Novel emission bands of Na2TiF6:Mn4+ phosphors induced by the cation exchange method

摘要： A series of Na2TiF6:xMn4+ samples were prepared by the cation exchange method. Visible QC behavior and the strongest ZPL peaks were observed for these samples. The characteristic of the visible QC behavior is that PL intensity at 620 nm is 1.61 times as high as PLE intensity at 476 nm. The mechanisms of these phenomena were discussed, and the color purity, crystal-field and nephelauxetic effect, the critical distance and the multipolar interaction for the samples were determined. The result shows that the Mn4+ ions are located at a strong crystal field and the concentration quenching of Mn4+ is from the quadrupole-quadrupole interaction. The slightly increase of nephelauxetic ratio causes the slightly blue shift of emission. The color-purity and chromaticity coordinates of the optimal sample suggests that the strongest ZPL makes its red emission with high color-purity. Thus, Na2TiF6:0.08Mn4+ is a potential red-emitting phosphor for blue light-based WLEDs.