Preparation And Property Study Of Terbium Aluminumgarnet Based Ceramic Scintillator Powders

Terbium aluminium garnet(Tb₃Al₅O₁₂,TAG)based ceramic scintillator could be used in the fields of high energy physics,nuclear medicine,geological exploration and safety inspection,based on its high density,good radiation resistance,high light output and Short decay time.The preparing of TAG scintillation crystal was limited by its defects as harsh growth conditions,long preparation cycles,high production instrument requirements,high cost,limited size and inhomogeneity of doping ions,which could be the biggest limitation of its application.So it was of great significance in developing and preparing TAG polycrystalline ceramic scintillators.As the first step in preparing polycrystalline ceramic scintillators,the raw materials of TAG nano powders used for the preparation of ceramic scintillators must to be high purity,good dispersibility,uniformity and good sintering activity,At present,there were many defects in the preparation of TAG powder,such as poor dispersion,uneven particle size and high activation energy barrier,which lead to the higher sintering temperature and lower fluorescence intensity,this has brought a great limit to the following preparation.In addition,the specific reaction process for the preparation of TAG powder was also lack of investigation.In order to decrease the sintering temperature,TAG powders were prepared by sol-gel method and co-precipitation method.Through the characterization of the prepared powders,compared with the co-precipitation method,the crystallization temperature of TAG phase prepared by sol-gel method could be reduced to 920?,and the final fluorescence intensity was also higher than the co-precipitation method by 30%.It could be seen that the sol-gel method has more advantages in the preparation of TAG powder.From the atom diffusion velocity angle,through the optimization of process parameters of sol-gel method,the microstructure was optimized by increasing the amount of citric acid which provide a channel for short-range diffusion of atoms,improve the diffusion rate for each phase of the crystallization,thus reducing the sintering temperature.Under the optimal conditions,TAG powder has good dispersion and uniformity which brings good sintering activity,the crystallization temperature of TAG was reduced to 877.5?and the fluorescence intensity increased by about 32%.At the same time the specific reaction process for the preparation of TAG powder was investigated.From the point of activation energy of nucleation,the activation energy barrier of nucleation was reduced by introducing metal ions,and the sintering temperature of TAG powder was further reduced.The Fe³⁺ ions were added into the TAG system for the first time,and it was found that the Fe³⁺ ions could be the preferential nucleation sites,which could reduce the activation energy of the nucleation and further improve the sintering activity.Under the optimum conditions of Tb₃(Al_0.95,Fe_0.05)₅O₁₂,the crystallization temperature of the TAG phase could be reduced to 780?,but the introduction of Fe³⁺ ions reduces the fluorescence intensity of TAG system to some extent.Therefore,in order to overcome the defects of Fe³⁺ in the system,Ce³⁺ ion was introduced as its highly vibration intensity.Based on this,a newly type of ceramic scintillator powder was prepared,compared to undoped one,the optimal composition was Tb_2.97(Al_0.95,Fe_0.05)₅O₁₂:Ce_0.03 and the fluorescence intensity was increased by 1 times.