CN114622268B - Large-size multi-component chloride scintillation crystal and preparation method and application thereof - Google Patents

Large-size multi-component chloride scintillation crystal and preparation method and application thereof Download PDF

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CN114622268B
CN114622268B CN202210308214.XA CN202210308214A CN114622268B CN 114622268 B CN114622268 B CN 114622268B CN 202210308214 A CN202210308214 A CN 202210308214A CN 114622268 B CN114622268 B CN 114622268B
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李静
王彪
温航
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Abstract

The invention provides a large-size multi-component chloride scintillation crystal and a preparation method and application thereof. The scintillation crystal has the general formula: ( 6 Li x Cs 1‑x ) 2 ZnCl 4 X is more than or equal to 0 and less than or equal to 1; the diameter of the scintillation crystal is 12-50mm, and the length of the scintillation crystal is 20-150mm. The invention also provides a growth method of the large-size multi-component chloride scintillation crystal, which adopts a vertical Bridgman method, a Czochralski method or an edge-defined film feeding method to grow the crystal. Chloride scintillation crystals of the invention: ( 6 Li x Cs 1‑x ) 2 ZnCl 4 Is not easy to deliquesce, can realize the detection of neutrons and/or gamma rays, especially crystals (A) 6 Li x Cs 1‑x ) 2 ZnCl 4 And (x is more than 0 and less than 1), the double detection of neutrons and gamma rays can be realized simultaneously.

Description

Large-size multi-component chloride scintillation crystal and preparation method and application thereof
Technical Field
The invention relates to a large-size multi-component chloride scintillation crystal and a preparation method and application thereof, belonging to the technical field of crystal growth.
Background
The scintillating material is a material which can absorb high-energy particles or rays to emit light photons, wherein the ultrafast scintillating material refers to a material with a response time less than 4ns (10) -9 s) of a scintillator material. The material plays a role in prop in Pulsed radiation detection (Pulsed radiation detection), solar neutrino detection, reaction kinetics, inertial confinement nuclear fusion and cosmic ray research.
The current scintillating materials comprise three main types, namely organic scintillators, inorganic scintillators and composite scintillators. The organic scintillator has good energy resolution but low radiation resistance intensity, and is not beneficial to long-time use; the inorganic scintillators can be classified into oxide scintillators and halide scintillators according to different compositions, and the oxide scintillators have stable physical and chemical properties but low light yield and poor energy resolution, so that the halide scintillators serving as novel scintillating materials with high light yield and high energy resolution become a hotspot of research at present.
The ability to resolve and detect neutrons and gamma rays, and particularly the ability to resolve and detect neutrons and gamma rays simultaneously, is an important research topic of radiation detection technology today. Among them, inorganic scintillation crystals have outstanding advantages and have attracted much attention. Scintillation crystals capable of detecting both neutrons and gamma rays have been an important research topic in the field of radiation detection for nearly 20 years. The first scintillation crystal used was LiBaF 3 Ce scintillation crystal, which has a significant difference between the core valence light emission of the fast light-emitting component and the exciton light emission of the slow light-emitting component under the excitation of gamma rays and thermal neutrons, and can clearly distinguish gamma rays and thermal neutrons, but Ce ion as an activator is difficult to be dissolved in LiBaF in solid solution 3 In the structure; secondly, the luminescence peak of the core valence and the absorption spectrum of Ce are overlapped, thereby limiting the practical application of the luminescence peak. Elpasolite scintillation crystal Cs 2 LiYCl 6 Ce (CLYC) has attracted the attention of researchers since its scintillation property was discovered, has a definite neutron-gamma pulse shape resolution, and is expected to be a scintillation crystal promising in neutron and gamma ray screening, but elpasolite-type crystals all face the problem of deliquescence, increasing the difficulty of crystal processing and growth, and are also a scintillation crystal that is not uniformly molten, and compounds of other phases grow during crystal growth, which is a main cause of defects in the crystal and limits the growth of large-size single crystals.
Therefore, the development of a novel scintillation crystal with a large size can realize the resolution and detection of neutrons and gamma rays, and especially can use a single detection material to carry out dual detection of neutrons and gamma rays, which has important significance. The invention is therefore proposed.
Disclosure of Invention
Aiming at the defects of the prior art, the invention provides a large-size multi-component chloride scintillation crystal and a preparation method and application thereof. Compared with the existing halide scintillation crystal, the chloride scintillation crystal (A) of the invention 6 Li x Cs 1-x ) 2 ZnCl 4 Not easy to deliquesce, and can realize the detection of neutrons and/or gamma rays, especially crystals 6 Li x Cs 1-x ) 2 ZnCl 4 And (x is more than 0 and less than 1), the dual detection of neutrons and gamma rays can be realized simultaneously.
