Banca de DEFESA: AMANDA LUCENA DE MEDEIROS

Uma banca de DEFESA de DOUTORADO foi cadastrada pelo programa.
DISCENTE : AMANDA LUCENA DE MEDEIROS
DATA : 30/09/2019
HORA: 09:00
LOCAL: Laboratório de Cimentos
TÍTULO:

Microwave-assisted hydrothermal synthesis of Ce1-XGdXO2-δ and characterization aiming at its application as SOFC electrolytes.

PALAVRAS-CHAVES:

SOFC, Microwave-assisted hydrothermal synthesis, gadolinium-doped céria, electrolyte

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

Fuel cell electrolytes require high operating temperatures, resulting in high operating and manufacturing costs. Materials based on rare earth doped ceria are an 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 aimed at studying the microwave-assisted hydrothermal synthesis to obtain Ce1-xGdxO2-δ nanoparticles, and to analyze the compatibility of the properties of the resulting powders with those required by SOFC electrolytes. Samples of Ce1-xGdxO2-δ (x = 0.1, 0.2 and 0.3) were synthesized. The obtained materials were characterized by density measurements, FRX, XRD, TG, BET, SEM-FEG, TEM and impedance spectroscopy. The results showed that shorter hydrothermal processing times result in nanometer powders with smaller particle sizes, high specific surface area, and strong tendency to agglomeration, which directly influences the densification of the obtained materials. Despite the introduction of Gd into the cerium oxide lattice, all powders crystallized into the fluorite-like structure, typical of ceria. The impedance spectroscopy results indicate that the increase of the dopant concentration decreases the grain conductivity, due to the increase of the interaction of the doping defects, and that the impurities presented act as ionic blocking agents.

MEMBROS DA BANCA:
Presidente - 1298936 - ANTONIO EDUARDO MARTINELLI
Interno - 1350249 - RUBENS MARIBONDO DO NASCIMENTO
Externo à Instituição - ARMANDO MONTE MENDES - UFRN
Externo à Instituição - DANIEL ARAÚJO DE MACEDO - UFPB
Externo à Instituição - FAUSTHON FRED DA SILVA - UFPB