mill. The particle size of h-BN is 1-2μm. In this step, the ball mill speed can be set to 600rpm and the working time can be set to 5 hours. During the ball milling process, open the lid every hour to check and observe the powder settling to the bottom and adhering to the inner wall of the ball mill jar, and stir evenly with a stirring rod.

[0070] 2. Add 500 mL of deionized water to the mixture of h-BN nanosheets and urea obtained after ball milling, filter out the zirconium beads, and stir the slurry evenly using a magnetic stirrer before placing it in a dialysis bag and letting it stand for four days. Specifically, the dialysis procedure in this step involves adding 10 mL of the initial slurry to each dialysis bag, dialyzing in deionized water for 3 days, changing the external deionized water every 24 hours, and using a dialysis bag with a molecular weight cutoff of 10000D.

[0071] In this embodiment, a dialysis bag with a molecular cutoff of 10,000D was selected to improve the dialysis efficiency of urea. After 3 days of dialysis, the urea clearance rate was greater than 99%, but the loss of h-BN nanosheets was greater than 5%.

[0072] 3. Weigh 150g of initial slurry, divide it into 3 equal portions and place them in a centrifuge. Set the centrifuge speed to 10,000 rpm and the centrifugation time to 1 hour.

[0073] 4. Add 50 mL of isopropanol (IPA) to the collected h-BN nanosheets and disperse them using an ultrasonic instrument. The frequency of the ultrasonic instrument is 25 MHz, the single dispersion time is set to 3-5 seconds, the interval time is 1 second, and the dispersion time is 30 minutes.

[0074] 5. Pour the dispersion into a vacuum filtration device and perform vacuum filtration to allow h-BN nanosheets to adhere to the filter membrane and form an h-BN film. Continuously observe the slurry level in the filter flask and the falling speed. Stop vacuum filtration when the filtration rate is less than 10 drops per second. Before vacuum filtration, allow the dispersion to stand for 30 minutes. Take the top three-quarters of the dispersion as a stable gel and perform vacuum filtration.

[0075] 6. Immerse the filter membrane with the attached h-BN film in a polar solvent for 3 seconds, then transfer it to a PET substrate. After the solvent dries, slowly peel off the filter paper. A dense, pure h-BN film can be obtained.

[0076] Example 4

[0077] 1. Weigh 5g of h-BN powder and mix it evenly with 20g of urea granules, then pour the mixture into a ball mill. The particle size of h-BN is 1-2μm. In this step, the ball mill speed can be set to 600rpm and the working time can be set to 5 hours. During the ball milling process, open the lid every hour to check and observe the powder settling to the bottom and adhering to the inner wall of the ball mill jar, and stir evenly with a stirring rod.

[0078] 2. Add 500 mL of deionized water to the mixture of h-BN nanosheets and urea obtained after ball milling, filter out the zirconium beads, and stir the slurry evenly using a magnetic stirrer before placing it in a dialysis bag and letting it stand for four days. Specifically, the dialysis procedure in this step involves adding 10 mL of the initial slurry to each dialysis bag, dialyzing in deionized water for 3 days, changing the external deionized water every 24 hours, and using a dialysis bag with a molecular weight cutoff of 10000D.

[0079] In this embodiment, a dialysis bag with a molecular cutoff of 6000D was selected. The dialysis efficiency of urea is lower than that of 8000D and 10000D dialysis bags, requiring 5 days of dialysis. The urea clearance rate is greater than 99%, and the loss of h-BN nanosheets is less than 5%.

[0080] 3. Weigh 150g of initial slurry, divide it into 3 equal portions and place them in a centrifuge. Set the centrifuge speed to 10,000 rpm and the centrifugation time to 1 hour.

[0081] 4. Add 50 mL of isopropanol (IPA) to the collected h-BN nanosheets and disperse them using an ultrasonic instrument. The frequency of the ultrasonic instrument is 25 MHz, the single dispersion time is set to 3-5 seconds, the interval time is 1 second, and the dispersion time is 30 minutes.

[0082] 5. Pour the dispersion into a vacuum filtration device and perform vacuum filtration to allow h-BN nanosheets to adhere to the filter membrane and form an h-BN film. Continuously observe the slurry level in the filter flask and the falling speed. Stop vacuum filtration when the filtration rate is less than 10 drops per second. Before vacuum filtration, allow the dispersion to stand for 30 minutes. Take the top three-quarters of the dispersion as a stable gel and perform vacuum filtration.

