Photoluminescence enhancement of novel K(Y,Lu)CaWO6: Eu3+ red phosphor prepared by controllable citrate-EDTA complexing method

Novel double-perovskite K(Y_0.95-xLu_xEu_0.05)CaWO₆ red phosphors were successfully prepared by the controllable citrate-EDTA complexing method. XRD with structure refinement, FTIR, Raman and photoluminescence spectra were combined to systematically investigate the structure parameters and luminescence properties of prepared phosphors. The substitution of Lu³⁺ with smaller ionic radius resulted in the lower symmetry even with the same space group of C2/m, which was also directly observed from the red shift and splitting of Raman T_2?g(1) mode. The concentration higher than x?=?0.6 made the intensity alteration in the excitation spectra from charge transfer band to 4f?4f of Eu³⁺. The obvious enhancements of red emission at 615?nm were obtained under both blue and ultraviolet lights, respectively, and reached almost the same intensity at x?=?0.6. Meanwhile, the more standard red light could be found by the gradual shifts of CIE chromaticity coordinates and bigger ratio of red/orange emission. The substitution of Lu³⁺ improved the quality and emission intensity of red light of this double perovskite system and the composition optimized phosphor of K(Y_0.35Lu_0.6Eu_0.05)CaWO₆ exhibited great potential in the application of white LEDs.