A LiF-CaF2:Eu-based organic / inorganic composite scintillator and its preparation method and application

Abstract

The present invention relates to a LiF-CaF2:Eu-based organic / inorganic composite scintillator and its preparation method and application. The LiF-CaF2:Eu-based organic / inorganic composite scintillator includes: an organic matrix, and a powdery LiF-CaF2:Eu inorganic scintillator dispersed in the organic matrix; the chemical composition of the powdery LiF-CaF2:Eu inorganic scintillator is (100-x)LiF·xCaF2·yEuF2, where 5≤x≤95 and 0.001%≤y / x≤2%.

Description

Technical Field

[0001] The present invention relates to a LiF-CaF2:Eu based organic / inorganic composite scintillator and a preparation method and application thereof, in particular to a composite scintillator formed by uniformly dispersing powdered LiF-CaF2:Eu inorganic scintillator into an organic matrix and a preparation method and application thereof, belonging to the field of scintillators for radiation detection. Background Art

[0002] With the deepening of research and application of thermal neutron technology, the demand for thermal neutron detection materials in countries around the world is increasing in both quantity and function, and higher requirements are also put forward for thermal neutron detection materials: 1) large neutron capture cross section; 2) high light output; 3) good energy resolution; 4) high α / β ratio; 5) high physicochemical stability; 6) low preparation cost.

[0003] Commonly used thermal neutron detection materials are 3 He gas, 6 LiF / ZnS:Ag mixed powder and 6 Li glass, 6 LiI:Eu crystal, CLYC:Ce crystal and CLLB:Ce crystal, etc. 3 He gas supply crisis, high supply and high price, urgent need to find alternatives; 6 Although Li glass has low cost, it has prominent problems such as small neutron capture cross section and low light output; 6 Inorganic single crystal materials such as LiI(Eu), CLYC:Ce, and CLLB have advantages such as good transparency, high light output, and high α / β ratio, but they have many problems such as poor physical and chemical stability, high cost, and difficulty in crystal preparation. As a commonly used thermal neutron detection material, 6 LiF / ZnS:Ag mixed powder can be used at low cost and in large areas, but the mixed powder is 6 The mechanical mixture of LiF and ZnS:Ag powders is 6 The refractive index difference of LiF is very large, making the mixture completely opaque and can only be used in the form of a thin sheet or coating on the surface, making its thermal neutron detection efficiency extremely low. In order to meet the urgent need for large-scale, low-cost thermal neutron detection, it is urgent to develop a new type of scintillator for thermal neutron detection.

[0004] Since LiF and CaF2 have almost the same refractive index (1.40 and 1.44) at a wavelength of 435nm, K. Watanabe et al. (Nucl. Instrum. Meth. A 954 (2020) 161244) tried to directly mix LiF and CaF2:Eu powders, and then added liquid glass resin to the mixed powders to obtain a translucent scintillator containing LiF, CaF2:Eu and liquid glass resin. LiF powder is a unit for thermal neutron absorption and generation of α particles, while CaF2:Eu is a scintillation luminescence unit. Since the transparency of the obtained mixture is higher than that of the original material, the scintillator can be used to generate α particles. 6 The LiF / ZnS:Ag mixture has a high concentration of scintillation light, which is more likely to be transmitted from the LiF / CaF2:Eu mixture and captured by the photosensitive device to detect thermal neutrons. 6 The energy of Li absorbing α particles can only emit scintillation light if it is transferred to CaF2:Eu particles. Since LiF and CaF2:Eu powders are separate solid particles with large gaps between particles, and there may be liquid glass resin between the two, and the range of charged α particles in the solid is about tens of μm, the energy transfer efficiency between the solid particles that absorb thermal neutrons and scintillate is very low, resulting in weak luminescence and low thermal neutron detection efficiency of the mixed scintillator prepared by this method. In addition, liquid glass resin is used in the production of this type of scintillator, and LiF and CaF2:Eu particles will gradually settle due to gravity and may become opaque again, limiting the practical application of the mixed scintillator of LiF, CaF2:Eu and liquid glass resin in the fields of thermal neutron detection and imaging. Summary of the invention

[0005] To this end, the purpose of the present invention is to first solid-phase sinter or crystal grow LiF, CaF2, EuF3 powder to form a LiF-CaF2:Eu solid solution containing a thermal neutron absorbing element ( 6 Li) and the scintillation luminescence unit CaF2:Eu, 6 The energy of alpha particles generated by Li after absorbing thermal neutrons can be efficiently transferred to CaF2:Eu in the solid solution; the solid solution is powdered and mixed with an organic matrix, and after dispersion, degassing and solidification, the bubbles introduced in the composite are eliminated to obtain a LiF-CaF2:Eu organic / inorganic composite scintillator with good stability and high transparency. This patent will provide a large-area, high-detection efficiency, strong luminescence, flexible organic / inorganic composite scintillator and its low-cost, high-efficiency preparation method, which can be used in the field of radiation detection including but not limited to thermal neutron detection.

[0006] First, the present invention provides a LiF-CaF2:Eu based organic / inorganic composite scintillator, comprising: an organic matrix, and a powdered LiF-CaF2:Eu inorganic scintillator dispersed in the organic matrix, wherein the content of the LiF-CaF2:Eu inorganic scintillator is 0.01 to 80 wt%.

