CN116607213A - Alkali metal ion doped lanthanum bromide scintillation crystal and growth method thereof - Google Patents
Alkali metal ion doped lanthanum bromide scintillation crystal and growth method thereof Download PDFInfo
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- 239000013078 crystal Substances 0.000 title claims abstract description 117
- XKUYOJZZLGFZTC-UHFFFAOYSA-K lanthanum(iii) bromide Chemical compound Br[La](Br)Br XKUYOJZZLGFZTC-UHFFFAOYSA-K 0.000 title claims abstract description 55
- 238000000034 method Methods 0.000 title claims abstract description 22
- 229910001413 alkali metal ion Inorganic materials 0.000 title abstract description 6
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N silicon dioxide Inorganic materials O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 claims abstract description 67
- 239000010453 quartz Substances 0.000 claims abstract description 60
- 239000002994 raw material Substances 0.000 claims abstract description 38
- 238000001816 cooling Methods 0.000 claims abstract description 18
- 238000010438 heat treatment Methods 0.000 claims abstract description 13
- 238000007789 sealing Methods 0.000 claims abstract description 12
- 239000007787 solid Substances 0.000 claims abstract description 9
- 238000002156 mixing Methods 0.000 claims abstract description 4
- 230000000630 rising effect Effects 0.000 claims description 11
- 238000006467 substitution reaction Methods 0.000 abstract description 9
- 239000000969 carrier Substances 0.000 abstract description 4
- 238000010791 quenching Methods 0.000 abstract description 4
- 230000000171 quenching effect Effects 0.000 abstract description 4
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 25
- 229910052760 oxygen Inorganic materials 0.000 description 25
- 239000001301 oxygen Substances 0.000 description 25
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 19
- BASFCYQUMIYNBI-UHFFFAOYSA-N platinum Chemical compound [Pt] BASFCYQUMIYNBI-UHFFFAOYSA-N 0.000 description 14
- 238000005336 cracking Methods 0.000 description 11
- 229910052697 platinum Inorganic materials 0.000 description 7
- 238000002360 preparation method Methods 0.000 description 7
- 238000005303 weighing Methods 0.000 description 7
- FVAUCKIRQBBSSJ-UHFFFAOYSA-M sodium iodide Chemical compound [Na+].[I-] FVAUCKIRQBBSSJ-UHFFFAOYSA-M 0.000 description 6
- 150000001768 cations Chemical class 0.000 description 5
- 230000000052 comparative effect Effects 0.000 description 4
- NIPNSKYNPDTRPC-UHFFFAOYSA-N N-[2-oxo-2-(2,4,6,7-tetrahydrotriazolo[4,5-c]pyridin-5-yl)ethyl]-2-[[3-(trifluoromethoxy)phenyl]methylamino]pyrimidine-5-carboxamide Chemical compound O=C(CNC(=O)C=1C=NC(=NC=1)NCC1=CC(=CC=C1)OC(F)(F)F)N1CC2=C(CC1)NN=N2 NIPNSKYNPDTRPC-UHFFFAOYSA-N 0.000 description 3
- 238000012360 testing method Methods 0.000 description 3
- 150000001450 anions Chemical class 0.000 description 2
- 238000001514 detection method Methods 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 230000005611 electricity Effects 0.000 description 2
- 150000002500 ions Chemical class 0.000 description 2
- 239000011734 sodium Substances 0.000 description 2
- 235000009518 sodium iodide Nutrition 0.000 description 2
- 229910052684 Cerium Inorganic materials 0.000 description 1
- 229910052783 alkali metal Inorganic materials 0.000 description 1
- 150000001340 alkali metals Chemical class 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- GWXLDORMOJMVQZ-UHFFFAOYSA-N cerium Chemical compound [Ce] GWXLDORMOJMVQZ-UHFFFAOYSA-N 0.000 description 1
- 238000006243 chemical reaction Methods 0.000 description 1
- 239000003153 chemical reaction reagent Substances 0.000 description 1
- 239000008358 core component Substances 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 238000004031 devitrification Methods 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 239000002019 doping agent Substances 0.000 description 1
- 238000005265 energy consumption Methods 0.000 description 1
- 230000009643 growth defect Effects 0.000 description 1
- 238000003384 imaging method Methods 0.000 description 1
- 239000012535 impurity Substances 0.000 description 1
- 238000007689 inspection Methods 0.000 description 1
- 239000000463 material Substances 0.000 description 1
- 238000005259 measurement Methods 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 238000009206 nuclear medicine Methods 0.000 description 1
- 230000003287 optical effect Effects 0.000 description 1
- 239000003208 petroleum Substances 0.000 description 1
