WO2024179025A1

WO2024179025A1 - Cerium-activated rare earth silicate inorganic scintillating material and preparation method therefor

Info

Publication number: WO2024179025A1
Application number: PCT/CN2023/129946
Authority: WO
Inventors: 林利添; 陈鹏允; 杨鸣名; 倪海勇; 张秋红; 姜伟
Original assignee: 广东省科学院资源利用与稀土开发研究所
Priority date: 2023-02-27
Filing date: 2023-11-06
Publication date: 2024-09-06
Also published as: CN116333740B; CN116333740A

Abstract

A cerium-activated rare earth silicate inorganic scintillating material and a preparation method therefor. The expression of the chemical composition of the cerium-activated rare earth silicate inorganic scintillating material is Gd2-x-yLuxSi2O7:Cey, wherein the value ranges of x are 0.2≤x≤0.6 and 1.2≤x≤1.25, and the value range of y is 0.001≤y≤0.05. The cerium-activated rare earth silicate inorganic scintillating material has good radioluminescence intensity under the excitation of high-energy rays, and can be applied to radiation detection and imaging fields such as nuclear logging or nuclear medical imaging.

Description

A cerium-activated rare earth silicate inorganic scintillating material and preparation method thereof

Technical field:

The invention relates to the technical field of rare earth functional materials, and in particular to a cerium-activated rare earth silicate inorganic scintillating material and a preparation method thereof.

Background technology:

Nuclear logging technology is an important means of modern resource exploration. It can accurately classify lithology, measure porosity, and monitor in real time the movement of oil, gas, and water interfaces in formations and changes in remaining oil and gas saturation, providing important support for the country's resource and energy security.

With the gradual depletion of shallow resources, the exploration of deep resources has become increasingly important, because about 20% of the world's resources are distributed in deep strata over 6,000-7,000 meters, and about 30% of my country's resources are distributed in this range, and Tarim may account for more than 60%. The Shunbei Oil and Gas Field Base is located deep in the desert of the Tarim Basin. This base has drilled wells over 9,000 meters deep. Such deep wells place very high demands on nuclear logging technology: that is, the scintillator material must still maintain a high light output at high temperatures (>175°C) to meet the sensitivity requirements. The NaI:Tl crystals that are still commonly used can no longer meet long-term requirements.

Cerium-activated rare earth silicates can meet such stringent requirements, such as orthorhombic phase Gd ₂ Si ₂ O ₇ :Ce ³⁺ . However, due to the non-isotropic melting problem of Gd ₂ Si ₂ O ₇ (as shown in Figure 1), its crystal material cannot be grown by the Czochralski method, but needs to be grown by the molten salt-assisted top seeding method, which faces the problems of difficult growth technology, long cycle and high cost. By co-doping with La ³⁺ to stabilize Gd ₂ Si ₂ O ₇ , triclinic or monoclinic phase (Gd,La) ₂ Si 2 O ₇ :Ce ³⁺ crystals with nearly isotropic melting can be obtained. It is worth noting that co-doping with high concentration of La ³⁺ (>20at%) will reduce the light output and radiant luminescence thermal stability of the original Gd ₂ Si ₂ O ₇ :Ce ³⁺ _. Therefore, this problem needs to be solved urgently.

Summary of the invention:

The present invention solves the problems existing in the prior art and provides a cerium-activated rare earth silicate inorganic scintillating material and a preparation method thereof. The present invention significantly improves the disadvantage of non-isotropic melting of Gd ₂ Si ₂ O ₇ by co-doping Lu ³⁺ in Gd ₂ Si ₂ O ₇ :Ce ³⁺ , and does not significantly reduce the radiation luminescence intensity of the original Gd ₂ Si ₂ O ₇ :Ce ³⁺ . The cerium-activated rare earth silicate scintillating material provided by the present invention has excellent radiation luminescence intensity. This has broadened its application in radiation detection imaging such as nuclear well logging or nuclear medical imaging.

The object of the present invention is to provide a cerium _- activated rare earth silicate inorganic scintillating material, the chemical composition of the material is: _Gd2 _- _xyLuxSi2O7 : _Cey , and the value range of x is 0.2≤x≤0.6 and 1.2≤x≤1.25, and the value range of y is 0.001≤y≤0.05.

The Gd2 _-xyLuxSi2O7 _: _Cey _rare earth scintillating material disclosed in the present invention contains three rare earth elements Gd, Lu and Ce, and the ratio of (Gd+Lu+Ce):Si:O is 2:2:7 _. The value range of x is: 0.2≤x≤0.6 and 1.2≤x≤1.25, and the value range of y is 0.001≤y≤0.05. According to the different content of Lu ³⁺ , the material has different crystal structures, but they are all different from the so-called pyrochlore mineral (Gd,La) _2Si2O7 _published in the _Japanese patent. When the Lu ³⁺ content is 0.2≤x≤0.6, the material has an orthorhombic structure, which is different from the triclinic structure (Gd _0.9 Lu _0.1 ) ₂ Si ₂ O ₇ disclosed in the prior art CN105969354A and Physica B 2017,527,21-23 (similar to the crystal structure of Eu ₂ Si ₂ O ₇ and (Gd,La) ₂ Si ₂ O ₇ ). Co-doping with Lu ³⁺ improves the non-isotropic melting problem of Gd ₂ Si ₂ O ₇ (as shown in FIG2 ), and does not significantly reduce the radiation luminescence intensity of the original Gd ₂ Si ₂ O ₇ :Ce ³⁺ (as shown in FIG3 ), which is very beneficial for obtaining large single crystal materials with excellent performance.

