Achieving Efficient Red-Emitting Sr(2)Ca(1-delta)Ln(delta)WO(6):Mn4+ (Ln = La, Gd, Y, Lu, delta = 0.10) Phosphors with Extraordinary Luminescence Thermal Stability for Potential UV-LEDs Application via Facile Ion Substitution in Luminescence-Ignorable Sr2

Abstract

In this work, we adopt a facile rare earth ions Ln(3+) (Ln = La, Gd, Y, Lu) substitution strategy to achieve the efficient red luminescence Sr(2)Ca(1-delta)Ln(delta)WO(6):Mn4+ (delta = 0.10), which extremely improves the luminescence properties of luminescence-ignorable Sr2CaWO6:Mn4+. It is demonstrated that the substitution of Ln(3+) for Ca2+ can stabilize the Mn in tetravalent state, which would like to occupy W6+ site and generate the luminescence. It is also found that the emission profile of original Sr2CaWO6:Mn4+ changes manifestly after different Ln(3+) ions substitution, which is mainly attributed to the synergistic effect of lattice distortion, Mn4+ transition E-2(g) -> (4)A(2g) and lattice vibration. Most fascinatingly, the Sr(2)Ca(0.9)Ln(0.1)WO(6):0.005Mn(4+) (SC(0.9)Ln(0.1)WO:0.005Mn(4+), Ln = La, Gd) show extraordinary luminescence thermal stability, whose integrated emission intensity still maintains about 95% (Gd, 96.8%; La, 94.8%) at 478 K of its original value at room temperature (298 K), much better than those in most reported M4+-activated oxide phosphors so far. It is confirmed that the traps may play an important role for this phenomenon. Best of all, this work gives us a facile strategy to achieve efficient Mn4+-activated red-emitting materials with extraordinary luminescence thermal stabilities derived from luminescence-ignorable ones.