Two-dimensional organic-inorganic hybrid lead-based halide scintillation single crystal and preparation method and application thereof

Abstract

The invention relates to a two-dimensional organic-inorganic hybrid lead-based halide scintillation single crystal as well as a preparation method and application thereof, and belongs to the technical field of crystal material imaging. Aiming at the problem that a scintillation single crystal prepared by a conventional preparation process is difficult to meet the requirement of high-frame-rate X-ray imaging application, the invention improves the content of Cl <-> in a crystal growth solution by changing a solution environment for crystal growth so as to adjust the luminescence and decay time of a crystal sample, so that the high-frame-rate X-ray imaging application is realized. The two-dimensional organic-inorganic hybrid lead-based halide scintillation single crystal (HAD) PbCl4 with adjustable luminescence and decay time and centimeter-level size is prepared, HAD represents a group diamine cation C5H9N32 +, and finally, high-frame-rate and ghosting-free dynamic X-ray imaging is promoted to be realized.

Description

Technical Field

[0001] The invention belongs to the technical field of crystal material imaging, and in particular relates to a two-dimensional organic-inorganic hybrid lead-based halide scintillation single crystal and a preparation method and application thereof. Background Art

[0002] X-ray imaging technology plays a vital role in many fields such as modern medicine, industrial testing, and scientific research. At the same time, the continuous advancement of science and technology has also increased the requirements for X-ray imaging. Traditional X-ray imaging technology is increasingly unable to cope with the detection of fast dynamic processes. For example: in the medical field, for the rapid movement of internal organs of the human body (such as heart beating, lung breathing, etc.), low frame rate imaging technology often finds it difficult to capture key instantaneous changes, which may lead to errors in diagnosis; in the industrial field, for the detection of high-speed mechanical equipment, fast production processes, etc., higher frame rate imaging technology is also required to detect potential problems in a timely manner.

[0003] The emergence of ultrafast scintillators (generally refers to scintillators with a decay time of less than 3ns) provides a new way to solve the above problems. Scintillators are key components in X-ray indirect detection imaging systems. They can convert invisible X-rays into visible light, which can be detected and imaged by complementary metal oxide semiconductor electronic devices or thin film transistor panels. In recent years, two-dimensional organic-inorganic hybrid lead-based halide scintillators have attracted widespread attention in the field of radiation detection due to their high effective atomic number, strong irradiation luminescence, nanosecond decay time, high stability and low cost. However, there are not many two-dimensional organic-inorganic hybrid lead-based halide scintillators used for X-ray imaging, especially those that use their fast decay time characteristics to achieve high frame rate dynamic X-ray imaging applications.

[0004] Scintillating single crystals can provide higher spatial resolution and clearer image quality. At the same time, large-sized (centimeter-level) scintillating single crystals are required to achieve high-resolution imaging applications. Although some previous patents and other documents have disclosed the traditional solution growth method of two-dimensional organic-inorganic hybrid lead-based materials, most of these materials prepared by most processes are polycrystalline or powder for solar cells or semiconductors, which are difficult to meet the needs of high-resolution imaging in X-ray imaging applications, and the effects of different solution growth environments on the luminescence properties of scintillating crystals have not been explored. Therefore, as a potential X-ray imaging material, further exploration of the preparation method and dynamic X-ray imaging applications of two-dimensional organic-inorganic hybrid lead-based halide scintillating single crystals is of great significance. Summary of the invention

[0005] In view of the above technical problems, the present invention aims to provide a two-dimensional organic-inorganic hybrid lead-based halide scintillating single crystal and its preparation method and application. By adjusting the crystal preparation method, that is, changing the solution environment of crystal growth, a two-dimensional organic-inorganic hybrid lead-based halide scintillating single crystal with adjustable luminescence and decay time and centimeter-level size is prepared, and static and dynamic X-ray imaging is realized. In particular, the fast decay time characteristics of the material under suitable preparation conditions are used to realize high frame rate and ghost-free dynamic X-ray imaging.

[0006] In a first aspect, the present invention provides a two-dimensional organic-inorganic hybrid lead-based halide scintillating single crystal, wherein the chemical formula of the two-dimensional organic-inorganic hybrid lead-based halide scintillating single crystal is (HAD)PbCl 4 ; Wherein, HAD represents a diamine cation C 5 H 9 N 3 2+ .

[0007] Preferably, the two-dimensional organic-inorganic hybrid lead-based halide scintillating single crystal emits blue light with a wavelength of 400-500 nm.

