Near-infrared scintillation crystal and preparation method thereof

Abstract

The invention discloses a near-infrared scintillation crystal and a preparation method thereof. The chemical formula of the scintillation crystal is Cs3Ce1-yX6: ySb, wherein X is selected from at least one of Cl and Br; the value range of y is more than or equal to 0.001 and less than or equal to 0.06. The scintillation crystal is prepared by adopting a Bridgman-Stockbarger method, can emit broadband near-infrared light with the wavelength of 800-1000nm under the excitation of high-energy rays or high-energy particles, and is matched with the detection wavelength of an APD (Avalanche Photo Diode) and an SiPM (Silicon Particulate Matrix) detector with high quantum efficiency.

Description

Technical Field

[0001] The invention belongs to the technical field of scintillation materials, and in particular relates to a near-infrared scintillation crystal and a preparation method thereof. Background Art

[0002] Scintillator crystal is a material that absorbs high-energy rays or particles such as X-rays and gamma rays and then emits low-energy photons with wavelengths ranging from ultraviolet to near-infrared. Scintillation detectors composed of scintillator crystals coupled with photosensitive elements are widely used in important fields such as nuclear medical imaging, homeland security, and high-energy physics. Scintillation detectors are mainly composed of scintillators and photodetectors. In order to achieve high energy resolution, this requires not only that the scintillator itself has high scintillation performance, but also that the scintillator and photodetector must have good wavelength matching and high quantum efficiency.

[0003] The emission wavelengths of the scintillation crystals developed so far are in the ultraviolet or blue spectrum, and they have a good match with the sensitive detection wavelength of the photomultiplier tube (PMT). However, the quantum efficiency (QE) of the PMT is low, generally only about 20%. In contrast, the newly developed avalanche photodiode (APD) and silicon photomultiplier tube (SiPM) have much higher quantum efficiencies than PMTs. The QE of SiPM sensitive to long-wave near-infrared light can reach 40%, and the QE of APD silicon photodetectors at 700-900nm can reach 80%-90%, and can even exceed 90% after optimization. Theoretically, when the APD detection efficiency reaches 98%, the crystal light yield only needs to reach more than 62000ph / MeV, and the energy resolution of 662keV gamma rays can reach 2%. However, there are very few scintillation crystals that can be coupled with high-quantum-efficiency APDs or SiPMs to emit red or near-infrared light.

[0004] Eu 2+ -Sm 2+ The co-doped red-near infrared halide scintillator crystal has a wavelength of 700-900 nm, which is a good wavelength match with high quantum efficiency APD and SiPM detectors. 2+ -Sm 2+ There is a problem of low energy transfer efficiency between them. In addition, the ns with significant Stokes shift 2 Metal ions are the first choice for near-infrared scintillation luminescence. Sb 3+ Due to its non-toxicity and extreme chemical stability, 2 However, the existing Sb 3+ It is difficult to achieve broadband near-infrared light emission by doping luminescent materials. Summary of the invention

[0005] One of the purposes of the present invention is to provide a near-infrared scintillation crystal, which can realize near-infrared luminescence and has wide application in the field of radiation detection.

[0006] The second object of the present invention is to provide a method for preparing the above-mentioned near-infrared scintillation crystal, which is easy to realize industrial production.

[0007] In order to achieve the above object, the technical solution adopted by the present invention is as follows:

[0008] In a first aspect, the present invention provides a near-infrared scintillation crystal, wherein the chemical formula of the scintillation crystal is:

[0009] CxC 1-y X6:ySb,

[0010] Wherein X is selected from at least one of Cl and Br; and the value range of y is 0.001≤y≤0.06.

[0011] The scintillation crystal can emit broadband near-infrared light between 800 and 1000 nm under the excitation of high-energy rays or high-energy particles.

