Regulation of color tunability of Dy3+/Eu3+-based double molybdate phosphors with high thermal stability

In this paper, a series of NaLu(MoO4)2:Dy3+ green phosphors and NaLu(MoO4)2:Dy3+,Eu3+ multi-color tunable phosphors were prepared by an EDTA-2Na assisted hydrothermal method. The emission of Dy3+ ions at two characteristic peaks at 469 nm and 573 nm was observed for the NaLu(MoO4)2:xDy3+ phosphor excited at 355 nm. Through calculation and data fitting, the concentration quenching of Dy3+ ions in the NaLu(MoO4)2 lattice is dominant due to the dipole-dipole interaction. The variable temperature emission spectra show that the luminescence intensity of the NaLu(MoO4)2:0.01Dy3+ phosphor at 423 K decreases to 59% of that at 298 K, while the NaLu(MoO4)2:0.01Dy3+,0.07Eu3+ phosphor at 423 K remains at 97% compared to that at room temperature, indicating that the thermal stability of the phosphor is greatly improved by the introduction of Eu3+ ions. In addition, by adjusting the ratio of Dy3+ to Eu3+ ions in the host, the luminescence color gradually changes from green to yellow and finally to orange-red, providing insights into color tuning in the visible range toward various applications. In summary, the Dy3+ and Eu3+ co-doped NaLu(MoO4)2 phosphor is a phosphor with good optical properties and excellent thermal stability, which can achieve color tunability and has potential application prospects in the fields of color display and lighting.