Preferably, when the value range of x is 0.2≤x≤0.6, and the value range of y is 0.001≤y≤0.05, the material has an orthorhombic structure, a space group Pnma, and a unit cell parameter range of: α＝β＝γ＝90°, Density ρ=5.61-5.78 g/cm ³ ; when the value range of x is 1.2≤x≤1.25, and the value range of y is 0.001≤y≤0.05, the material has a monoclinic structure space group P2 ₁ /c, and the range of unit cell parameters is: α=γ=90°, β=137.395～137.370°, Density ρ = 5.99-6.01 g/cm ³ .

Preferably, the value range of x is 0.2≤x≤0.6 and 1.2≤x≤1.25, and the value range of y is 0.001≤y＜0.002.

Preferably, the value range of x is 0.2≤x≤0.6 and 1.2≤x≤1.25, and the value range of y is 0.002＜y≤0.05.

Preferably, when the value range of x is 0.2≤x≤0.6, the value range of y is 0.01≤y≤0.05, and when the value range of x is 1.2≤x≤1.25, the value range of y is 0.01≤y≤0.04.

More preferably, the material is selected from at least one of the following materials: Gd _1.78 Lu _0.2 Si ₂ O ₇ :Ce _0.02 , Gd _1.59 Lu _0.4 Si ₂ O ₇ :Ce _0.01 , Gd _1.385 Lu _0.6 Si ₂ O ₇ :Ce _0.015 , Gd _1.38 Lu _0.6 Si ₂ O ₇ :Ce _0.02 , Gd _0.75 Lu _1.2 Si ₂ O ₇ :Ce _0.05 , Gd _0.73 Lu _1.25 Si ₂ O ₇ :Ce _0.02 , Gd _1.57 Lu _0.4 Si ₂ O ₇ :Ce _0.03 , Gd _1.37 Lu _0.6 Si ₂ O ₇ :Ce _0.02 , Gd _1.385 Lu _0.6 Si ₂ O ₇ : Ce _0.015 , Gd _1.48 Lu _0.5 Si ₂ O ₇ : Ce _0.02 , Gd _1.385 Lu _0.6 Si ₂ O ₇ : Ce _0.015 , Gd _1.385 Lu _0.6 Si ₂ O ₇ : Ce _0.015 and Gd _{1 .385} Lu _0.6 Si ₂ O ₇ :Ce _0.015 .

The present invention also protects a method for preparing the above-mentioned cerium-activated rare earth silicate inorganic scintillating material, which is synthesized by a high-temperature solid phase method and comprises the following steps:

S1. _{Gadolinium oxide (Gd2O3} ₎ _, _{lutetium oxide (Lu2O3} ₎ , cerium dioxide ( _CeO2 ) and a first silicon dioxide ( _SiO2 ) are weighed respectively according to the stoichiometric ratio of _Gd2 _-xyLuxSi2O7 _: _Cey , and a second silicon dioxide is added, wherein the mass of the second silicon dioxide is 0.5-5wt% of the mass of the first silicon dioxide, and then the raw materials are pre-sintered respectively, and then fully ground and mixed to obtain a mixture;

S2. After pre-pressing the mixture, place it in a reaction vessel, bake it in an air atmosphere, and cool it naturally to room temperature to obtain a dense cerium-activated rare earth silicate inorganic scintillating material.

The purpose of adding excess silicon dioxide in step S1 is to ensure obtaining a Gd _2-xy _Lux Si ₂ O ₇ :Ce _y sample, avoid apatite impurity phase and help obtain Ce ³⁺ doped material in air atmosphere. Fully grinding is fully grinding in an agate mortar or a ball mill.

After pre-pressing in step S2, the specific steps of placing in the reaction container are: loading the mixture into a rubber mold, maintaining the pressure at 300 MPa for 5 minutes in a cold isostatic press to obtain a cylindrical pre-pressed raw material, and then transferring it to a platinum sheet or a platinum crucible and placing it in the reaction container. The pre-pressed raw material cannot use a corundum crucible, otherwise the sample is easy to react with corundum to cause the sample to melt and produce a large amount of apatite impurities and introduce aluminum impurities.

Step S2 is naturally cooled to room temperature, and the specific steps of obtaining a dense cerium-activated rare earth silicate inorganic scintillating material are: naturally cooled to room temperature to obtain a dense cerium-activated rare earth silicate ceramic. To obtain a powder material, the obtained rare earth silicate ceramic product can be taken out and ground evenly to obtain a powder rare earth silicate scintillating material.

Preferably, the pre-sintering condition in step S1 is 850°C to 950°C for 2.5 to 3.5 hours, and the raw materials are fully ground and mixed in an ethanol solvent. Even.

Preferably, the specific steps of roasting in step S2 and naturally cooling to room temperature are: heating from room temperature to 1600° C. to 1650° C. for 9.5 to 10.5 hours, keeping the temperature for 2.5 to 3.5 hours, and then naturally cooling to room temperature.

The ceramic and powder of the rare earth silicate scintillating material can be synthesized by a high temperature solid phase method, while the crystal can be synthesized by a melt growth method (taking the Czochralski method as an example).

The present invention also protects a method for preparing the above cerium-activated rare earth silicate inorganic scintillating material, which is synthesized by a melt growth method and comprises the following steps:

SS1. Gadolinium oxide, lutetium oxide, cerium dioxide and _silicon _dioxide are weighed respectively according to the stoichiometric ratio of Gd2 _- _xyLuxSi2O7 : _Cey , and then the raw materials are pre-sintered respectively, and then fully ground and mixed to obtain a mixture;

SS2, after pre-pressing the mixture, placing it in a reaction vessel, calcining it in an air atmosphere, and naturally cooling it to room temperature to obtain a dense cerium-activated rare earth silicate inorganic scintillating material;

SS3, placing the rare earth silicate inorganic scintillating material obtained in step SS2 into an iridium crucible of a pulling furnace, filling it with nitrogen or argon, and then melting it by medium frequency induction heating;

SS4. Using iridium wire or subsequently optimized oriented crystal as seed crystal, the crystal is grown by rotational pulling at a rate of 0.1 to 1 mm per hour and 5 to 20 revolutions per minute to obtain a rare earth silicate inorganic scintillating material in crystalline form.

