| The thesis contains five chapters. Chapter 1 outlines the basics and working background of this thesis. Chapter 2 to chapter 5 introduced the synthesis of rare earth doped two kinds lutetium oxide functional nano-materials and transparent ceramic materials using two methods, and theirs microstructural and luminescent properties were analyzed and compared.In chapter 1, the introductions of rare earth functional materials, the basic principles of photoluminescence and the luminescence properties of trivalent rare earth ion luminescence are given. The researches, developments and achievements of nano-materials and transparent ceramics scintillator are stated at home and abroad. Two methods for the preparation of nano powders and transparent ceramics in this work are introduced in detail, and some impact factors on transparency of transparent ceramics are discussed.In chapter 2, Lu2O3:Eu3+ nano-particles and transparent ceramics were prepared by co-precipitation and solvo-thermal methods, respectively. XRD and FTIR results showed that the solvo-thermal treatment accelerated the crystallization of amorphous precursor and effectively decreased the crystallization temperature. XRD and SEM results showed that the precursor powders of Lu2O3:Eu3+ prepared by co-precipitation were amorphous with the rod structure about 200nm; the precursor powders of Lu2O3:Eu3+ prepared by solvo-thermal method mainly included nearly spherical particles with 50nm, whose main components were LuOOH, and the phase of Lu2O3 appeared at calcination temperature 400℃. The powder particle size, morphology and luminescence properties of the obtained Lu2O3:Eu3+ by co-precipitation and solvo-thermal were compared. The luminescence of the obtained Lu2O3:Eu3+ powders by co-precipitation under the different precipitation agents, different Eu3+ doped concentrations, different calcination temperature and calcination atmosphere was dicussed. The fluorescence decay curves of the obtained Lu2O3:Eu3+ powders at different calcining temperature and atmosphere were measured. The relations of fluorescence lifetimes and particle-size for powders were analyzed. The resultant Lu2O3:Eu3+ powders were pressed into tablets without any additives by dry-pressing moulding, sintered in vacuum and then nitrogen atmosphere at high temperature, and Lu2O3:Eu3+ transparent ceramics were obtained. The transparencies of the obtained Lu2O3:Eu3+ transparent ceramics under different conditions were compared, and some factors that affect the transparency of ceramics were analyzed.In chapter 3, the synthesis and luminescence properties of LuAG:Ce3+ nano-powders by solvo-thermal method were investigated. FTIR and XRD measurements showed that the precursor powders of LuAG:Ce3+ by solvo-thermal treatment, theirs main components were AlOOH, and cubic phase Lu2O3 appeared at calcination temperature 400℃, but that precursor powders prepared by co-precipitation were still amorphous at calcination temperature 800℃. The influences on the LuAG:Ce3+ powders morphologies under different precipitant, different volume ratio of ethanol and water, different calcination temperature were compared. Dependences of illumination intensity of LuAG:Ce3+ powders on Ce3+ concentration, the precipitation agents and the calcination temperature were discussed. The results showed that, the 1% Ce3+ doping concentration, ammonium hydrogen carbonate and ammonia water as mixture precipitation agent, under the calcination temperature 1000℃, the luminescence of the obtained LuAG:Ce3+ nano-powder was stronger. Emission spectrum of LuAG:Ce3+ phosphor was located at 450-650nm, including overlap of two broad emission bands, which was matched well with the sensitivity curve of silicon photodiode.In chapter 4, LuAG:Ce3+ nano-powders and transparent ceramics were obtained by co-precipitation and solvo-thermal method using ammonium hydrogen carbonate and ammonia water as a mixture precipitation agent, respectively. XRD, FTIR, SEM results showed that the prepared precursor powder of LuAG:Ce3+ by co-precipitation contained amorphous sheet structure, its main components were carbonate NH4A1(OH)2CO3 and Lu2(CO3)3 nH2O, but the obtained that by solvo-thermal method existed some octahedral shape material construction, whose main components were AlOOH and Lu(OH)3. In the same calcination conditions, the prepared LuAG:Ce3+ resultant powder by co-precipitation was almost spherical, well dispersed and uniform distribution with particle size about 80-100nm, and the obtained that by solvo-thermal method contains seriously agglomerative and irregular morphological particles with particle size about 30-50nm. The luminescence of the obtained LuAG: Ce3+ powder by solvo-thermal method was stronger than that of powder prepared by co-precipitation method. The luminescence properties of the obtained LuAG:Ce3+ powders by co-precipitation method at different calcination temperature and atmosphere were compared. The LuAG:Ce3+ powders prepared by above two methods were pressed into tablets without any other additives, calcined in the vacuum and then nitrogen calcinations, and the LuAG:Ce3+ transparent ceramics were obtained. The microsructures and transparencies of the obtained LuAG:Ce3+ transparent ceramics by above two methods were compared. Some specific impact factors that affected the transparency of ceramics were discussed. The excitation and emission spectra of the obtained LuAG:Ce3+ ceramics in two ways were analyzed. The luminescence of Ce3+ under the different excitation wavelengths was analyzed. LuAG:Ce3+ powders and transparent ceramics prepared by solvo-thermal method, their excitation and emission intensities were all stronger than that prepared by co-precipitation method, but the preparation process and cycle of solvo-thermal method was relatively long, and yields were relatively lower, so this solvo-thermal preparation process should be further optimized.In chapter 5, the precursor powders of LuAG:Ce3+ obtained by mixed solvo-thermal at 270℃for 2h were directly pressed into tablets, sintered in vacuum and then in nitrogen without any additive, and LuAG:Ce3+ transparent ceramics were synthesized. The luminescence in ultraviolet and vacuum ultraviolet region for LuAG: Ce3+ transparent ceramics was measured and investigated. The photoluminescence of LuAG:Ce3+ transparent ceramics under the different excitation wavelength was analyzed and luminescence mechanism for Ce3+ was discussed. The microstructures, transparencies and luminescence properties of the obtained LuAG:Ce3+ transparent ceramics in chapter 5 were compared with that in chapter 4. It was found that the prepared LuAG:Ce3+ transparent ceramic in chapter 5, its preparation process was simple, the transparency of ceramics was better and its luminescence was stronger relatively.
|
PDF Full Text Request