Optimization Of Traditional Phosphors With Rare Earth-Nitridsilicate Doping

Under the dual pressures of the energy crisis and energy-saving,reduction of lighting energy consumption has become a hot spot of the current research.With the development of the first blue light-emitting diode,due to their low power consumption and mercury-free environment-friendly features,white light emitting LEDs are considered to be the next generation of green light sources that can replace traditional lighting incandescent and fluorescent lamps.Therefore,the research of LED luminescent materials is of great significance to solve energy crisis.Rare earth ions doped materials are critically significant to lighting devices and can improve the performance of the equipment in practical application,so they are widely used in solid state lasers,solid state lightings,and LED devices.The researches on rare earth ions doped materials or rare earth ion host matrixes attact continuous attention in recent years.Therefore,it is important to develop novel fluorescent materials with high quantum efficiency and luminous efficiency and excellent color saturation,and to adopt new technologies to optimize the traditional phosphors.Some researches focus on the modification of traditional phosphors to meet the requirements of new applications.This paper is divided into four chapters.First chapter mainly introduces the background of phosphors first.Then the definition of light and the principle of light-emitting phosphor are described.Followed by a list of several ways to generate white light.Several kinds of phosphors for commercial applications have been introducted,with the focuse on the structures of LuAG phosphor and G-La2Si2O7 phosphor.Finally,the purpose and main research contents of this paper are given.In the second chapter,Si-N doped LuAG phosphors were prepared through a novel rare earth-nitridsilicate assisted solid-state reaction method.The fluorescence properties of the LuAG phosphor were optimized.XRD,SEM,excitation and emission spectroscopy and afterglow decay curve were used for charecterizing the phase,morphology and fluorescence properties of the phosphor.The traditional substitution of Al-O bonds by Si-N bonds used with low-reactive Si3N4 as the dopant material,which decreased the emission intensity due to the nonuniformity of the dopant performance.The strong covalent Ce-N bond and Si-N bond in CeSi3N5 increased the amount of Ce3+ ions coordinated with N3-ions in the host matrix,and N3' ions tended to enter the nearest neighbor coordination of light-emitting center,Si-N bonds were evenly distributed in the lattice,which resulted in a red shift of the emission spectrum of the phosphor.Si-N co-doped LuAG:Ce phosphor synthesized by CeSi3N5 incorporation had a wider emission spectrum and better luminescence properties.And the persistence phenomenon was observed.So this method is effective to improve the fluorescence properties of the aluminate fluorescent material and enhance the afterglow performance.The third chapter introduces the optimized synthesis of G-La2Si2O7:Eu2+ silicate phosphor.The G-La2Si2O7 is mostly doped with trivalent rare earth ions,such as Ce3+ions and Eu3+ ions,while few study has been done on Eu2+ ions doping.The broad excitation wavelength and adjustable emission of Eu2+ ions are suitable for the fabrication of white light emitting diode.So the Eu2Si5N8 raw material was prepared as the Eu source,then G-type La2Si2O7:Eu2+ phosphors were synthesized by high temperature solid state reaction method.The phosphors exhibited a blue light emission under the excitation of 302 nm ultraviolet light,matching with n-UV LED.Meanwhile,the incorporation of N in Eu2Si5N8 was beneficial for the enhancement of emission intensity and the adjustment of emission wavelength and emission color.In conclusion,the introduction of Eu2Si5N8 had a great significance for the synthesis of G-La2Si2O7:Ev2+ phosphor with the improved luminescence intensity.The fourth chapter is the summary and prospect of the full paper.