The technical scheme of the invention is as follows:
a large-size multicomponent chloride scintillation crystal having the general formula: ( 6 Li x Cs 1-x ) 2 ZnCl 4 X is more than or equal to 0 and less than or equal to 1; the diameter of the scintillation crystal is 12-50mm, and the length of the scintillation crystal is 20-150mm.
Preferably, according to the invention, when x is 0, the scintillation crystal is Cs 2 ZnCl 4 Is an orthorhombic system, a Pnam space group, and a point group
Figure BDA0003566671020000021
Cell parameter is->
Figure BDA0003566671020000022
From separated [ ZnCl ] 4 ] 2- Tetrahedra and interstitial Cs cations between them; the crystal has a core band-valence band luminescence with extremely short decay time, the decay time is 1.6ns, the luminescence process can occur under the irradiation of gamma rays, and the detection of the gamma rays can be realized.
According to the invention, when x is between 0 and 1, the scintillation crystal is preferably (A) 6 Li x Cs 1-x ) 2 ZnCl 4 The crystal simultaneously has 6 Li and Cs, the neutron signal and the gamma ray can be detected.
Preferably, according to the invention, when x is 1, theThe scintillation crystal is 6 Li 2 ZnCl 4 The crystal can realize the detection of neutrons.
The invention also provides a growth method of the large-size multi-component chloride scintillation crystal, which comprises the following steps:
(1) According to the stoichiometric ratio, csCl as the raw material, 6 LiCl、ZnCl 2 Mixing, placing into quartz ampoule tube, vacuumizing, and sealing; putting the sealed quartz ampoule tube into a resistance furnace, and performing crystal phase pre-synthesis to obtain (A) 6 Li x Cs 1-x ) 2 ZnCl 4 Polycrystalline materials;
(2) The crystal growth is carried out by a vertical Bridgman method, a Czochralski method or an edge-defined thin film feeding method.
According to the invention, the vacuum pumping in the step (1) is preferably performed under the heating condition of 150 ℃ until the vacuum degree is 10 -6 mbar。
Preferably, according to the present invention, the pre-synthesis step in step (1) is: putting the sealed quartz ampoule tube into a resistance furnace, heating to 500-650 ℃ at the speed of 50-100 ℃/h, then cooling to 100-200 ℃ at the speed of 30-50 ℃/h, heating to 500-650 ℃ at the speed of 50-100 ℃/h, circulating for three times, keeping the temperature at 500-650 ℃ for 10 hours, and then cooling to room temperature at the speed of 1-15 ℃/h to obtain (A) 6 Li x Cs 1-x ) 2 ZnCl 4 Polycrystalline materials.
Preferably, in step (2), the step of performing crystal growth by using the vertical bridgeman method comprises:
the compound obtained in step (1) contains 6 Li x Cs 1-x ) 2 ZnCl 4 Placing a quartz ampoule tube made of polycrystalline materials into a Bridgman single crystal growth furnace, and performing single crystal growth according to the descending speed of 0.2-0.8 mm/h; the crystal growth temperature is 550-650 ℃; after the growth is finished, reducing the furnace temperature to room temperature, and taking out crystals; the cooling rate is 5-20 ℃/h.
Preferably, in step (2), the crystal growth by the czochralski method comprises the following steps:
(I) aThe longitudinal temperature gradient of the Czochralski method single crystal growth furnace is 10-30 ℃/cm, and the transverse temperature gradient is 1-5 ℃/cm; then in a nitrogen atmosphere, the obtained (A) 6 Li x Cs 1-x ) 2 ZnCl 4 Putting a polycrystalline material into a quartz crucible, putting the quartz crucible into a quartz ampoule tube, then putting the quartz ampoule tube into a single crystal growth furnace, vacuumizing the quartz ampoule tube and filling protective gas argon, heating and melting the polycrystalline material in a medium-frequency reaction heating mode, cooling the polycrystalline material after full melting to condense the polycrystalline material, repeatedly heating and melting and cooling to condense, and discharging bubbles in a melt; then the melt is overheated by 5 to 10 ℃ and is kept constant for 10 to 20min to obtain (A) 6 Li x Cs 1-x ) 2 ZnCl 4 Melting liquid;
(II) with Cs 2 ZnCl 4 For the seed crystal to descend vertically to 6 Li x Cs 1-x ) 2 ZnCl 4 In the melt, the top end of the seed crystal is just contacted with the liquid level to stop, and then the single crystal growth is carried out;
the conditions of the single crystal growth process are as follows: the growth temperature is 500-650 ℃; firstly, seeding growth is carried out under the conditions that the rotating speed is 20-40 r/min and the pulling speed is 4-5mm/h, when the diameter of the pulled crystal is enlarged to the target diameter, neck-closing growth is carried out, the pulling speed is 8-10mm/h when the neck is closed, and the rotating speed is 20-40 r/min; when the diameter of the crystal is narrowed to 5-7mm, slowly cooling at the speed of 2-6 ℃/h, and carrying out shouldering growth, wherein the pulling speed is 3-6mm/h and the rotating speed is 20-40 r/min; until the diameter of the crystal is the same as the target diameter, carrying out equal-diameter growth, wherein the pulling speed is 4-8mm/h and the rotating speed is 20-40 r/min during the equal-diameter growth; and lifting the crystal when the crystal grows to a preset size.