- 238000012545 processing Methods 0.000 description 1
- 230000005855 radiation Effects 0.000 description 1
- 230000002285 radioactive effect Effects 0.000 description 1
- 238000011160 research Methods 0.000 description 1
- 229910052716 thallium Inorganic materials 0.000 description 1
- BKVIYDNLLOSFOA-UHFFFAOYSA-N thallium Chemical compound [Tl] BKVIYDNLLOSFOA-UHFFFAOYSA-N 0.000 description 1
Classifications
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- C—CHEMISTRY; METALLURGY
- C30—CRYSTAL GROWTH
- C30B—SINGLE-CRYSTAL GROWTH; UNIDIRECTIONAL SOLIDIFICATION OF EUTECTIC MATERIAL OR UNIDIRECTIONAL DEMIXING OF EUTECTOID MATERIAL; REFINING BY ZONE-MELTING OF MATERIAL; PRODUCTION OF A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; SINGLE CRYSTALS OR HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; AFTER-TREATMENT OF SINGLE CRYSTALS OR A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; APPARATUS THEREFOR
- C30B29/00—Single crystals or homogeneous polycrystalline material with defined structure characterised by the material or by their shape
- C30B29/10—Inorganic compounds or compositions
- C30B29/12—Halides
-
- C—CHEMISTRY; METALLURGY
- C30—CRYSTAL GROWTH
- C30B—SINGLE-CRYSTAL GROWTH; UNIDIRECTIONAL SOLIDIFICATION OF EUTECTIC MATERIAL OR UNIDIRECTIONAL DEMIXING OF EUTECTOID MATERIAL; REFINING BY ZONE-MELTING OF MATERIAL; PRODUCTION OF A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; SINGLE CRYSTALS OR HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; AFTER-TREATMENT OF SINGLE CRYSTALS OR A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; APPARATUS THEREFOR
- C30B11/00—Single-crystal growth by normal freezing or freezing under temperature gradient, e.g. Bridgman-Stockbarger method
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01T—MEASUREMENT OF NUCLEAR OR X-RADIATION
- G01T1/00—Measuring X-radiation, gamma radiation, corpuscular radiation, or cosmic radiation
- G01T1/16—Measuring radiation intensity
- G01T1/20—Measuring radiation intensity with scintillation detectors
- G01T1/202—Measuring radiation intensity with scintillation detectors the detector being a crystal
- G01T1/2023—Selection of materials
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- Chemical & Material Sciences (AREA)
- Crystallography & Structural Chemistry (AREA)
- Organic Chemistry (AREA)
- Engineering & Computer Science (AREA)
- Materials Engineering (AREA)
- Metallurgy (AREA)
- Health & Medical Sciences (AREA)
- Physics & Mathematics (AREA)
- Inorganic Chemistry (AREA)
- Life Sciences & Earth Sciences (AREA)
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- Spectroscopy & Molecular Physics (AREA)
- Crystals, And After-Treatments Of Crystals (AREA)
- Luminescent Compositions (AREA)
Abstract
The application provides an alkali metal ion doped lanthanum bromide scintillation crystal and a growth method thereof, which comprises the following steps: weigh LaBr 3 、CeBr 3 Mixing with MF solid, and loading into quartz crucible; vacuumizing and sealing; heating the sealed quartz crucible in an upper temperature zone of a two-stage temperature-control dropping furnace, keeping constant temperature until the raw materials in the crucible are completely melted after the temperature is raised, and starting a down-leading device to enable the quartz crucible to move from the upper temperature zone to a lower temperature zone for down-leading growth; and cooling to room temperature to obtain the lanthanum bromide scintillation crystal. The application is realized by M + Substitution of part of Ce in lanthanum bromide crystal 3+ Lattice site, br in crystal ‑ The vacancy concentration is greatly increased, the Auger quenching of free carriers is reduced, and the Ce-LaBr is further improved 3 Energy division of crystalsResolution, obtained Ce: laBr 3 The energy resolution of the crystal is less than 2.6% @662keV.
Description
Technical Field
The application relates to the technical field of single crystal growth, in particular to an alkali metal ion doped lanthanum bromide scintillation crystal and a growth method thereof.
Background
The scintillation crystal is a functional material capable of converting high-energy rays such as X rays and gamma rays into ultraviolet-visible light, is widely applied to the fields of security inspection, nuclear medicine imaging, geological exploration, high-energy physics and the like as a core component of high-end detection equipment, and has huge market value and industrial scale.
