Rare earth complex organic doping technology applied to X-ray high-precision detection

Abstract

The invention discloses a rare earth complex organic doping technology applied to X-ray high-precision detection. The rare earth complex Tb-1 crystal is synthesized by taking Tb (NO3) 3.5 H2O, Ga (NO3) 3 * x (H2O), salicylhydroxamic acid, sodium benzoate and pyridine as raw materials. On the basis, an organic dopant pyromellitic acid (PMA) is introduced, a crystal structure is regulated and controlled, and the Tb-1-PMA is named as Tb-1-PMA. The Tb-1-PMA generates green fluorescence visible to naked eyes under the irradiation of X rays. Through regulation and control of the organic dopant, compared with Tb-1, the Tb-1-PMA has the advantages that the fluorescence quantum yield is increased from 36.8% to 45.3%, the light yield is increased from 12000 photons MeV <-1 > to 20000 photons MeV <-1 >, and the detection limit of the Tb-1-PMA for X-ray dose detection reaches 0.044 mu Gy s <-1 > which is lower than the medical X-ray treatment dose rate by 123 times. A new thought is provided for improving the performance of the rare earth complex scintillation crystal, and the rare earth complex scintillation crystal has good development and application prospects in the field of low-dose X-ray detection.

Description

Technical Field

[0001] The invention mainly relates to the design of rare earth complex scintillation crystal structure and the application field of X-ray high-precision detection, in particular to an organic doping technology for improving the radiation luminescence performance of scintillation crystal. Background Art

[0002] High-energy photons such as X-rays and gamma rays can penetrate most objects and are absorbed to varying degrees when passing through them. Therefore, they are widely used in darkroom detection, such as medical imaging, industrial flaw detection, and security inspection. However, humans cannot directly observe high-energy photons. Therefore, scintillation materials are needed to convert high-energy photons into visible light.

[0003] However, the preparation cost of traditional scintillating materials such as CsI:Tl, LSO:Ce, and BGO is high and the process is complicated, which makes the price of medical imaging equipment as high as millions of dollars. Therefore, the development of scintillating materials with better performance has important theoretical and application value.

[0004] Rare earth elements have the characteristics of long luminescence lifetime, narrow half-peak width, and no influence from molecular environment, which have great advantages in sensing detection. The use of organic ligand coordination is an effective technical means to improve the luminescence efficiency of rare earth ions. Then, rare earth ions have a high coordination number of 8 to 12, and they have a variety of coordination modes with organic ligands, and most of the coordination modes have low radiation luminescence efficiency. Therefore, it is of great significance to improve the performance of rare earth complex scintillation crystals by doping and regulating the microstructure, so as to achieve more sensitive and accurate detection of low-dose X-rays. Summary of the invention

[0005] One object of the present invention is to improve the performance of rare earth complex scintillation crystals by using organic doping technology. 3+ As a launch center, Ga 3+ As coordination auxiliary ions, salicylic acid, sodium benzoate and pyridine are used as organic ligands, and a certain concentration of pyromellitic acid (PMA) is added as an organic dopant to adjust the microstructure of the rare earth complex scintillation crystal. After the conditions are optimized, the light yield of the rare earth complex scintillation crystal is about 20,000 photons MeV -1 , exhibiting an excellent linear response under X-ray excitation with a detection limit of approximately 0.044 μGy s -1 , which is about 123 times lower than the commonly used X-ray treatment dose.

[0006] Another object of the present invention is to provide a method for preparing the rare earth complex scintillation crystal material, the method comprising the following steps:

[0007] 1) Mix a rare earth ion source Tb(NO3)3·5H2O, an auxiliary ion source Ga(NO3)3·x(H2O), an organic ligand salicylic acid, sodium benzoate and pyridine in a ratio of 1:4:4:12:97, add 4000 parts of methanol as a solvent, stir well to dissolve the above raw materials, and filter to obtain a clear solution.

[0008] 2) PMA is added as an organic dopant, and the amount of PMA added is 0.25% to 1.5% of salicylic hydroxamic acid.

[0009] 3) The mixed solution is placed in a dry and ventilated place and allowed to stand for several days to precipitate pale yellow crystals, which are the final product. The product produces bright green fluorescence under X-ray irradiation.

[0010] The invention has the advantages of high radiation luminescence efficiency, low material cost, low preparation environment requirement (room temperature is sufficient), and is non-toxic and environmentally friendly. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Figure 1 : X-ray diffraction spectra of terbium organic complex scintillating crystals in Examples 1 and 2 (doped with 1% PMA).

[0012] Figure 2 : Scanning electron microscopy images of terbium organic complex scintillating crystals in Examples 1 and 2 (doped with 1% PMA).

[0013] Figure 3 : Element distribution (Tb and Ga) and energy spectrum of terbium organic complex scintillating crystal in Example 2 (doped with 1% PMA).

[0014] Figure 4 : X-ray excitation spectra of the terbium organic complex scintillation crystal in Example 1 and the PMA-doped terbium organic complex scintillation crystal in Example 2, wherein commercial CSI (Tl) is used as a control.

[0015] Figure 5 : Linear relationship diagram between X-ray excited luminescence intensity and X-ray dose rate of the terbium organic complex scintillation crystal doped with 1% PMA in Example 2.

[0016] Figure 6 : Spectral diagram of the terbium organic complex scintillation crystal doped with PMA in different proportions under X-ray excitation in Example 2 and dot-line diagram of the luminescence intensity of the terbium organic complex scintillation crystal doped with PMA in different proportions at 545nm.

