Preparation And Photpluminescence Properties Of Phosphate Phosphors For White-Light-Emitting Diodes

White light emitting diodes (WLEDs) with the advantages of low energy consumption, small volume, high efficiency, strong shock resistant, long life and no mercury pollution, are known as the new generation illuminate lamp. The main preparation methods of phosphor are high-temperature solid-state reaction, chemistry precipitation, sol-gel method, combustion synthesis, hydrothermal method, and so on. The rare earth materials serving as luminescent materials display irreplaceable advantages such as:high light-conversion efficiency, strong capacity of absorbing energy, excellent stability of physical and chemical properties, and so on. In this paper, new good performances phosphors were synthesized.In the third chapter, firstly, a new blue emitting phosphor Sr5Cl0.75F0.25(PO4)3: Eu2+ has been synthesized by high-temperature solid-state reaction. The crystal structure of the phosphor was characterized by X-ray powder diffraction (XRD); The microstructure of the phosphor was observed by field-emission scanning electron microscope (FE-SEM); The photoluminescence properties of this blue-emitting phosphor were investigated by excitation and emission spectra. The effect of Eu2+-doped concentration on emission of the phosphor was investigated and the concentration quenching mechanism was discussed in detail. Also, the temperature-dependence luminescence properties of Sr5Cl0.7sF0.25(PO4)3:Eu2+ were compared with the commercial blue phosphor BaMgAl10O17:Eu2+ (BAM). lastly, a bright blue LED was fabricated by combination of an n-UV InGaN chip and the phosphor.In the forth chapter, a new blue emitting phosphor BasCl(PO4)3:Eu2+ was synthesized by high-temperature solid-state reaction. The excitation spectrum is a broad and continuous band from 220 to 420 nm and the emission spectrum is broad but asymmetrical band peaked at 436 nm. Also, the component, structure, morphology, and concentration quenching properties of BasCl(PO4)3:Eu2+ were studied.In the fifth chapter, a new a new self-activated phosphor Bas(PO4)3OH and a blue phosphor were synthesized by high-temperature solid state reaction and their photoluminescence properties were studied. The Bas(PO4)3OH phosphor without Eu2+ shows a broad blue-green emission band peaked at about 500 nm with the CIE coordinates of (0.178,0.325). The emission peak of Bas(PO4)3OH:Eu2+shifts to about 435 nm and the CIE coordinates shift to (0.155,0.035). The CIE coordinates change slightly with Eu2+-doped concentration increasing, indicating the good color stability.In the sixth chapter, a new blue phosphor SrsF(PO4)3:Eu2+ was synthesized by high-temperature solid state reaction, and its properties were studied. The phosphor shows broad excitation and emission specture, which can be excited by a NUV LED chip. The emission spectrumn was peaked at 438 nm, which exhibited blue light, and the phosphor has great color stability. The best concentration is 1.0%, and the concentration quenching mechanism is quadrupole-quadrupole interaction.