In step SS1, when the optical floating zone method is used for crystal growth, the excess amount of silicon dioxide (SiO ₂ ) is about 5 mol %.

After pre-pressing in step SS2, the specific steps of placing in the reaction container are: loading the mixture into a rubber mold, maintaining the pressure at 300 MPa for 5 minutes in a cold isostatic press to obtain a cylindrical pre-pressed raw material, and then transferring it to a platinum sheet or a platinum crucible and placing it in the reaction container. The pre-pressed raw material cannot use a corundum crucible, otherwise the sample is easy to react with corundum to cause the sample to melt and produce a large amount of apatite impurities and introduce aluminum impurities.

In step SS3, oxygen-nitrogen or oxygen-argon mixed gas is not used because oxygen will oxidize the expensive iridium crucible.

The crucible in step SS4 can also be a tungsten/molybdenum crucible to save the cost of growing crystals. In addition, when the micro-pull-down method is used to grow crystals, iridium wire is used as a seed crystal to pull down the crystal at a rate of 0.2 mm per minute.

The present invention also protects the application of the cerium-activated rare earth silicate inorganic scintillating material in the field _of radiation detection and imaging. Under X-ray excitation, _the Gd2 _- _xyLuxSi2O7 : _Cey rare earth scintillating material proposed in the present invention has excellent radiation luminescence intensity. The application specifically refers to the application in the field of radiation detection and imaging such as nuclear well logging or nuclear medical imaging.

Compared with the prior art, the present invention has the following advantages:

1. The co-doping of Lu ³⁺ in the present invention significantly improves the disadvantage of non-isotropic melting of Gd ₂ Si ₂ O _7. As shown in FIG1 , Gd ₂ Si ₂ O ₇ is completely transformed into another compound, i.e., Gd _9.33 (SiO ₄ ) ₆ O ₂ with apatite structure after melting, so it is impossible to grow Gd ₂ Si ₂ O ₇ crystals by the Czochralski method. FIG2 shows that Gd _1.4 Lu _0.6 Si ₂ O ₇ co-doped with Lu ³⁺ still maintains the orthorhombic phase structure after partial melting, and transforms into the low temperature phase of Gd _1.4 Lu _0.6 Si ₂ O ₇ after complete melting. The chemical composition of Gd _1.4 Lu _0.6 Si ₂ O ₇ does not change during the melting and cooling process, but it undergoes a high and low temperature phase transition. Therefore, Gd _1.4 Lu _0.6 Si ₂ O ₇ crystals can be grown by the Czochralski method, but the insulation structure and cooling process need to be further optimized (similar to the growth of high and low temperature phase BBO crystals).

2. The co-doping of Lu ³⁺ proposed in the present invention will not significantly reduce the radiation luminescence intensity of the material. As shown in Figures 3 and 4, the material has excellent radiation luminescence intensity, which is more than 1.5 times that of LYSO:Ce crystal.

3. The co-doping of Lu ³⁺ proposed in the present invention increases the density of the material and enhances the absorption of high-energy rays.

Description of the drawings:

Fig. 1 XRD comparison diagram of Gd ₂ Si ₂ O ₇ before and after melting;

Fig. 2 XRD comparison of Gd _1.4 Lu _0.6 Si ₂ O ₇ before and after melting;

Fig. 3 Comparison of the radioluminescence spectra of Gd _1.39 Lu _0.6 Si ₂ O ₇ :Ce _0.01 and LYSO:Ce crystals;

Fig. 4 Comparison of the radioluminescence spectra of Gd _0.79 Lu _1.2 Si ₂ O ₇ :Ce _0.01 and LYSO:Ce crystals;

Fig. 5 Emission spectrum of Gd _1.79 Lu _0.2 Si ₂ O ₇ :Ce _0.01 ;

Fig. 6 Excitation spectrum of Gd _1.79 Lu _0.2 Si ₂ O ₇ :Ce _0.01 ;

Fig. 7 XRD and refinement results of Gd _1.8 Lu _0.2 Si ₂ O ₇ ;

Fig. 8 XRD and refinement results of Gd _1.4 Lu _0.6 Si ₂ O ₇ ;

Fig. 9 Schematic diagram of the structure of Gd _1.4 Lu _0.6 Si ₂ O ₇ ;

Fig. 10 Emission spectrum of Gd _1.39 Lu _0.6 Si ₂ O ₇ :Ce _0.01 ;

Fig. 11 Excitation spectrum of Gd _1.39 Lu _0.6 Si ₂ O ₇ :Ce _0.01 ;

Fig. 12 XRD and refinement results of Gd _0.8 Lu _1.2 Si ₂ O ₇ ;

Fig. 13 Schematic diagram of the structure of Gd _0.8 Lu _1.2 Si ₂ O ₇ ;

Fig. 14 Emission spectrum of Gd _0.79 Lu _1.2 Si ₂ O ₇ :Ce _0.01 ;

Fig. 15 Excitation spectrum of Gd _0.79 Lu _1.2 Si ₂ O ₇ :Ce _0.01 ;

Fig. 16 XRD and refinement results of Gd _0.75 Lu _1.25 Si ₂ O ₇ .

Specific implementation method:

The following examples are provided to further illustrate the present invention, but are not intended to limit the present invention.

Unless otherwise defined, all professional terms used hereinafter have the same meaning as those generally understood by those skilled in the art. The professional terms used herein are only for the purpose of describing specific embodiments and are not intended to limit the scope of protection of the present invention. Unless otherwise specified, the experimental materials and reagents herein are conventional commercial products in the art.

