Preparation And Characterizatic Of Sr₂Mgsi₂O₇:Eu²⁺Blue Phosphors For White LEDs

White light emitting diodes (WLEDs) are considered to be the fourth generation lighting systems because of advantages such as small size, energy conservation, long life, environmental protection and reliability compared to conventional light bulbs. Today, the white LED market is dominated by Phosphor-converted LEDs (PcLEDs). However, the commercialized white PcLEDs comprising a blue emitting InGaN semieonductor coated with yellow phosphor (YAG:Ce) have some defects, such as worsecolor restoration, low color rendering index and so on. For this reason, it is also a potential for white LEDs that near-UV LEDs are utilized to replace the traditional white PcLEDs comprising a blue emitting InGaN dies. The current commercially applicable blue phsphor is BaMgAl10O7:Eu2+. However, BaMgAl10O7:Eu2+phosphor has some disadvantage in terms of low thermal stability and serious degradation and color drifting and so on. Therefore, it is important to study the high efficient blue phosphors matching near UV LED to enhance luminous efficiency of white LEDs.In this paper, the phosphors Sr2MgSi207:Eu2+, R(R=Gd3+, Mn2+, Zn2+, Zr4+) are synthesized with a small amount of NaF flux using high-temperature solid state reaction method, and the phosphors Sr2MgSi2O7:Eu2+, Bi3+are synthesized using sol-gel method to analyze their emission and structural and luminescent properties from the characterisation of their XRD, DTA-TG, and PL spectra.In this paper, it was found that doping a small amount of NaF flux could improve crystallinity, and luminescent intensity of Sr2MgSi2O7:Eu2+phosphor. The excitation spectra of Sr2MgSi2O7:0.04Eu2+sample exhibit a wide band from270nm to430nm with the peak at358nm. Excited at358nm, the phosphor exhibit a wide and strong blue emission band centering at470nm, which is due to the4f65d1â†'4f7electric-dipole transition of Eu2+.The luminescent intensity of the samples with uniform center particle size (D50) is better than that with particle sizes distribution. Doping a small amount of Gd3+, Mn2+, Zn2+, Zr4+ions in the Sr2MgSi2O7:Eu2+phosphor does not change the phases structure, but can impove the luminescent intensity. When doping Gd3+at0.01mol, luminescent intensity of phosphor increases up to3.04times compared with phosphor without doping Gd3+; When doping Mn2+at0.03mol, luminescent intensity of phosphor increase up to3.39times that of phosphor without doping Mn2+; When doping Zn2+at0.05mol, luminescent intensity of phosphor increase up to2.58times that of phosphor without doping Zn2+; When doping Zr4+at0.04mol, luminescent intensity of phosphor increase up to5.16times that of phosphor without doping Zr4+.In the study of Sr2MgSi2O7:Eu2+, Bi3+phosphor, it was found that emission spectra of Sr2MgSi2O7:Bi3+powder phosphors with λex=286nm (3P1â†'1S0) and Sr2MgSi207:Eu2+,xBi3+(x=0,0.02,0.04,0.06,0.08) phosphors with λex=358nm (4f65d1â†'4f7) have been analyzed. Based on the emission performance of Sr2MgSi2O7:Eu2+,xBi3+, the Bi3+concentration has been optimized to be at0.04mol, and the luminescent intensity of the phosphor increases up to1.9times that of phosphors without doping Bi3+,due to the sensitizing of Bi3+to Eu2+.