Cerium doped lanthanum bromide (Ce: laBr) 3 ) The crystal is a novel inorganic scintillation crystal which is currently studied internationally and applied, has the excellent characteristics of high light output, quick decay time, high energy resolution and the like, has the performance which comprehensively surpasses the traditional high light output thallium doped sodium iodide (NaI: tl) scintillation crystal, is the crystal with the most excellent scintillation performance discovered so far, and is widely applied to the fields of deep space exploration, environment detection, petroleum logging, high-energy physics and the like. However Ce: laBr 3 The crystal is difficult to grow, has high anisotropy, has large difference of thermal expansion coefficients along the a axis and the c axis, and is dissociated along the (100) plane, so that the crystal is very easy to crack during the crystal growth and subsequent processing, and it is difficult to obtain a complete and crack-free crystal. How to obtain complete Ce-LaBr with higher energy resolution 3 Crystals have become a hot spot for research at home and abroad in recent years.
Disclosure of Invention
The embodiment of the application aims to provide an alkali metal ion doped lanthanum bromide scintillation crystal and a growth method thereof, so as to improve the energy resolution of the crystal and obtain the complete and cracking-free lanthanum bromide scintillation crystal. The specific technical scheme is as follows:
the first aspect of the present application provides a method for growing a lanthanum bromide scintillation crystal, comprising the steps of:
(1) Weigh LaBr 3 、CeBr 3 Mixing with MF solid, and loading into quartz crucible; wherein the LaBr 3 、CeBr 3 And the purity of MF solid is above 99.99%;
(2) Vacuumizing the quartz crucible and sealing;
(3) Heating the sealed quartz crucible in an upper temperature zone of a two-stage temperature-control dropping furnace, keeping constant temperature until the raw materials in the crucible are completely melted after the temperature is raised, and starting a down-leading device to enable the quartz crucible to move from the upper temperature zone to a lower temperature zone for down-leading growth;
(4) Cooling to room temperature to obtain the lanthanum bromide scintillation crystal;
wherein the MF is selected from at least one of LiF, naF, KF, rbF, csF; the structural formula of the lanthanum bromide scintillation crystal is Ce x M y La (1-x-y) F y Br 3-y Wherein x is more than or equal to 0.005 and less than or equal to 0.2, and y is more than 0 and less than or equal to 0.01.
In some embodiments of the application, the upper temperature zone of the drop down furnace is 820 ℃ to 900 ℃ and the lower temperature zone is 710 ℃ to 780 ℃.
In some embodiments of the application, the constant temperature time is 8h to 24h.
In some embodiments of the application, the downward growth rate is from 0.2mm/h to 0.8mm/h.
In some embodiments of the application, the temperature rising rate of the upper temperature zone of the descent furnace is 20 ℃/h to 50 ℃/h, the temperature rising rate of the lower temperature zone is 20 ℃/h to 50 ℃/h, the temperature falling rate of the upper temperature zone is 15 ℃/h to 50 ℃/h, and the temperature falling rate of the lower temperature zone is 15 ℃/h to 50 ℃/h.
In a second aspect, the application provides a lanthanum bromide scintillation crystal grown by the growth method provided in the first aspect, and the energy resolution is less than 2.6% @662keV.
The application has the beneficial effects that:
the application provides an alkali metal ion doped lanthanum bromide scintillation crystal and a growth method thereof, which comprises the following steps of M + Substitution of part of Ce in the crystal 3+ Lattice site, the two ions have unmatched electricity price, so that Br in the crystal - The vacancy concentration is greatly increased, the Auger quenching of free carriers is reduced, and the Ce-LaBr is further improved 3 Energy resolution of the crystals, obtained Ce: laBr 3 The energy resolution of the crystal is less than 2.6% @662keV. At the same time, the MF is doped with M + Substitution of part of La in crystals 3+ Lattice bit, F - Substitution of part of Br in the crystal - The lattice sites, the doping of anions and cations generate pinning dislocation effect in the crystal, so that cracking is effectively inhibited, and the complete lanthanum bromide scintillation crystal with no cracking and energy resolution less than 2.6 percent@662 keV is obtained. Of course, it is not necessary for any one product or method of practicing the application to achieve all of the advantages set forth above at the same time.
Drawings
In order to more clearly illustrate the embodiments of the application or the technical solutions in the prior art, the drawings used in the embodiments or the description of the prior art will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the application, and other embodiments may be obtained according to these drawings to those skilled in the art.
FIG. 1 shows Ce-LaBr in example 1 3 A scintillation crystal photograph.
