Cerium-doped gadolinium gallium aluminum garnet polycrystal and preparation method thereof

Abstract

The chemical formula of the cerium-doped gadolinium gallium aluminum garnet polycrystal is Cex: Gd3 (1-x) (Aly, Ga (1-y)) 5O12, the preparation method comprises the following steps of: preparing Cex: Gd3 (1-x) (Aly, Ga (1-y)) 5O12 according to mole fraction; the ratio of (Gd + Ce) to Al + Ga is 3: 5; the cerium-doped gadolinium gallium aluminum garnet polycrystal is synthesized at low temperature by adopting a citric acid combustion method, the powder purity is high, the powder morphology is regular and uniform, the powder particles are small, the dispersity is good, the agglomeration degree is low, and the preparation efficiency of a combustion method preparation technology is higher than that of a sol-gel method; the high-temperature decomposition of Ga2O3 in the traditional preparation process is avoided, the crystal quality is improved, and the production cost is reduced; compared with the prior art, all reactants can be mixed more uniformly, the chemical combination reaction is more sufficient, unreacted Ga2O3 does not exist, and the cerium-doped gadolinium gallium aluminum garnet polycrystal with high purity can be obtained.

Description

Technical Field

[0001] The embodiments of the present invention relate to a polycrystal and a preparation method thereof, and in particular to a cerium-doped gadolinium gallium aluminum garnet polycrystal and a preparation method thereof. Background Art

[0002] Ce:GAGG is a cerium-doped gadolinium-gallium aluminum garnet. 3 (Al,Ga) 5 O 12 It is the oxide scintillator crystal with the highest light yield in the world, with a light yield of up to 75,000 photons / MeV, which is three times that of cerium-doped yttrium-lutetium silicate crystals. The optimal energy resolution can reach 3.7% (@662KeV), which is 7% better than Ce:LYSO crystal (@662KeV). In addition, Ce:GAGG crystals have no deliquescence and self-radiation problems, and have very broad application prospects in medical imaging, high-energy physics, nuclear physics and other fields.

[0003] The traditional Ce:GAGG crystal growth process uses high-purity Gd 2 O 3 、Al 2 O 3 , Ga 2 O 3 and CeO 2 The powders are mixed evenly in a certain ratio, and then pressed into a cylindrical shape by isostatic pressing. Ce:GAGG polycrystalline raw materials are synthesized at 1300℃ in a high-temperature muffle furnace, and then crystals are grown by the pulling method to prepare Ce:GAGG single crystals. 2 O 3 It is easy to decompose at high temperature, so the Ce:GAGG polycrystalline powder prepared by high temperature synthesis will have component deviation, thus affecting the crystal quality; at the same time, during the crystal growth process, Ga 2 O 3 The decomposition produces oxygen, which causes oxidation of the iridium crucible used to grow the crystal, increasing production costs. Summary of the invention

[0004] The purpose of the embodiments of the present invention is to provide a cerium-doped gadolinium gallium aluminum garnet polycrystal with high powder purity, regular and uniform powder morphology, small powder particles, good dispersibility, low agglomeration degree, combustion preparation technology, and a preparation efficiency higher than that of the sol-gel method and a preparation method thereof.

[0005] The present invention provides a cerium-doped gadolinium gallium aluminum garnet polycrystal, comprising:

[0006] The chemical formula of the cerium-doped gadolinium gallium aluminum garnet polycrystalline is: Ce x :Gd 3(1-x) (Aly ,Ga (1-y) ) 5 O 12 ; wherein, in the Ce x :Gd 3(1-x) (Al y ,Ga (1-y) ) 5 O 12 According to the molar fraction;

[0007] (Gd+Ce):(Al+Ga)=3:5.

[0008] Further, in the cerium-doped gadolinium gallium aluminum garnet polycrystal of the present invention, the unreacted Ga 2 O 3 The content is 0 in terms of molar fraction.

[0009] Furthermore, in the cerium-doped gadolinium gallium aluminum garnet polycrystal of the present invention, the range of x in the cerium-doped gadolinium gallium aluminum garnet polycrystal is 0.001 to 0.05, and the range of y is 0 to 0.8.

