CN1526858A - Prepn of flash aluminate crystal doped with trivalent cerium ion - Google Patents
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Abstract
The preparation of flash aluminate crystal doped with trivalent cerium ion features the doping of trivalent cerium compound into the material for growing aluminate crystal; the material sintering in neutral atmosphere; and the pulling process of growing crystal in neutral atmosphere inside MF inducing heating monocrystal furnace. The present invention reduces the introduction of four-valent cerium ion, lowers the quenching effect to luminescent three-valent cerium ion, and raised flash performance of aluminate crystal.
Description
The technical field is as follows:
the invention relates to an aluminate scintillation crystal, in particular to a preparation method of an aluminate scintillation crystal doped with trivalent cerium ions, and specifically relates to a preparation method of a trivalent cerium ion-doped yttrium aluminate, lutetium aluminate, gadolinium aluminate, lutetium yttrium aluminate, lutetium gadolinium aluminate and yttrium gadolinium aluminate scintillation crystal.
Background art:
Ce3+the ion-doped aluminate single crystal is a high-temperature inorganic scintillating material with excellent performance, and has wide application background in the fields of image nuclear medicine (PET) diagnosis, industrial online nondestructive detection, oil well survey, safety inspection, high-energy particle detection and the like.
1973, American scientist M.J.Weber first reported Ce: YAlO3Optical spectral properties of crystals (M.J.Weber, "Optical spectra of Ce3+and Ce3+-sensitizedfluorescence in YAlO3"published in J.appl.Phys., 7 th, volume 44, 3025 th-3028 1973), followed by reports by Japanese scientist Takeda et al on the excellent scintillation characteristics of Ce: YAP materials (Takeda et al, published in J.Electrochem.Soc., 127 th, 438 th 1980). In order to increase the density of the Ce: YAP crystal, heavy elements Lu and Gd are used for replacing Y, so scintillation single crystals such as Ce: LuAP, Ce: GdAP and the like are developed. In 1995, scientists W.W.Moses et al used Czochralski method for the first time to grow and tested the scintillation characteristics of the Ce: LuAP crystal (W.W.Moses, "LuAlO)3: ce a high density, high speed speech for gamma detection "published in IEEE trans. Nucl. Sci., No. 42, 1995, page 275). In recent years, hybrid aluminate scintillation single crystals (J.Chval, et al, "Development of new mixed Lu) have been developed to improve the performance of scintillation crystalsx(RE3+)1-xAP:Ce scintillators(RE3+=Y3+or Gd3+): the composition with other ce-doped or intrinsic cultivation crystals is published inNuclear. instr. meth. in phys. res.a, volume 443, page 331-.
In Ce ion doped rare earth aluminate scintillation crystals, Ce4+Ion pair Ce3+The luminescence center has a severe quenching effect, which greatly affects the scintillation properties of the crystal (E.G. Gumanskaya, "Spectrosco)pic properties and scitillation efficiency ofcerium-doped YAlO3single crystals "published in opt. spectrum, 2 nd, volume 72, p.215 1992). Therefore, how to effectively reduce Ce in the crystal4+The concentration of ions is an important factor in increasing the scintillation efficiency of the crystal.
In the prior art, the Growth of Ce-doped rare earth aluminate scintillation crystals uses solid-phase reaction to generate polycrystalline material as the starting material for crystal Growth (see the prior art, handbook of artificial crystals, 31(2), 2002, p.85-89; Crystal t.Res.Technol.33(2), 1998, p.241 and J.Crystal Growth 198/199, (1999), p.492-496). The polycrystalline raw material is the corresponding high-purity oxide raw material Y2O3(Lu2O3,Gd2O3),Al2O3And CeO2Synthesized at high temperature. The disadvantages of this method are: since the Ce is doped by CeO2Introduced and Ce4+Radius of (2) compared with Ce3+And Y, and3+,Gd3+,Lu3+the fourth-order ionization energy of Ce element is lowest in lanthanide rareearth elements, so that the grown crystal necessarily contains a large amount of Ce4+Ion, to Ce3+The luminescence of (a) produces a severe quenching effect, thereby reducing the scintillation properties of the aluminate crystals.
