Über heterotype Mischphasen bei Seltenerdoxyden. I

Bräuer, G.; Gradinger, H.

doi:10.1002/zaac.19542760502

Cited by 187 publications

(85 citation statements)

References 23 publications

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“…Figure 3 shows the lattice constant as a function of Nd contents. The lattice constant was proportional to the content of Nd-dopant, and this tendency was agreed with the previous work [12]. Figure 4 shows the occupancy, g of oxygen site as a function of Nd-dopant, x.…”

Section: Methodssupporting

confidence: 90%

Crystal Structure and Electron Density Distribution Analyses of NdxCe1−xO2−δ for Electrolyte by Rietveld/Maximum Entropy Method

Taguchi

Igawa

Birumachi

et al. 2015

e-J. Surf. Sci. Nanotech.

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We carried out the X-ray diffraction studies on the crystal structure and electron density distribution of Nd-doped CeO2 which is considered the candidate material as an electrolyte for solid oxide fuel cell by the combination of Rietveld refinement and maximum entropy method. We determined those crystal structural parameters with the space group, F m3m, which is the same as pure CeO2. The Ce and Nd ions randomly occupied the 4a site and O ion preferentially occupied the 8c site in NdxCe1−xO 2−δ . We observed the distribution of the electron conduction pathway through the 4a-8c and 8c-8c sites.

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Section: Methodssupporting

confidence: 90%

Crystal Structure and Electron Density Distribution Analyses of NdxCe1−xO2−δ for Electrolyte by Rietveld/Maximum Entropy Method

Taguchi

Igawa

Birumachi

et al. 2015

e-J. Surf. Sci. Nanotech.

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“…• La 0.6 Sr 0.4 Fe y Co 1-y O 3-x peaks by those of GDC 28,29 and the fact that the strong XRD signal from the GDC overwhelmed the signal from the La 0.6 Sr 0.4 Fe y Co 1-y O 3-x . As shown in Figure 6, phase pure La 0.6 Sr 0.4 Fe y Co 1-y O 3-x was obtained for all compositions after firing at 700…”

Section: Resultsmentioning

confidence: 99%

The Effect of Precursor Solution Desiccation or Nano-Ceria Pre-Infiltration on Various La_0.6Sr_0.4Fe_yCo_1-yO_3-xInfiltrate Compositions

Burye

Tang

Nicholas

2016

J. Electrochem. Soc.

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Here, electrochemical impedance spectroscopy, X-ray diffraction, and scanning electron microscopy were used to determine the effect of precursor solution desiccation and nano-ceria pre-infiltration on Solid Oxide Fuel Cell cathodes with various infiltrate compositions. The calcium chloride desiccation of citric acid containing La0.6Sr0.4FeO3-x (LSF), La0.6Sr0.4Fe0.8Co0.2O3-x (LSFC), La0.6Sr0.4Fe0.5Co0.5O3-x (LSCF55), La0.6Sr0.4Fe0.2Co0.8O3-x (LSCF), and La0.6Sr0.4CoO3-x (LSC) infiltrate precursor solutions reduced average infiltrate particle sizes from the ∼53 nm obtained with standard processing to ∼42 nm. Similarly, infiltration of the aforementioned La0.6Sr0.4FeyCo1-yO3-x precursor solutions into porous cathodes containing pre-infiltrated gadolinium doped ceria (GDC) particles reduced average La0.6Sr0.4FeyCo1-yO3-x infiltrate particle sizes from the ∼53 nm obtained with standard processing (i.e. in the absence of nano-GDC pre-infiltration) to ∼27 nm with nano-GDC pre-infiltration. These desiccation and nano-GDC pre-infiltration induced infiltrate particle size reductions resulted in improved cathode performance. For example, in comparison with the 650°C operating temperatures required for standard LSC-GDC cathodes to achieve a polarization resistance of 0.1 Ωcm2, identical cathodes subjected to desiccation or nano-GDC pre-infiltration achieved 0.1 Ωcm2 at 630°C and 570°C, respectively. These promising results suggest that precursor solution desiccation or nano-GDC pre-infiltration may be useful for reducing the sizes of a variety of SOFC infiltrate materials.

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“…Therefore, we identified the layer as a solid solution. Since GDC (lattice parameter 5.418 Å) 16 and YSZ (lattice parameter 5.120 Å) 17 are in the same group of fluorite structure, lattice parameter expectedly changes with changing mixture ratio. 18 The Ce/Zr border line is located ∼300 nm inward from the surface.…”