[0008] Preferably, the decay time of the two-dimensional organic-inorganic hybrid lead-based halide scintillating single crystal is ≤2 ns.

[0009] Preferably, the length dimension of the two-dimensional organic-inorganic hybrid lead-based halide scintillating single crystal is ≥1 cm.

[0010] In a second aspect, the present invention provides a method for preparing the above-mentioned two-dimensional organic-inorganic hybrid lead-based halide scintillating single crystal, the preparation method comprising the following steps: (1) According to the chemical formula of the two-dimensional organic-inorganic hybrid lead-based halide scintillating single crystal (HAD) PbCl 4 Weigh HAD·2HCl and PbCl in the stoichiometric ratio. 2 , then adding the two into an organic solvent-hydrochloric acid mixed solvent to dissolve and carry out solvent reaction to obtain a precursor solution; (2) The precursor solution is allowed to evaporate at a constant temperature to precipitate the two-dimensional organic-inorganic hybrid lead-based halide scintillating single crystal.

[0011] Preferably, in step (1), the organic solvent in the organic solvent-hydrochloric acid mixed solvent is dimethyl sulfoxide; and the concentration of hydrochloric acid used in the preparation of the organic solvent-hydrochloric acid mixed solvent is 10.8-12.1 mol / L.

[0012] Preferably, in step (1), the volume ratio of the organic solvent to the hydrochloric acid in the preparation of the organic solvent-hydrochloric acid mixed solvent is 5:0.3-0.5.

[0013] Preferably, in step (1), the group consisting of diamine hydrochloride HAD·2HCl, PbCl 2 The dosage ratio of the organic solvent-hydrochloric acid mixed solvent is 1 mol: 1 mol: 5.3-5.5 mL.

[0014] Preferably, in step (2), the temperature of the constant temperature static evaporation is ≥40°C and <70°C; and the time of the constant temperature static evaporation is 1-2 weeks.

[0015] In a third aspect, the present invention provides an application of the above-mentioned two-dimensional organic-inorganic hybrid lead-based scintillating single crystal in static and high frame rate dynamic X-ray imaging.

[0016] Beneficial Effects (1) (HAD)PbCl provided by the present invention 4 The single crystal scintillator is prepared by solution evaporation method, and further by adjusting the Cl content in the crystal growth solution - The content of can adjust the luminescence and decay time of the crystal sample; (2) The present invention is rich in Cl - (HAD)PbCl prepared under the crystallographic environment 4 Single crystals have higher X-ray irradiation luminescence intensity and faster decay time, which can achieve higher resolution X-ray imaging. They are especially useful for dynamic X-ray imaging, recording X-ray imaging of moving objects within a short time interval, and achieving dynamic X-ray imaging without ghosting and at a high frame rate. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 (HAD)PbCl prepared in Example 1 4 Schematic diagram of the lattice structure of a scintillating single crystal; Figure 2 The luminescence images of the single crystals prepared in Example 1, Comparative Example 1 and Comparative Example 2 under visible light and ultraviolet light excitation are shown; Figure 3 The simulated single crystal XRD and the actual XRD comparison diagram of the single crystals prepared in Example 1, Comparative Example 1 and Comparative Example 2 are shown; Figure 4 The fluorescence emission spectra of the single crystals prepared in Example 1, Comparative Example 1 and Comparative Example 2 are shown; Figure 5 The fluorescence decay time spectra of the single crystals prepared in Example 1, Comparative Example 1 and Comparative Example 2 are shown; Figure 6 The X-ray excitation emission spectra of the single crystals prepared in Example 1 and Comparative Example 1 are shown; Figure 7This is a static X-ray imaging image of the single crystal prepared in Comparative Example 1. Figure 7 (a) and Figure 7 (b) is the imaging resolution calculated using the standard line pair card and the MTF of the bright and dark areas in the image when it is 0.2. Figure 7 (c) is a demonstration of X-ray imaging of metal products; Figure 8 The centimeter-scale (HAD)PbCl prepared in Example 1 4 Static X-ray imaging of a scintillating single crystal. Figure 8 (a) and Figure 8 (b) is the imaging resolution calculated using the standard line pair card and the MTF of the bright and dark areas in the image when it is 0.2. Figure 8 (c) is a demonstration of X-ray imaging of metal products; Fig. 9 The centimeter-scale (HAD)PbCl prepared in Example 1 4 Dynamic X-ray imaging of scintillation single crystal at different rotation speeds; Fig.10 This is a photo of the luminescence of the single crystal prepared in Comparative Example 3 under ultraviolet light excitation; Fig.11 This is a photo of the luminescence of the single crystal prepared in Comparative Example 4 under ultraviolet light excitation; Fig.12 (HAD)PbCl prepared in Examples 2 and 3 4 Actual photo and fluorescence emission spectrum of scintillation single crystal under the excitation of fluorescent lamp and ultraviolet light. DETAILED DESCRIPTION

