Crystallisation effects on rare earth dopants in oxyfluoride glass ceramics

Transparent oxyfluoride glass-ceramic materials are of significant interest for the production of new optoelectronic devices. In this paper we report measurements of the detailed spectroscopy of rare earth dopants in both an oxyfluoride transparent glass ceramic and its glass precursor. We show that several spectroscopically different sites exist for the rare earth even in the glass precursor material, where a significant amount of the rare earth is already coordinated with fluorine. In the glass-ceramic material, these glassy fluorine-coordinated sites are replaced with crystalline sites, but a significant fraction of the rare earth ions are still within the glass phase. The fraction of rare earth ion that is incorporated into the crystalline phase is estimated from the rare earth spectroscopy, and the role of the rare earth coordination in the precursor glass is discussed. (C) 2002 Elsevier Science B.V. All rights reserved.