Enhanced luminescence intensity of CaSi2O2N2: Eu2+ phosphor by using flux in the preparation process and incorporating Gd3+ ions

作者：Huo, Jiansheng; Lu, Wei; Shao, Baiqi; Song, Yan; Feng, Yang; Zhao, Shuang; You, Hongpeng^*

来源：Journal of Luminescence, 2016, 180: 46-50.

DOI：10.1016/j.jlumin.2016.08.014

• Phosphor
• CaSi2O2N2:Eu2+
• Flux
• Gd3+ doped
• Luminescence

In this study, CaCl2, NH4Cl, and CaF2 were selected as the flux respectively to assist the preparation of the yellow emitting phosphor of CaSi2O2N2:Eu2+ by the solid-state reaction method. The influence of flux nature on the crystalline structure, morphology and photoluminescent behavior of the CaSi2O2N2:Eu2+ was extensively investigated. Results proved that adding flux can significantly enhance the crystallinity and the emission intensity of the resultant powders. Pure and well crystallized CaSi2O2N2:Eu2+ was formed by using CaCl2 flux at a relatively low temperature (1250 degrees C) and gave much enhanced yellow emission intensity than that in other samples (around 1400 degrees C). Further increase of the emission intensity was achieved by the Gd3+ doping. The experimental results showed that the doping of a certain amount of Gd3+ can expand the lattice and improve the absorption and emission intensity of CaSi2O2N2: Eu2+. When the Gd3+ content (x) increases up to 0.04 the luminescence intensity reaches maximum which is about 2 times as that of the phosphor without Gd3+ doping. A white light LED lamp using the optimal phosphor (Ca0.89Eu0.05Gd0.04Si2O2N2) had the color temperature of 5100 K with luminous efficiency of 41 Im W-1 and color rendering index of Ra=76, indicating that Ca0.89Gd0.04Si2O2N2:0.05Eu(2+) is a good candidate yellow emitting down-conversion phosphor for white LEDs application.