[0083] 6. Immerse the filter membrane with the attached h-BN film in a polar solvent for 3 seconds, then transfer it to a PET substrate. After the solvent dries, slowly peel off the filter paper. A dense, pure h-BN film can be obtained.

[0084] The above description merely illustrates preferred embodiments of the present invention and is quite specific and detailed; however, it should not be construed as limiting the scope of the invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the inventive concept, and these all fall within the scope of protection of the present invention. Therefore, the scope of protection of this invention should be determined by the appended claims.

Claims

1. A neutron imaging apparatus comprising a neutron source, a collimator, a neutron imaging plate, a first mirror, and an imaging apparatus, characterized by, Also include excitation source for emitting laser; the neutron imaging plate is h-BN imaging plate, including base and the h-BN film covered on the base, the h-BN film is by h-BN nanosheet conformal stack;The imaging device is CCD fluorescence imaging device;The thermal neutron of the neutron source emits is after passing through the collimator and is irradiated on the sample to be measured, part of thermal neutron irradiates on the h-BN imaging plate after penetrating the sample to be measured, is captured by the h-BN film 10 B capture, occur thermal neutron irradiation damage defect, and produce photoluminescence under the excitation of the laser source emits laser, and is reflected to the CCD fluorescence imaging device through the first mirror and completes the imaging of the sample to be measured.

2. The neutron imaging apparatus of claim 1, wherein, Further comprising a filter disposed between the first mirror and the CCD fluorescence imaging device, so that the photoluminescence of the h-BN is filtered by the filter after being reflected on the first mirror, and then enters the CCD fluorescence imaging device.

3. The neutron imaging apparatus of claim 1, wherein, The first mirror is a dichroic mirror for selectively reflecting the photoluminescence of the h-BN imaging plate.

4. The neutron imaging apparatus of claim 1, wherein, Further comprising a filter, and the first mirror is a dichroic mirror.

5. The neutron imaging apparatus of claim 1, wherein, Further comprising a second mirror disposed between the laser source and the h-BN imaging plate, and the laser emitted by the laser source can be reflected on the surface of the second mirror and then be emitted to the h-BN imaging plate.

6. A method for preparing a hexagonal boron nitride-based neutron imaging plate, comprising: S1: uniformly mixing h-BN powder and urea particles, pouring into a ball mill for ball milling to obtain a mixture of h-BN nanosheets and urea; S2: adding deionized water to the mixture of h-BN nanosheets and urea, placing in a dialysis bag after magnetic stirring, and standing to obtain an initial slurry; S3: removing water from the initial slurry in a centrifuge, and collecting h-BN nanosheets from the wall of the centrifuge tube; S4: placing the h-BN nanosheets in a polar solvent and dispersing them using an ultrasonic instrument to obtain a dispersion liquid; S5: placing the dispersion liquid in a vacuum filtration device to perform suction filtration on the dispersion liquid, so that the h-BN nanosheets are attached to the filter membrane and form an h-BN film; S6: transferring the h-BN film to a target substrate to obtain an h-BN imaging plate.

7. The hexagonal boron nitride-based neutron imaging plate production method according to claim 6, wherein In the S1 step, the mass ratio of the h-BN powder to the urea particles is 1:4, and the particle size of the h-BN powder is 1-2 μm.

8. The hexagonal boron nitride-based neutron imaging plate production method according to claim 6, wherein In the S2 step, the cut-off amount of the dialysis bag is 6000-10000 Da, and the standing time is 3-5 days.

9. The hexagonal boron nitride-based neutron imaging plate production method according to claim 6, wherein In the S4 step, the polar solvent is isopropyl alcohol or N-methyl pyrrolidone or dimethylformamide or dimethyl sulfoxide or deionized water.

10. The hexagonal boron nitride-based neutron imaging plate production method according to claim 6, wherein In the S5 step, the pore size of the filter membrane is 0.2 μm, and the material is PTFE.

11. The hexagonal boron nitride-based neutron imaging plate production method according to claim 6, wherein In the S6 step, before transferring the h-BN film to the target substrate, the filter membrane with the h-BN film needs to be soaked in a polar solvent for 3 s.

Images