Preparation and White Light Emission in Dy3+/Tb3+ Codoped Glass Ceramics Containing NaYF4 Nanocrystals

Dy3+/Tb3+ codoped oxyfluoride aluminosilicate glass ceramics containing alpha-NaYF4 nanocrystals were prepared by high temperature melt-quenching and subsequent thermal treatment method. The formation of alpha-NaYF4 nanocrystals were verified by XRD measurement. TEM micrograph demonstrated that spherical crystallites sized 20-30 nm distributed homogeneously among the glass matrix and EDX spectra indicated that Dy3+ ions was incorporated into the precipitated alpha-NaYF4 nanocrystals. Intense emission bands centered at 480 nm and 571 nm were observed in the Dy3+ doped precursor glass and glass ceramics and the intensity ratio of the yellow-to-blue emissions changed greatly. In the Dy3+/Tb3+ codoped glass ceramics, besides the emission bands from Dy3+ ions, strong green bands at the 540 nm, weak blue emission band at 485 nm and red emission at 615 nm of Tb3+ ions are simultaneously observed. The glass ceramic generates intense white light emission, indicative of their potential applications as the luminescent host for W-LEDs.