And (III) after the crystal is extracted and removed, cooling the temperature of the growth furnace to room temperature, and taking out the crystal to obtain the large-size multi-component chloride scintillation crystal.
Preferably, the extraction and desorption step in the step (II) is as follows: raising the pulling speed to 8-12mm/h, raising the temperature to 5-15 ℃ after 20-30min of pulling, keeping the temperature for 2h, and extracting crystals from the melt.
Preferably, in the step (iii), the temperature reduction step is: reducing the temperature to 300 ℃ at the speed of 5-8 ℃/h, then reducing the temperature to 50-60 ℃ at the speed of 10-20 ℃/h, and then naturally cooling to room temperature.
Preferably, in step (2), the step of growing the crystal by using the edge-defined thin film feeding method comprises:
(i) The longitudinal temperature gradient of the single crystal growth furnace by the edge-defined film feeding method is 10-30 ℃/cm, and the transverse temperature gradient is 1-5 ℃/cm;
will be (A) and (B) 6 Li x Cs 1-x ) 2 ZnCl 4 Placing the polycrystal material into a quartz crucible, placing a mould on the raw material, sealing and packaging the raw material in an installing and cutting tube, vacuumizing to exhaust air, filling nitrogen, overheating the melt by 10-30 ℃, keeping the temperature for 1-3 hours, and fully melting the material to obtain a molten liquid; adjusting the temperature to 5-45 ℃ above the melting point of the crystals, and then adding Cs 2 ZnCl 4 Placing the seed crystal above the capillary hole, descending to stop contacting with liquid in the capillary, then carrying out seeding growth, and carrying out neck growth after the diameter of the crystal to be led out is enlarged to be the same as that of the die; when the diameter of the seed crystal is narrowed to 5-8mm, shouldering is carried out until the diameter of the crystal is the same as that of the mold, the shouldering stage is completed, the stage of equal-diameter growth is carried out, the equal-diameter growth grows along the mold, and the stage of ending is carried out after the equal-diameter growth; the pulling speed at the stages of seeding, neck closing, shoulder putting, equal-diameter growth and ending is 2-10mm/h;
(ii) After the crystal grows to the required size, extracting the crystal from the melt; and (4) after the crystal is extracted and removed, cooling the growth furnace to room temperature, and taking out the crystal to obtain the large-size multi-component chloride scintillation crystal.
Preferably, according to the invention, the pulling speed in the seeding growth in step (i) is 4-5mm/h; the pulling speed of the neck growth is 8-10mm/h; the pulling speed of the shouldering growth is 3-6mm/h; the drawing speed of the equal-diameter growth is 3-6mm/h.
Preferably according to the invention, the stripping step in step (ii) is: after the crystal grows to the required size, heating to 10-20 ℃, keeping the temperature for 5-20 minutes, and extracting the crystal from the melt; the cooling step is as follows: reducing the temperature to 300 ℃ at the speed of 5-8 ℃/h, then reducing the temperature to 50-60 ℃ at the speed of 10-20 ℃/h, and then naturally cooling to room temperature.
According to the invention, the large-size multi-component chloride scintillation crystal is applied to neutron detection and gamma ray detection.
According to the application of the invention, preferably, the scintillation crystal is Cs 2 ZnCl 4 For the detection of gamma rays; the scintillation crystal is (A) 6 Li x Cs 1-x ) 2 ZnCl 4 (x is more than 0 and less than 1) and is used for neutron signal and gamma ray double detection; the scintillation crystal is Li 2 ZnCl 4 For the detection of neutrons.
The principle of the invention is as follows:
the invention provides three kinds of growth M 2 ZnCl 4 (M is Cs and/or 6 Li) large-size single crystal, in which the main base material is Cs 2 ZnCl 4 The crystal is irradiated by external high-energy particles such as gamma rays, electrons in a Cs 5p orbit of the crystal are transited into a Cl 3p valence band, namely core band holes are generated in the Cs 5p orbit, and then in a very short time, electrons in a higher energy state in the Cl 3p orbit fill the holes and simultaneously emit photons, namely the process is that the core band-valence band of the crystal emits light. The time of the luminescence process is extremely short and is 1.6ns; when the crystal is grown to be ( 6 Li x Cs 1-x ) 2 ZnCl 4 (x is more than 0 and less than 1), cs and 6 li element due to 6 The presence of Li isotopes will react nuclear with neutrons:
Figure BDA0003566671020000041
the difference of decay time exists between the luminescence process of the reaction and the core band-valence band of the crystal, and the neutron and gamma double detection can be realized by analyzing the decay time; 6 Li 2 ZnCl 4 can be used for neutron detection, first 6 Li 2 ZnCl 4 In crystals of 6 The content of Li element can reach 29%, the capture efficiency of neutron is ensured, and the method is used 6 After substitution of Li by the Li isotope, a nuclear reaction occurs: />
Figure BDA0003566671020000042
The reaction energy of the reaction is 4.786MeV, and the large reaction can more easily cause the crystal lattice to generate stimulated transition so as to emit photons, thereby realizing the detection of neutrons.
