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

Abstract

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.