The objective of this project was to investigate the effect of addition of Ag2O on the spectroscopic properties of tellurite glasses and examine if silver nanoparticles can be grown in such glasses to enhance their spectroscopic properties. First, the impact of silver oxide concentration on the glass network was studied, and then the effect of heat-treatment duration on the growth of the silver nanoparticles was investigated.

Glasses with the composition (100-x-y) (70TeO2-20ZnO-10Bi2O3)-xAg2O-yEr2O3 with x = 0, 0.5, 1, 2 and 4 and y = 0 and 2.5 in mol% were prepared using the conventional melting quenching method. Afterwards glasses were heat-treated at Tg + 20 °C for 2, 5 and 17 hours to eventually grow the silver nanoparticles.

The progressive addition of Ag2O was found to modify the thermal and spectroscopic properties of the glass, increasing the thermal stability against crystallization due to the depolymerization of the tellurite network. However, even though the addition of Ag2O modified the glass network, it did not change the site of Er3+-ions. However, the highly Ag containing glasses exhibit lower intensity of upconversion when pumped at 980 nm suggesting that the Er-Er distance increases when adding Ag2O probably due to the depolymerization of the tellurite network.

A heat-treatment of the glasses at their Tg + 20 °C changed their color and their transparency due to crystallization, which was confirmed using XRD. The XRD pattern of the heat-treated glass exhibit similar sharp peaks which belong to the Bi4TeO8 crystals. In the XRD pattern and absorption spectra of the heat-treated glasses, there was no evidence of the precipitation of silver nanoparticles occurring during the heat-treatment. Additionally, the shapes of the Er3+ emission spectra remained similar after heat-treatment indicating that the Er3+ ions remained in the amorphous part of glass. However, the intensity of the conversion was found to increase after heat-treatment only in the low Ag containing glasses suggesting that the Er-Er distance decreases in the polymerized glasses due to the precipitation of Bi4TeO8 crystals. In the depolymerized network, the Er-Er distance does not seem to be impacted by the precipitation of Bi4TeO8 crystals.