Example 1

Synthesis of Gd _1.79 Lu _0.2 Si ₂ O ₇ :Ce _0.01 ceramic: 3.2444 g of gadolinium oxide, 0.3979 g of lutetium oxide, 0.0172 g of cerium oxide and 1.2376 g of silicon dioxide were fully ground in an agate mortar or ball mill, placed in a rubber mold with an inner diameter of Φ15 mm, sealed, and placed in a cold isostatic press. The cylindrical pre-pressed raw material is obtained by maintaining the pressure at 300MPa for 5 minutes, and then transferred to a platinum sheet or a platinum crucible and placed in a high-temperature furnace, and calcined at 1650℃ for 3 hours in an air atmosphere, and naturally cooled to room temperature to obtain a dense cerium-activated rare earth silicate ceramic. The ceramic can be ground into powder to obtain a powder material.

The obtained rare earth silicate ceramics were tested. Figure 5 is the fluorescence emission spectrum of the material. Under the excitation of 330nm wavelength, the material shows a typical double peak emission of Ce ³⁺ 5d ₁ → ² F _J (J＝5/2,7/2) transition, with a peak value of about 360nm. Figure 6 is the excitation spectrum of the material when monitoring 360nm. The broadband excitation band originates from the transition of Ce ³⁺ 4f→5d _i , while the narrow band of ~270nm originates from the Gd ³⁺ 4f-4f transition and the energy transfer from Gd ³⁺ to Ce ³⁺ . In addition, Figure 7 presents the X-ray powder diffraction pattern and refinement results of the Gd _1.8 Lu _0.2 Si ₂ O ₇ material, confirming that the material does have an orthorhombic structure, space group Pnma, and the unit cell parameters are: α＝β＝γ＝90°, Density ρ = 5.61 g/cm ³ . In the present invention, doping Ce ³⁺ (0.001≤y≤0.05) does not significantly change the crystal structure of the material. Based on this, the material of the present invention is clearly different from the (Gd _0.9 Lu _0.1 ) ₂ Si ₂ O ₇ (similar to the crystal structure of Eu ₂ Si ₂ O ₇ and (Gd,La) ₂ Si ₂ O ₇ ) with a triclinic structure disclosed in the prior art CN105969354A and Physica B 2017,527,21-23, which can be confirmed by simply comparing the XRD diagrams of the material of the present invention ( FIG. 7 ) with those of the prior art.

Figure 3 shows the radiative luminescence spectrum of Gd _1.79 Lu _0.2 Si ₂ O ₇ :Ce _0.01 material under X-ray excitation. Compared with the commercial LYSO:Ce crystal, Gd _1.79 Lu _0.2 Si ₂ O ₇ :Ce _0.01 has a stronger radiative luminescence intensity.

Example 2

Synthesis of Gd _1.78 Lu _0.2 Si ₂ O ₇ :Ce _0.02 ceramics: 3.2263g of gadolinium oxide, 0.3979g of lutetium oxide, 0.0344g of cerium oxide and 1.2376g of silicon dioxide are fully and evenly ground in an agate mortar or ball mill, and then sealed after being loaded into a rubber mold with an inner diameter of Φ15 mm, and placed in a cold isostatic press at 300MPa for 5 minutes to obtain a cylindrical pre-pressed raw material, which is then transferred to a platinum sheet or platinum crucible and placed in a high-temperature furnace and calcined at 1650℃ for 3 hours in an air atmosphere, and naturally cooled to room temperature to obtain a dense cerium-activated rare earth silicate ceramic. This ceramic can also be ground into powder to obtain a powder material.

Example 3

Synthesis of Gd _1.59 Lu _0.4 Si ₂ O ₇ :Ce _0.01 ceramics: 2.8819g of gadolinium oxide, 0.7959g of lutetium oxide, 0.0017g of cerium oxide and 1.2136g of silicon dioxide are fully and evenly ground in an agate mortar or ball mill, and then sealed after being loaded into a rubber mold with an inner diameter of Φ15 mm, and placed in a cold isostatic press at 300MPa for 5 minutes to obtain a cylindrical pre-pressed raw material, which is then transferred to a platinum sheet or platinum crucible and placed in a high-temperature furnace and calcined at 1600℃ for 3 hours in an air atmosphere, and naturally cooled to room temperature to obtain a dense cerium-activated rare earth silicate ceramic. This ceramic can also be ground into powder to obtain a powder material.

Example 4

Synthesis of Gd _1.4 Lu _0.6 Si ₂ O ₇ ceramics: 2.5375g of gadolinium oxide, 1.1938g of lutetium oxide and 1.2376g of silicon dioxide are fully ground in an agate mortar or ball mill, put into a rubber mold with an inner diameter of Φ15 mm and sealed, placed in a cold isostatic press at 300MPa for 5 minutes to obtain a cylindrical pre-pressed raw material, then transferred to a platinum sheet or platinum crucible and placed in a high-temperature furnace, and calcined at 1650℃ for 4 hours in an air atmosphere, and naturally cooled to room temperature to obtain a dense cerium-activated rare earth silicate ceramic. This ceramic can also be ground into powder to obtain a powder material.

The prepared Gd _1.4 Lu _0.6 Si ₂ O ₇ material was tested for X-ray powder diffraction and the structure was refined, as shown in Figure 8. In addition, Figure 9 shows a schematic diagram of the structure of the material. It can be found that the material has an orthorhombic structure, space group Pnma, and unit cell parameters are: α＝β＝γ＝90°, Density ρ = 5.78 g/cm ³ .

Example 5

Synthesis of Gd _1.399 Lu _0.6 Si ₂ O ₇ :Ce _0.001 ceramics: 2.5357 g of gadolinium oxide, 1.1938 g of lutetium oxide, 0.0017 g of cerium oxide and 1.2617 g of silicon dioxide are fully ground in an agate mortar or ball mill, and then sealed after being loaded into a rubber mold with an inner diameter of Φ15 mm, and placed in a cold isostatic press at 300 MPa for 5 minutes to obtain a cylindrical pre-pressed raw material, which is then transferred to a platinum sheet or a platinum crucible and placed in a high-temperature furnace and calcined at 1650°C for 4 hours in an air atmosphere, and naturally cooled to room temperature to obtain a dense cerium-activated rare earth silicate ceramic. This ceramic is ground into powder to obtain a powder material. In the present invention, doping Ce ³⁺ (0.001≤y≤0.05) does not significantly change the crystal structure of the material.