[0007] The transmittance of the organic matrix in the wavelength range of 400-550 nm is ≥80%, and the refractive index is between 1.4 and 1.6.

[0008] The chemical composition of the powdered LiF-CaF2:Eu inorganic scintillator is (100-x)LiF·xCaF2·yEuF2, wherein 5≤x≤95, 0.001%≤y / x≤2%. The particle size of the powdered LiF-CaF2:Eu inorganic scintillator is 0.01-500 μm, preferably 0.05-10 μm.

[0009] The thickness of the LiF-CaF2:Eu-based organic / inorganic composite scintillator is 0.005 to 50 mm, preferably 0.05 to 1 mm.

[0010] Furthermore, the present invention also provides a method for preparing LiF-CaF2:Eu based inorganic scintillator powder, comprising the following processes: (1) weighing and mixing LiF, CaF2 and EuF3 powders according to the stoichiometric ratio of (100-x):x:y to obtain a mixed powder; or synthesizing a mixed powder of LiF, CaF2 and EuF3 in the stoichiometric ratio of (100-x):x:y by chemical coprecipitation method; wherein 5≤x≤95, 0.001%≤y / x≤2%; (2) subjecting the obtained mixed powder to solid phase sintering or crystal growth process to prepare a bulk LiF-CaF2:Eu solid solution inorganic scintillator; (3) preparing the obtained bulk LiF-CaF2:Eu solid solution inorganic scintillator into a powdered LiF-CaF2:Eu inorganic scintillator, the powder particle size of which is 0.01 to 500 μm, preferably 0.05 to 10 μm. (4) After mixing the powdered LiF-CaF2:Eu inorganic scintillator with the organic matrix, the mixture is dispersed and degassed to obtain a suspended or colloidal organic / inorganic composite scintillator premix; preferably, the organic matrix is ​​pre-solidified before the dispersion and degassing; (5) the obtained organic / inorganic composite scintillator premix is ​​heat-treated to completely solidify it.

[0011] Preferably, the particle size of the LiF, CaF2 and EuF3 powders is 0.01 to 500 μm, preferably 0.05 to 10 μm; the purity of the LiF, CaF2 and EuF3 powders is ≥ 99.9%, preferably the powder purity is ≥ 99.99%; 6The Li isotope abundance may be the natural abundance (7.5%), preferably an enriched abundance of 10% or more.

[0012] Preferably, the solid-phase sintering process includes: mixing the obtained mixed powder with a deoxidizer and then loading it into a crucible; placing the crucible in an inert atmosphere or a vacuum atmosphere or directly sealing it, first keeping it at 600-750°C for 1-5 hours, then sintering it at 800-1300°C for 1-10 hours, and cooling it to room temperature to obtain a bulk LiF-CaF2:Eu inorganic scintillator.

[0013] Preferably, the crystal growth process includes: 1) mixing the obtained mixed powder with a deoxidizer and loading it into a crucible; 2) placing the crucible in an inert atmosphere, a vacuum atmosphere or directly sealing it, first keeping it at 600-750°C for 1-5 hours, then sintering it at 800-1400°C for 1-10 hours, and then growing crystals at a growth rate of 0.1-10 mm / hour to obtain a bulk LiF-CaF2:Eu inorganic scintillator.

[0014] Preferably, the deoxidizer is selected from at least one or more of activated carbon, polytetrafluoroethylene, lead fluoride, ammonium bicarbonate and cadmium fluoride, and the added amount is 0.05-5wt% of the mixed powder or the mixed powder mass.

[0015] The LiF-CaF2:Eu based composite scintillator and preparation method of the present invention have the advantages of low cost, variable shape, large-area preparation and easy batch production.

[0016] Finally, the present invention provides an application of a LiF-CaF2:Eu based organic / inorganic composite scintillator in the field of radiation detection. This type of scintillator can be used in radiation detection fields including but not limited to neutron / X-ray / proton and gamma ray, and can be used in a fixed shape or a flexible, amorphous shape.

[0017] Unlike the existing technology of mechanically mixing LiF and CaF2:Eu powders and then filling them with liquid glass resin, this patent first mixes the initial raw materials of LiF, CaF2 and EuF3, and then forms a LiF-CaF2:Eu solid solution through solid phase sintering or crystal growth process. 3+ Reduced to Eu 2+ Replace part of Ca 2+ Then the bulk LiF-CaF2:Eu solid solution scintillator is made into powder and evenly dispersed into Eu 2+ A luminescent and transparent organic matrix is ​​formed to obtain a LiF-CaF2:Eu based organic-inorganic composite scintillator.

