Crystallization and optical properties of Tm3+/ Yb3+-co-doped KLaF4 glass-ceramics

Nanocrystallization of KLaF4 in a 70 SiO2-7 Al2 O3-16 K2O-7 LaF3 (mol%) glass co-doped with 0.2 mol% Tm2O3 and 0.5 mol% YbF3 was achieved by heat treatment above the glass transition temperature. KLaF4 nanocrystals of 6 nm precipitated and the crystal size was constant from 10 to 150 h of annealing time. The crystalline fraction achieved was very low, due to the drastic effect of the addition of dopants. The optical characterization of the obtained transparent glass and glass-ceramic showed a blue up-conversion emission due to an energy transfer mechanism involving two photons. However, there were no significant differences in the optical features between glass and glass-ceramic due to a low-crystallization degree. The role of dopant ions in the crystallization mechanism has been discussed.