Photoluminescence properties of novel K_2Mg_2(MoO_4)_3:Sm~(3+) orange-red emitting phosphors for white light emitting diodes

摘要

A series of novel K2Mg2(MoO4)(3):xSm(3+) (x = 0.005-0.05) orange-red emitting phosphors were synthesized by the solid-state method. The crystal structure and photoluminescence properties were investigated through the X-ray diffraction (XRD) and photoluminescence spectra. When excited by 406 nm, these phosphors exhibit intense orange-red emissions at 604 nm attributing to the (4)G(5/2) - H-6(7/2) transitions of Sm3+ ions. The optimal Sm3+ ions concentration was determined to be 2 mol%, and the dipole-dipole interaction is responsible for the mechanism of concentration quenching. The photoluminescence intensity of K2Mg2(MoO4)(3):0.02Sm(3+) at 423 K is 71.1% of that at 303 K. The fluorescence decay lifetimes of obtained phosphors were calculated to be in the range of 1.829 to 1.759 ms. Furthermore, the CIE chromaticity coordinates of as-synthesized phosphors are situated in the region of orange-red. All the results manifest that these Sm3+-activated K2Mg2(MoO4)(3) phosphors could be considered as potential orange-red candidates for white light emitting diodes (WLEDs).