Optical and upconversion properties of Er~(3+)-doped oxyfluoride transparent glass-ceramics containing SrF_2 nanocrystals

摘要

Er~(3+)-doped oxyfluoride transparent glass and glass-ceramics (GCs) containing SrF_2 nanocrystals were prepared and their spectroscopic properties were investigated. The formation of SrF_2 nanocrystals in GCs has been confirmed by x-ray diffraction (XRD) and transmission electron microscopy. The Judd-Ofelt (JO) parameters have been evaluated from absorption spectra of the Er~(3+)-doped glass and GCs, which are used to predict radiative properties for some important luminescence levels of Er~(3+) ions in glass and GCs. The XRD and JO parameters suggest that the Er~(3+) ions are progressively incorporated into the SrF_2 nanocrystals in the GCs compared with glass. The up-conversion luminescence intensity increases significantly in GCs with increase in time of thermal treatment. The lifetime of the ~4S_(3/2) level of the Er~(3+) ions in GCs is found to be slightly higher than that in the glass due to the incorporation of Er~(3+) ions into the lower phonon energy of SrF_2 nanocrystals in the GCs.