[0018] The present invention has the following advantages:

[0019] (1) The average effective distance between the LiF unit that absorbs thermal neutrons and the CaF2:Eu unit that emits scintillation light is much smaller than that of the mechanically mixed powder. 6 The energy of alpha particles generated by Li absorbing thermal neutrons is transferred to the CaF2:Eu unit with higher efficiency, so that a thicker and more transparent scintillator can be prepared, thereby achieving higher thermal neutron detection efficiency. The present invention can effectively solve the problems of large effective spacing between LiF and CaF2:Eu units and low energy transfer efficiency in the existing LiF / CaF2:Eu mixed scintillator, as well as the application bottleneck of low detection efficiency caused by poor transparency of the LiF / ZnS:Ag system;

[0020] (2) The organic matrix plays a role in supporting the inorganic scintillator powder and eliminating the air interface, and participates in the scintillation process to a lesser extent; however, the existing liquid glass resin separates the LiF element that absorbs thermal neutrons from the CaF2:Eu element that emits scintillation light. The energy of the α particles emitted by the LiF element after absorbing thermal neutrons generally needs to pass through the liquid glass resin before it can be transferred to the CaF2:Eu element. Due to the short range of the α particles, the energy loss in the process is extremely high, resulting in a very low luminous efficiency;

[0021] (3) It can realize the low-cost and high-efficiency preparation of large-sized, special-shaped and flexible scintillators that are sensitive to thermal neutrons. It has the characteristics of simple equipment, low cost and easy mass production, and can meet the detection applications of large areas and high detection efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 The left side is a photo of the LiF-CaF2:Eu inorganic scintillator prepared by solid phase sintering in Example 1, and the right side is a photo of the LiF-CaF2:Eu inorganic scintillator prepared by crystal growth in Example 6. The light transmittance of the sample prepared by the crystal growth process is slightly better than that of the sample prepared by solid phase sintering;

[0023] Figure 2 The composite scintillator series samples are obtained by heating and polymerizing the LiF-CaF2:Eu inorganic scintillator and the epoxy organic matrix in Examples 1-5, and the thickness is 1 mm. It can be seen from the figure that the transparency of the sample decreases with the increase of the inorganic filling amount;

[0024] Figure 3 The left side of the middle is the scintillator sample prepared by mechanically mixing LiF and CaF2:Eu powders and then compounding with an organic matrix in Comparative Example 1, with a thickness of 1 mm, and the transparency of the sample is poorer than that of the sample with the same inorganic / organic mass ratio in Example 2; the right side is the composite scintillator sample prepared without a prepolymerization process in Comparative Example 2, with a thickness of about 4 mm, and the inorganic scintillator powder and the organic matrix in the sample are clearly stratified;

[0025] Figure 4This is a scanning electron microscope image of LiF-CaF2:Eu after solid phase sintering, where the molar ratio of LiF:CaF2 is 0.8:0.2, and the prepared LiF-CaF2:Eu solid solution has an obvious periodic layered structure;

[0026] Figure 5 is the X-ray excited luminescence (XEL) spectrum of the composite scintillator sheet (1 mm thick) in Example 1-5, and the XEL spectrum intensity increases with the increase of the filling amount of the inorganic scintillator powder;

[0027] Figure 6 The optical transmission spectra of the composite scintillators with different LiF-CaF2:Eu filling amounts prepared in Examples 1-5, the optical transmission performance of the composite scintillators deteriorates with the increase of the filling amount of the inorganic scintillator powder;

[0028] Figure 7 The XEL spectra of the composite scintillators (thickness 1 mm) prepared in Example 2 and Comparative Example 1 show that the radioluminescence performance of the samples prepared by solid phase sintering is better than that of the samples prepared by mechanical mixing;

[0029] Figure 8 The optical transmittance spectra of the composite scintillators (1 mm thick) prepared in Examples 2 and 7 and Comparative Example 1 show that the optical transmittance characteristics of the samples prepared by solid-phase sintering and crystal growth processes are significantly better than those prepared by mechanical mixing, while the crystal growth process has a longer cycle than the solid-phase sintering process, and there may be non-uniform phenomena caused by oxidation and melt stratification, which makes its transmittance worse than that of solid-phase sintering;

[0030] Fig. 9 XEL spectra of composite scintillators (1 mm thick) with different LiF / CaF2 ratios prepared in Examples 2, 11, 12, 13 and 14, wherein the Eu / Ca ratio remains unchanged, and the luminescence intensity of the composite scintillator gradually increases with the increase of the CaF2 ratio;

[0031] Fig.10 The XEL spectra of the composite scintillators (thickness 1 mm) with different Eu-doped amounts prepared in Examples 15, 16, 17, 18 and 19. The XEL luminescence intensity has a concentration quenching effect of Eu-doping, and the optimal concentration is about 0.02%. DETAILED DESCRIPTION

[0032] The present invention is further described below by the following embodiments. It should be understood that the following embodiments are only used to illustrate the present invention, but not to limit the present invention.

[0033] In the early exploration, the inventors tried to prepare inorganic scintillating powder directly by mechanically mixing LiF, CaF2 and EuF3 raw material powders, and then mixed them with organic matrix to prepare composite scintillator. However, the prepared composite scintillator has low transparency and poor luminescence performance, and only CaF2 self-trapped exciton luminescence and EuF3 luminescence can be obtained. 3+ Problems such as 4f-4f transition luminescence.

[0034] To this end, this patent proposes to prepare a LiF-CaF2:Eu bulk scintillator in the form of a solid solution compound by pre-sintering or crystal growth of three powders of LiF, CaF2 and EuF3, wherein Eu 2+ Ion (Eu 3+ Enter the CaF2 lattice, replacing Ca 2+ After you become Eu 2+ ) enters CaF2 to replace part of Ca 2+ The ion lattice produces 4f-5d transition luminescence. The obtained block scintillator is then made into powder and combined with an organic matrix to obtain a large-sized, special-shaped composite scintillator; wherein the mass ratio of the inorganic scintillator to the organic matrix is ​​0.01wt% to 80wt%, and the actual mass ratio can be flexibly adjusted according to actual needs.

