Microstructure evolution and cation interdiffusion in thin Gd2O3 films on CeO2 substrates

Rockenhäuser, Christian; Butz, Benjamin; Schichtel, N.; Janek, Jürgen; Oberacker, R.; Hoffmann, Michael J.; Gerthsen, D.

doi:10.1016/j.jeurceramsoc.2013.11.043

Cited by 14 publications

(8 citation statements)

References 36 publications

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“…The bixbyite structure is occasionally observed. Investigations of the Gd 2 O 3 –CeO 2 system − indicate a continuous transition from the cubic fluorite to the bixbyite structure with increasing Gd content via formation of small-scale precipitates and domains of the bixbyite structure. Literature data on the compositional stability range of the bixbyite structure vary, but nanoscale domains were observed at Gd concentrations higher than 10 atom % .…”

Section: Discussionmentioning

confidence: 99%

Gd_0.2Ce_0.8O₂ Diffusion Barrier Layer between (La_0.58Sr_0.4)(Co_0.2Fe_0.8)O_3−δ Cathode and Y_0.16Zr_0.84O₂ Electrolyte for Solid Oxide Fuel Cells: Effect of Barrier Layer Sintering Temperature on Microstructure

Wilde

Störmer

Szász

et al. 2018

ACS Appl. Energy Mater.

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Combining high-performance (La 0.58 Sr 0.4 )(Co 0.2 Fe 0.8 )O 3-δ (LSCF) cathodes with Y-doped ZrO 2 (YDZ) electrolytes in solid oxide fuel cells leads to the formation of SrZrO 3 (SZO) as secondary phase with exceedingly low oxygen ion conductivity and poor catalytic capability. A promising prevention strategy is the insertion of Gd-doped CeO 2 (GDC) as a reaction barrier. In this work, screen-printed GDC layers were sintered on YDZ substrates at temperatures varying from 1100 to 1400 °C. Subsequently, screen-printed LSCF was sintered on top at 1080 °C. The goal of this work was to understand microstructure formation during the two subsequent sintering processes by the analysis of nanometer-scale elemental distributions, crystal structures, and grain sizes of this extended cathode/ electrolyte interface as a function of the GDC sintering temperature. Various representative regions on all samples were analyzed by transmission electron microscopy combined with energy dispersive X-ray spectroscopy with high spatial resolution. For the lowest GDC sintering temperature an almost continuous ion-blocking SZO layer is formed during subsequent LSCF sintering. Although GDC densification does not occur, SZO formation is increasingly suppressed if higher GDC sintering temperatures are applied. This is attributed to a dense interdiffusion layer forming at the GDC/YDZ interface, which increases in thickness with GDC sintering temperature and contains a Zr-depleted region adjacent to the porous GDC layer. The dense and Zr-poor sublayer prevents the reaction of Sr species transported via gas phase during LSCF sintering with the Zr-rich YDZ substrate. The microstructural features have a pronounced influence on the electrical performance. Electrochemical impedance spectroscopy measurements at open circuit voltage conditions reveal differences in the polarization resistance of up to 3 orders of magnitude.

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Section: Discussionmentioning

confidence: 99%

Gd_0.2Ce_0.8O₂ Diffusion Barrier Layer between (La_0.58Sr_0.4)(Co_0.2Fe_0.8)O_3−δ Cathode and Y_0.16Zr_0.84O₂ Electrolyte for Solid Oxide Fuel Cells: Effect of Barrier Layer Sintering Temperature on Microstructure

Wilde

Störmer

Szász

et al. 2018

ACS Appl. Energy Mater.

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“…37 Neither the formation of the I2 1 3 structure nor broad Gd concentration plateaus in interdiffusion profiles were observed in this material system. 37 Neither the formation of the I2 1 3 structure nor broad Gd concentration plateaus in interdiffusion profiles were observed in this material system.…”

Section: (1) Microstructure Evolution and Phase Formationmentioning

confidence: 72%

“…[37]. High-purity CeO 2 powder was purchased from Treibacher Industrie AG (Althofen, Austria) with impurity concentrations below 20 ppm for Fe, Al, Zn, and Sn and 20 ppm for Si.…”

Section: Methodsmentioning

confidence: 99%

Microstructure Evolution and Cation Interdiffusion in Thin Sm₂O₃ Films on CeO₂ Substrates

et al. 2014

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Samaria (Sm 2 O 3 ) thin films with a thickness of 180 nm were deposited on polycrystalline CeO 2 substrates by pulsed layer deposition to study phase formation and bulk cation interdiffusion in the Ce 1x Sm x O 2x/2 system after annealing at temperatures between 987°C and 1266°C. Transmission electron microscopy combined with electron diffraction and analytical techniques was applied for phase determination. The cubic fluorite and cubic bixbyite phases were observed at low and intermediate Sm concentrations. The monoclinic phase occurs only at very high Sm concentrations due to the low Ce-solubility in Sm 2 O 3 . Furthermore, a cubic phase with I2 1 3 structure was observed at higher Sm concentrations. Cation interdiffusion coefficients were derived from Sm concentration profiles across the Sm 2 O 3 /CeO 2 interface using the diffusion-couple solution of the diffusion equation. The temperature dependence of interdiffusion coefficients is well described by an Arrhenius-type relation, which yields an activation enthalpy of 2.26 eV/atom for bulk cation interdiffusion.H. Chan-contributing editor Manuscript No. 34455.

