A RbLiCl2-based scintillation material, its preparation method and application

Abstract

The present application relates to a kind of RbLiCl2-based scintillation material and its preparation method and application, belong to halide crystal scintillation material technical field.For the technical problems such as high growth difficulty of existing Li-containing halide scintillator material, energy resolution is limited, neutron / γ or α / γ pulse shape difference is insufficient, the present application provides a kind of luminescent ion doped RbLiCl2-based scintillation material and its preparation method, through the 1:1:2 stoichiometric ratio matrix design of RbLiCl2, light element Li neutron conversion center, heavy element Rb γ response center and the synergistic effect of multiple types of luminescent ion doping control, the unified construction of X-ray, γ-ray, α particle and neutron radiation response is realized, and the controllable optimization of material performance such as ionizing radiation luminescence response, emission wavelength, decay kinetics, light output, energy resolution and PSD is obtained, which can be applied to nuclear radiation detection and related detection device field.

Description

Technical Field

[0001] This invention belongs to the field of halide crystal scintillation materials technology, specifically relating to an RbLiCl2-based scintillation material and its preparation method and application. Background Technology

[0002] Neutrons, gamma rays, X-rays, and alpha particles are common forms of radiation used in nuclear energy utilization, nuclear material identification, radioactive source searching, reactor monitoring, high-energy physics experiments, space radiation monitoring, and medical imaging. Practical applications often involve mixed radiation fields, such as neutron fields accompanied by strong gamma background and alpha contamination monitoring accompanied by gamma background. Therefore, detection materials not only need high luminescence efficiency but also particle discrimination capabilities.

[0003] Li-containing scintillation materials can utilize 6 The Li(n,α)t nuclear reaction enables thermal neutron detection; the alpha particles and tritium nuclei produced in this reaction can deposit energy in a scintillator and generate a light signal. 3 Compared to He proportional counters, Li-containing scintillation crystals have the potential for miniaturization, arraying, solid-state fabrication, and composite detection. Existing Li halide scintillators such as Cs₂LiYCl₆:Ce, Cs₂LiLaBr₆:Ce, and Li co-doped NaI:Tl have already been applied in neutron / γ dual-mode detection, but still have varying degrees of limitations. For example, some materials are difficult to grow, suffer from severe deliquescence, have complex compositions, and are costly; self-absorption, defect trapping, and nonlinear responses in some materials limit energy resolution; and the neutron / γ or α / γ pulse shape differences in some materials are insufficient.

[0004] RbLiCl2 is a relatively simple Li halide matrix material containing Rb, Li, and Cl, and has the potential to construct neutron conversion centers for light elements and gamma-response centers for heavy elements. By introducing luminescent ions with different valence states and electronic configurations into this matrix, carrier trapping, exciton localization, emission wavelength, decay kinetics, and particle discrimination capabilities can be tuned.

[0005] Therefore, it is necessary to propose an RbLiCl2-based scintillation material and its preparation method that can cover multiple luminescent ions, take into account crystal growthability, spectral tunability and mixed radiation field discrimination capability. Summary of the Invention

[0006] To address the aforementioned technical problems, the present invention aims to provide an RbLiCl2-based scintillation material, its preparation method, and its application.

[0007] In a first aspect, the present invention provides an RbLiCl2-based scintillation material, wherein the general chemical formula of the RbLiCl2-based scintillation material is Rb 1-a A a Li1-b M b Cl 2-c X c Or Rb 1-a A a Li 1-b M b Cl 2-c X c :D x ,in: A includes at least one of Na, K, and Cs; M includes at least one of Na, K, Mg, Ca, Sr, Ba, Zn, Cu, and Ag; X includes at least one of F, Br, and I; 0 ≤ a ≤ 0.5; 0 ≤ b ≤ 0.5; 0 ≤ c ≤ 1.0. D represents the luminescent ion and includes at least one of Tl, Ce, Pr, and Eu, and x represents the luminescent ion relative to Rb. 1- a A a Li 1-b M b Cl 2-c X c The molar doping ratio of the matrix is ​​0.00001≤x≤0.2.

[0008] Preferably, the Li in the RbLiCl2-based scintillation material includes naturally abundant Li, 6 Li enriched in Li.

[0009] Preferably, the morphology of the RbLiCl2-based scintillation material includes bulk single crystal, polycrystalline ceramic, thin film, microcrystalline powder, or composite screen; wherein, the bulk single crystal RbLiCl2-based scintillation material belongs to the orthorhombic crystal system and space group Cmcm.

[0010] Secondly, the present invention provides a method for preparing the above-mentioned RbLiCl2-based scintillation material, the method comprising the following steps: weighing and mixing raw materials according to the stoichiometric ratio of the chemical composition elements of the RbLiCl2-based scintillation material in an anhydrous and oxygen-free environment; then placing the mixed raw materials in a quartz ampoule or crucible for impurity removal; and then performing crystal growth by the Bridgman method, crucible lowering method, temperature gradient method or micro-pulling method to obtain the RbLiCl2-based scintillation material.

[0011] Preferably, the Bridgman process includes the following steps: placing the raw material powder in a quartz ampoule or crucible and evacuating and sealing it, then placing it in a crystal growth furnace, heating it to the highest raw material melting temperature and holding it at that temperature; then adjusting the height and position of the quartz ampoule or crucible, the furnace temperature, and the longitudinal temperature gradient of the crystal growth furnace, and lowering the quartz ampoule or crucible within the furnace to begin crystal growth; after growth is completed, cooling to room temperature to obtain the RbLiCl2-based scintillation material.

[0012] Preferably, the maximum melting temperature of the raw material is 550-850℃, and the holding time is 2-48 h.

[0013] Preferably, the longitudinal temperature gradient of the crystal growth furnace is 5-50℃ / cm, and the quartz ampoule or crucible descends at a rate of 0.01-10.0 mm / h within the furnace.

[0014] Preferably, the rate of cooling to room temperature is 0.5-50℃ / h.

[0015] Thirdly, the present invention provides an application of the above-mentioned RbLiCl2-based scintillation material in nuclear radiation detection, wherein the nuclear radiation detection includes neutron detection, alpha particle detection, gamma ray detection, X-ray imaging, alpha / gamma discrimination, neutron / gamma discrimination, nuclear material identification, reactor monitoring, homeland security inspection, space radiation monitoring, oil well logging, and medical imaging.

