Abstract: A series of orange-red phosphors, Na₅Y_1-x(MoO₄)_4-y(WO₄)_y∶xSm³⁺(x=0~0.10, y=0~4), were synthesized by high temperature solid state method. The properties of the phosphor samples were studied by means of X-ray diffraction, transmission electron microscope, normal/variable temperature fluorescence emission spectrum, fluorescence excitation spectrum, fluorescence dynamic attenuation curve, CIE chromaticity coordinates and so on. XRD results show that the phase of the synthesized samples is consistent with the standard of Na₅Y(MoO₄)₄, and the phase structure of the materials is unchanged by introducing Sm³⁺ or (WO₄)^2-. Under the excitation of 406 nm, Na₅Y_0.92(MoO₄)₃(WO₄):0.08Sm³⁺ has the highest emission intensity. With increasing doping concentration of Sm³⁺, the concentration quenching phenomenon appears, and the main reason for the concentration quenching is attributed to the electric dipole-electric dipole interaction. The study found that the doping of rare earth ions in the Na₅Y(MoO₄)₄ matrix would cause electronegativity changes and lattice distortion. The introduction of (WO₄)^2- anionic groups into Na₅Y_1-x(MoO₄)₄∶xSm³⁺ can make up for the defects caused by the doping of Sm³⁺ and further improve the luminescence performance of Na₅Y_1-x(MoO₄)₄∶xSm³⁺ phosphors. In the range from 300 K to 440 K, the samples have excellent thermal stability, and the fluorescence intensity is more than 96% higher than that at room temperature. The CIE chromaticity coordinates are located in the orange-red region. These results indicate that the Na₅Y_1-x(MoO₄)_4-y(WO₄)_y∶xSm³⁺ phosphor has potential value in WLED applications.

Key words: Na₅Y(MoO₄)₄, phosphor, Sm³⁺ doping, high temperature solid state method, fluorescence intensity, thermal stability, WLED