Praseodymium ion doped yttrium gallium aluminum garnet scintillation crystal material and preparation method and application thereof

Abstract

The invention provides a praseodymium ion-doped yttrium gallium aluminum garnet scintillation crystal material and a preparation method and application thereof, and the method comprises the following steps: weighing required raw materials according to a stoichiometric ratio specified by a chemical formula of the scintillation crystal material, grinding, tabletting and sintering for many times to prepare a polycrystalline raw material, and sintering to obtain the praseodymium ion-doped yttrium gallium aluminum garnet scintillation crystal material. And then preparing the high-quality praseodymium ion doped yttrium gallium aluminum garnet scintillation crystal material by adopting a micro down-draw method. According to the technical scheme, the yttrium aluminum garnet crystal is doped with praseodymium ions, so that a unique 4f electronic structure of the yttrium aluminum garnet crystal can be utilized to endow the crystal material with excellent luminescence performance, especially 5d-4f transition allowed by complete spin-space, and the crystal material has efficient scintillation response capability; by introducing the gallium element, part of the aluminum element can be replaced by the gallium element, so that the conduction band of the garnet system scintillator is reduced, some shallow energy level traps such as oxygen vacancies are submerged, and the scintillation performance of the crystal material is effectively improved.

Description

Technical Field

[0001] The present invention relates to the technical field of scintillation crystal materials, and in particular to a praseodymium ion-doped yttrium gallium aluminum garnet scintillation crystal material and a preparation method and application thereof. Background Art

[0002] Scintillating crystals are luminescent materials that can produce efficient fluorescence emission under the stimulation of high-energy rays or particles. The research focus is mainly on improving light output and energy resolution and reducing scintillation attenuation. The currently developed praseodymium ion-activated scintillating crystals, such as Y3Al5O 12 :Pr, Lu3Al5O 12 :Pr, Gd2Si2O7:Pr, YAlO3:Pr and other single crystals have achieved light yields of more than 2290ph / MeV, especially the garnet system scintillator, the light yield can exceed 26000ph / MeV, but there is still a certain gap from the theoretical light yield proposed by Dorenbos. The low light yield also limits the application and promotion of garnet-based scintillators.

[0003] In view of this, it is necessary to design an improved praseodymium ion-doped yttrium gallium aluminum garnet scintillation crystal material and a preparation method and application thereof to solve the above problems. Summary of the invention

[0004] The object of the present invention is to provide a praseodymium ion-doped yttrium gallium aluminum garnet scintillation crystal material and a preparation method and application thereof.

[0005] To achieve the above-mentioned purpose, the present invention provides a praseodymium ion-doped yttrium gallium aluminum garnet scintillation crystal material, the chemical formula of which is yPr:Y 3(1-y) (Al 1-x Ga x )5O 12 , where 0<x<1, 0<y<0.3.

[0006] Furthermore, the present invention also provides a method for preparing the above-mentioned praseodymium ion-doped yttrium gallium aluminum garnet scintillation crystal material, comprising the following steps:

[0007] According to the chemical formula yPr:Y 3(1-y) (Al 1-x Ga x )5O 12 The required mass of praseodymium oxide, gallium oxide, yttrium oxide and aluminum oxide are uniformly mixed in a stoichiometric ratio and then sintered to obtain a polycrystalline raw material; the polycrystalline raw material is grown by a micro-pull-down method, and after the growth is completed, the temperature is cooled to room temperature to obtain the praseodymium ion-doped yttrium gallium aluminum garnet scintillation crystal material.

[0008] Preferably, the sintering treatment is carried out at a temperature of 1300-1600° C. and for a time of 5-15 hours.

[0009] Preferably, the heating rate of the sintering process is 50-250° C. / h; preferably, the heating rate is 200° C. / h.

[0010] Preferably, the temperature of the growth process of the micro-pull-down method is 1800-2000° C., and the pull-down speed is 0.5-3 mm / h.

[0011] Preferably, the sintering process is performed 1-3 times.

[0012] Preferably, the sintering process is carried out at a temperature of 1500° C. and for a time of 10 h.

[0013] Preferably, the temperature of the growth process is 1940-1960° C.; and the pulling speed is 1-2.5 mm / h.

[0014] Preferably, the cooling rate during cooling is 500° C. / h.

[0015] In particular, the praseodymium ion-doped yttrium gallium aluminum garnet scintillation crystal material prepared by the present invention can be applied to nuclear medical imaging, industrial non-destructive testing, safety inspection, environmental monitoring, geological exploration, oil well drilling, high energy physics and astronomy and space physics.

