The Optical Properties Research Of New LuAG Phase Nano-Powders And Flashing Ceramic

With the rapid development of optoelectronic science and technology, photoelectric sensordetection technology more and more widely applied to the military, communications, industrial,medical, scientific and other fields. Currently, the main work material of photoelectric sensor issingle crystal and glass. However, the single crystal growth methods and physical properties ofglass limits the application of optical sensor leads to its performance cannot be played fully. Suchas restrictions on the laser potential output power, so polycrystalline ceramic which is expected tobecome the main work material of the next generation of solid photoelectric sensors.In recent years, a series of transparent ceramics have been developed, including oxideceramics, such as Al₂O₃, Y₂O₃, TiO2etc, and non-oxide ceramics, such as ZnS, MgF₂, AlN etc. InJapan, Osaka University and Krosaki company successfully prepared the YAG: Nd ceramics usedto produce laser output, YGO, Gd2O2S flashing ceramic successfully used in medical X-CT byJapan’s Hitachi, Germany’s Siemens and other companies.So far, most of flashing ceramic is still in trials, in order to apply flashing ceramics to industry,all aspects of which including luminescence mechanism, preparation process and dopingtechnology must be researched in detail. While good performance of the flashing ceramic requiresits raw material ceramic powder must have high purity, uniform powder particles, good dispersionand high sintering activity, etc., so the choice of nano-powder preparation process is an importantfactor to flashing ceramic properties.Lutetium aluminum garnet (Lu₃Al₅O₁₂, LuAG) and lutetium terbium aluminum garnet（LuxTb3-xAl5O12,（LuTb） AG） polycrystalline ceramics with good physical and chemical properties,high doping performance, and many other advantages, is expected to be widely used. The nano-powder and ceramics of LuAG phase was researched in this paper. The main contents include:1)the research of new ultrasonic spray coprecipitation process;2) The research of powders calciningtechnology and ceramic molding process,3) The research of Ce³⁺and Eu³⁺ions’ the opticalproperties in LuAG and （LuTb）AG powder and ceramics.In chapter one, we presented the characteristics and research progress of nano-powders andflashing ceramics, then summarized the preparation technology of which. The rare earth ions’characteristics and applications were introduced, and the basic theories such as J-O theory wereintroduced as well. In chapter two, Ce³⁺-doped LuAG ultra-fine nano-powder were fabricated by the newultrasonic spray coprecipitation process, the impact of different temperatures on the synthesis ofnano-powder particles was researched, and the optimum calcination temperature was determined.Analyzed the level transition and fluorescence curve of different concentrations of Ce³⁺ions inLuAG powder, and determined the optimal doping Ce³⁺ion concentration too.In chapter three, Eu³⁺-doped LuAG ultra-fine nano-powder were fabricated by the newultrasonic spray coprecipitation process, the level transition and fluorescence curve of differentconcentrations of Ce³⁺ions in LuAG powder were analyzed. Intensity parameters t（t=2,4） ofisotropic nano-powder were calculated by J-O theory, and then obtained phonon-side bandspectrum of LuAG:Eu³⁺nano-powder excited by7F0-5D2leaps. The results shows the optimaldoping Eu³⁺ion concentration in LuAG powder is about⁵mol%, intensity parameters of powderwill increase slightly as the doping concentration increased, while electron-phonon couplingweakened slightly. Powder intensity parameters2is about0.15×10-20cm2,4is about0.12×10-20cm2.In chapter four, Eu³⁺-doped （LuTb）AG ultra-fine nano-powder were fabricated by the newultrasonic spray coprecipitation process. The energy level transition of Eu ions and Tb ions ofsamples were analyzed in detail. Intensity parameters2and4of Eu³⁺were obtained by using J-O theory, the result shows that Eu³⁺ion7F0-5Dj（j=0,1,2） excitation peak cannot be observed forwhich overlapped with the excitation peak of Tb3+. Intensity parameter2of powder will increaseslightly as the doping concentration of Eu³⁺increased, Eu-O bond strength and the covalent ofsystem increased, while symmetry reduced slightly.In chapter five, LuAG flashing ceramic were prepared by vacuum sintering process. Surfacetopography and fluorescence effects of LuAG ceramic were observed, and Intensity parameter2and4were calculated as well. The result shows that long time calcination to nano-powders canpromote crystallization and evolved into flashing ceramics. Compared to the LuAG nano-powder,LuAG:Eu ceramic fluorescence has more intense fluorescence peak and a narrower FWHM.Fluorescence effect of Eu³⁺greatly enhanced, the covalent of system reduced, while symmetryenhanced obviously.