Effects of flux on crystal structure and luminescent properties of nitroxides phosphors

Abstract

Yellow-green-emitting SrSi2O2N2:Eu2+ phosphors were synthesized with Sr2SiO4:Eu2+ as precursor. The effects of flux and the concentration of Eu2+ on the crystal structure and luminescent properties of the phosphors were investigated. Results suggested that the optimal content of flux Na2CO3 was 1 wt% and the optimal doping concentration of Eu2+ was 0.05 mol. The emission spectra showed the most intense peaks located at 535 nm which corresponded to the 4f65d→4f7 transition of Eu2+. The excitation spectra showed that these phosphors could be effectively excited by near-ultraviolet and blue light, whichwas consistent with the widely applied output wavelengths of near-ultraviolet and blue-white light-emitting diode (LED) chips. When the influence of flux on the luminescent properties of SrSi2O2N2:Eu2+ phosphor was analyzed, the X-ray diffraction (XRD) patterns indicated that the flux could help the crystallization of the phosphors. No other phases except the triclinic structure of SrSi2O2N2 were formed. The thermal stability and the emission intensity of synthesized SrSi2O2N2:Eu2+ phosphor were examined and compared with commercial YAG yellow phosphors. All results indicate that the yellow-green-emitting phosphor is a suitable candidate for the fabrication of white LEDs.