This work investigates the optical properties of Yb3+ ions doped GeO2-PbO glasses containing Ag nanoclusters (NCs), produced by the melt-quenching technique. The lack in the literature regarding the energy transfer (ET) between these species in these glasses motivated the present work. Tunable visible emission occurs from blue to orange depending on the Yb3+ concentration which affects the size of the Ag NCs, as observed by transmission electron microscopy. The ET mechanism from Ag NCs to Yb3+ ions (2F7/2 → 2F5/2) was attributed to the S1→T1 decay (spin-forbidden electronic transition between singlet–triplet states) and was corroborated by fast and slow lifetime decrease (at 550 nm) of Ag NCs and photoluminescence (PL) growth at 980 nm, for excitations at 355 and 405 nm. The sample with the highest Yb3+ concentration exhibits the highest PL growth under 355 nm excitation, whereas at 410 nm it is the sample with the lowest concentration. The restriction of Yb3+ ions to the growth of NCs is responsible for these effects. Thus, higher Yb3+ concentration forms smaller Ag NCs, whose excitation at 355 nm leads to more efficient ET to Yb3+ ions compared to 410 nm. These findings have potential applications in the visible to near-infrared regions, such as tunable CW laser sources and photovoltaic devices.

The purpose of this work is to produce and characterize GeO2-PbO (GP) glass samples codoped with Yb 3+ ions and silver nanoclusters (silver NCs), and to study the mechanisms of energy transfer between them. The glass samples were produced by the melt-quenching technique followed by rapid cooling to relieve internal stress; additional treatments were performed to promote the growth of silver NCs. The silver NCs and Yb 3+ ions emissions were analyzed with excitation at different wavelengths. The silver NCs emission showed tunable light emission in the visible region of the electromagnetic spectrum for different concentrations of Yb 3+ and also for excitations in the range of 355-410 nm. The dependence of emission tuning on the concentration of Yb 3+ is due to the fact that they normally restrict the size of silver NCs. By analyzing the silver NCs and Yb 3+ ions lifetime, and measuring luminescence, energy transfer mechanisms between them were studied and confirmed. Energy transfer between silver NCs and Yb 3+ ions at 980 nm was observed for excitations at 355 and 410 nm. In the first case, an increase of over 100% in the emission of Yb 3+ ions was observed for the sample 4.5% AgNO3/4.5% Yb2O3, and in the second case, an increase of over 1000% was observed for the sample 4.5% AgNO3/2% Yb2O3 (weight total %). Larger silver NCs are more adequately excited at longer wavelengths, which explains the efficient energy transfer mechanisms for the 4.5% AgNO3/2% Yb2O3 sample when excited at 410 nm. Energy transfer occurs through the S1→T1 decays (spin-forbidden electronic transition between singlet-triplet states) of the silver NCs to the Yb 3+ ions. A decrease in the short and long lifetimes of the silver NCs at 550 nm (for excitations at 355, 380 and 405 nm) and 800 nm (for excitation at 405 nm) was observed in samples co-doped with Yb 3+ ions, compared to the sample doped only with AgNO3, supporting the mentioned energy transfer mechanism. To verify the influence of Yb 3+ ions on the formation of silver NCs, transmission electron microscopy (TEM) measurements were performed, which showed a change in the average size when added Yb 3+ ions (the average size changes from 4.7 to 3.0 and 2.2 nm). These results confirm for the first time the possibility of producing GP glasses with silver NCs and Yb 3+ ions, and the energy transfer mechanism between them, with applications for photonic devices such as devices with tunable light emission, solar cells, and broadband visible light sources.

Germanate and tellurite glasses doped with Eu3+ ions and Au/Ag nanoparticles were produced and optical and electrical characterizations were made. Efficiency enhancement of Si solar cell covered with these glasses was observed.

A glass flask obtained of pickled food was developed as bulb with intern vacuum to tests of encapsulation method for electroluminescent devices. Two metal valves to vacuum or insert inert gas, one pressure gauge (with high or low pressures) and one printed circuit board with copper strips for electrical connections were adapted to the glass flask lid and sealed with epoxy. In the first investigation, intern vacuum was carried out and the possible variation of intern pressure was observed by elapsed time (for seven days). In the second investigation, four incandescent lamps (12 V and 10 W) were used without outer bulb to obtain the tungsten filaments that were polarized under vacuum atmosphere at different situations. After seven days, only an insignificant increase of intern pressure was observed. The tungsten filaments were polarized at least 40 times inside the bulb with intern pressure at 101325 Pa (or 76 cm.Hg), while outside the bulb (at room pressure) only two polarizations with significant degradation were obtained. A layer of tungsten oxide (WO 2) with greenish yellow color was formed on the surface of the tungsten filament which was obtained by microscopies and confirmed by EDXS measurement.