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Design of Electroceramics for Solid Oxides Fuel Cell Applications: Playing with Ceria
Author(s) -
Esposito Vincenzo,
Traversa Enrico
Publication year - 2008
Publication title -
journal of the american ceramic society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.9
H-Index - 196
eISSN - 1551-2916
pISSN - 0002-7820
DOI - 10.1111/j.1551-2916.2008.02347.x
Subject(s) - materials science , sintering , grain boundary , dopant , microstructure , grain size , electrical resistivity and conductivity , coprecipitation , grain boundary diffusion coefficient , chemical engineering , electroceramics , grain growth , mineralogy , doping , metallurgy , fabrication , chemistry , optoelectronics , medicine , microfabrication , alternative medicine , pathology , electrical engineering , engineering
Nanostructured samaria‐ and gadolinia‐doped ceria (SDC and GDC) powders were synthesized at low temperature (400°C) using diamine‐assisted direct coprecipitation method. Fast‐firing (f.f.) processes, where sintering temperatures are reached in a short time to promote lattice diffusion, were compared with conventional sintering, for the formation of dense microstructures from the nanostructured powders. Highly dense SDC and GDC samples (96%) with reduced grain size (150 nm) were obtained by f.f. even at 1300°–1400°C and, unexpectedly, high electrical conductivity and low blocking effect at grain boundary was obtained. Conventionally sintered samples showed that the grain boundary resistivity decreased with increasing the grain size, in agreement with the increase in geometrical bulk volume/grain boundary area ratio. Conversely, f.f. samples showed grain boundary resistivity smaller for small grain size. The above effect was observed only for high dopant (>10% molar) contents. The combined effect of powder grain size, dopant content, and sintering temperature–time profile, can be exploited to tune ceria microstructures for specific ionic device applications.