Microstructures and electrolytic properties of yttrium-doped ceria electrolytes: Dopant concentration and grain size dependences

Ou, Ding Rong; Mori, Toshiyuki; Ye, Fei; Takahashi, Motoi; Zou, Jin; Drennan, John

doi:10.1016/j.actamat.2006.04.003

Cited by 115 publications

(127 citation statements)

References 26 publications

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“…Though the measured conductivity includes contributions of both the grain boundaries and the bulk, it is believed that the decrease in conductivity is mainly due to the change in bulk conductivity because the grain size, and thereby the density of grain boundary, is similar in different samples. Specifically, as suggested in previous studies, [8][9][10][11][12] this decrease can be explained by the enhanced interaction between the oxygen vacancies and the segregated dopant cations in some regions named microdomains or nanosized domains. In addition, the oxygen-vacancy ordering may also affect the ionic conductivity.…”

Section: Resultssupporting

confidence: 57%

“…%. 10,11 Furthermore, brighter diffuse scatterings and clearer extra reflections likely appear on the patterns of Sm-and Gd-doped ceria. Though the contrast in SAED patterns could be influenced by sample thickness and exposure time, one can find a good consistence between the development of diffuse scatterings and extra reflections and the increase in oxygen-vacancy ordering revealed by the EELS study.…”

Section: B Structural Analysis Of the Orderingmentioning

confidence: 99%

“…[2][3][4] However, in heavily doped ceria, nanosized domains can form and give negative impacts on the ionic conduction. [8][9][10][11] These domains have higher dopant concentrations than the matrix and could provide deep traps for the oxygen vacancies. 10,12 As a result of the domain formation, the advantage of the dopant having an optimum radius disappears with increasing the doping level.…”

Section: Introductionmentioning

confidence: 99%

“…Because of the small size, the immature structure, and the lattice coherence with the fluorite-structured matrix, 10,11 the direct analysis on these domains is difficult and their crystal structure remains unclear. Despite this, it has been suspected that the negative impacts of domains on ionic conduction are partly related to its ordered structure, which may involve the local ordering of oxygen vacancies.…”

Section: Introductionmentioning

confidence: 99%

“…Despite this, it has been suspected that the negative impacts of domains on ionic conduction are partly related to its ordered structure, which may involve the local ordering of oxygen vacancies. [11][12][13] In cubic stabilized zirconia, a more familiar system, the local ordering of oxygen vacancies was also speculated, which has ordered structures depending on the composition ͑e.g., the dopant type and doping concentration͒ and the heat treatment. [14][15][16] Based on the study of x-ray diffraction, Welberry et al suggested that the local ordering in yttria-stabilized zirconia has a pyrochlorelike structure, in which the 1 2 ͗111͘ pairs of oxygen vacancies across cubes of oxygen anions containing the cations are allowed.…”

Section: Introductionmentioning

confidence: 99%

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Oxygen-vacancy ordering in lanthanide-doped ceria: Dopant-type dependence and structure model

et al. 2008

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Studies of electron energy loss spectroscopy and selected area electron diffraction ͑SAED͒ were systematically performed on 15 and 25 at. % lanthanide ͑Ln͒-doped ceria samples ͑Ln= Sm, Gd, Dy, and Yb͒, through which the local ordering of oxygen vacancies that develops with increase in doping level was confirmed in the sequence of ͑Gd, Sm͒ Ͼ DyϾ Yb. Furthermore, a monotone correlation between the development of the ordering and the degradation of ionic conductivity with increasing the doping concentration from 15 to 25 at. % was observed. Based on the analysis of SAED patterns, a structural model for the ordering of oxygen vacancies has been constructed, in which the arrangement of oxygen vacancies is similar to that in C-type Ln 2 O 3 oxides and the 1 2 ͗110͘ pairs of the vacancies are preferred. Then, the factors that can influence the formation of the ordering are discussed.

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Section: Resultssupporting

confidence: 57%

Section: B Structural Analysis Of the Orderingmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Oxygen-vacancy ordering in lanthanide-doped ceria: Dopant-type dependence and structure model

et al. 2008

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Nickel–Copper/Gadolinium‐Doped Ceria (CGO) Composite Electrocatalyst as a Protective Layer for a Solid‐Oxide Fuel Cell Anode Fed with Ethanol

Faro

Reis²,

Saglietti³

et al. 2014

ChemElectroChem

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A nickel–copper alloy is prepared by using the oxalate method and subsequent in situ reduction. The bimetallic alloy is mixed with gadolinium‐doped ceria (CGO) to obtain a composite material with mixed electronic–ionic conductivity. The catalytic and electrocatalytic properties of the composite material for ethanol conversion are described. Different conditions to simulate bio‐ethanol feed operation are selected. Electrochemical tests are performed by utilizing the NiCu/CGO cermet as a barrier layer in a conventional anode‐supported solid‐oxide fuel cell (AS‐SOFC). A comparative study between the modified cell and a conventional AS‐SOFC without the protective layer is made. A maximum power density of 277 mW cm−2@0.63 V is recorded in the presence of a mixture of ethanol–water for a cell containing the protective anodic layer compared with 231 mW cm−2@0.64 V for a bare cell under the same conditions. This corresponds to a 20 % increase in performance.

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Design of Active Sites on Nickel in the Anode of Intermediate‐Temperature Solid Oxide Fuel Cells using Trace Amount of Platinum Oxides

et al. 2018

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In recent years, the lowering of the operation temperature of solid oxide fuel cells (SOFCs) has attracted much attention owing to the trade‐off between the best performance and the life span of SOFCs. For this challenge, new active sites on the Ni surfaces in a Nickel–Yttria‐Stabilized Zirconia (Ni‐YSZ) cermet anode of SOFCs have been created by deposition of trace amounts of platinum oxide (PtOx) followed by an activation step of the anode at 1073 K in a hydrogen flow. The internal resistance (IR) free value (185 mA cm−2 at 0.8 V) observed for the single cell with an anode sputtered with a trace amount of PtOx (Pt content in anode: from 9 to 91 ppm) at 973 K is conspicuously higher than that of a similar single cell with a nonsputtered cermet anode (85 mA cm−2) at 0.8 V and 1073 K. Transmission electron microscopy microanalysis shows that the defect structure is formed on a partially oxidized Ni surface by active Pt species. Also, surface atomistic simulation on NiO (111) predicts the formation of Frenkel defect clusters with Pt cations, which partially cover the Ni surface. The formation of Frenkel defect clusters on the partially oxidized Ni surface (i.e., creation of new active sites for formation of water molecules) promotes the anode reaction, resulting in improvements in the anode performance of SOFC single cells at 973 K. Design of the aforementioned new active sites on Ni through sputtering of trace amounts of PtOx provides a great opportunity for “radical innovation” in the design of intermediate‐temperature SOFCs.

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Microstructures and electrolytic properties of yttrium-doped ceria electrolytes: Dopant concentration and grain size dependences

Cited by 115 publications

References 26 publications

Oxygen-vacancy ordering in lanthanide-doped ceria: Dopant-type dependence and structure model

Oxygen-vacancy ordering in lanthanide-doped ceria: Dopant-type dependence and structure model

Nickel–Copper/Gadolinium‐Doped Ceria (CGO) Composite Electrocatalyst as a Protective Layer for a Solid‐Oxide Fuel Cell Anode Fed with Ethanol

Design of Active Sites on Nickel in the Anode of Intermediate‐Temperature Solid Oxide Fuel Cells using Trace Amount of Platinum Oxides

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