Disclosure of Invention
The technical problem to be solved by the invention is to overcome the defects of the prior art and provide a method for preparing aluminate scintillation crystal doped with trivalent cerium ions, which solves the problem that CeO is adopted2As a dopant raw material, a large amount of Ce is introduced into aluminate crystals4+Thereby causing a problem of degrading the scintillation performance of the crystal.
The technical solution of the invention is as follows:
a preparation method of trivalent cerium ion doped aluminate scintillation crystal is characterized by comprising the following steps:
doping a compound of trivalent cerium in the formulation of the starting material for the growth of aluminate crystals;
sintering the raw material in a neutral atmosphere;
and growing the crystal by a Czochralski method in a medium-frequency induction heating single crystal furnace in a neutral atmosphere.
The trivalent ion doped aluminate scintillation crystal comprises trivalent cerium ion doped yttrium aluminate, lutetium aluminate, gadolinium aluminate, lutetium yttrium aluminate, lutetium gadolinium aluminate and yttrium gadolinium aluminate scintillation crystal, and the reaction equation under the condition of neutral atmosphere is as follows:
in the formula: x is more than or equal to 0.2% and less than or equal to 3.0%;
0≤y≤1-x;
a and B are Y, Lu or Y, Gd or Lu and Gd respectively.
The compound of trivalent cerium is Ce (OH)3、Ce2(C2O4)3、Ce(CH3COO)3Or Ce2(CO3)3The reaction equations of the compounds under neutral atmosphere conditions are respectively as follows:
the invention relates to a preparation method of a trivalent cerium ion doped aluminate scintillation crystal, which comprises the following specific preparation steps:
1. according to the reaction equation, selecting x, y, A and B, and weighing the raw materials according to the corresponding mole percentage;
2. mechanically mixing the raw materials uniformly, and pressing at 20-40kg/cm with a pressing machine2Pressing the mixture into a cake;
3. sintering the material cake at 1000-1600 ℃ for 10-20 hours in a neutral atmosphere to form a sintered cake;
4. putting the sintered cake into a medium-frequency induction heating single crystal furnace, vacuumizing, and filling high-purity nitrogen;
5. heating and melting to grow crystals, wherein the growth conditions are as follows: the pulling speed is 1-3mm/h, andthe rotating speed is 10-20 rpm;
6. after the crystal grows, slowly cooling to room temperature, and taking out the crystal.
In the ④ step, high-purity argon gas can be filled.
The device for growing the cerium-doped aluminate scintillation crystal by the Czochralski method is a common intermediate-frequency induction heating single crystal furnace. The device comprises an iridium crucible, a vacuum system, a power supply of a medium-frequency induction generator, a temperature control system and the like.
The invention has the advantages that: due to the adoption of Ce2(CO3)3By substituting CeO with compounds containing trivalent cerium2As the doping raw material and the growing crystal which are pre-sintered and uniformly mixed in the neutral atmosphere are adopted, the Ce can be reduced to a great extent4+Reduction of Ce3+The quenching effect of luminescence can improve the scintillation property of aluminate crystal by 5-15%.
Detailed Description
The present invention is further illustrated by the following examples, which should not be construed as limiting the scope of the invention.
Example 1.
With Ce2(CO3)3As a dopant raw material, yttrium aluminate scintillation crystal is grown.
Under neutral atmosphere conditions, the chemical reaction equation in this example is:
where X is 0.2%
So that Y is2O3,Al2O3,Ce2(CO3)3The high-purity raw materials are mixed according to the mol ratio of 0.998: 1: 0.002The total weight is 1 Kg. Mechanically mixing, and pressing at 40kg/cm2Pressing into a cake under the pressure of the pressure, sintering for 20 hours at 1600 ℃ in a neutral nitrogen atmosphere, filling high-purity nitrogen into the furnace in a vacuum manner, and heating and melting to prepare for growth. The pulling rate was 3mm/h and the rotation speed was 20 rpm.After the crystal grows, slowly cooling to room temperature, and taking out the crystal. The crystal is colorless, transparent and complete, and has good quality. The light output scintillation property is tested and compared with CeO2The yttrium aluminate scintillation crystal with the same concentration as the dopant raw material is obviously improved.
