Design,Preparation And Properties Of Scintillation Glass And Composite Film For X-ray Imaging

X-rays have been widely used in nuclear physics,medical diagnostics and industrial non-destructive testing due to their excellent detection capabilities.Scintillators,as a key part of this,present various challenges such as improving absorption,light yield and stability.In particular,scintillation films applied to X-ray imaging play the role of providing high spatial resolution.Rare-earth ion-doped inorganic scintillators,as a more mature and feasible solution in the field of high-energy ray detection at this stage,have gained a lot of experimental proof.However,their application in the field of X-ray imaging requires further improvements in preparation process,processing thickness,optical yield,efficiency,etc.In this thesis,the optical and scintillation properties of Tb³⁺-doped fluorosilicate glasses and Lu AG:Ce-PDMS composite films are investigated,and the performance of these materials in X-ray imaging is further investigated as follows:（1）In response to the demand for high light yield and high transparency of scintillators for X-ray imaging,a Tb³⁺-doped fluorosilicate glass component was designed based on the luminescence peak position of rare-earth ions in the glass network and the response range of CCD detectors,and prepared by the conventional melt-quenched cooling method.With the specially designed glass fraction,it shows an extremely high quantum efficiency（95.44%）,thus improving the scintillation light yield.Under X-ray excitation,it exhibits strong narrow-band emission peaking at 542 nm with about 58%of the total number of photons,with the peak located near the wavelength where Si PM shows the maximum PDE（32.5%@550 nm）.In the range of 300-800 nm,the XEL integrated intensity of Tb³⁺-doped fluorosilicate glass is 243%of that of a commercial Bi₄Ge₃O₁₂ single crystal of the same thickness,with a measured spatial resolution of 166 lp/mm.The experimental results indicate that Tb³⁺-doped fluorosilicate glass is expected to be used as a scintillator in indirect type due to its high scintillation light yield,unrestricted size and low cost.X-ray imaging equipment.（2）Lu AG:Ce nanopowders were prepared by citrate sol-gel combustion method.The effects of different heat treatment conditions on the microstructure and luminescence properties of Lu AG:Ce nanopowders were investigated.The phase composition,morphology and luminescence properties of the obtained materials were characterized by X-ray diffractometer,transmission electron microscope and blue light excitation photoluminescence,respectively.The results showed that the emission intensity of the Lu AG:Ce nanopowders gradually increased with the increase of the heat treatment temperature and the increase of the heat treatment time.In addition,the average particle size of the Lu AG:Ce powder under the heat treatment condition of 2h at 850℃ was 40 nm,which was favorable for the uniform dispersion in the organic polymer.（3）In response to the demand for high optical yield and high absorption of scintillator films for X-ray imaging,organic-inorganic composite scintillators with a thickness of 100μm were prepared by mixing Lu AG:Ce nanopowders of different mass fractions（60-90 wt.%）with PDMS.The XEL intensity of the Lu AG:Ce（90 wt%）-PDMS composite film with a thickness of 100μm was about286%of that of the BGO crystal in the wavelength range of 300-700 nm,and the measured spatial resolution was 25 lp/mm.The experimental results showed that the indirect X-ray detector composite film based on the Lu AG:Ce-PDMS composite film also has excellent X-ray imaging capability,providing a solution to some of the current challenges in X-ray medical imaging and industrial inspection.