Abstract
Ce 3+ doped La 4Ca(SiO 4) 3O phosphors with silicate oxyapatite structure were synthesized by the sol-gel process. The X-ray diffraction (XRD) patterns showed that a pure phase was formed when sintering temperature was higher than 1300°C. The optical properties of La 4Ca(SiO 4) 3O:Ce 3+ phosphors with varying sintering temperature and concentration were investigated by examining their excitation and emission spectroscopy. The phosphors exhibited a broad emission band centered at 550nm which could be attributed to the 5d-4f transition of Ce 3+ and a stronger excitation peak around 467nm as well as several shoulder bands, nicely matching with the widely applied blue LED chips. Higher emission intensity was observed when firing temperature above 1300°C, due to increasing crystallinity of the powders. When Ce 3+ concentration was equal to 5 at%, the sample exhibited the optimum excitation and emission efficiency. The results indicate that La 4Ca(SiO 4) 3O:Ce 3+ is a promising candidate in the application of blue chip excited white light emitting diodes (LEDs).
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