Example 2.
With Ce (OH)3As a dopant raw material, yttrium aluminate scintillation crystal is grown.
Under neutral atmosphere conditions, the chemical reaction equation in this example is:
where X is 3.0%
So that Y is2O3,Al2O3,Ce(OH)3The high-purity raw materials are weighed according to the molar ratio of 0.97: 1: 0.06, and the total weight is 1 Kg. Mechanically mixing, and pressing at 20kg/cm2Pressing into a cake under the pressure of the pressure, sintering for 10 hours at 1000 ℃ in a neutral nitrogen atmosphere, filling high-purity nitrogen into the furnace in a vacuum manner, and heating andmelting to prepare for growth. The pulling rate was 1mm/h and the rotation speed was 10 rpm. After the crystal grows, slowly cooling to room temperature, and taking out the crystal. The crystal is colorless, transparent and complete, and has good quality. The light output scintillation property is tested and compared with CeO2The yttrium aluminate scintillation crystal with the same concentration as the dopant raw material is obviously improved.
Example 3
With Ce2(C2O4)3As a dopant raw material, yttrium aluminate scintillation crystal is grown.
Under neutral atmosphere conditions, the chemical reaction equation in this example is:
where X is 1.0%
So that Y is2O3,Al2O3,Ce2(C2O4)3The high-purity raw materials are weighed according to the molar ratio of 0.99: 1: 0.01, and the total weight is 1 Kg. Mechanically mixing, and pressing at 30kg/cm2Pressing into cake under pressure, sintering at 1400 deg.C for 15 hr in neutral nitrogen atmosphere, charging into furnace, and vacuumizingFilling high-purity nitrogen in the air, and heating and melting to prepare for growth. The pulling rate was 2mm/h and the rotation speed was 15 rpm. After the crystal grows, slowly cooling to room temperature, and taking out the crystal. The crystal is colorless, transparent and complete, and has good quality. The light output scintillation property is tested and compared with CeO2The yttrium aluminate scintillation crystal with the same concentration as the dopant raw material is obviously improved.
Example 4
With Ce (CH)3COO)3As a dopant raw material, yttrium aluminate scintillation crystal is grown.
Under neutral atmosphere conditions, the chemical reaction equation in this example is:
where X is 0.6%
So that Y is2O3,Al2O3,Ce(CH3COO)3The high-purity raw materials are weighed according to the molar ratio of 0.994: 1: 0.012, and the total weight is 1 Kg. Mechanically mixing, and pressing at 35kg/cm2Pressing into a cake under the pressure of the pressure, sintering for 18 hours at 1300 ℃ in a neutral nitrogen atmosphere, filling high-purity nitrogen into the furnace in a vacuum manner, and heating and melting to prepare for growth. The pulling rate was 2mm/h and the rotation speed was 12 rpm. After the crystal grows, slowly cooling to room temperature, and taking out the crystal. The crystal is colorless, transparent and complete, and has good quality. The light output scintillation property is tested and compared with CeO2The yttrium aluminate scintillation crystal with the same concentration as the dopant raw material is obviously improved.
Example 5
With Ce2(CO3)3As a dopant raw material, growing lutetium yttrium aluminate scintillation crystal.
