The Growth And Luminescence Properties Of MY₂Cl₇:Ce(M=Cs,Rb) Complex Rare-earth Halide Scintillation

Recently,the crystal of rare earth halides has attracted more and more attention in scintillation optics due to their high light yield,fast response,excellent energy resolution and very good timing characteristics.The light output of these crystals is in the range of 30000-80000 ph/Me V,the energy resolution is in the range of 3.0%?7.0%(@662 ke V),and the decay time is in the range of20?50 ns.The new rare-earth halide scintillation crystals are mainly classified into single rare-earth halides(REX₃)and alkali metal rare-earth halides.When Ce³⁺ions are incorporated into the composite rare earth halide matrix,scintillation crystals with excellent properties can be prepared.The crystal radiation transition mechanism is mainly used to detect high-energy rays such as X-rays,gamma rays,and high-energy particles such as alpha particles.In this thesis,two new scintillators CsY₂Cl₇:Ce and RbY₂Cl₇:Ce based on the MY₂Cl₇:Ce system were studied.The Bridgman-Stockbarger method was used to successfully grow in a sealed quartz crucible.The scintillation properties were measured.The properties of synthesizing such crystals were discussed Advantages,the main research work is as follows:1.CsY₂Cl7:Ce crystals raw material pre-treatment and polycrystalline material synthesis,crystals growth and sample phase performance and scintillation performance characterization.Polycrystalline materials were synthesized by high-temperature solid-phase method using Cs Cl,YCl₃and CeCl₃powders with a purity of above 99.99%and anhydrous as raw materials.The Bridgman-Stockbarger method was used to successfully grow the crystals.Most of the crystals were transparent,with a small number of cleavage planes.CsY₂Cl₇:Ce crystals with length of 9mm and width of 6 mm were obtained by dissociating the transparent part.Obtained by powder XRD analysis the crystal of CsY₂Cl₇:Ce crystallizes in orthorhombic structure and the cell parameters were determined to be:a=12.7469(?),b=6.9302(?),c=12.6655(?),Z=4.Observing the DTA curve,the melting point of the CsY₂Cl₇crystal is 622?.The photoluminescence spectrum of CsY₂Cl₇:Ce showed emission band centered at around 390nm and excitation band centered at around 335 nm,this phenomenon respectively correspond to the Ce³⁺ electron transition from 4F orbit transition to T_2g and E_g energy levels in 5d orbit.and X-ray excitation emission spectra have peak positions at approximately the same 390 nm emission peaks.The energy resolution of the resulting gamma-ray peak at 662 ke V was ¹8.7% under ?-ray excitation of ¹³⁷Cs source,and the gamma ray excitation scintillation decay time of about ²0 ns.2.RbY₂Cl₇:Ce crystal raw material pre-treatment and polycrystalline material synthesis,crystal growth and sample phase performance and scintillation performance characterization.Polycrystalline materials were synthesized by high-temperature solid-phase method using Rb Cl,YCl₃and CeCl₃powders with a purity of above 99.99%and anhydrous as raw materials.The Bridgman-Stockbarger method was used to successfully grow the crystals.Most of the crystals were transparent,with a small number of cleavage planes.RbY₂Cl₇:Ce crystals with length of 10mm and width of 5 mm were obtained by dissociating the transparent part.Obtained by powder XRD analysis the crystal of RbY₂Cl₇:Ce crystallizes in orthorhombic structure and the cell parameters were determined to be:a=13.354(?),b=6.967(?),c=7.922(?),Z=4,Dx=3.151g/cm³.Observing the DTA curve,the melting point of the RbY₂Cl₇crystal is 617?.The photoluminescence spectrum of CsY₂Cl₇:Ce showed emission band centered at around 389 nm and excitation band centered at around 336 nm,this phenomenon respectively correspond to the Ce³⁺electron transition from 4F orbit transition to T_2g and E_g energy levels in 5d orbit.and X-ray excitation emission spectra have peak positions at approximately the same 390 nm emission peaks.The energy resolution of the resulting gamma-ray peak at 662 ke V was?9.8%under?-ray excitation of ¹³⁷Cs source,and the gamma ray excitation scintillation decay time of about?35 ns.RbY₂Cl₇:Ce crystal has better performance than CsY₂Cl₇:Ce crystal.