Preparation method and application of carbon dot X-ray scintillator

Abstract

The invention discloses a preparation method of a carbon dot X-ray scintillator. The preparation method comprises the following steps: preparing a precursor mixture by taking tetraphenyl phosphorus iodide and urea as precursors; putting the precursor mixture into a reaction kettle, sealing, then putting the reaction kettle into a drying oven, heating to 180-210 DEG C, and reacting for 5-10 hours; adding the reacted precursor mixture into N, N-dimethylformamide for dissolving, and evaporating supernate on a heating table to dryness to obtain precursor powder; and dissolving the precursor powder in ethanol, and evaporating the supernate on a heating table to dryness to obtain the carbon dot X-ray scintillator. The preparation method is simple and low in cost. The photoyield of the carbon dot X-ray scintillator under X-ray excitation is greatly improved compared with that of a traditional organic scintillator. The carbon dot X-ray scintillator is formed into a thin film, so that the detection imaging function under X-rays can be realized.

Description

Technical Field

[0001] The present invention belongs to the field of radioluminescent carbon nanomaterials, relates to the technical field of radioluminescent carbon dot X-ray scintillators, and in particular to a preparation method and application of a carbon dot X-ray scintillator. Background Art

[0002] For indirect X-ray detection systems, scintillators are crucial for converting X-ray photons into visible light photons. When X-rays strike an object, different absorption rates of the X-rays in different parts of the object cause varying degrees of attenuation, resulting in different intensities of luminescence on the scintillator screen. This luminescence can be detected by a CCD detector. This unique imaging method makes X-ray detection important in medical examinations, industrial flaw detection, chip testing, and aerospace. Scintillator materials can also be used in specialized applications such as cosmic ray detection and particle detection. However, currently used inorganic scintillators such as YAG:Ce, NaI:Tl, CsI:Tl, and perovskites face drawbacks such as high preparation cost, complex manufacturing processes, poor stability, and toxicity. The development of new organic scintillators could expand their applications in X-ray detection.

[0003] Organic carbon dots have many advantages as a luminescent material, such as good environmental stability, low preparation cost, simple preparation process, and excellent optical properties such as large Stokes shift and tunable wavelength. These advantages make carbon dots promising to become a new type of high-performance scintillator material. However, since the elemental composition of carbon dots is mostly low atomic number (Z) such as C, H, O, N, the absorption coefficient of carbon dots to X-rays is extremely low. The low absorption coefficient leads to low radiation luminescence efficiency of carbon dots under X-rays, which seriously affects the imaging effect of carbon dot X-ray scintillators. Summary of the Invention

[0004] In order to solve the above technical problems, the present invention provides a preparation method and application of a carbon dot X-ray scintillator, which has a simple preparation method and low preparation cost.

[0005] The present invention is specifically achieved through the following technical solutions: A method for preparing a carbon dot X-ray scintillator comprises the following steps: (1) Using tetraphenylphosphonium iodide as precursor 1 and urea as precursor 2, grinding the precursor 1 and the precursor 2 in a mortar to obtain a precursor mixture, wherein the mass ratio of tetraphenylphosphonium iodide to urea is 1:5-7; (2) Place the precursor mixture in step (1) into a sealed reactor, then place the reactor in a drying oven, heat it to 180-210°C, and react for 5-10 hours; (3) adding N,N-dimethylformamide to dissolve the precursor mixture after the reaction in step (2), and evaporating the supernatant on a heating table to obtain a precursor powder; (4) The precursor powder in step (3) is dissolved in ethanol, and the supernatant is evaporated to dryness on a heating table to obtain a carbon dot X-ray scintillator.

[0006] The carbon dot X-ray scintillator is prepared into a carbon dot X-ray scintillator film, and the thickness of the carbon dot X-ray scintillator and the content of carbon dots are changed to make it meet the detection function under different X-ray energies.

[0007] Beneficial effects of the present invention: (1) The preparation method of the present invention is simple and low-cost. The light yield of the carbon dot X-ray scintillator under X-ray excitation is significantly improved compared to traditional organic scintillators. Compared with the light yield of the commercial organic scintillator anthracene (9500 photons / MeV), the light yield of the carbon dot X-ray scintillator is 312% (29640 photons / MeV), and the detection line is 500 nGy s -1 , which is far below the standard dose for medical testing; (2) Forming carbon dot X-ray scintillator into a thin film can achieve X-ray detection and imaging capabilities. The imaging resolution of the carbon dot X-ray scintillator film in the present invention reaches 18 microns, which can clearly detect the internal structure of a small fish about 3 cm in size and the internal vein structure of a leaf about 5 cm in size. BRIEF DESCRIPTION OF THE DRAWINGS

[0008] Figure 1 This is a transmission electron microscope image of the carbon dot X-ray scintillator prepared in Example 1; Figure 2 Spectra of the carbon dot X-ray scintillator prepared in Example 1 under ultraviolet light excitation (365 nm) and X-ray light excitation; Figure 3 This is a comparison spectrum of the light yield of the carbon dot X-ray scintillator prepared in Example 1 and the light yield of anthracene; Figure 4 The line-pair card imaging photograph and MTF diagram of the carbon dot X-ray scintillator film prepared in Example 1 under X-ray; Figure 5 The carbon dot X-ray scintillator film prepared in Example 1 is used to image a small fish under X-rays and the data analysis chart is shown; Figure 6 The carbon dot X-ray scintillator film prepared in Example 1 is used to image a leaf under X-rays and the data analysis chart is shown; Figure 7 Schematic diagram of the process for preparing thin films for carbon dot X-ray scintillators; Figure 8Films of three thicknesses and sizes prepared for the carbon dot X-ray scintillator of Example 1 DETAILED DESCRIPTION

