Enhanced blue photoluminescence of B2O3-CaF2 glass-ceramics containing silver nanoparticles

We report photoluminescence (PL) measurements of B2O3-CaF2 glass-ceramics containing silver nanoparticles (NPs). The samples studied were prepared by the melting-quenching method followed by appropriate heat-treatment to form CaF2 and silver NPs. The techniques of X-rays diffraction (XRD), transmission electron microscopy (TEM), optical absorption and PL were applied to characterize the samples. The average size of the CaF2 nanocrystals was estimated in ≈20 nm while the silver NPs have sizes in the range 2-30 nm. By exciting the samples without silver NPs using light at 290 nm we observed a PL signal at ≈430 nm due to the presence of CaF2 nanocrystals. The experiments with the samples containing silver NPs revealed 1000% intensity enhancement of the blue PL that was attributed to the energy-transfer from the excited silver NPs to the CaF2 nanocrystals.