Synthesis and photoluminescence properties of Eu 2+ activated CaO ceramic powders for near-ultraviolet chip based white light emitting diodes

Abstract In this paper, we synthesized series of Eu 2+ activated CaO ceramic powders by conventional solid state reaction. Using NH 4 Cl as a reducing additives, the Eu 3+ has been successfully reduced to Eu 2+ . An intense blue emission peaked at 460 nm from Eu 2+ was observed. The luminescent intensity of the doping-optimized CaO:Eu 2+ sample can be as high as 106% of commercial BAM blue phosphor under 400 nm near-ultraviolet (NUV) excitation. The effect of Eu 2+ and NH 4 Cl contents on photoluminescence properties and crystal phase formation have been investigated, respectively. The thermal stable property which is an important performance for LED application has also been measured. The emission intensity at 120 °C can maintain 94% of that at room temperature. Our results suggest that CaO: Eu 2+ ceramic powder could be used as a promising blue emitting phosphor for NUV chip based white LEDs.