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CN-122013294-A - LYSO crystal preparation process

CN122013294ACN 122013294 ACN122013294 ACN 122013294ACN-122013294-A

Abstract

The invention discloses a preparation process of LYSO crystals, which relates to the technical field of preparation of scintillation crystal materials, and comprises the following steps of preparing LYSO precursors by a liquid phase method, growing LYSO crystal samples by a crucible descending method, carrying out heat treatment and sectional annealing treatment on the LYSO crystal samples to obtain LYSO crystals, wherein the LYSO crystals prepared by the process have few oxygen vacancies, high transparency and strong light output, and the crucible material used in the process steps is a calcium oxide stabilized zirconia crucible, so that the instrument cost is greatly reduced.

Inventors

  • LUO YI
  • GONG RUI
  • ZHAO JIANHUA
  • YU JIE

Assignees

  • 安徽科瑞思创晶体材料有限责任公司
  • 昆明理工大学

Dates

Publication Date
20260512
Application Date
20260120

Claims (6)

  1. 1. A process for preparing a LYSO crystal, comprising the steps of: S1, putting raw materials into a reaction tank, heating and stirring for 4-6 hours, dripping a mixed solution into the reaction tank, aging overnight, alternately washing with deionized water and absolute ethyl alcohol, and drying to obtain a LYSO precursor; S2, placing the LYSO precursor into a crucible, placing the crucible into a reaction furnace, growing crystals by a crucible descent method, heating to 600-700 ℃ at a heating rate of 100 ℃ per hour, heating to the melting of the LYSO precursor at a heating rate of 80 ℃ per hour, starting to grow crystals, keeping the temperature until the crystal growth is finished, and cooling to room temperature at a cooling rate of 60 ℃ per hour to obtain LYSO crystal samples; S3, placing the LYSO crystal sample into a vacuum furnace, vacuumizing, introducing reducing gas, heating to 600-700 ℃ at a heating rate of 100 ℃ per hour, performing heat preservation and heat treatment for 3-5 hours, introducing oxidizing gas, replacing the original atmosphere, heating to 1400-1500 ℃ at a heating rate of 50 ℃ per hour, annealing for 10 hours at a cooling rate of 100 ℃ per hour, cooling to 1200-1300 ℃ for 10-20 hours, and cooling to room temperature at a cooling rate of 60 ℃ per hour to obtain the LYSO crystal.
  2. 2. The process for preparing LYSO crystals according to claim 1, wherein the LYSO crystals comprise Lu 2 O 3 、Y 2 O 3 and CeO 2 in a weight ratio of 85-90:5-10:0.3-0.5.
  3. 3. The process for preparing LYSO crystals according to claim 1, wherein the mixed solution in S1 is a mixed solution of sodium silicate and ammonia water, and the mass ratio of the added solution to the mixed solution is 1:5-6; the adding mass ratio of the raw materials to the mixed solution is 101-103:100.
  4. 4. The process for preparing LYSO crystals according to claim 1, wherein the crucible in S2 is a calcium oxide stabilized zirconia crucible.
  5. 5. The process of claim 1, wherein the reducing gas in S3 is a mixture of 95% N 2 /Ar and 5%H 2 and the oxidizing gas is a mixture of 97% N 2 /Ar and 3%O 2 .
  6. 6. The process for preparing a crystal of LYSO according to claim 1, wherein the chemical composition of LYSO crystal is Ce 2x (Lu 1-y Y y ) 2(1-x) SiO 5 , where x is 0.00001 to 0.05 and y is 0.0001 to 0.9999.

