Scintillation Ceramics and Their Preparation Methods and Applications

Abstract

This application relates to the technical field of scintillator materials. Specifically, it relates to a scintillation ceramic and its preparation method and application. The general chemical composition formula of the scintillation ceramic is (Y x Gd 0.99‑x Ce 0.01 )3Al5O 12 , where 0.1 ≤ x ≤ 0.5. By using the combination of yttrium element, gadolinium element, cerium element, aluminum element and oxygen element and regulating the ratio between each element, the formed scintillation ceramic has the advantages of a stable lattice structure, high luminous efficiency, high light yield and short decay life, and has a wider application range.

Description

Technical Field

[0001] The present application relates to the technical field of scintillator materials, and in particular, to a scintillation ceramic, a preparation method thereof, and an application thereof. Background Art

[0002] A scintillation material is a functional material that can convert high-energy rays or particles into ultraviolet-visible light, and is mainly applied to fields such as nuclear science, security inspection, medical imaging, geological exploration, non-destructive testing, and environmental monitoring.

[0003] However, the existing scintillation materials have a long decay lifetime, a low light yield, a complex preparation process, and a high cost, which greatly limits the wide application of scintillation materials. Summary of the Invention

[0004] The purpose of the present application is to provide a scintillation ceramic, a preparation method thereof, and an application thereof, aiming to improve the technical problems of the existing scintillation materials, such as long decay lifetime, low light yield, and complex preparation process.

[0005] In a first aspect, the present application provides a scintillation ceramic, and the general chemical formula of the scintillation ceramic is (Y x Gd 0.99- x Ce 0.01 )3Al5O 12 , where 0.1 ≤ x ≤ 0.5.

[0006] By using the combination of yttrium (Y), gadolinium (Gd), cerium (Ce), aluminum (Al), and oxygen (O) elements and regulating the ratio between each element, the present application can form a scintillation ceramic with advantages such as a stable lattice structure, high luminous efficiency, high light yield, and short decay lifetime.

[0007] Among them, the reaction cross-section of the Gd element is large and can discriminate signals such as neutrons and gamma rays. The Y element is a rare earth element with a small radius, and the Y ion (Y 3+ ) is doped into the lattice structure of the scintillation ceramic, which is beneficial to improving the stability of the lattice structure of the scintillation ceramic, and 0.1 ≤ x ≤ 0.5 can ensure that the scintillation ceramic has a high light yield. The Ce ion (Ce 3+ ) is used as an activator of the scintillation material and has a large emission intensity, and can emit transitions from 5d-4f; and the decay time of Ce 3+ luminescence is short, which can meet the requirement of the scintillation material for a short decay time.

[0008] In some embodiments of the first aspect of the present application, the light yield of the scintillation ceramic is 10000-11000 ph / Mev.

[0009] The light yield of the scintillation ceramics provided by this application is relatively high, and it can be used as a neutron-sensitive material for wavelength-shifting optical fibers or Anger cameras, high-resolution (10 - 100 micrometer level) neutron imaging systems, and neutron detectors; alternatively, it can also be applied to X-ray detectors or gamma detectors, etc.

[0010] In a second aspect, this application provides a method for preparing scintillation ceramics. The mixture of raw materials is hot-pressed under vacuum conditions of 1400 - 1600 °C and 30 - 50 MPa for not less than 80 minutes according to the general chemical composition formula of the scintillation ceramics provided in the first aspect above, and then annealed.

[0011] This application prepares scintillation ceramics by annealing after hot pressing, which can form scintillation ceramics with advantages such as a stable lattice structure, high luminous efficiency, high light yield, and short decay lifetime. The preparation efficiency is high, the process is simple, and the cost is low, making it suitable for large-scale production applications.

[0012] In some embodiments of the second aspect of this application, the annealing step includes: annealing the hot-pressed product at 1350 - 1450 °C for 5 - 10 hours.

[0013] Annealing under the above conditions is beneficial to eliminating oxygen vacancies formed during the hot pressing process, which is further beneficial to improving the transmittance of the scintillation ceramics, and thus beneficial to improving the luminescence performance of the scintillation ceramics.

[0014] Optionally, the method for preparing scintillation ceramics further includes: after the annealing step, polishing the annealed product.

[0015] In some embodiments of the second aspect of this application, the method for preparing scintillation ceramics further includes: before the hot pressing step, sintering the mixture of raw materials at 1300 - 1500 °C for 8 - 15 hours.

[0016] Sintering the mixture of raw materials at 1300 - 1500 °C for 8 - 15 hours before hot pressing can not only make the mixture of raw materials preliminarily shaped for subsequent hot pressing steps, but also preliminarily form a ceramic phase for forming a more pure scintillation ceramic during subsequent hot pressing, which is beneficial to fully exerting the luminescence performance of the scintillation ceramics.

