Photoluminescence Properties and Energy Transfers in the Novel LiYMgWO₆: Dy³⁺, Tm³⁺

A series of Dy³⁺/Tm³⁺ single doped and co-doped double perovskite-structure compound LiYMgWO₆ (LYMW) are prepared by a solid-state route. The structure and photoluminescence properties have been unraveled by combining experiments and first-principles calculations. The crystal structure was determined to be a monoclinic structure with space groups P2₁. Under the ultraviolet (UV) excitation, Dy³⁺ and Tm³⁺ single doped LYMW samples emit yellowish-white and blue light, respectively. For Dy³⁺ and Tm³⁺ co-doped LYMW, the emission can be tuned from blue to white light and eventually to yellow through energy transfers by varying the Dy³⁺ and Tm³⁺ concentrations. The sample with 3%Dy³⁺ and 3%Tm³⁺ has chromaticity coordinates (0.3405, 0.3378), which are nearest to the ideal white light (0.33,0.33). The energy transfer mechanism is verified to be the quadrupole-quadrupole interaction. The temperature-dependent photoluminescence (PL) spectra show that LYMW: Dy³⁺, Tm³⁺ exhibits good thermal stability.