Diffusion in Mixed Conducting Oxides: A Review

Doshi, R.R.; Routbort, J.L.; Alcock, C. B.

doi:10.4028/www.scientific.net/ddf.127-128.39

Cited by 11 publications

(3 citation statements)

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“…The table below shows the equilibrium electrical conductivity of SSC at various temperatures and the two oxygen partial pressures employed in the conductivity relaxation experiments. The increase in conductivity with pO 2 confirms p-type conduction, as previously observed in this material [21]. competitive with (k) other SOFC candidate cathode materials in terms of chemical diffusivity and surface exchange coefficients, respectively.…”

Section: Resultssupporting

confidence: 82%

Oxygen transport and surface exchange properties of Sr0.5Sm0.5CoO3−δ

Yeh¹,

Routbort²,

Mason³

2013

Solid State Ionics

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Section: Resultssupporting

confidence: 82%

Oxygen transport and surface exchange properties of Sr0.5Sm0.5CoO3−δ

Yeh¹,

Routbort²,

Mason³

2013

Solid State Ionics

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“…To mitigate some of these problems, recent efforts have been aimed toward lowering the operating temperature of SOFCs to an intermediate temperature ͑IT͒ regime of 600-800°C, i.e., IT-SOFCs. [1][2][3][4] Although oxygen chemical diffusion in mixed conducting electrodes such as LSCF and LSM is relatively fast at elevated temperatures, [5][6][7][8][9] their catalytic activities and transport rates decrease precipitously with temperature that leads to increased activation losses at ITs. 1,[10][11][12][13] In recent years, the thrust of our research effort has been aimed to further lower the operating temperature of SOFCs to a regime between 300 and 500°C by employing thin-film structures of the YSZ electrolyte and electrodes.…”

mentioning

confidence: 99%

Nanopore Patterned Pt Array Electrodes for Triple Phase Boundary Study in Low Temperature SOFC

Kim

Hsu

Connor

et al. 2010

J. Electrochem. Soc.

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This paper describes the fabrication and investigation of morphologically stable model electrode structures with well-defined and sharp platinum/yttria-stabilized zirconia ͑YSZ͒ interfaces to study geometric effects at triple phase boundaries ͑TPBs͒. A nanosphere patterning technique using monodispersed silica nanoparticles, which are applied to the YSZ surface by the LangmuirBlodgett method, is employed to deposit nonporous platinum electrodes containing close-packed arrays of circular openings 300-400 nm in diameter through which the underlying YSZ surface is exposed to the gas phase. These nanostructured dense Pt array cathodes exhibited better structural integrity and thermal stability at the solid oxide fuel cell ͑SOFC͒ operating temperature of 450-500°C when compared to porous sputtered Pt electrodes. More importantly, electrochemical studies on geometrically well-defined Pt/YSZ sharp interfaces demonstrated that the cathode impedance and cell performance both scale almost linearly with the aerial density of TPB length. These controlled experiments also demonstrated that when normalized with respect to TPB length, the performance of different cells with different TBP densities agree well each other, indicating that TPB length governs cell performance especially in the activation polarization regime, as expected. Cells with a higher TPB density achieved better fuel cell performance in terms of higher power density and lower electrode impedance.Solid oxide fuel cells ͑SOFCs͒ are efficient energy conversion devices that are being developed for practical applications. Due to large activation energies ͑ϳ1 eV͒ for oxide ion transport in solid oxide electrolytes and relatively sluggish oxygen reduction reaction at the cathode, SOFCs are usually operated at elevated temperatures ͑800-1000°C͒ to obtain practically meaningful fluxes and fuel cell performance. Typically, an SOFC element is made of an yttriastabilized zirconia ͑YSZ͒ electrolyte layer, a mixed conducting ceramic cathode such as La 1−x Sr x Co 1−y Fe y O 3 ͑LSCF͒ and La 1−x Sr x MnO 3−␦ ͑LSM͒, and a cermet anode such as Ni/YSZ.The operation of SOFCs at elevated temperatures may be desirable for enhanced kinetics and transport purposes but poses serious challenges in microstructural and thermal stability, seal integrity, aging and degradation, thermal cycling, and cost of materials and fabrication. To mitigate some of these problems, recent efforts have been aimed toward lowering the operating temperature of SOFCs to an intermediate temperature ͑IT͒ regime of 600-800°C, i.e., IT-SOFCs. 1-4 Although oxygen chemical diffusion in mixed conducting electrodes such as LSCF and LSM is relatively fast at elevated temperatures, 5-9 their catalytic activities and transport rates decrease precipitously with temperature that leads to increased activation losses at ITs. 1,[10][11][12][13] In recent years, the thrust of our research effort has been aimed to further lower the operating temperature of SOFCs to a regime between 300 and 500°C by employing thin-film structu...

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“…Some of the oxide ion electrolytes are electronic insulators while others are mixed oxide ion and electronic conductors [4].Oxide materials that exhibit high ionic conductivity have attracted considerable attention for many years owing to both the range of applications (as fuel cell etc. and catalysts) and a fundamental fascination with ionic transport in crystalline solids [5][6][7][8][9][10][11][12][13]. Zirconia based ceramics are widely studied because of their excellent electrical and mechanical properties [14].…”

Section: Introductionmentioning

confidence: 99%

Electrical Conductivity and Phase Transition Studies in the ZrO<sub>2</sub>-CdO System

Beg

Haneefaa

2012

DDF

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The Solid Solution of ZrO2: Cdo Was Prepared by the Conventional Solid-State Reaction. Effect of Dopant Concentration on the Electrical Conductivity of ZrO2Was Studied for Different Compositions at Different Temperatures. the Conductivity Increases with the Addition of Cdo due to the Migration of Vacancies. the Conductivity Increases with Rise in Temperature up to 180°C and Thereby Decreases due to the Collapse of Fluorite Framework. A Second Rise in Conductivity at High Temperature beyond 460°C Is due to the Phase Transition of ZrO2from Monoclinic to Tetragonal. DSC, X Ray Powder Diffraction, Impedance Measurements and FTIR Spectral Studies Were Carried Out for Confirming the Doping Effect and Transitions in ZrO2. the Addition of Cdo to Zro2 Shifted the Phase Transition of ZrO2to Higher Temperatures as Confirmed by the DSC Results. the Occurrence of Single Semi Circle with a Low Frequency Inclined Spike Indicates that the Conductivity Is Mainly due to the Movement of Oxide Ions.

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Diffusion in Mixed Conducting Oxides: A Review

Cited by 11 publications

References 0 publications

Oxygen transport and surface exchange properties of Sr0.5Sm0.5CoO3−δ

Oxygen transport and surface exchange properties of Sr0.5Sm0.5CoO3−δ

Nanopore Patterned Pt Array Electrodes for Triple Phase Boundary Study in Low Temperature SOFC

Electrical Conductivity and Phase Transition Studies in the ZrO<sub>2</sub>-CdO System

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