FIG. 2 shows Ce-LaBr in example 1 3 Pulse height profile of scintillation crystal.
Detailed Description
The following description of the embodiments of the present application will be made clearly and completely with reference to the accompanying drawings, in which it is apparent that the embodiments described are only some embodiments of the present application, but not all embodiments. All other embodiments obtained by those skilled in the art based on the present application fall within the scope of the present application.
The first aspect of the present application provides a method for growing a lanthanum bromide scintillation crystal, comprising the steps of:
(1) Weigh LaBr 3 、CeBr 3 Mixing with MF solid, and loading into quartz crucible; wherein, laBr 3 、CeBr 3 And the purity of MF solid is above 99.99%;
(2) Vacuumizing the quartz crucible and sealing;
(3) Placing the sealed quartz crucible in an upper temperature region of a two-stage temperature-control dropping furnace, heating, keeping constant temperature until the raw materials in the crucible are completely melted after heating, and starting a down-leading device to enable the quartz crucible to move from the upper temperature region to a lower temperature region for down-leading growth;
(4) And cooling to room temperature to obtain the lanthanum bromide scintillation crystal.
In the above step (1), laBr 3 、CeBr 3 And MF raw materials can be fed according to the required molar metering ratio of each element in the structural formula of the lanthanum bromide scintillation crystal. The used raw material LaBr 3 、CeBr 3 And MF is generally a high purity reagent free of water, having an oxygen content of less than 100ppm and a purity of greater than 99.99%, when the raw material LaBr 3 、CeBr 3 And the purity of MF in the above range can avoid the influence of water molecules and other impurities on the purity of the finally obtained lanthanum bromide scintillation crystal, and avoid the defect of oxide introduction at the same time, thereby improving the optical quality of the lanthanum bromide scintillation crystal. In the step (1), laBr is weighed 3 、CeBr 3 And MF solids, under low water and low oxygen conditions, to avoid reaction of the water and oxygen introduced from the environment with the final lanthanum bromide scintillation crystal, e.g., laBr may be weighed in a glove box having a water content of 0.1ppm or less and an oxygen content of 0.1ppm or less 3 、CeBr 3 And MF solids. The vacuum degree in the step (2) is not particularly limited as long as the object of the present application can be achieved, for example, the vacuum degree is 10 -3 Pa-10 -5 Pa。
In the present application, MF is selected from at least one of LiF, naF, KF, rbF, csF. By doping with MF, M + Substitution of part of La in crystals 3+ Lattice bit, F - Substitution of part of Br in the crystal - Lattice bit due to F - Radius less than Br - Radius, local dislocation distortion of lattice, F - The pinning dislocation function is achieved, and crystal face sliding can be effectively prevented. In addition, M + Substitution of part of the crystalCe 3+ Lattice site, the two ions have unmatched electricity price, so that Br in the crystal - The vacancy concentration is greatly increased, thereby reducing the Auger quenching of free carriers and further improving Ce: laBr 3 Energy resolution of the crystal. It is noted that in the existing growth method of lanthanum bromide scintillation crystal, divalent, trivalent and tetravalent cations are adopted as dopants, and the doped high-valence cations replace part of Ce 3+ After-produced Br - With relatively few vacancies, it is difficult to obtain Ce: laBr with higher energy resolution 3 A scintillation crystal. Compared with the high-valence cations, the application adopts monovalent alkali metal M in MF + Substitution of part of Ce in the crystal 3+ More Br can be generated after lattice site - Vacancy, thus finally obtaining Ce: laBr 3 The energy resolution of the crystal is higher, less than 2.6% @662keV. Meanwhile, the application adopts the co-doping of anions and cations to generate the pinning dislocation effect, and the obtained Ce: laBr 3 The crystal integrity is better, and the yield is higher.
The structural formula of the lanthanum bromide scintillation crystal grown by the growth method is Ce x M y La (1-x-y) F y Br 3-y Wherein x is more than or equal to 0.005 and less than or equal to 0.2, y is more than or equal to 0 and less than or equal to 0.01, and when x or y exceeds the range, the growth defects such as crystal cracking, devitrification and the like are easily caused. By controlling x and y within the above ranges, a complete, crack-free Ce: laBr is advantageously obtained 3 And (5) a crystal.
The sealing method of the quartz crucible of the present application is not particularly limited as long as the object of the present application can be achieved, for example, sealing the quartz crucible using oxyhydrogen flame.
In some embodiments of the application, room temperature refers to about 20 ℃ to 30 ℃.
