LI+ DOPED METAL HALIDE SCINTILLATION CRYSTAL WITH ZERO-DIMENSIONAL PEROVSKITE STRUCTURE, PREPARATION METHOD AND USE THEREOF

Abstract

Disclosed are a Li.sup.+ doped metal halide scintillation crystal with a zero-dimensional perovskite structure, a preparation method and use thereof. The scintillation crystal has a chemical formula of Cs.sub.3-xCu.sub.2I.sub.5:xLi, where x is in a range of 0.003 to 0.3. The method for preparing the scintillation crystal comprises the steps of: weighting and fully mixing a CuI powder, a CsI powder and a LiI powder in a molar ratio of 2:(3-x):x in an inert atmosphere to obtain a mixed powder, and growing into the scintillation crystal from the mixed powder by Bridgman Stockbarger method. After excited, the scintillation crystal could emit a broadband blue light in a range of 350-550 nm, with an intensity much higher than that of the original pure component crystal. The existence of Li.sup.+ further expands the application of the scintillation crystals from X/γ-ray detection to neutron detection.

Claims

1. A Li.sup.+ doped metal halide scintillation crystal with a zero-dimensional perovskite structure, which has a chemical formula of Cs.sub.3-xCu.sub.2I.sub.5:xLi.

2. The Li.sup.+ doped metal halide scintillation crystal with a zero-dimensional perovskite structure of claim 1, wherein x is in a range of 0.003 to 0.3.

3. The Li.sup.+ doped metal halide scintillation crystal with a zero-dimensional perovskite structure of claim 1, wherein the scintillation crystal emits a broadband blue light in a range of 350-550 nm when excited by high-energy rays or high-energy particles.

4. The Li.sup.+ doped metal halide scintillation crystal with a zero-dimensional perovskite structure of claim 1, wherein the scintillation crystal identifies neutrons and γ-rays under a co-irradiation of neutrons and γ-rays.

5. A method for preparing a Li.sup.+ doped metal halide scintillation crystal with a zero-dimensional perovskite structure, comprising the steps of: mixing a CuI powder, a CsI powder and a LiI powder in an inert atmosphere to obtain a mixed powder, and adding the mixed powder to a spontaneous nucleation quartz crucible, then sealing the crucible under vacuum, heating and melting the mixed powder, and growing the mixed powder into the scintillation crystal; wherein the scintillation crystal has a chemical formula of Cs.sub.3-xCu.sub.2I.sub.5:xLi.

6. The method of claim 5, wherein the CuI powder, the CsI powder and the LiI powder are weighted in a molar ratio of 2:(3-x):x, and fully mixed to obtain the mixed powder, wherein x is in a range of 0.003 to 0.3; and the scintillation crystal is grown from the mixed powder by Bridgman Stockbarger method.

7. A method of using the Li.sup.+ doped metal halide scintillation crystal with a zero-dimensional perovskite structure of claim 1, comprising using the Li.sup.+ doped metal halide scintillation crystal in the detection of X-ray, γ-ray or neutron.

8. The Li.sup.+ doped metal halide scintillation crystal with a zero-dimensional perovskite structure of claim 2, wherein the scintillation crystal emits a broadband blue light in a range of 350-550 nm when excited by high-energy rays or high-energy particles.

9. The Li.sup.+ doped metal halide scintillation crystal with a zero-dimensional perovskite structure of claim 2, wherein the scintillation crystal identifies neutron and γ-ray under a co-irradiation of neutron and γ-ray.

10. The Li.sup.+ doped metal halide scintillation crystal with a zero-dimensional perovskite structure of claim 3, wherein the scintillation crystal identifies neutron and γ-ray under a co-irradiation of neutron and γ-ray.

11. The method of claim 5, wherein x is in a range of 0.003 to 0.3.

12. The method of claim 5, wherein the scintillation crystal emits a broadband blue light in a range of 350-550 nm when excited by high-energy rays or high-energy particles.

13. The method of claim 11, wherein the scintillation crystal emits a broadband blue light in a range of 350-550 nm when excited by high-energy rays or high-energy particles.

14. The method of claim 5, wherein the scintillation crystal identifies neutron and γ-ray under a co-irradiation of neutron and γ-ray.

