resumo
Gd-doped ceria electrolytes (GDC, 10 at.% Gd) were prepared using a eutectic mixture of Li and Na carbonates as sintering aid (NLC - 0, 1, 3 and 5 mol%), using two processing routes (ceramic and chemical). Structural and microstructural characterization provided no evidence for significant solubility of alkali metal cations in GDC. Materials sintered at 1100 degrees C/4 h were similar in densification ( > 95%) and microstructure to those obtained from a commercial powder sintered at 1500 degrees C/4 h. Impedance spectroscopy in air (200-600 degrees C) and as a function of oxygen partial pressure (from 0.21 to about 10(-25) atm, 600-750 degrees C) showed that the low temperature conductivity of materials prepared using chemical synthesis surpassed the conductivity of a commercial GDC due to higher grain boundary conductivity. The estimated n-type conductivity of materials with NLC was also slightly higher than for pure GDC. The role of sintering aid and processing routes is discussed taking into consideration decomposition and volatilization of alkali salts.
palavras-chave
GRAIN-BOUNDARY CONDUCTIVITY; GADOLINIA-DOPED CERIA; ELECTRICAL-PROPERTIES; ELECTROCHEMICAL PROPERTIES; ELECTRONIC CONDUCTIVITY; TRANSPORT-PROPERTIES; SOLID ELECTROLYTES; OXIDE ADDITION; CERAMICS LN; DENSIFICATION
categoria
Chemistry; Physics
autores
Grilo, JPF; Macedo, DA; Nascimento, RM; Marques, FMB
nossos autores
Fernando Manuel Bico Marques
Professor Catedrático
João Grilo
Investigador JúniorProjectos
agradecimentos
This work was funded by projects CO2ZERO (POCI-01-0145-FEDER-016654 - PTDC/CTM-CER/6732/2014), MOCO3 - (M-ERA.NET2 2016 - MOCO3-0009/2016), and CICECO-Aveiro Institute of Materials (FCT Ref. UID/CTM/50011/2019), financed by national (Portugal) funds through the FCT/MCTES, and when applicable co-financed by FEDER under the COMPETE 2020 Program. This work was also developed with funding from CNPq (Program Ciencia sem Fronteiras, Brazil).