In some embodiments of the application, the upper temperature zone of the drop-off furnace is 820 ℃ to 900 ℃ and the lower temperature zone is 710 ℃ to 780 ℃. Preferably, the upper temperature zone is 840-880 ℃ and the lower temperature zone is 730-750 ℃. In some embodiments of the application, the constant temperature time is 8h to 24h. Preferably, the constant temperature time is 12h-18h. By controlling the temperature of the upper temperature zone, the temperature of the lower temperature zone and the constant temperature time in the growth process within the ranges, the energy consumption can be reduced to the maximum extent while the raw materials are melted.
In some embodiments of the application, the rate of downdraw growth is from 0.2mm/h to 0.8mm/h. By controlling the speed of the downdraw growth within the above range, the quality of the finally obtained crystal can be ensured.
In some embodiments of the application, the temperature rise rate of the upper temperature zone is 20 ℃/h to 50 ℃/h, the temperature rise rate of the lower temperature zone is 20 ℃/h to 50 ℃/h, the temperature drop rate of the upper temperature zone is 15 ℃/h to 50 ℃/h, and the temperature drop rate of the lower temperature zone is 15 ℃/h to 50 ℃/h. By controlling the temperature rising rate and the temperature lowering rate within the above-described ranges, the integrity of the finally obtained crystal can be ensured.
In a second aspect, the application provides a lanthanum bromide scintillation crystal grown by the growth method provided in the first aspect, and the energy resolution is less than 2.6% @662keV.
Examples
The testing method comprises the following steps:
energy resolution testing
Energy resolution measurements are made by reference to the method prescribed in GB/T13181-2002 chapter 7, the radioactive source employing 137 Cs (662 keV) rays.
The lanthanum bromide scintillation crystals obtained in examples 1 to 6 and comparative example 1, respectively, were tested 137 Energy resolution under Cs radiation source.
In the energy resolution test, the smaller the value of the energy resolution, the higher the energy resolution of the lanthanum bromide scintillation crystal.
Comparative example 1
Ce 0.05 La 0.95 Br 3 Preparation of crystals
In a glove box with the water content less than or equal to 0.1ppm and the oxygen content less than or equal to 0.1ppm, accurately weighing the LaBr with the anhydrous purity of 99.99 percent and the oxygen content less than or equal to 100ppm 3 300 g of raw material CeBr 3 15.8 g of raw material was mixed uniformly in agate-ground platinum and then placed in a quartz crucible which was cleaned beforehand. Taking out the quartz crucible from the glove box, and vacuumizing to 10 -3 Pa, using oxyhydrogen flame to make quartz crucibleThe pipe orifice is sealed, thereby achieving the purpose of isolating water and oxygen. The crucible is placed in an upper temperature zone of a two-stage temperature-control dropping furnace, the temperature of the upper temperature zone is raised to 850 ℃ at the heating rate of 40 ℃/h, the temperature of the lower temperature zone is raised to 730 ℃ at the heating rate of 35 ℃/h, and the temperature is kept constant for 12 hours, so that the raw materials in the crucible are completely melted. Then the quartz crucible is lowered at a lowering speed of 0.5mm/h, the crystal is grown downwards, the quartz crucible is continuously lowered until all the quartz crucible enters a lower temperature zone, and the crystal growth is finished and the lowering is stopped. Then the upper temperature area is cooled to the room temperature at the cooling rate of 20 ℃/h, the lower temperature area is cooled to the room temperature at the cooling rate of 20 ℃/h, and the lanthanum bromide scintillation crystal in the quartz crucible is taken out. The obtained lanthanum bromide scintillation crystal is complete and has no cracking, and the energy resolution is 3.3 percent@662 keV.
Example 1
Ce 0.05 Li 0.004 La 0.946 F 0.004 Br 2.996 Preparation of crystals
In a glove box with the water content less than or equal to 0.1ppm and the oxygen content less than or equal to 0.1ppm, accurately weighing the LaBr with the anhydrous purity of 99.99 percent and the oxygen content less than or equal to 100ppm 3 300 g of raw material CeBr 3 15.8 g of raw material and 0.09 g of LiF raw material are uniformly mixed in agate and platinum, and then are put into a quartz crucible which is cleaned in advance. Taking out the quartz crucible from the glove box, and vacuumizing to 10 -3 Pa, sealing the pipe orifice of the quartz crucible by oxyhydrogen flame, thereby achieving the purpose of isolating water and oxygen. The crucible is placed in an upper temperature zone of a two-stage temperature-control dropping furnace, the temperature of the upper temperature zone is raised to 820 ℃ at a temperature rising rate of 35 ℃/h, the temperature of the lower temperature zone is raised to 750 ℃ at a temperature rising rate of 25 ℃/h, and the temperature is kept constant for 8 hours, so that the raw materials in the crucible are completely melted. Then the quartz crucible is lowered at a lowering speed of 0.5mm/h, the crystal is grown downwards, the quartz crucible is continuously lowered until all the quartz crucible enters a lower temperature zone, and the crystal growth is finished and the lowering is stopped. Then the upper temperature area is cooled to the room temperature at the cooling rate of 20 ℃/h, the lower temperature area is cooled to the room temperature at the cooling rate of 30 ℃/h, and the lanthanum bromide scintillation crystal in the quartz crucible is taken out. The obtained lanthanum bromide scintillation crystal is complete and has no cracking, and the energy resolution is 2.5 percent@662 keV.
