Sol-gel synthesis of yellow-emitting La4Ca(SiO4)3O:Ce3+ phosphors for white-light emitting diodes

Abstract: Ce3+ doped La4Ca(SiO4)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 La4Ca(SiO4)3O:Ce3+ 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 Ce3+ 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 Ce3+ concentration was equal to 5 at%, the sample exhibited the optimum excitation and emission efficiency. The results indicate that La4Ca(SiO4)3O:Ce3+ is a promising candidate in the application of blue chip excited white light emitting diodes (LEDs). [Copyright &y& Elsevier]