Giant enhancement of photoluminescence in Mn4+-activated Ba2CaWO6 phosphors via heterovalent doping with rare-earth ions

Currently, Mn 4+ -activated phosphors have attracted extensive attention for their versatile applications in general lighting, display and plant cultivation. Owing to 3d 3 electronic configuration of Mn 4+ ion, modifying its local coordination environment emerges as a potent method to tailor its luminescence behavior. Herein, a heterovalent substitution strategy is reported to greatly enhance the photoluminescence (PL) of Ba 2 CaWO 6 :Mn 4+ . The effects of the substitution of rare-earth ions (Ln 3+  = Lu 3+ , Y 3+ , Gd 3+ , La 3+ ) for Ca 2+ ions on the PL properties of the phosphor are studied in detail. The PL spectral change of Mn 4+ induced by Ln 3+ substitution is clarified in terms of the local structure of [WO 6 ] octahedron and the valence state of Mn. By selection of Ln 3+ ions and optimization of Ln 3+ doping concentration, the emission intensity of Ba 2 Ca 0.85 Gd 0.15 WO 6 :0.25Mn 4+ phosphor reaches up to 46.3 times as that of Ba 2 CaWO 6 :0.25Mn 4+ . Besides, the Ba 2 Ca 0.85 Gd 0.15 WO 6 :0.25Mn 4+ phosphor exhibits an internal quantum yield of 56.9 % and a thermal stability of 72.6 %@423 K. Finally, Ba 2 Ca 0.85 Ln 0.15 WO 6 :Mn 4+ based phosphor conversion LED devices are demonstrated, which can be potentially employed for indoor plant lighting.