[0018] The present invention is further described below by way of embodiments. It should be understood that the following embodiments are only used to illustrate the present invention, but not to limit the present invention.

[0019] First, the present invention provides a two-dimensional organic-inorganic hybrid lead-based halide scintillating single crystal. The chemical formula of the two-dimensional organic-inorganic hybrid lead-based halide scintillating single crystal is (HAD)PbCl 4 , HAD represents the diamine cation C 5 H 9 N 3 2+ .

[0020] HAD is a multifunctional organic ion that can be used in inorganic layers [PbCl 4 ] and the bridging Cl - and terminal Cl -Combined to form multiple hydrogen bonds. At the same time, due to the large and asymmetric cation space effect of HAD, the crystal structure can have obvious mismatch arrangement. These factors together lead to (HAD)PbCl 4 The distorted lattice structure causes a large Stokes shift, which reduces the self-absorption effect and enhances the luminescence intensity, which in turn affects the (HAD)PbCl 4 Overall optical and decay time properties.

[0021] In some embodiments, the two-dimensional organic-inorganic hybrid lead-based halide scintillating single crystal can emit blue light with a wavelength of 400-500 nm.

[0022] In some embodiments, the decay time of the two-dimensional organic-inorganic hybrid lead-based halide scintillating single crystal is ≤2 ns.

[0023] In high-frame-rate dynamic X-ray imaging, the acquisition time of each frame is very short. If the decay time of the scintillator is too long, the light signal generated by the X-ray excitation of the previous frame has not yet completely decayed, and it will be superimposed on the light signal of the next frame, resulting in signal accumulation. This will reduce the contrast of the image, making it difficult to distinguish the object information at different time points, and reducing the time resolution and accuracy of the imaging.

[0024] In some embodiments, the length dimension of the two-dimensional organic-inorganic hybrid lead-halide-based scintillating single crystal is ≥1 cm.

[0025] If the length of the scintillator is too small, its ability to absorb X-rays and the amount of light signals generated will be reduced accordingly. This will reduce the light collection efficiency, resulting in insufficient light signal intensity received by the detector, affecting the imaging quality and signal-to-noise ratio. In low-dose X-ray imaging or detection of weak signals, small-sized scintillators may not meet the imaging requirements.

[0026] The following is an exemplary description of the preparation method of the above-mentioned two-dimensional organic-inorganic hybrid lead-based halide scintillating single crystal provided by the present invention. The preparation method may include the following steps: (1) According to the chemical formula of the two-dimensional organic-inorganic hybrid lead-based halide scintillating single crystal (HAD) PbCl 4 Weigh HAD·2HCl and PbCl in the stoichiometric ratio. 2 (molar ratio 1:1), then adding the two into an organic solvent-hydrochloric acid mixed solvent, mixing and dissolving in a sealed inert atmosphere and performing solvent reaction to obtain a clear, colorless precursor solution; (2) filtering the precursor solution, and evaporating the obtained filtrate at a constant temperature to precipitate the two-dimensional organic-inorganic hybrid lead-based halide scintillating single crystal.

[0027] In some embodiments, in step (1), the organic solvent in the organic solvent-hydrochloric acid mixed solvent may be dimethyl sulfoxide (DMSO).

[0028] In some embodiments, in step (1), the concentration of hydrochloric acid used in the preparation of the organic solvent-hydrochloric acid mixed solvent may be 10.8-12.1 mol / L.

[0029] In some embodiments, in step (1), the volume ratio of the organic solvent to the hydrochloric acid in the preparation of the organic solvent-hydrochloric acid mixed solvent can be 5:0.3-0.5.