[0017] Figure 7 : Quantum efficiency spectra of the terbium organic complex scintillation crystal in Example 1 and the terbium organic complex scintillation crystal doped with 1% PMA in Example 2. DETAILED DESCRIPTION

[0018] The present invention is further described in detail below in conjunction with specific implementation modes, but the protection scope of the present invention is not limited to the described contents.

[0019] Example 1: Preparation of rare earth Tb organic complex scintillation crystals:

[0020] The rare earth ion source Tb(NO3)3·5H2O, the auxiliary ion source Ga(NO3)3·x(H2O), the organic ligand salicylic acid, sodium benzoate and pyridine were mixed in the proportion of 1:4:4:12:97, 4000 parts of methanol were added as solvent, the above raw materials were fully stirred to dissolve, and a clear solution was obtained by filtering. The above mixed solution was placed in a dry and ventilated place, and after standing for several days, pale yellow crystals were precipitated, which was the final product, named Tb-1.

[0021] Example 2: Terbium complex scintillation crystals doped with PMA in different proportions.

[0022] The rare earth ion source Tb(NO3)3·5H2O, the auxiliary ion source Ga(NO3)3·x(H2O), the organic ligand salicylic acid, sodium benzoate and pyridine are mixed in the proportion of 1:4:4:12:97, 4000 parts of methanol are added as a solvent, the above raw materials are fully stirred to dissolve, and a clear solution is obtained by filtering. PMA is added as an organic dopant, and the amount of PMA added is 0.25% to 1.5% of salicylic acid. The above mixed solution is placed in a dry and ventilated place, and light yellow crystals are precipitated after standing for several days, which is the final product, named Tb-1-PMA.

[0023] Figure 1 The X-ray powder diffraction patterns of samples 1 and 2 of this embodiment show that the X-ray powder diffraction peaks of the prepared samples are consistent with those in the literature (Zi Chen, et al. Triplet Exciton Enhanced Radioluminescence of Ga 3+ / Tb 3+ The results show that the material preparation is consistent with the standard sample in Metallacrown Scintillators for X-Ray Detection. Adv. Optical Mater. 2021, 2102074., indicating that the material preparation is successful.

[0024] Figure 2 The scanning electron microscope images of the samples of Examples 1 and 2 (doped with 1% PMA) show that the crystals have a layered structure before and after doping. The crystal plane of Tb-1-PMA crystal is relatively more stable, while some crystal planes of Tb-1 are bent.

[0025] Figure 3This is the element distribution and energy spectrum diagram of the crystal obtained in Example 2 (doped with 1% PMA). It can be seen from the figure that the element composition of the crystal is C, O, Tb and Ga, and Tb and Ga are evenly distributed in the crystal.

[0026] Figure 4 The spectra of the samples of this embodiment and embodiments 1 and 2 (doped with 1% PMA) under X-ray excitation are shown, and commercial CSI (Tl) is used for comparison. It can be seen from the figure that the Tb-1-PMA has stronger radiant luminescence than Tb-1, and the luminous intensity at the 545nm emission peak is 68% higher than that of the sample before doping, and 150% higher than the peak of CSI (Tl).

[0027] Figure 5 The linear relationship between the X-ray luminescence intensity and the X-ray dose rate of Tb-1-PMA (1%) in Example 2 is shown in the figure. -1 Under X-ray excitation, Tb-1-PMA has a good linear response to X-rays, and the calculated detection limit is 0.044 μGy s -1 , which is about 123 times lower than the commonly used X-ray treatment dose.

[0028] Figure 6 The spectrum diagram of Tb-1-PMA doped with different proportions of PMA under X-ray excitation and the dotted line diagram of the luminescence intensity at 545nm in Example 2. It can be seen from the figure that when the doping ratio of the dopant PMA is 1%, the radiated luminescence intensity is the highest.

[0029] Figure 7 The quantum efficiency spectra of Tb-1 and Tb-1-PMA (1%) in Examples 1 and 2 are obtained through area calculation. After PMA doping, the quantum efficiency of the Tb organic complex scintillation crystal is increased from 36.8% to 45.3%.

[0030] The specific embodiments of the present invention are described in detail above, but the present invention is not limited to the above embodiments. Various changes can be made within the knowledge scope of ordinary technicians in this field without departing from the purpose of the present invention.

Claims

1. A rare earth complex organic doping technology is applied to high-precision X-ray detection. It is characterized by: After organic doping, the fluorescence quantum yield of the scintillating crystal increased from 36.8% to 45.3%, and the light output increased from 12000photons MeV -1 Increased to 20,000 photons MeV -1 The detection limit of X-ray detection is 0.044 μGy s -1 , the preparation method comprises the following steps: 1) Mix a rare earth ion source Tb(NO3)3·5H2O, an auxiliary ion source Ga(NO3)3·x(H2O), an organic ligand salicylic acid, sodium benzoate and pyridine in a ratio of 1:4:4:12:97, add 4000 parts of methanol as a solvent, stir well to dissolve the above raw materials, and filter to obtain a clear solution. 2) Add pyromellitic acid as an organic dopant, wherein the amount of pyromellitic acid added is 0.25% to 1.5% of salicylic hydroxamic acid. 3) The mixed solution is placed in a dry and ventilated place and allowed to stand for several days to precipitate pale yellow crystals, which are the final product. The product produces bright green fluorescence under X-ray or ultraviolet light.

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