Example 6

Synthesis of Gd _1.39 Lu _0.6 Si ₂ O ₇ :Ce _0.01 ceramic: 2.5194g of gadolinium oxide, 1.1938g of lutetium oxide, 0.0172g of cerium oxide and 1.2256g of silicon dioxide are fully ground in an agate mortar or ball mill, and then sealed after being loaded into a rubber mold with an inner diameter of Φ15 mm, and placed in a cold isostatic press at 300MPa for 5 minutes to obtain a cylindrical pre-pressed raw material, which is then transferred to a platinum sheet or a platinum crucible and placed in a high-temperature furnace and calcined at 1650°C for 4 hours in an air atmosphere, and naturally cooled to room temperature to obtain a dense cerium-activated rare earth silicate ceramic. This ceramic is ground into powder to obtain a powder material. In the present invention, doping Ce ³⁺ (0.001≤y≤0.05) does not significantly change the crystal structure of the material.

Figure 10 shows the fluorescence emission spectrum of the material. Under 330nm wavelength excitation, the material exhibits a typical double peak emission of Ce ³⁺ 5d ₁ → ² F _J (J＝5/2,7/2) transition, with a peak value of about 360nm. Figure 11 shows the excitation spectrum of the material when monitoring at 360nm. The broadband excitation band originates from the transition of Ce ³⁺ 4f→5d _i , while the narrow band of ~270nm originates from the Gd ³⁺ 4f-4f transition and the energy transfer from Gd ³⁺ to Ce ³⁺ .

Figure 3 shows the radiative luminescence spectrum of Gd _1.39 Lu _0.6 Si ₂ O ₇ :Ce _0.01 material under X-ray excitation. Compared with the commercial LYSO:Ce crystal, Gd _1.79 Lu _0.2 Si ₂ O ₇ :Ce _0.01 has a stronger radiative luminescence intensity.

Example 7

Synthesis of Gd _1.38 Lu _0.6 Si ₂ O ₇ :Ce _0.02 ceramics: 2.4831 g of gadolinium oxide, 1.1938 g of lutetium oxide, 0.0516 g of cerium oxide and 1.2617 g of silicon dioxide are fully ground in an agate mortar or ball mill, and then sealed after being loaded into a rubber mold with an inner diameter of Φ15 mm, and placed in a cold isostatic press at 300 MPa for 5 minutes to obtain a cylindrical pre-pressed raw material, which is then transferred to a platinum sheet or a platinum crucible and placed in a high-temperature furnace and calcined at 1650°C for 4 hours in an air atmosphere, and naturally cooled to room temperature to obtain a dense cerium-activated rare earth silicate ceramic. This ceramic is ground into powder to obtain a powder material. In the present invention, doping Ce ³⁺ (0.001≤y≤0.05) does not significantly change the crystal structure of the material.

Example 8

Synthesis of Gd _1.35 Lu _0.6 Si ₂ O ₇ :Ce _0.05 ceramic: 2.4469 g of gadolinium oxide, 1.1938 g of lutetium oxide, 0.0861 g of cerium oxide and 1.2376 g of silicon dioxide were fully ground in an agate mortar or ball mill, placed in a rubber mold with an inner diameter of Φ15 mm, sealed, and placed in a cold isostatic press. The cylindrical pre-pressed raw material is obtained by maintaining the pressure at 300 MPa for 5 minutes, and then transferred to a platinum sheet or a platinum crucible and placed in a high-temperature furnace, and calcined at 1650°C for 4 hours in an air atmosphere, and naturally cooled to room temperature to obtain a dense cerium-activated rare earth silicate ceramic. The ceramic is ground into powder to obtain a powder material. In the present invention, doping Ce ³⁺ (0.001≤y≤0.05) does not significantly change the crystal structure of the material.

Embodiment 9

Synthesis of Gd _0.75 Lu _1.2 Si ₂ O ₇ :Ce _0.05 ceramics: 1.3594g of gadolinium oxide, 2.3876g of lutetium oxide, 0.0861g of cerium oxide and 1.2256g of silicon dioxide are fully ground in an agate mortar or ball mill, put into a rubber mold with an inner diameter of Φ15 mm and sealed, placed in a cold isostatic press at 300MPa for 5 minutes to obtain a cylindrical pre-pressed raw material, then transferred to a platinum sheet or platinum crucible and placed in a high-temperature furnace, and calcined at 1650℃ for 2 hours in an air atmosphere, and naturally cooled to room temperature to obtain a dense cerium-activated rare earth silicate ceramic. This ceramic can also be ground into powder to obtain a powder material.

Example 10

Synthesis of Gd _0.8 Lu _1.2 Si ₂ O ₇ ceramics: 1.4500g of gadolinium oxide, 2.3876g of lutetium oxide and 1.2256g of silicon dioxide are fully ground in an agate mortar or ball mill, and then sealed after being loaded into a rubber mold with an inner diameter of Φ15 mm. The raw materials are placed in a cold isostatic press at 300MPa for 5 minutes to obtain cylindrical pre-pressed raw materials, which are then transferred to platinum sheets or platinum crucibles and placed in a high-temperature furnace and calcined at 1650℃ for 2 hours in an air atmosphere. The raw materials are naturally cooled to room temperature to obtain dense cerium-activated rare earth silicate ceramics. The ceramics can be ground into powder to obtain powder materials.

