Exploring a new Sm3+-activated tungstate phosphor with thermally stable photoluminescence

In recent years, there is a great demand for the development of orange-red phosphors for temporary applications in the sides of lighting and display. This study investigated the photoluminescence properties of a new tungstate phosphor Li3Ba2Gd3-x(WO4)(8):xSm(3+) synthesized using traditional high-temperature solid-state reactions. In response to 405 nm light excitation, three main peaks appeared at 647, 610, and 592 nm. This represents the 4f -> 4f characteristic transition of Sm3+. Due to concentration quenching effect, x = 0.12 is the best concentration for Sm3+ ions doping, and further increasing Sm3+ will decrease emission intensity. Using experimental data, the critical energy transition distance at which concentration quenching occurs can be determined to be 10.8 angstrom, meaning primarily an interaction between dipoles. In the decay curves of Li3Ba2Gd3-x(WO4)(8):xSm(3+), the luminescent lifetimes decreased from 830 to 509 mu s as Sm3+ concentration increased. Color coordinates of Li3Ba2Gd2.88(WO4)(8):0.12Sm(3+) are (0.593, 0.406), which correspond to orange-red color. Moreover, the phosphor exhibited good thermal stability, retaining 65.2% of its intensity at 200 degrees C comparing with that at 25 degrees C. According to these results, Li3Ba2Gd2.88(WO4)(8):0.12Sm(3+) is a good orange-red phosphor for light-emitting diodes.