Desenvolvimento de processo de produção de>i< nanocluster>/i< de prata em vidros GeO>sub<2>/sub<-PbO com e sem íons de Yb>sup<3+>/sup< e Tm>sup<3+>/sup<

Abstract

The present work shows the development of technology for the production of silver (Ag) nanoclusters in GeO2-PbO glasses codoped with Tm 3+ and Yb 3+ ions and doped with Tm 3+ ions. The samples were produced by the melt quenching followed by rapid cooling, using a temperature lower than the glass transition one for the heat treatment, in order to favor the formation of Ag nanoclusters; the samples were characterized by measurements of absorption, luminescence, lifetime and transmission electron microscopy. The absorption measurements identified the incorporation of rare-earth ions in the trivalent form. The identification of the aforementioned nanoclusters and amorphous structure was performed by transmission electron microscopy and electron diffraction analysis, respectively; Through luminescence measurements made under different conditions (different lasers operating at 355 and ~ 400 nm, UV lamp and fluorimeter) the emission of Ag nanoclusters and correlation with their concentration and excitation wavelength were studied. The energy transfer mechanism between the nanoclusters and the aforementioned Tm 3+ and Yb 3+ ions was studied with the aid of luminescence and lifetime measurements. Different light emission from Ag nanoclusters at different excitation wavelengths (340-400 nm) indicate the formation of nanoclusters of different sizes; the same occurs when we increase the concentration of Ag nanoclusters, which leads to an increase in their dimensions and luminescence at longer wavelengths. It should be added that in the presence of rare-earth ions, it was possible to observe the emission of white light for excitation at 365 nm, performed by a UV lamp. Energy transfer from nanoclusters to Tm 3+ ions was confirmed by the luminescence growth at 800 nm, being more significant in the absence of Yb 3+ ions, for excitations at 380 and 400 nm. The decrease in the lifetimes of Ag nanoclusters and the increase in the lifetimes of the Tm 3+ ions, corroborated these energy transfers. The energy transfer from the nanoclusters to the Yb 3+ ions(980nm) were also observed through the luminescence and lifetime results, for excitation at ~ 400 nm, being more significant for the highest concentration of nanoclusters. The present results demonstrate for the first time the possibility of producing Ag nanoclusters in GeO2-PbO glasses, energy transfer to rare-earth ions, corroborating the potential of these materials for photonics and opens perspectives for further studies with different rare-earth ions.