Efficient energy transfer, excellent thermal stability and near-ultraviolet excited WLED application of NaLu(MoO4)2:Sm3+,Eu3+ red phosphors

A series of NaLu(MoO 4 ) 2 (NLMO): Sm 3+ phosphors and Sm 3+ , Eu 3+ co-doped NLMO phosphors were synthesized by high-temperature solid-state method. Their crystal structures and luminescent properties were systematically characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), fluorescence spectroscopy, fluorescence lifetime, and temperature-dependent emission spectroscopy. XRD results confirm that Sm 3+ and Eu 3+ are successfully doped through isovalent substitution of Lu 3+ sites without destroying the pure NLMO phase structure. Under 405 nm near-ultraviolet excitation, the optimal doping concentration of Sm 3+ is 0.04 mol, and the concentration quenching mechanism is dipole-dipole interaction. Efficient Sm 3+ →Eu 3+ energy transfer is observed in the co-doped system, which is further verified by the fluorescence lifetime measurement of Sm 3+ . The maximum energy transfer efficiency reaches 81%, with the dominant mechanism identified as dipole-dipole interaction. The NLMO:0.04Sm 3+ ,0.07Eu 3+ phosphor exhibits excellent thermal stability, retaining 81% of its emission intensity at 303 K when heated to 383 K, and the thermal quenching activation energy is as high as 0.331 eV. CIE chromaticity coordinates show that the emission color of the phosphor gradually shifts from orange-red to red with increasing Eu 3+ doping concentration, and the correlated color temperature is observed between 1753 K and 2339 K. These results demonstrate that the NLMO:Sm 3+ , Eu 3+ phosphor integrates high energy transfer efficiency, outstanding thermal stability, and precise color tunability, making it an ideal red component for near-ultraviolet excited white light-emitting diodes with significant practical application value.