Preparation Eu-doped ca-α-SiAlON phosphor by heterogeneous precipitation: An orange–yellow phosphor for white light-emitting diodes

Abstract

In this research, Ca-α-SiAlON phosphors with compositions of Ca1−xEuxSi9Al3ON15 (x=2.5%, 5.0%, 7.5%, 10.0% and 15.0%) were synthesized by heterogeneous precipitation processing. The solid state reaction and nitridation reaction were completed at 1400–1500°C for 12h in a flow of N2–H2 (H2, 5vol%). The phase of α-SiAlON was prepared at 1450°C for 12h. The phosphors showed strong and broad absorption in the range of 230–530nm and a broad orange–yellow emission band ranging from 500 to 700nm for peaking at 582–600nm which were corresponding to the phosphor prepared by the conventional solid state reaction. The results indicate a concentration quenching effect at x≥7.5% and a systematic red-shift in emission wavelength as the heat-treatment temperature or the Eu2+ concentration increases. The quantum efficiency of the sample heat-treated at 1600°C for 12h, reached 70.56% (internal) and 45.7% (external) with the 450nm excitation. The corresponding CCT (Correlated color temperature) range of white LED lamps consisting of a blue LED chip and the Ca-α-SiAlON phosphor can be ranging from 2000 to 2700K.