Ordering of fluorite-type phases in erbium-doped oxyfluoride glass ceramics

Abstract

In this study, novel transparent Er3+ doped glass ceramics were prepared from melt-quenched oxyfluoride glasses with general composition of Na2O-NaF-BaF2-YbF3-Al2O3-SiO2. The crystallization of fluorite (BaF2, BaF2-YbF3, NaF-BaF2-YbF3 and Na0.5-xYb0.5+xF2+2x) and distorted fluorite (rhombohedral Ba4Yb3F17 and tetragonal NaF-BaF2-YbF3) phases was analysed in glass ceramics with different BaF2 and YbF3 ratio. The phase composition and microstructure were investigated by X-ray diffraction (XRD) and scanning electron microscopy (SEM). Intense red upconversion luminescence (UCL) was detected under near-infrared excitation resulting from three photon upconversion followed by cross-relaxation between Er3+ and Yb3+ ions. The local environment of Er3+ ions in fluorite and distorted phases was analysed using site-selective spectroscopy. The Er3+ ions were found to act as nucleation centres in the glass ceramics containing BaF2. The phase transition from metastable fluorite to rhombohedrally and tetragonally distorted fluorite phases was detected using Er3+ ions as a probe. ----- / / / ----- This is the peer reviewed version of the following article: G. Krieke, A. Sarakovskis, M. Springis; Ordering of fluorite-type phases in erbium-doped oxyfluoride glass ceramics; Journal of the European Ceramic Society, 2018 38 (1), which has been published in final form at https://www.sciencedirect.com/science/article/abs/pii/S0955221917305769. This article may be used for non-commercial purposes in accordance with Elsevier Terms and Conditions for Sharing and Self-Archiving.