Under neutral atmosphere conditions, the chemical reaction equation in this example is:
where X is 1.0% and y is 0.3
So that Y is2O3,Lu2O3,Al2O3,Ce2(CO3)3The high-purity raw materials are weighed according to the molar ratio of 0.69: 0.3: 1: 0.01, and the total weight is 1 Kg. After being mechanically mixed evenly, the mixture is pressed by a pressing machine25kg/cm2Pressing into a cake under the pressure of the pressure, sintering for 16 hours at 1400 ℃ in a neutral nitrogen atmosphere, filling high-purity nitrogen into the furnace in a vacuum manner, and heating and melting to prepare for growth. The pulling rate was 2mm/h and the rotation speed was 14 rpm. After the crystal grows, slowly cooling to room temperature, and taking out the crystal. The crystal is colorless, transparent and complete, and has good quality. The light output scintillation property is tested and compared with CeO2The lutetium yttrium aluminate scintillation crystal with the same concentration as the dopant raw material is obviously improved.
Example 6
With Ce2(CO3)3As a dopant raw material, growing yttrium gadolinium aluminate scintillation crystal.
Under the condition of neutral atmosphere, the chemical reaction equation in this example is:
where X is 1.2% and y is 0.2
So that Y is2O3,Gd2O3,Al2O3,Ce2(CO3)3The high-purity raw materials are weighed according to the molar ratio of 0.788: 0.2: 1: 0.012, and the total weight is 1 Kg. Mechanically mixing, and pressing at 35kg/cm2Pressing into a cake under the pressure of the pressure, sintering for 14 hours at 1500 ℃ in a neutral nitrogen atmosphere, filling high-purity nitrogen into the furnace in a vacuum manner, and heating and melting to prepare for growth. The pulling rate was 1.5mm/h and the rotation speed was 13 rpm. After the crystal grows, slowly cooling to room temperature, and taking out the crystal. The crystal is colorless, transparent and complete, and has good quality. The light output scintillation property is tested and compared with CeO2The yttrium gadolinium aluminate scintillation crystal with the same concentration as the dopant raw material is obviously improved.
Example 7.
With Ce2(CO3)3As a dopant raw material, growing lutetium gadolinium aluminate scintillation crystal.
Under neutral atmosphere conditions, the chemical reaction equation in this example is:
where X is 1.6% and y is 0.4
So Lu will be2O3,Gd2O3,Al2O3,Ce2(CO3)3The high-purity raw materials are mixed according to the ratio of 0.584: 0.4: 10.016 in a molar ratio, and the total weight is 1 Kg. Mechanically mixing, and pressing at 35kg/cm2Pressing into a cake under the pressure of the pressure, sintering for 14 hours at 1500 ℃ in a neutral atmosphere, filling high-purity nitrogen into the furnace in a vacuum manner, and heating and melting to prepare for growth. The pulling rate was 1.5mm/h and the rotation speed was 13 rpm. After the crystal grows, slowly cooling to room temperature, and taking out the crystal. The crystal is colorless, transparent and complete, and has good quality. The light output scintillation property is tested and compared with CeO2The yttrium gadolinium aluminate scintillation crystal with the same concentration as the dopant raw material is obviously improved.
Example 8.
With Ce2(CO3)3As a dopant raw material, growing lutetium aluminate scintillation crystal.
Under neutral atmosphere conditions, the chemical reaction equation in this example is:
where X is 0.8%
So Lu will be2O3,Al2O3,Ce2(CO3)3The high-purity raw materials are weighed according to the molar ratio of 0.992: 1: 0.008, and the total weight is 1 Kg. Mechanically mixing, and pressing at 30kg/cm2Pressing into cakes under the pressure of the pressure, sintering for 20 hours at 1450 ℃ in a neutral atmosphere, filling high-purity nitrogen into the furnace in a vacuumizing way, and heating and melting to prepare for growth. The pulling rate was 1mm/h, and the rotation speed was 12 rpm. After the crystal grows, slowly cooling to room temperature, and taking out the crystal. The crystal is colorless, transparent and complete, and has good quality. The light output scintillation property is tested and compared with CeO2The lutetium aluminate scintillation crystal with the same concentration as the dopant raw material is obviously improved.
Example 9.
With Ce2(CO3)3As a dopant raw material, growing gadolinium aluminate scintillation crystal.
