Transferência de energia e geração de luz policromática em vidros dopados com Tm3+/Ho3+ e Er3+/Eu3+

Abstract

In this dissertation we studied process of energy transfer and generation of polychromatic light by the process of energy upconversion in fluorogermanate glasses doped with Tm3+, Ho3+, Er3+ and Eu3+. The energy transfer process from Tm3+ to Ho3+ generated emissions in the visible region, in the primary colors red, green and blue, as well as infrared, when the samples were excited at 1200 nm. Emissions from the Tm3+ ion were responsible for blue (480 nm) and red (650 nm), and infrared (800 nm). The green emission (540 nm) is associated with the Ho3+ ion, which was possible through the energy upconversion mechanism, mediated by energy transfer from Tm3+ to Ho3+. In the samples doped with Erbium and Europium green (520 and 545 nm) and red (650 nm) emissions were obtained for Er3+ monodoped samples, while emissions in yellow (590 nm), orange (610 nm) and red (700 nm) initially associated with the Eu3+ ion, occured only for the codoped samples (Er3+/Eu3+), through the energy transfer process from Er3+ to Eu3+ when excited at 980 nm. With triple doping ((Er3+/Eu3+/Yb3+), we noticed the increase of the Er3+ and Eu3+ ions in the red, green and blue regions of the visible spectrum, which indicated a promising use of these samples as white light-emitting phosphors based on upward energy conversion.