Upconversion properties of Er3+-doped oxyfluoride glass-ceramics containing SrF2nanocrystals

Abstract

ABSTRACT Er 3+ -doped oxyfluoride glass and glass-ceramics containing SrF 2 nanocrystals have been prepared and investigated their spectroscopic and luminescence prop erties. The formation of SrF 2 nanocrystals in glass-ceramics were confirmed by X-ray diffraction (XRD) and transmission electron microscopy (TEM). Judd-Ofelt parameters have been evaluated from absorption spectra of the Er 3+ -doped glass, which in turn used to predict ra diative properties for the fluorescent levels of Er 3+ ions. The intensities of both Stokes and upconversion (anti- Stokes) emissions significantly increase with increase of the size of the fluoride crystals in the glass matrix. The mechanism of green and red upconversion emissions have been ascribed to two photon processes. The lifetime of the 4 S 3/2 level of the Er 3+ ions in glass-ceramics is found to be slightly higher than that of the counter glass, which may be due to the incorporation of Er 3+ ions into the low phonon sites of SrF 2 nanocrystals. Keywords: Oxyfluoride glass-ceramics; SrF