[0016] Beneficial effects This invention provides the first preparation and verification of a scintillation response in RbLiCl2-based single crystals. Samples represented by RbLiCl2:Tl exhibit significant emission at approximately 302 nm and display multi-component characteristics during pulse decay, with an average decay time of approximately 366 ns. 241 Under Am testing, α and γ events form a distinguishable distribution in the PSD ratio, with a PSD quality factor of approximately 1.3, indicating good particle discrimination potential. Attached Figure Description

[0017] Figure 1 Photographs of the crystal blanks and end faces of RbLiCl2-based samples under different luminescent ion doping conditions; Figure 2 Rb prepared in Example 1 0.99 LiCl2:Tl 0.01 X-ray emission spectrum of the sample; Figure 3 Rb prepared in Example 1 0.99 LiCl2:Tl 0.01 Photoluminescence excitation and emission spectra of the sample; Figure 4 Rb prepared in Example 1 0.99LiCl2:Tl 0.01 Sample in 241 Alpha and gamma mixed radiation pulse height spectrum tested under Am source; Figure 5 Rb prepared in Example 1 0.99 LiCl2:Tl 0.01 Sample in 241 Two-dimensional distribution of PSD ratio-ADC under Am source test; Figure 6 Rb prepared in Example 1 0.99 LiCl2:Tl 0.01 Sample in 241 Scintillation decay curves and multi-exponential fitting results under Am source; Figure 7 Rb prepared in Example 1 0.99 LiCl2:Tl 0.01 Sample in 241 PSD ratio projection and Gaussian fitting plot under Am source; Figure 8 Rb prepared in Example 1 0.99 LiCl2:Tl 0.01 Sample in 241 Comparison of the pulse height spectrum under Am source after selecting the α event ADC spectrum with the spectrum of all events; Figure 9 X-ray emission spectrum of RbLiCl2 sample; Figure 10 Rb prepared in Example 4 0.99 LiCl2:Ce 0.01 X-ray emission spectrum of the sample; Figure 11 Rb prepared in Example 5 0.99 LiCl2:Pr 0.01 X-ray emission spectrum of the sample; Figure 12 Rb prepared in Example 6 0.99 LiCl2:Eu 0.01 X-ray emission spectrum of the sample; Figure 13 Rb prepared in Example 2 0.99999 LiCl2:Tl 0.00001 Crystal photographs; Figure 14 Rb prepared in Example 3 0.8 LiCl2:Tl 0.2 Crystal photographs; Figure 15 Rb prepared in Example 7 0.98LiCl2:Tl 0.01 / Ce 0.01 Crystal photographs; Figure 16 Rb prepared in Example 8 0.98 LiCl2:Tl 0.01 / Pr 0.01 Crystal photographs; Figure 17 Rb prepared in Example 9 0.98 LiCl2:Tl 0.01 / Eu 0.01 Crystal photographs; Figure 18 Rb prepared in Example 10 0.98 LiCl2:Pr 0.01 / Ce 0.01 Crystal photographs; Figure 19 The RbLiCl prepared in Example 11 1.9 Br 0.1 Crystal photographs; Figure 20 The RbLiCl prepared in Example 12 1.9 I 0.1 Crystal photographs; Figure 21 The RbLiCl prepared in Example 13 1.9 F 0.1 Crystal photographs; Figure 22 Rb prepared in Comparative Example 1 0.9 Cu 0.1 Crystal photograph of LiCl2; Figure 23 Rb prepared in Comparative Example 2 0.4 K 0.6 Crystal photograph of LiCl2; Figure 24 RbLi prepared in Comparative Example 3 0.9 Fe 0.1 Crystal photograph of Cl2; Figure 25 RbLi prepared in Comparative Example 4 0.3 Sr 0.7 Crystal photograph of Cl2; Figure 26 RbLiCl prepared in Comparative Example 5 0.5 I 1.5 Crystal photographs; Figure 27 This is a photograph of the crystal prepared in Comparative Example 6. Detailed Implementation

[0018] The present invention will be further illustrated by the following embodiments. It should be understood that the following embodiments are for illustrative purposes only and are not intended to limit the present invention.

[0019] First, this invention provides an RbLiCl2-based scintillation material. The general chemical formula of the RbLiCl2-based scintillation material can be Rb... 1-a A a Li 1-b M b Cl 2-c X c Or Rb 1-a A a Li 1-b M b Cl 2-c X c :D x ,in: A may include at least one of Na, K, and Cs; M may include at least one of Na, K, Mg, Ca, Sr, Ba, Zn, Cu, and Ag; X may include at least one of F, Br, and I; 0 ≤ a ≤ 0.5, 0 ≤ b ≤ 0.5, and 0 ≤ c ≤ 1.0. D represents the luminescent ion and may include at least one of Tl, Ce, Pr, and Eu, where x represents the luminescent ion relative to Rb. 1-a A a Li 1-b M b Cl 2-c X c The molar doping ratio of the matrix is ​​0.00001≤x≤0.2.

[0020] It should be noted that in the field of crystal scintillating materials, even slight adjustments to the composition can cause significant changes in material properties. RbLiCl2, as a matrix material, exhibits very limited scintillating performance without the addition of activator ions, and is therefore often easily overlooked during large-scale material screening. Furthermore, RbLiCl2, as a halide, is deliquescent, which creates a natural barrier to its performance evaluation. This type of crystal has never been reported in single-crystal form before. This invention is the first to grow RbLiCl2 single crystals using the Bridgman method and discover its scintillating properties. At the same time, preparing single crystals with good scintillating performance also presents significant technical barriers. In summary, developing RbLiCl2 into a high-performance scintillator requires overcoming the following technical difficulties: (1) single-crystal growth technology; (2) a deliquescent sample performance evaluation platform; (3) a scintillating performance testing platform; (4) complex radiation field testing conditions, etc.

[0021] In the RbLiCl2-based scintillation material provided by this invention, Rb acts as a framework, which can promote increased crystal density and enhanced radiation blocking ability. Choosing Na, K, or Cs at position a allows for regulation of scintillation performance by adjusting the local structure of the crystal. If the value of a > 0.5, it will disrupt the original crystal structure, making it impossible to grow high-quality single crystals.

