Site selection spectroscopy in Eu3 +-doped lanthanum fluorozirconate glass and glass-ceramic

Abstract The optical properties of Eu 3 + -doped glass and transparent glass-ceramic with composition (in mol%) 70.2ZrF 4 –23.4LaF 3 –0.6AlF 3 –5.8GaF 3 were investigated by site selective spectroscopy in order to study the effect of ceramization on the symmetry of Eu 3 + sites. The glass-ceramic obtained after thermal treatment of the glass ZLAG contains a unique crystalline phase of unknown structure. The analysis and comparison of FLN spectra in these materials are presented and different classes of sites are discussed. We found the presence of two main site distributions for Eu 3 + ions of equivalent symmetry (C 2v or lower) in the glass and two sites of different symmetry (C 2v or lower and C 4v or lower) in the glass-ceramic (GC). The estimated average crystal field strength for glass and GC decreases with the 5 D 0  →  7 F 0 energy. The results suggest that the two kinds of sites identified in the glass correspond to Eu 3 + ions in and out of the former network. Decay-time measurements of 5 D 0 level of Eu 3 + evidenced energy transfer between high and low energy sites and showed an increase of lifetime from the glass to the glass-ceramic.