[0035] After the powders of LiF, CaF2 and EuF3 with a particle size of 0.01 to 500 μm are fully dried, they are weighed and mixed according to the stoichiometric ratio of (100-x): x: y; or LiF, CaF2 and EuF3 mixed powders synthesized by chemical coprecipitation method according to the stoichiometric ratio of (100-x): x: y are fully dried; wherein 5≤x≤95, 0.001%≤y / x≤2% (preferably 0.001%≤y / x≤1%). The maximum value of y / x is 2%, because too high Eu concentration will cause concentration quenching; experiments have also been conducted in this patent, please see Examples 15, 16, 17, 18 and 19 for details, and see the accompanying drawings Fig.10 .

[0036] In an optional embodiment, the purity of LiF, CaF2 and EuF3 powders is not less than 99.9%, preferably ≥ 99.99%; the mixed powder is subjected to a solid phase sintering or crystal growth process to prepare a bulk LiF-CaF2:Eu inorganic scintillator to form a uniform solid solution phase of LiF-CaF2:Eu, and the mixture is cooled to room temperature to obtain a bulk LiF-CaF2:Eu inorganic scintillator.

[0037] In an optional embodiment, a solid phase sintering process can be used to prepare a bulk LiF-CaF2:Eu solid solution inorganic scintillator. A mixed powder of LiF, CaF2 and EuF3 is mixed with a certain amount of a deoxidizer (such as activated carbon, polytetrafluoroethylene, lead fluoride, ammonium bicarbonate and cadmium fluoride, etc.) and then loaded into a crucible, wherein the deoxidizer is selected to be added in an amount of 0.05-5wt% of the mass of the mixed powder. The crucible is placed in an inert or vacuum atmosphere, or the crucible is directly sealed, and the crucible is heated to 600-750°C and kept warm for 1-5 hours so that Eu 3+ In the reducing atmosphere formed by the deoxidizer, it is reduced to Eu 2+ The crucible is sintered at 800-1400° C. for 1-10 hours to form a solid solution phase of LiF-CaF2:Eu scintillator, and then cooled to room temperature to obtain a bulk LiF-CaF2:Eu inorganic scintillator.

[0038] In an optional embodiment, a bulk LiF-CaF2:Eu solid solution inorganic scintillator can be prepared by a crystal growth process. A mixed powder of LiF, CaF2 and EuF3 is mixed with a certain amount of a deoxidizer (such as activated carbon, polytetrafluoroethylene, lead fluoride, ammonium bicarbonate and cadmium fluoride, etc.) and then loaded into a crucible, wherein the mass of the deoxidizer added is 0.05-5wt% of the mass of the mixed powder. The crucible is placed in an inert or vacuum atmosphere or sealed, and sintered at 800-1400°C for 1-10 hours, so that LiF and CaF2:Eu are evenly distributed in the melt; then crystal growth is performed at a rate of 0.1-10 mm / hour, and the mixture is cooled to room temperature to obtain a bulk LiF-CaF2:Eu inorganic scintillator.

[0039] In the present disclosure, LiF-CaF2:Eu inorganic scintillator powder with a particle size of 0.005 to 500 μm is uniformly dispersed in an organic matrix by mixing and degassing to obtain a uniform LiF-CaF2:Eu-based organic / inorganic composite scintillator. The resulting composite scintillator can be made into regular shapes such as flakes and blocks for application, or it can be made into flexible, amorphous shapes for application according to detection requirements, and it can also be made into a large-area detection screen and attached to the surface of other objects for application. The LiF-CaF2:Eu-based composite scintillator of the present invention has outstanding advantages such as good transparency, excellent scintillation performance, low cost, large-area preparation and easy batch production. The composite scintillator can be used in radiation detection fields including but not limited to neutrons, X-rays, protons and gamma rays.

[0040] Before preparing the LiF-CaF2:Eu-based organic / inorganic composite scintillator, the bulk LiF-CaF2:Eu inorganic scintillator needs to be first made into LiF-CaF2:Eu inorganic scintillator powder with a particle size of 0.01 to 500 μm, and then mixed with the organic matrix. Impurities and LiF-CaF2:Eu inorganic scintillator powder with a particle size that does not meet the requirements can be filtered out through a nylon sieve.

[0041] In an optional embodiment, the organic matrix has an optical transmittance of ≥80% in the 400-550 nm band and a refractive index between 1.4 and 1.6. For example, the organic matrix may be selected from 301-1, At least one of 301-2, etc.

[0042] The LiF-CaF2:Eu inorganic scintillator powder is uniformly mixed with a certain amount of organic matrix, and then the mixture is placed in a dispersion and degassing mixer for uniform dispersion and degassing to obtain a composite scintillator premix in a suspended or colloidal state. The dispersion and degassing can be carried out in the atmosphere or inert atmosphere, or in a vacuum environment, preferably in a vacuum environment and an inert atmosphere. Preferably, between the mixing, dispersion and degassing, the organic matrix is ​​first placed in a blast drying oven at a certain temperature and reacted for 10 to 30 minutes to allow the epoxy organic matrix to undergo a certain degree of prepolymerization, so that the organic matrix undergoes prepolymerization, increases viscosity, and thereby inhibits the precipitation of high-density scintillator particles in organic matter, so that a composite scintillator is subsequently prepared.