[0030] It should be noted that (HAD)PbCl 4 The chloride ions in the single crystal growth precursor solution all come from HAD·2HCl organic ammonium salt and PbCl 2 The raw material dissociation creates a neutral environment, and the crystals grown in this solution environment mainly show white light emission and a relatively long decay time. However, the mixed solvent after adding hydrochloric acid provides additional chloride ions in addition to the raw material dissociation, creating a Cl-rich environment during the crystal growth process. - Environment, crystals grown in this environment tend to exhibit blue emission and ultrafast decay time.

[0031] At the same time, if the hydrochloric acid content in the organic solvent-hydrochloric acid mixed solvent is too low, the amount of hydrochloric acid in the crystal preparation process will be too small and volatile, and it will not be possible to create a Cl-rich - environment, thus failing to change the luminescence properties of the sample; if the hydrochloric acid content in the organic solvent-hydrochloric acid mixed solvent is too high, the crystal growth solution environment will be overly affected by the hydrochloric acid. The strong acidic environment caused by the excess hydrochloric acid solution will destroy the growth structure of the crystal, especially in the early stages of crystal growth. The tiny crystal nuclei are easily corroded and destroyed in the acid solution, making it difficult for them to further develop into large-sized crystals.

[0032] Create Cl-rich water with hydrochloric acid - The environment can effectively avoid the introduction of ionic impurities by other types of soluble chloride salts, thereby avoiding affecting the product composition or affecting the performance of the product due to the additional impurities introduced.

[0033] In some embodiments, in step (1), the group consisting of diamine hydrochloride HAD·2HCl, PbCl 2 The usage ratio of the organic solvent-hydrochloric acid mixed solvent can be 1 mol:1 mol:5.3-5.5 mL.

[0034] When the relative amount of the organic solvent-hydrochloric acid mixed solvent is too low, the raw materials cannot be completely dissolved; when the relative amount of the organic solvent-hydrochloric acid mixed solvent is too high, the crystal growth cycle will be too long, and the crystal growth solution environment will be too greatly affected by hydrochloric acid. The strong acidic environment caused by excessive hydrochloric acid solution may destroy the growth structure of the crystal. In the early stages of crystal growth, the tiny crystal nuclei are easily corroded and destroyed in the acid solution, making it difficult to further develop into large-sized crystals.

[0035] In some embodiments, in step (1), the inert atmosphere may be a nitrogen atmosphere.

[0036] In some embodiments, in step (1), the temperature of the solvent reaction can be room temperature-40°C, preferably 35-40°C, and the time of the solvent reaction can be 10-12 hours.

[0037] In some embodiments, in step (2), the pore size of the filter head used for the filtration may be 0.20-0.25 μm, preferably 0.22 μm. By filtering, it is possible to prevent the impurities in the precursor solution from affecting the formation of crystal nuclei in the subsequent crystallization process.

[0038] In some embodiments, in step (2), the temperature of the constant temperature static evaporation can be ≥40°C and <70°C, preferably 40°C, and the time of the constant temperature static evaporation can be 1-2 weeks, preferably 2 weeks.

[0039] By controlling the evaporation temperature of the solution, different crystal growth environments can be created, thereby controlling the size of the prepared crystals. In general, the boiling point of organic solvents is relatively high (the boiling point of DMSO is 189°C), so the mixed solvents for crystallization in a low-temperature environment are often difficult to evaporate to reach a saturated solution, resulting in a longer single crystal growth cycle. The present invention controls the temperature of the constant temperature static evaporation to ≥40°C and <70°C, so that the evaporation rate of the crystallization solvent is moderate, and the single crystal growth cycle is 1-2 weeks. Not only can a shorter single crystal growth cycle be ensured, but a moderate evaporation rate is conducive to the nucleation of the crystal and the gradual growth of the nucleus, and the prepared single crystal can reach a maximum of centimeters. However, although an excessively high evaporation temperature can accelerate the growth cycle of the crystal to a certain extent, the faster nucleation and growth rate are not conducive to the growth of the crystal, and the prepared single crystals are relatively small in size, mostly in the millimeter level; moreover, an excessively high evaporation temperature also increases the Cl in the solution. - The volatilization of Cl creates a crystal growth environment opposite to that after adding hydrochloric acid, that is, - environment.