The XRD and refinement results of the Gd _0.8 Lu _1.2 Si ₂ O ₇ ceramic material are shown in FIG12 . FIG13 shows a schematic diagram of its crystal structure. The material has a monoclinic structure, a space group of P2 ₁ /c, and a unit cell parameter range of: α=γ=90°, β=137.395°, Density ρ = 5.99 g/cm ³ In the present invention, doping with Ce ³⁺ (0.001≤y≤0.05) does not significantly change the crystal structure of the material.

Embodiment 11

Synthesis of Gd _0.79 Lu _1.2 Si ₂ O ₇ :Ce _0.01 ceramic: 1.4319 g gadolinium oxide, 2.3876 g lutetium oxide, 0.0172 g cerium oxide and 1.2256 g dichalcogenide Silicon oxide is fully and evenly ground in an agate mortar or ball mill, and then sealed after being loaded into a rubber mold with an inner diameter of Φ15 mm, and placed in a cold isostatic press at 300 MPa for 5 minutes to obtain a cylindrical pre-pressed raw material, which is then transferred to a platinum sheet or a platinum crucible and placed in a high-temperature furnace, and calcined at 1650° C. for 2 hours in an air atmosphere, and naturally cooled to room temperature to obtain a dense cerium-activated rare earth silicate ceramic. This ceramic is ground into powder to obtain a powder material. In the present invention, doping Ce ³⁺ (0.001≤y≤0.05) does not significantly change the crystal structure of the material.

Figure 14 shows the fluorescence emission spectrum of the material. Under the excitation of 339nm wavelength, the material shows the typical double peak emission of Ce ³⁺ 5d ₁ → ² F _J (J＝5/2,7/2) transition, with the peak value at about 375nm. Figure 15 shows the excitation spectrum of the material when monitoring at 375nm. The broadband excitation band originates from the transition of Ce ³⁺ 4f→5d _i , while the narrow band of ~270nm originates from the Gd ³⁺ 4f-4f transition and the energy transfer from Gd ³⁺ to Ce ³⁺ .

Figure 4 shows the radiative luminescence spectrum of Gd _0.79 Lu _1.2 Si ₂ O ₇ :Ce _0.01 material under X-ray excitation. Compared with the commercial LYSO:Ce crystal, Gd _1.79 Lu _0.2 Si ₂ O ₇ :Ce _0.01 has a stronger radiative luminescence intensity.

Example 12

Synthesis of Gd _0.75 Lu _1.25 Si ₂ O ₇ ceramics: 1.3594g of gadolinium oxide, 2.4871g of lutetium oxide, 0.0344g of cerium oxide and 1.3818g of silicon dioxide are fully ground in an agate mortar or ball mill, and then sealed after being loaded into a rubber mold with an inner diameter of Φ15 mm. The raw materials are placed in a cold isostatic press at 300MPa for 5 minutes to obtain cylindrical pre-pressed raw materials, which are then transferred to platinum sheets or platinum crucibles and placed in a high-temperature furnace and calcined at 1650℃ for 3 hours in an air atmosphere. The raw materials are naturally cooled to room temperature to obtain dense cerium-activated rare earth silicate ceramics. The ceramics can be ground into powder to obtain powder materials.

The XRD and refinement results of Gd _0.75 Lu _1.25 Si ₂ O ₇ ceramics are shown in FIG16 . The material has a monoclinic structure space group P2 ₁ /c, and the range of unit cell parameters is: α=γ=90°, β=137.370°, Density ρ = 6.01 g/cm ³ In the present invention, doping with Ce ³⁺ (0.001≤y≤0.05) does not significantly change the crystal structure of the material.

Example 13

Synthesis of Gd _0.73 Lu _1.25 Si ₂ O ₇ :Ce _0.02 ceramics: 1.3231 g of gadolinium oxide, 2.4871 g of lutetium oxide, 0.0344 g of cerium oxide and 1.3818 g of silicon dioxide were fully ground in an agate mortar or ball mill, placed in a rubber mold with an inner diameter of Φ15 mm, sealed, and placed in a cold isostatic press. The cylindrical pre-pressed raw material is obtained by maintaining the pressure at 300MPa for 5 minutes, and then transferred to a platinum sheet or platinum crucible and placed in a high-temperature furnace, and calcined at 1650℃ for 3 hours in an air atmosphere, and naturally cooled to room temperature to obtain a dense cerium-activated rare earth silicate ceramic. The ceramic is ground into powder to obtain a powder material. Doping Ce ³⁺ (0.001≤y≤0.05) will not significantly change the crystal structure of the material.

Embodiment 14

Synthesis of Gd _1.57 Lu _0.4 Si ₂ O ₇ :Ce _0.03 crystal: 71.1406g gadolinium oxide, 19.8966g lutetium oxide, 1.2909g cerium oxide and 30.0400g silicon dioxide were fully ground in an agate mortar or ball mill, and then sealed after being loaded into a rubber mold with an inner diameter of Φ15 mm. The raw material was obtained by pre-pressing it in a cold isostatic press at 300MPa for 5 minutes, and then transferred to a platinum sheet and placed in a high-temperature furnace. It was calcined at 1650℃ for 3 hours in an air atmosphere and naturally cooled to room temperature to obtain a dense cerium-activated rare earth silicate long columnar ceramic. The ceramic was loaded into an optical floating zone furnace, and after being filled with nitrogen, the crystal was grown at a rate of 8 mm per hour.

Embodiment 15

Synthesis of Gd _1.37 Lu _0.6 Si ₂ O ₇ :Ce _0.02 crystal: 62.5313g gadolinium oxide, 29.8449g lutetium oxide, 0.8606g cerium oxide and 30.0400g silicon dioxide are fully ground in an agate mortar or ball mill, put into a rubber mold with an inner diameter of Φ15 mm and sealed, placed in a cold isostatic press at 300MPa for 5 minutes to obtain a cylindrical pre-pressed raw material, then transferred to a platinum sheet or platinum crucible and placed in a high-temperature furnace, and calcined at 1650℃ in an air atmosphere for 3 hours, and naturally cooled to room temperature to obtain a dense cerium-activated rare earth silicate columnar ceramic. The ceramic is loaded into an optical floating zone furnace, filled with nitrogen and crystal growth is carried out at a rate of 7 mm per hour.