[0043] Under a certain temperature and protective atmosphere, the composite scintillator premix in a suspended or colloidal state is solidified so that the inorganic powder is solidified or embedded in the organic matrix to obtain the LiF-CaF2:Eu-based composite scintillator. The curing operation is performed according to the characteristics of the organic matrix. In order to avoid the precipitation of the inorganic scintillator powder in the organic matrix, a pre-curing operation of the organic matrix can be adopted. As an example, after the mixing, dispersion and degassing are completed, the obtained mixture is placed in a blast drying oven, and the temperature is raised to 65-80°C at a heating rate of 1-10°C / hour. The reaction is carried out for 2-3 hours to completely polymerize and solidify the composite scintillator. After the curing is completed, the temperature is reduced to room temperature at a cooling rate of 1-10°C / hour.

[0044] After the composite scintillator is completely cooled, it can be opened to obtain a composite scintillator blank. The composite scintillator blank can be cut, ground and polished as needed to obtain the required LiF-CaF2:Eu-based organic / inorganic composite scintillator.

[0045] The shape of the LiF-CaF2:Eu-based organic / inorganic composite scintillator in the present invention can be a regular fixed shape, or a flexible and other amorphous and irregular shape, and the thickness can be 0.005mm-50mm. LiF-CaF2:Eu inorganic scintillator powder is uniformly dispersed in an organic matrix to form a composite scintillator, and the inorganic scintillator powder accounts for 1 to 80wt% by mass.

[0046] The present invention provides an application of a LiF-CaF2:Eu-based composite scintillator. (1) The composite scintillator can be applied to radiation detection fields such as thermal neutrons, X-rays and protons, and is particularly suitable for low-cost, large-area radiation detection and imaging fields; (2) The composite scintillator can be made into regular shapes such as sheets and blocks for application, or can be made into flexible, amorphous shapes for application according to detection requirements, and can also be made into a large-area detection screen and attached to the surface of other objects for application.

[0047] 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 understood 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 belong to the scope of protection of the present invention. The specific process parameters and the like in the following examples are also only examples within a suitable range, that is, those skilled in the art can make a selection within a suitable range through the description herein, and are not limited to the specific values ​​​​exemplified below.

[0048] Example 1

[0049] (1) According to the stoichiometric ratio of 80:20:0.02, fully dried LiF (43.42 g), CaF2 (32.56 g) and EuF3 (0.0871 g) powder raw materials were weighed, and 0.6 wt % of polytetrafluoroethylene powder was added as a deoxidizer, and then the powders were fully mixed in a planetary mixer to obtain a mixed powder;

[0050] (2) the mixed powder is placed in a crucible, and then the crucible is directly sealed and placed in a tube furnace, the tube furnace is evacuated to a vacuum, and then the temperature is increased to 650° C. at a rate of 4° C. / hour, and then the temperature is increased to 1000° C. after being kept at this temperature for 2 hours, and the temperature is maintained for sintering for 2 hours;

[0051] (3) Cooling to room temperature to obtain bulk LiF-CaF2:Eu inorganic scintillator, and removing surface impurities with deionized water and alcohol;

[0052] (4) grinding the blocky inorganic scintillator in a mortar, filtering out impurities and scintillator particles whose particle size does not meet the requirements through a nylon sieve, and obtaining inorganic scintillator powder with a particle size of 0.1 to 500 μm;

[0053] (5) Place a certain amount of 301-1 organic epoxy glue, then put the glass bottle into a blast drying oven at a constant temperature of 60℃ and react for 10 minutes, so that the epoxy glue undergoes a certain degree of prepolymerization, significantly reducing its fluidity;

[0054] (6) Add 5 wt% of inorganic scintillator powder into a glass bottle and place it in a dispersion and degassing mixer for mixing, dispersion and degassing;

[0055] (7) Pour the evenly dispersed composite material into a mold, and then place the mold in a 65° C. forced air drying oven for 2 hours to allow the epoxy adhesive to completely polymerize; cool the mold, and remove the composite scintillator blank (thickness of about 3 mm) from the mold;

[0056] (8) Cutting, grinding and polishing the scintillator blank to obtain a 5wt% LiF-CaF2:Eu based composite scintillator.

[0057] Example 2

[0058] The preparation process of the LiF-CaF2:Eu composite scintillator in this Example 2 refers to that in Example 1, except that the filling amount of the LiF-CaF2:Eu inorganic scintillator powder is 10%.

[0059] Example 3

[0060] The preparation process of the LiF-CaF2:Eu composite scintillator in this embodiment 3 refers to that in embodiment 1, except that the filling amount of the LiF-CaF2:Eu inorganic scintillator powder is 20%.

[0061] Example 4

[0062] The preparation process of the LiF-CaF2:Eu composite scintillator in this Example 4 refers to that in Example 1, except that the filling amount of the LiF-CaF2:Eu inorganic scintillator powder is 40%.

