Synthesis and photoluminescence of the blue phosphor Sr3MgSi2O8:Eu2+ optimized with the Taguchi method for application in near ultraviolet excitable white light-emitting diodes

In order to develop highly efficient blue phosphor for near ultraviolet excitable white light-emitting diodes, a series of M3MgSi2O8:Eu2+ (M=Sr, Ba, Ca) phosphors were synthesized with conventional solid-state reaction method. First, the concentrations of Eu2+ and the firing temperatures were optimized. Meanwhile, the critical distance for energy transfer between different activators of Eu2+ is evaluated and the mechanism of concentration quenching is explored. Next, the contents of Ba2+ and Ca2+ were tailored for regulating luminescence efficiency and chromaticity. Moreover, five fluxes (NH4Cl, AlF3, NaCl, KBr, and H3BO3) each with different fusing and boiling points were optimized using the Taguchi method. Based on the optimizations, a blue phosphor with luminescence intensity of about 10% higher than the commercially available one was finally obtained. The crystallinity and morphology, characterized by using an X-ray diffractometer and a Field Emission Scanning Electron Microscope respectively, provide reasonable evidences to explain the enhanced luminescence. The photoluminescence properties including excitation and emission were investigated using a fluorescence spectrophotometer.