Study On The Synthesis Of Green、Orange-red Phosphors Used For White LED And The Luminescence Properties

White LEDs have drawn much attention in recent years for their excellent characteristics, such as low energy consumption, high efficiency, reliability,long lifetime, etc. Up to now, commercial white LEDs are generally realized through combining blue InGaN chip and a yellow-emitting phosphor YAG:Ce3+ phosphor. Although the luminescence efficacy and the color rendering index is enough for the use of general illumination, it is not suitable for application in backlight of the liquid crystal display and medical lighting because of the deficiency of red emission, In order to realize the output of warm white lights, one alternative way is near-ultraviolet (NUV) (350-410 nm) chip combined with tricolor (red/green/blue) phosphors. In this study, LU3Al5O12:Ce3+, (Sr0.883Ba0.1Lu0.017)3(Si0.95Al0.05)O5:Eu2+ and CaTiO3:Eu3+ phosphors were synthesized by a solid-state method.1. Lu3Al5O12:Ce3+ green phosphors were synthesized by synthesized conventional solid-state reaction. Crystal structure and luminescent properties of the phosphors were investigated by adding various fluxes (BaF2, HBO3, NH4Cl and NaF), the content of BaF2 flux were optimized for maximum luminescence intensity, as well as, The luminescent properties of Lu3Al5O12 doped with different concentration of Ce3+ are investigated. When the concentration of Ce3+ is 0.05 mol, the phosphor has maximum emission intensity at around 513 nm. The obtained phosphors had a broad strong absorption around wavelength 354 nm and 450 nm, which well match the emission of n-UV or blue InGaN chips.2. Orange-red emitting (Sr0.883-xBa0.1Lu0.017Eux)3(Sio.95Al0.05)O5 phosphors were synthesized by conventional solid-state reaction. The effect of NH4F flux on structural and luminescent properties of phosphors was investigated. Results suggested that the optimal content of NH4F flux was 3 wt.% and the optimal doping concentration of Eu2+was when x=0.023mol.Combining a InGaN blue 460 nm chip and a white-emitting (Sr0.86Ba0.1Lu0.017Eu0.023)3(Si0.95Al0.05)O5 phosphor produced a white-light LED, demonstrating CIE chromaticity coordinates of (0.314,0.329) and a color temperature of 5595 K. All results show that this phosphor is a promising candidate as orange-red emitting phosphor for white light emitting diode (w-LED) application.3. Red phosphors of Zn-doping CaTiO3:Eu3+ has been synthesized by a solid-state method. The morphology of the obtained phosphor samples were observed by SEM, and the impact of Zn and Eu concentration on photoluminescence properties was studied. The result showed that Zn-doping phosphor was efficiently excited by near-ultraviolet (NUV) light at wavelength around 398 nm and emitted intense red light with a broad peak around 616 nm corresponding to the 5D0�'7F2transition of Eu3+, and the intensity of this phosphor is three times stronger than that of without Zn-doping CaTiO3:Eu3+ phosphors. Furthermore, this phosphor has very good thermal stability, high color purity and low sintered temperature.