Blue and orange emission from Ce3+ and Yb2+ doped KNa3Al4Si4O16 phosphor: A detailed study of the luminescence mechanism

Abstract

Blue and orange-emitting, KNa3-xSi4Al4O16:xCe(3+) and KNa3-ySi4Al4O16:yYb(2+) were synthesized through solid-state reaction. Analyses of structural properties of the phosphors were performed through Rietveld refinement of the XRD pattern, and the luminescence properties were analyzed by activation with Ce3+ and Yb2+ ions. On excitation with 397 nm source, photoluminescence (PL) spectra Ce3+ activated compound was found to be a typical blue asymmetric emission band originating from 5d(1) -> 4f(1)(F-2(7/2) and F-2(5/2)) transitions of Ce3+ ions. On exciting with 442 nm source, Yb2+ activated samples showed an orange broad emission band, due to transitions in the 4f(13)5d(1) and 4f(14) levels. The temperature dependence of PL was analyzed for both phosphors, and Yb2+ doped compound showed a rapid thermal quenching of luminescence, compared to Ce3+ doped compound, as is expected for higher stokes shift emission bands.