Example 16

Synthesis of Gd _1.385 Lu _0.6 Si ₂ O ₇ :Ce _0.015 crystals: 351.4438 g of gadolinium oxide, 167.1314 g of lutetium oxide, 3.6144 g of cerium oxide and 168.2240 g of silicon dioxide were fully ground in an agate mortar or ball mill, placed in a rubber mold with an inner diameter of Φ60 mm and sealed, placed in a cold isostatic press at 300 MPa for 5 minutes to obtain a cylindrical pre-pressed raw material, then transferred to a platinum sheet or platinum crucible and placed in a high-temperature furnace and calcined at 1650°C for 3 hours in an air atmosphere, and naturally cooled to room temperature to obtain a dense cerium-activated rare earth silicate ceramic. The ceramic was loaded into the iridium A crucible (Φ60 mm) was filled with nitrogen, and the oriented crystal was used as a seed crystal to grow the crystal by pulling at a rate of 0.5 mm per hour.

Embodiment 17

Synthesis of Gd _1.48 Lu _0.5 Si ₂ O ₇ :Ce _0.02 crystal: 375.5500g gadolinium oxide, 139.2762g lutetium oxide, 4.8192g cerium oxide and 176.6352g silicon dioxide (5% excess as flux) are fully ground in an agate mortar or ball mill, put into a rubber mold with an inner diameter of Φ60 mm and sealed, placed in a cold isostatic press at 300MPa for 5 minutes to obtain a cylindrical pre-pressed raw material, then transferred to a platinum sheet or platinum crucible and placed in a high-temperature furnace, and calcined at 1650℃ for 3 hours in an air atmosphere, and naturally cooled to room temperature to obtain a dense cerium-activated rare earth silicate ceramic. The ceramic is placed in an iridium crucible (Φ60 mm) of a pulling furnace, filled with nitrogen, and the crystal is pulled and grown at a rate of 0.1-0.4 mm per hour using an oriented crystal as a seed crystal.

Embodiment 18

Synthesis of Gd _1.385 Lu _0.6 Si ₂ O ₇ :Ce _0.015 crystal: 351.4438g gadolinium oxide, 167.1314g lutetium oxide, 3.6144g cerium oxide and 168.2240g silicon dioxide are fully ground in an agate mortar or ball mill, put into a rubber mold with an inner diameter of Φ60 mm and sealed, placed in a cold isostatic press at 300MPa for 5 minutes to obtain a cylindrical pre-pressed raw material, then transferred to a platinum sheet or platinum crucible and placed in a high-temperature furnace, and calcined at 1650℃ for 3 hours in an air atmosphere, and naturally cooled to room temperature to obtain a dense cerium-activated rare earth silicate ceramic. The ceramic is placed in a molybdenum crucible (Φ60 mm) of a pulling furnace, filled with nitrogen, and the crystal is pulled and grown at a rate of 0.5 mm per hour using an oriented crystal as a seed crystal.

Embodiment 19

Synthesis of Gd _1.38 Lu _0.6 Si ₂ O ₇ :Ce _0.02 crystal: 351.4438g gadolinium oxide, 167.1314g lutetium oxide, 4.8192g cerium oxide and 168.2240g silicon dioxide were fully ground in an agate mortar or ball mill, put into a rubber mold with an inner diameter of Φ60 mm and sealed, placed in a cold isostatic press at 300MPa for 5 minutes to obtain a cylindrical pre-pressed raw material, then transferred to a platinum sheet or platinum crucible and placed in a high-temperature furnace, and calcined at 1650℃ for 3 hours in an air atmosphere, and naturally cooled to room temperature to obtain a dense cerium-activated rare earth silicate ceramic. The ceramic was placed in a molybdenum crucible (Φ60 mm) of a pulling furnace, filled with nitrogen, and the crystal was pulled and grown at a rate of 0.5 mm per hour using an oriented crystal as a seed crystal.

Embodiment 20

Synthesis of Gd _1.385 Lu _0.6 Si ₂ O ₇ :Ce _0.015 crystal: 351.4438g gadolinium oxide, 167.1314g lutetium oxide, 3.6144g cerium oxide and 168.2240g silicon dioxide are fully ground in an agate mortar or ball mill, put into a rubber mold with an inner diameter of Φ60 mm and sealed, placed in a cold isostatic press at 300MPa for 5 minutes to obtain a cylindrical pre-pressed raw material, then transferred to a platinum sheet or platinum crucible and placed in a high-temperature furnace, and calcined at 1650℃ for 3 hours in an air atmosphere, and naturally cooled to room temperature to obtain a dense cerium-activated rare earth silicate ceramic. The ceramic is placed in a tungsten crucible (Φ60 mm) of a pulling furnace, filled with nitrogen, and the crystal is pulled and grown at a rate of 0.5 mm per hour using an oriented crystal as a seed crystal.

Embodiment 21

Synthesis of Gd _1.385 Lu _0.6 Si ₂ O ₇ :Ce _0.015 crystal: 2.8275g gadolinium oxide, 4.7752g lutetium oxide, 0.0688g cerium oxide and 2.4032g silicon dioxide are fully ground in an agate mortar or ball mill, put into a rubber mold with an inner diameter of 15 mm and sealed, placed in a cold isostatic press at 300MPa for 5 minutes to obtain a cylindrical pre-pressed raw material, then transferred to a platinum sheet or platinum crucible and placed in a high-temperature furnace, and calcined at 1650℃ for 3 hours in an air atmosphere, and naturally cooled to room temperature to obtain a dense cerium-activated rare earth silicate ceramic. The ceramic is placed in an iridium crucible of a micro-pulling furnace, filled with nitrogen, and the crystal is pulled down at a rate of 0.2 mm per minute using an iridium wire as a seed crystal.