[0009] Example 1 This embodiment provides a method for preparing a carbon dot X-ray scintillator, comprising the following steps: (1) Tetraphenylphosphonium iodide was selected as precursor 1 and urea was selected as precursor 2. Precursor 1 and precursor 2 were fully ground in a mortar at a mass ratio of 1:5.9 to fully mix the two precursors. (2) Place the sample thoroughly mixed in step (1) into a sealed reactor, place the reactor into a drying oven for heating treatment, set the temperature to 210 degrees, and heat the reaction for 8 hours; (3) Take out the sample from step (2) and place it in a beaker. Add 300 ml of NN-dimethylformamide (DMF) to fully dissolve the sample with DMF. Take out the fully dissolved supernatant and place it on a heating table for evaporation. (4) Take out the powder after evaporation in step (3), place the powder in a beaker and add 150 ml of anhydrous ethanol. Take out the supernatant that is fully dissolved in anhydrous ethanol and place it on a heating table. After evaporation, the carbon dot X-ray scintillator is obtained.

[0010] like Figure 1 As shown, the average particle size of the carbon dot X-ray scintillator is 6.19 nanometers and the lattice spacing is 0.21 nanometers. Figure 2 The luminescence center is shown to be 510 nm. Figure 3 The light yield of anthracene is 9500 photons / MeV, and the light yield of carbon dots is 29640 photons / MeV. Figure 4 The resolution is 17.8 lp / mm. Figure 7 Schematic diagram of the process of preparing carbon dot X-ray scintillator thin films, such as Figure 8 As shown, three films of thickness and size were prepared, with carbon dot contents of 0.5 g, 0.2 g, and 0.8 g from left to right, and polyvinyl alcohol contents of 10 ml.

[0011] Example 2 This embodiment provides a method for preparing a carbon dot X-ray scintillator, which is basically the same as the steps in Example 1, except that: in step (1), the mass ratio of precursor 1 to precursor 2 is 1:5; in step (2), the mixture in step (1) is reacted at a temperature of 210 degrees for 5 hours; in step (3), the sample in step (2) is added to 100 ml of DMF for treatment; in step (4), the sample evaporated in step (3) is placed in 50 ml of alcohol solution, and the supernatant is evaporated to dryness to obtain a carbon dot X-ray scintillator.

[0012] Example 3 This embodiment provides a method for preparing a carbon dot X-ray scintillator, which is basically the same as the steps of Example 1, except that: in step (1), the mass ratio of precursor 1 to precursor 2 is 1:5.5; in step (2), the mixture in step (1) is reacted at a temperature of 210 degrees for 7 hours; in step (3), the sample in step (2) is added to 200 ml of DMF for treatment; in step (4), the sample evaporated in step (3) is placed in 100 ml of alcohol solution, and the supernatant is evaporated to obtain a carbon dot X-ray scintillator.

[0013] Example 4 This embodiment provides a method for preparing a carbon dot X-ray scintillator, which is basically the same as the steps of Example 1, except that: in step (1), the mass ratio of precursor 1 to precursor 2 is 1:6.5; in step (2), the mixture in step (1) is reacted at a temperature of 210 degrees for 9 hours; in step (3), the sample in step (2) is added to 300 ml of DMF for treatment; in step (4), the sample evaporated in step (3) is placed in 200 ml of alcohol solution, and the supernatant is evaporated to obtain a carbon dot X-ray scintillator.

[0014] Example 5 This embodiment provides a method for preparing a carbon dot X-ray scintillator, which is basically the same as the steps of Example 1, except that: in step (1), the mass ratio of precursor 1 to precursor 2 is 1:7; in step (2), the mixture in step (1) is reacted at a temperature of 210 degrees for 10 hours; in step (3), the sample in step (2) is added to 500 ml of DMF for treatment; in step (4), the sample evaporated in step (3) is placed in 200 ml of alcohol solution, and the supernatant is evaporated to obtain a carbon dot X-ray scintillator.

Claims

1. A method for preparing a carbon dot X-ray scintillator, characterized in that: Here are the steps: (1) Using tetraphenylphosphonium iodide as precursor 1 and urea as precursor 2, grinding the precursor 1 and the precursor 2 in a mortar to obtain a precursor mixture, wherein the mass ratio of tetraphenylphosphonium iodide to urea is 1:5-7; (2) Place the precursor mixture in step (1) into a sealed reactor, then place the reactor in a drying oven, heat it to 180-210°C, and react for 5-10 hours; (3) adding N,N-dimethylformamide to dissolve the precursor mixture after the reaction in step (2), and evaporating the supernatant on a heating table to obtain a precursor powder; (4) The precursor powder in step (3) is dissolved in ethanol, and the supernatant is evaporated to dryness on a heating table to obtain a carbon dot X-ray scintillator.

2. The carbon dot X-ray scintillator prepared according to claim 1 is used in a carbon dot X-ray scintillator film.

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