Under neutral atmosphere conditions, the chemical reaction equation in this example is:
where X is 0.8%
Thus Gd is reacted with2O3,Al2O3,Ce2(CO3)3The high-purity raw materials are weighed according to the molar ratio of 0.992: 1: 0.008, and the total weight is 1 Kg. Mechanically mixing, and pressing at 20kg/cm2Pressing into a cake under the pressure of the pressure, sintering for 20 hours at 1400 ℃ in a neutral atmosphere, filling high-purity nitrogen into the furnace in a vacuum manner, and heating and melting to prepare for growth. The pulling rate is 1mm/h, the rotation speedAt 12 rpm. After the crystal grows, slowly cooling to room temperature, and taking out the crystal. The crystal is colorless, transparent and complete, and has good quality. The light output scintillation property is tested and compared with CeO2The gadolinium aluminate scintillation crystal with the same concentration as the dopant raw material is obviously improved.
Tests show that the scintillation property of the crystal is improved by 5-15% in all the embodiments.
Claims (5)
1. A preparation method of trivalent cerium ion doped aluminate scintillation crystal is characterized by comprising the following steps:
① trivalent cerium compound is doped in the raw material formula for growing aluminate crystal;
② sintering the raw materials in a neutral atmosphere;
③ under neutral atmosphere, crystal is grown by Czochralski method in a medium frequency induction heating single crystal furnace.
2. The method for preparing the trivalent cerium ion doped aluminate scintillation crystal as claimed in claim 1, wherein the trivalent cerium ion doped aluminate scintillation crystal comprises trivalent cerium ion doped yttrium aluminate, lutetium aluminate, gadolinium aluminate, lutetium yttrium aluminate, lutetium gadolinium aluminate and yttrium gadolinium aluminate scintillation crystals, and the reaction equation under the condition of neutral atmosphere is as follows:
in the formula: x is more than or equal to 0.2% and less than or equal to 3.0%;
0≤y≤1-x;
a and B are Y, Lu or Y, Gd or Lu and Gd respectively.
3. The method for preparing cerium (III) ion doped aluminate scintillating crystal according to claim 2, wherein the compound of cerium (III) is Ce (OH)3、Ce2(C2O4)3、Ce(CH3COO)3Or Ce2(CO3)3The reaction equations of the compounds under neutral atmosphere conditions are respectively as follows:
4. the method for preparing the cerium (III) ion doped aluminate scintillation crystal according to claim 3, which is characterized by comprising the following steps:
① selecting x, y, A and B according to the above equation, and weighing the raw materials according to the corresponding molar percentages;
② mixing the raw materials mechanically, pressing with a pressing machine at 20-40kg/cm2Pressing under pressure ofForming a material cake;
③ sintering at 1000-1600 deg.C for 10-20 h in neutral atmosphere to form sintered cake;
④ placing the sintered cake into a medium frequency induction heating single crystal furnace, vacuumizing, and charging high purity nitrogen;
⑤ heating to melt and growing crystal, wherein the pulling speed is 1-3mm/h and the rotating speed is 10-20 rpm;
⑥ after growing the crystal, slowly cooling to room temperature, and taking out the crystal.
5. The method for preparing cerium (III) ion doped aluminate scintillating crystals according to claim 4, wherein high purity argon gas can be introduced into the ④ step.
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Cited By (2)
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CN106319635A (en) * | 2016-09-30 | 2017-01-11 | 中国电子科技集团公司第二十六研究所 | Method for enhancing light output of cerium-doped lutetium yttrium aluminate (LuYAP) scintillation crystals |
CN108330541A (en) * | 2018-01-19 | 2018-07-27 | 暨南大学 | A kind of GYAP laser crystals and preparation method thereof |
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CN106319635A (en) * | 2016-09-30 | 2017-01-11 | 中国电子科技集团公司第二十六研究所 | Method for enhancing light output of cerium-doped lutetium yttrium aluminate (LuYAP) scintillation crystals |
CN108330541A (en) * | 2018-01-19 | 2018-07-27 | 暨南大学 | A kind of GYAP laser crystals and preparation method thereof |
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