Synthesis and luminescent properties of a novel red emitting La₂Mo₃O₁₂: Li⁺, Eu³⁺ phosphor

La₂Mo₃O₁₂: Eu³⁺ (5 mol%) red phosphors co-doped with different concentrations of Li⁺ ions have been synthesized by a citric acid based sol–gel method. X-ray powder diffraction, field emission scanning electron microscope, photoluminescence (PL) spectra and luminescence decay kinetics were used to characterize the synthesized samples. The results show that the excitation spectra of La₂Mo₃O₁₂: Li⁺, Eu³⁺ phosphors consist of a broad and strong absorption band in the ultraviolet (UV) and near ultraviolet (NUV) regions, which can be efficiently excited by the NUV light. The emission spectra of the phosphors exhibit characteristic luminescence ⁵D₀→⁷F_J (J = 1, 2, 3, 4) of the Eu³⁺ ions with a dominant electronic transition located at 615 nm (⁵D₀→⁷F₂). Incorporation of Li⁺ ions in La₂Mo₃O₁₂: Eu³⁺ lattice can induce a remarkable improvement of their PL intensity and the optimal concentration of Li⁺ is 15 mol%. Furthermore, the estimated chromaticity coordinate about (0.65, 0.34) is very close to the ideal red light (0.670, 0.330). These results indicate that the Li⁺ doped La₂Mo₃O₁₂: Eu³⁺ phosphors can serve as NUV excited red phosphors for white light emitting diodes.