[0017] Optionally, the method for preparing scintillation ceramics further includes: before the sintering step, calcining the mixture of raw materials at 800 - 1000 °C for 4 - 6 hours.

[0018] Calcining the mixture of raw materials at 800 - 1000 °C for 4 - 6 hours before sintering can remove moisture and organic impurities in the mixture of raw materials, etc., which is beneficial to forming a more pure scintillation ceramic.

[0019] In some embodiments of the second aspect of the present application, the mixture of raw materials is the material passing through a sieve with a mesh size of 100-200.

[0020] The mixture of raw materials being the material passing through a sieve with a mesh size of 100-200 is conducive to obtaining a mixture of raw materials with smaller particle sizes, and thus is conducive to further improving the luminescence performance of the scintillation ceramic.

[0021] In some embodiments of the second aspect of the present application, the preparation steps of the mixture of raw materials include: ball-milling and mixing the raw materials at 350-450 rpm for 10-12 h.

[0022] In the above manner, the particle size of the mixture of raw materials can be made smaller and more uniform, and thus is conducive to improving the luminescence performance of the finally prepared scintillation ceramic.

[0023] Optionally, the diameter of the spheres used during ball-milling is 1-4 mm.

[0024] Optionally, the ball-milling is wet ball-milling, and the ball-milling medium used for wet ball-milling is absolute ethanol.

[0025] Optionally, when the ball-milling is wet ball-milling, the preparation steps of the mixture of raw materials further include: after ball-milling, drying the ball-milled product at 50-85 °C for 10-30 h.

[0026] After ball-milling, drying the ball-milled product at 50-85 °C for 10-30 h is conducive to reducing the agglomeration of the mixture of raw materials after wet ball-milling, and thus is conducive to avoiding the influence on the luminescence performance of the scintillation ceramic obtained by subsequent hot pressing due to the agglomeration of the mixture of raw materials.

[0027] In some embodiments of the second aspect of the present application, the preparation steps of the mixture of raw materials further include: before ball-milling, first grinding the raw materials for 60-80 min.

[0028] Before ball-milling, first grinding the raw materials for 60-80 min can make the mixing between the raw materials more uniform and sufficient.

[0029] In some embodiments of the second aspect of the present application, the heating rate during hot pressing is 5-10 °C / min.

[0030] The heating rate during hot pressing being 5-10 °C / min can not only make the reaction for forming the ceramic phase more sufficient, but also ensure the efficiency of hot pressing.

[0031] In a third aspect, the present application provides an application of the scintillation ceramic provided in the first aspect as above in the preparation of neutron detectors, neutron counters, spectrometers, X-ray detectors, and gamma detectors.

[0032] Due to the high luminous efficiency, high light yield and short decay lifetime of the scintillation ceramics provided by this application, they can be used as neutron-sensitive materials for wavelength-shifting optical fibers or Anger cameras, high-resolution (10 - 100 micron level) neutron imaging systems, and neutron detectors; alternatively, they can also be applied to X-ray detectors or gamma detectors, etc. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] To more clearly illustrate the technical solutions of the embodiments of this application, the following will briefly introduce the drawings required for the embodiments. It should be understood that the following drawings only show some embodiments of this application, and therefore should not be regarded as limiting the scope. For those of ordinary skill in the art, without creative efforts, other relevant drawings can also be obtained based on these drawings.

[0034] Figure 1 Shows the process flow chart of the preparation of the scintillation ceramics provided by this application.

[0035] Figure 2 Shows the X-ray diffraction patterns of the scintillation ceramics prepared in Example 1 and Comparative Example 1 of this application.

[0036] Figure 3 Shows the X-ray radiation luminescence spectra of the scintillation ceramics prepared in Example 1 and Comparative Example 1 of this application.

[0037] Figure 4 Shows the light yield diagrams of the scintillation ceramics prepared in Example 1, Example 9, and Comparative Example 1 of this application and the commercial Li-6 glass scintillator (GS20). DETAILED DESCRIPTION OF THE EMBODIMENTS

[0038] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the following will clearly and completely describe the technical solutions in the embodiments of this application. For those conditions not specified in the embodiments, they are carried out according to conventional conditions or the conditions recommended by the manufacturer. For the reagents or instruments not specified by the manufacturer, they are all conventional products that can be obtained through commercial purchase.

[0039] This application provides a kind of scintillation ceramics, and the general chemical composition formula of the scintillation ceramics is (Y x Gd 0.99-x Ce 0.01 )3Al5O 12 , where 0.1 ≤ x ≤ 0.5.

