Structure and Optical Spectroscopy of Eu-Doped Glass Ceramics Containing GdF3 Nanocrystals

Transparent glass ceramics containing hexagonal GdF3 nanocrystals were fabricated by melt-quenching and subsequent heating of glass with composition of 44SiO(2)-28Al(2)O(3)-17NaF-11GdF(3). The GdF3 nanocrystals with mean size of 6 nm were precipitated during quenching of the melt. Increasing the heating temperature of the quenched sample resulted in the further precipitation and growth of the GdF3 particles. The room temperature photoluminescence spectra of the glass ceramic excited at 398 nm show that, in addition to the characteristic sharp emissions of Eu3+ ions, an intense wide blue emission band ascribing to the Eu3+ 5d -> 4f transition also appeared. The obvious Stark splitting of the emissions, the low forced electric dipole D-5(0) -> F-7(2) transition, and the long decay lifetimes of Eu3+ evidenced the partition of Eu3+ ions into the GdF3 nanocrystals, while Eu2+ ions were found to reside in the glass matrix. The excitation and emission spectra demonstrated that the excitation energy of Gd3+ was transferred to both Eul+ and Eu3+.