15. The method of claim 11, wherein the scintillation crystal identifies neutron and γ-ray under a co-irradiation of neutron and γ-ray.

16. The method of claim 12, wherein the scintillation crystal identifies neutron and γ-ray under a co-irradiation of neutron and γ-ray.

17. The method of claim 11, wherein the CuI powder, the CsI powder and the LiI powder are weighted in a molar ratio of 2:(3-x):x, and fully mixed to obtain the mixed powder, wherein x is in a range of 0.003 to 0.3; and the scintillation crystal is grown from the mixed powder by Bridgman Stockbarger method.

18. The method of claim 12, wherein the CuI powder, the CsI powder and the LiI powder are weighted in a molar ratio of 2:(3-x):x, and fully mixed to obtain the mixed powder, wherein x is in a range of 0.003 to 0.3; and the scintillation crystal is grown from the mixed powder by Bridgman Stockbarger method.

19. The method of claim 14, wherein the CuI powder, the CsI powder and the LiI powder are weighted in a molar ratio of 2:(3-x):x, and fully mixed to obtain the mixed powder, wherein x is in a range of 0.003 to 0.3; and the scintillation crystal is grown from the mixed powder by Bridgman Stockbarger method.

20. A method of using the Li.sup.+ doped metal halide scintillation crystal with a zero-dimensional perovskite structure of claim 2, comprising using the Li.sup.+ doped metal halide scintillation crystal in the detection of X-ray, γ-ray or neutron.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0008] FIG. 1 shows photographs of real objects of the LF doped metal halide scintillation crystals with a zero-dimensional perovskite structure according to Examples 1-5.

[0009] FIG. 2 shows the X-ray diffraction pattern of Cs.sub.2.85Cu.sub.2I.sub.5:5% Li scintillation crystal according to Example 1.

[0010] FIG. 3 shows the fluorescence spectra of Cs.sub.2.85Cu.sub.2I.sub.5:5% Li scintillation crystal according to Example 1, Cs.sub.2.997Cu.sub.2I.sub.5:0.1% Li scintillation crystal according to Example 2, Cs.sub.2.91 Cu.sub.2I.sub.5:3% Li scintillation crystal according to Example 4, and Cs.sub.2.7 Cu.sub.2I.sub.5:10% Li scintillation crystal according to Example 5.

[0011] FIG. 4 shows the X-ray excitation emission spectra of Cs.sub.2.85 Cu.sub.2I.sub.5:5% Li scintillation crystal according to Example 1, Cs.sub.2.997Cu.sub.2I.sub.5:0.1% Li scintillation crystal according to Example 2, Cs.sub.2.97 Cu.sub.2I.sub.5:1% Li scintillation crystal according to Example 3, and Cs.sub.2.7 Cu.sub.2I.sub.5:10% Li scintillation crystal according to Example 5.

[0012] FIG. 5 shows the decay time of the Cs.sub.2.85 Cu.sub.2I.sub.5:5% Li scintillation crystal according to Example 1.

[0013] FIG. 6 is a diagram showing transmittance of the Cs.sub.2.85 Cu.sub.2I.sub.5:5% Li scintillation crystal according to Example 1 and the Cs.sub.2.997Cu.sub.2I.sub.5:0.1% Li scintillation crystal according to Example 2.

DETAILED DESCRIPTION OF THE EMBODIMENTS

[0014] The present disclosure will be further described below in conjunction with the drawings and examples. It should be understood that the drawings and examples are only intended to illustrate, not to limit the present disclosure.

[0015] In the present disclosure, a new scintillation crystal material that meets the use requirements of high-performance energy spectroscopies and imaging detectors is developed by studying the Cs.sub.3-xCu.sub.2I.sub.5:xLi metal halide scintillation crystal with a zero-dimensional perovskite structure. In the present disclosure, Cs.sub.3-xCu.sub.2I.sub.5:xLi metal halide scintillation crystal with a zero-dimensional perovskite structure is prepared using the CsI powder, the CuI powder and the LiI powder as raw materials, wherein x is in a range of larger than 0.003 to less than or equal to 0.3, based on the characteristic found in practice that Li.sup.+ could improve luminous intensity without changing the ranges of excitation light and emission light of the original pure component crystal.