The invention has the following technical characteristics and beneficial effects:
compared with the existing halide scintillation crystal, the scintillation crystal Cs of the invention 2 ZnCl 4 Crystalline and lithium-doped Cs 2 ZnCl 4 The gamma ray scintillation decay time of the crystal is very short, and the rapid decay process can be used as a distinguishing means of pulse shape discrimination method for distinguishing radiation signal according to time, and can implement detection of gamma ray, and (C), (D) 6 Li x Cs 1-x ) 2 ZnCl 4 (x is more than 0 and less than 1), cs and 6 li element can realize double detection of neutrons and gamma rays; secondly, the crystal of the invention is not deliquescent, and the characteristic solves the problem of difficult crystal testing, processing and application.
Drawings
FIG. 1 shows Cs prepared in example 1 2 ZnCl 4 A photograph of the crystal.
FIG. 2 shows Cs prepared in example 1 2 ZnCl 4 XRD spectrum of crystal.
FIG. 3 shows Cs prepared in example 1 2 ZnCl 4 Photoluminescence spectra of the crystals.
FIG. 4 shows Cs prepared in example 2 2 ZnCl 4 A photograph of the crystal (left) and a wafer after crystal cut polishing (right).
FIG. 5 shows Cs prepared in example 2 2 ZnCl 4 XRD spectrum of crystal.
FIG. 6 shows Cs obtained in example 2 2 ZnCl 4 Photoluminescence spectra of the crystals.
FIG. 7 shows Cs prepared in example 3 2 ZnCl 4 A photograph of the crystal.
FIG. 8 shows Cs obtained in example 3 2 ZnCl 4 XRD spectrum of crystal.
FIG. 9 is a photograph of a photograph obtained by the preparation of example 4 6 Li 0.4 Cs 1.6 ZnCl 4 A photograph of the crystal.
FIG. 10 is a photograph of a photograph obtained by the preparation of example 4 6 Li 0.4 Cs 1.6 ZnCl 4 XRD spectrum of crystal.
FIG. 11 is a photograph of a photograph obtained by the preparation of example 4 6 Li 0.4 Cs 1.6 ZnCl 4 Photoluminescence spectra of the crystals.
Detailed Description
The present invention will be further described with reference to the following examples and accompanying drawings, but is not limited thereto.
Meanwhile, the raw materials used in the following examples are all conventional raw materials and can be obtained commercially; the methods are prior art unless otherwise specified.
Example 1
Large-size Cs 2 ZnCl 4 The preparation method of the crystal adopts a vertical Bridgman method to grow the crystal, and comprises the following steps:
(1) In a glove box filled with helium, the mixture was stirred at the molar ratio CsCl: znCl 2 Ratio of =2, csCl, znCl 2 Putting into a quartz ampoule tube, connecting the quartz ampoule tube with a vacuum pump, vacuumizing at 150 deg.C for 4 hr until the vacuum degree is reduced to 10 -6 mbar, sealing the quartz tube using a hydrogen flame; placing the sealed quartz ampoule tube into a resistance furnace, heating to 650 ℃ at the speed of 80 ℃/h, then cooling to 500 ℃ at the speed of 30 ℃/h, heating to 650 ℃ at the speed of 80 ℃/h, circulating for three times, keeping the temperature at 650 ℃ for 10 hours, then cooling to room temperature at the speed of 10 ℃/h to obtain Cs 2 ZnCl 4 Polycrystalline material, which is not necessarily taken out of the quartz ampoule tube, is directly used for the next step.
(2) Adding Cs in the step (1) 2 ZnCl 4 Placing a quartz ampoule tube of the polycrystalline material into a Bridgman single crystal growth furnace, and slowly descending at a descending speed of 0.4mm/h to perform single crystal growth at a crystal growth temperature of 625 ℃.
(3) Slowly cooling the furnace to room temperature at a rate of 10 ℃/h after the growth is finished, and cooling the obtained productCutting the quartz ampoule tube on a diamond wire cutting machine, taking out the crystal to obtain Cs 2 ZnCl 4 And (4) crystals.