[0010] The present invention also provides a method for preparing cerium-doped gadolinium gallium aluminum garnet polycrystals, comprising the following steps:

[0011] Step S1: Gd 2 O 3 、Al 2 O 3 , Ga 2 O 3 and CeO 2 as a raw material, dissolving it by reacting with nitric acid to prepare a nitrate solution; proceeding to step S2;

[0012] Step S2: the nitrate solution in step S1 is prepared into a mixed solution according to the molar ratio of (Gd+Ce):(Al+Ga)=3:5, citric acid is added to the mixed solution, the molar fraction of the citric acid is 1.5 times the total molar number of Gd, Ga and Ce ions, and stirred in a water bath at a constant temperature of 80° C. on a magnetic stirrer until all dissolved; then proceed to step S3;

[0013] Step S3: Then add dispersant polyethylene glycol in an amount of 1 / 10 of the mass of the nitric acid, stir in a water bath at a constant temperature of 80° C. on a magnetic stirrer until all dissolved; obtain a mixed solution, and proceed to step S4;

[0014] Step S4: slowly dripping ammonia water into the mixed solution in step S3 until the pH value reaches 7, and continuously stirring in a magnetic stirrer while heating until the mixture is completely evaporated to form a gel, and then closing the mixture and cooling to room temperature; proceeding to step S5;

[0015] Step S5: placing the gel obtained in step S4 in an oven and heating it to 280° C. for 4 hours until the citric acid is completely burned to obtain a fluffy precursor powder; proceeding to step S6;

[0016] Step S6: isostatically pressing the precursor powder obtained in step S5 into a suitable cylindrical shape, placing it in a muffle furnace and heating it to 900° C. for 10 hours to synthesize the cerium-doped gadolinium gallium aluminum garnet polycrystal.

[0017] In order to achieve the above-mentioned purpose, the embodiment of the present invention is compared with the prior art. The chemical formula of the cerium-doped gadolinium gallium aluminum garnet polycrystalline in the present invention is: Ce x :Gd 3(1-x) (Al y ,Ga (1-y) ) 5 O 12 Among them, in Ce x :Gd 3(1-x) (Al y ,Ga (1-y) ) 5 O 12 According to the molar fraction; (Gd+Ce):(Al+Ga)=3:5; Ce-doped gadolinium gallium aluminum garnet polycrystals were synthesized at low temperature by citric acid combustion method,

[0018] In view of these problems, the present invention discloses a method for preparing cerium-doped gadolinium gallium aluminum garnet polycrystals, wherein a citric acid combustion method is used to synthesize Ce:GAGG raw materials at low temperature. The polycrystals synthesized by this method have the following advantages: high powder purity, regular and uniform powder morphology, small powder particles, good dispersibility, low agglomeration degree, and a combustion method preparation technology with a higher preparation efficiency than a sol-gel method; the citric acid combustion method is used to synthesize Ce:GAGG raw materials at low temperature, which can avoid the Ga in the traditional preparation process. 2 O 3 High temperature decomposition, thereby improving the quality of Ce:GAGG crystals and reducing production costs; the synthesis process temperature of Ce:GAGG polycrystalline raw materials obtained by this method is low, and Ga 2 O 3 Almost no decomposition.

[0019] The cerium-doped gadolinium gallium aluminum garnet polycrystal obtained by the method can mix the reactants more evenly, the chemical reaction is more complete, and there is no unreacted Ga 2 O 3 , high-purity Ce-doped Gd-Ga-A-Garnet polycrystals can be obtained;

[0020] The cerium-doped gadolinium gallium aluminum garnet polycrystalline powder obtained by the method has regular and uniform pure morphology, small powder particles, good dispersibility and low agglomeration degree; the cerium-doped gadolinium gallium aluminum garnet polycrystalline obtained by the method has high preparation efficiency, and the cerium-doped gadolinium gallium aluminum garnet scintillation crystals grown by using the raw materials prepared in this way are of better quality and consistency. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 The present invention is a flow chart of the preparation method of the cerium-doped gadolinium gallium aluminum garnet polycrystal. DETAILED DESCRIPTION

[0022] In order to make the purpose, technical scheme and advantages of the present invention clearer, the following will be described in detail with reference to the accompanying drawings. However, it will be appreciated by those skilled in the art that in the various embodiments of the present invention, many technical details are provided in order to enable the reader to better understand the present application. However, even without these technical details and various changes and modifications based on the following embodiments, the technical scheme claimed for protection in the claims of the present application can be implemented.

