Caracterização óptica de vidros PZABP dopados com Tm3+, Yb3+ e nanopartículas de ZnTe

Abstract

Phosphate glasses are great rare-earth hosts for production of active means of lasers because their very high solubility for these ions, thus arousing great interest in the technology field. These glasses have high thermal expansion coefficient and low glass transition temperature when compared to silicate or borate glasses. However, its low chemical durability in humid environments and high phonons energy limited their applications. The addition of Al2O3 in phosphate glasses increases its humidity resistance, increases the glass transition temperature and decreases the thermal expansion coefficient, by acting directly on the phosphate glass network. In this work, we characterized phosphate glasses doped with rare-earth ions of Thulium (Tm3+) and Ytterbium (Y b3+), and tellurium (Te) to form nanocrystals of zinc telluride (ZnTe) using spectroscopy. Our matrix composition was 60P2O5 + 15ZnO + 5Al2O3 +10BaO + 10PbO [mol%] (PZABP). We analyzed four sets of samples: PZABP + xTm; PZABP +2Yb + xTm; PZABP +1Te + xTm e PZABP +1Te +2Yb + xTm (where x = 0,01; 0,05; 0,1; 0,5; 1,0; 2,0; 3,0 [wt%]). The characterization involved ultraviolet, visible an infrared absorption to identify the absorption peaks of each dopant, visible and infrared photoluminescence to identify and compare the emission peaks of each dopant, and time resolved photoluminescence of the excited state of the rare-earth Y b3+ to evaluate its lifetime. Our results indicate that only samples doped with Y b3+ had emission of Tm3+ in the visible region. We believe that the presence of Y b3+ is required to promote the energy transfer to the Tm3+ and enable its emission, because the matrix has a high phonon energy. We also compared the results obtained for matrices with and without nanocrystals of ZnTe and it shows that the nanocrystals ZnTe intensify the emission of ions Y b3+. Our results indicate that the doped phosphate glasses studied are not suitable for application as active laser medium on the blue region of the spectra. However, the results pointed to new applications with the combination of Ytterbium and nanocrystals of ZnTe as dopants to phosphate glasses.