Description

LYSO crystal preparation process Technical Field The invention relates to the technical field of preparation of scintillation crystal materials, in particular to a preparation process of LYSO crystals. Background Lutetium yttrium silicate crystals (LYSO: ce) are novel high-performance scintillation materials developed in the last decade, the chemical formula of the lutetium yttrium silicate crystals is Ce 2x(Lu1-yYy)2(1-x)SiO5, LYSO crystals are monoclinic systems with a space group of C2/C, ce 3+ is taken as a luminescence center, and when high-energy rays (gamma/X rays) excite the crystals, energy is transferred to Ce 3+ ions through crystal lattices to trigger 5 d-4 f energy level transition of the crystals, so that ultra-fast scintillation fluorescence is generated. Lutetium provides high density and high effective atomic number, enhances the radiation blocking capability, and yttrium can adjust lattice distortion to optimize Ce 3+ luminous efficiency. LYSO crystals have high density (7.1 g/cm 3), high effective atomic number (average Z=64), excellent energy resolution (less than 10% @662keV under Na-22 source), fast luminescence attenuation (about 40 ns), high light output (more than or equal to 30000 ph/MeV), low afterglow (less than 0.1% @3 ms) and other characteristics, and can be widely applied to the fields of nuclear medicine imaging PET, high-energy physical detection, security inspection equipment and the like. Currently, LYSO crystals have a problem of light output variation, and related studies hypothesize that the purity of the starting lutetium oxide is insufficient or that oxygen vacancies are present in the crystals. In the prior art, most of the Chinese patent with the application number of CN201410532109.X adopts an iridium crucible to resist the high corrosiveness of molten raw materials, a process for growing cerium-doped yttrium lutetium silicate scintillation crystals by using the molybdenum crucible is disclosed, the iridium crucible is replaced by the molybdenum crucible to reduce the high-volume instrument cost, a crucible descent method is adopted, meanwhile, weak reducing gas is introduced in the heating of the molten raw materials and the crystal growth stage, and a carbon felt is added in a hearth of a vacuum furnace to prevent the molybdenum crucible from being oxidized and corroded, but the crystals grow in the weak reducing atmosphere to cause more oxygen vacancies and poor light output performance, and the Chinese patent with the application number of CN201510761927.1 discloses a method for improving the scintillation performance of the cerium-doped yttrium lutetium silicate crystals grown by the crucible descent method, and the grown crystals are subjected to heat treatment under the mixed gas of nitrogen and oxygen to compensate the oxygen vacancies, but the method oxidizes part of Ce 3+ to 4+ to cause poor light output performance. New designs and optimizations of the process steps are needed to address the problem of light output differences in LYSO crystals. Disclosure of Invention The invention aims to provide a preparation process of LYSO crystals, which solves the following technical problems: The problems of oxygen vacancy and Ce 3+ oxidation prevention of LYSO crystals in the existing crucible descent method technology are difficult to perfectly solve at the same time, and the economical efficiency and the practicability are difficult to ensure at the same time in the selection of crucible materials. The aim of the invention can be achieved by the following technical scheme: A process for preparing a LYSO crystal, comprising the steps of: S1, putting raw materials into a reaction tank, heating and stirring for 4-6 hours, dripping a mixed solution into the reaction tank, aging overnight, alternately washing with deionized water and absolute ethyl alcohol, and drying to obtain a LYSO precursor; S2, placing the LYSO precursor into a crucible, placing the crucible into a reaction furnace, growing crystals by a crucible descent method, heating to 600-700 ℃ at a heating rate of 100 ℃ per hour, heating to the melting of the LYSO precursor at a heating rate of 80 ℃ per hour, starting to grow crystals, keeping the temperature until the crystal growth is finished, and cooling to room temperature at a cooling rate of 60 ℃ per hour to obtain LYSO crystal samples; S3, placing the LYSO crystal sample into a vacuum furnace, vacuumizing, introducing reducing gas, heating to 600-700 ℃ at a heating rate of 100 ℃ per hour, performing heat preservation and heat treatment for 3-5 hours, introducing oxidizing gas, replacing the original atmosphere, heating to 1400-1500 ℃ at a heating rate of 50 ℃ per hour, annealing for 10 hours at a cooling rate of 100 ℃ per hour, cooling to 1200-1300 ℃ for 10-20 hours, and cooling to room temperature at a cooling rate of 60 ℃ per hour to obtain the LYSO crystal. As a further scheme of the invention, LYSO crystals comprise Lu 2O3、Y2O3 and CeO 2 in a