Spectroscopic properties and mechanism of Tm3+/Er3+/Yb3+co-doped oxyfluorogermanate glass ceramics containing BaF2 nanocrystals.

Transparent Tm3+/Er3+/Yb3+ co-doped oxyfluorogermanate glass ceramics containing BaF2 nanocrystals are prepared. Under excitation of a 980-nm laser diode (LD), compared with the glass before heat treatment, the Tm3+/Er3+/Yb3+co-doped oxyfluorogermanate glass ceramics can emit intense blue, green and red up-conversion luminescence and Stark-split peaks; X-ray diffraction (XRD) and transmission electron microscope (TEM) results show that BaF2 nanocrystals with an average diameter of 20 nm are precipitated from the glass matrix. Stark splitting of the up-conversion luminescence peaks in the glass ceramics indicates that Tm3+, Er3+ and (or) Yb3+ ions are incorporated into the BaF2 nanocrystals. The up-conversion luminescence intensities of Tm3+, Er3+ and the splitting degree of luminescence peaks in the glass ceramics increase significantly with the increase of heat treat temperature and heat treat time extension. In addition, the possible energy transfer process between rare earth ions and the up-conversion luminescence mechanism are also proposed. [ABSTRACT FROM AUTHOR]