[0012] In a second aspect, the present invention also provides a method for preparing the above-mentioned near-infrared scintillation crystal, which is prepared by a crucible descent method and specifically comprises the following steps:

[0013] (1) According to the chemical formula Cs3Ce 1-y The stoichiometric ratio of each element in X6:ySb is that CsX powder, CeX3 powder, and SbX3 powder are prepared in a glove box at a molar ratio of 3:1-y:y, and are fully mixed to form a raw material powder, wherein X is selected from at least one of Cl and Br; 0.01≤y≤0.06;

[0014] (2) The raw material powder is placed in a quartz crucible with a capillary structure under an inert atmosphere and heated for 10 -3 ~10 -7 Baking the material at a vacuum degree of Pa and 150-250°C for 12-60 hours, and sealing the quartz crucible by welding after cooling down;

[0015] (3) placing the sealed quartz crucible in a crucible descending furnace, and raising the temperature of the crucible descending furnace to 50 to 150° C. above the melting point of the raw material to completely melt the raw material powder;

[0016] (4) adjusting the temperature of the bottom of the quartz crucible to the melting point of the crystal, controlling the temperature gradient of the growth interface of the crucible descending furnace to be 5 to 40°C / cm, and then descending the quartz crucible in the furnace body at a descending speed of 0.01 to 10 mm / h, and the crystal nucleates and grows from the capillary bottom of the crucible until the melt is completely solidified;

[0017] (5) After the growth is completed, the temperature is slowly lowered to room temperature at a cooling rate of 0.1 to 40°C / h, and the prepared crystal is taken out from the quartz crucible in a dry environment.

[0018] Preferably, in step (4), the descending speed of the quartz crucible is 0.4 to 1 mm / h.

[0019] Preferably, in step (1), the purity of the raw material powder is ≥ 99.9wt%.

[0020] Preferably, in step (2), the inert atmosphere is argon or nitrogen.

[0021] Compared with the prior art, the present invention has the following beneficial effects:

[0022] 1. The present invention uses Sb 3+ As a scintillation luminescence activator, Sb 3+ With Ce 3+ The radius is not much different, so it can be easily doped into Cs3Ce 1-y The emission wavelength of the prepared near-infrared scintillation crystal under X-ray irradiation is 800-1000nm, with a peak wavelength at 911nm, which can match the detection wavelength of high quantum efficiency APD and SiPM detectors.

[0023] 2. The near-infrared scintillation crystal prepared by the present invention has low hygroscopicity and does not contain natural radioactive elements, and does not require packaging and protection during actual use. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 The Cs3Ce prepared in Example 1 0.94 Powder X-ray diffraction of Cl6:6%Sb scintillating crystal compared with the Cs3CeCl6 standard PDF card.

[0025] Figure 2 The Cs3Ce prepared in Example 1 0.94 X-ray excitation emission spectrum of Cl6:6%Sb scintillation crystal.

[0026] Figure 3 The Cs3Ce prepared in Example 1 0.94 Comparison of the hygroscopicity curves of Cl6:6%Sb, NaI and LaBr3. DETAILED DESCRIPTION

[0027] The present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0028] The present invention further shows the following examples to better illustrate the present invention. It should be understood that the following examples are only used to further illustrate the present invention and cannot be understood as limiting the scope of protection of the present invention. Some homogeneous adjustments and optimizations made by those skilled in the art based on the above content of the present invention belong to the scope of protection of the present invention.

[0029] The experimental methods in the following examples without specifying specific conditions are usually based on conventional conditions.

[0030] The raw material powders used in the following examples are all commercially available products.

[0031] Example 1: Cs3Ce 0.94 Preparation of Cl6:6%Sb scintillation crystal

[0032] (1) In a glove box, CsCl, CeCl3 and SbCl3 powders with a purity of 99.99% were weighed according to the stoichiometric ratio, with the weights being 6.730 g, 3.087 g and 0.182 g respectively, and were mixed uniformly as raw materials and added into a quartz crucible;

[0033] (2) In a glove box filled with argon, the raw material powder was placed in a quartz crucible with a capillary structure and heated for 10 -5 The material was dried at 200°C for 20 hours under a vacuum degree of Pa, and after cooling, the quartz crucible was sealed with a hydrogen-oxygen welding torch;

[0034] (3) placing the sealed quartz crucible in a crucible descending furnace, and heating the crucible descending furnace to 900° C. until the mixed powder raw materials are completely melted;

[0035] (4) adjusting the temperature of the bottom of the crucible to the melting point of the crystal, controlling the growth temperature gradient of the crucible descending furnace to 20°C / cm, and then descending the quartz crucible in the furnace body at a descending speed of 0.4 mm / h, and the crystal nucleates and grows from the capillary bottom of the crucible until the melt is completely solidified;

[0036] (5) After the growth is completed, the temperature is slowly lowered to room temperature at a cooling rate of 15°C / h, and the prepared crystal is taken out from the quartz crucible in a dry environment.