[0040] Furthermore, compared with the conventional solution method for preparing only two-dimensional organic-inorganic hybrid lead-based materials, the (HAD)PbCl 4The single crystal preparation method creates a suitable Cl-rich - Environment: neutral, rich or lacking in Cl - Different crystallization environments can greatly affect the luminescence and scintillation properties of the material. Specifically: (1) (HAD)PbCl prepared under different crystal growth environments 4 The present invention shows different colors of luminescence characteristics. 4 The luminescence sources of the material were analyzed and it was found that the material has two luminescence sources. One luminescence source is the free exciton luminescence common in two-dimensional organic-inorganic hybrid lead-based materials, which usually emits blue light; the other luminescence source may be related to the defect bound exciton luminescence, that is, mainly related to Cl - Defects are related, usually emitting yellow light. In a neutral crystallization environment, the above two luminescences exist simultaneously, so the prepared (HAD)PbCl 4 Single crystals often show a mixture of two types of white light. - The environment reduces Cl - The generation of defects suppresses the yellow light emitted by defect-bound excitons, so the prepared (HAD)PbCl 4 The single crystal exhibits blue light emission from free excitons. - In the environment, the Cl in the crystal increases - The generation of defects greatly enhances the yellow light emitted by defect-bound excitons, so the prepared (HAD)PbCl 4 Single crystals often exhibit strong yellow light. (2) (HAD)PbCl prepared under different crystal growth environments 4 exhibit different decay times. As described in (1), (HAD)PbCl 4 The material has two sources of luminescence, which have different decay times. The blue-light-emitting free exciton luminescence usually has an extremely short decay time of a few nanoseconds, while the yellow-light-emitting defect-bound exciton luminescence usually has a long decay time of tens to hundreds of nanoseconds.

[0041] Therefore, under neutral conditions, (HAD)PbCl 4 The two luminescences of the single crystal mixed and showed a moderate decay time; Cl-rich - Under the environment, blue emitting (HAD)PbCl 4 Single crystals exhibit faster decay times; Cl-deficient - Under ambient conditions, yellow emitting (HAD) PbCl 4 Single crystals exhibit the longest decay times.

[0042] Faster decay time is conducive to dynamic X-ray imaging. Therefore, in order to achieve high frame rate dynamic X-ray imaging, it is preferred to use a suitable Cl-rich -In addition, X-ray imaging applications usually require large-sized (≥1 cm) single crystals. Therefore, in order to achieve high frame rate dynamic X-ray imaging, it is preferred to use the aforementioned suitable evaporation temperature to prepare centimeter-sized (HAD)PbCl 4 Single crystal.

[0043] In summary, the two-dimensional organic-inorganic hybrid lead-based scintillating single crystal finally prepared in the present invention can successfully achieve dynamic X-ray imaging images without ghosting and with high frame rate. - (HAD)PbCl prepared in solution 4 Single crystals exhibit higher irradiation luminescence response characteristics under X-ray radiation, achieving clear static and dynamic X-ray imaging of objects, especially in dynamic X-ray imaging, achieving a frame rate of 1000, which is significantly higher than the frame rate of dozens to two hundred of the currently common X-ray flat-panel detectors. It has important application prospects in X-ray imaging fields such as medical imaging and security inspection equipment.

[0044] The following further examples are given to illustrate the present invention in detail. It should also be understood that the following examples are only used to further illustrate the present invention and cannot be construed as limiting the scope of protection of the present invention. Some non-essential improvements and adjustments made by those skilled in the art based on the above content of the present invention all belong to the scope of protection of the present invention. The specific process parameters of the following examples are also only examples within a suitable range, that is, those skilled in the art can make selections within a suitable range through the description of this article, and are not limited to the specific values ​​​​exemplified below. If not specifically stated, the technical means used in the embodiments are conventional means well known to those skilled in the art.

[0045] Example 1 The two-dimensional organic-inorganic hybrid lead-based halide scintillating single crystal (rich Cl) provided in this embodiment - The preparation method of the solution environment comprises the following steps: (1) Mix HAD·2HCl organic ammonium salt (1 mol) and PbCl in a molar ratio of 1:1. 2 (1 mol) was dissolved in a mixed solvent consisting of 5 mL DMSO and 0.4 mL hydrochloric acid, sealed and stirred at room temperature for 12 hours in a nitrogen inert environment to allow it to completely dissolve and react fully to obtain a clear, colorless precursor solution; (2) The precursor solution obtained in step (1) is filtered through a 0.22 μm filter head, and the filtrate is placed at 40° C. for evaporation for 2 weeks to obtain the two-dimensional organic-inorganic hybrid lead-based halide scintillating single crystal.

