Red phosphors play a vital role in improving the photoluminescence properties of white LEDs (w-LEDs). In order to prepare high efficiency and stability red phosphor for commercial LED chips, a series of tetragonal scheelite structure Na1-xMxCaEu(WO4)3 (M = Li, K) red phosphors were synthesized by a solid state reaction method. The effect of Li + and K + doping on the crystal structure, photoluminescence properties and thermal quenching characteristics of NaCaEu(WO4)3 phosphor were investigated

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... ystematically. Rietveld refinement results show that the doping of Li + and K + does not change the tetragonal scheelite structure of the NaCaEu(WO4)3 host, but forms the solid solution, and results in the regular change in the lattice constant. The photoluminescence spectra show that under the excitation of near ultraviolet light at 395 nm, the phosphors exhibit a typical red emission, and its strongest emission peak is at 617 nm, corresponding to the 5 D0→ 7 F2 transition of Eu 3+ ion, which indicates that Eu 3+ is situated in non-central symmetric lattices in NaCaEu(WO4)3 host. It is more noteworthy that the doping of Li + and K + effectively improves the emission intensity