Cs prepared in this example 2 ZnCl 4 The photograph of the crystal is shown in FIG. 1, and it can be seen from FIG. 1 that the size of the obtained crystal is
Figure BDA0003566671020000061
The grown crystal is crack-free, and the fact that the method can obtain a crack-free high-quality large-block single crystal is proved. FIG. 2 is the powder XRD diffraction result of the single crystal prepared in this example, which is well matched with standard PDF card, and thus the grown crystal is Cs 2 ZnCl 4 Single crystal, no other crystal phase, fig. 3 is a photoluminescence spectrum of the crystal excited at 269nm, and the result shows that the emission wavelength range of the crystal can achieve good wavelength matching with a Si photomultiplier.
Example 2
Large-size Cs 2 ZnCl 4 The preparation method of the crystal adopts a pulling method to grow the crystal, and comprises the following steps:
(1) In a glove box filled with helium, the mixture was stirred at the molar ratio CsCl: znCl 2 Ratio of =2, csCl, znCl 2 Putting into a quartz ampoule tube, connecting the quartz ampoule tube with a vacuum pump, vacuumizing at 150 deg.C for 4 hr until the vacuum degree is reduced to 10 -6 mbar, sealing the quartz tube using a hydrogen flame; placing the sealed quartz ampoule tube into a resistance furnace, heating to 650 ℃ at the speed of 80 ℃/h, then cooling to 500 ℃ at the speed of 30 ℃/h, heating to 650 ℃ at the speed of 80 ℃/h, circulating for three times, keeping the temperature at 650 ℃ for 10 hours, then cooling to room temperature at the speed of 10 ℃/h to obtain Cs 2 ZnCl 4 Polycrystalline materials.
(2) The longitudinal temperature gradient of the single crystal growing furnace of the pulling method is 12 ℃/cm, and the transverse temperature gradient is 2 ℃/cm;
the obtained Cs was put into a glove box filled with nitrogen gas 2 ZnCl 4 Placing the polycrystal material into a quartz crucible, placing the quartz crucible into a quartz ampoule tube, and thenPlacing a quartz ampoule tube in a single crystal growth furnace, vacuumizing the quartz ampoule tube, filling protective gas nitrogen, heating and melting a polycrystalline material in a medium-frequency reaction heating mode, cooling the polycrystalline material after the polycrystalline material is completely melted to be condensed, heating again to be completely melted, and repeating the process for a plurality of times to completely exhaust bubbles generated in a melt; then the melt is overheated by 5 ℃ and kept at the constant temperature for 15min to obtain Cs 2 ZnCl 4 Melting liquid;
(3) At 625 deg.C, adding Cs 2 ZnCl 4 The seed crystal vertically descends to Cs 2 ZnCl 4 In the melt, the top end of the seed crystal is just contacted with the liquid level to stop, then seeding is carried out under the conditions that the rotating speed is 20 r/min and the pulling speed is 5mm/h, the pulling speed is reduced to 4mm/h when the crystal starts to grow along the seed crystal, the diameter of the led-out crystal is enlarged to 20mm, after the crystal grows for 30min, the pulling speed is controlled to 8mm/h, the rotating speed is 30 r/min and the growth temperature is 630 ℃, neck growth is carried out, and therefore dislocation and other defects in the crystal are reduced; when the neck is contracted and grows until the diameter of the crystal is 6mm, adjusting the pulling speed to be 4mm/h and the rotating speed to be 30 revolutions per minute, and carrying out shouldering growth at the cooling rate of 5 ℃/h; until the diameter of the crystal reaches 20mm, carrying out equal-diameter growth under the conditions that the growth temperature is 625 ℃, the pulling speed is 5mm/h and the rotating speed is 30 r/min; and (3) lifting and removing when the crystal grows to 30mm, increasing the lifting speed to 8mm/h, lifting for 20min, then heating to 10 ℃, keeping the temperature for 2h, and lifting and removing the crystal from the melt.
(4) Pulling off the crystal, cooling to 300 deg.C at a rate of 5 deg.C/h, cooling to 50 deg.C at a rate of 10 deg.C/h to reduce internal stress of the crystal and prevent the crystal from cracking, naturally cooling to room temperature, taking out the crystal from quartz ampoule tube to obtain Cs 2 ZnCl 4 And (4) crystals.
Cs prepared in this example 2 ZnCl 4 The photograph of the single crystal is shown in FIG. 4, and it can be seen from FIG. 4 that the size of the obtained single crystal is
Figure BDA0003566671020000071
Fig. 4 shows the wafer after crystal cutting and polishing. FIG. 5 shows the result of powder XRD diffraction analysis of the crystal, according to FIG. 5As can be seen, the Czochralski method grows crystals and Cs 2 ZnCl 4 The crystal PDF card is well matched, and the crystal PDF card proves that the crystal can be prepared by the pulling method. FIG. 6 shows the results of photoluminescence measurements on the wafer, and it can be seen from FIG. 6 that the crystal shows a peak with a central wavelength of 495nm under 266nm excitation, which is substantially the same as the result of example 1, and can be well matched with a Si photomultiplier.
