Photoluminescence Characteristics of Energy Transfer Between Eu3+and Bi3+in LiEu1−xBix (WO4)0.5(MoO4)1.5

A series of novel red phosphors LiEu_{1− x} Bi _x (WO₄)_0.5(MoO₄)_1.5 ( x =0, 0.05, 0.10, 0.15, 0.20, 0.30, 0.40, and 0.50) were synthesized by the conventional solid-state reaction method. The spectrum and the crystal structure of the phosphors were characterized by Fluorescence spectrophotometry and X-ray diffraction, respectively. The photoluminescent results show that all samples can be excited efficiently by UV (396 nm) and blue (467 nm) light and that they emit red light at 615 nm with line spectra, which are coupled well with the characteristic emissions from UVLED and blue light-emitting diode (LED), respectively. There is an efficient energy transfer from Bi³⁺ to Eu³⁺ ions, leading to the emission intensity of Eu³⁺ being enhanced by 1.5 times, and even more when Bi³⁺ ions are introduced into LiEu (WO₄)_0.5(MoO₄)_1.5. The introduction of Bi³⁺ ions broadened the excitation band of the phosphor, and the optimum doping concentration is found to be 10 mol% of Bi³⁺.