In Situ Precipitation Of CdS Quantum Dots In Transparent Media And Their Scintillation Properties

A scintillator is a light-to-light functional conversion material that can convert X-rays or other high-energy charged particles(such as?particles,?particles)into ultraviolet or visible light.At present,scintillators play a vital role in the fields of basic application research and radiation detection,and are widely used in high-energy physics,industrial non-destructive testing,materials research,and medical imaging.Therefore,traditional inorganic single crystals(such as Gd₂SiO₅:Ce³⁺,Cs I(Tl),Bi₄Ge₃O₁₂(BGO))have become commercial scintillator materials due to their structural stability and excellent optical scintillation properties.However,due to the complex preparation process of the single crystal,the time-consuming growth cycle,the high cost,and the prone to deterioration when exposed to water or high humidity,these many shortcomings limit the further development and use of single crystal scintillators.Glass-ceramic scintillators have attracted widespread attention due to their advantages of simple preparation,low cost,high transparency,and good physical and chemical stability.Therefore,the work of this thesis is mainly to grow CdS quantum dot(QD)crystallites in situ in a highly stable transparent glass medium,and to study the scintillation properties of CdS QD glass-ceramics,and finally explore the application in the field of X-ray imaging.The main research contents are as follows:(1)The process of in situ precipitation of CdS QD microcrystals from the amorphous glass matrix under the induction of high-energy electron beams was explored.In this experiment,high-temperature melting and post-heat treatment methods were used to successfully prepare glass containing SiO₂-B₂O₃-Zn O-Na₂O-K₂O-CdS precursors,and high-energy electron beams were used to replace the later heat treatment process.It was observed that with the irradiation time,the extension of the glass witnessed the process of the formation and growth of the QD microcrystals inside the glass from amorphous clusters to crystal nucleus.This phenomenon of electron beam-induced growth of QD microcrystals is mainly due to the increase in the temperature of the radiation site,which gives the energy required for nucleation and crystallization.In addition,the size of the crystallites is also closely related to the irradiation time.(2)The scintillation properties of CdS QD glass-ceramics are explored.First,through the heat treatment process,samples with different annealing temperatures were prepared,and a series of testing methods were used to explore the structure and optical properties of the samples.With the increase of the annealing temperature,the fluorescence intensity of CdS QD glass-ceramics shows a trend of first increasing and then decreasing,and reaches the strongest at 600?,and their fluorescence lifetime shows a change law similar to the fluorescence intensity.And take the best luminous sample to study its physical and chemical stability and scintillation performance.The results show that it has extremely high water and thermal stability.After being immersed in water for 30 days and heating and cooling for 3 cycles,the emission intensity can still be maintained respectively.It is 92%and more than 95%of the initial value.It has good scintillation luminescence performance under X-rays,and under high humidity,low dose(1 m Gy/s)and X-ray radiation up to 3600 s,X-ray The luminous intensity can still maintain more than 96%of the initial value.Finally,using the chip and ballpoint pen tip as imaging objects,using the built X-ray imaging system,the internal microstructure images of the two objects were taken with a digital camera with a resolution of up to 10 lp/mm.(3)Explore the recoverable performance of CdS QD glass-ceramics scintillator under high dose(8 m Gy/s)X-ray irradiation for a long time.By testing a series of data characterizations such as XRD patterns,photoluminescence spectra,X-ray luminescence spectra of the original and damaged samples,it is proved that under long-term and high-dose X-ray irradiation,the simple method of low-temperature annealing can make the optical and scintillation properties of CdS QD glass-ceramics recovered to more than 97%of the initial value.The research results show that CdS QD glass-ceramics is a promising scintillator material,which can be used in X-ray imaging and industrial flaw detection.