Example 2
Ce 0.04 Na 0.005 La 0.955 F 0.005 Br 2.995 Preparation of crystals
In a glove box with the water content less than or equal to 0.1ppm and the oxygen content less than or equal to 0.1ppm, accurately weighing the LaBr with the anhydrous purity of 99.99 percent and the oxygen content less than or equal to 100ppm 3 725 g of raw material CeBr 3 30.3 g of raw material and 0.42 g of NaF raw material are uniformly mixed in agate and platinum, and then are put into a quartz crucible which is cleaned in advance. Taking out the quartz crucible from the glove box, and vacuumizing to 10 -4 Pa, sealing the pipe orifice of the quartz crucible by oxyhydrogen flame, thereby achieving the purpose of isolating water and oxygen. The crucible is placed in an upper temperature zone of a two-stage temperature-control dropping furnace, the temperature of the upper temperature zone is raised to 840 ℃ at the temperature rising rate of 20 ℃/h, the temperature of the lower temperature zone is raised to 730 ℃ at the temperature rising rate of 20 ℃/h, and the temperature is kept constant for 18 hours, so that the raw materials in the crucible are completely melted. Then, the quartz crucible was lowered at a lowering speed of 0.4mm/h, and the crystal was grown downward. And continuing to descend until the quartz crucible completely enters a lower temperature zone, ending the crystal growth, and stopping descending. Then the upper temperature area is cooled to the room temperature at the cooling rate of 30 ℃/h, the lower temperature area is cooled to the room temperature at the cooling rate of 40 ℃/h, and the lanthanum bromide scintillation crystal in the quartz crucible is taken out. The obtained lanthanum bromide scintillation crystal is complete and has no cracking, and the energy resolution is 2.4% @662keV.
Example 3
Ce 0.07 K 0.003 La 0.927 F 0.003 Br 2.997 Preparation of crystals
In a glove box with the water content less than or equal to 0.1ppm and the oxygen content less than or equal to 0.1ppm, accurately weighing the LaBr with the anhydrous purity of 99.99 percent and the oxygen content less than or equal to 100ppm 3 800 g of raw material CeBr 3 60.4 g of raw material and 0.4 g of KF raw material are uniformly mixed in agate and platinum, and then are put into a quartz crucible which is cleaned in advance. Taking out the quartz glass crucible from the glove box, and vacuumizing to 10 -3 Pa, sealing the pipe orifice of the quartz crucible by oxyhydrogen flame, thereby achieving the purpose of isolating water and oxygen. The crucible is placed in an upper temperature zone of a two-stage temperature-controlled dropping furnace, the temperature of the upper temperature zone is increased to 900 ℃ at a heating rate of 30 ℃/h, the temperature of the lower temperature zone is increased to 710 ℃ at a heating rate of 25 ℃/h,keeping the temperature for 16h to completely melt the raw materials in the crucible. Then, the quartz crucible was lowered at a lowering speed of 0.2mm/h, and the crystal was grown downward. And continuing to descend until the quartz crucible completely enters a lower temperature zone, ending the crystal growth, and stopping descending. Then the upper temperature area is cooled to the room temperature at the cooling rate of 40 ℃/h, the lower temperature area is cooled to the room temperature at the cooling rate of 40 ℃/h, and the lanthanum bromide scintillation crystal in the quartz crucible is taken out. The obtained lanthanum bromide scintillation crystal is complete and has no cracking, and the energy resolution is 2.4% @662keV.