[0063] Example 5

[0064] The preparation process of the LiF-CaF2:Eu composite scintillator in this Example 5 refers to that in Example 1, except that the filling amount of the LiF-CaF2:Eu inorganic scintillator powder is 60%.

[0065] Example 6

[0066] (1) Fully dried LiF (43.42 g), CaF2 (32.56 g) and EuF3 (0.0871 g) powder raw materials (purity: 99.99%) were weighed and mixed in a stoichiometric ratio of 80:20:0.02 to obtain a mixed powder, and 0.6 wt % of polytetrafluoroethylene was added as a deoxidizer, and the mixture was fully mixed and stirred in a planetary mixer to obtain a mixed powder;

[0067] (2) placing the mixed powder into a crucible, sealing the crucible and placing it into a crucible descending growth furnace, heating the growth furnace to 650° C. at a heating rate of 4° C. / hour and keeping the temperature for 2 hours, then heating the temperature to 1000° C. and keeping the temperature for 2 hours, growing crystals at a growth rate of 3-5 mm / hour, and cooling the growth furnace to room temperature after 12 hours of growth;

[0068] (3) Open the crucible to obtain a block of LiF-CaF2:Eu inorganic scintillator, and remove impurities on its surface with deionized water and alcohol;

[0069] (4) After the impurities are cleaned, a planetary ball mill is used to grind the impurities into inorganic scintillator powder with a particle size between 0.1 and 200 μm, and the impurities and scintillator particles whose particle size does not meet the requirements are filtered out through a nylon sieve;

[0070] (5) 301-1 organic epoxy adhesive was weighed and added to a glass bottle, and then the glass bottle was placed in a 60°C forced air drying oven for 10 minutes. At this time, the solution had been prepolymerized to a certain extent and had very low fluidity.

[0071] (6) putting the ground 5 wt% inorganic scintillator powder into a glass bottle and dispersing and degassing it in a dispersing and degassing mixer;

[0072] (7) Pour the evenly dispersed composite material into a square mold, then place the mold in a blast drying oven, raise the temperature to 65° C. at a heating rate of 5° C. / hour, react for 2 hours to allow the epoxy glue to completely polymerize, and cool to room temperature. After removing the mold, a composite scintillator blank (thickness of about 3 mm) is obtained;

[0073] (8) Cutting, grinding and polishing the scintillator blank to obtain a 5wt% LiF-CaF2:Eu based composite scintillator.

[0074] Example 7

[0075] The preparation process of the LiF-CaF2:Eu composite scintillator in this Example 7 refers to that in Example 6, except that the filling amount of the LiF-CaF2:Eu inorganic scintillator powder is 10%.

[0076] Example 8

[0077] The preparation process of the LiF-CaF2:Eu composite scintillator in this Example 8 refers to that in Example 6, except that the filling amount of the LiF-CaF2:Eu inorganic scintillator powder is 20%.

[0078] Example 9

[0079] The preparation process of the LiF-CaF2:Eu composite scintillator in this Example 9 refers to that in Example 6, except that the filling amount of the LiF-CaF2:Eu inorganic scintillator powder is 40%.

[0080] Example 10

[0081] The preparation process of the LiF-CaF2:Eu composite scintillator in this embodiment 10 refers to that in embodiment 6, except that the filling amount of the LiF-CaF2:Eu inorganic scintillator powder is 60%.

[0082] Embodiment 11

[0083] The preparation process of the LiF-CaF2:Eu composite scintillator in this Example 11 refers to Example 2, except that the contents of LiF, CaF2 and EuF3 are 56.94g, 19.04g and 0.0510g, respectively, so that the molar ratio of LiF:CaF2:EuF3 is 90:10:0.01.

[0084] Example 12

[0085] The preparation process of the LiF-CaF2:Eu composite scintillator in this Example 12 refers to Example 2, except that the contents of LiF, CaF2 and EuF3 are 33.24g, 42.74g and 0.1144g, respectively, so that the molar ratio of LiF:CaF2:EuF3 is 70:30:0.03.

[0086] Embodiment 13

[0087] The preparation process of the LiF-CaF2:Eu composite scintillator in this Example 13 refers to that in Example 2, the difference is that the contents of LiF, CaF2 and EuF3 are 25.33 g, 50.65 g and 0.1355 g, respectively, so that the molar ratio of LiF:CaF2:EuF3 is 60:40:0.04.

[0088] Embodiment 14

[0089] The preparation process of the LiF-CaF2:Eu composite scintillator in this Example 14 refers to Example 2, except that the contents of LiF, CaF2 and EuF3 are 18.95g, 57.03g and 0.1526g, respectively, so that the molar ratio of LiF:CaF2:EuF3 is 50:50:0.05.

[0090] Embodiment 15

[0091] The preparation process of the LiF-CaF2:Eu composite scintillator in this Example 15 refers to that in Example 2, except that the molar ratio of LiF:CaF2:EuF3 is 80:20:0.0004 (y / x=0.002%, recorded as 0.02% Eu).

[0092] Example 16

[0093] The preparation process of the LiF-CaF2:Eu composite scintillator in this Example 16 refers to that in Example 2, except that the molar ratio of LiF:CaF2:EuF3 is 80:20:0.002 (y / x=0.01%, recorded as 0.01% Eu).

