Ca9Lu(PO4)7:Eu2+,Mn2+: A Potential Single-Phased White-Light-Emitting Phosphor Suitable for White-Light-Emitting Diodes

A novel white-light-emitting phosphor Ca9Lu(PO4)7:Eu2+,Mn2+ has been prepared by solid-state reaction. The photoluminescence properties indicate that there is an efficient energy transfer from the Eu2+ to Mn2+ ions via a dipole-quadrupole reaction. The obtained phosphor exhibits a strong excitation band between 250 and 430 nm, matching well with the dominant emission band of a UV light-emitting-diode (LED) chip. Upon excitation of UV light, white light is realized by combining a broad blue-green emission band at 480 nm and a red emission band at 645 nm attributed to the Eu2+ and Mn2+ ions. The energy-transfer efficiency and critical distance were also calculated. Furthermore, the phosphors can generate lights from blue-green through white and eventually to red by properly tuning the relative ratio of the Eu2+ to Mn2+ ions through the principle of energy transfer. Preliminary studies showed that the phosphor might be promising as a single-phased white-light-emitting phosphor for a UV white-light LED.