Example 3
Large-size Cs 2 ZnCl 4 The preparation method of the crystal adopts an edge-defined film feeding method to grow the crystal, and comprises the following steps:
(1) In a glove box filled with helium, the molar ratio CsCl: znCl 2 Ratio of =2, csCl, znCl 2 Putting into a quartz ampoule tube, connecting the quartz ampoule tube with a vacuum pump, vacuumizing at 150 deg.C for 4 hr until the vacuum degree is reduced to 10 -6 mbar, sealing the quartz tube using a hydrogen flame; placing the sealed quartz ampoule tube into a resistance furnace, heating to 650 ℃ at the speed of 80 ℃/h, then cooling to 500 ℃ at the speed of 30 ℃/h, heating to 650 ℃ at the speed of 80 ℃/h, circulating for three times, keeping the temperature at 650 ℃ for 10 hours, then cooling to room temperature at the speed of 10 ℃/h to obtain Cs 2 ZnCl 4 Polycrystalline materials.
(2) The longitudinal temperature gradient of the single crystal growth furnace by the edge-defined film feeding method is 10 ℃/cm, and the transverse temperature gradient is 2 ℃/cm
The obtained Cs was put in a glove box filled with nitrogen gas 2 ZnCl 4 Placing a polycrystalline material into a quartz crucible with an edge-defined thin film feeding method, placing a mold on a raw material, sealing and packaging in an installing and cutting tube, vacuumizing to discharge air, filling nitrogen, heating and melting the polycrystalline material in a medium-frequency reaction heating mode, and overheating for 2 hours at 10 ℃ to fully melt the material to obtain a molten liquid; the temperature was adjusted to 630 ℃ and Cs was added 2 ZnCl 4 Placing seed crystal above the capillary, slowly lowering to stop contacting with liquid in the capillary, seeding at 4mm/h to grow crystal, enlarging diameter of the crystal to be the same as that of the mold, and increasing pulling speed to 8mm/h, performing neck-in growth until the diameter of the crystal is 6mm, so as to reduce dislocation and other defects in the crystal; after the diameter of the crystal reaches 6mm, shouldering growth is carried out by controlling the pulling speed to be 4mm/h and the growth temperature to be 625 ℃ until the diameter of the crystal is the same as the diameter of the die, the shouldering stage is completed, and the equal-diameter growth is carried out under the conditions that the temperature is 625 ℃ and the pulling speed is 4 mm/h.
(3) When the crystal grows to 30mm, the crystal can be pulled off, the pulling speed is increased to 8mm/h, the temperature is raised to 10 ℃ after 20min of pulling, the temperature is kept constant for 20min, and the crystal is pulled off from the melt; after the crystal is extracted, the temperature is reduced to 300 ℃ at the speed of 5 ℃/h, then the temperature is reduced to 50 ℃ at the speed of 10 ℃/h, so that the internal stress of the crystal is reduced, the crystal is prevented from cracking, then the crystal is naturally cooled to room temperature, and the crystal is taken out from a quartz ampoule tube to obtain Cs 2 ZnCl 4 And (4) crystals.
Cs prepared in this example 2 ZnCl 4 A photograph of the single crystal is shown in FIG. 7, and it can be seen from FIG. 7 that the size of the obtained single crystal is
Figure BDA0003566671020000082
FIG. 8 shows the result of powder XRD diffraction analysis of the crystal, and from the result of FIG. 8, it can be seen that the crystal grown by the edge-defined thin film feeding method is Cs 2 ZnCl 4 Single crystal, which confirmed that the method can achieve the production of single crystals.
Example 4
Large-size 6 Li 0.4 Cs 1.6 ZnCl 4 (x = 0.2) a method for producing a crystal by a vertical bridgeman method, comprising the steps of:
(1) In a helium-filled glove box according to the molar ratio 6 LiCl：CsCl：ZnCl 2 Ratio of =0.4 6 LiCl、CsCl、ZnCl 2 Putting into a quartz ampoule tube, connecting the quartz ampoule tube with a vacuum pump, vacuumizing for 6h under the heating condition of 150 deg.C, and cooling to 10 deg.C -6 mbar, sealing the quartz tube using a hydrogen flame; the sealed quartz ampoule tube is put into a resistance furnace, heated to 600 ℃ at the speed of 80 ℃/h, and then heated at the speed of 30 ℃/hCooling to 400 ℃, then heating to 600 ℃ at the speed of 80 ℃/h, circulating for three times, keeping the temperature at 600 ℃ for 10 hours, and then cooling to room temperature at the speed of 10 ℃/h to obtain the final product 6 Li 0.4 Cs 1.6 ZnCl 4 Polycrystalline material, which is not necessarily taken out of the quartz ampoule tube, is directly used for the next step.