[0022] In some embodiments, the Li in the scintillation material may include naturally abundant Li, 6 Li enrichment of Li. Among them, the method employed... 6 When enriching raw materials with Li, high-neutron-capture-cross-section nuclides can be directly introduced, thereby achieving neutron conversion and scintillation emission within the same material. Similarly, selecting at least one of Na, K, Mg, Ca, Sr, Ba, Zn, Cu, or Ag at the M-site can regulate the local crystal structure, thus controlling the scintillation performance of the material. However, if the value of b is greater than 0.5, it will also disrupt the original crystal structure, preventing the growth of high-quality single crystals.

[0023] Furthermore, halogen modulation can alter the band gap, phonon energy, exciton binding, and crystal field environment of the luminescence center, thereby regulating the emission peak position, decay time, and degree of self-absorption. Using Cl as the matrix halogen element endows RbLiCl2 with fast neutron detection capabilities. Through solid solution treatment with F, Br, and I, the crystal band gap can be modulated, thus controlling the crystal's emission band and scintillation efficiency. However, a c value greater than 1 will disrupt the original crystal structure, leading to difficulties in crystal growth.

[0024] For Tl + Isovalent luminescent ions can preferentially replace Rb in matrix materials. + The site forms a Tl-bound or associated localized luminescent center. In some embodiments, the luminescent ion D is Tl. + And replace Rb + The site is preferably 0.001 ≤ x ≤ 0.1, more preferably 0.01 ≤ x ≤ 0.03; the luminescent ion D is Ce. 3+ And replace Rb + The site is preferably 0.01 ≤ x ≤ 0.05; the luminescent ion D is Pr 3+ And replace Rb + The preferred sites are 0.005 ≤ x ≤ 0.03; the luminescent ion D is Eu. 2+ And replace Rb + The preferred site is 0.01 ≤ x ≤ 0.05.

[0025] It should be noted that for Ce 3+ Pr 3+Trivalent ions can be introduced through Rb sites, Li sites, interstitial sites, or defect complexes, and can be compensated for by vacancies, alkali metals, alkaline earth metals, or halide ions. Among them, Ce... 3+ It can provide 5d-4f fast emission centers, suitable for increasing the proportion of fast components and improving time-resolved performance, by adjusting Ce. 3+ Concentration and charge compensation methods can alter electron-hole pairing on Ce. 3+ The efficiency of center transfer, thereby optimizing gamma response and PSD performance; Pr 3+ Doping can generate 4f5d-4f or 4f-4f correlated luminescence, and the pulse shape can be adjusted through its different attenuation channels. For Eu 2+ Divalent ions can achieve stable luminescence through co-doping with alkaline earth metals, halogen regulation, or control by reducing atmosphere.

[0026] In other words, the scintillation material provided by this invention has at least two distinguishable decay components or attenuation groups, namely a fast decay component and a slow decay component (for example, a 100ns component with a decay time accounting for 30% and an 800ns component with a decay time accounting for 70%, which together constitute the decay curve). By replacing or co-doping with ions such as Tl, Ce, Pr, and Eu, the ratio of fast and slow decay components, carrier trapping cross section, defect recombination path, and self-absorption intensity can be adjusted, providing material design space for subsequent optimization of energy resolution, light yield, and PSD performance. Moreover, compared with traditional single-luminescent-center halides, this invention constructs a multi-luminescent-ion selectable system using RbLiCl2 as a matrix, which can adjust the emission wavelength in the ultraviolet, near-ultraviolet, and visible light regions according to application requirements, making it easy to match with photomultiplier tubes, silicon photomultipliers, or ultraviolet-enhanced detectors.

[0027] Furthermore, the RbLiCl2-based scintillation material has a main lattice composed of Rb, Li, and Cl in a stoichiometric ratio of 1:1:2. In its general chemical formula, A represents an alkali metal ion or heavy metal ion that can partially substitute Rb sites, preferably including at least one of Na, K, and Cs; M represents a light element ion or valence-compensating ion that can partially substitute Li sites, preferably including at least one of Na, K, Mg, Ca, Sr, Ba, Zn, Cu, and Ag; X represents a halide ion that can partially substitute Cl sites, preferably including at least one of F, Br, and I; and D represents a luminescent activation ion, preferably including ns. 2 At least one of type luminescent ions and rare earth luminescent ions, wherein ns 2 The luminescent ions include at least one of Tl, In, Sb, Bi, Pb, and Sn, and the rare earth luminescent ions include at least one of Ce, Pr, Eu, Sm, Tb, and Dy.

[0028] In this invention, the 1:1:2 stoichiometric ratio of the RbLiCl2 matrix differs from that of traditional A2BLiX6 or A2LiMX6 type 2:1:6 or other stoichiometric ratio halide scintillators. Traditional 2:1:6 halides typically form a complex double perovskite or cryolite-type three-dimensional framework with six-coordinate [MX6] polyhedra and LiX6 polyhedra. Their luminescence process often depends on the energy transfer matching between rare earth ions and intrinsic core-to-valence luminescence, valence band-conduction band transitions, or self-trapped excitons. However, the RbLiCl2 matrix of this invention is a simple ternary stoichiometric halide system of Rb-Li-Cl, which does not contain trivalent rare earth matrix cations such as Y, La, and Gd. Its lattice composition is simpler, the cation valence is lower, and Li and Rb respectively assume different radiative response functions in the lattice. Li element, especially... 6 Li isotopes can be passed through 6 The Li(n,α)t nuclear reaction produces alpha particles and tritium nuclei, thus forming a light element neutron conversion center; Rb, with its high atomic number, enhances photoelectric absorption and Compton scattering response to X-rays and gamma rays, thus forming a heavy element gamma response center. Therefore, this invention simultaneously constructs light element neutron conversion centers and heavy element gamma response centers in the same 1:1:2 matrix, providing the material with a structural basis for detecting X-rays, gamma rays, alpha particles, and neutron multimode radiation.

[0029] In the aforementioned RbLiCl2 matrix, the introduction of different luminescent ions can modulate carrier trapping, exciton localization, radiative recombination, emission wavelength, and decay kinetics. Specifically, Tl, In, and other ns 2 Type ions have s 2 The ground-state electronic configuration typically emits light from nanoseconds (ns). 2 →ns 1 np 1 Related transitions, with large absorption cross sections and strong lattice coupling capabilities, can effectively trap electron-hole pairs or self-trapped excitons generated by ionizing radiation, forming broadband emission centers. Rare earth ions such as Ce and Pr have permissible 5d-4f transitions, providing faster luminescence decay components, which is beneficial for achieving fast time response. Eu can generate efficient visible luminescence through 5d-4f transitions. By selecting different luminescent ions and their doping concentration x, the positions of the excited state energy levels relative to the conduction band, valence band, and self-trapped exciton energy levels of the RbLiCl2 matrix can be adjusted, thereby changing the carrier trapping probability to the luminescence center, the nonradiative recombination probability, and the ratio of fast and slow decay components, achieving comprehensive control over emission wavelength, luminescence intensity, decay time, and energy resolution.