[0094] Embodiment 17

[0095] The preparation process of the LiF-CaF2:Eu composite scintillator in this Example 17 refers to that in Example 2, except that the molar ratio of LiF:CaF2:EuF3 is 80:20:0.01 (y / x=0.05%, recorded as 0.05% Eu).

[0096] Embodiment 18

[0097] The preparation process of the LiF-CaF2:Eu composite scintillator in this Example 18 refers to that in Example 2, except that the molar ratio of LiF:CaF2:EuF3 is 80:20:0.04 (y / x=0.2%, recorded as 0.2% Eu).

[0098] Embodiment 19

[0099] The preparation process of the LiF-CaF2:Eu composite scintillator in this Example 19 refers to that in Example 2, except that the molar ratio of LiF:CaF2:EuF3 is 80:20:0.16 (y / x=0.8%, recorded as 0.8% Eu).

[0100] Embodiment 20

[0101] The preparation process of the LiF-CaF2:Eu composite scintillator in this embodiment 20 refers to that in embodiment 2, the difference is that: in step (5), an organic epoxy glue is used as 301-2.

[0102] Embodiment 21

[0103] The preparation process of the LiF-CaF2:Eu composite scintillator in this Example 20 refers to that in Example 2, except that the inorganic scintillator accounts for 70wt%.

[0104] Embodiment 22

[0105] The preparation process of the LiF-CaF2:Eu composite scintillator in this Example 20 refers to that in Example 2, except that the inorganic scintillator accounts for 80wt%.

[0106] Embodiment 23

[0107] The preparation process of the LiF-CaF2:Eu composite scintillator in this Example 20 refers to that in Example 2, except that the deoxidizer is activated carbon, and the added amount is 0.05wt%.

[0108] Embodiment 24

[0109] The preparation process of the LiF-CaF2:Eu composite scintillator in this Example 20 refers to that in Example 2, except that the amount of deoxidizer added is 1 wt%.

[0110] Embodiment 25

[0111] The preparation process of the LiF-CaF2:Eu composite scintillator in this Example 20 refers to that in Example 2, except that the amount of deoxidizer added is 5 wt%.

[0112] Comparative Example 1

[0113] (1) Fully dried 99.99% pure CaF2 (32.56 g) and EuF3 (0.0871 g) powder raw materials were weighed according to the stoichiometric ratio of 20:0.02, and 0.6 wt % of polytetrafluoroethylene powder was added as a deoxidizer, and the mixture was fully mixed and stirred in a planetary mixer to make the powders uniformly mixed;

[0114] (2) the mixed powder is placed in a platinum crucible, and then the crucible is directly sealed and placed in a tube furnace, the tube furnace is evacuated to a vacuum, and then the crucible is heated to 650° C. at a heating rate of 4° C. / hour for 2 hours, and then heated to 1400° C. for sintering for 2 hours;

[0115] (3) Cooling to room temperature to obtain a bulk CaF2:Eu scintillator, and removing impurities on the surface of the scintillator with deionized water and alcohol;

[0116] (5) After cleaning, use a planetary ball mill to grind it into a scintillator-free powder with a particle size between 0.1 and 200 μm, and filter out impurities and scintillator particles that do not meet the requirements through a nylon sieve;

[0117] (6) 32.65 g of CaF2:Eu inorganic scintillator powder and 43.42 g of LiF (purity 99.99%) raw material powder were fully dried and stirred to make the molar ratio of LiF:CaF2 80:20, and the mixture was fully mixed;

[0118] (7) Load The glass bottle of 301-1 epoxy adhesive was placed in a 60°C forced air drying oven and allowed to react for 10 minutes, so that the epoxy adhesive was prepolymerized and had very low fluidity.

[0119] (8) putting the ground 10 wt% inorganic scintillator powder into a glass bottle containing epoxy glue, and dispersing and degassing in a dispersing and degassing mixer;

[0120] (9) pouring the evenly dispersed composite material into a square mold, and then placing the mold in a 65° C. forced air drying oven for 2 hours to allow the epoxy adhesive to completely polymerize, cooling the temperature to room temperature and removing the mold to obtain a composite scintillator blank with a thickness of about 3 mm;

[0121] (10) The scintillator blank is cut, ground and polished to obtain a 10 wt % LiF-CaF2:Eu based composite scintillator.

[0122] Comparative Example 2

[0123] The preparation process of the LiF-CaF2:Eu composite scintillator in this comparative example 2 refers to that of Example 3, except that no prepolymerization treatment is performed in step (6).

[0124] Table 1 shows the raw material ratio and preparation process of the LiF-CaF2:Eu composite scintillator prepared by the present invention:

[0125]

[0126]

[0127] To facilitate a full understanding of this patent, the specific embodiments of the present invention are described above, and some specific technical details and processes are given. It can be implemented in other ways different from the description herein. Those skilled in the art can make similar extensions or modifications without violating the scope of the claims of this patent, and these contents should be covered within the scope of protection of this patent.

