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

Blue and orange-emitting, KNa 3− x Si 4 Al 4 O 16 : x Ce 3+ and KNa 3− y Si 4 Al 4 O 16 : y Yb 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 Ce 3+ and Yb 2+ ions. On excitation with 397 nm source, photoluminescence (PL) spectra Ce 3+ activated compound was found to be a typical blue asymmetric emission band originating from 5d 1 → 4 f 1 ( 2 F 7/2 and 2 F 5/2 ) transitions of Ce 3+ ions. On exciting with 442 nm source, Yb 2+ activated samples showed an orange broad emission band, due to transitions in the 4 f 13 5 d 1 and 4 f 14 levels. The temperature dependence of PL was analyzed for both phosphors, and Yb 2+ doped compound showed a rapid thermal quenching of luminescence, compared to Ce 3+ doped compound, as is expected for higher stokes shift emission bands. [ABSTRACT FROM AUTHOR]