The description of the above embodiments is only used to help understand the technical solution and core ideas of the present invention. It should be pointed out that for technicians in this technical field, several improvements and modifications can be made to the present invention without departing from the principles of the present invention. These improvements and modifications also fall within the scope of protection of the claims of the present invention.

Claims

A cerium-activated rare earth silicate inorganic scintillating material, characterized in that the material chemical composition expression is: Gd 2-xy Lu x Si 2 O 7 :Ce y , and the value range of x is 0.2≤x≤0.6 and 1.2≤x≤1.25, and the value range of y is 0.001≤y≤0.05.
The cerium-activated rare earth silicate inorganic scintillating material according to claim 1 is characterized in that when the value range of x is 0.2≤x≤0.6 and the value range of y is 0.001≤y≤0.05, the material has an orthorhombic structure space group Pnma, and the range of unit cell parameters is: α＝β＝γ＝90°, Density ρ=5.61-5.78 g/cm 3 ; when the value range of x is 1.2≤x≤1.25, and the value range of y is 0.001≤y≤0.05, the material has a monoclinic structure space group P2 1 /c, and the range of unit cell parameters is: α=γ=90°, β=137.395～137.370°, Density ρ = 5.99-6.01 g/cm 3 .
The cerium-activated rare earth silicate inorganic scintillating material according to claim 1 or 2 is characterized in that the value range of x is 0.2≤x≤0.6 and 1.2≤x≤1.25, and the value range of y is 0.001≤y＜0.002.
The cerium-activated rare earth silicate inorganic scintillating material according to claim 1 or 2 is characterized in that the value range of x is 0.2≤x≤0.6 and 1.2≤x≤1.25, and the value range of y is 0.002＜y≤0.05.
The cerium-activated rare earth silicate inorganic scintillating material according to claim 1 is characterized in that when the value range of x is 0.2≤x≤0.6, the value range of y is 0.01≤y≤0.05, and when the value range of x is 1.2≤x≤1.25, the value range of y is 0.01≤y≤0.04.
0.02 、Gd 1.57 Lu 0.4 Si 2 O 7 :Ce 0.03 、Gd 1.37 Lu 0.6 Si 2 O 7 :Ce 0.04 、Gd 1.59 Lu 0.4 Si 2 O 7 :Ce 0.015 、Gd 1.38 Lu 0.6 Si 2 O 7 :Ce 0.02 、Gd 0.75 Lu 1.2 Si 2 O 7 :Ce 0.05 、Gd 0.73 Lu 1.25 Si 2 O 7 :Ce 0.02 、Gd 1.57 Lu 0.4 Si 2 O 7 :Ce 0.03 、 Gd 1.37 Lu 0.6 Si 2 O 7 :Ce 0.045 、Gd 1.38 Lu 0.6 Si 2 O 7 :Ce 0.02 0.6 Si 2 O 7 : Ce 0.02 , Gd 1.385 Lu 0.6 Si 2 O 7 : Ce 0.015 , Gd 1.48 Lu 0.5 Si 2 O 7 : Ce 0.02 , Gd 1.385 Lu 0.6 Si 2 O 7 : Ce 0.015 , Gd 1.385 Lu 0.6 Si 2 O 7 : Ce 0.015 and Gd 1.385 Lu 0.6 Si 2 O 7 : Ce 0.015 .
The method for preparing the cerium-activated rare earth silicate inorganic scintillating material according to claim 1 is characterized in that it is synthesized by a high-temperature solid phase method, comprising: The steps are as follows:

S1. According to the stoichiometric ratio of Gd2 -xyLuxSi2O7 : Cey , gadolinium oxide, lutetium oxide, cerium dioxide and a first silicon dioxide are weighed respectively, and a second silicon dioxide is added, wherein the mass of the second silicon dioxide is 0.5-5wt % of the mass of the first silicon dioxide, and then the raw materials are pre-sintered respectively, and then fully ground and mixed to obtain a mixture;

S2. After pre-pressing the mixture, place it in a reaction vessel, bake it in an air atmosphere, and cool it naturally to room temperature to obtain a dense cerium-activated rare earth silicate inorganic scintillating material.
The preparation method according to claim 7 is characterized in that the specific steps of roasting in step S2 and naturally cooling to room temperature are: heating from room temperature to 1600°C to 1650°C for 9.5 to 10.5 hours, keeping warm for 2.5 to 3.5 hours, and then naturally cooling to room temperature.
The method for preparing the cerium-activated rare earth silicate inorganic scintillating material according to claim 1 is characterized in that the synthesis is carried out by a melt growth method, comprising the following steps:

SS1. Gadolinium oxide, lutetium oxide, cerium dioxide and silicon dioxide are weighed respectively according to the stoichiometric ratio of Gd2 - xyLuxSi2O7 : Cey , and then the raw materials are pre-sintered respectively, and then fully ground and mixed to obtain a mixture;

SS2, after pre-pressing the mixture, placing it in a reaction vessel, calcining it in an air atmosphere, and naturally cooling it to room temperature to obtain a dense cerium-activated rare earth silicate inorganic scintillating material;

SS3, placing the rare earth silicate inorganic scintillating material obtained in step SS2 into an iridium crucible and a pulling furnace, filling with nitrogen or argon, and then melting it by medium frequency induction heating;

SS4. Using iridium wire or subsequently optimized oriented crystal as seed crystal, the crystal is grown by rotational pulling at a rate of 0.1 to 1 mm per hour and 5 to 20 revolutions per minute to obtain a rare earth silicate inorganic scintillating material in crystalline form.
Application of the cerium-activated rare earth silicate inorganic scintillating material according to any one of claims 1 to 6 in the field of radiation detection and imaging.