Synthesis and photoluminescence properties of Eu2+-activated Sr9In1-yLuy(PO4)7 phosphors

In this work, two series of phosphors of Sr9-xIn(PO4)(7):xEu(2+) and Sr8.97In1-yLuy(PO4)(7):0.03Eu(2+) with beta-Ca-3(PO4)(2)-type structure are prepared via a high temperature solid-state reaction. The XRD, photoluminescence, photoluminescence excitation spectra and decay times are investigated in detail. Upon excitation at 365 nm, the Sr9-xIn(PO4)(7):xEu(2+) phosphors show a obvious band centered at 410 nm and a little hump peaked at 630 nm ascribed to the 4f(6)5d(1)-4f(7) transitions of Eu2+ in different crystallographic sites. The excitation spectra show a broad band in the 250-500 nm, which is well-matched with the NUV LED chip. For the Sr8.97In1-yLuy(PO4)(7):0.03Eu(2+) phosphors, the another emission band centered at 520 nm emerged with the substitution of Lu3+ for In3+ on the basis of Sr9In(PO4)(7):Eu2+ phosphor under the 365 nm excitation, which indicates that the presence of different Eu2+ luminescence centers. And emitting-color can be tuned from bluish-violet to white and yellow-green by varying the ratio of Lu3+ and In3+. Our results indicate these phosphors can be as an attractive candidate for the application of white LEDs by ions substitution to obtain white light and tunable luminescent.