[0016] Preparation:

[0017] Crucible cleaning: the quartz crucible is ultrasonically cleaned with a low-concentration nitric acid, deionized water and an alcohol in sequence with a liquid level of slightly higher than the main diameter of the crucible, for 20-30 min each time. After cleaning, the crucible is wiped to remove water on the surface thereof, dried in a drying oven overnight, and then placed in a glove box for 2-3 days in advance to ensure that the inner wall of the crucible is free of water when being charged.

[0018] Batching of raw materials: in a glove box with an inert atmosphere, the CuI powder, the CsI powder and the LiI powder are weighted based on a molar ratio of 2:(3-x):x, wherein x is in a range of 0.003 to 0.3, and fully mixed to obtain a mixed powder; then the mixed powder is added to a spontaneous nucleation quartz crucible, and the crucible is sealed under vacuum. In some embodiments, the mixed powder has a high purity, for example, a purity of 99.99% or more, preferably 99.999% or more.

[0019] Crystal growth: the crystal is grown by the Bridgman Stockbarger method under conditions of a vacuum environment, a growth rate controlled at 0.2-1 mm/h, and a temperature in the high temperature zone of a growth furnace of 470-550° C. with a gradient of 15-35° C./mm.

[0020] The present disclosure is further illustrated by the following examples. It should be understood that the following examples are only used to better illustrate the present disclosure, and should not be construed as limiting the protection scope of the present disclosure. Similar adjustments and optimizations made by those skilled in the art according to the above contents of the present disclosure are all within the protection scope of the present disclosure. The experimental methods that do not specify conditions in the following examples are generally performed in accordance with conventional conditions.

[0021] Example 1: Spontaneous nucleation growth of Cs.sub.2.85 Cu.sub.2I.sub.5:5% Li scintillation crystal was performed by Bridgman Stockbarger method:

[0022] (1) In a glove box with an inert atmosphere, 6.4753 g of CuI powder, 12.5878 g of CsI powder and 0.3413 g of LiI powder were weighted based on a stoichiometric ratio of CuI:CsI:LiI of 2:2.85:0.15, and mixed uniformly, obtaining a mixed powder, wherein the CuI powder, the CsI powder and the LiI powder have a purity of 99.99%/a.

[0023] (2) The mixed powder was added to a quartz crucible. After vacuumized, the crucible was sealed by using a flame of a hydrogen-oxygen flame gun to make the quartz column located at the convex part of the narrow wall of the crucible mouth melt with the inner wall, and then placed in a ceramic down pipe. The down pipe was placed on a down mechanism, and the bottom of the crucible was raised to the upper edge of the temperature gradient zone in a descending furnace, and then the temperature was increased.

[0024] (3) The temperature of the high temperature zone of the descending furnace was set to be 470° C., and the mixed powder was heated to a molten state and kept for 30 h.

[0025] (4) The quartz crucible was lowered at a speed of 0.4 mm/h through the down mechanism.

[0026] (5) After the crucible was lowered to a preset distance, the temperature was decreased slowly to room temperature, and then the crucible was taken out and transferred to a glove box. The crystal was taken out by breaking the crucible, cut, ground and polished to be processed into a wafer sample, and the remaining transparent scraps were taken and ground to be processed into a powder sample.

[0027] The obtained crystals are of good quality (see FIG. 1). The X-ray diffraction pattern of the powder sample is closely matched with the standard PDF #44-0077 card for Cs.sub.3Cu.sub.2Is with a good crystallinity (see FIG. 2). When the sample is excited by a 300 nm light source, the self-trapped excitons with an emission center at 446 nm and a range of 350-550 nm are shown to emit light, with a greatly improved emission intensity compared to the pure component crystal (see FIG. 3). The emission spectra under X-ray excitation shows similar results to the fluorescence spectra, indicating an absence of obvious structural defects in the crystals (see FIG. 4). The normal temperature decay time at the monitoring wavelength of 450 nm is 1003 ns (see FIG. 5), which meets the needs of practical radiation detection applications. The wafer sample maintains a good transmittance within the emission band, which is convenient for a photon detector to receive the optical signal (see FIG. 6).

