铕掺杂Gd_(2)Zr_(2)O_(7)透明陶瓷的制备及闪烁性能

Preparation and Scintillation Properties of Europium-Doped Gd_(2)Zr_(2)O_(7)Transparent Ceramics

与传统闪烁陶瓷相比,基于立方相Gd_(2)Zr_(2)O_(7)具有高密度、高光学透过率和良好的闪烁性能等特征,本工作采用真空烧结法,成功制备出系列Eu3+掺杂Gd_(2)Zr_(2)O_(7)透明陶瓷,研究了掺杂离子及掺杂量对其晶体结构、光学透过率、荧光性能及闪烁性能的影响。结果表明,所制备的透明陶瓷样品具有良好的光透过能力;光谱表征发现,20%Eu^(3+)掺杂Gd_(2)Zr_(2)O_(7)具有最佳的光致荧光和辐照发光强度,其最强发射峰位于630 nm。X射线成像实验表明,Gd_(1.8)Eu_(0.2)Zr_(2)O_(7)透明陶瓷的X射线成像分辨率可达11 lp·mm^(-1),具备对不同材质物体的成像应用潜力。在医学成像、工业探伤、高能物理等领域具有潜在的应用价值。

Introduction This paper prepared a series of Eu ^(3+)doped Gd_(2)Zr_(2)O_(7) transparent ceramics by a vacuum sintering method,and charaterized the density and optical transmittance of cubic phase Gd_(2)Zr_(2)O_(7).The effects of doping ions and their concentration on the crystal structure,optical transmittance,fluorescence performance,and scintillation performance were investigated.The results show that the prepared transparent ceramic samples have a good optical transmittance.The spectral characterization reveals that 20%Eu ^(3+)doped Gd_(2)Zr_(2)O_(7) has optimum fluorescence and irradiated luminescence intensity,and the most intense emission peak is located at 630 nm.The X-ray imaging shows that Gd_(1.8)Eu_(0.2)Zr_(2)O_(7) transparent ceramics have an X-ray imaging resolution of up to 11 lp·mm^(–1),having a potential for the imaging applications.Methods High purity gadolinium oxide,europium oxide and zirconia(purity 4N)as raw materials were mixed according to a stoichiometric ratio(Gd ^(3+),Eu ^(3+)):Zr^(4+)of 1:1.The mixed raw materials were ground in anhydrous ethanol and polyethylene glycol(PEG)in a planetary mill with zirconia grinding chamber and ballsat a ball:material mass ratio of 27:1 for 72 h.Afterwards,the ground mixture slurry was washed with anhydrous ethanol after drying.Gd_(2–x)Eu_(x)Zr_(2)O_(7) could be obtained via sintering in a box furnace at 1400℃ according to the reaction:Gd_(2–x)Eu_(x)Zr_(2)O_(7)(1-x/2)Gd_(2)O_(3)+2ZrO_(2)+x/2Eu_(2)O_(3)→Gd_(2-x)Eu_(x)Zr_(2)O_(7)(x=0-0.28)The ceramic blank was formed via dry pressing and cold isostatic pressing,sintered in a vacuum tungsten furnace at 1800℃ for 10 h,and then annealed in a box furnace in air at 1250℃ for 6 h.Finally,a transparent ceramic with 1 mm thickness was obtained after double-sided polishing.Results and discussion A ceramic powder prepared by ball grinding was sintered in a vacuum tungsten wire furnace to prepare transparent ceramics with a high light transmission rate.The XRD results show that when 20%Eu ^(3+)is added to Gd_(2)Zr_(2)O_(7),the crystal structure of Gd_(1.8)Eu_(0.2)Zr_(2)O_(7) appears some superlattice diffraction peaks(331)of pyrochlore.The crystal structure changes from defective fluorite to pyrochlore.The optical transmittance spectra indicate that the optical transmittance decreases from 76%to 65%(@1500 nm)when the doping content of Eu ^(3+)increases from 0 to 28%.There exist 6 distinct excitation peaks between 230 nm and 500 nm.A wide excitation peak at 267 nm is attributed to the charge transfer band of O^(2-)-Eu^(3+).In addition,five excitation peaks at 362,382,393,414 nm and 465 nm correspond to 4f-4f energy level transitions ^(7)F_(0)→^(5)D_(4),^(5)G_(J),^(5)L_(6),^(5)D_(3) and ^(5)D_(2) in Eu^(3+),respectively.Among six excitation peaks,a wide excitation peak at 267 nm has the most intense intensity.All the excitation peak intensities increase when Eu^(3+)concentration increases from 4%to 20%.When Eu^(3+)doping amount is 20%,the maximum excitation peak intensity appears.The further characterization of the scintillation properties of ceramic samples indicates that the X-ray irradiation intensity is a maximum value when the doping amount is 20%.At 630 nm,the radiation luminescence intensity value is 1.1×10^(4),and the material has an X-ray absorption capacity equivalent to that of BGO crystals,and also has a good anti-radiation damage ability.Finally,X-ray imaging tests on Gd_(1.8)Eu_(0.2)Zr_(2)O_(7) ceramic samples of different materials show that the Gd_(1.8)Eu_(0.2)Zr_(2)O_(7) ceramic sample can clearly distinguish metal and plastic materials,and has a limit spatial resolution of 111p·mm^(–1),indicating that the modified material is a potential X-ray detection material.Conclusions A series of Eu^(3+)doped transparent ceramics were prepared by a vacuum sintering method.The crystal structure of Gd_(2–x)Eu_(x)Zr_(2)O_(7) was gradually changed from defective fluorite to pyrochlore via adjusting the doping amount of Eu^(3+).At 630 nm,the Gd_(2–x)Eu_(x)Zr_(2)O_(7) transparent ceramic sample showed the optimum fluorescence emission and X-ray irradiation intensity,and the material had a limit spatial resolution of 111p·mm^(–1),which could clearly distinguish metal and plastic materials,confirming an application potential of the A_(2)B_(2)O_(7) series of scintillating transparent ceramics X-ray imaging.