Total electrical conductivity and defect structure of ZrO2–CeO2–Y2O3–Gd2O3 solid solutions

Tsoga, A.; Naoumidis, A.; Stöver, D.

doi:10.1016/s0167-2738(00)00477-x

Cited by 143 publications

(93 citation statements)

References 5 publications

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“…GDC sintering temperature should be carefully chosen, considering the decrease in ionic conductivity upon growth of the solid solution phase. 18 Even for pulsed laser deposition (PLD) for the fabrication of GDC interlayer, post annealing is necessary to reduce the cation diffusion path through the grain boundary perpendicular to the surface. After post annealing at ∼1300 • C, Zr diffused outward and SrZrO 3 was formed at 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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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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“…However, at these temperatures CGO and YSZ form a solid solution which has a significantly lower oxide ion conductivity compared to both of the pure compounds. [21][22][23] An alternative way to fabricate CGO barriers are by physical vapor deposition techniques such as magnetron sputtering, pulsed laser ablation, and electron beam evaporation. [16,20,24] Studies comparing deposition techniques have provided evidence that CGO barrier layers fabricated by reactive magnetron sputtering show better performance.…”

Section: Introductionmentioning

confidence: 99%

Strontium Diffusion in Magnetron Sputtered Gadolinia‐Doped Ceria Thin Film Barrier Coatings for Solid Oxide Fuel Cells

Sønderby

Popa

et al. 2013

Advanced Energy Materials

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is prepared to simulate a solid oxide fuel cell. This setup allows observation of Sr diffusion by observing SrZrO 3 formation using X-ray diffraction while annealing. Subsequent electron microscopy confirms the results. This approach presents a simple method for assessing the quality of CGO barriers without the need for a complete fuel cell test setup. CGO films with thicknesses ranging from 250 nm to 1.2 µm are tested at temperatures from 850 °C to 950 °C which yields an in-depth understanding of Sr diffusion through CGO thin films that may be of high scientific and technical interest for implementation of novel fuel cell materials. Sr is found to diffuse along column/grain boundaries in the CGO films but by modifying the film thickness and microstructure the breaking temperature of the barrier can be increased.2 2

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“…34) The solid solution has significantly lower conductivity compared with YSZ and GDC. 35) Furthermore, the MSCs cannot be sintered at high temperatures, because the heat-resistivity of porous metallic substrates is lower than those of ceramic and cermet substrates. Electrophoretic deposition (EPD), 23) electrochemical vapor deposition (EVD), 36) and atmospheric plasma spray (APS) 37) were employed to form dense electrolytes to prevent sintering at high temperatures.…”

Section: )mentioning

confidence: 99%

Metal-supported microtubular solid oxide fuel cells with ceria-based electrolytes

Sumi

Shimada

Yamaguchi

et al. 2017

J. Ceram. Soc. Japan

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Metal-supported solid oxide fuel cells (SOFCs) are expected to lower operating temperature and improve reliability. The residual crushing strength and electrical conductivity of porous metallic nickel microtubes were higher than those of nickel-gadoliniadoped ceria (Ni-GDC) cermets. The maximum power density of the metal-supported microtubular SOFC with GDC electrolyte was approximately three times higher than that of a conventional anode-supported microtubular SOFC with yttria-stabilized zirconia electrolyte at a relatively low temperature of 550°C. The metal-supported microtubular SOFCs have a potential to be applied not only in stationary devices, such as residential combined heat/power systems, but also in portable power sources and vehicles.

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Total electrical conductivity and defect structure of ZrO2–CeO2–Y2O3–Gd2O3 solid solutions

Cited by 143 publications

References 5 publications

Mechanism of SrZrO₃Formation at GDC/YSZ Interface of SOFC Cathode

Mechanism of SrZrO₃Formation at GDC/YSZ Interface of SOFC Cathode

Strontium Diffusion in Magnetron Sputtered Gadolinia‐Doped Ceria Thin Film Barrier Coatings for Solid Oxide Fuel Cells

Metal-supported microtubular solid oxide fuel cells with ceria-based electrolytes

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Total electrical conductivity and defect structure of ZrO2–CeO2–Y2O3–Gd2O3 solid solutions

Cited by 143 publications

References 5 publications

Mechanism of SrZrO3Formation at GDC/YSZ Interface of SOFC Cathode

Mechanism of SrZrO3Formation at GDC/YSZ Interface of SOFC Cathode

Strontium Diffusion in Magnetron Sputtered Gadolinia‐Doped Ceria Thin Film Barrier Coatings for Solid Oxide Fuel Cells

Metal-supported microtubular solid oxide fuel cells with ceria-based electrolytes

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Mechanism of SrZrO₃Formation at GDC/YSZ Interface of SOFC Cathode

Mechanism of SrZrO₃Formation at GDC/YSZ Interface of SOFC Cathode