[0016] The beneficial effects of the present invention are:

[0017] The preparation method of the praseodymium ion-doped yttrium gallium aluminum garnet scintillation crystal material provided by the present invention comprises the following steps: weighing the required raw materials according to the stoichiometric ratio specified by the chemical formula of the scintillation crystal material, grinding, pressing and sintering the raw materials to obtain polycrystalline raw materials for multiple times, and then using a micro-pull-down method to obtain high-quality praseodymium ion-doped yttrium gallium aluminum garnet scintillation crystal material. The above technical scheme, by doping praseodymium ions in yttrium aluminum garnet crystals, can use its unique 4f electronic structure to give the crystal material excellent luminescence properties, especially the fully spin-parity allowed 5d→4f transition, so that it has efficient scintillation response capability; by introducing gallium elements, gallium elements can be used to replace part of the aluminum elements to reduce the conduction band of the garnet system scintillator, so that some shallow energy level traps such as oxygen vacancies are submerged, and the scintillation performance of the crystal material is effectively improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 This is the XRD pattern of the scintillation crystal material prepared in Example 1 of the present invention;

[0019] Figure 2 This is a fluorescence excitation emission diagram of the scintillation crystal material prepared in Example 1 of the present invention;

[0020] Figure 3This is a scintillation decay lifetime diagram of the scintillation crystal material prepared in Example 1 of the present invention;

[0021] Figure 4 This is the XRD pattern of the scintillation crystal material prepared in Example 2 of the present invention;

[0022] Figure 5 This is a fluorescence excitation emission diagram of the scintillation crystal material prepared in Example 2 of the present invention;

[0023] Figure 6 This is a scintillation decay lifetime diagram of the scintillation crystal material prepared in Example 2 of the present invention;

[0024] Figure 7 This is the XRD pattern of the scintillation crystal material prepared in Example 3 of the present invention;

[0025] Figure 8 This is a fluorescence excitation emission diagram of the scintillation crystal material prepared in Example 3 of the present invention;

[0026] Fig. 9 This is a scintillation decay lifetime diagram of the scintillation crystal material prepared in Example 3 of the present invention;

[0027] Fig.10 This is the XRD pattern of the scintillation crystal material prepared in Example 4 of the present invention;

[0028] Fig.11 This is a fluorescence excitation emission diagram of the scintillation crystal material prepared in Example 4 of the present invention;

[0029] Fig.12 This is a scintillation decay lifetime diagram of the scintillation crystal material prepared in Example 4 of the present invention;

[0030] Fig.13 The multi-channel energy spectra of the scintillation crystal materials prepared in Examples 1 to 4 of the present invention. DETAILED DESCRIPTION

[0031] In order to make the purpose, technical solutions and advantages of the present invention more clear, the present invention is described in detail below with reference to the accompanying drawings and specific embodiments.

[0032] It should also be noted that, in order to avoid obscuring the present invention due to unnecessary details, only structures and / or processing steps closely related to the scheme of the present invention are shown in the drawings, while other details that are not closely related to the present invention are omitted.

[0033] In addition, it should be noted that the terms "comprises", "includes" or any other variations thereof are intended to cover non-exclusive inclusion, so that a process, method, article or apparatus that includes a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or apparatus.

[0034] In one aspect, the present invention provides a praseodymium ion-doped yttrium gallium aluminum garnet scintillation crystal material, the chemical formula of which is yPr:Y 3(1-y) (Al 1-x Ga x )5O 12 , wherein 0<x<1, 0<y<0.3; the above crystal material is a single crystal material, belongs to the cubic crystal system, and the space group is Ia3d.

[0035] Furthermore, the present invention also provides a method for preparing the above-mentioned praseodymium ion-doped yttrium gallium aluminum garnet scintillation crystal material, comprising the following steps: 3(1-y) (Al 1-x Ga x )5O 12 The required mass of praseodymium oxide, gallium oxide, yttrium oxide and aluminum oxide are uniformly mixed in a stoichiometric ratio and then sintered to obtain a polycrystalline raw material; the polycrystalline raw material is grown by a micro-pull-down method, and after the growth is completed, the temperature is lowered to room temperature to obtain a praseodymium ion-doped yttrium gallium aluminum garnet scintillation crystal material.

[0036] In the above technical scheme, by doping praseodymium ions into yttrium aluminum garnet crystals, the unique 4f electronic structure can be used to give the crystal material excellent luminescence properties, especially the fully spin-parity allowed 5d→4f transition, so that it has efficient scintillation response capability; by introducing gallium elements, gallium elements can be used to replace part of the aluminum elements to reduce the conduction band of the garnet system scintillator, so that some shallow energy level traps such as oxygen vacancies are submerged, effectively improving the scintillation performance of the crystal material.

