Anomalous conductivity and microstructure in gadolinium doped ceria prepared from nano-sized powder

Sakai, Natsuko; Xiong, Ying; Yamaji, Katsuhiko; Yokokawa, Harumi; Terashi, Yoshitake; Seno, Hiroaki

doi:10.1016/j.ssi.2006.03.049

Cited by 18 publications

(31 citation statements)

References 16 publications

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“…We have confirmed in TEM/EDS study that the yttrium or gadolinium concentration is anomalously higher at the grain boundary than in the bulk in both Y 0.2 Ce 0.8 O 1.9 (YDC) or Gd 0.2 Ce 0.8 O 1.9 (GDC) polycrystalline bodies [13]. The anomalously high segregation of gadolinium and high hole conductivity were observed for GDC crystalline bodies which was prepared from nanosized powder [13]. Those facts indicate that the gadolinium segregation from bulk to grain boundary is a common phenomenon in rare earth doped ceria.…”

Section: Resultssupporting

confidence: 61%

Anomalous transport property at surface and interface of metal/rare earth doped ceria

et al. 2008

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Section: Resultssupporting

confidence: 61%

Anomalous transport property at surface and interface of metal/rare earth doped ceria

et al. 2008

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“…Sakai et al [92] reported that GDC shows anomalous hole conductivity in the oxidative atmosphere when GDC pellet was fabricated from nanopowders. If these phenomena happen in GDC, it is expected that the electrode reaction mechanism will change in addition to decrease in electromotive force due to the high hole conductivity comparable to the ionic conductivity.…”

Section: Original Research Papermentioning

confidence: 99%

Recent Achievements of NEDO Durability Project with an Emphasis on Correlation Between Cathode Overpotential and Ohmic Loss

et al. 2017

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Long-term performance testes by CRIEPI (Central Research Institute for Electric Power Industry) on six industrial stacks have revealed an interesting correlation between cathode polarization loss and ohmic loss. To make clear the physicochemical meaning of this correlation, detailed analyses were made on the conductivity degradation of YSZ electrolyte in button cells and then on the ohmic losses in the industrial cells in terms of time constants which are determined from speed of the tetragonal transformation through the Y diffusion from the cubic phase to the tetragonal phase. In some cases, shorter time constants (faster degradations) were detected than those expected from the two-time-constant (with and without NiO reduction effects) model, suggesting that additional ohmic losses after subtracting the contribution from the tetragonal transformation must be caused from other sources such as cathode-degradation inducing effects. Main cathode degradations can be ascribed to sulfur poisoning due to contamination in air in the CRIEPI test site. An important feature was extracted as this cathode degradations became more severe when the gadolinium-doped ceria (GDC) interlayers were fabricated into dense film. Plausible mechanisms for cathode degradations were proposed based on the Sr/Co depletion on surface of lanthanum strontium cobalt ferrite (LSFC) in the active area. Peculiar cathode degradations found in stacks are interpreted in term of changes in surface concentration by reactions with sulfur oxide, electrochemical side reactions for water vapor emission or Sr volatilization, and diffusion of Sr/Co from inside LSCF.

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“…The preparation of nanosized ceria powders as starting material for dense electrolyte applications has been investigated intensively 23,30–36 . The selection of the proper synthesis method is very important in determining the size and in obtaining homogenous composition of the powders.…”

Section: Introductionmentioning

confidence: 99%

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

Esposito

Traversa

2008

Journal of the American Ceramic Society

240

196

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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.

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Anomalous conductivity and microstructure in gadolinium doped ceria prepared from nano-sized powder

Cited by 18 publications

References 16 publications

Anomalous transport property at surface and interface of metal/rare earth doped ceria

Anomalous transport property at surface and interface of metal/rare earth doped ceria

Recent Achievements of NEDO Durability Project with an Emphasis on Correlation Between Cathode Overpotential and Ohmic Loss

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

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