Photoluminescence properties of single component double-color-emitting phosphor Ca5(PO4)3Br:Eu2+,Mn2+ for white LEDs

Novel color-tunable Ca-5(PO4)(3)Br:Eu2+,Mn2+ single component phosphors have been firstly synthesized through high-temperature solid-state reaction. X-ray diffraction (XRD), scanning electron microscopy (SEM), decay curves, and photoluminescence (PL) including temperature-dependent PL properties were used to characterize the as-prepared samples. Ca-5(PO4)(3)Br:Eu2+ phosphors can be efficiently excited in the range of 250-450 nm, and give intense blue emission centering at 461 nm. A tunable color from blue to white and then to red was generated when Mn2+ ions were co-doped into the Ca-5(PO4)(3)Br:Eu2+, which is based on the energy transfer from Eu2+ to Mn2+ ions. The energy transfer is demonstrated to be a dipole-quadrupole mechanism. The temperature dependent luminescence properties of Ca-5(PO4)(3)Br:Eu2+ and Ca-5(PO4)(3)Br:Eu2+,Mn2+ phosphors have been studied in detail. Furthermore, the fabricated white LED showed the chromaticity coordinate (0.314, 0.285), color rendering index of 83, and correlated color temperature of 6248 K. All phenomena demonstrate that Ca-5(PO4)(3)Br:Eu2+,Mn2+ is a very promising candidate for use as UV white light-emitting diode (WLED) phosphor.