Synthesis and luminescence enhancement of red-emitting Sr9Y(PO4)7:Eu3+ phosphor through Gd3+ co-doping for white light-emitting diodes

A series of Sr9Y(PO4)7:Eu3+ and Sr9Y(PO4)7:Eu3+, Gd3+ red-emitting phosphors were prepared via a high-temperature solid-state method, Gd3+ ion was co-doped in Sr9Y(PO4)7:Eu3+ as sensitizer to enhance the luminescence property. The X-ray diffraction results verify that the structure of the as-prepared samples is consistent with the standard Sr9Y(PO4)7 phase. All the Sr9Y(PO4)7:Eu3+ samples show both characteristic emission peaks at 594 nm and 614 nm under near-ultraviolet excitation of 394 nm. The co-doping of Gd3+ significantly improves the luminescence intensity of the Sr9Y(PO4)7:Eu3+ phosphors due to the crystal field environment effect and energy transfer of Gd3+→Eu3+ caused by the introduction of Gd3+, especially Sr9Y(PO4)7:0.11Eu3+, 0.05Gd3+, which emission intensity is higher than that of Sr9Y(PO4)7:0.11Eu3+ by 1.21 times. The color purity and lifetime of Sr9Y(PO4)7:0.11Eu3+, 0.05Gd3+ phosphor are 88.26% and 3.7615 ms, respectively. A w-LED device was packaged via coating the as-prepared phosphor on n-UV chip of 395 nm with commercial phosphors. These results exhibit that the Sr9Y(PO4)7:Eu3+, Gd3+ red-emitting phosphor can be used as a red component in the w-LEDs application.