Study On Synthesis And Performance Of YAG Yellow Phosphors For White LED

Because of petrifaction resources'lack, many countries have attached importance to worldwide energy sources crisis and bring lighting thrift techniques, especially white LED into national development stratagem. Compared with conventional lighting sources, white LED has many merits in energy saving, compact optics designs, cold source, startup at low volt or electrical current, long life-span, rapid brightness and color changes, aseismatic, recyclable, unpolluted and so on, there's obvious benefits to economic and environment. Whereas, if white LED illuminance would realize finally, there will be much works in playing down cost and increasing LED'color reveal index, luminescence efficiency, luminous flux and life-span. This paper intends to prepare YAG:Ce yellow phosphor by high-temperature solid state reaction, investigate several technique parameters which affect phosphor's physical and chemical properties, and study the effects of different ions doping on fluorescence emitting spectrum, further more, gained white LED lamps with good color reveal propertiy, lighting extraction, luminescence efficiency. The following is included:1) The present status and prospect of white LED illumination industry is reviewed firstly. Then it analysises the light emitting principle, realization methods and key materials of white LED, and puts the emphasis on the preparation techniques of the phosphors for white LED.2) The YAG yellow phosphor is synthesized by high-temperature solid state reaction under reducing atmosphere, and the chemical and physical properties are characterized with molecule fluorometry, X-ray diffracting, laser granularity analysis and OM instrument. To analysis the influence of sintering temperature, solid solution additives, sintering time and reaction atmosphere on phosphor's chemical and physical properties. The results show that, when sintering temperature is 1500℃, there will form pure YAG crystal phase, solid solution additives can reduce the sintering temperature to 1300℃, with carbon as reduce atmosphere and extending the sintering time will be propitious to synthesizing of phosphor.3) The effects of ion doping to light emitting spectrum of phosphors is studied, and the results indicate that when only Ce ion doped, the light emitting intensity of phosphor will firstly increase, then reduce with the increasing of doping concentration. When Cd or Tb doped with Ce, the light emitting spectrum of phosphor will take Einstein shift.