Researches And Theoretical Calculations On (Oxo)nitridosilicate Phosphors

With the development of energy crisis and environmental pollution, the lighting and display area has attracted more and more attention for they constitute a large partial in the total energy consumption. The new green and ecconomic techniques have been considered to be the only way to solve this problem. In recent decades, the LED (Light emitting diodes) and PDP (Plasmon display panels) have been getting more advances due to their advantages compring with traditional lighting and display techniques. For examples, LED is famous for its small volume, low energy consumption, high color purity and excellent color index and the PDP generally considered to main technique for the large-screen and3D display techniques. What’s more, the LED and PDP could easily be realized in mass production for their simple configuration. Therefore, considering the environmental, energetic and economic elements, the new luminescence and display techniques will attract much more attentions and take an important part in future.The luminescence converting materials play important roles for they are irreplaceable in realizing different color and the high quality in the LED and PDP techniques. The phosphors used in the LED and PDP systems should have short response time, long wavelength excitation and emission spectra, high quantum efficiency and excellent stabilities under high current and temperature. While the traditional phosphors could not fulfill these demands for their low stabilies, so it is very necessary to exploit novel phosphors.The (oxo)nitridosilicate phosphors are considered to be the host materials due to their high structural and chemical stabilities and have been used as engine and fire resisting materias, such as a-SiAlON ceramics. In recent years, they have been used as the host materials for rare earch doped phosphors due to their superior mechanical stabilities and chemical interness. Therefore, it is meaningful to study the properties and synthesis of these phosphors.This paper is divided into6chapters:Chapter1of this manuscript briefly introduced the development history of luminescence and display techniques, and explained some basic concepts about the colorimetry.Chapter2is the experimental and characteristic sections. We have listed the raw materials, experimental and theoretical simulations methods, characteristic techniques used in this manuscript.In Chapter3, the optical properties and luminescence mechanism of the Ba3Si6O12N2:Eu2+green phosphors were systematically studied, including. First we had synthesized the Ba3Si6O12N2:Eu2+green phosphors and investigated the effects of temperature, codoping concentration and flux on the excitation and emission spectra. Then we theoreticatically calculated the band structure, density of states and absorption spectra by the first principle method.In Chaper4we fabricated a BaSi3Al3O4N5:Eu2+new blue emitting phosphors for the PDP and LED application and resolved its structure information by Rietveld method. This phosphor had a monoclinic system with space group of P21/m. The phosphor could be efficiently excitied from VUV to near UV region, and showed excellent chemical stability, thermal interness and acid resisting properties. The particle size could be easily adjusted by the amount of BaF2flux in the raw materials.In Chapter5, a convient method used to fabricate the spherical oxonitridosilicate phosphors with high packing density in the LED and PDP techniques were introduced.The spherical templates were derived from the spherical templates. The most important of this method was coat a H3BO3coating layer on the precursor particles, which could be reduced to h-BN protective film. This h-BN protective method could be successfully used to synthesize the spherical Sr2SisN8:Eu2+red phosphors, SrSi2O2N2:Eu2+green phosphor and hollow spherical Sr2SiO4:Eu2+green phosphor.In Chapter6we gave a brief summary of this paper. We pointed out the defects of this paper and predicted the direction in the investigation of phosphors in the future.