(2) Step (1) comprises 6 Li 0.4 Cs 1.6 ZnCl 4 Putting a quartz ampoule tube made of polycrystalline materials into a Brickmann single crystal growth furnace, and slowly descending at a descending speed of 0.4mm/h to perform single crystal growth at a crystal growth temperature of 590 ℃.
(3) Slowly cooling the furnace temperature to room temperature at the speed of 10 ℃/h after the growth is finished, cutting the cooled quartz ampoule tube on a diamond wire cutting machine, and taking out crystals to obtain the quartz glass tube 6 Li 0.4 Cs 1.6 ZnCl 4 And (4) crystals.
Prepared in this example 6 Li 0.4 Cs 1.6 ZnCl 4 The photograph of the crystal is shown in FIG. 9, and it can be seen from FIG. 9 that the size of the resulting crystal is
Figure BDA0003566671020000081
FIG. 10 is a powder XRD diffraction result of the single crystal produced in this example, from which it can be seen that the standard Cs is satisfied 2 ZnCl 4 The PDF card of the crystal is well matched, and the results prove that 6 Doping of LiCl the grown crystals did not change the crystal structure and doping was feasible. FIG. 11 is a schematic view of 6 Li 0.4 Cs 1.6 ZnCl 4 Photoluminescence spectrum of the crystal under the excitation of 310nm, 6 doping of Li leads to Cs 2 ZnCl 4 The crystal shows a blue shift in the luminescence peak, with the center wavelength shifted from 490nm to 378nm, which also indicates that 6 Li successfully enters into crystal lattice, and proves that the vertical Bridgman method can grow 6 Li 0.4 Cs 1.6 ZnCl 4 And (4) crystals. When the luminescence center is shifted to 378nm, the crystal can realize good wavelength matching with a photomultiplier tube (PMT). />

Claims (7)

1. BigA size multicomponent chloride scintillation crystal, wherein the scintillation crystal has the general formula: ( 6 Li x Cs 1-x ) 2 ZnCl 4 X is between 0 and 1, and the crystal simultaneously has 6 Two elements of Li and Cs; the diameter of the scintillation crystal is 12-50mm, and the length of the scintillation crystal is 20-150mm.
2. A method of growing a large-size multi-component chloride scintillation crystal of claim 1, comprising the steps of:
(1) According to the stoichiometric ratio, csCl as the raw material, 6 LiCl、ZnCl 2 Mixing, placing into quartz ampoule tube, vacuumizing, and sealing; putting the sealed quartz ampoule tube into a resistance furnace, and performing crystal phase pre-synthesis to obtain (A) 6 Li x Cs 1-x ) 2 ZnCl 4 Polycrystalline materials;
(2) The crystal growth is carried out by a vertical Bridgman method, a Czochralski method, an aqueous solution method or an edge-defined film feeding method.
3. The method for growing large-size multi-component chloride scintillation crystals of claim 2, wherein the step (1) of evacuating is performed by heating at 150 ℃ and evacuating to a vacuum degree of 10 -6 mbar；
The pre-synthesis steps are as follows: putting the sealed quartz ampoule tube into a resistance furnace, heating to 500-650 ℃ at a speed of 50-100 ℃/h, then cooling to 100-200 ℃ at a speed of 30-50 ℃/h, heating to 500-650 ℃ at a speed of 50-100 ℃/h, circulating for three times, keeping the temperature at 500-650 ℃ for 10 hours, and then cooling to room temperature at a speed of 1-15 ℃/h to obtain the product (A) 6 Li x Cs 1-x ) 2 ZnCl 4 Polycrystalline materials.
4. The method for growing a large-size multi-component chloride scintillation crystal according to claim 2, wherein in step (2), the step of growing the crystal by the vertical Bridgman method comprises:
in the step (1)Obtained a mixture comprising 6 Li x Cs 1-x ) 2 ZnCl 4 Putting a quartz ampoule tube made of polycrystalline materials into a Bridgman single crystal growth furnace, and performing single crystal growth by descending at a descending speed of 0.2-0.8 mm/h; the crystal growth temperature is 550-650 ℃; after the growth is finished, reducing the furnace temperature to room temperature, and taking out crystals; the cooling rate is 5-20 ℃/h.