[0030] Furthermore, by controlling the luminescent ion doping concentration x, the Rb site substitution ratio a, the Li site substitution ratio b, and the halogen site substitution ratio c, this invention can adjust the local coordination environment and band gap structure of the crystal while maintaining the RbLiCl2 main phase structure. When x is too low, the carriers generated by ionizing radiation are difficult to be captured by the luminescent centers in time, leading to an increase in intrinsic defect capture and non-radiative losses; when x is too high, the distance between the luminescent centers is too close, which easily leads to concentration quenching, energy migration quenching, or enhanced self-absorption. Therefore, this invention preferably controls the luminescent ion doping concentration within the range of 0.005 ≤ x ≤ 0.05 to balance carrier capture efficiency and concentration quenching suppression. By partially substituting Cl with F, Br, or I, the contribution of halogen p orbitals to the valence band top can be adjusted, thereby changing the band gap width, exciton binding energy, and the degree of localization of self-trapped excitons. By partially substituting Rb sites with K, Cs, Tl, In, etc., the lattice distortion and local crystal field intensity around the luminescence center can be changed, thereby controlling the emission peak position, Stokes shift, and decay dynamics. By partially substituting Li sites with Na, Mg, Ca, etc., the spatial distribution of Li-related defects, vacancy compensation, and neutron conversion centers can be adjusted, thereby improving the uniformity of neutron response and pulse shape discrimination capability.

[0031] The PSD performance of the RbLiCl2-based scintillation material described in this invention originates from the differences in ionization density generated by different radiating particles in the crystal and the resulting differences in carrier recombination paths. Gamma rays or X-rays mainly generate low linear energy transfer density electronic events through processes such as the photoelectric effect and Compton scattering, where carriers easily migrate to the luminescent ion center and form relatively fast radiative recombination. Alpha particles, tritium nuclei, or neutron capture reaction products have higher linear energy transfer densities, easily inducing stronger exciton localization, self-trapped exciton formation, and defect-related slow component luminescence. By selecting different luminescent ions such as Tl, In, Ce, Pr, Eu, and Sm, the ratio of fast to slow luminescence channels can be adjusted, resulting in distinguishable differences in pulse decay curves under different particle excitations, thereby achieving pulse shape discrimination for α / γ, neutron / γ, or X / γ events. In particular, when ns 2 When luminescent centers and rare-earth luminescent centers coexist, broadband self-trapped exciton coupled luminescence and fast 5d-4f luminescence channels can be introduced simultaneously, resulting in significant differences in the pulse leading-edge, tail-end integral ratio, and attenuation constant, thereby further improving the PSD discrimination capability.

[0032] Therefore, the essential differences between this invention and existing 2:1:6 type lithium halide scintillators include at least the following aspects: First, the matrix stoichiometry is different: this invention uses a ternary halide system of Rb:Li:Cl=1:1:2, rather than a complex 2:1:6 halide system of A2LiMX6 or A2BLiX6; Second, the lattice cation composition is different: this invention does not rely on trivalent matrix cations such as Y, La, and Gd to construct the luminescent framework, but instead uses Rb, Li, and Cl to form a simple matrix, and forms a tunable activation center by adding external luminescent ions; Third, the construction method of the radiation response center is different: this invention uses Li to form a light element neutron conversion center, and Rb to form a heavy element γ response center, achieving neutron and γ response functional coupling in a simple 1:1:2 matrix; Fourth, the luminescence regulation mechanism is different: traditional 2:1:6 type halides mostly rely on energy transfer between rare earth ions such as Ce and Pr and the intrinsic luminescence of the matrix, while this invention can achieve luminescence regulation through ns 2 Fifth, the PSD regulation mechanism differs: This invention achieves regulation of α / γ and neutron / γ pulse shape discrimination through the coupling of Li-related high LET reaction products, Rb-related γ response, and fast and slow decay channels of the doped luminescent centers in a 1:1:2 matrix, rather than simply using the existing CVL or rare-earth luminescence mechanism in 2:1:6 halides. Therefore, this invention differs from existing 2:1:6 isohalide scintillation materials in terms of matrix composition, lattice structure, luminescent center construction, radiation response path, and PSD regulation mechanism. This is achieved by using type ions, rare-earth ions, and their co-doping methods to modulate the competitive relationship between self-trapped exciton trapping, carrier recombination, 5d-4f luminescence, 4f-4f luminescence, and broadband sp luminescence.

[0033] Therefore, this invention, through the synergistic effect of a 1:1:2 matrix design of RbLiCl2, a neutron conversion center of the light element Li, a γ-response center of the heavy element Rb, and the doping and modulation of multiple types of luminescent ions, can achieve a unified construction of responses to X-rays, γ-rays, α-particles, and neutron radiation. This material system not only achieves ionizing radiation luminescence response, but also allows for controllable optimization of emission wavelength, decay kinetics, light output, energy resolution, and PSD performance through adjustment of the type of luminescent ions, doping concentration, and halogen / cation sites. This ensures its application potential in fields such as nuclear radiation detection, nuclear material identification, neutron-γ dual-mode detection, space radiation monitoring, security inspection, and high-energy physics experiments.

[0034] In some embodiments, the morphology of the RbLiCl2-based scintillation material may include bulk single crystals, polycrystalline ceramics, thin films, microcrystalline powders, or composite screens, preferably containing... 6Bulk single crystals enriched in Li; wherein, the bulk single crystal RbLiCl2-based scintillation material belongs to the orthorhombic crystal system, space group Cmcm. Furthermore, the specific cell parameters can be obtained through analysis of the crystal structure. Variations in cell parameters are caused by differences in composition. Specifically, if the cell sizes in directions a, b, and c differ significantly, stress concentration may occur during crystal growth, leading to increased scintillation cracking. On the other hand, changes in cell parameters reflect changes in crystal structure, which in turn affects scintillation performance.

