Structure and up-conversion luminescence in sol–gel derived Er3+–Yb3+ co-doped SiO2:PbF2 nano-glass–ceramics

Transparent oxyfluoride nano-glass–ceramics 90(SiO2)10(PbF2) co-doped with 0.3 Yb3+ and 0.1 Er3+ (mol%) have been prepared by thermal treatment of precursor sol–gel glasses. X-ray diffraction and high resolution transmission electron microscopy analysis pointed out a precipitation of cubic β-PbF2 nanocrystals of certain diameter in nano-glass–ceramics varying from 10 to 20 nm depending on heat treatment conditions. The incorporation of Yb3+ and Er3+ dopants in these nanocrystals has been confirmed by signatures of luminescence spectroscopy. Up-conversion luminescence pumped at 980 nm has been detected. Colour tuneability of up-conversion luminescence varying pump power has been analyzed in terms of standard chromaticity diagram. This tuneability opens applications for up-conversion phosphors and three-dimensional optical recording.