[0046] Example 2 The two-dimensional organic-inorganic hybrid lead-based halide scintillating single crystal (rich Cl) provided in this embodiment -The preparation method of the solution environment) is as described in Example 1, with the main difference being: In step (1), the amount of hydrochloric acid used in the crystallization solvent is 0.3 mL.

[0047] Example 3 The two-dimensional organic-inorganic hybrid lead-based halide scintillating single crystal (rich Cl) provided in this embodiment - The preparation method of the solution environment) is as described in Example 1, with the main difference being: In step (1), the amount of hydrochloric acid used in the crystallization solvent is 0.5 mL.

[0048] Comparative Example 1 The preparation method of the single crystal (neutral solution environment) provided in this comparative example refers to Example 1, with the main differences being: In step (1), the crystallization solvent is only 5 mL of DMSO organic solvent.

[0049] Comparative Example 2 The single crystal (Cl-deficient) provided in this comparative example - The preparation method of the solution environment) is referred to Comparative Example 1, the main difference being that: In step (2), the filtrate is allowed to evaporate at 70°C for 1 week.

[0050] Comparative Example 3 The method for preparing the single crystal provided in this comparative example refers to that in Example 1, the main difference is that: In step (1), the amount of hydrochloric acid used in the crystallization solvent is 0.1 mL.

[0051] Comparative Example 4 The preparation method of the single crystal provided in this comparative example refers to Example 1, with the main differences being: In step (1), the amount of hydrochloric acid used in the crystallization solvent is 0.6 mL.

[0052] Figure 1 (HAD)PbCl prepared in Example 1 4 Schematic diagram of the lattice structure of the scintillating single crystal. As can be seen from the figure, (HAD)PbCl prepared in Example 1 4 Scintillating single crystals have a typical two-dimensional layered structure with alternating organic and inorganic layers. Figure 1 As can be seen in (a), the crystal structure consists of shared corners extending along the ac crystal planes PbCl 6 The metal halide octahedral inorganic layers are alternately composed of organic interlayer HAD cations located in the interlayer region of the inorganic framework. Figure 1As can be seen in (b), the stacking of the inorganic layers is irregular when viewed from the top-down direction. The mismatched arrangement of the inorganic layers is caused by the steric effect caused by the size and shape of the interlayer HAD ions and the hydrogen bonding interaction between the organic interlayer HAD cations and the inorganic layers.

[0053] Figure 2 The luminescence images of the single crystals prepared in Example 1, Comparative Example 1 and Comparative Example 2 under visible light and ultraviolet light excitation are shown in the figure. It can be seen from the figure that the scintillator single crystal prepared in Example 1 has good transparency under fluorescent lamp and shows blue light emission under ultraviolet lamp; the single crystal prepared in Comparative Example 1 has good transparency under fluorescent lamp but shows white light emission under ultraviolet lamp; the single crystal prepared in Comparative Example 2 has good transparency under fluorescent lamp but shows yellow light emission under ultraviolet lamp, and compared with the crystals prepared in Example 1 and Comparative Example 1, the (HAD)PbCl prepared under the growth conditions has good transparency under fluorescent lamp but shows yellow light emission under ultraviolet lamp. 4 Single crystals are relatively small, mostly at the millimeter level.

[0054] Figure 3 The simulated single crystal XRD and the actual XRD comparison diagram of the single crystal prepared in Example 1, Comparative Example 1, and Comparative Example 2. Among them, the actual XRD is obtained by grinding the single crystal into powder for testing, and the single crystal XRD spectrum is made according to the CIF card obtained by single crystal structure analysis. It can be seen from the figure that the XRD results of the single crystal prepared in Example 1, Comparative Example 1, and Comparative Example 2 are consistent with the XRD results of the single crystal simulation, the diffraction peak position does not move, and no extra impurity peaks appear, indicating that the synthesized (HAD)PbCl 4 They are all the same substance and have high purity and uniformity.