[0035] In some embodiments, the RbLiCl2-based scintillation material in 241 The PSD quality factor FoM in the test of Am source or mixed radiation field containing alpha particles and gamma rays can be ≥0.8, preferably ≥1.0, more preferably ≥1.3; it can produce ultraviolet, near-ultraviolet or visible light emission under X-ray, gamma-ray, alpha particle or neutron excitation with emission peaks located at 250-750 nm and average decay time of 300-400 ns.

[0036] As examples, RbLiCl2:Tl scintillation materials exhibit an emission peak around 302 nm under photo-induced or ionizing radiation excitation and produce the same emission peak under excitation around 250 nm, exhibiting pulse shape differences suitable for α / γ or n / γ event discrimination. Furthermore, RbLiCl2:Tl scintillation materials have an average decay time of approximately 366 ns and a PSD quality factor of approximately 1.3. RbLiCl2:Ce scintillation materials exhibit an emission peak around 380 nm under photo-induced or ionizing radiation excitation and produce the same emission peak under excitation around 250 nm, matching the PMT-sensitive wavelength and suitable for radiation detection. RbLiCl2:Pr scintillation materials exhibit emission peaks around 350 nm and 375 nm under photo-induced or ionizing radiation excitation and produce the same emission peak under excitation around 250 nm, matching the PMT-sensitive wavelength and suitable for radiation detection. RbLiCl2:Eu scintillation materials exhibit emission peaks around 403 nm and 455 nm under photo-induced or ionizing radiation excitation. The strong emission peak near nm and the emission peak generated under excitation near 250 nm have the characteristic strong emission of Pr and have strong radiation detection potential.

[0037] The following is an exemplary description of a method for preparing the RbLiCl2-based scintillation material. The preparation method may include the following steps: weighing and mixing raw materials according to the stoichiometric ratio of the chemical composition of the RbLiCl2-based scintillation material in an anhydrous and oxygen-free environment; then placing the mixed raw materials in a quartz ampoule or crucible for impurity removal; and finally, performing crystal growth using the Bridgman method, crucible lowering method, temperature gradient method, or micro-pull-down method to obtain the RbLiCl2-based scintillation material.

[0038] In some embodiments, the raw material may include at least one of RbCl, LiCl, TlCl, CeCl3, PrCl3, and EuCl2, and the purity may be ≥99.9%, preferably ≥99.99%.

[0039] In some embodiments, the inner wall of the quartz ampoule or crucible may be coated with a carbon film or boron nitride coating. This prevents the melt formed after the raw material is heated from reacting directly with the quartz wall and reduces heterogeneous nucleation.

[0040] In some embodiments, the process for removing impurities from the raw materials can be heat treatment under a vacuum environment; preferably, the vacuum degree of the vacuum environment can be ≤1×10⁻⁶. -3 Pa, the heating temperature can be 200-350℃, and the holding time can be 2-48h.

[0041] In some implementations, the Bridgman process may include the following steps: (1) Place the purified raw material powder in a quartz ampoule or crucible with a 1-2 cm capillary structure, evacuate and seal it; (2) Transfer the sealed quartz ampoule or crucible to the crucible rack and let it stand for 1-2 hours, and use an electric spark gun vacuum detector to check the crucible's sealing performance; (3) Place the quartz ampoule or crucible after vacuum testing vertically in the crystal growth furnace, then heat it to the highest raw material melting temperature and keep it at that temperature so that the raw material powder is completely melted and fully mixed. (4) Adjust the height and position of the quartz ampoule or crucible and the furnace temperature so that the temperature of the capillary tip of the quartz crucible is maintained within ±10℃ of the crystallization point of the RbLiCl2-based scintillation material; (5) Adjust the longitudinal temperature gradient of the crystal growth furnace and lower the quartz ampoule or crucible inside the furnace to start crystal growth; (6) After growth is completed, the temperature is lowered to room temperature to obtain the RbLiCl2-based scintillation material.

[0042] In step (3), the maximum melting temperature of the raw material can be 550-850℃, preferably 550-750℃; the holding time can be 2-48 h.

[0043] In step (5), the longitudinal temperature gradient of the crystal growth furnace can be 5-50℃ / cm, and the descent speed of the quartz ampoule or crucible within the furnace can be 0.01-10.0 mm / h, preferably 0.05-2 mm / h. An excessively large temperature gradient can lead to crystal growth cracking; an excessively small temperature gradient can cause the grown crystal to become cloudy and contain inclusions. A descent speed that is too fast can cause crystal cracking and inclusions; a descent speed that is too slow can increase costs.

[0044] In step (6), the rate of cooling to room temperature can be 0.5-50℃ / h, preferably 0.5-30℃ / h. If the cooling rate is too fast, the thermal stress of crystal growth will not be released in time, causing crystal cracking; if the cooling rate is too slow, the growth cost will increase.

[0045] In summary, the RbLiCl2-based scintillation material prepared by the method provided in this invention contains at least two distinguishable attenuation components, possessing the advantages of lithium neutron trapping ability, high halide luminescence efficiency, and tunable energy levels of multiple luminescent ions. Furthermore, by introducing luminescent ions such as Tl, Ce, Pr, and Eu into the RbLiCl2 matrix, it can form ultraviolet, near-ultraviolet, or visible light emission, making it suitable for use with thermal neutrons (especially those containing...). 6 The system can detect Li thermal neutrons, fast neutrons, alpha particles, gamma rays, X-rays, alpha / gamma mixed radiation fields, neutron / gamma mixed radiation fields, weak gamma field counting, etc., and can distinguish alpha events, gamma events and / or neutron events based on pulse shape differences. Moreover, it can also be applied to nuclear material identification, reactor monitoring, homeland security inspection, space radiation monitoring, oil well logging or medical imaging.

[0046] Furthermore, the RbLiCl2-based scintillation material provided by this invention can also be used to fabricate single-pixel detectors, array detectors, portable nuclide identifiers, thermal neutron counters, alpha contamination monitors, X-ray imaging screens, gamma spectrometers, or mixed radiation field discrimination detectors. Moreover, optimization can be achieved by selecting different luminescent ions and isotope abundances, balancing high light yield, fast response, PSD capability, and detector matching.

[0047] As an example, when using 6 When Li enriches the RbLiCl2 matrix, the material can be directly utilized. 6 The Li(n,α)t reaction enables thermal neutron detection; when using systems with significant slow components or defect coupling luminescence, such as Tl and Eu, the neutron / γ or α / γ pulse shape difference can be further enhanced; when using fast luminescent centers such as Ce or Pr, it can be used to improve the count rate and time resolution.

