Efeito da concentração de Eu3+ e do tratamento térmico nas propriedades estruturais e ópticas de matrizes de titanato de sódio almejando termometria óptica

Abstract

Luminescent thermometry remains an important area of research due to the growing demand for increasingly smaller temperature sensors, such as nanothermometers, that are increasingly efficient, for example, with higher emission and relative thermal sensitivity. Based on this, we developed in this work the structural and luminescent characterization of host matrices based on titanium oxide, more specifically, sodium trititanate (Na2Ti3O7) and sodium hexatitanate (Na2Ti6O13), doped with Eu3+ ions, to investigate their potential use as luminescence thermometers. The objective was to investigate the influence of Eu3+ doping and heat treatment (HT) on the structural and luminescent properties of sodium titanate matrices. In the X-ray diffractograms, it was observed that both the concentration of Eu3+ ions and the variation of HT influence the transformation of Na2Ti3O7 to Na2Ti6O13. In the luminescence spectra, it was found that the increase in concentration intensified the luminescence intensity, however the HT at high temperatures favored the decrease in intensity. The matrix of sodium titanate doped with 5 wt.% and with HT at 500 ºC showed the highest luminescence. This same behavior was observed in the lifetime measurements. In order to evaluate the potential of this material as a luminescent thermal sensor, measurements of luminescence as a function of temperature were performed. The maximum relative thermal sensitivity obtained was approximately 0.34 %C-1 at 25 °C, which is a value comparable to other luminescent materials present in the literature. Thus, we demonstrate that this material, specifically sodium hexatitanate doped with 5.0 wt.% Eu3+, is a potential candidate for luminescent thermometry.