[0028] Example 2: Spontaneous nucleation growth of Cs.sub.2.997Cu.sub.2I.sub.5:0.1% Li scintillation

[0029] crystal was performed by Bridgman Stockbarger method:

[0030] (1) In a glove box with an inert atmosphere, 6.4753 g of CuI powder, 13.2371 g of CsI powder and 0.0068 g of LiI powder were weighted based on a stoichiometric ratio of CuI:CsI:LiI of 2; 2.85; 0.15, and mixed uniformly, obtaining a mixed powder, wherein the CuI powder, the CsI powder and the LiI powder have a purity of 99.99%.

[0031] (2) The mixed powder was added to a spontaneous nucleation quartz crucible. After vacuumized, the crucible was sealed by using a flame of a hydrogen-oxygen flame gun to make the quartz column located at the convex part of the narrow wall of the crucible mouth melt with the inner wall, and then placed in a ceramic down pipe. The down pipe was placed on a down mechanism, and the bottom of the crucible was raised to the upper edge of the temperature gradient zone in a descending furnace, and then the temperature was increased.

[0032] (3) The temperature of the high temperature zone of a descending furnace was set to be 490° C., and the mixed powder was heated to a molten state and kept for 30 h.

[0033] (4) The quartz crucible was lowered at a speed of 1 mm/h through the down mechanism.

[0034] (5) After the crucible was lowered to a preset distance, the temperature was decreased slowly to room temperature, and then the crucible was taken out and transferred to a glove box. The crystal was taken out by breaking the crucible, cut, ground and polished to be processed into a wafer sample, and the remaining transparent scraps were taken and ground to be processed into a powder sample.

[0035] The obtained crystals are of good quality (see FIG. 1). When the sample is excited by a 300 nm light source, the self-trapped excitons with an emission center at 446 nm and a range of 350-550 nm are shown to emit light (see FIG. 3). The emission spectra under X-ray excitation shows similar results to the fluorescence spectra, indicating an absence of obvious structural defects in the crystals (see FIG. 4). The wafer sample maintains a good transmittance within the emission band, which is convenient for a photon detector to receive the optical signal (see FIG. 6).

[0036] Example 3: Spontaneous nucleation growth of Cs.sub.2.97Cu.sub.2I.sub.5:1% Li scintillation crystal was performed by Bridgman Stockbarger method;

[0037] (1) In a glove box with an inert atmosphere, 6.4753 g of CuI powder, 13.1178 g of CsI powder and 0.0683 g of LiI powder were weighted based on a stoichiometric ratio of CuI:CsI:LiI of 2:2.85:0.15, and mixed uniformly, obtaining a mixed powder, wherein the CuI powder, the CsI powder and the LiI powder have a purity of 99.99%.

[0038] (2) The mixed powder was added to a spontaneous nucleation quartz crucible. After vacuumized, the crucible was sealed by using a flame of a hydrogen-oxygen flame gun to make the quartz column located at the convex part of the narrow wall of the crucible mouth melt with the inner wall, and then placed in a ceramic down pipe. The down pipe was placed on a down mechanism, and the bottom of the crucible was raised to the upper edge of the temperature gradient zone in a descending furnace, and then the temperature was increased.

[0039] (3) The temperature of the high temperature zone of the descending furnace was set to be 510° C., and the mixed powder was heated to a molten state and kept for 30 h.

[0040] (4) The quartz crucible was lowered at a speed of 0.8 mm/h through the down mechanism.

[0041] (5) After the crucible was lowered to a preset distance, the temperature was decreased slowly to room temperature, and then the crucible was taken out and transferred to a glove box. The crystal was taken out by breaking the crucible, cut, ground and polished to be processed into a wafer sample, and the remaining transparent scraps were taken and ground to be processed into a powder sample.

[0042] The obtained crystals are of good quality (see FIG. 1). When the sample is excited by a 300 nm light source, the self-trapped excitons with an emission center at 446 nm and a range of 350-550 nm are shown to emit light, with a greatly improved emission intensity compared to the pure component crystal (see FIG. 3). The emission spectra under X-ray excitation shows similar results to the fluorescence spectra, indicating an absence of obvious structural defects in the crystals (see FIG. 4).

