Color-regulation and luminescence properties of NaYMgWO₆:Tm³⁺, Dy³⁺, Sm³⁺ phosphor with high thermal stability

Novel double perovskite-structured phosphors, NaYMgWO₆: Tm3⁺, Dy3⁺, Sm3⁺, were successfully synthesized via the solid-state reaction method. The material's band gap was confirmed through material simulations using Material Studio and the Tauc plot method. The phase structure was thoroughly examined using XRD and Rietveld refinement methods, while the microstructure was observed via SEM. The optical performance was characterized through PL & PLE spectra, CIE, and fluorescence lifetime analysis. NYMWO₆, when individually doped with 1 mol% Tm³⁺, 5 mol% Dy³⁺, and 7 mol% Sm³⁺, exhibited the highest intensity of blue, yellow, and red light, respectively. By co-doping 1 mol% Tm³⁺ and y mol% Dy³⁺ (y = 1, 3, 5, 7, 9, 11, 13), a tunable cold-white light phosphor was successfully fabricated, with CIE coordinates ranging from (0.235, 0.166), CCT = 6949 K, to (0.364, 0.357), CCT = 4358 K. The highest luminescence intensity was observed at y = 9 mol%. Furthermore, by co-doping 1 mol% Tm³⁺, y mol% Dy³⁺, and 7 mol% Sm³⁺ (y = 1, 3, 5, 7), the emission range shifted entirely from the cold-white region to a tunable warm-white region (CCT = 3000–––4000 K). The highest luminescence intensity was observed at y = 5 mol%. Additionally, the material exhibited excellent thermal stability at y = 1 mol%, where the color temperature reached 3099 K, showing warm-white emission and retaining 84.7 % of its initial intensity at 151.85 °C.