[0040] By using the combination of yttrium (Y), gadolinium (Gd), cerium (Ce), aluminum (Al), and oxygen (O) elements and regulating the ratio between each element, this application can form scintillation ceramics with advantages such as a stable lattice structure, high luminous efficiency, high light yield, and short decay lifetime.

[0041] The reaction cross-section of Gd element is relatively large and can discriminate signals such as neutrons and gamma rays.

[0042] Due to the thermal instability of Gd3Al5O 12 Y element is a rare earth element with a small radius. When Y 3+ is doped into the lattice structure of the scintillation ceramic, it is beneficial to improve the stability of the lattice structure of the scintillation ceramic. And 0.1 ≤ x ≤ 0.5 can ensure that the scintillation ceramic has a high light yield. If the value of x is less than 0.1, it is not conducive to the stability of the lattice structure of the scintillation ceramic; if the value of x is greater than 0.6, the light yield of the scintillation ceramic will decrease significantly.

[0043] Exemplarily, the value of x can be 0.1, 0.15, 0.2, 0.25, 0.3, 0.4 or 0.5, etc.

[0044] As an activator of the scintillation material, Ce element 3+ The emission of Ce ions mainly comes from the 5d-4f transition. This process is an electric dipole transition. This process is parity-allowed and the spin selection rule does not work either. Therefore, the emission intensity of Ce 3+ ions is very large. And the luminescence decay time of Ce 3+ is short, which can meet the requirement of the scintillation material for a short decay time.

[0045] Under the limitation of the above chemical composition general formula of the scintillation ceramic, a scintillation ceramic with a light yield of 10000 - 11000 ph / Mev can be formed, and the light yield is relatively high.

[0046] This application provides a preparation method of a scintillation ceramic. Figure 1 The following shows the process flow chart of the preparation of the scintillation ceramic provided by this application. Please refer to Figure 1 , and the preparation method of the scintillation ceramic includes:

[0047] S10, prepare raw materials.

[0048] According to the chemical composition general formula (Y x Gd 0.99-x Ce 0.01 )3Al5O 12 prepare raw materials; where 0.1 ≤ x ≤ 0.5.

[0049] By using the combination of yttrium (Y), gadolinium (Gd), cerium (Ce), aluminum (Al) and oxygen (O) elements and regulating the ratio between each element, this application can form a scintillation ceramic with advantages such as a stable lattice structure, high luminous efficiency, high light yield and short decay life.

[0050] In this application, the raw materials for preparing the scintillation ceramic are Y2O3, Gd2O3, Al2O3 and CeF3. The F element in CeF3 will form and be removed from the prepared scintillation ceramic material in the form of gas during the subsequent high-temperature hot pressing process. Therefore, the F element will not be present in the final scintillation ceramic.

[0051] It should be noted that in other feasible embodiments, the raw materials for preparing the scintillation ceramic are not limited to the above substances, as long as the selection of raw materials meets the general chemical composition formula of the scintillation ceramic defined in this application.

[0052] Furthermore, in this application, the purity of the raw materials used for preparing the scintillation ceramic is 99.99% or above (i.e., 4N level or above purity), which is beneficial to improving the purity of the subsequently prepared scintillation ceramic, reducing the light scattering centers inside the scintillation ceramic, and thus giving full play to the optical properties of the scintillation ceramic.

[0053] S20, Mix the raw materials to obtain a mixture of raw materials.

[0054] In this application, the step of mixing the raw materials includes: ball-milling and mixing the raw materials at 350 - 450 rpm for 10 - 12 h, which can make the particle size of the mixture of raw materials smaller and more uniform, and thus is beneficial to improving the luminescence performance of the finally prepared scintillation ceramic.

[0055] As an example, the rotation speed of the ball-milling and mixing can be 350 rpm, 370 rpm, 400 rpm, 420 rpm or 450 rpm, etc.; the time of the ball-milling and mixing can be 10 h, 11 h, 11.5 h or 12 h, etc.

[0056] Furthermore, the diameter of the spheres used during ball-milling is 1 - 4 mm, which can make the particle size of the mixture of raw materials smaller and more uniform. As an example, the diameter of the spheres used during ball-milling can be 1 mm, 2 mm, 2.5 mm, 3 mm or 4 mm, etc.

[0057] It should be noted that this application does not limit the material of the spheres used during ball-milling. For example, it can be high-purity alumina balls.

[0058] In this application, the ball-milling method adopts wet ball-milling, and the ball-milling medium used for wet ball-milling is anhydrous ethanol, which is beneficial to improving the effect of ball-milling and mixing.

