Luminescence behavior of $Er3+$ doped glass ceramics containing $Sr2RF7$ $(R=Y,Gd,La)$ nanocrystals

The luminescence behaviors of $Er3+$ doped glass ceramics containing $Sr2RF7$ $(R=Y,Gd,La)$ nanocrystals were investigated. The formation of $Sr2RF7$ nanocrystals in the glass ceramics was confirmed by x-ray diffraction and high resolution transmission electron microscopy. Energy dispersive x-ray spectroscopy analysis showed that the $Er3+$ ions were efficiently incorporated in $Sr2GdF7$ nanocrystals. The efficient upconversion luminescence of the $Er3+$ in the glass ceramics can be observed. The lifetime of the $Er3+$ in the glass ceramics was found to be much longer than that in the glass due to the lower phonon energy of fluoride crystals when $Er3+$ entered efficiently fluoride crystals in the glass ceramics.