White-emission in single-phase Ba2Gd2Si4O13:Ce3+,Eu2+,Sm3+ phosphor for white-LEDs

To develop new white-light-emitting phosphor, a series of Ce3+-Eu2+-Sm3+ doped Ba2Gd2Si4O13 (BGS) phosphors were prepared by the solid-state reaction method, and their photoluminescence properties were studied. The Ce3+ and Eu2+ single-doped BGS show broad emission bands around in the region of 350-550 and 420-650 nm, respectively. By co-doping Ce3+-Eu2+ into BGS, the energy transfer (ET) from Ce3+ to Eu2+ is inefficient, which could be due to the competitive absorption between the two activator ions. The Sm3+-activated BGS exhibits an orangey-red emission in the region of 550-750 nm. To achieve white emission, the BGS:0.06Ce(2+),0.04-Eu2+,ySm(3+) (0 <= y <= 0.18) phosphors were designed, in which the ET from Ce3+/Eu2+ to Sm3+ was observed. The emission color can be tuned by controlling the Sm3+ concentration, and white emission was obtained in the BGS:0.06Ce(3+),0.04Eu(2+),0.06Sm(3+) sample. The investigation of thermal luminescence stability for the typical BGS:0.06Ce(3+),0.04Eu(2+),0.06Sm(3+) sample reveals that the emission intensities of both Eu2+ and Sm3+ demonstrate continuous decrease but the Ce3+ emission is enhanced gradually with increasing temperature. The corresponding reason has been discussed. (C) 2017 Elsevier B.V. All rights reserved.