[0059] Furthermore, when the ball-milling method adopts wet ball-milling, the ratio of the mass of the spheres used for ball-milling to the total mass of the raw materials and anhydrous ethanol is (5 - 10):1. As an example, the ratio of the mass of the spheres used for ball-milling to the total mass of the raw materials and anhydrous ethanol is 6:1.

[0060] Exemplarily, the purity of the absolute ethanol used during ball milling is of analytical reagent grade.

[0061] When the ball milling is wet ball milling, the preparation step of the raw material mixture further includes: after ball milling, drying the ball milled product at 50 - 85 °C for 10 - 30 h, which is beneficial to reducing the agglomeration of the raw material mixture after wet ball milling, and further beneficial to avoiding the influence on the luminescence performance of the scintillation ceramics obtained by subsequent hot pressing due to the agglomeration of the raw material mixture.

[0062] Exemplarily, the drying temperature after wet ball milling can be 50 °C, 55 °C, 60 °C, 70 °C or 85 °C, etc.; the drying time after wet ball milling can be 10 h, 15 h, 20 h, 25 h or 30 h, etc.

[0063] Furthermore, the drying method can be vacuum drying or electrothermal blast drying, etc. The drying effect of the above drying methods is good and the efficiency is high, and there is less agglomeration of the dried powder.

[0064] In this application, the step of mixing the raw materials further includes: before ball milling, first grinding the raw materials for 60 - 80 min, which can make the mixing between the raw materials more uniform and sufficient, so as to facilitate subsequent ball milling and mixing and improve the mixing effect.

[0065] Exemplarily, the time for grinding the raw materials can be 60 min, 65 min, 70 min, 75 min or 80 min, etc.

[0066] In this application, the step of mixing the raw materials further includes: after ball milling, sieving the ball milled product through a 100 - 200 mesh sieve, which is beneficial to removing some agglomerates after ball milling to obtain a raw material mixture with uniform particle size, beneficial to better reaction during subsequent hot pressing, and further beneficial to improving the luminescence performance of the scintillation ceramics.

[0067] Exemplarily, the mesh number of sieving can be 100 mesh, 120 mesh, 150 mesh, 180 mesh or 200 mesh, etc.

[0068] S30, calcine the raw material mixture.

[0069] In this application, calcine the raw material mixture at 800 - 1000 °C for 4 - 6 h, which can remove moisture, organic impurities, etc. in the raw material mixture, is beneficial to forming a more pure scintillation ceramic, to reducing the light scattering centers inside the scintillation ceramic, and further to giving full play to the optical performance of the scintillation ceramic.

[0070] Exemplarily, the calcination temperature can be 800 °C, 850 °C, 900 °C, 950 °C or 1000 °C, etc.; the calcination time is 4 h, 4.5 h, 5 h, 5.5 h or 6 h, etc.

[0071] Further, in the present application, the mixture of raw materials is calcined in an air atmosphere.

[0072] S40, sinter the mixture of raw materials.

[0073] In the present application, sintering the mixture of raw materials at 1300 - 1500 °C for 8 - 15 h can not only make the mixture of raw materials be preliminarily formed for subsequent hot pressing steps, but also preliminarily form a ceramic phase to form a purer scintillation ceramic during subsequent hot pressing, so as to reduce the light scattering centers inside the scintillation ceramic, which is beneficial to fully exert the luminescent properties of the scintillation ceramic.

[0074] Exemplarily, the sintering temperature can be 1300 °C, 1350 °C, 1400 °C, 1450 °C or 1500 °C, etc.; the sintering time can be 8 h, 10 h, 12 h, 13 h or 15 h, etc.

[0075] S50, hot press the mixture of raw materials.

[0076] In the present application, hot press the mixture of raw materials under vacuum conditions of 1400 - 1600 °C and 30 - 50 MPa for no less than 80 min. Under the above hot pressing conditions, it is beneficial to quickly prepare a scintillation ceramic with advantages such as a stable lattice structure, high luminous efficiency, high light yield and short decay lifetime. In addition, hot pressing can remove the miscellaneous peaks generated during sintering to form a preliminary phase, so as to prepare a purer scintillation ceramic.

[0077] Exemplarily, the hot pressing temperature can be 1400 °C, 1450 °C, 1500 °C, 1550 °C or 1600 °C; the hot pressing pressure can be 30 MPa, 35 MPa, 40 MPa, 45 MPa or 50 MPa, etc.

[0078] Further, the hot pressing time is 80 - 160 min. Exemplarily, the hot pressing time can be 80 min, 90 min, 100 min, 120 min, 150 min or 160 min, etc.

[0079] The vacuum degree during hot pressing is 5×10 -4 -10 -3 Pa, and the above conditions can be beneficial to ensure the performance of the scintillation ceramic.

