The Synthesis And Spectral Properties Of Ce:YAP Crystal And Ce:YAG Nanophosphor

Recently, the development of technique requires better scintillation single crystal. Scientists are focusing on finding crystals with high light output and rapid response time. High temperature crystal Ce:YAP has good mechanical process properties, stable chemical character and good detecting properties. All these characters make it a promising scintillator in many fields. From successfully invented in the 1990s, white LEDs has attracted research interest of many countries and been used in many fields for its high-efficient, low-energy loss and pollution-free merits .So there are extensive studies on the synthesis of YAG powder which is one of the key techniques to LEDs.In this paper, the major work is to study the optical properties of YAG and YAP doped with cerium. The species and distributions of the defects in the crystal are analyzed, which will provide useful spectral information for decreasing the defects and improving the properties of the crystal.This paper is composed of the five chapters. In the first chapter, the developing progress and focus of the research of alumina-yttria were summarized. And the luminescence mechanism and basic nature of the scintillator were introduced.In the second chapter ,we investigated the absorption spectrum,emission spectrum and excitation spectrum of Ce:YAP ,and analysed the influence on spectra of the doping concentration, anneal atmosphere, crystal orientation and the depth .The emission and excitation spectra at various temperatures are measured. The energy transfer excited by different wavelengths and color centres are discussed.In the third chapter, with nitrates as materials and citric acid as the complexant in experiment, YAG powders were synthesized by sol-gel method in the range of 35%-40% Y₂O₃. The precursors and powders sintered at different temperatures were characterized by thermogravimetry/differential thermal analysis(TG/DTG), x-ray diffractormetry(XRD), Fourier transform infrared spectroscopy (FT-IR), Transmission electron microscope(TEM) and so on. The impact factors are analyzed.In the fourth chapter, Ce :YAG nanophosphors were synthesized with nitrates as materials and citric acid by a gel combustion method. The properties of phosphor was characterized by XRD , FTIR and TEM. The spectral properties were measured by UV-VIS-NIR spectrophotometer. The spectral intensity changed doing with the concentration of Ce.Finally, all results in the thesis are outlined, and it is suggested that the further work should be done in the following stage.