Termometria óptica e conversão de energia em partículas de TiO2 dopadas com íons TR3+ obtidas pelo método sol-gel.

Abstract

Due to the search for alternative clean energy sources, among them, photovoltaic energy has stood out due to the use of solar radiation as a source for generating electricity. Titanium dioxide, an n-type semiconductor, is widely studied in these systems. For the development of this work, the sol-gel method was used to obtain TiO2 materials doped with 3% Eu3+, 0.04% Tb3+ and (0-1.5) % Yb3+ ions. By x-ray diffraction it was possible to identify peaks referring to the anatase and rutile phases of the materials. The crystallite sizes for the doped materials were between 10 and 15 nm. The rutile phase of TiO2 has a band gap (BG) of 3.0 eV and an anatase phase of 3.2 eV. The BGs obtained correspond to the TiO2 phases without significant changes after doping with RE3+ ions. The lifetime values (ms) were recorded under excitation at 405nm and emission at 615 nm arising from the 5D0 → 7F2 transition of the Eu3+ ion. The curves obtained with a monoexponentially profile indicate that the Eu3+ ions are in the same symmetry site within the TiO2 host lattice. With the doping of 0.1 mol% in mole of Yb3+ in the TiO2 matrix and heat treatment at 700°C it presented better results in crystallite size and luminescence, being, therefore, the promising material for energy conversion. The TiO2: Eu3% Tb0.04% Yb0.5% material presented thermometric characteristics comparable to the literature, highlighting the reversible luminescence property.