A method for growing trivalent cerium ion doped yttrium lutetium silicate scintillation crystal

Abstract

The invention relates to a method for growing a Ce<3+> doped lutetium yttrium silicate scintillation crystal. The method is characterized by comprising the concrete steps of (1) weighing and mixing; (2) pressing and sintering; (3) heating for fusing; (4) seeding; (5) high temperature oxygen diffusion; (6) necking, shoulder extending and keeping constant-diameter; (7) cooling; (8) in-situ annealing. According to the invention, a crystal growth furnace is properly modified, so that high-temperature oxygen diffusion and in-situ annealing at a reducing atmosphere can be simultaneously realized, oxygen balance can also be realized, and furthermore, the crystal is not easy to crack and become yellow and the good crystal quality is kept. The success rate for growing the crystal is increased from 40-45% to 75-85%.

Description

technical field [0001] The invention relates to a kind of pulling method to draw Ce 3+ A process method for doping yttrium lutetium silicate crystal belongs to the technical field of crystal growth and electronic control. Background technique [0002] Inorganic scintillation crystals are widely used in various radiation detection fields, such as nuclear medicine, nuclear physics, safety inspection, Extreme condition applications and industrial non-destructive testing, etc. The material system mainly includes Bi 4 Ge 3 o 12 (BGO), PbWO 4 (PWO), CsI(TI), NaI(TI), BaF 2 、Lu 2 SiO 5 (LSO) and yttrium lutetium silicate (LYSO), etc. [0003] Yttrium lutetium silicate (LYSO) scintillation crystal is considered to be the inorganic scintillation crystal material with the best comprehensive performance. Its effective atomic number is 64, its density is 7.1g / cm3, and its light output can reach 38000Mev. Its light output is BGO single crystal 4 to 5 times that of thallium dope...

AI Technical Summary

Problems solved by technology

[0005] Among the patents and literatures reported on LSO / LYSO scintillation crystals, most of them are monopolized by foreign countries (mainly Siemens, Philips and GE), and there are only a handful of patents on oxygen content control, as reported in CN200580006294.8 In order to use high-temperature oxygen diffusion to supplement oxygen, but it cannot be precisely controlled, and can only be judged by visually observing the crystal color. The crystal growth time is long and the temperature is high, and the oxygen content is controlled by visual inspection. This aspect needs further improvement; another example is CN201110417562.2 It is reported that annealing the prepared crystals in a high-temperature furnace under a neutral atmosphere can change the color of the crystals from yellow to transparent or colorless, which not only complicates the process and increases the cost, but also does not strictly control the previous crystal growth process. Aerobic content also presents increased risk of crystal cracking

[0006] The present invention intends to aim at the problem of oxygen content control on the basis of the prior art, especially using a specially improved crystal furnace, which can carry out high-temperature oxygen diffusion in the early stage of crystal growth, supplement oxygen content, and reduce oxygen defects; in the later stage of crystal growth Filling reducing gas or neutral gas to reduce the crystal can effectively balance the oxygen content, obtain high-quality LYSO crystal, and the success rate is greatly increased. At present, the important problem of domestic LYSO crystal is that the crystal yield is not high and it is easy to crack.

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