Synthesis and multicolor luminescence of Tb³⁺ and Sm³⁺ co-doped LiGd(MoO₄)₂ phosphor

Herein, Tb³⁺ and Sm³⁺ single doped and co-doped LiGd(MoO₄)₂ phosphors were prepared via a sol–gel method. X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM) fluorescence spectroscopy were utilized to investigate the structure, morphology and luminescent properties of the samples, respectively. XRD and FESEM analyses show that the samples are tetragonal phase crystals with an average size of 3 μm. In the photoluminescence excitation spectra, the MoO₄²⁻ group plays a dominant role in absorbing near ultraviolet light and transferring energy to Tb³⁺ and Sm³⁺. Under the excitation of 287 nm ultraviolet light, both the green emission of Tb³⁺ and the orange–red emission of Sm³⁺ could be observed from the emission spectra of LiGd(MoO₄)₂: 0.01 Tb³⁺, xSm³⁺ phosphors. Accordingly, LiGd(MoO₄)₂: 0.01 Tb³⁺, 0.01Sm³⁺ phosphor shows an emission color that can be modulated from yellow to red, and then to yellow–green light when excited by 287, 365, 377, 405, 417, 465, 483, and 488 nm, respectively. As a result, the tunable emission color of the phosphors can be provided by changing the doping concentration of Sm³⁺ and the excitation wavelength.