An intense red-emitting phosphor Sr3Lu(PO4)3:Eu3+ for near ultraviolet light emitting diodes application

A series of Sr3Lu(PO4)3:Eu3+ phosphors were successfully prepared via the solid-state method, and their luminescence properties were investigated. The excitation and emission spectra show that this phosphor can be effectively excited by near ultraviolet (NUV) light, and produces strong and prevailing red emissions at 612 nm belonging to the 5D0→7F2 electric dipole transition. Eu3+ ion was heavy doped in Sr3Lu(PO4)3 host and the optimal concentration of Eu3+ was found as 0.8. The critical transfer distance of Eu3+ was determined to be 8.5 Å. The concentration quenching was demonstrated to be caused by the energy transfer among the nearest-neighbor ions in the Sr3Lu(PO4)3:Eu3+ phosphor. Under excitation of 394 nm, the integral emission intensity of Sr3Lu0.2(PO4)3:0.8Eu3+ is about 6 times that of Y2O3:Eu3+. The CIE color coordinates of Sr3Lu0.2(PO4)3:0.8Eu3+ was (0.636, 0.354) located in red region. In addition, good thermal stability was also identified in Sr3Lu0.2(PO4)3:0.8Eu3+ and its emission intensity was reduced to 88% of its initial value at 100 °C and 70% at 200 °C. The current research suggests that Sr3Lu(PO4)3:Eu3+ could be a promising red phosphor for white LEDs and display devices.