[0023] The present invention provides 3 embodiments, such as Figure 1 As shown, the specific embodiments are as follows:

[0024] Example 1: Ce-doped polycrystalline Gadolinium gallium aluminum garnet with a concentration of 1%, molecular formula Ce 0.03 :Gd 3(1-0.01) (Al 2 ,Ga 3 ) 5 O 12 Preparation of

[0025] S1: Take 1.485 mol, or 538.3 grams of Gd 2 O 3 Take 0.03molCeO 2 That is 5.2 grams, dissolved in 9 mol of nitric acid to form a solution, take 1.5 mol, that is 281.2 grams of Ga 2 O 3 Take 1 mol, which is 101.9 grams of Al 2 O 3 Dissolve in 15 mol nitric acid to form a solution.

[0026] S2: Mix the above nitrate solutions and add 36 mol of citric acid, stir in a water bath at 80°C on a magnetic stirrer until all the nitrate solutions are dissolved.

[0027] S3: Then add 2400 g of polyethylene glycol as a dispersant and stir in a water bath at 80°C on a magnetic stirrer until all the mixture is dissolved.

[0028] S4: Slowly drop ammonia water into the mixed solution until the pH value reaches 7, and keep stirring in a magnetic stirrer while heating until the solution evaporates completely to form a gel, then turn off the addition and cool to room temperature.

[0029] S5: Place the gel in an oven and heat to 280°C for 4 hours until the citric acid is completely burned to obtain a fluffy precursor powder.

[0030] S6: The precursor powder is isostatically pressed into a suitable cylindrical shape, and then placed in a muffle furnace and heated to 900°C for 10 hours to synthesize a polycrystalline gadolinium gallium aluminum garnet with a cerium concentration of 1%, and the molecular formula is Ce 0.03 :Gd 3(1-0.01) (Al 2 ,Ga 3 ) 5 O 12 .

[0031] Example 2: Gd-Ga-A-G polycrystalline with a Ce-doped concentration of 2%, molecular formula Ce 0.06 :Gd 3(1-0.02) (Al 2 ,Ga 3 ) 5 O 12 Preparation.

[0032] S1: Take 1.47 mol, or 532.9 grams of Gd 2 O 3 ; Take 0.06molCeO 2 That is, 10.4 grams, dissolved in 9 mol of nitric acid to form a solution, take 1.5 mol, that is, 281.2 grams of Ga 2 O 3 Take 1 mol, which is 101.9 grams of Al 2 O3 is dissolved in 15 mol nitric acid to form a solution.

[0033] S2: Mix the above nitrate solutions and add 36 mol of citric acid, stir in a water bath at 80°C on a magnetic stirrer until all the nitrate solutions are dissolved.

[0034] S3: Then add 2400 g of polyethylene glycol as a dispersant and stir in a water bath at 80°C on a magnetic stirrer until all the mixture is dissolved.

[0035] S4: Slowly drop ammonia water into the mixed solution until the pH value reaches 7, and keep stirring in a magnetic stirrer while heating until the solution evaporates completely to form a gel, then turn off the addition and cool to room temperature.

[0036] S5: Place the gel in an oven and heat to 280°C for 4 hours until the citric acid is completely burned to obtain a fluffy precursor powder.

[0037] S6: The precursor powder is isostatically pressed into a suitable cylindrical shape, and then placed in a muffle furnace and heated to 900°C for 10 hours to synthesize a polycrystalline gadolinium gallium aluminum garnet with a cerium concentration of 2% and a molecular formula of Ce. 0.06 :Gd 3(1-0.02) (Al 2 ,Ga 3 ) 5 O 12 .

[0038] Example 3: Ce-doped polycrystalline Gadolinium gallium aluminum garnet with a concentration of 1%, molecular formula Ce 0.06 :Gd 3(1-0.02) (Al 2 ,Ga 3 ) 5 O 12 Preparation of

[0039] S1: Take 1.47 mol, or 532.9 grams of Gd 2 O 3 Take 0.06molCeO 2 That is, 10.4 grams, dissolved in 9 mol of nitric acid to form a solution, take 1 mol, that is, 187.4 grams of Ga 2 O 3 Take 1.5 mol, or 152.9 grams of Al 2 O 3 Dissolve in 15 mol nitric acid to form a solution.

[0040] S2: Mix the above nitrate solutions and add 36 mol of citric acid, stir in a water bath at 80°C on a magnetic stirrer until all the nitrate solutions are dissolved.

