Eu2+-Activated CaSrSiO4: a New Red-Emitting Oxide Phosphor for White-Light-Emitting Diodes

Ca 1- x Sr 1- x Eu 2 x SiO 4 (CaSrSiO 4 :Eu 2+ ) phosphors were prepared by a novel aqueous solution technique using propylene glycol-modified silane (PGMS), combined with a freeze-drying process. The precursors were heat-treated under a reducing atmosphere with BaCl 2 flux. X-ray diffraction indicated that the obtained phosphors exhibited an α'-CaSrSiO 4 structure. The wavelength at the phosphors' maximum emission was systematically shifted beyond 600 nm as the Eu 2+ concentration was increased. The corresponding excitation spectra were extended to the visible light region (400–500 nm) with increasing Eu 2+ concentration. These results implied that CaSrSiO 4 :Eu 2+ is a red-emitting phosphor excited by near-UV and blue-light-emitting diodes.