Section: Resultsmentioning

confidence: 99%

Mechanism of SrZrO₃Formation at GDC/YSZ Interface of SOFC Cathode

Chou

Inoue

Kawabata

et al. 2018

J. Electrochem. Soc.

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SrZrO 3 formation at the interface of gadolinia-doped ceria (GDC) interlayer and yttria-stabilized zirconia (YSZ) electrolyte is analyzed using high-resolution electron microscopy. SrZrO 3 is dispersed in the inter-diffusion layer on the GDC side from the Ce/Zr border. Zr, which diffuses into the GDC grain, contributes to the formation of SrZrO 3 . The crystallographic relationship among the SrZrO 3 grains and its neighboring GDC grains reveals that SrZrO 3 is formed at the surface, at the grain boundary, and inside the grain, while maintaining a highly matched boundary with the adjacent GDC grain. The matching of the interface boundary is confirmed by the O-lattice theory, according to which the threshold Zr/Ce ratio is 13/34. If Zr/Ce ratio in the GDC grain is higher than the threshold, SrZrO 3 may significantly grow into the grain. The conduction path for the oxygen ion is retained because the GDC grain containing Zr is split into the SrZrO 3 grain and the less-Zr-containing GDC grain. If Zr/Ce ratio is lower than the threshold, SrZrO 3 may be formed but will be limited by the amount of Zr diffusing from the adjacent region. Thus, the morphology of SrZrO 3 is strongly affected by the state of GDC grains in the inter-diffusion layer. Solid oxide fuel cells (SOFCs) represent a promising technology for converting chemical energy of fuel to electricity with high efficiency, and should find many commercial applications. In the recent developments of SOFCs, lanthanum strontium cobaltite ferrite (La,Sr)(Co,Fe)O 3 (LSCF), with mixed ionic-electronic conductivity, is widely used as the cathode material because it offers high electrochemical performance at intermediate temperatures. Since the most common electrolyte material, i.e. yttria-stabilized zirconia (YSZ), tends to react with LSCF to form highly resistive SrZrO 3 , a thin interlayer consisting of doped ceria, such as gadolinia-doped ceria (GDC), is generally introduced between the LSCF cathode and the electrolyte to prevent solid-state reaction. 1-3 Some manufactures have fabricated an interlayer dense enough to suppress Sr diffusion toward the electrolyte side, which is accompanied by no SrZrO 3 formation. 4 In general, however, the interlayer formed on the YSZ electrolyte by printing and high-temperature sintering becomes porous. Therefore, the interlayer cannot completely eliminate SrZrO 3 formation, and the SrZrO 3 is often formed near the ceria/zirconia interface. [5][6][7][8][9][10][11][12][13][14] The amount and distribution of SrZrO 3 formation depends on the heat-treatment temperature of the interlayer. Wankmüller et al. reported the influence of the sintering temperature of GDC interlayer on the morphology of SrZrO 3 formation. 13 When the sintering temperature of GDC interlayer was 1200 • C, heat-treatment of LSCF cathode at 1080 • C produced a detrimental layer of SrZrO 3 entirely covering the YSZ electrolyte surface. When the sintering temperature of GDC interlayer was higher than 1300 • C, the amount of SrZrO 3 formed decreased and the distributio...

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Über heterotype Mischphasen bei Seltenerdoxyden. I

Cited by 187 publications

References 23 publications

Crystal Structure and Electron Density Distribution Analyses of Nd<i><sub>x</sub></i>Ce<sub>1−</sub><i><sub>x</sub></i>O<sub>2−<i>δ</i></sub> for Electrolyte by Rietveld/Maximum Entropy Method

Crystal Structure and Electron Density Distribution Analyses of Nd<i><sub>x</sub></i>Ce<sub>1−</sub><i><sub>x</sub></i>O<sub>2−<i>δ</i></sub> for Electrolyte by Rietveld/Maximum Entropy Method

The Effect of Precursor Solution Desiccation or Nano-Ceria Pre-Infiltration on Various La_0.6Sr_0.4Fe_yCo_1-yO_3-xInfiltrate Compositions

Mechanism of SrZrO₃Formation at GDC/YSZ Interface of SOFC Cathode

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Über heterotype Mischphasen bei Seltenerdoxyden. I

Cited by 187 publications

References 23 publications

Crystal Structure and Electron Density Distribution Analyses of Nd<i><sub>x</sub></i>Ce<sub>1−</sub><i><sub>x</sub></i>O<sub>2−<i>&delta;</i></sub> for Electrolyte by Rietveld/Maximum Entropy Method

Crystal Structure and Electron Density Distribution Analyses of Nd<i><sub>x</sub></i>Ce<sub>1−</sub><i><sub>x</sub></i>O<sub>2−<i>&delta;</i></sub> for Electrolyte by Rietveld/Maximum Entropy Method

The Effect of Precursor Solution Desiccation or Nano-Ceria Pre-Infiltration on Various La0.6Sr0.4FeyCo1-yO3-xInfiltrate Compositions

Mechanism of SrZrO3Formation at GDC/YSZ Interface of SOFC Cathode

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Crystal Structure and Electron Density Distribution Analyses of Nd<i><sub>x</sub></i>Ce<sub>1−</sub><i><sub>x</sub></i>O<sub>2−<i>δ</i></sub> for Electrolyte by Rietveld/Maximum Entropy Method

Crystal Structure and Electron Density Distribution Analyses of Nd<i><sub>x</sub></i>Ce<sub>1−</sub><i><sub>x</sub></i>O<sub>2−<i>δ</i></sub> for Electrolyte by Rietveld/Maximum Entropy Method

The Effect of Precursor Solution Desiccation or Nano-Ceria Pre-Infiltration on Various La_0.6Sr_0.4Fe_yCo_1-yO_3-xInfiltrate Compositions

Mechanism of SrZrO₃Formation at GDC/YSZ Interface of SOFC Cathode