Banca de QUALIFICAÇÃO: AMANDA LUCENA DE MEDEIROS

Uma banca de QUALIFICAÇÃO de DOUTORADO foi cadastrada pelo programa.
DISCENTE : AMANDA LUCENA DE MEDEIROS
DATA : 12/09/2019
HORA: 09:00
LOCAL: Auditório do NTCPP
TÍTULO:

EFFECT OF SYNTHESIS TIME AND CHARACTERIZATION OF CE1-XGDXO2-δ NANOPARTICLES OBTAINED BY THE MICROWAVE-ASSISTED HYDROTERMAL METHOD FOR SOFC ELECTROLYTES

PALAVRAS-CHAVES:

SOFC, microwave-assisted hydrothermal synthesis, gadolinium-doped ceria, electrolyte

PÁGINAS: 120
GRANDE ÁREA: Engenharias
ÁREA: Engenharia de Materiais e Metalúrgica
SUBÁREA: Materiais Não-Metálicos
ESPECIALIDADE: Cerâmicos
RESUMO:

High operating temperatures result in important properties to solid oxide fuel cells (SOFCs), however, allied to high operating and manufacturing costs. This conditions this technology to specialized materials for such operating conditions, which limits its service life. Alternatively, the commercial viability of SOFCs depends on the lowering of their operating temperature, especially that of the solid electrolyte. Rare earth-doped ceria-based electrolytes are the best alternative, as they have higher electrical conductivity than zirconia-yttria at lower operating temperatures. However, some difficulties remain unresolved in obtaining ceria-based solid electrolytes, such as the low sinterability of the material and the low conductivity of grain boundaries, usually associated with the presence of impurities. In this context, the present work studies the influence of the synthesis time to obtain gadolinium-doped ceria nanoparticles using the microwave-assisted hydrothermal method, and the structural and electrical properties of the resulting powders. Samples of Ce1-xGdxO2-δ (x = 0.1, 0.2 and 0.3) were synthesized, with hydrothermal treatment time varying from 15, 30, 45 to 60 minutes. The obtained materials were characterized by density measurements, FRX, XRD, TG, BET, TPR, SEM-FEG, TEM and impedance spectroscopy. The results showed that shorter hydrothermal processing times result in nanometer powders with smaller particle sizes and high specific surface area. Despite the introduction of Gd into the cerium oxide network, all powders crystallized in the fluorite-like structure of ceria. It was observed that the concentration of the dopant has a direct influence on the specific surface area and other properties of synthesized powders. The powders present a strong tendency of agglomeration, which directly influences the densification of the powders. Impedance spectroscopy results indicate that increasing dopant concentration decreases grain conductivity due to increased interaction of doping defects.

MEMBROS DA BANCA:
Presidente - 1298936 - ANTONIO EDUARDO MARTINELLI
Externo à Instituição - DANIEL ARAÚJO DE MACEDO - UFPB
Interno - 1350249 - RUBENS MARIBONDO DO NASCIMENTO