Example 4
Ce 0.1 Rb 0.001 La 0.899 F 0.001 Br 2.999 Preparation of crystals
In a glove box with the water content less than or equal to 0.1ppm and the oxygen content less than or equal to 0.1ppm, accurately weighing the LaBr with the anhydrous purity of 99.99 percent and the oxygen content less than or equal to 100ppm 3 300 g of raw material CeBr 3 33.4 g of raw material and 0.09 g of RbF raw material are uniformly mixed in agate platinum, and then are put into a quartz crucible which is cleaned in advance. Taking out the quartz crucible from the glove box, and vacuumizing to 10 -3 Pa, sealing the pipe orifice of the quartz crucible by oxyhydrogen flame, thereby achieving the purpose of isolating water and oxygen. The crucible is placed in an upper temperature zone of a two-stage temperature-controlled temperature-reducing furnace, the temperature of the upper temperature zone is increased to 880 ℃ at the heating rate of 50 ℃/h, the temperature of the lower temperature zone is increased to 770 ℃ at the heating rate of 50 ℃/h, and the temperature is kept for 24 hours, so that the raw materials in the crucible are completely melted. Then, the quartz crucible was lowered at a lowering speed of 0.7mm/h, and the crystal was grown downward. And continuing to descend until the quartz crucible completely enters a lower temperature zone, ending the crystal growth, and stopping descending. Then the upper temperature area is cooled to the room temperature at the cooling rate of 40 ℃/h, the lower temperature area is cooled to the room temperature at the cooling rate of 50 ℃/h, and the lanthanum bromide scintillation crystal in the quartz crucible is taken out. The obtained lanthanum bromide scintillation crystal is complete and has no cracking, and the energy resolution is 2.5 percent@662 keV.
Example 5
Ce 0.06 Cs 0.002 La 0.938 F 0.002 Br 2.998 Preparation of crystals
Accurately weighing anhydrous and 99-purity in a glove box with water content less than or equal to 0.1ppm and oxygen content less than or equal to 0.1ppm99% of LaBr with oxygen content less than or equal to 100ppm 3 400 g of raw material CeBr 3 26.8 g of raw material and 0.36 g of CsF raw material are uniformly mixed in agate and platinum, and then are put into a quartz crucible which is cleaned in advance. Taking out the quartz crucible from the glove box, and vacuumizing to 10 -4 Pa, sealing the pipe orifice of the quartz crucible by oxyhydrogen flame, thereby achieving the purpose of isolating water and oxygen. The crucible is placed in an upper temperature zone of a two-stage temperature-control dropping furnace, the temperature of the upper temperature zone is increased to 900 ℃ at the heating rate of 30 ℃/h, the temperature of the lower temperature zone is increased to 760 ℃ at the heating rate of 25 ℃/h, and the temperature is kept for 24 hours, so that the raw materials in the crucible are completely melted. Then, the quartz crucible was lowered at a lowering speed of 0.8mm/h, and the crystal was grown downward. And continuing to descend until the quartz crucible completely enters a lower temperature zone, ending the crystal growth, and stopping descending. Then the upper temperature area is cooled to the room temperature at the cooling rate of 15 ℃/h, the lower temperature area is cooled to the room temperature at the cooling rate of 15 ℃/h, and the lanthanum bromide scintillation crystal in the quartz crucible is taken out. The obtained lanthanum bromide scintillation crystal is complete and has no cracking, and the energy resolution is 2.5 percent@662 keV.
Example 6
Ce 0.04 Na 0.001 K 0.002 La 0.957 F 0.003 Br 2.997 Preparation of crystals
In a glove box with the water content less than or equal to 0.1ppm and the oxygen content less than or equal to 0.1ppm, accurately weighing the LaBr with the anhydrous purity of 99.99 percent and the oxygen content less than or equal to 100ppm 3 300 g of raw material CeBr 3 12.6 g of raw material, 0.03 g of NaF raw material and 0.09 g of KF raw material are uniformly mixed in agate platinum, and then are put into a quartz crucible which is cleaned in advance. Taking out the quartz crucible from the glove box, and vacuumizing to 10 -5 Pa, sealing the pipe orifice of the quartz crucible by oxyhydrogen flame, thereby achieving the purpose of isolating water and oxygen. The crucible is placed in an upper temperature zone of a two-stage temperature-controlled temperature-reducing furnace, the temperature of the upper temperature zone is raised to 880 ℃ at the temperature rising rate of 30 ℃/h, the temperature of the lower temperature zone is raised to 745 ℃ at the temperature rising rate of 30 ℃/h, and the temperature is kept constant for 10 hours, so that the raw materials in the crucible are completely melted. Then, the quartz crucible was lowered at a lowering speed of 0.4mm/h, and the crystal was grown downward. Continuously descending until the quartz crucible completely enters a lower temperature zone, and ending the crystal growthThe descent is stopped. Then the upper temperature area is cooled to the room temperature at the cooling rate of 50 ℃/h, the lower temperature area is cooled to the room temperature at the cooling rate of 40 ℃/h, and the lanthanum bromide scintillation crystal in the quartz crucible is taken out. The obtained lanthanum bromide scintillation crystal is complete and has no cracking, and the energy resolution is 2.4% @662keV.
