Enhancement of photoluminescence and upconversion in Er-Yb codoped nanocrystalline glass-ceramics

Oxyfluoride glass ceramics containing CaF2 nanocrystals were prepared with dopants of Er2O3 and Yb2O3 through melt-quenching and proper thermal treatments. Emission spectra, emission decay and energy dispersive X-ray spectroscopy analysis of the glass ceramics indicated the incorporation of rare earth ions into CaF2 nanocrystals. Photoluminescence intensity of the glass-ceramics has been increased more than a hundred times compared with that of the precursor glass. We also obtained enormous enhancement in upconversion emission and relative population increase of the F-4(9/2) level by energy transfer process under excitation at 980 nm in resonance with the F-2(5/2) of Yb3+ and I-4(11/2) of Er3+ ions. (C) 2012 Elsevier B.V. All rights reserved.