Banca de DEFESA: FLÁVIO JOSÉ DE ABREU MOURA

Uma banca de DEFESA de MESTRADO foi cadastrada pelo programa.
STUDENT : FLÁVIO JOSÉ DE ABREU MOURA
DATE: 10/03/2023
TIME: 09:00
LOCAL: Programa de Pós-Graduação em Ciência de Materiais
TITLE:

NEW NANOCOMPOSITES OF SILICA AEROGEL WITH LANTANIDE OXIDES FOR EMISSION OF INTENSE WHITE LIGHT BY UPWARD ENERGY CONVERSION

KEY WORDS:

Upconversion; Lanthanide Oxides; Hybrids; Thermal Emission; White Light.

PAGES: 93
BIG AREA: Outra
AREA: Multidisciplinar
SUMMARY:

Several studies with lanthanide oxides have been attempting to develop materials for efficient energy upconversion, due to its innumerous possibilities of applications in the field of photovoltaic energy. These efficient materials will be able to take advantage of a large part of the solar spectrum (infrared) that is lost in conventional photovoltaic panels and convert it into visible light, increasing the efficiency of these panels. Thus, the present work aimed at investigating the influence of a thermal insulating matrix coated with PrO2 and Yb2O3 oxides exposed to a near-infrared (NIR) laser in upconversion processes. The oxides and nanocomposites with silica, SiO2/PrO2 and SiO2/Yb2O3, were synthesized via Pechini method. These materials exhibit intense absorption from the visible to NIR, resulting in high temperatures upon excitation at 980 nm with power densities ranging from 0,5 to 4,5 W cm−2 and emitting very bright white light by thermal irradiation. The steady-state temperatures were estimated by the blackbody (Planck) distribution, which were higher than 2000 K for the SiO2/Yb2O3 hybrids under low pressures. It was also observed that for the SiO2/PrO2 hybrids, the concentration of oxides did not affect the emission intensities, in contrast to the SiO2/Yb2O3 hybrids for which the concentration increase directly affects the rise of the emission intensity for the same excitation power density. In general, the increase in excitation power results in an increase in local temperature and, consequently, the brightness of the broadband emission intensity, ascribed to blackbody emission. For the SiO2/Yb2O3 hybrids, it was observed the formation of micro spheres under irradiation at 980 nm, which could lead to a new synthetic approach to ytterbium oxides. Additional efforts are needed to develop these new materials into efficient thermophotovoltaic applications. However, it was shown that the incorporation of thermal insulating materials with high chemical stability still make viable the process of photoinduced thermal bright emissions.

COMMITTEE MEMBERS:
Externo à Instituição - LEONIS LOURENÇO DA LUZ - UFPE
Externo à Instituição - Luís António Ferreira Martins Dias Carlos - UA
Interno - 1130924 - OSCAR MANOEL LOUREIRO MALTA