Design of Electroceramics for Solid Oxides Fuel Cell Applications: Playing with Ceria

Abstract

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.

Communication: Different behavior of Young's modulus and fracture strength of CeO2: Density functional theory calculations

“…40 The experimental value is 5.41 Å. 41 According to these results, our value of 5.47 Å is in agreement with the previous results. On the other hand, the (2) are estimated by the least squares method, and are summarized in Table I.…”

Electrode materials: a challenge for the exploitation of protonic solid oxide fuel cells

“…Reducing the SOFC operating temperature leads to two main problems: a decrease in electrolyte conductivity and [19].…”

Ab initioinvestigation of defect formation at ZrO2-CeO2interfaces

“…[1][2][3][4] Yttria-stabilized zirconia (YSZ) and doped cerium oxide are the most established electrolyte materials for SOFCs, since they show a significant thermally activated oxygen mobility when they crystallize in a fluorite structure. 5,6 Another way to reduce the operating temperature is the fabrication of electrolytes in film form to reduce their ohmic resistance. Recently, the fabrication and characterization of highly conductive ionic thin-film electrolytes has taken a new direction, due to the observed enhancement of ionic conductivity in ionic hetero-structures.…”