[0041] S3: Then add 2400 g of polyethylene glycol as a dispersant and stir in a water bath at 80°C on a magnetic stirrer until all the mixture is dissolved.

[0042] S4: Slowly drop ammonia water into the mixed solution until the pH value reaches 7, and keep stirring in a magnetic stirrer while heating until the solution evaporates completely to form a gel, then turn off the addition and cool to room temperature.

[0043] S5: Place the gel in an oven and heat to 280°C for 4 hours until the citric acid is completely burned to obtain a fluffy precursor powder.

[0044] S6: The precursor powder is isostatically pressed into a suitable cylindrical shape, and then placed in a muffle furnace and heated to 900°C for 10 hours to synthesize a polycrystalline gadolinium gallium aluminum garnet with a cerium concentration of 1%, and the molecular formula is Ce 0.06 :Gd 3(1-0.02) (Al 2 ,Ga 3 )5 O 12 .

[0045] The Ce-doped Gd-Ga-AG polycrystals obtained in the above three embodiments have been tested to contain no unreacted Ga 2 O 3 The obtained cerium-doped gadolinium gallium aluminum garnet polycrystals have high purity, regular and uniform polycrystal powder morphology, small powder particles, good dispersibility and low agglomeration degree; the preparation efficiency of the cerium-doped gadolinium gallium aluminum garnet polycrystals obtained by this method is high, and the cerium-doped gadolinium gallium aluminum garnet scintillation crystals grown by using the raw materials prepared in this way are better in quality and consistency.

[0046] Those skilled in the art will appreciate that the above-mentioned embodiments are specific examples for implementing the present invention, and in actual applications, various changes may be made thereto in form and detail without departing from the spirit and scope of the present invention.

Claims

1. A cerium-doped gadolinium gallium aluminum garnet polycrystal, characterized in that: include: The chemical formula of the cerium-doped gadolinium-gallium-aluminum-garnet polycrystalline is: Ce x :Gd 3(1-x) (Al y ,Ga (1-y) )5O 12 ; Among them, in the Ce x :Gd 3(1-x) (Al y ,Ga (1-y) )5O 12 According to the molar fraction; (Gd+Ce):(Al+Ga)=3:

5.

2. The cerium-doped gadolinium gallium aluminum garnet polycrystalline according to claim 1, characterized in that: The content of unreacted Ga2O in the cerium-doped gadolinium gallium aluminum garnet polycrystal is 0 in terms of molar fraction.

3. The cerium-doped gadolinium gallium aluminum garnet polycrystalline according to claim 1, characterized in that: The range of x in the cerium-doped gadolinium gallium aluminum garnet polycrystal is 0.001-0.05, and the range of y is 0-0.

8.

4. A method for preparing cerium-doped gadolinium gallium aluminum garnet polycrystals, characterized in that: The following steps are involved: Step S1: Gd2O3, Al2O3, Ga2O3 and CeO2 are used as raw materials, and are dissolved by reaction with nitric acid to prepare a nitrate solution; and then proceed to step S2; Step S2: the nitrate solution in step S1 is prepared into a mixed solution according to the molar ratio of (Gd+Ce):(Al+Ga)=3:5, citric acid is added to the mixed solution, the molar fraction of the citric acid is 1.5 times the total molar number of Gd, Ga and Ce ions, and stirred in a water bath at a constant temperature of 80° C. on a magnetic stirrer until all dissolved; then proceed to step S3; Step S3: Then add dispersant polyethylene glycol in an amount of 1 / 10 of the mass of the nitric acid, stir in a water bath at a constant temperature of 80° C. on a magnetic stirrer until all dissolved; obtain a mixed solution, and proceed to step S4; Step S4: slowly dripping ammonia water into the mixed solution in step S3 until the pH value reaches 7, and continuously stirring in a magnetic stirrer while heating until the mixture is completely evaporated to form a gel, and then closing the mixture and cooling to room temperature; proceeding to step S5; Step S5: putting the gel obtained in step S4 into an oven and heating it to 280° C. for 4 hours until the citric acid is completely burned to obtain a fluffy precursor powder; proceeding to step S6; Step S6: isostatically pressing the precursor powder obtained in step S5 into a suitable cylindrical shape, placing it in a muffle furnace and heating it to 900° C. for 10 hours to synthesize the cerium-doped gadolinium gallium aluminum garnet polycrystal.

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