5. The method for growing a large-size multi-component chloride scintillation crystal according to claim 2, wherein in the step (2), the step of growing the crystal by using a czochralski method comprises:
the longitudinal temperature gradient of a single crystal growing furnace by a pulling method is 10-30 ℃/cm, and the transverse temperature gradient is 1-5 ℃/cm; then in a nitrogen atmosphere, the obtained (A) 6 Li x Cs 1-x ) 2 ZnCl 4 Putting a polycrystalline material into a quartz crucible, putting the quartz crucible into a quartz ampoule tube, then putting the quartz ampoule tube into a single crystal growth furnace, vacuumizing the quartz ampoule tube and filling protective gas nitrogen, heating and melting the polycrystalline material in a medium-frequency reaction heating mode, cooling the polycrystalline material after full melting to condense the polycrystalline material, repeatedly heating and melting and cooling to condense, and discharging bubbles in a melt; then the melt is overheated by 5 to 10 ℃ and is kept constant for 10 to 20min to obtain (A) 6 Li x Cs 1-x ) 2 ZnCl 4 Melting liquid;
(II) with Cs 2 ZnCl 4 For the seed crystal to descend vertically to 6 Li x Cs 1-x ) 2 ZnCl 4 In the melt, the top end of the seed crystal is just contacted with the liquid level to stop, and then the single crystal growth is carried out;
the conditions of the single crystal growth process are as follows: the growth temperature is 500-650 ℃; firstly, seeding growth is carried out under the conditions that the rotating speed is 20-40 r/min and the pulling speed is 4-5mm/h, when the diameter of the pulled crystal is enlarged to the target diameter, neck-closing growth is carried out, the pulling speed is 8-10mm/h when the neck is closed, and the rotating speed is 20-40 r/min; when the diameter of the crystal is narrowed to 5-7mm, slowly cooling at the speed of 2-6 ℃/h, and carrying out shouldering growth, wherein the pulling speed is 3-6mm/h and the rotating speed is 20-40 r/min; until the diameter of the crystal is the same as the target diameter, carrying out equal-diameter growth, wherein the pulling speed is 4-8mm/h and the rotating speed is 20-40 r/min during the equal-diameter growth; extracting the crystal when the crystal grows to a preset size; the extraction and removal steps are as follows: increasing the pulling speed to 8-12mm/h, after pulling for 20-30min, heating to 5-15 ℃, keeping the temperature for 2h, and pulling out crystals from the melt;
(III) after the crystal is extracted and removed, cooling the temperature of the growth furnace to room temperature, and taking out the crystal to obtain a large-size multi-component chloride scintillation crystal; the cooling step is as follows: reducing the temperature to 300 ℃ at the speed of 5-8 ℃/h, then reducing the temperature to 50-60 ℃ at the speed of 10-20 ℃/h, and then naturally cooling to room temperature.
6. The method for growing a large-size multi-component chloride scintillation crystal according to claim 2, wherein in step (2), the step of growing the crystal by edge-defined thin film feeding comprises:
(i) The longitudinal temperature gradient of the single crystal growth furnace by the edge-defined film feeding method is 10-30 ℃/cm, and the transverse temperature gradient is 1-5 ℃/cm;
will (a) to 6 Li x Cs 1-x ) 2 ZnCl 4 Placing the polycrystal material into a quartz crucible, placing a mould on the raw material, sealing and packaging the raw material in an installing and cutting tube, vacuumizing to exhaust air, filling nitrogen, overheating the melt by 10-30 ℃, keeping the temperature for 1-3 hours, and fully melting the material to obtain a molten liquid; adjusting the temperature to 5-45 ℃ above the melting point of the crystals, and then adding Cs 2 ZnCl 4 Placing the seed crystal above the capillary hole, descending to stop contacting with liquid in the capillary, then carrying out seeding growth, and carrying out neck growth after the diameter of the crystal to be led out is enlarged to be the same as that of the die; when the diameter of the seed crystal is narrowed to 5-8mm, shouldering is carried out until the diameter of the crystal is the same as that of the mold, the shouldering stage is completed, the stage of equal-diameter growth is carried out, the equal-diameter growth grows along the mold, and the stage of ending is carried out after the equal-diameter growth; the pulling speed at the stages of seeding, neck closing, shoulder putting, equal-diameter growth and ending is 2-10mm/h;
the pulling speed during seeding growth is 4-5mm/h; the pulling speed of the neck growth is 8-10mm/h; the pulling speed of the shouldering growth is 3-6mm/h; the pulling speed of the equal-diameter growth is 3-6mm/h;
(ii) After the crystal grows to the required size, extracting the crystal from the melt; after the crystal is extracted, the growing furnace is cooled to the room temperature, and the crystal is taken out, so that the large-size multi-component chloride scintillation crystal is obtained; the extraction and removal steps are as follows: after the crystal grows to the required size, heating to 10-20 ℃, keeping the temperature for 5-20 minutes, and extracting the crystal from the melt; the cooling step is as follows: reducing the temperature to 300 ℃ at the speed of 5-8 ℃/h, then reducing the temperature to 50-60 ℃ at the speed of 10-20 ℃/h, and then naturally cooling to room temperature.
7. Use of the large-size multi-component chloride scintillation crystal of claim 1 for neutron detection, gamma ray detection.
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