Method for preparing fluorinion doped lead tungstate scintillation crystal

A technology of scintillation crystal and lead tungstate, which is applied to the preparation of fluoride ion-doped lead tungstate scintillation crystal. Gas phase transport diffusion doped fluoride ion into the field of pure PWO4 crystal, which can solve the problem of volatilization, uneven distribution, and emission wavelength. , the light output is not the same along the growth direction, etc., to achieve high light output, improve distribution uniformity, and improve the effect of uniformity

Inactive Publication Date: 2004-11-17
SHANGHAI INST OF OPTICS & FINE MECHANICS CHINESE ACAD OF SCI
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AI Technical Summary

Problems solved by technology

[0006] (1) Due to PbF 2 The melting point of PbWO is relatively low (about 850°C), while the melting point of PbWO crystal is about 1120°C. 2 It is easy to volatilize from the melt, resulting in PbF 2 Difficult to incorporate into the PWO lattice;
[0007] (2) Due to PbF 2 The volatility of the crystal lattice leads to the inhomogeneity of the distribution of F ions in the crystal lattice along the crystallization direction, which will cause the inhomogeneity of the detection efficiency of the detector made of crystal, and the emission wavelength and light output are not the same along the growth direction. , seriously affecting the accuracy and sensitivity of scintillation detectors

Method used

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  • Method for preparing fluorinion doped lead tungstate scintillation crystal

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Embodiment 1

[0023] Embodiment 1: Prepare 20×20×2mm 3 PWO crystals doped with 100ppm (wt%) F ions

[0024] The process steps of preparation are as follows:

[0025] In the platinum crucible 1, PWO and PbF with pores 2 are placed 2 Mixture block 3, select [PWO] / [PbF 2 ]=98:2 weight ratio;

[0026] 20×20×2mm grown by pulling method or descending method 3 wafers, placed or suspended on platinum wires, plus covered with PWO and PbF 2 The crucible cover of mixing powder 7 and thermocouple 8, the top of the crucible is sealed with a platinum cover 9, and placed in a resistance furnace;

[0027] Heating up to about 500°C, keeping the temperature constant for 20 hours, F ions diffuse into the PWO wafer, and then cooling down to room temperature at a cooling rate of 50°C / h, finally obtaining 100ppm fluorine ion-doped PWO scintillation crystal.

[0028] The light output of the scintillation crystal is about 15% higher than that of the pure PWO crystal, and the crystal can be applied in the ...

Embodiment 2

[0029] Embodiment 2: Prepare 50×50×20mm 3 Doped 200ppm (wt%) F ion PWO crystal

[0030] The process steps of preparation are as follows:

[0031] In the platinum crucible 1, PWO and PbF with pores 2 are placed 2 Mixture block 3, select [PWO] / [PbF 2 ]=60:40 weight ratio;

[0032] 50×50×20mm grown by pulling method or descending method 3 wafers, placed or suspended on platinum wires, plus covered with PWO and PbF 2 The crucible cover of mixing powder 7 and thermocouple 8, the top of the crucible is sealed with a platinum cover 9, and placed in a resistance furnace;

[0033] Heating up to about 700°C, keeping the temperature constant for 60 hours, F ions diffuse into the PWO wafer, and then cooling down to room temperature at a cooling rate of 50°C / h, finally obtaining 200ppm fluorine ion-doped PWO scintillation crystals.

[0034] The light output of the scintillation crystal is about 3 times higher than that of the pure PWO crystal, and the crystal can be applied to high-...

Embodiment 3

[0035] Embodiment 3: Prepare 80×80×50mm 3 Doped 350ppm (wt%) F ion PWO crystal

[0036] The process steps of preparation are as follows:

[0037] In the platinum crucible 1, PWO and PbF with pores 2 are placed 2 Mixture block 3, select [PWO] / [PbF 2 ]=0:100 weight ratio;

[0038] 80×80×50mm grown by pulling method or descending method 3 wafers, placed or suspended on platinum wires, plus covered with PWO and PbF 2 The crucible cover of mixing powder 7 and thermocouple 8, the top of the crucible is sealed with a platinum cover 9, and placed in a resistance furnace;

[0039] Heating up to about 800°C, constant temperature for 400 hours, F ions diffused into the PWO wafer, and then cooling down to room temperature at a cooling rate of 50°C / h, finally obtaining 350ppm fluorine ion-doped PWO scintillation crystal.

[0040] The light output of the scintillation crystal is about 5 times higher than that of the pure PWO crystal, and the crystal can be applied to high-energy ph...

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Abstract

The invention discloses a method for preparing fluorinion doped lead tungstate scintillation crystal which comprises, utilizing the characteristics of low melting point and easy-volatilization of the PbF2 and gaseous phase transmission balancing technique, regulating the parameters including batch component proportioning, temperature and time in the high temperature, rich fluorine atmosphere, controlling the diffusion of F- ions. The method provided by the invention can improve the evenness for the F ion doping PWO crystallo-luminescence.

Description

technical field [0001] The invention relates to a lead tungstate scintillation crystal, which is a preparation method of a fluoride ion-doped lead tungstate scintillation crystal. Specifically related to a gas phase transport diffusion of fluorine ions (F - ) doped in pure PWO 4 A method for improving the light output performance of a PWO crystal in a crystal. This high light output F:PWO crystal can be widely used in detection devices such as high-energy physics and nuclear medical imaging (PET). Background technique [0002] Lead tungstate crystals with scheelite structure (PbWO 4 , referred to as PWO) belongs to the tetragonal crystal system, and its space group is C 4h 6 (I4 1 / a), the lattice parameters are respectively a=b=0.5456nm and c=1.2020nm. Under the irradiation of high-energy particles (rays), PWO crystals can emit blue light (400-440nm) and green light (480 -500nm) and other intrinsic light, therefore, PWO crystals can meet the requirements of fast cou...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C30B15/04C30B29/32
Inventor 赵广军徐军介明印庞辉勇曾雄辉周圣明周国清
Owner SHANGHAI INST OF OPTICS & FINE MECHANICS CHINESE ACAD OF SCI
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