[0055] Figure 4 The fluorescence emission spectra of the single crystals prepared in Example 1, Comparative Example 1 and Comparative Example 2 are shown in FIG. As can be seen from the figure, (HAD)PbCl prepared in Example 1 4 The fluorescence emission spectrum of NH4Cl only shows an emission peak at 430 nm originating from free excitons. - (HAD)PbCl prepared in solution 4 The scintillating single crystal exhibits blue light emission under ultraviolet light excitation; (HAD)PbCl prepared in Comparative Example 1 4 The fluorescence emission spectrum of the (HAD)PbCl prepared in comparative example 1 under a neutral solution environment shows two emission peaks at 430 nm and 530 nm, wherein the blue light emission peak at 430 nm originates from the luminescence of free excitons, and the yellow light emission peak at 530 nm originates from the luminescence of defect-bound excitons. Since the blue light emission peak at 430 nm is higher than the yellow light emission peak at 530 nm, and both emission peaks can be observed, 4The single crystal exhibits white light emission under ultraviolet light excitation; (HAD)PbCl prepared in Comparative Example 2 4 The fluorescence emission spectrum of the sample also shows two emission peaks at 430 nm and 530 nm, but the yellow light emission peak intensity at 530 nm is higher than the blue light emission peak intensity at 430 nm. - (HAD)PbCl prepared in solution 4 The scintillating single crystals exhibit yellow light emission under UV light excitation.

[0056] Figure 5 The fluorescence decay time spectra of the single crystals prepared in Example 1, Comparative Example 1 and Comparative Example 2 are shown in FIG. - (HAD)PbCl prepared in solution 4 The scintillation single crystal has the fastest decay time, which is about 2 ns; the single crystal prepared in the neutral solution environment of the comparative example 1 has a moderate decay time, which is about 5 ns; the single crystal prepared in the Cl-deficient solution of the comparative example 2 has a moderate decay time, which is about 5 ns. - The single crystal prepared in solution environment has the longest decay time, which is about 14 ns.

[0057] Figure 6 The X-ray excitation emission spectra of the single crystals prepared in Example 1 and Comparative Example 1 are shown in the figure. - (HAD)PbCl prepared in solution 4 The scintillation single crystal has the highest irradiation luminescence intensity, and the single crystal prepared in comparative example 1 under a neutral solution environment has a lower irradiation luminescence intensity.

[0058] Figure 7 This is a static X-ray imaging image of the single crystal prepared in Comparative Example 1. Figure 7 (a) and Figure 7 (b) is the imaging resolution calculated using the standard line pair card and the MTF of the bright and dark areas in the image when it is 0.2. Figure 7 (c) is a demonstration of X-ray imaging of metal products. It can be seen from the figure that the imaging resolution of the single crystal prepared in Comparative Example 1 is about 17 lp / mm when the MTF of the bright and dark areas in the imaging image is calculated using the standard line pair card and the MTF=0.2, and relatively clear static imaging images can be obtained under different X-ray exposure times.

[0059] Figure 8 Centimeter-scale (about 2×1 cm in size) (HAD)PbCl was prepared for Example 1. 4 Static X-ray imaging of a scintillating single crystal. Figure 8 (a) and Figure 8(b) is the imaging resolution calculated using the standard line pair card and the MTF of the bright and dark areas in the image when it is 0.2. Figure 8 (c) is a demonstration of X-ray imaging of metal products. As can be seen from the figure, (HAD)PbCl prepared in Example 1 4 The imaging resolution of the scintillating single crystal calculated using the standard line pair card and the MTF of the bright and dark areas in the imaging image is about 18 lp / mm, and relatively clear static imaging images can be obtained at different X-ray exposure times.

[0060] Fig. 9 Centimeter-scale (about 2×1 cm in size) (HAD)PbCl was prepared for Example 1. 4 Dynamic X-ray imaging of scintillation single crystal at different rotation speeds. As can be seen from the figure, by adjusting the hertz of the chopper to change its rotation speed, the scintillation single crystal prepared in Example 1 shows clear dynamic X-ray imaging images at different rotation speeds and different exposure times, and the imaging receiving end can continuously shoot up to 1000 dynamic imaging pictures within 1 second without problems such as ghosting, achieving 1000 high frame rate dynamic X-ray imaging. However, due to the limitations of size and decay time, the crystal samples in the comparative example cannot perform clear dynamic imaging at a high frame rate.

[0061] Fig.10 This is a photo of the luminescence of the single crystal prepared in Comparative Example 3 under ultraviolet light excitation. It can be seen from the figure that the single crystal prepared in Comparative Example 3 is smaller in size than the crystal prepared in Example 1. More importantly, it may be because the amount of hydrochloric acid added is too small, and the effect of changing the growth environment to adjust the luminescence is not achieved, and it still shows the same white light emission as the single crystal grown under neutral conditions in Comparative Example 1.