[0037] As an embodiment of the present invention, the sintering temperature is 1300-1600°C, the time is 5-15h, and the heating rate from room temperature to the target temperature is 50-250°C / h. Preferably, the sintering temperature is 1500°C, the time is 10h, and the heating rate is 200°C / h.

[0038] As an embodiment of the present invention, in order to ensure the sintering effect, the sample needs to be ground and pressed before the sintering process, and sintered multiple times. After each sintering, the sample is ground and pressed again before entering the next sintering step. Preferably, the number of sintering times is 1-3 times. It should be noted that grinding and pressing only need to be performed according to the conventional operation method in the field, and there are no special requirements here.

[0039] As an embodiment of the present invention, the process of growing the polycrystalline raw material is carried out in a protective gas atmosphere, and the protective gas is a non-reactive gas, specifically high-purity nitrogen or argon, preferably nitrogen.

[0040] As an embodiment of the present invention, the temperature of the growth process of the micro-pull-down method is 1800-2000° C., preferably 1940-1960° C.; the pull-down speed is 0.5-3 mm / h, more preferably 1-2.5 mm / h.

[0041] As an implementation mode of the present invention, after the crystal growth is completed, the cooling rate of the cooling process is 500° C. / h.

[0042] In particular, the scintillation crystal material prepared by the method proposed in the present invention can be applied to nuclear medicine imaging, industrial non-destructive testing, safety inspection, environmental monitoring, geological exploration, oil well drilling, high energy physics and astronomy and space physics.

[0043] The praseodymium ion-doped yttrium gallium aluminum garnet scintillation crystal material and its preparation method and application proposed by the present invention are further described below in conjunction with specific embodiments:

[0044] Example 1

[0045] In this example, 1% Pr:Y was prepared by micro-pulling method. 2.97 Al5O 12 The crystal preparation method comprises the following steps:

[0046] According to the chemical formula 1% Pr:Y 2.97 Al5O 12 Weigh the required mass of Pr6O 11 , Al2O3, and Y2O3 were mixed and ground evenly, pressed into tablets, and reacted in a muffle furnace at 1500°C for 10 hours for the first sintering; after the sintering was completed, the sample was taken out and ground and mixed evenly again, pressed into tablets, and sintered for the second time in a muffle furnace at 1500°C for 10 hours; after the second sintering was completed, the sample was ground and mixed evenly again, pressed into tablets, and sintered for the third time in a muffle furnace at 1500°C for 10 hours to obtain a polycrystalline raw material; wherein, the heating rate of the first sintering, the second sintering, and the third sintering from room temperature to 1500°C was 200°C / h;

[0047] The polycrystalline raw material prepared in the above steps is added into a Φ15×50mm 3 The iridium crucible was placed in a micro-pull-down furnace. The micro-pull-down method was used in a N2 atmosphere with a growth temperature of 1950°C and a pull-down speed of 1mm / h. After the growth was completed, the crystal was cooled to room temperature at a rate of 500°C / h to grow a Φ5×25mm3 It should be noted that the crucible size in the above process can also be adjusted according to actual needs, as long as it can meet the actual needs, and it is not limited to this here.

[0048] The XRD pattern of the crystalline material prepared in this embodiment is as follows: Figure 1 As shown in the figure, there is no impurity peak compared with the standard card, indicating that the doping of Pr ions will not affect the crystal structure; the fluorescence excitation emission diagram of the crystal material is shown in Figure 2 As shown, the fd emission peak of Pr ions is at 300-450nm, which is within the sensitive response range of the photomultiplier tube; the scintillation decay lifetime diagram is shown in Figure 3 As shown, the scintillation decay lifetime is found to be 26.62ns after fitting.

[0049] Example 2

[0050] This example uses the micro-pull-down method to grow 1% Pr:Y 2.97 Al 4.75 Ga 0.25 O 12 The crystal preparation method comprises the following steps:

[0051] According to the chemical formula 1% Pr:Y 2.97 Al 4.75 Ga 0.25 O 12 Weigh the required mass of Pr6O 11 , Al2O3, Y2O3 and Ga2O3 are mixed and ground evenly, pressed into tablets, and reacted in a muffle furnace at 1500℃ for 10 hours for the first sintering; after the sintering is completed, the sample is taken out and ground and mixed evenly again, pressed into tablets, and sintered for the second time in a muffle furnace at 1500℃ for 10 hours; after the second sintering is completed, the sample is ground and mixed evenly again, pressed into tablets, and sintered for the third time in a muffle furnace at 1500℃ for 10 hours to obtain a polycrystalline raw material; wherein, the heating rate of the first sintering, the second sintering, and the third sintering from room temperature to 1500℃ is 200℃ / h;

[0052] The polycrystalline raw material prepared in the above steps is added into a Φ15×50mm 3 The iridium crucible was placed in a micro-pull-down furnace. The micro-pull-down method was used in a N2 atmosphere with a growth temperature of 1950°C and a pull-down speed of 1mm / h. After the growth was completed, the crystal was cooled to room temperature at a rate of 500°C / h to grow a Φ5×25mm 3 High quality 1% Pr:YAGG crystal.

