Effect of Li+ and Er3+ co-doping on the luminescence properties of Ba2SiO4:Eu

A series of Ba1.99-x/2-2ySiO4:Eu-0.01(2+), Li-x+y(+), Er-y(3+) green phosphors were synthesized by one-step calcination process with precursor prepared by chemical precipitation. X-ray diffraction (XRD) and fluorescence spectrophotometry were employed to characterize the crystal structure and luminescent properties, respectively. The results show that co-doping of Eu2+, Li+ or Er3+ do not change the crystal structure. The excitation band of green phosphors Ba1.99-x/2-2ySiO4:Eu-0.01(2+), Li-x+y(+), Er-y(3+) extends from 270 to 440 nm, with peaks appearing around 288 and 360 nm, thus the phosphors can be excited effectively by InGaN chip which produces ultraviolet light in the range of 350-410 nm. The emission spectrum excited by 360 nm shows a characteristic wide band with a peak at about 500 nm, which can be attributed to the typical 4f(6)5d(1) -> 4f(7) transition emission of Eu2+. The emission spectrum intensity of Ba1.99-x/2SiO4:Eu-0.01(2+), Li-x(+) first increases with increasing Li+ doping concentration, and then decreases. The strongest emission intensity occars when Li+ doping concentration is 0.1. Two additional peaks appear in the emission spectrum of Ba1.99-x/2-2ySiO4:Eu-0.01(2+), Li-x+y(+), Er-y(3+) green phosphors around 488 nm and 530 nm separately when the phosphors are co-doped with Li+ and Er3+ from 0 to 0.012, which are attributed to the 4F(7/2) -> 4I(15/2) and H-2(11/2) -> 4I(15/2) translation emission of Er3+, the energy transfer effect from Eu2+ to Er3+ is also analyzed.