[0080] In the present application, the heating rate during hot pressing is 5-10 °C / min, which can not only make the reaction for forming the ceramic phase more sufficient, but also ensure the efficiency of hot pressing. If the heating rate during hot pressing is too fast, the raw materials do not have enough time to react sufficiently, which is not conducive to ensuring the luminescence performance of the finally prepared scintillation ceramic; if the heating rate during hot pressing is too slow, the hot pressing step takes a long time.

[0081] S60, annealing the product after hot pressing.

[0082] In the present application, the product after hot pressing is annealed at 1350-1450 °C for 5-10 h. Annealing under the above conditions is beneficial to eliminating the oxygen vacancies formed during the hot pressing process, which is further beneficial to improving the transmittance of the scintillation ceramic and further beneficial to improving the luminescence performance of the scintillation ceramic.

[0083] Exemplarily, the annealing temperature can be 1350 °C, 1370 °C, 1400 °C, 1420 °C or 1450 °C, etc.; the annealing time can be 5 h, 5.5 h, 7 h, 8 h, 9 h or 10 h, etc.

[0084] Further, after the annealing step, it further includes polishing the product after annealing to make the surface of the scintillation ceramic flat and smooth.

[0085] The present application also provides an electronic device including the above-mentioned scintillation ceramic.

[0086] Since the scintillation ceramic provided by the present application has high luminous efficiency, high light yield and short decay lifetime, it can be used as a neutron-sensitive material for wavelength-shifting optical fibers or Anger cameras, high-resolution (10-100 micron level) neutron imaging systems, neutron detectors; or, it can also be applied to X-ray detectors or gamma detectors, etc.

[0087] The characteristics and properties of the scintillation ceramic and its preparation method of the present application are further described in detail below in conjunction with embodiments.

[0088] Example 1

[0089] This example provides a scintillation ceramic, and the general chemical composition formula of the scintillation ceramic is (Y 0.2 Gd 0.79 Ce 0.01 )3Al5O 12 , and it is prepared by the following steps:

[0090] (1) 0.1789 g of Y2O3, 1.1348 g of Gd2O3, 0.6734 g of Al2O3 and 0.0156 g of CeF3 were put into a mortar and ground and mixed for 60 min. The ground powder was put into a ball mill containing high-purity alumina balls with a diameter of 3 mm and absolute ethanol, and ball-milled and mixed at 350 rpm for 10 h. Then, the ball-milled material was dried in a blast dryer at 80 °C for 24 h, and then sieved through a 200-mesh nylon sieve to obtain a mixture of raw materials.

[0091] Among them, the purities of Y2O3, Gd2O3, Al2O3 and CeF3 were 99.99%; the ratio of the mass of the high-purity alumina balls to the total mass of the ground powder and absolute ethanol was 6:1.

[0092] (2) The mixture of raw materials obtained in step (1) was calcined in a muffle furnace under an air atmosphere at 800 °C for 4 h; then the calcined material was sintered in the muffle furnace at 1350 °C for 10 h.

[0093] (3) The product sintered in step (2) was heated in a vacuum hot press furnace at a heating rate of 10 °C / min to 1450 °C, and hot-pressed at a vacuum degree of 9×10 -4 Pa and a pressure of 30 Mpa for 2 h, and naturally cooled to room temperature after pressure relief.

[0094] (4) The product hot-pressed in step (3) was annealed in a muffle furnace at 1350 °C for 10 h, and after cooling, it was polished on both sides to a thickness of 1 mm to obtain a scintillation ceramic.

[0095] Example 2

[0096] This example provides a scintillation ceramic. The general chemical composition formula of the scintillation ceramic is (Y 0.1 Gd 0.89 Ce 0.01 )3Al5O 12 . The preparation steps of the scintillation ceramic provided in this example are basically the same as those of the scintillation ceramic provided in Example 1, except that in step (1), the raw materials are: 0.0871 g of Y2O3, 1.2447 g of Gd2O3, 0.6556 g of Al2O3 and 0.0152 g of CeF3.

[0097] Example 3

[0098] This example provides a scintillation ceramic. The general chemical composition formula of the scintillation ceramic is (Y 0.5 Gd 0.49 Ce 0.01 )3Al5O 12, the preparation steps of the scintillation ceramic provided in this embodiment are basically the same as those of the scintillation ceramic provided in Embodiment 1, except that in step (1), the raw materials are: 0.4869 g of Y2O3, 0.7661 g of Gd2O3, 0.7329 g of Al2O3, and 0.0170 g of CeF3.

[0099] Embodiment 4

[0100] This embodiment provides a scintillation ceramic, and the general chemical composition formula of the scintillation ceramic is (Y 0.2 Gd 0.79 Ce 0.01 )3Al5O 12 , the preparation steps of the scintillation ceramic provided in this embodiment are basically the same as those of the scintillation ceramic provided in Embodiment 1, except that: in step (4), the annealing temperature is 1200 °C.

