Influence of nanosized defects on photoluminescence efficiency of Er3+ ions co-doped with Au2 O3 in a lead boroselenate glass ceramic system: a novel approach using positron annihilation lifetime spectroscopy.

This study consists of the results of an investigation into the influence of the free-volume space (fv ) defects on luminescence efficiency (LE) of erbium ions in Au2 O3 -doped PbO-B2 O3 -SeO2 (PBS) glass ceramics. Glass ceramics containing fixed concentrations of Er3+ ions and varied concentrations of Au2 O3 were synthesized. X-ray diffraction studies indicated that the samples contained Au2 (SeO3 )3 crystalline phase and nano gold metallic particles. The concentration of defects entrenched in the glass ceramics estimated in terms of Au2 O3 content using positron annihilation lifetime spectroscopy measurement indicated the highest content in the glass ceramic containing 0.075 mol% of Au2 O3 . Optical absorption and the photoluminescence (PL) spectra of the glass ceramics were studied in the visible region. The observed increase of PL efficiency was attributed to the enhanced concentration of free-volume imperfections in the samples. A perfect correlation could be achieved between the free-volume fraction and the PL efficiency of erbium ions in these glass ceramics.