Banca de DEFESA: DAIANE MARIA MEDEIROS DA SILVA

Uma banca de DEFESA de MESTRADO foi cadastrada pelo programa.
STUDENT : DAIANE MARIA MEDEIROS DA SILVA
DATE: 05/08/2022
TIME: 13:30
LOCAL: Instituto de Física (remoto)
TITLE:

Effect of Eu³⁺ concentration and heat treatment on structural and optical properties of sodium titanate matrices targeting optical thermometry

KEY WORDS:

Sodium Trititanate. Sodium Hexatitanate. Luminescent Thermometry. Europium.

PAGES: 62
BIG AREA: Ciências Exatas e da Terra
AREA: Física
SUMMARY:

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 like luminescent thermometers. Four Eu³⁺concentrations were used: 0.5, 1.0, 5.0, and 10.0 mol%. Furthermore, the samples were submitted to four different heat treatment (HT) temperatures: 250 °C, 500 °C, 650 °C, and 800 °C. The objective was to investigate the influence of Eu³⁺doping and HT on the structural and luminescent properties of these samples. As a result, in general, we found that in the undoped samples we had a mixture of phases that were not identified. In the samples doped with Eu³⁺, it was found that the incorporation of Eu³⁺ favored the formation of the Na₂Ti₆O₁₃ phase. It was also observed that increasing the HT temperature caused them to change from an amorphous phase configuration, with the mixture of the Na₂Ti₃O₇ and Na₂Ti₆O₁₃ phases, to a pure crystalline phase, corresponding to the Na₂Ti₆O₁₃ phase at the HT temperature of 800 °C. Regarding the luminescent properties, it was found that, in general, the HT samples at 250 °C, 500 °C and 650 °C that presented the highest luminescence were those doped with 10.0 mol% of Eu³⁺. However, for the HT temperature of 800 °C, the highest luminescence observed was in the sample doped with 5.0 mol% of Eu³⁺, whose maximum relative thermal sensitivity obtained was approximately 0.34 %C^-1 at 25 °C, the which is a value comparable to other luminescent materials present in the literature. Thus, these samples are potential candidates for luminescent thermometry.

BANKING MEMBERS:
Presidente - 1545463 - CARLOS JACINTO DA SILVA
Interna - 1247925 - ANIELLE CHRISTINE ALMEIDA SILVA
Interno - 2579019 - WAGNER FERREIRA DA SILVA
Externo à Instituição - NELSON GUILHERME CASTELLI ASTRATH