[0101] Embodiment 5

[0102] This embodiment provides a scintillation ceramic, and the general chemical composition formula of the scintillation ceramic is (Y 0.2 Gd 0.79 Ce 0.01 )3Al5O 12 , the preparation steps of the scintillation ceramic provided in this embodiment are basically the same as those of the scintillation ceramic provided in Embodiment 1, except that: this embodiment does not include the calcination step in step (2) of Embodiment 1.

[0103] Embodiment 6

[0104] This embodiment provides a scintillation ceramic, and the general chemical composition formula of the scintillation ceramic is (Y 0.2 Gd 0.79 Ce 0.01 )3Al5O 12 , the preparation steps of the scintillation ceramic provided in this embodiment are basically the same as those of the scintillation ceramic provided in Embodiment 1, except that: this embodiment does not include the sintering step in step (2) of Embodiment 1.

[0105] Embodiment 7

[0106] This embodiment provides a scintillation ceramic, and the general chemical composition formula of the scintillation ceramic is (Y 0.2 Gd 0.79 Ce 0.01 )3Al5O 12 , the preparation steps of the scintillation ceramic provided in this embodiment are basically the same as those of the scintillation ceramic provided in Embodiment 1, except that: in step (1), the ball milling speed is 200 rpm.

[0107] Embodiment 8

[0108] This embodiment provides a scintillation ceramic, and the general chemical composition formula of the scintillation ceramic is (Y 0.2 Gd 0.79 Ce 0.01 )3Al5O 12 . The preparation steps of the scintillation ceramic provided in this embodiment are basically the same as those of the scintillation ceramic provided in Embodiment 1, except that: the diameter of the high-purity alumina balls in step (1) is 10 mm.

[0109] Embodiment 9

[0110] This embodiment provides a scintillation ceramic, and the general chemical composition formula of the scintillation ceramic is (Y 0.2 Gd 0.79 Ce 0.01 )3Al5O 12 , and it is prepared by the following steps:

[0111] (1) Dissolve the powdery rare earth oxides (Gd2O3 and Y2O3) in nitric acid solution respectively, heat to dissolve and remove the excess nitric acid, and prepare 0.1 mol / L rare earth nitrate solutions respectively.

[0112] (2) According to the stoichiometric ratio (Y 0.2 Gd 0.79 Ce 0.01 )3Al5O 12 , measure the rare earth nitrate, Ce(NO3)3 and Al(NO3) solutions and mix them, add deionized water to make a solution with a volume of 100 ml, and stir for 10 min to make the mother salt solution evenly mixed.

[0113] (3) Weigh an appropriate amount of NH4HCO3 and dissolve it in deionized water, place it in a constant temperature water bath crucible, adjust the temperature to 30 °C and stir until NH4HCO3 is dissolved.

[0114] (4) Transfer the mother salt solution obtained in step (2) to a funnel, and drip the mother salt solution into the NH4HCO3 precipitant solution at a speed of 7 mL / min at room temperature to obtain a suspension. After the titration is completed, stir for 50 min.

[0115] (5) Centrifuge, wash and dry the suspension obtained in step (4) to obtain a precursor powder.

[0116] (6) Calcinate the precursor powder obtained in step (5) in a muffle furnace at 800 °C for 4 h to remove excess moisture and impurities.

[0117] (7) Load the powder obtained in step (6) into a mold with a diameter of 20 mm and perform cold isostatic pressing at 200 Mpa for 2 min.

[0118] (8) Load the ceramic green body obtained in step (7) into a vacuum furnace and sinter it at 1300 °C for 10 h to finally obtain (Y 0.2 Gd 0.79 Ce 0.01 )3Al5O 12 ceramics.

[0119] Comparative Example 1

[0120] This comparative example provides a scintillating ceramic, and the general chemical composition formula of the scintillating ceramic is (Y 0.6 Gd 0.39 Ce 0.01 )3Al5O 12 . The preparation steps of the scintillating ceramic provided in this comparative example are basically the same as those of the scintillating ceramic provided in Example 1, except that the raw materials in step (1) are: 0.6020 g of Y2O3, 0.6282 g of Gd2O3, 0.7552 g of Al2O3, and 0.0175 g of CeF3.

[0121] Comparative Example 2

[0122] This comparative example provides a scintillating ceramic, and the general chemical composition formula of the scintillating ceramic is (Y 0.2 Gd 0.79 Ce 0.01 )3Al5O 12 . The difference between the preparation steps of the scintillating ceramic provided in this comparative example and those of Example 1 is that the temperature for hot pressing in step (3) is 1000 °C.