[0048] The following examples further illustrate the present invention in detail. It should also be understood that the following examples are only for further explanation of the present invention and should not be construed as limiting the scope of protection of the present invention. Any non-essential improvements and adjustments made by those skilled in the art based on the above description of the present invention are within the scope of protection of the present invention. The specific process parameters, etc., in the following examples are merely examples within a suitable range; that is, those skilled in the art can make appropriate selections within the range based on the description herein, and are not intended to be limited to the specific values ​​in the examples below. Unless otherwise specified, the technical means used in the examples are conventional means well known to those skilled in the art.

[0049] Unless otherwise specified, all RbCl, LiCl and doped ion halides used are anhydrous high-purity raw materials, preferably with a purity of not less than 99.9%, and more preferably not less than 99.99%. Weighing, mixing, tube loading and transfer processes are preferably carried out in an inert atmosphere glove box with a water and oxygen content of less than 1 ppm.

[0050] Unless otherwise specified, the performance testing method is as follows: (1) Photoluminescence test: Xenon lamp or deuterium lamp is used as excitation source to record excitation spectrum and emission spectrum. For RbLiCl2:Tl sample, it is preferred to monitor emission near 302 nm and scan excitation spectrum, or use excitation near 250 nm to record emission spectrum; (2) Ionizing radiation luminescence test: The sample is excited by an X-ray tube, a γ source or an α source, and the emission spectrum is collected by a spectrometer to confirm the consistency between the scintillation emission peak position and the photoluminescence peak position; (3) Pulse height spectrum test: The sample is coupled with a photomultiplier tube or silicon photomultiplier, and the following is used: 241 Am、 137 Tests were conducted using Cs or neutron sources to obtain ADC spectra, energy resolution, light yield, or relative light output. (4) Attenuation and PSD test: Record the waveform of a single event and define the PSD ratio as the ratio of the slow integration window charge to the total integration window charge, or as the ratio of the tail integration to the full integration. Calculate FoM based on the distribution of the PSD ratio of α, γ or neutron events, FoM=(μ1-μ2) / (FWHM1+FWHM2).

[0051] Example 1 The preparation method of RbLiCl2-based scintillation material RbLiCl2:Tl provided in this embodiment includes the following steps: Press Rb 0.99 LiCl2:Tl 0.01 High-purity raw materials RbCl, LiCl, and TlCl, with a purity of 99.9% and a total mass of 5g, were weighed according to their chemical composition elemental ratio, thoroughly ground and mixed, and then packed into a carbon-film quartz ampoule. Next, in a glove box filled with argon or nitrogen, the raw materials were mixed evenly and transferred into a quartz crucible with a 2 cm long capillary bottom. The crucible was then evacuated to a vacuum of 1 × 10⁻⁶. -3 After Pa, the temperature is raised to 200℃ and held for 24 hours to further remove residual adsorbed impurities. Then, the product is soldered and sealed. The sealed quartz crucible was transferred to a crucible rack and left to stand. The crucible's airtightness was then checked using an electric spark gun vacuum detector. The encapsulated quartz crucible was placed in a vertical crystal growth furnace and heated to 850℃ for melting and homogenization, and held at that temperature for 12 hours. Then, the temperature was lowered to 600℃, so that the temperature of the capillary tip of the quartz crucible was maintained at 350℃. The longitudinal temperature gradient of the crystal growth furnace was adjusted to 25℃ / cm, and directional solidification and crystal growth were carried out at a lowering rate of 1 mm / h. After the crystal growth was completed, the temperature was lowered to room temperature at a rate of 10℃ / h to obtain the RbLiCl2:Tl crystal scintillation material.

[0052] Example 2 The preparation method of the RbLiCl2-based scintillation material RbLiCl2:Tl provided in this embodiment is the same as in Example 1, with the main difference being: Press Rb 0.99999 LiCl2:Tl 0.00001 The chemical composition of the raw material powder is measured by weighing the elements in the specified ratio.

[0053] Example 3 The preparation method of the RbLiCl2-based scintillation material RbLiCl2:Tl provided in this embodiment is the same as in Example 1, with the main difference being: Press Rb 0.8 LiCl2:Tl 0.2 The chemical composition of the raw material powder is measured by the stoichiometric ratio of the elements.

[0054] Example 4 The preparation method of the RbLiCl2-based scintillation material RbLiCl2:Ce provided in this embodiment is the same as in Example 1, with the main difference being: Press Rb 0.99 LiCl2:Ce 0.01 The chemical composition of the raw material powder is measured by weighing the elements in the specified ratio.

[0055] Example 5 The preparation method of the RbLiCl2-based scintillation material RbLiCl2:Pr provided in this embodiment is the same as in Example 1, with the main difference being: Press Rb 0.99 LiCl2:Pr 0.01 The chemical composition of the raw material powder is measured by weighing the elements in the specified ratio.

[0056] Example 6 The preparation method of the RbLiCl2-based scintillation material RbLiCl2:Eu provided in this embodiment is the same as in Example 1, with the main difference being: Press Rb 0.99 LiCl2:Eu 0.01 The chemical composition of the raw material powder is measured by weighing the elements in the specified ratio.

[0057] Example 7 The preparation method of the RbLiCl2-based scintillation material RbLiCl2:Tl / Ce provided in this embodiment is the same as in Example 1, with the main difference being: Press Rb 0.98 LiCl2:Tl 0.01 / Ce 0.01 The chemical composition of the raw material powder is measured by weighing the elements in the specified ratio.

[0058] Example 8 The preparation method of the RbLiCl2-based scintillation material RbLiCl2:Tl / Pr provided in this embodiment is the same as in Example 1, with the main difference being: Press Rb 0.98 LiCl2:Tl 0.01 / Pr 0.01 The chemical composition of the raw material powder is measured by weighing the elements in the specified ratio.

[0059] Example 9 The preparation method of the RbLiCl2-based scintillation material RbLiCl2:Tl / Eu provided in this embodiment is the same as in Example 1, with the main difference being: Press Rb 0.98 LiCl2:Tl 0.01 / Eu 0.01 The chemical composition of the raw material powder is measured by weighing the elements in the specified ratio.

