Enhanced upconversion emissions in Ho3Â +/Yb3Â + codoped tellurite glasses containing silver NPs

Ho3 +/Yb3 + codoped zinc-tellurite glasses containing silver nanoparticles (NPs) were prepared using the conventional melt-quenching technique. The detailed effect of silver NPs on the upconversion emission of Ho3 +, thermal stability and structure behavior of glass hosts was investigated from the measured absorption spectra, upconversion emission spectra, differential scanning calorimeter (DSC) curves, X-ray diffraction (XRD) patterns and transmission electron microscopy (TEM) images. Two frequency upconversion emission bands centered at 546 nm (green) and 657 nm (red) corresponding to Ho3 + transitions of 5F4(5S2) → 5I8 and 5F5 → 5I8, respectively, are simultaneously observed under the 980 nm excitation at room temperature. It is shown that the introduction of silver NPs can further improve the upconversion emissions of Ho3 +and thermal stability of glass host, while the glass structure maintains the amorphous nature. The enhanced upconversion emission is mainly attributed to the increased local electric field around Ho3 +induced by localized surface plasmon resonance (LSPR) effect of silver NPs. Furthermore, the energy transfer (ET) mechanism from Yb3 +:2F5/2 level to Ho3 +:5I6 level is quantitatively analyzed by calculating relevant micro- parameters and phonon contribution ratio.