[0062] Fig.11 This is a photo of the luminescence of the single crystal prepared in Comparative Example 4 under ultraviolet light excitation. As can be seen from the figure, the luminescence of the scintillator single crystal prepared in Comparative Example 4 is consistent with that of the crystal prepared in Example 1 under ultraviolet light, and both show strong blue light emission. However, the strong acidic environment caused by the excessive hydrochloric acid solution destroys the growth structure of the crystal. In the early stage of crystal growth, the tiny crystal nucleus is easily corroded and destroyed in the acid solution. Therefore, the crystal prepared under this growth condition has poor quality, serious crystal stacking, and is generally in the millimeter level, which is not suitable for X-ray imaging demonstration.

[0063] Fig.12 (HAD)PbCl prepared in Examples 2 and 3 4 The luminescence image and fluorescence emission spectrum of the scintillating single crystal under the excitation of fluorescent lamp and ultraviolet light. It can be seen from the figure that the (HAD)PbCl prepared in Examples 2 and 3 4The fluorescence emission spectrum of the scintillating single crystal is basically the same as that of Example 1, and only shows an emission peak at 430 nm originating from free excitons. - (HAD)PbCl prepared in solution 4 The scintillating single crystals exhibit blue light emission under UV light excitation.

[0064] Although the content of the present invention has been described in detail through the above preferred embodiments, it should be appreciated that the above description should not be considered as a limitation of the present invention. After reading the above content, it will be apparent to those skilled in the art that various modifications and substitutions of the present invention will occur. Therefore, the protection scope of the present invention should be limited by the appended claims.

Claims

1. A two-dimensional organic-inorganic hybrid lead-based halide scintillating single crystal, characterized in that: The chemical formula of the two-dimensional organic-inorganic hybrid lead-based halide scintillating single crystal is (HAD)PbCl4; wherein HAD represents a diamine cation C5H9N3 2+ .

2. The two-dimensional organic-inorganic hybrid lead-based halide scintillating single crystal according to claim 1, characterized in that: The two-dimensional organic-inorganic hybrid lead-based halide scintillating single crystal emits blue light with a wavelength of 400-500 nm.

3. The two-dimensional organic-inorganic hybrid lead-based halide scintillating single crystal according to claim 1, characterized in that: The decay time of the two-dimensional organic-inorganic hybrid lead-based halide scintillating single crystal is ≤2 ns.

4. The two-dimensional organic-inorganic hybrid lead-based halide scintillating single crystal according to claim 1, characterized in that: The length dimension of the two-dimensional organic-inorganic hybrid lead-based halide scintillating single crystal is ≥1 cm.

5. A method for preparing a two-dimensional organic-inorganic hybrid lead-based halide scintillating single crystal according to any one of claims 1 to 4, characterized in that: The preparation method comprises the following steps: (1) weighing histidine hydrochloride HAD·2HCl and PbCl2 according to the stoichiometric ratio in the chemical formula (HAD)PbCl4 of the two-dimensional organic-inorganic hybrid lead-based halide scintillating single crystal according to any one of claims 1 to 4, and then adding the two to an organic solvent-hydrochloric acid mixed solvent to dissolve and perform solvent reaction to obtain a precursor solution; (2) The precursor solution is allowed to evaporate at a constant temperature to precipitate the two-dimensional organic-inorganic hybrid lead-based halide scintillating single crystal.

6. The preparation method according to claim 5, characterized in that In step (1), the organic solvent in the organic solvent-hydrochloric acid mixed solvent is dimethyl sulfoxide; the concentration of hydrochloric acid used in the preparation of the organic solvent-hydrochloric acid mixed solvent is 10.8-12.1 mol / L.

7. The preparation method according to claim 6, characterized in that In step (1), the volume ratio of the organic solvent to the hydrochloric acid in the preparation of the organic solvent-hydrochloric acid mixed solvent is 5:0.3-0.

5.

8. The preparation method according to claim 5, characterized in that In step (1), the ratio of the diamine hydrochloride HAD·2HCl, PbCl2 and the organic solvent-hydrochloric acid mixed solvent is 1 mol: 1 mol: 5.3-5.5 mL.

9. The preparation method according to claim 5, characterized in that: In step (2), the temperature of the constant temperature static evaporation is ≥40°C and <70°C; and the time of the constant temperature static evaporation is 1-2 weeks.

10. Use of the two-dimensional organic-inorganic hybrid lead-based scintillating single crystal according to any one of claims 1 to 4 in static and high frame rate dynamic X-ray imaging.

Images