Study On Optical Properties Of Rare Earth Ion Doped High Density Scintillating Glasses And Fiber

Radiation detection is a kind of technique for ionizing radiation and high energy particle detection.Since the discovery of X-ray,many kinds of detectors have been designed,such as gas chamber detector,scintillation detector,semiconductor detector,etc.Scintillation detectors,as one of the important radiation detectors,are widely used in high energy physics,atomic energy,medicine and safety.Scintillator has an important effect on the performance of the detector.Scintillators,as a kind of material capable of converting radiation to visible light,need to have the characteristics of high density,high light yield and fast decay.At present,the scintillators are mainly concentrated in single crystals and phosphors.There are few studies on scintillating glass and fibers,and their performance in various aspects remains to be further improved.This thesis introduces the luminescence principle and performance requirements of scintillators,and the research progress,applications and problems of glass scintillators in recent years are summarized and reviewed,the future research direction is summarized and prospected.On this basis,we obtained high density scintillating glass with good transparency through the design and optimization of glass composition.The specific nanocrystalline phase was precipitated by heat-treatment,the luminescence property was improved effectively.At the same time,a scintillating glass fiber was designed to connected with a commercial silica fiber for optical transmission.The main research results and conclusion are as follow:1.The crystallization behaviors and spectral properties of silicate glasses were studied.It was found that there is a phase transition from Gd₃TaO₇ to M'-type GdTaO₄ nanocrystalline phase with the increase of heat-treatment temperature.By controlling the heat-treatment temperature,the glass-ceramics with different nanocrystalline phases can be obtained.In addition,the unique self-limiting crystallization characteristic helps to suppress the abnormal growth of crystal grains during phase transformation.As a result,transparent glass-ceramics with high crystallinity can be obtained.Furthermore,a high efficient energy transfer between Gd³⁺ions and[TaO₄]^3-groups to luminescent centers was observed and it greatly improves the luminescence property of glass-ceramics.2.The crystallization behaviors and spectral properties of high density tungstate glass were studied.It was found that adding a small amount of B₂O₃ can effectively improves the glass forming performance.The density of the obtained glass reached 6.26⁶.31 g/cm³,which is equal to that of single crystal Lu₂Si₂O₇.By controlling the heat-treatment temperature,Gd₂?WO₄?₃ crystalline phase was precipitated in the glass.A high efficient energy transfer from Gd³⁺ion and[WO₆]^6-group to luminescent centers was observed and it helps to enhance the light harvesting ability of the matrix,resulting in the improving luminescence property of glass-ceramics.3.The Lu₂SiO₅ scintillating glass fiber with core-cladding configuration was fabricated by melt-in-tube method.The structure characterizations show that the core layer transforms from crystal state to amorphous state after high temperature drawing.The spectroscopic characterizations indicate a notable blue shift of the excitation and luminescence spectrum.The scintillating glass fiber was connected to the commercial silica fiber and the optical properties of the connected fiber system were studied.The constructed system can be potentially applied for remote detection.