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“…The diffusion length, defined as 2 ffiffiffiffiffi Dt p , provides a good measure of how far a concentration change can propagate in a given time, t, and diffusivity, D. The bulk diffusivity of Gd into CeO 2 has previously been measured in the form of a diffusion couple, using energy-dispersive x-ray spectroscopy in a transmission electron microscope, avoiding the grainboundary contributions to give an activation energy of 2.29 eV. 43 Using these values for D, the calculated diffusion length is <0.07 nm for 2 hours at 800°C, and therefore is too low to describe the segregation observed in this work. Much higher cation diffusivities have been measured for Gd 0.22 Ce 0.78 O 1.89 nanocrystalline films from grain coarsening experiments, yielding an activation energy of 1.32 eV, which was attributed to grain-boundary diffusion.…”

Section: Discussionmentioning

confidence: 99%

Can solute segregation in ceramic materials be reduced by lattice strain?

2017

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Lattice strain is a relatively unexplored route to modify the degradation effects in functional oxides for high-temperature electrochemical devices. In this paper, we present results on the segregation of Gd to the surface of strained Gd0.1Ce0.9O2-δ films using low-energy ion scattering to assess the surface composition. The potential for strain-modified segregation is discussed as well as the challenges in studying and implementing it

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Microstructure evolution and cation interdiffusion in thin Gd2O3 films on CeO2 substrates

Cited by 14 publications

References 36 publications

Gd_0.2Ce_0.8O₂ Diffusion Barrier Layer between (La_0.58Sr_0.4)(Co_0.2Fe_0.8)O_3−δ Cathode and Y_0.16Zr_0.84O₂ Electrolyte for Solid Oxide Fuel Cells: Effect of Barrier Layer Sintering Temperature on Microstructure

Gd_0.2Ce_0.8O₂ Diffusion Barrier Layer between (La_0.58Sr_0.4)(Co_0.2Fe_0.8)O_3−δ Cathode and Y_0.16Zr_0.84O₂ Electrolyte for Solid Oxide Fuel Cells: Effect of Barrier Layer Sintering Temperature on Microstructure

Microstructure Evolution and Cation Interdiffusion in Thin Sm₂O₃ Films on CeO₂ Substrates

Can solute segregation in ceramic materials be reduced by lattice strain?

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Microstructure evolution and cation interdiffusion in thin Gd2O3 films on CeO2 substrates

Cited by 14 publications

References 36 publications

Gd0.2Ce0.8O2 Diffusion Barrier Layer between (La0.58Sr0.4)(Co0.2Fe0.8)O3−δ Cathode and Y0.16Zr0.84O2 Electrolyte for Solid Oxide Fuel Cells: Effect of Barrier Layer Sintering Temperature on Microstructure

Gd0.2Ce0.8O2 Diffusion Barrier Layer between (La0.58Sr0.4)(Co0.2Fe0.8)O3−δ Cathode and Y0.16Zr0.84O2 Electrolyte for Solid Oxide Fuel Cells: Effect of Barrier Layer Sintering Temperature on Microstructure

Microstructure Evolution and Cation Interdiffusion in Thin Sm2O3 Films on CeO2 Substrates

Can solute segregation in ceramic materials be reduced by lattice strain?

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Gd_0.2Ce_0.8O₂ Diffusion Barrier Layer between (La_0.58Sr_0.4)(Co_0.2Fe_0.8)O_3−δ Cathode and Y_0.16Zr_0.84O₂ Electrolyte for Solid Oxide Fuel Cells: Effect of Barrier Layer Sintering Temperature on Microstructure

Gd_0.2Ce_0.8O₂ Diffusion Barrier Layer between (La_0.58Sr_0.4)(Co_0.2Fe_0.8)O_3−δ Cathode and Y_0.16Zr_0.84O₂ Electrolyte for Solid Oxide Fuel Cells: Effect of Barrier Layer Sintering Temperature on Microstructure

Microstructure Evolution and Cation Interdiffusion in Thin Sm₂O₃ Films on CeO₂ Substrates