Up-conversion of Er super(3+)/Yb super(3+) co-doped transparent glass-ceramics containing Ba sub(2)LaF sub(7) nanocrystals

The up-conversion of Er super(3+)/YU super(3+) co-doped transparent glass-ceramics 50SiO sub(2)-10AlF sub(3)- sub(5)TiO sub(2)-30BaF sub(2)-4LaF sub(3)-0.5ErF sub(3 )-0 .5YbF sub(3) containing Ba sub(2)LaF sub(7) nanocrystals under the changing of heat treatment temperature and time were investigated. The Ba sub(2)LaF sub(7) nanocrystals precipitated from the glass matrix was confirmed by X-ray diffraction (XRD). The structural investigation carried out by XRD and transmission electron microscopy (TEM) evidenced the formation of cubic Ba sub(2)LaF sub(7) nanocrystals with crystal size of about 14 nm. Comparing with the samples before heat treatment, the high efficiency up-conversion emission of Er super(3+)/Yb super(3+) co-doped samples was observed in the glass-ceramics under 980 nm laser diode excitation. The increase in red emission intensity bands was stronger than the green bands when the crystal size increased. The mechanism for the up-conversion process in the glass-ceramics and the reasons for the increase of Er super(3+)/Yb super(3+) co-doped up-conversion intensity after heat treatment were discussed.