[0043] Example 4: Spontaneous nucleation growth of Cs.sub.2.91 Cu.sub.2I.sub.5:3% Li scintillation crystal was performed by Bridgman Stockbarger method:

[0044] (1) In a glove box with an inert atmosphere, 6.4753 g of CuI powder, 12.8528 g of CsI powder and 0.2048 g of LiI powder were weighted based on a stoichiometric ratio of CuI:CsI:LiI of 2:2.85:0.15, and mixed uniformly, obtaining a mixed powder, wherein the CuI powder, the CsI powder and the LiI powder have a purity of 99.99%.

[0045] (2) The mixed powder was added to a spontaneous nucleation quartz crucible. After vacuumized, the crucible was sealed by using a flame of a hydrogen-oxygen flame gun to make the quartz column located at the convex part of the narrow wall of the crucible mouth melt with the inner wall, then placed in a ceramic down pipe. The down pipe was placed on a down mechanism, and the bottom of the crucible was raised to the upper edge of the temperature gradient zone in a descending furnace, and then the temperature was increased.

[0046] (3) The temperature of the high temperature zone of the descending furnace was set to be 530° C., and the mixed powder was heated to a molten state and kept for 30 h.

[0047] (4) The quartz crucible was lowered at a speed of 0.6 mm/h through the down mechanism.

[0048] (5) After the crucible was lowered to a preset distance, the temperature was decreased slowly to room temperature, and then the crucible was taken out and transferred to a glove box. The crystal was taken out by breaking the crucible, cut, ground and polished to be processed into a wafer sample, and the remaining transparent scraps were taken and ground to be processed into a powder sample.

[0049] The obtained crystals are of good quality (see FIG. 1). When the sample is excited by a 300 nm light source, the self-trapped excitons with an emission center at 446 nm and a range of 350-550 nm are shown to emit light, with a greatly improved emission intensity compared to the pure component crystal (see FIG. 3). The emission spectra under X-ray excitation shows similar results to the fluorescence spectra, indicating an absence of obvious structural defects in the crystals (see FIG. 4).

[0050] Example 5: Spontaneous nucleation growth of Cs.sub.2.7 Cu.sub.2I.sub.5:10% Li scintillation crystal was performed by Bridgman Stockbarger method:

[0051] (1) In a glove box with an inert atmosphere, 6.4753 g of CuI powder, 11.9253 g of CsI powder and 0.6826 g of LiI powder were weighted based on a stoichiometric ratio of CuI:CsI:LiI of 2:2.85:0.15, and mixed uniformly, obtaining a mixed powder, wherein the CuI powder, the CsI powder and the LiI powder have a purity of 99.99%.

[0052] (2) The mixed powder was added to a spontaneous nucleation quartz crucible. After vacuumized, the crucible was sealed by using a flame of a hydrogen-oxygen flame gun to make the quartz column located at the convex part of the narrow wall of the crucible mouth melt with the inner wall, then placed in a ceramic down pipe. The down pipe was placed on a down mechanism, and the bottom of the crucible was raised to the upper edge of the temperature gradient zone in a descending furnace, and then the temperature was increased.

[0053] (3) The temperature of the high temperature zone of the descending furnace was set to be 550° C., and the mixed powder was heated to a molten state, and kept for 30 h.

[0054] (4) The quartz crucible was lowered at a speed of 0.2 mm/h through the down mechanism.

[0055] (5) After the crucible was lowered to a preset distance, the temperature was decreased slowly to room temperature, and then the crucible was taken out and transferred to a glove box. The crystal was taken out by breaking the crucible, cut, ground and polished to be processed into a wafer sample, and the remaining transparent scraps were taken and ground to be processed into a powder sample.

[0056] The obtained crystals are of good quality (see FIG. 1). When the sample is excited by a 300 nm light source, the self-trapped excitons with an emission center at 446 nm and a range of 350-550 nm are shown to emit light (see FIG. 3). The emission spectra under X-ray excitation shows similar results to the fluorescence spectra, indicating an absence of obvious structural defects in the crystals (see FIG. 4).