[0053] The XRD pattern of the crystalline material prepared in this embodiment is as follows: Figure 4As shown in the figure, there is no impurity peak compared with the standard card, indicating that the doping of Pr and Ga ions does not affect the crystal structure; the fluorescence excitation emission diagram of the crystal material is shown in Figure 5 As shown in the figure, the introduction of Ga element did not shift the emission center of Pr ion. The fd emission band is at 300-450nm, which belongs to the sensitive response range of photomultiplier tube. The scintillation decay lifetime diagram is shown in Figure 6 As shown, the scintillation lifetime is fitted to be 35.31ns, and the results show that the doping of Ga element increases the scintillation lifetime.

[0054] Example 3

[0055] This example uses the micro-pull-down method to grow 1% Pr:Y 2.97 Al 4.5 Ga 0.5 O 12 The crystal preparation method comprises the following steps:

[0056] According to the chemical formula 1% Pr:Y 2.97 Al 4.5 Ga 0.5 O 12 Weigh the required mass of Pr6O 11 , Al2O3, Y2O3 and Ga2O3 are mixed and ground evenly, pressed into tablets, and reacted in a muffle furnace at 1500℃ for 10 hours for the first sintering; after the sintering is completed, the sample is taken out and ground and mixed evenly again, pressed into tablets, and sintered for the second time in a muffle furnace at 1500℃ for 10 hours; after the second sintering is completed, the sample is ground and mixed evenly again, pressed into tablets, and sintered for the third time in a muffle furnace at 1500℃ for 10 hours to obtain a polycrystalline raw material; wherein, the heating rate of the first sintering, the second sintering, and the third sintering from room temperature to 1500℃ is 200℃ / h;

[0057] The polycrystalline raw material prepared in the above steps is added into a Φ15×50mm 3 The iridium crucible was placed in a micro-pull-down furnace. The micro-pull-down method was used in a N2 atmosphere with a growth temperature of 1950°C and a pull-down speed of 1mm / h. After the growth was completed, the crystal was cooled to room temperature at a rate of 500°C / h to grow a Φ5×25mm 3 High quality 1% Pr:YAGG crystal.

[0058] The XRD pattern of the crystalline material prepared in this embodiment is as follows: Figure 7 As shown in the figure, there is no impurity peak compared with the standard card, indicating that the doping of Pr and Ga ions does not affect the crystal structure; the fluorescence excitation emission diagram of the crystal material is shown in Figure 8As shown in the figure, the addition of Ga element does not shift the emission center of Pr ion. The fd emission band is at 300-450nm, which belongs to the sensitive response range of photomultiplier tube. The scintillation decay lifetime diagram is shown in Fig. 9 As shown, the scintillation lifetime is fitted to be 37.22ns, and the scintillation lifetime increases with the increase of Ga elements.

[0059] Example 4

[0060] This example uses the micro-pull-down method to grow 1% Pr:Y 2.97 Al 4.25 Ga 0.75 O 12 The crystal preparation method comprises the following steps:

[0061] According to the chemical formula 1% Pr:Y 2.97 Al 4.25 Ga 0.75 O 12 Weigh the required mass of Pr6O 11 , Al2O3, Y2O3 and Ga2O3 are mixed and ground evenly, pressed into tablets, and reacted in a muffle furnace at 1500℃ for 10 hours for the first sintering; after the sintering is completed, the sample is taken out and ground and mixed evenly again, pressed into tablets, and sintered for the second time in a muffle furnace at 1500℃ for 10 hours; after the second sintering is completed, the sample is ground and mixed evenly again, pressed into tablets, and sintered for the third time in a muffle furnace at 1500℃ for 10 hours to obtain a polycrystalline raw material; wherein, the heating rate of the first sintering, the second sintering, and the third sintering from room temperature to 1500℃ is 200℃ / h;

[0062] The polycrystalline raw material prepared in the above steps is added into a Φ15×50mm 3 The iridium crucible was placed in a micro-pull-down furnace. The micro-pull-down method was used in a N2 atmosphere with a growth temperature of 1950°C and a pull-down speed of 1mm / h. After the growth was completed, the crystal was cooled to room temperature at a rate of 500°C / h to grow a Φ5×25mm 3 High quality 1% Pr:YAGG crystal.