TABLE 1
Note that: "/" indicates the absence of CeBr 3 The doping amount refers to CeBr 3 The molar content of Ce element in 1mol of lanthanum bromide scintillation crystal, and the MF doping amount refers to the molar content of M element in MF in 1mol of lanthanum bromide scintillation crystal.
FIG. 1 shows Ce grown in example 1 0.05 Li 0.004 La 0.946 F 0.004 Br 2.996 As can be seen from fig. 1, the doping of MF effectively suppresses cracking during crystal growth by pinning dislocation, and a complete, cracking-free lanthanum bromide scintillation crystal is obtained. As can be seen from Table 1, example 6 and comparative example 1 use LaBr of the same mass 3 The raw materials can obtain the lanthanum bromide scintillation crystal with equivalent quality, and the energy resolution of the lanthanum bromide scintillation crystal obtained in the embodiment is higher, so that the description shows that under the condition that the quality of the lanthanum bromide scintillation crystal is equivalent, the integrity of the crystal is not obviously affected after the MF is doped. LaBr in examples 2 to 5 3 The quality of the raw materials is higher than that of comparative example 1, that is, the quality of the crystals in examples 2 to 5 is higher, and referring to table 1, the energy resolution of the lanthanum bromide scintillation crystals obtained in examples 2 to 5 is higher, so that it is shown that the integrity of the crystals is not obviously affected after the doping of MF in the case of the lanthanum bromide scintillation crystals with higher quality. The inventors speculate that this is mainly due to M + For Ce 3+ Partial substitution of the lattice site to cause Br in the crystal - The concentration is greatly increased, thus the Auger quenching of free carriers is reduced, and the energy resolution of the obtained lanthanum bromide scintillation crystal is less than 2.6% @662keV. Specifically, FIG. 2 is a diagram of Ce-LaBr in example 1 3 The pulse height spectrogram of the scintillation crystal has the energy resolution of 2.5 percent@662 keV, which is smaller than that of the existing undoped lanthanum bromide scintillation crystal, and the lanthanum bromide scintillation crystal provided by the application has higher energy resolution and excellent performance.
The foregoing description is only of the preferred embodiments of the present application and is not intended to limit the scope of the present application. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application are included in the protection scope of the present application.
Claims (6)
1. A method for growing a lanthanum bromide scintillation crystal, comprising the steps of:
(1) Weigh LaBr 3 、CeBr 3 Mixing with MF solid, and loading into quartz crucible; wherein the LaBr 3 、CeBr 3 And the purity of MF solid is above 99.99%;
(2) Vacuumizing the quartz crucible and sealing;
(3) Heating the sealed quartz crucible in an upper temperature zone of a two-stage temperature-control dropping furnace, keeping constant temperature until the raw materials in the crucible are completely melted after the temperature is raised, and starting a down-leading device to enable the quartz crucible to move from the upper temperature zone to a lower temperature zone for down-leading growth;
(4) Cooling to room temperature to obtain the lanthanum bromide scintillation crystal;
wherein the MF is selected from at least one of LiF, naF, KF, rbF, csF; the structural formula of the lanthanum bromide scintillation crystal is Ce x M y La (1-x-y) F y Br 3-y Wherein x is more than or equal to 0.005 and less than or equal to 0.2, and y is more than 0 and less than or equal to 0.01.
2. The growth method according to claim 1, wherein the upper temperature zone temperature of the descent furnace is 820 ℃ to 900 ℃ and the lower temperature zone temperature is 710 ℃ to 780 ℃.
3. The growth method according to claim 1, wherein the constant temperature time is 8-24 h.
4. The growth method according to claim 1, wherein the downward growth rate is 0.2mm/h-0.8mm/h.
5. The growth method according to claim 1, wherein the upper temperature zone temperature rising rate of the descent furnace is 20 ℃/h-50 ℃/h, the lower temperature zone temperature rising rate is 20 ℃/h-50 ℃/h, the upper temperature zone temperature lowering rate is 15 ℃/h-50 ℃/h, and the lower temperature zone temperature lowering rate is 15 ℃/h-50 ℃/h.
6. A lanthanum bromide scintillation crystal grown according to the growth method of any one of claims 1 to 5 having an energy resolution of less than 2.6% @662keV.
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