Enhanced luminescence and structure evolution of double perovskite (K, Na)LaMgWO6:Eu3+ phosphor for white LEDs

Double perovskite KLaMgWO 6 :Eu 3+ phosphors were successfully synthesized by an improved sol–gel method using citric acid and polyethylene glycol as complexing agents. The structure evolution and photoluminescence were systematically invested by X-ray diffraction, Rietveld refinement and fluorescence spectra. The structure of Eu 3+ doped samples was double-perovskite with space group C2/m . Enhanced luminescence properties were gotten by adding 5.0 wt% PEG. Na + with smaller radius was selected to substitute K + in this novel host. With increasing the concentration of Na + , the tolerance factors decreased and the structure of BO 6 tilted gradually and lowered structure symmetry. Then the emission intensity ratio of 5 D 0 – 7 F 2 / 5 D 0 – 7 F 1 transition increased and the red emission played the dominate role. Also the emission intensity was enhanced by increasing the concentration of Na + . The phosphors showed better color purity with better CIE chromaticity coordinates. Therefore the synthesized phosphors is a potential light conversion red material for light emitting diode.