Study On The Preparation And Scintillation Properties Of Rare Earth Doped Gadolinium Aluminum Gallium Garnet Ceramics

Scintillation is a material that can convert high-energy particles into visible light.Therefore,it has huge application demands in geological prospecting,medical imaging,space physics and other fields.Among the numerous scintillating materials,Ce³⁺-doped Gadolinium Aluminum Gallium Garnet（Ce:GAGG）scintillating ceramics have attracted much attention for their special high density,fast attenuation and high light yield.In addition,co-doping method can effectively improve the scintillation property of the ceramics,so it is significant to research co-doped GAGG based scintillation ceramics.In this paper,the Ce³⁺and Ce³⁺/Pr³⁺doped GAGG powders were prepared by the co-precipitation method and analyzed.Then the Ce:GAGG and Ce,Pr:GAGG ceramics with great optical and scintillation properties were obtained by sintering the powders that prepared under the optimal process.The main contents are as follows:（1）The precursor was prepared by co-precipitation method,and the crystal transition temperature of the precursor was analyzed by thermogravimetry differential scanning calorimetry.The structure,morphology and chemical bond of the precursor were analyzed by X-ray diffraction,scanning electron microscope,infrared spectroscopy and other testing methods.The optimal preparation process of GAGG powder was explored.When the concentration of salt solution was 0.3mol/L,the concentration ratio of precipitant solution to metalion solution was 8:1,and the PH was equal to 8,the powder with the best structure and morphology could be obtained by calcinating at 900℃for 2h.On this basis,GAGG powders with different Ce³⁺doping amounts were prepared and the structure and morphology of Ce:GAGG powders were analyzed.The fluorescence spectra and fluorescence lifetime were used to characterize and analyze the effect of Ce³⁺doping concentration on the luminescence of the powders.The results show that when the doping amount of Ce³⁺is 0.5%,the luminescence intensity of the powder is the strongest.As the doping amount of Ce³⁺is further increasing,the luminescence intensity decreases,and the phenomenon of concentration quenching occurs.（2）Based on the preparation process of Ce:GAGG powder,Ce,Pr:GAGG powders were prepared by introducing Pr³⁺.The influence of the introduction of Pr³⁺on the structure and morphology of the co-doped powders were studied,and the luminescence properties of the Ce,Pr:GAGG powders were analyzed by fluorescence spectroscopy.The results show that when the doping concentration of fixed Ce³⁺is 0.5%and the doping concentration of Pr³⁺is 0.2%,the luminescence intensity of the powder is the strongest.The energy transfer efficiency between Ce³⁺-Pr³⁺was calculated by fluorescence lifetime,and the energy transfer mechanism between Ce³⁺-Pr³⁺was determined to be electric dipole moment-electric dipole moment effect.（3）The ceramic materials were obtained by dry pressing,cold isostatic pressing and atmospheric pressure sintering by using the Ce:GAGG and Ce,Pr:GAGG ceramic powders prepared under the best conditions as raw materials.By controlling the sintering system of ceramics including sintering temperature and sintering time,the grain size and pores of ceramics can be effectively regulated.The results show that the density,grain size and morphology of Ce:GAGG ceramics and Ce,Pr:GAGG ceramics that obtained as the temperature was 1700℃and the holding time was 20h are the best.The fluorescence lifetime test shows that the decay time of Ce:GAGG ceramics is 52ns,and the decay time of Ce,Pr:GAGG ceramics is 24ns.