Claims

1. A LiF-CaF2:Eu based organic / inorganic composite scintillator, characterized in that: The LiF-CaF2:Eu-based organic / inorganic composite scintillator comprises: an organic matrix, and a powdered LiF-CaF2:Eu solid solution inorganic scintillator dispersed in the organic matrix and obtained through solid phase sintering or crystal growth process; the chemical composition of the powdered LiF-CaF2:Eu solid solution inorganic scintillator is (100-x)LiF·xCaF2·yEuF2, wherein 5≤x≤95, 0.001%≤y / x≤2%; the preparation method of the powdered LiF-CaF2:Eu solid solution inorganic scintillator comprises: (1) weighing and mixing LiF, CaF2 and EuF3 powders according to the stoichiometric ratio of (100-x):x:y to obtain a mixed powder; or synthesizing a mixed powder of LiF, CaF2 and EuF3 in the stoichiometric ratio of (100-x):x:y by chemical coprecipitation; (2) subjecting the obtained mixed powder to a solid phase sintering or crystal growth process to prepare a bulk LiF-CaF2:Eu solid solution inorganic scintillator; the solid phase sintering comprises: mixing the obtained mixed powder with a deoxidizer and then loading it into a crucible, placing the crucible in an inert atmosphere or a vacuum atmosphere or directly sealing it at 600-750°C for 1-5 hours, and then sintering it at 800-1300°C for 1-10 hours; the crystal growth comprises: 1) mixing the obtained mixed powder with a deoxidizer and then loading it into a crucible; 2) placing the crucible in an inert atmosphere or a vacuum atmosphere or directly sealing it, firstly keeping it at 600-750°C for 1-5 hours, and then sintering it at 800-1400°C for 1-10 hours, and then growing it at a rate of 0.1-10 mm / hour; (3) The obtained bulk inorganic scintillator is made into a powdery inorganic scintillator.

2. The LiF-CaF2:Eu based organic / inorganic composite scintillator according to claim 1, characterized in that: The content of the powdered LiF-CaF2:Eu inorganic scintillator is 0.01-80wt%.

3. The LiF-CaF2:Eu based organic / inorganic composite scintillator according to claim 1, characterized in that: The particle size of the powdered LiF-CaF2:Eu inorganic scintillator is 0.01-500 μm.

4. The LiF-CaF2:Eu based organic / inorganic composite scintillator according to claim 3, characterized in that: The particle size of the powdered LiF-CaF2:Eu inorganic scintillator is 0.05-10 μm.

5. The LiF-CaF2:Eu based organic / inorganic composite scintillator according to any one of claims 1 to 4, characterized in that: The optical transmittance of the organic matrix in the 400-550nm band is ≥80%, and the refractive index is between 1.4 and 1.

6.

6. A method for preparing a LiF-CaF2:Eu based organic / inorganic composite scintillator according to any one of claims 1 to 5, characterized in that: The process includes the following: (1) weighing and mixing LiF, CaF2 and EuF3 powders according to the stoichiometric ratio of (100-x):x:y to obtain a mixed powder; or synthesizing a mixed powder of LiF, CaF2 and EuF3 in the stoichiometric ratio of (100-x):x:y by chemical coprecipitation; (2) subjecting the obtained mixed powder to a solid phase sintering or crystal growth process to prepare a bulk LiF-CaF2:Eu solid solution inorganic scintillator; the solid phase sintering comprises: mixing the obtained mixed powder with a deoxidizer and then loading it into a crucible, placing the crucible in an inert atmosphere or a vacuum atmosphere or directly sealing it at 600-750°C for 1-5 hours, and then sintering it at 800-1300°C for 1-10 hours; the crystal growth comprises: 1) mixing the obtained mixed powder with a deoxidizer and then loading it into a crucible; 2) placing the crucible in an inert atmosphere or a vacuum atmosphere or directly sealing it, firstly keeping it at 600-750°C for 1-5 hours, and then sintering it at 800-1400°C for 1-10 hours, and then growing it at a rate of 0.1-10 mm / hour; (3) preparing the obtained bulk inorganic scintillator into a powdery inorganic scintillator; (4) mixing the powdered LiF-CaF2:Eu inorganic scintillator with the organic matrix, and then dispersing and degassing the mixture to obtain a composite scintillator premix in a suspended or colloidal state; (5) The obtained composite scintillator premix is ​​subjected to heat treatment to completely solidify the premix, thereby obtaining the LiF-CaF2:Eu-based organic / inorganic composite scintillator.

7. The preparation method according to claim 6, characterized in that: Pre-solidification of the organic matrix prior to dispersion and degassing.

8. The preparation method according to claim 6, characterized in that: In step (1), the purity of the LiF, CaF2 and EuF3 powders is not less than 99.9%; the particle size of the Li, CaF2 and EuF3 powders is 0.01 to 500 μm; 6 Li isotopes are either natural abundance or enriched abundance.

9. The preparation method according to claim 8, characterized in that: The particle size of the Li, CaF2 and EuF3 powders in step (1) is 0.05 to 10 μm; 6 The enrichment abundance of Li isotope is more than 10%.

10. The preparation method according to claim 6, characterized in that: The deoxidizer is selected from at least one of activated carbon, polytetrafluoroethylene, lead fluoride, ammonium bicarbonate and cadmium fluoride, and the added amount of the deoxidizer is 0.05-5wt% of the mass of the mixed powder.

11. Use of the LiF-CaF2:Eu based organic / inorganic composite scintillator according to any one of claims 1 to 5 in radiation detection.

Images