[0123] Comparative Example 3

[0124] This comparative example provides a scintillating ceramic, and the general chemical composition formula of the scintillating ceramic is (Y 0.2 Gd 0.79 Ce 0.01 )3Al5O 12 . The difference between the preparation steps of the scintillating ceramic provided in this comparative example and those of Example 1 is that the pressure for hot pressing in step (3) is 10 MPa.

[0125] Comparative Example 4

[0126] This comparative example provides a scintillating ceramic, and the general chemical composition formula of the scintillating ceramic is (Y 0.2 Gd 0.79 Ce 0.01 )3Al5O 12 . The difference between the preparation steps of the scintillating ceramic provided in this comparative example and those of Example 1 is that this comparative example does not include the annealing treatment in step (4) of Example 1.

[0127] Experimental Example 1

[0128] The scintillating ceramics prepared in Example 1 and Comparative Example 1 were characterized by X-ray diffraction and X-ray radiation luminescence. The experimental results are as follows: Figure 2 and Figure 3 As shown; the scintillating ceramics prepared in Example 1, Example 9, Comparative Example 1 and the existing commercial Li-6 glass scintillator (GS20) were characterized for light yield, and the experimental results are as follows Figure 4 shown.

[0129] from Figure 2 It can be seen that the XRD diffraction peaks of the scintillating ceramics prepared in Example 1 and Comparative Example 1 are basically matched with the standard card YAG (PDF#33-0040).

[0130] However, from Figure 3 It can be seen that the luminous intensity of the scintillation ceramic prepared in Comparative Example 1 under X-ray radiation is significantly lower than that of the scintillation ceramic prepared in Example 1, indicating that the chemical composition formula (Y x G 0.99-x Ce 0.01 )3Al5O 12 Middle Y 3+ Too high a content of Gd 3+ When the amount is too little, the luminous intensity of the prepared scintillating ceramic is poor and the light yield is reduced.

[0131] from Figure 4 It can be seen that the pulse height spectrum of Li-6 glass scintillator has a channel number (CN GS20 ) is 600 channels, and the channel number (CN 实施例1 ) is 1100. It is known that the light yield of Li-6 glass scintillator (LY GS20 ) is 6000ph / Mev; According to the formula: LY 实施例1 =(CN 实施例1 / CN GS20 )LY GS20 The light yield (LY) of the scintillating ceramic prepared in Example 1 is 实施例1 ) is 11000ph / Mev; obviously, the light yield of the scintillating ceramic prepared in Example 1 of the present application (11000ph / Mev) is 1.83 times the light yield of the traditional Li-6 glass scintillator GS20 (6000ph / Mev). Therefore, the scintillating ceramic provided by the present application can replace the traditional GS20 glass.

[0132] Furthermore, the pulse height spectrum of the scintillating ceramics obtained in Example 1 has a channel number (CN 实施例1 ) is 1100 channels, and the channel number of the pulse height spectrum of the scintillating ceramic obtained in Example 9 (CN 实施例9 ) is 950, Figure 4The light yield (LY 实施例1 ) of the scintillation ceramic prepared in Example 1 is 11000 ph / Mev. According to the formula: LY 实施例9 =(CN 实施例9 / CN 实施例1 )LY 实施例1 , the light yield (LY 实施例9 ) of the scintillation ceramic prepared in Example 9 is 9500 ph / Mev, indicating that compared with the solution of Example 9, using the method of "vacuum hot pressing followed by annealing" in Example 1 to prepare the scintillation ceramic can further improve the light yield of the prepared scintillation ceramic.

[0133] The channel number (CN 实施例1 ) of the pulse height spectrum of the scintillation ceramic prepared in Example 1 is 1100 channels, and the channel number (CN 对比例1 ) of the pulse height spectrum of the scintillation ceramic prepared in Comparative Example 1 is 810 channels. Figure 4 It is known that the light yield (LY 实施例1 ) of the scintillation ceramic prepared in Example 1 is 11000 ph / Mev; according to the formula: LY 对比例1 =(CN 对比例1 / CN 实施例1 )LY 实施例1 , the light yield (LY 对比例1 ) of the scintillation ceramic prepared in Comparative Example 1 is 8100 ph / Mev. Obviously, the light yield (LY 对比例1 ) of the scintillation ceramic prepared in Comparative Example 1 is significantly lower than the light yield (LY 实施例1 ) of the scintillation ceramic prepared in Example 1, indicating that when the content of Y in the general chemical composition formula (Y x Gd 0.99-x Ce 0.01 )3Al5O 12 of the scintillation ceramic defined in this application is too high, the light yield of the prepared scintillation ceramic is not good.