[0037] Figure 1 The Cs3Ce prepared in this example 0.94 The comparison of the powder X-ray diffraction of Cl6:6%Sb scintillating crystal and the standard PDF card of Cs3CeCl6; Figure 1 It can be seen that the scintillation crystal is a Cs3CeCl6 crystal.

[0038] Figure 2 The Cs3Ce prepared in this example 0.94 X-ray excitation emission spectrum of Cl6:6%Sb scintillation crystal; Figure 2 It can be seen that the emission wavelength of the scintillation crystal is 800-1000 nm, with a peak wavelength at 911 nm, which matches the detection wavelength of high quantum efficiency APD and SiPM detectors.

[0039] Figure 3 The Cs3Ce prepared in this example 0.94 Comparison of the hygroscopicity curves of Cl6:6%Sb, NaI and LaBr3; Figure 3 It can be seen that the hygroscopicity of the scintillating crystal is significantly lower than that of NaI and LaBr3.

[0040] Example 2: Cs3Ce 0.999 Preparation of Cl6:0.1%Sb scintillation crystal

[0041] (1) In a glove box, CsCl, CeCl3 and SbCl3 powders with a purity of 99.99% were weighed according to the stoichiometric ratio, with the weights being 6.721 g, 3.276 g and 0.003 g respectively, and were mixed uniformly as raw materials and added into a quartz crucible;

[0042] (2) In a glove box filled with argon, the raw material powder was placed in a quartz crucible with a capillary structure and heated for 10 -5 The material was dried at 200°C for 20 hours under a vacuum degree of Pa, and after cooling, the quartz crucible was sealed with a hydrogen-oxygen welding torch;

[0043] (3) placing the sealed quartz crucible in a crucible descending furnace, and heating the crucible descending furnace to 900° C. until the mixed powder raw materials are completely melted;

[0044] (4) adjusting the temperature of the bottom of the crucible to the melting point of the crystal, controlling the growth temperature gradient of the crucible descending furnace to 10°C / cm, and then descending the quartz crucible in the furnace body at a descending speed of 1 mm / h, and the crystal nucleates and grows from the capillary bottom of the crucible until the melt is completely solidified;

[0045] (5) After the growth is completed, the temperature is slowly lowered to room temperature at a cooling rate of 3°C / h, and the prepared crystal is taken out from the quartz crucible in a dry environment.

[0046] The Cs3Ce prepared in this example 0.999 The powder X-ray diffraction pattern and X-ray excitation emission spectrum of the Cl6:0.1%Sb scintillation crystal are similar to those of Example 1.

[0047] Example 3: Cs3Ce 0.94 Preparation of Br6:6%Sb scintillation crystal

[0048] (1) In a glove box, CsBr, CeBr3 and SbBr3 powders with a purity of 99.99% were weighed according to the stoichiometric ratio, with the weights being 6.277 g, 3.510 g and 0.213 g, respectively, and mixed uniformly as raw materials into a quartz crucible;

[0049] (2) In a glove box filled with argon, the raw material powder was placed in a quartz crucible with a capillary structure and heated for 10 -5 The material was dried at 200°C for 20 hours under a vacuum degree of Pa, and after cooling, the quartz crucible was sealed with a hydrogen-oxygen welding torch;

[0050] (3) placing the sealed quartz crucible in a crucible descending furnace, and heating the crucible descending furnace to 700° C. until the mixed powder raw materials are completely melted;

[0051] (4) adjusting the temperature of the bottom of the crucible to the melting point of the crystal, controlling the growth temperature gradient of the crucible descending furnace to 20°C / cm, and then descending the quartz crucible in the furnace body at a descending speed of 0.4 mm / h, and the crystal nucleates and grows from the capillary bottom of the crucible until the melt is completely solidified;

[0052] (5) After the growth is completed, the temperature is slowly lowered to room temperature at a cooling rate of 20°C / h, and the prepared crystal is taken out from the quartz crucible in a dry environment.

[0053] The Cs3Ce prepared in this example 0.94 The powder X-ray diffraction pattern and X-ray excitation emission spectrum of the Br6:6%Sb scintillation crystal are similar to those of Example 1.