[0063] The XRD pattern of the crystalline material prepared in this embodiment is as follows: Fig.10 As shown in the figure, there is no impurity peak compared with the standard card, indicating that the doping of Pr and Ga ions will not affect the crystal structure; the fluorescence excitation emission diagram of the crystal material is shown in Fig.11 As shown in the figure, the addition of Ga element does not shift the emission center of Pr ion. The fd emission band is at 300-450nm, which belongs to the sensitive response range of photomultiplier tube. The scintillation decay lifetime diagram is shown in Fig.12As shown, the scintillation lifetime is fitted to be 34.41ns, and with the increase of Ga element, the scintillation lifetime shows a decreasing trend.

[0064] The multi-channel energy spectra of the crystalline materials obtained in Examples 1 to 4 are as follows: Fig.13 As shown in the figure, when Ga element is not introduced, the scintillation light output of 1% Pr:YAGG is 67.6% of that of BGO crystal. When the Ga element doping amount is 0.25, the scintillation light output of 1% Pr:YAGG crystal is 85.1% of that of BGO crystal; when the Ga element doping amount is 0.5, the scintillation light output of 1% Pr:YAGG crystal is 97.3% of that of BGO crystal; when the Ga element doping amount is 0.75, the scintillation light output of 1% Pr:YAGG crystal is 108.1% of that of BGO crystal. The data show that the introduction of Ga element can effectively improve the scintillation performance of crystal materials. With the increase of Ga element doping amount, the scintillation light output of the crystal increases accordingly, and the optimal doping amount of Ga element is 0.75.

[0065] In summary, the 1% Pr:YAGG crystal prepared by the present invention can be effectively excited by ultraviolet light, near-ultraviolet light, high-energy rays or particles to obtain a scintillation light output close to or stronger than that of BGO crystal, and obtain a scintillation decay time of less than 40ns, and is a scintillation crystal material with potential application prospects.

[0066] The above embodiments are only used to illustrate the technical solution of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solution of the present invention may be modified or replaced by equivalents without departing from the spirit and scope of the technical solution of the present invention.

Claims

1. A praseodymium ion-doped yttrium gallium aluminum garnet scintillation crystal material, characterized in that: The chemical formula of the scintillation crystal material is yPr:Y 3(1-y) (Al 1-x Ga x )5O 12 , where 0<x<1, 0<y<0.

3.

2. A method for preparing praseodymium ion-doped yttrium gallium aluminum garnet scintillation crystal material, characterized in that: The steps include: According to the chemical formula yPr:Y 3(1-y) (Al 1-x Ga x )5O 12 The required mass of praseodymium oxide, gallium oxide, yttrium oxide and aluminum oxide are uniformly mixed in a stoichiometric ratio and then sintered to obtain a polycrystalline raw material; the polycrystalline raw material is grown by a micro-pull-down method, and after the growth is completed, the temperature is cooled to room temperature to obtain the praseodymium ion-doped yttrium gallium aluminum garnet scintillation crystal material.

3. The preparation method according to claim 2, characterized in that: The sintering process is carried out at a temperature of 1300-1600° C. and for a time of 5-15 hours.

4. The preparation method according to claim 2, characterized in that: The heating rate of the sintering process is 50-250°C / h; preferably, the heating rate is 200°C / h.

5. The preparation method according to claim 2, characterized in that: The temperature of the growth process of the micro-pull-down method is 1800-2000° C., and the pull-down speed is 0.5-3 mm / h.

6. The preparation method according to claim 2, characterized in that: The sintering process is performed 1 to 3 times.

7. The preparation method according to claim 3, characterized in that: The sintering process is carried out at a temperature of 1500° C. and for a time of 10 hours.

8. The preparation method according to claim 5, characterized in that: The temperature of the growth process is 1940-1960°C; the pulling speed is 1-2.5 mm / h.

9. The preparation method according to claim 2, characterized in that: The cooling rate during cooling is 500°C / h.

10. Application of the praseodymium ion-doped yttrium gallium aluminum garnet scintillation crystal material according to claim 1 or the praseodymium ion-doped yttrium gallium aluminum garnet scintillation crystal material prepared by the preparation method according to claim 2 in nuclear medical imaging, industrial non-destructive testing, safety inspection, environmental monitoring, geological exploration, oil well drilling, high energy physics and astronomy and space physics.

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