[0134] Experimental Example 2

[0135] The light yield and decay lifetime of the scintillation ceramics prepared in Examples 1-9 and Comparative Examples 1-4 were characterized respectively, and the characterization results are shown in Table 1.

[0136] Table 1

[0137]

[0138] As can be seen from Table 1, the light yields of the scintillation ceramics prepared in Examples 1-8 are all higher than those of the materials prepared in Comparative Examples 1 to 4, indicating that the general chemical composition formula (Y x Gd 0.99-x Ce 0.01 )3Al5O12 (0.1 ≤ x ≤ 0.5) and the preparation method of the scintillation ceramics defined in the present application can effectively improve the light yield of the obtained materials.

[0139] From the comparison between Examples 1 - 3 and Comparative Example 1, it can be seen that when the chemical composition general formula of the scintillation ceramics is (Y x Gd 0.99- x Ce 0.01 )3Al5O 12 and the content of Y is too high and the content of Gd is too low, the light yield of the prepared scintillation ceramics is not good.

[0140] From the comparison between Example 1 and Comparative Examples 2 and 4, it can be seen that when the hot pressing temperature is low or annealing treatment is not carried out after hot pressing, it is impossible to prepare a phase corresponding to the standard card YAG (PDF#33 - 0040), so the obtained material does not have luminescent properties.

[0141] From the comparison between Example 1 and Comparative Example 3, it can be seen that when the hot pressing pressure is too low, the light yield of the prepared scintillation ceramics will also decrease significantly.

[0142] From the comparison between Example 1 and Examples 4 - 8, it can be seen that the annealing temperature, calcination before sintering, sintering before annealing, the rotation speed of ball milling and mixing, and the diameter of the balls can all further affect the light yield of the prepared scintillation ceramics.

[0143] From the comparison between Examples 1 - 8 and Example 9, it can be seen that using the method of "annealing after vacuum hot pressing" in the present application to prepare scintillation ceramics can further improve the light yield of the prepared scintillation ceramics.

[0144] In summary, the chemical composition general formula of the scintillation ceramics is (Y x Gd 0.99-x Ce 0.01 )3Al5O 12 , where 0.1 ≤ x ≤ 0.5. By using the combination of yttrium element, gadolinium element, cerium element, aluminum element and oxygen element in the present application and regulating the ratio between each element, the formed scintillation ceramics have advantages such as a stable lattice structure, high luminous efficiency, high light yield and short decay lifetime, and have a wider application range.

[0145] The above are only the preferred embodiments of the present application and are not used to limit the present application. For those skilled in the art, the present application can have various changes and modifications. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A method for preparing a scintillating ceramic, characterized in that, The general chemical composition formula of the scintillation ceramic is (Y x Gd 0.99- x Ce 0.01 )3Al5O 12 , where 0.1 ≤ x ≤ 0.5; The preparation method of the scintillation ceramic includes: successively calcining the mixture of raw materials at 800 - 1000 °C in an air atmosphere for 4 - 6 h, sintering at 1300 - 1500 °C in an air atmosphere for 8 - 15 h, hot pressing at 1400 - 1450 °C under a vacuum condition of 30 - 50 MPa for 80 - 160 min, and then annealing at 1350 - 1450 °C in an air atmosphere for 5 - 10 h.

2. The preparation method of the scintillation ceramic according to claim 1, wherein the preparation method of the scintillation ceramic further includes: after the annealing step, polishing the annealed product.

3. The preparation method of the scintillation ceramic according to claim 1, wherein The mixture of the raw materials is the material passing through a 100 - 200 mesh sieve.

4. The preparation method of the scintillation ceramic according to claim 1, characterized in that, The preparation step of the mixture of the raw materials includes: ball - milling and mixing the raw materials at 350 - 450 rpm for 10 - 12 h.

5. The preparation method of the scintillation ceramic according to claim 4, characterized in that, The diameter of the spheres used during the ball - milling is 1 - 4 mm.

6. The preparation method of the scintillation ceramic according to claim 4, wherein, The ball - milling is wet ball - milling, and the ball - milling medium used for the wet ball - milling is anhydrous ethanol.

7. The preparation method of the scintillation ceramic according to claim 4, characterized in that, When the ball - milling is wet ball - milling, the preparation step of the mixture of the raw materials further includes: after the ball - milling, drying the ball - milled product at 50 - 85 °C for 10 - 30 h.

8. The method for preparing the scintillation ceramic according to claim 7, wherein The preparation step of the mixture of the raw materials further includes: before the ball - milling, first grinding the raw materials for 60 - 80 min.

9. The preparation method of the scintillation ceramic according to claim 1, characterized in that, The heating rate during the hot pressing is 5 - 10 °C / min.

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