[0054] Example 4: Cs3Ce 0.999 Preparation of Br6:0.1%Sb scintillation crystal

[0055] (1) In a glove box, CsBr, CeBr3 and SbBr3 powders with a purity of 99.99% were weighed according to the stoichiometric ratio, with the weights being 6.270 g, 3.727 g and 0.003 g respectively, and were mixed uniformly as raw materials and added into a quartz crucible;

[0056] (2) In a glove box filled with argon, the raw material powder was placed in a quartz crucible with a capillary structure and heated for 10 -5 The material was dried at 200°C for 20 hours under a vacuum degree of Pa, and after cooling, the quartz crucible was sealed with a hydrogen-oxygen welding torch;

[0057] (3) placing the sealed quartz crucible in a crucible descending furnace, and heating the crucible descending furnace to 700° C. until the mixed powder raw materials are completely melted;

[0058] (4) adjusting the temperature of the bottom of the crucible to the melting point of the crystal, controlling the growth temperature gradient of the crucible descending furnace to 5°C / cm, and then descending the quartz crucible in the furnace body at a descending speed of 1 mm / h, and the crystal nucleates and grows from the capillary bottom of the crucible until the melt is completely solidified;

[0059] (5) After the growth is completed, the temperature is slowly lowered to room temperature at a cooling rate of 10°C / h, and the prepared crystal is taken out from the quartz crucible in a dry environment.

[0060] The Cs3Ce prepared in this example 0.94 The powder X-ray diffraction pattern and X-ray excitation emission spectrum of the Br6:6%Sb scintillation crystal are similar to those of Example 1.

[0061] The embodiment of the present invention utilizes Sb 3+ Through the doping strategy, a scintillator with near-infrared luminescence is prepared, which has very important value in the field of radiation detection.

[0062] The above description is only a specific implementation mode of the present invention, but the protection scope of the present invention is not limited thereto. Any modifications, equivalent substitutions and improvements made by any technician familiar with the technical field within the technical scope disclosed by the present invention and within the spirit and principle of the present invention should be covered by the protection scope of the present invention.

Claims

1. A near-infrared scintillation crystal, characterized in that: The chemical formula of the scintillation crystal is: Cs3Ce 1-y X6:ySb, Wherein X is selected from at least one of Cl and Br; and the value range of y is 0.001≤y≤0.

06.

2. A method for preparing the near-infrared scintillation crystal according to claim 1, characterized in that: The crucible descent method is used for preparation, which specifically includes the following steps: (1) According to the chemical formula Cs3Ce 1-y The stoichiometric ratio of each element in X6:ySb is that CsX powder, CeX3 powder, and SbX3 powder are prepared in a glove box at a molar ratio of 3:1-y:y, and are fully mixed to form a raw material powder, wherein X is selected from at least one of Cl and Br; 0.01≤y≤0.06; (2) The raw material powder is placed in a quartz crucible with a capillary structure under an inert atmosphere and heated for 10 -3 ~10 -7 Baking the material at a vacuum degree of Pa and 150-250°C for 12-60 hours, and sealing the quartz crucible by welding after cooling down; (3) placing the sealed quartz crucible in a crucible descending furnace, and raising the temperature of the crucible descending furnace to 50 to 150° C. above the melting point of the raw material to completely melt the raw material powder; (4) adjusting the temperature of the bottom of the quartz crucible to the melting point of the crystal, controlling the temperature gradient of the growth interface of the crucible descending furnace to be 5 to 40°C / cm, and then descending the quartz crucible in the furnace body at a descending speed of 0.01 to 10 mm / h, and the crystal nucleates and grows from the capillary bottom of the crucible until the melt is completely solidified; (5) After the growth is completed, the temperature is slowly lowered to room temperature at a cooling rate of 0.1 to 40°C / h, and the prepared crystal is taken out from the quartz crucible in a dry environment.

3. The method for preparing a near-infrared scintillation crystal according to claim 2, characterized in that: In step (4), the descending speed of the quartz crucible is 0.4 to 1 mm / h.

4. The method for preparing a near-infrared scintillation crystal according to claim 2, characterized in that: In step (1), the purity of the raw material powder is ≥99.99%.

5. The method for preparing a near-infrared scintillation crystal according to claim 2, characterized in that: In step (2), the inert atmosphere is argon or nitrogen.

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