[0060] Example 10 The preparation method of the RbLiCl2-based scintillation material RbLiCl2:Ce / Pr provided in this embodiment is the same as in Example 1, with the main difference being: Press Rb 0.98 LiCl2:Pr 0.01 / Ce 0.01 The chemical composition of the raw material powder is measured by weighing the elements in the specified ratio.

[0061] Example 11 The preparation method of RbLiCl2-based scintillation material RbLi(Cl / Br)2 provided in this embodiment is the same as in Example 1, with the main difference being: According to RbLiCl 1.9 Br 0.1 The chemical composition of the raw material powder is measured by weighing the elements in the specified ratio.

[0062] Example 12 The preparation method of RbLiCl2-based scintillation material RbLi(Cl / I)2 provided in this embodiment is the same as in Example 1, with the main difference being: According to RbLiCl 1.9 I 0.1 The chemical composition of the raw material powder is measured by weighing the elements in the specified ratio.

[0063] Example 13 The preparation method of RbLiCl2-based scintillation material RbLi(Cl / F)2 provided in this embodiment is the same as in Example 1, with the main difference being: According to RbLiCl 1.9 F 0.1 The chemical composition of the raw material powder is measured by weighing the elements in the specified ratio.

[0064] Comparative Example 1 The preparation method of the RbLiCl2-based scintillation material provided in this comparative example is the same as that in Example 1, with the main difference being: Press Rb 0.9 Cu 0.1 Weigh the raw material powder according to the stoichiometric ratio of the chemical constituent elements of LiCl2.

[0065] Comparative Example 2 The preparation method of the RbLiCl2-based scintillation material provided in this comparative example is the same as that in Example 1, with the main difference being: Press Rb 0.4 K 0.6 Weigh the raw material powder according to the stoichiometric ratio of the chemical composition elements of LiCl2.

[0066] Comparative Example 3 The preparation method of the RbLiCl2-based scintillation material provided in this comparative example is the same as that in Example 1, with the main difference being: According to RbLi 0.9 Fe 0.1 The chemical composition of Cl2 is measured by weighing the raw material powder.

[0067] Comparative Example 4 The preparation method of the RbLiCl2-based scintillation material provided in this comparative example is the same as that in Example 1, with the main difference being: According to RbLi 0.3 Sr 0.7 The chemical composition of Cl2 is measured by weighing the raw material powder.

[0068] Comparative Example 5 The preparation method of the RbLiCl2-based scintillation material provided in this comparative example is the same as that in Example 1, with the main difference being: According to RbLiCl 0.5 I 1.5 The chemical composition of the raw material powder is measured by weighing the elements in the specified ratio.

[0069] Comparative Example 6 The preparation method of the RbLiCl2-based scintillation material provided in this comparative example is the same as that in Example 1, with the main difference being: The crucible descends at a speed of 50 mm / h.

[0070] The obtained crystal was cut and polished, and its photoluminescence, ionizing radiation luminescence, pulse height spectrum, decay curve and PSD performance were tested at room temperature.

[0071] Figure 1 The images show crystal blanks and end faces of RbLiCl2-based samples under different luminescent ion doping conditions. As can be seen from the figures, the RbLiCl2-based samples exhibit excellent crystallinity and can be doped with luminescent ions.

[0072] Figure 2 Rb prepared in Example 1 0.99 LiCl2:Tl 0.01 X-ray emission spectrum of the sample. The figure shows that Rb... 0.99 LiCl2:Tl 0.01 A strong emission peak exists at approximately 302 nm.

[0073] Figure 3 Rb prepared in Example 1 0.99 LiCl2:Tl 0.01 Photoluminescence excitation and emission spectra of the sample. As can be seen from the figure, Rb... 0.99 LiCl2:Tl 0.01 Two photoluminescence peaks are present at approximately 304 nm and 395 nm. Both excitation peaks are caused by the excitation peak at 250 nm. The sample exhibits a large Stokes shift, indicating that the sample has a small self-absorption effect.

[0074] Figure 4 Rb prepared in Example 1 0.99 LiCl2:Tl 0.01 Sample in 241 The height spectrum of the mixed alpha and gamma radiation pulse measured under an Am source. As can be seen from the figure, Rb... 0.99 LiCl2:Tl 0.01 An Alpha Gamma response exists.

[0075] Figure 5 Rb prepared in Example 1 0.99 LiCl2:Tl 0.01 Sample in 241 The PSD ratio-ADC two-dimensional distribution plot was tested under an Am source. The plot shows a clear distinction between the alpha and gamma signals, indicating that the crystal can achieve alpha-gamma discrimination.

[0076] Figure 6 Rb prepared in Example 1 0.99 LiCl2:Tl 0.01 Sample in 241The scintillation decay curves and multi-exponential fitting results under an Am source are shown in the figure. As can be seen from the figure, the decay curves of the alpha and gamma signals were obtained by extracting the alpha and gamma signals, averaging and fitting their decay signals. Fitting the decay curves revealed that the alpha signal is a single component, while the gamma signal exhibits a three-component characteristic, indicating a significant difference in the crystal's response to alpha and gamma events. That is, the RbLiCl2:Tl sample can be fitted using a multi-exponential model, where the contribution ratio of the three components is approximately p. γ1 =7.26%, p γ2 =57.36%, p γ3 =35.38%, average decay time t α Approximately 366 ns, this multi-component decay behavior is beneficial for constructing PSD parameters.

[0077] Figure 7 Rb prepared in Example 1 0.99 LiCl2:Tl 0.01 Sample in 241 PSD ratio projection and Gaussian fitting plot under Am source. As can be seen from the figure, the FoM value reaches 1.3, indicating that the crystal can achieve alpha-gamma discrimination. RbLiCl2:Tl can be used as a candidate scintillation material for α / γ discrimination and further neutron / γ discrimination optimization.

[0078] Figure 8 Rb prepared in Example 1 0.99 LiCl2:Tl 0.01 Sample in 241 A comparison of the pulse height spectrum of an Am source after selecting the alpha event with the spectrum of all events. The figure shows that after alpha gamma discrimination, alpha events can be effectively extracted from the gamma background.

[0079] Figure 9 The image shows the X-ray emission spectrum of the RbLiCl2 sample. As can be seen from the image, RbLiCl2 exhibits a weak emission peak at approximately 377 nm.

