Photoluminescence Properties of (Ba1-(x+y)SrxEuy)2Si6O12N2 Phosphors for White LED Applications

Abstract

(Ba1-(x+y)SrxEuy)2Si6O12N2 oxynitride phosphors were successfully synthesized by the solid-state reaction method at 1200°C under a H2(5%) + N2(95%) atmosphere. The Sr2+ content (x) was varied in the range 0-0.6 and the Eu2+ content varied in the range 0.05-0.25, with the Si/(Ba+Sr+Eu) ratio fixed at 3. Results showed that the emission characteristics of (Ba1-(x+y)SrxEuy)2Si6O12N2 phosphors under UV or blue-light excitation was strongly dependent on the chemical composition. The phosphor (Ba0.95Eu0.05) Si6O12N2 showed an intense green emission peak at 520 nm, whilst the phosphor (Ba0.45Sr0.5Eu0.05)Si6O12N2 had a weaker emission maximum at 548 nm. Ba2+ substitution with Sr2+ decreased the lattice volume of the (Ba1-(x+y)SrxEuy)2Si6O12N2 phosphors and was responsible for the red-shift in the emission peak. Optimization of the Eu2+ concentration at a fixed Sr2+ content of 0.2 identified the phosphor (Ba0.65Sr0.2Eu0.15)2Si6O12N2 as a potential alternative to YAG:Ce yellow phosphors for white LED applications.