[0080] Figure 10 Rb prepared in Example 4 0.99 LiCl2:Ce 0.01 X-ray emission spectrum of the sample. The figure shows that Rb... 0.99 LiCl2:Ce 0.01 A weak emission peak exists at approximately 380 nm.

[0081] Figure 11 Rb prepared in Example 5 0.99 LiCl2:Pr 0.01 X-ray emission spectrum of the sample. The figure shows that Rb... 0.99LiCl2:Pr 0.01 Strong emission peaks exist at approximately 350 and 375 nm.

[0082] Figure 12 Rb prepared in Example 6 0.99 LiCl2:Eu 0.01 X-ray emission spectrum of the sample. The figure shows that Rb... 0.99 LiCl2:Eu 0.01 Strong emission peaks exist at 403 and 455 nm.

[0083] Figure 13 Rb prepared in Example 2 0.99999 LiCl2:Tl 0.00001 The image shows a crystal photograph. It can be seen from the image that the single crystal is intact.

[0084] Figure 14 Rb prepared in Example 3 0.8 LiCl2:Tl 0.2 The image shows a crystal photograph. It can be seen from the image that the single crystal is intact.

[0085] Figure 15 Rb prepared in Example 7 0.98 LiCl2:Tl 0.01 / Ce 0.01 The image shows a crystal photograph. It can be seen from the image that the single crystal is intact.

[0086] Figure 16 Rb prepared in Example 8 0.98 LiCl2:Tl 0.01 / Pr 0.01 The image shows a crystal photograph. It can be seen from the image that the single crystal is intact.

[0087] Figure 17 Rb prepared in Example 9 0.98 LiCl2:Tl 0.01 / Eu 0.01 The image shows a crystal photograph. It can be seen from the image that the single crystal is intact.

[0088] Figure 18 Rb prepared in Example 10 0.98 LiCl2:Pr 0.01 / Ce 0.01 A photograph of the crystal. As can be seen from the image, a complete single crystal was obtained.

[0089] Figure 19 The RbLiCl prepared in Example 11 1.9 Br 0.1 A photograph of the crystal. As can be seen from the image, a complete single crystal was obtained.

[0090] Figure 20 The RbLiCl prepared in Example 12 1.9 I 0.1 A photograph of the crystal. As can be seen from the image, a complete single crystal was obtained.

[0091] Figure 21 The RbLiCl prepared in Example 13 1.9 F 0.1 A photograph of the crystal. As can be seen from the image, a complete single crystal was obtained.

[0092] Figure 22 Rb prepared in Comparative Example 1 0.9 Cu 0.1 A photograph of LiCl2 crystals. The image shows a complete single crystal, but the quality is relatively poor.

[0093] Figure 23 Rb prepared in Comparative Example 2 0.4 K 0.6 A photograph of LiCl2 crystals. As can be seen from the image, the crystal quality is relatively poor.

[0094] Figure 24 RbLi prepared in Comparative Example 3 0.9 Fe 0.1 A photograph of Cl2 crystals. The image shows that the crystal quality is relatively poor.

[0095] Figure 25 RbLi prepared in Comparative Example 4 0.3 Sr 0.7 A photograph of Cl2 crystals. The image shows that the crystal quality is relatively poor.

[0096] Figure 26 RbLiCl prepared in Comparative Example 5 0.5 I 1.5 The image shows a photograph of the crystal. It can be seen from the image that the crystal quality is relatively poor.

[0097] Figure 27 This is a photograph of the crystal prepared in Comparative Example 6. As can be seen from the image, the crystal is internally cloudy, making it impossible to obtain a single crystal.

[0098] Although the present invention has been described in detail through the preferred embodiments above, it should be understood that the above description should not be considered as a limitation of the present invention. Various modifications and substitutions to the present invention will be apparent to those skilled in the art after reading the above description. Therefore, the scope of protection of the present invention should be defined by the appended claims.

Claims

1. A RbLiCl2-based scintillation material, characterized in that, The chemical composition of the RbLiCl2-based scintillation material is Rb 0.99 LiCl2:Tl 0.01 Where: the luminescent ion is Tl, and 0.01 indicates that the luminescent ion Tl is relative to Rb. 0.99 Molar doping ratio of the LiCl2 matrix; The RbLiCl2-based scintillation material is a bulk single crystal, belonging to the orthorhombic crystal system and space group Cmcm.

2. The RbLiCl2-based scintillation material according to claim 1, characterized in that, The Li in the RbLiCl2-based scintillation material is naturally abundant Li or... 6 Li enriched in Li.

3. A method for preparing the RbLiCl2-based scintillation material according to claim 1, characterized in that, The preparation method includes the following steps: weighing and mixing raw materials according to the stoichiometric ratio of the chemical composition elements of the RbLiCl2-based scintillation material as described in claim 1 in an anhydrous and oxygen-free environment; then placing the mixed raw materials in a quartz ampoule or crucible to remove impurities; and then growing crystals by the Bridgman method, crucible lowering method, temperature gradient method or micro-pull-down method to obtain the RbLiCl2-based scintillation material.

4. The preparation method according to claim 3, characterized in that, The Bridgeman process The process includes the following steps: placing the raw material powder in a quartz ampoule or crucible and evacuating and sealing it, then placing it in a crystal growth furnace, heating it to the highest raw material melting temperature and holding it at that temperature; next, adjusting the height and position of the quartz ampoule or crucible, the furnace temperature, and the longitudinal temperature gradient of the crystal growth furnace, and lowering the quartz ampoule or crucible inside the furnace to begin crystal growth; after growth is completed, cooling to room temperature to obtain the RbLiCl2-based scintillation material.

5. The preparation method according to claim 4, characterized in that, The maximum melting temperature of the raw materials is 550-850℃, and the holding time is 2-48 h.

6. The preparation method according to claim 4, characterized in that, The longitudinal temperature gradient of the crystal growth furnace is 5-50℃ / cm, and the quartz ampoule or crucible descends at a rate of 0.01-10.0 mm / h within the furnace.

7. The preparation method according to claim 4, characterized in that, The rate of cooling to room temperature is 0.5-50℃ / h.

8. The application of the RbLiCl2-based scintillation material according to claim 1 in nuclear radiation detection, characterized in that, The nuclear radiation detection includes neutron detection, alpha particle detection, gamma ray detection, X-ray imaging, alpha / gamma discrimination, neutron / gamma discrimination, nuclear material identification, reactor monitoring, homeland security inspection, space radiation monitoring, oil well logging, and medical imaging.

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